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JOURNAL 


o  p 


NATURAL   PHILOSOPHY,   CHEMISTRY, 
AND  THE  ARTS  : 


ILLLUSTRATED    WITH  ENGRAVINGS. 


BY  WILLIAM  NICHOLSON. 

^^==^^=^=^=—- — ■ ' ■         -— ■ 


VOL.    II. 


LONDON: 

HUNTED  FOR  THE  AUTHOR,  AND  SOLD  BY  G.  G.  AND  J,  ROBINSON,  PATERNOSTER-ROW. 


M.DCC.XCIX. 


»^//. 


.<0T 


TABLE    OF    CONTENTS 


TO   THIS    SECOND    VOLUME. 


APRIL    1798. 


[.A 


I.  Jlx.  memoir  and  new  Experiments  on  the  artificial  Cinnabar  of  Mr. 
Kirchoff.  By  the  Count  ApoUos  de  Moullln  Poufchkin,  Chamberlain  to 
his  Majefty,  the  Emperor  of  all  the  Ruffias,  Vice-Prefident  of  the  College 
of  Mines,  Honorary  Member  of  the  Imperial  Academy  of  Sciences  at 
Peterfburgh,  &cc.  &;c.         —         —         —  —  —         page  i. 

Inconveniences  of  the  prefent  method  of  manufafturing  cinnabar.  Annotation  defcribing  that 
method.  New  procefs  in  the  humid  way,  by  trituration  of  tlie  black  fulphuret  of  mercufy  in  an 
heated  folution  of  pqtaih.  Chief  difficulty  of  this  procefs.  Experiments  to  afcertain  the  nature 
of  the  procefs,  and  to  render  it  certain  in  the  large  way.  Beautiful  cinnabar  refembling  carmine. 
Inftruftions  to  manufadurers. 

II.  On  the  luminous  appearance  faid  to  be  exhibited  by  Phofphorus  in  azotic 
Gas.  By  Dr.  Alexander  Nicholas  Scherer,  Counfellor  of  the  Mines  to  his 
Serene  Highnefs  the  Duke  of  Saxon  Weimar  —  —         p.  8 

Hiftory  of  Goettling's  obfervations  and  theory  of  phofphorus  fhining  in  azote.  Inveftigations  of 
the  fame  fubjeft  by  various  German  chemifts  and  others. 

III.  On  Mr.  Lazowfki's  new  Barometer,  or  Weather-Inftrument.  By  a 
Correfpondent        —  ■ —  —         —  '■ —  —         p.  11 

Account  of  founds  emitted  by  a  wire  on  change  of  weather.  Attempts  to  verify  the  faft.  Inquiry 
whether  the  wire  aSed  like  Ofwald's  ./Eolian  harp. 

IV.  Obfervations  on  Scylla  and  Charybdis.  By  the  Abbe  Lazzaro  Spal- 
lanzani,  Profeffor  of  Natural  Hiftory,  at  Pavi,  F.  R.  S.  &c.        —       p.  12 

Vol.  11.— March   iyg()^  b  Ancient 


• 


It 


CONTENTS. 


Ancient  defcription  of  Scylla  and  Charybdis  compared  with  their  prefent  flate.  Caufes  why  Scylla 
is  dangerous  to  mariners.  Inftance.  Situation  of  Charybdis,  ufually  fuppofed  to  be  a  whirlpool. 
An  excurfion  to  the  fpot.  Miftake  of  Homer  with  regard  to  the  fituation  and  nature  of  this  phe- 
nomenon. Modern  improvements  in  fhip-biiilding  and  navigation  have  rendered  Scylla  and 
Charybdis  lefs  dangerous. 

V.  Inftru£lions  for  refining  Saltpetre  by  a  new  Procefs.     By  J.  A.  Chaptal, 
J.  P.  Champy,  and  Bonjour  —  —  —  —     P-  23 

reticular  direftions  for  refining  crude  faltpetre — by  percolation — folution  in  boiling  water — cryf- 
'     tallization  by  cooling  with  agitation — waftiing,  draining,  and  drying.    Great  expedition,  cheap- 
nefs,  and  excellence  of  this  method.     Examination  of  other  proceilies. 

VI.  On  the  Light  emitted  by  fuperfaturated  Borate  of  Soda,  or  common 
BoraXj     By  Mr.  F.  Accum  —  —  —  p.  28.  ' 

Borax,  when  ftruck,  emits  an  uncommonly  white  flafli. 

VII.  New  Conftruftion  of  the  Air-pump.  By  Sir  George  S.  Mackenzie, 
Bart.  —  —  —  —  —  il>. 

Air-pump  with  a  folid  pifton,  both  valves  in  the  bottom  of  the  barrel,  and  the  valve  from  the  re- 
ceiver opened  mechanically.  Limits  of  effeA  in  this  pump,  and  alfo  in  thofe  of  Cuthbertfon, 
Prince,  W.  N.  and  Sadler. 

VIII.  On  the  A£tion  of  Nitre  upon  Gold  and  Platina.  By  Smithfon  Tennant, 
Efq.  F.R.S.  —  —  ■—  —  p.  JO 

Gold  is  diflblved  in  nitre  by  ftrong  heat,  and  rendered  partly  foluble  in  water.  When  this  metal 
is  diflblved  in  alkali,  it  is  thrown  down  in  the  metallic  flate  by  nitre  or  nitrous  acid,  provided 
thefe  be  partly  deprived  of  oxygen.  Platina  is  alfo  foluble  in  ignited  nitre,  and  rendered  partly 
foluble  in  water.     Silver  is  fcarcely  afted  upon  by  nitre. 

IX.  An  Account  of  the  Caufes  of  Alteration  injurious  to  the  Quality  of  Corn, 
and  the  Means  of  preventing  this  Change.  By  B.  G.  Sage,  of  the  ci-devant 
Academy  of  Sciences,  Profeffor  of  Chemiftry  and  Mineralogy  in  the  School 
des  Mines  de  la  Monnoie        — -  —  —  —        P-^3^ 

When  corn  is  houfed  without  fufficient  drying,  it  heats,  ferments,  and  the  elaftic  gluten  is  no  longer 
found;  at  the  fame  time  that  it  lofes  its  vegetative  and  nutritive  powers. 

X.  Defcription  of  an  Apparatus  for  difengaging  Oxygen  Gas,  and  applying 
it  to  the  bed  Advantage.  Conftrufted  by  James  Sadler,  Efq.  Chemift  to 
the  Admiralty.  To  wbich  are  added,  Obfervations  upon  the  Blow-pipe. 
ByW.  N.        —  —  —  —  —        p.  33 

Simple  furnace  for  extricating  oxygen,  and  for  other  general  experiments.  Apparatus  for  heating 
the  ftream  of  oxygen  when  ufed.  Experiments  on  the  denfity  and  velocity  of  air  from  the  com- 
mon blow-pipe.  Dedudion  of  the  fize  of  bellows  required  to  produce  the  fame  effeift.  Obfer- 
vations on  the  air-veffel  of  fire-engines,  tending  to  fhow  in  what  circumftances  it  may  be  ap- 
plied to  blowing  engines. 

XI,  A 


CONTENTS. 


ill 


XI.  A  fliort  Account  of  the  Life  of  Pelletier.  Read  at  the  public  Sitting  of 
the  National  Inftitute  of  France,  the  15th  Venderaiare,  in  the  year  VI.  by- 
Citizen  Laffus,  Secretary  to  the  Clafs  of  Natural  Philofophy  and  Mathe- 
matics —  —  —  —  —  P-  37 

XII.  Extrafts  from  the  Syfteme  du  Monde  of  M.  La  Place        —        p.  39 

Irregular  figure  of  the  terreftrial  meridian.  Effefts  of  planetary  rotation.  How  the  rotation  may- 
have  been  caufed  by  the  original  projeftile  impulfe.  On  pendulums.  Laws  of  therotation  of  a 
planet,  and  its  atmofphere.  Formation  of  planets  from  the  folar  atmofphere.  Probability 
and  effefts  of  a  comet  flrikirig  the  earth.  Indications  that  fuch  an  event  has  formerly  liap- 
pened, 

XIII.  On  the  Preparation  of  the  concrete  Acid  of  Lemons.  By  Dize,  Apo- 
thecary-in-chief to  the  French  Army,  charged  with  the  Infpeftion  of  the 
general  Magazine  of  Medicines  —  —  —  p.  4.3 

Scheele's  procefs  repeated  in  the  large  way.     Theoretical  remarks — affinities  of  the  purified  acid. 

XIV.  Ufeful  Notices  refpefting  various  Objefts. — Governor  for  regulating 
the  Motions  of  Steam  Engines — Amelioration  of  Oil        —        —     ?♦  46 

Mr.  Bunce  of  the  admiralty  invented  the  governor  for  fleam  engines — Different  methods  of  purify- 
ing oil. 

New  Publications  —         —  —  —  ?•  47 

Sraeaton's  Reports,  with  an  account  of  the  Society  of  Civil  Engineers. 


MAY    1798. 

I.  On  the  maintaining  Power  of  Clocks  and  Watches         —  —    P- 49 

Eflential  requifites  in  the  maintaining  power  of  a  good  time-piece.  Caufes  of  irregularity  and  their 
remedies.  Efcapements.  Defcription  of  the  crown-wheel  efcapement.  Its  great  antiquity; 
advantages  and  defers.  Anchor-pallets  and  fwing-wheel.  Graham's  dead-beat,  in  what  re- 
fpeds  beneficial.  Horizontal  efcapement;  invented  in  1704.  Free  efcapement,  with  a  pallet 
and  detent  for  watches  ;  invented  in  1704.  Free  efcapement,  with  a  pallet  and  detent  for  watches; 
invented  in  1 748  by  Le  Roy.  Its  good  qualities.  Variation  adapted  to  a  clock.  Mudge's  de- 
tached efcapement.  Comparifon  of  this  with  the  pallet  and  detent.  Detached  efcapement 
of  Gumming  organized  and  publifhed  before  that  of  Mudge.  Adaptation  of  Mudge's  invention 
to  a  clock.  A  new  efcapement  for  a  clock ;  requiring  no  oil,  having  no  detent,  nor  aftion  during 
the  time  of  repofe. 

II.  Copy  of  a  Letter  from  ProfeflTor  Wilfon,  of  Glafgow,  on  the  Art  of  mul- 
tiplying Copies  of  engraved  Plates  and  Stamps  in  relief.  —         p.  60 

The  greateft  difficulty  of  printing  from  glafs  plates  arifes  from  their  fragility.  It  may  be  obviated  by 
cementing  them  to  metal.  Taffi's  impreffions  in  glafs  from  engraved  plates.  Great  utility  of 
fuch  copies  for  printing.    Copies  of  wood  cuts  by  the  fame  method. 

b  a  in.  In- 


i^  CONTENTS. 

III.  Inftruftions  concerning  the  Manufacture  of  Steel  and  its  Ufes.  By  Van- 
dermonde,  Monge,  and  Berthollet.  Publiflied  by  Order  of  the  Committee 
of  Public  Safety  —  —  —  —  —         p,  64 

Combuftibility  of  iron.  Reduftion  by  charcoal.  Combination  of  both.  Crude  iron  ;  white  and 
grey.  Forged  iron.  Steel.  Natural  fteel — how  manufaiEtured.  Steel  by  cementation ;  defcrip- 
tion  of  the  procefles  for  making  it. 

IV.  Obfervations  chemical  and  economical  on  various  Subjefts      —     P-  71 

Mutual  aftion  of  nitrous  and  hydrogen  gas.  The  urine  of  animals  which  feed  on  vegetables  does 
not  contain  phofphoric  but  benzoic  acid.  On  wooden  bellows  and  the  blowing  cylinders  of 
iron.     Separation  of  fea  fait  by  fpontaneous  evaporation. 

V.  An  Analylis  of  the  earthly  Subftance  from  New  South  Wales,  called 
Sydneia,  or  Terra  Auftralis.     By  Charles  Hatchett,  Efq.  F.  R.  S.        p.  72 

E.xamination  of  two  fpecimens  of  the  Sydney  Earth,  obtained  from  Sir  Jofeph  Banks  ;  one  of  which 
was  part  of  the  very  parcel  formerly  examined  by  Wedgwood.  They  did  not  exhibit  the  peculiar 
properties  announced  by  that  chemift,  and  were  found  to  contain  much  (ilex,  with  alumine,  car* 
bonet  of  iron,  and  3  fmall  portion  of  water,  or  volatile  matter,  but  no  other  fubftance.  The 
Sydney  earth  muft  confequently  be  rejefted. 

VI.  The  Method  of  making  ftrong  artificial   Magnets.      By  M.  Coulomb 

p.  80 

Method  of  the  double  touch.  Improved  by  .^pinus.  Particular  inflruftions  for  the  method  of  M. 
Coulomb. 

VII.  On  the  Separation  of  Argillaceous  Earth  from  Magnefia.  By  Mr.  F. 
Accum  —  —  —  — ■  —  —        P-  ^3 

Carbonate  of  ammoniac  totally  feparates  the  clay  from  a  faturated  marine  folution,  containing  that 
earth  and  magnefia. 

VIII.  Extrafts  from  the  Manufcripts  of  Leonard  de  Vinci.  With  Remarks 
by  J.  B.  Venturi,  Profeffor  of  Natural  Philofophy  at  Modena,  Member  of 
the  Inftitute  of  Bologna,  Sic.  —  —         • —  —     p.  84 

On  the  defcent  of  heavy  bodies  combined  with  the  rotation  of  the  earth.  Hiftorical  documents. 
Experiment  to  fliew  the  earth's  rotation.  General  effefts  of  gravitation.  Lunar  aftronoray.  Cir- 
culation of  the  ocean  by  heat.  Theory  of  the  earth.  Combufli6n.  Statics.  Enumeration  ,^of 
the  caufes  which  influence  the  quantities  of  water  ifluing  from  an  orifice.  Law  of  circular  ed- 
dies in  water.  On  viiion.  Military  architefture.  Various  iuftruments.  The  Greek  fire.  Pure 
oil  by  maceration.     Obfervations  on  method,  &c. 

IX.  Obfervations  and  Experiments  on  the  Formation  of  Sulphate  of  Soda, 
or  Glauber's  Salt,  in  Salt  Waters,  at  a  Temperature  beneath  the  freezing 
Point  of  Water,  and  upon  an  eafy  Method  of  difengaging  ail  the  dilique- 
fcent  Salts.     By  M.  Green  —  —  —  P- 9^ 

Sulphate  either  of  alumine  or  of  magnefia  decompofe  common  fait,  if  at  a  temperature  below 
freezing.  Methods  of  clearing  falt-water  of  every  foreign  fait,  but  fulphate  of  lime,  which  is 
not  hurtful  to  the  fubfequcnt  procefs. 

ji.,  A 


contents/.  V 

X-  A  Report  made  to  the  Council  of  Trade  and  Mines  in  Spain,  on  a  new- 
Kind  of  Wood,  for  dyeing,  named  Paraguatan.  By  D.  Dominique  Gracia 
Fernandez,  Infpeftor  of  Coinage  —  —  —        P-  93 

Examination  of  Paraguatan  with  acids,  alkalis,   alum,  and  other  reagents,  and  in  dyeing  proccfles. 
Its  great  utility. 

Scientific  News  —  —  —  —  P-  94 

The  government  of  France  offer  for  fale  the  paintings,  &c.  of  Italy.     Account  of  the  fociety  of 
civil  engineers. 


JUNE     1798. 

I.  Abflraft  of  a  Memoir  on  Camphor  and  the  Camphoric  Acid,  read  to  the 
Firft  Clafs  of  the  National  Inllitute  of  France.     By  Bouillon  La  Grange 

P-97 

Hiftoiical  fafts.  Procefles  for  decompofing  camphor — by  deftniftive  diflillation  with  clay — and 
wiin  aliimine.  About  one-third  comes  over  in  the  form  of  a  volatile  oil,  aromatic,  yellow,  eva- 
porable,  combinable  with  alkali,  with  alcohol,  affording  no  precipitate  by  oxygenated  muriatic 
acid.  Carboiie  lemains  in  the  retort,  apparently  combined  with  the  alumine.  Attempt  to  combine 
a  volatile  oil  witn  carbone. 

II.  Infl:ru£\ions  concerning  the  Manufacture  of  Steel,  and  its  Ufes.  By  Van- 
dermondis  JMonge,  and  Berthollet.  Publilhed  by  Order  of  the  Committee 
of  Public  Safety.     Concluded  from  Vol.  ii.  p.  70         —         —         p.  102 

Procefs  for  m?king  c.  fl-fleel  at  Sheffield.  Properties  of  the  different  kinds  of  fleel.  Method 
of  diftinguillnng  itecl  from  iron  by  a  drop  of  weak  acid.  Whether  carbone  be  the  only  addition 
to  iron  in  ine  Heel-making  procefs.  Obfervations  on  hardening  fteel.  Manufaflure  of  fleel- 
rollers.  Dft;  adanon  of  fteel  and  of  cafl-iron  in  the  fire.  Simple  fufion  with  a  viireous.flux  will 
not  atford  the  Englilh  cafl-fteel.     Difference  between  tenacity  and  hardnefs. 

III.  An  Enquiy  concerning  the  Source  of  Heat  which  is  excited  by  Fri6lion. 
By  benjamin  Count  of  Rumford,  F.  R.  S.  M.  R.  I.  A..        —  p.  106  • 

Great  heat  produced  in  boring  brafs  cannon.  Enquiry  whence  itcomes.  Experiment  Ihews  that 
the  capacity  of  the  metalhc  chips  for  heat  is  not  altered  by  the  procefs.  Defcription  of  an  appa- 
ratus in  which  heat  was  produced  by  the  flrong  friftion  of  a  blunt  borer  againft  the  bottom  of 
a  cylindrical  cavity  in  a  mafs  of  metal.  Admeafurement  of  the  heat.  Repetitions  of  the  experi- 
ment, in  which  the  air  was  prevented  from  communicating  with  the  rubbed  furface.  The  opera- 
tion being  performed  under  water,  caufed  two  and  a  quarter  gallons  of  that  fluid  to  boil.  Eflimate 
of  the  total  quantity  of  heat  which  was  generated  and  of  the  number  of  wax  candles  which  would 
have  afforded  the  fame  quantity  in  the  fame  time.  Reflexions  on  the  confequences  to  whicii 
thefe  experiments  appear  to  point  refpefting  the  exiflence  of  an  igneous  fluid  or  matter  of  heat. 

"VI.  An  Attempt  to  difcover  the  Genuinenefs  and  Purity  of  Drugs  and  Me- 
dical Preparations.     By  Frederick  Accum         —        —        —      p.  118 

Examination  of  faline  fubftances.  Sulphuric,  nitrous,  acetic,  acetous,  boracic,  tartareous,  karabic 
and  benzoic  acids. 

V.A 


VI 


CONTENTS. 


V.  A  Model  propofed  for  the  Conftruftion  of  a  Satellitian,  or  Inftrument  for 
explaining  the  Phenomena  of  Jupiteir  and  his  Satellites,  with  an  Account 
ofitsUfe.     By  the  Rev.  W.  Pearfon,  of  Lincoln        —  —       p.  laz 

Conftniftion  of  the  inftrument.  Reftification.  Caufes  of  irregularity  in  the  movements  of  Jupi- 
ter's fatellites.     Enumeration  of  phenomena  difplayed  by  the  fatellitian.     General  remarks. 

VL  Objeftions  to  the  Opinion  of  Profeflbr  Spallanzani  refpe£i:ing  the  Caufe 
of  the  Light  of  Natural  Phofphori,  Communicated  to  Mr.  John  Fab- 
broni,  Sub-dire£lor  of  the  Royal  Mufeum  of  Florence.  By  M.  Joachim 
Carradori,  M.  D.     .        —  —  —  .         —  —     P-  132 

Scheele  was  the  firft  difcoverer  that  water  abforbs  oxygen  from  the  atmofphere.  Glow-worms,  lu- 
minous fliesj  and  fhining  wood,  give  light  under  water,  under  oil,  and  in  the  barometric  vacuum. 
Luminous  flies  in  oxygen :  various  obfervations  and  enquiries. 

VII.  Sketch  of  the  Hiftory  of  Sugar,  in  the  early  Times,  and  through  the 
middle  Ages.     By  W.  Falconer,  M.  D.  F.  R.  S.  &c.  &c.  p.  136 

The  fweet  cane  mentioned  as  an  article  of  commerce  by  Ifaiah  and  Jeremiah.  Various  accounts  of 
fugarfrom  authors  before  Chrift.  Artificial  preparation  lirft  mentioned  about  A.  D.  80,  but  doubt- 
fully ;  certainly  as  a  general  praftice  about  Tripoli,  in  Syria,  in  1108. — Other  authorities  down  to 
the  year  1170. 

VIII.  Experiments  and  Obfervations  on  the  Effe£l:  of  annealing  a  Plate  of 
Metal,  confifting  of  fine  or  alloyed  Gold,  with  one  twenty-fourth  Part  of 
Tin.     By  Mathew  Tillet        —  —  -^  —        p.  140 

Account  of  Mr.  Alcorne's  Paper  in  the  Philof.  Tranf.  for  1764,  in  which  it  is  flated,  the  tin  impairs 
the  malleability  of  gold  very  little,  and  that  the  univerfal  opinion  to  the  contrary  was  probably 
founded  on  the  prefence  of  arfenic.  Preparatory  experiment  with  fine  gold  and  -^'^th  tin,  which 
proved  confiderably  brittle. 

Accounts  of  Books  —  —  —  —  —     p.  142 

Philofophical  Tranfaftions.     Count  Rumford's  Effays.     Sheldrake  on  the  Club  Foot,  &c. 


JULY    1798. 

I.  Memoir  on  a  New  Metallic  Acid  which  exifts  in  the  Red  Lead  of  Siberia. 
By  Vauquelin  —  —  —  —  p,  145 

The  red  lead  ore  boiled  with  carbonate  of  potafli  affords  the  carbonate  of  lead,  and  a  fait  which  was 
decompofed  by  nitric  acid,  and  afforded  a  peculiar  acid.  The  fame  ore  gives  its  lead  to  diluted  mu- 
riatic acid,  while  the  new  acid  is  precipitated  in  a  red  powder.  Charadters  by  which  this  acid  dif- 
fers from  that  of  molybdena,  and  alfo  from  uranium,  titanium  and  tungflen.  It  is  reducible  to  a 
grey,  veiy  hard,  brittle,  eafily  ctyftaliizable  in  fmall  needles,  and  not  readily  acidified  by  nitric 
sicid. 

II.  Far- 


CONTENTS. 


vu 


II.  Farther  Experiments  and  Obfervations  on  the  Affeftions  and  Properties 
of  Light.     By  Henry  Brougham,  jun.  Efq.  —  —       ?•  ^47 

Images  by  reflexion,  inflexion,  and  deflexion  of  homogeneal  light  of  different  fizes  according  to  the 
diftance  to  which  bodies  aft  on  the  particles  of  light.  Phenomena  explicable  on  this  principle. 
Colours  in  tranfparent  plates — in  metallic  fpecula — and  in  lenfes,  in  confequence  of  minute  imper- 
feftions. 

III.  Enquiries  refpefting  the  Colouring  Matter  of  Vegetables,  and  the  A£tion 
of  Metallic  Subftances  and  their  Oxydes  upon  them ;  together  with  a  New 
Procefs  for  obtaining  Lakes  of  the  moft  intenfe  and  folid  Colours.  Read 
to  the  National  Inftitute  (of  France)  15  Vendemiare,  in  the  Year  VI.  By 
the  C.  Guy  ton  —  —  —  —  P-  ^55 

Theory  of  the  red  colours  of  vegetables.  The  aftion  of  tin,  or  its  oxyde,  confifts  in  feizing  the  acid 
of  the  red  compound.  Other  metals  prodvfce  the  fame  effeft — but  tungften  moft  eminently,  be- 
caufe  infoluble  in  the  mineral  acids.  Valuable  lakes  from  the  different  vegetable  matters,  particularly 
aloes. 

IV.  Abftraft  of  a  Memoir  on  Camphor  and  the  Camphoric  Acid,  read  to  the 
Firft  Clafs  of  the  National  Inftitute  of  France.     By  Bouillon  La  Grange 

P-  ^S7 

Procefles  for  obtaining  camphoric  acid.  Combuftion  of  camphor  with  oxygenous  gas.  Charadlers  of 
camphoric  acid.     Conclulion. 

V.  An  Account  of  feveral  new  Experiments  on  Heat,  with  occafional  Re- 
marks and  Obfervations ;  and  Conjeftures  refpefting  Chemical  Affinity 
and  Solution,  and  the  Mechanical  Principle  of  Animal  Life.  ByBenjamiri 
Count  of  Rurtiford         —  —  —  —         p.  160 

Prefatory  obfervation.  Ineffeftual  attempt  to  tranfmit  heat  downwards  through  a  thin  flratum  of  oil, 
and  of  mercury,  to  a  protuberance  of  ice.  Conclufion  that  thefe  fluids  do  not  conduft.  Obferva- 
tions on  the  etie'^s  of  heat  and  cold  in  chemical  folutions; — ^whether  all  changes  of  form  may  not 
be  true  fufions  and  congelations,  ice.  Eleftive  attraftions  probably  referable  to  the  mere  effefts  of 
heat.  Water  and  brine  do  not  mix,  but  by  change  of  temperature.  Curious  inference  with  regard 
to  frefh-water  lakes.  Ice  formed  at  the  bottom  of  Water.  Phenomenon  of  ground  ice.  Intenfe 
'  heat  in  the  midft  of  mafl'cs  of  cold  liquids,  and  in  other  circumftances.  Application  to  chemical 
theory.     Mifcellaneous  experiments. 

VI.  An  Account  of  certain  Motions  which  fmall  lighted  Wicks  acquire 
when  fwimming  in  a  Bafon  of  Oil ;  together  with  Obfervations  upon  the 
Phenomena  tending  to  explain  the  Principles  upon  which  fuch  Motions 
depend.  By  Patrick  Wilfon,  F.  R.  S.  Edin.- and  Profeffor  of  Praftical 
Aftronomy,  in  the  Univerfity  of  Glafgow        —  —        —     P-  167 

Defcrlption  of  a  fmall  float  and  wick,  which  when  lighted  circulates  upon  oil.  Other  attendant  phe- 
nomena. Deduftion  of  the  caufe  from  the  expanlion  and  circulation  of  fluids  by  heat.  Other  fafts 
and  experiments. 

VII.  Experimental  Refearches  concerning  the  Principle  of  the  lateral  Com- 
munication of  Motion  in  Fluids,  applied  to  the  Explanation  of  various 

Hydraulic 


VIU 


CONTENTS. 


Hydranlic  Phenomena.  By  Citizen  J.  B.  Venturl,  Profeflbr  of  Experi- 
mental Philofopliy  at  Modena,  Member  of  the  Italian  Society  of  the  Infti- 
tute  of  Bologna,  the  Agrarian  Society  of  Turin,  &c.  —  P-  172 

Apparatus  defcribedi — Newton's  general  affirmation  concerning  the  lateral  motion  of  fluids,  does  not 
apply  to  a  jet  at  the  I'urface  of  ftill  water.  Experiments  fliewing  that  the  adjacent  fluid  is  carried 
along  with  the  ftream.  On  the  contrafted  part  of  a  jet. '  The  efflux  is  increaled  by  fuffering  the 
ftream  to  pafs  through  an  additional  tube  in  any  direftlon  whatever  This  increafe  is  in  all  the 
cafes  owing  to  the  prefliire  of  the  atmofphere.  Experiments  ;  by  admitting  the  atmofphere  into  the 
tube ; — by  a  kind  of  barometer; — and  by  an  apparatus  in  vacuo  On  the  expenditure  through  ver- 
tical additional  tubes.  It  is  the  lame  as  correfponds  with  the  height  of  the  tiuid  above  the  lower 
extremity  of  the  tube.  Proof.  Experiments  with  fimple  apertures,  verticle  tubes,  and  horizontal 
tubes.     Efie£ls  of  frittion ;  and  of  vifcidity. 

VIII.  Experiments  and  Obfervations  on  the  EfFe£l  of  annealing  a  Plate  of 
Metal,  confining  of  fine  or  alloyed  Gold,  with  one  Twenty-fourth  Part  of 
Tin.     By  Mathew  Tillct  —  —  —  P- '79 

Alloy  of  gold  of  32  carats  and  one  twenty-fourth  of  tin  in  large  quantities.  It  proved  rigid,  though 
malleable,  but  falls  to  pieces  in  the  fire  by  a  low  red  heat,  and  confequently  is  unfit  for  gold-workers. 
Various  experiments  chemical  and  mechanical.  Fine  gold  alloyed  with  tin  has  the  fame  defe6l.  It 
ariles  from  the  great  fufibility  of  the  tin. 

IX.  On  the  Knowledge  of  the  Ancients  refpecting  Gravity.  By  a  Corre- 
fpondent  —  —  —  —  —  p.  184 

Quotation  from  Plutarch.    Remarks. 

X.  A  fhort  Mineralogical  Defcription  of  the  Mountain  of  Gibraltar.     By 
Major  Imrie  —  —  —  —  —         P-  185 

Dhnenfions  and  compofitlon  of  the  Rock  of  Gibraltar.  Its  caverns.  Phenomenon  which  fliews  that 
water  formerly  covered  this  rock. 

Account  of  New  Books        —  —  —  —        p.  188 

Memoirs  of  the  Literary  and  Phllofophlcal  Society  at  Maiichefter,  Vol.  V.— Tranfaftions  of  the  Royal 
Society  of  Edinburgh,  Vol.  IV. 


AUGUST     1798.  ■ 

Engravings  of  the  following  Objefts  :  i.  An  Economical  Laboratory,  by  Guy- 
ton.  2.  Sketch  of  the  Gold  Mine  in  the  County  of  Wicklovv,  in  Ireland. 
3.  A  very  fimple  Apparatus  for  performing  the  Combuftion  of  Oxygen  and 
Hvdrogen,  by  Cuthbcrtfon.  4.  A  New  Steam  Engine,  operating  by  the 
joint  Powers  of  Steam  and  the  Atmofpheric  PrefTure,  by  James  Sadler, 
£fq.  . 

I.  Far- 


CONTENTS.  ix 

I.  Farther  Experiments  and  Obfervations  on  the  Aflfefllons  and  Properties  of 
Light.     By  Henry  Brougham,  jun.  Efq.  —  —        —     P- ^93 

Oa  the  colours  produced  by  the  irregularities  of  fpecula  of  metal  and  of  glafs,  &c. — Conclufion. 
Phenomena  of  Iceland  ciyftal,  not  produced  by  refraftion  or  flexion.  Conjefture  refpefting  it. 
General  propofilions. 

II.  Obfervations  on  Bituminous  Subftances,  with  a  Defcription  of  the  Varie- 
ties of  the  Elaftic  Bitumen.  By  Cliarles  Hatchett,  Efq.  F.R.S.  Load, 
and  Edin.  F.L.S.  &c.  —  —  ■—  —  p.  201 

Enumeration  and  defcriptions  of  bitumens  j  naptha;  petroleum;  mineral  tar;  mineral  pitch;  af- 
j^  phaltum  ;  jet ;  pit-coal ;  bituminous  wood  ;  turf;  peat ;  and  bituminous  ores.  Gradations  from 
naptha  to  afphaltum  occafioned  by  the  proportion  of  carbone  becoming  greater  in  confequence  of 
the  efcape  of  other  principles.  The  flow  combuftion  of  pit-coal  depends  not  only  upon  the  nature- 
of  the  component  parts,  but  the  intimacy  of  their  union.  Fafts  and  obfervations  rcfpefting  bitumi- 
nous wood,  turf,  and  peat,  and  the  developement  of  carbonej  in  vegetable  matter^  during  the  change 
it  undergoes  in  the  bowels  of  the  earth. 

III.  New  Methods  of  affording,  at  an  inconfiderable  Expence,  the  Heat  and 
tlie  Water  required  for  performing  Experiments  in  Chemiftry.  By  Citizen 
Guyton  —        —  — ■  —  . —  p.  209 

,  Great  advantage  of  fimplicity  in  experiments  exemplified  in  thofe  of  Franklin  and  Bergman.  De- 
fcription of  a  very  ufeful  lamp  furnace.  Almoft  every  operation  in  chemiflry  performed  by  this 
apparatus  with  great  fpeed,  precifion  and  perfpicuity.  Inftances.  Pure  water  an  objeft  of  the 
firit  neceffity  in  chemical  refearches.  Many  experiments  are  neglefted,  or  inaccurately  performed, 
for  want  of  a  fufficient  quantity  of  this  fluid.  Rain  water  coUefted  from  the  roofs  of  houfes  after 
the  firft  {hower  has  waflied  the  furface,  contains  no  impurity  but  phofphate  of  lime,  and  a  portion 
of  earthy  matter  mechanically  fufpended.  The  latter  is  removed  by  immediate  filtration,  and  the 
former  by  a  Iblution  of  pure  barytes.  This  earth  forms  an  inibluble  precipitate  with  the  fulphuric 
acid,  and  leaves  the  lime  partly  dilTolved  ;  which  likewife  falls  down  by  abforption  of  carbonic  acid 
from  the  atmofphere,  or  by  the  defigned  addition  of  a  portion  of  pure  water  impregnated  with  that 
principle.  The  depuration  of  water  by  barytes  promtfes  to  be  of  great  utility  in  the  art  of  dyeing 
and  other  proceffes. 

IV.  An  Account  of  fome  Experiments  made  by  Mr.  John  Cuthbertfon,  with 
a  View  to  determine  an  unequivocal  Method  of  afcertaining  the  Power  of 
Eledrical  Machines      .  —  —  —  —         P-2i5 

Meafures  of  ele61ricity,  by  the  fiiark,  by  the  charge,  and  by  attrailion.  Inconveniences  of  each. 
Modifications  of  the  rule  for  eftimating  eleftrical  charges.  New  method  of  mealiiring  eleftricity  by 
the  explofion  of  wire.     Experiments.      '     " 

V.  Mincralogical  Defcripticjjgi  j^f  G.ibraltar.     By  Major  Imrie.  (Concluded.) 

,  '''\^:'".:i  ,V.  p.  2.19 

Obfervations. — Account  of  the  foflil  bones  found  in  the  Rock  of  Gibraltar.     Their  origin. 

VI.  Accounts  of  the  Difcovery  of  Native  Gold  in  Ireland         —  p.  223 

Situation  of  the  gold  mine,  Hlftorical  fafts  refpcifling  it.  Mineralogy  of  the  country.  Particular 
account  of  the  auriferous  ftream,  the  wtn-lungs,  and  the  late  produce.  ".c  ,)'i/.l 

.  Vol.  II. — March  1799.  «  VIK'Ka 


X  CONTENTS. 

VII.  An  Account  of  the  Principles  and  EfFe£l  of  Steam  Engines,  which  a£l 
by  Means  of  a  Pifton.  With  Defcriptions  of  the  Atmofpherical  Engine 
of  Newcomen  and  Cawley,  the  Engine  of  Watt,  which  works  in  Vacuo  ; 
and  a  new  Engine  by  Mr.  Sadler,  m  which  the  direft  Aftion  of  Steam  and 
the  Preflure  of  the  Atmofphere  are  combined         —  —  p.  22S 

Familiar  defcription  of  the  fteam-engine  of  Newicomen  and  Cawley  j  and  of  Watt  and  Boulton^ 
Defcription  and  principles  of  Mr.  Sadler'a  (team  engine. 

VIII.  On  the  fuppofed  Improvement  of  Achromatic  Lenfes,  when,  rendered 
more  tranfparent  by  cementing  them  together         —  —     ?•  ^33 

Caufe  of  the  obfciirity  and  mifty  appearance  of  objefts  through  achromatic  lenfes.  Remedy  by  tb«  in- 
terpofition  of  water,  and  of  maftic.  Approved  by  feveral  eminent  French  philofophers.  Experiment 
by  W.  N.  Mr.  Ramfden's  account  of  a  compound  lens  cemented  together.  The  aberrations  are 
greatly  increafed  by  this  treatment,  and  the  lens  rendered  lefs  perfeft. 

IX.  Defcription  of  a  very  fimple  Apparatus  for  performing  the  great  Ex- 
periment of  producing  Water  by  the  Combuftion  of  Hydrogen  Gas,  In-. 
vented  by  Mr.  John  Cuthbertfon  —  — ■  —         P- ^35 

Scientific  News  —  —  —  —       p«  236 

Account  of  the  public  fitting  of  the  National  Inftitute  of  Sciences  and  Arts,  held  at  Paris,  July  3, 
1798. 

Mr.  Dodd's  projeft  and  eftimate  for  a  tunnel,  or  fubtcrraneous  road,  under  the  Thames,  from  Grayef. 
end  to  Tilbury.     Remarks. 

Particulars  of  Dr.  Herfchel's  difcovery  of  four  newfatellites  to  the  Georgium  Sidus.  The  old  fatellites 
move  in  a  retrograde  direftion,  Surmife  of  two  rings;  and  obfervation  of  the  oblate  figure  of  this 
primary  planet. 


SEPTEMBER    1798. 

Engravings  of  the  following  Objefts :  i.  An  Apparatus  for  Bleaching  by  the 
Oxygenated  Marine  Aci<i ;  and,  «.  An  Artificial  Overflowing  Well. 

I.  Experiments  on  Carbonated  Hydrogenous  Gas,  with  a  View  to  determine 
whether  Carbon  be  a  Simple  or  a  Compound  Subftance.     By  Mr.  William 

•   Henry  —  —  —  —  —         p.  241 

Hxpanflon  of  carbonated  hydrogenous  gas  by  eleftrization,  obferved  by  Dr.  Auftin.  Conclufion  that 
hydrogen  is  evolved  :  Queftion,  whether  this  comes  from  the  carbon  ?  Obfervations  and  experi- 
ments to  fliew  that  water  is  decompofed,  and  not  the  carbon ;  which  muft,  therefore,  ftill  be  con- 
fidered  as  an  elementary  fubftance. 

II.  Obfervations  on  Bituminous  Subftances,  with  a  Defcription  of  the  Va- 
rieties of  the  Elaftic  Bitumen.  By  Charles  Hatchett,  Efq.  F.R.S.  Lond. 
and  Edin.  S.L.S.  &c.  —  —  —  — '  P-  248 

Trodu£tion  of  bitumens.  New  fpecies  found  in  Derbyfliire,  which  is  elaftic.  Enumeration.  Ex- 
xerimcnts  and  obfervations  on  this  fubftance. 

III.  Ob- 


CONTENTS. 


Xi 


III.  Obfervations  on  the  Phyfical  and  Political  Geography  of  North  Africa. 
By  James  Rennel,  Efq.  F.R.S.  —  —  — ,         P«  253 

Dlvifion  of  North  Africa  into  three  parts,  namely,  the  Northern,  the  Tropical,  and  the  Defert  Re- 
gions. General  view  of  the  Defert.  Phyfical  and  political  notices  concerning  the  tropical  region  or 
Taft  belt  of  elevated  land  in  the  parallel  of  10*  north. 

IV.  Obfervations  on  Metallic  Money ;  chiefly  directed  to  afcertain  the  raoft 
advantageous  Diftribution  and  Figure  of  Gold,  Silver,  and  Copper,  in 
Coins  —  .  —  —  —  —  p.  260 

Political  Economy.  How  the  commercial  Intercourfe  of  fociety  is  facilitated  by  money.  New  Britifli 
coinage  in  contemplation.  Metallic  money.  The  ratio  of  value  between  different  metals  cannot 
be  fettled  by  the  State.  Hence  the  national  medium  ought  to  be  of  one  metal  only,  namely,  gold ; 
with  the  lefs  valuable  metals  for  fraftions.  Adjuftment  of  the  relative  values  of  thefe  laft.  De- 
ftruftion  of  coin  by  wear — depends  on  the  material  and  the  figure.  Inveftigation  of  the  bed  figure, 
Obfervations  and  fafts  refpe&ing  the  figure  and  wear  of  guineas.     General  refults. 

V.  An  eafy  Method  of  Cleaning  and  Bleaching  Copperplate  Impreflions  or 
Prints,  extrafted  from  a  Letter  of  Sig.  Geo.  Fabbroni,  Sub-dire6tor  and 
Superintendant  of  the  Royal  Cabinet  of  Philofophy  and  Natural  Hiftory 
of  his  Royal  Highnefs  the  Grand  Duke  of  Tufcany,  to  Sig.  D.  Luigi  Tar- 
gioni  at  Naples  —  —  —  —  p.  265 

InftruiSions  for  preparing  the  oxygenated  marine  acid  by  fimple  mixture,  and  for  blaiching  old  prints 
■with  fafety  and  efFeft. 

VI.  On  the  Propagation  of  the  Zebra  vi'ith  the  Afs        —        —        p.  267 

VII.  On  the  Procefs  of  Bleaching  with  the  Oxygenated  Muriatic  Acid  ;  and 
a  Defcription  of  a  New  Apparatus  for  Bleaching  Cloths  with  that  Acid 
diflblved  in  Water,  without  the  Addition  of  Alkali.  By  Theophilus  Lewis 
Rupp  —  —  _-  —  —        p.  268 

Experiments  which  prove  that  the  ufual  addition  of  allcali  to  the  bleaching  liquor  impairs  its  power. 
Apparatus  for  performing  the  procefs  without  alkali;  by  which  a  favingof  forty  per  cent,  is  gained. 

Vni.  Experimental  Refearches  concerning  the  Principle  of  the  lateral 
Communication  of  Motion  in  Fluids,  applied  to  the  Explanation  of  vari- 
ous Hydraulic  Phenomena.  By  Citizen  J.  B.  Venturi,  Profeflbr  of  Expe- 
rimental Philofophy  at  Modena,  Member  of  the  Italian  Society  of  the  In- 
ftitute  of  Bologna,  the  Agrarian  Society  of  Turin,  &c.  (Continued  from 
p.  179)  —  —  —  _  _        p.273 

Experiments  on  the  qbantitj'  and  limits  of  the  increaled  expenditure  of  fluids  through  conical  diTergent 
*«bes. 

IX.  An  Account  of  the  Means  employed  to  obtain  an  Overflowing  Well. 
By  Mr.  Benjamin  Vulliamy  —  —  —         p.  276 

A  well  of  four  feet  diameter  was  funk  and  fteined  to  the  depth  of  236  feet,  and  then  bored,  and  a 
copper  pipe  of  the  diameter  of  5^-  inches  driven  through  21  feet.     Water  ai^d  fand  rofe  through 

c  a  96  feet» 


xii  CONTENTS. 

96  feet.  The  water  was  drawn  off,  and  the  fand  dug  out,  till  only  36  feet  remained  ;  when  fand 
and  water  again  rufiied  in  to  the  former  height.  The  current  of  water  was  then  continued  by- 
pumping,  and  part  of  the  fand  raifed  through  the  water  by  heavy  valve  buckets.  During  this  laft 
procefs  the  water  gradually  role  and  increafed  in  quantity  fo  as  to  overflQW  the  top  at  the  rate  of 
46  gallons  per  minute. 

Scientific  NewSj  and  Accounts  of  Books  • —  • —  p.  279 

Compofition  for  extinguiftiing  fire. — Travels  in  Africa  by  Mr.  Mungo  Park. — Proceedings  of  the  Afri- 
can Aflbciation — Account  of  Mr.  Park's  route  and  dlfcoveries. — Table  for  reducing  Englifti 
meafures  and  weights  into  French. — ^Table  of  the  prices  of  neceflaries,  day-labour,  &c.  fince  the 
Conqueft.     By  Sir  George  Shuckburgh  Evelyn,  Bart.  F.  R.  S.  and  A.S. 


OCTOBER     1798. 

Engravings  of  the  following  ObjeSls:  i.  The  Art  of  Speedy  and  Swift  Intel- 
ligence.    2.  Sir  R.  L.  Edgeworth's  Portable  Telegraph. 

I.  Curious  Circumftances  upon  which  the  Vitreous  or  the  Stony  Characters 
of  Whinftone  and  Lava  refpeflively  depend  ;  with  other  Fafts.  In  an  Ac- 
count of  Experiments  made  by  Sir  James  Hall,  Bart.  F.R.  and  A.S. S. 
Edin.  —        —  —  —  —  —        p.  285 

Objeftion  to  the  igneous  formation  of  whihftone  or  bafaltes,  which  by  fufion  affords  glafs.  Di(^ 
covery  that  the  vitreous  character  is  owing  to  fpeedy  refrigeration,  and  that  the  ftony  charaifterwith 
a  lefs  degree  of  fufibility  is  afforded  by  flow  cooling.  Valuable  induftions,  with  a. table  of  the  ra- 
fuHs  of  experiment. 

II.  On  the  Analyfis  of  Pumice,  which  is  found  to  contain  Potafli ;  and  of 
Bafaltes  and  Lava,  containing  Soda.     By  Dr.  Kennedy  —        p.  289^ 

III.  Experiments  and  Obfervatlons  on  the  Preparation,  and  fome  remarkable 
Properties,  of  the  Oxygenated  Muriate  of  Potafli.  By  Mr.  Thomas  Hoyle, 
jun.  —  —  —  —  —  p.  290 

Preparation  of  the  oxygenated'muriate  of  potafli,  and  its  foltition  in  water  and' acids.  Effeflis  of  light 
and  heat.  Detonation  with,  a  great  number- of  combutlible  fubftances  with  the  fait  by  friAioH  and 
the  acids. 

IV.  Obfervations  on  the  Natural  Hiftory  of  Guiana.  In  a  Letter  from  Wil^ 
liam  Lochead,  Efq.  F.R.S.  Edin.  to  the  Rev.  Dr.  Walker  F.R.S.  Edin. 
Regius  Profeflbr  or  Natural  Hiftory  in  the  Univerfity  of  Edinburgh,  p.  29,7 

Goad  of  Gruinea.     Striking  appearance  of  the  fky — within  the  tropics.     Winds,  dews,  fogs,  and  tem«, 
pemturc.    Face  of  the  country.    Defcription  of  the  Savannahs. 

V.Oh 


CONTENTS. 


XllI 


V.  On  the  Sugar  Maple.     By  Citizen  Teffier        —  — 'p.  304; 

Accounts  of  the  climate  inoft  favourable  to  the  growth  of  fugar-maple  trees.  Method  of  obtaining  the 
faccharine  juice.  Hiftorical  fafts.  Quality  and  quantity  of  maple-fugar  produced  in  Canada.  In- 
ftru6lions  for  introducing  this  tree  into  Europe.  Probable  advantages.  Dr.  Rufli's  account  of  the 
manufafture  of  maple-fugar  in  the  weftern  countries  of  America. 

VI.  The  Progrefs  of  Mechanical  Difcovery,  exemplified  in  an  Account  of  a 
Machine  for  cutting  Files.    (W.  N.)  —  —  p.  309 

Chemical  and  mechanical  purfuits  compared.  The  greater  number  of  new  machines  are  of  no  value. 
Difficulties  of  carrying  inventions  into  elFeft.  Progrefs.  Machine  for  cutting  files.  General  re- 
marks. 

VII.  The  Dutch  Procefs  for  making  the  Blue  diftinguiflied  by  the  Name  of 
Turnfol  —  —  —  —         —         P-S^i 

YIII.  Experiments  and  Remarks  on  certain  Ranges  of  Colours  hitherto  un- 
obferved,  which  are  produced  by  the  relative  Polition  of  plain  Glaflfes,  with 
regard  to  each  other.     (W.N.)  —  —  — ;         p.  312 

Short  ftatement  of  Newton's  do6lrine  of  the  fits  of  refleftion  and  tranfmlfiion  of  light.  Subfequent 
experiments.  A  new  feries  of  colours  formed  between  plain  glaffes  ;  ditFerent  from  but  coexiftent 
with  the  Newtonian,  and  much  lefs  affefted  by  changes  of  temperature,  pofition,  or  eleftrization. 
This  efFedt  is  produced  when  the  plates  are  at  confiderable  difiances  from  each  other  j  for  example, 
four  feet.     Other  fafts.. 

IX.  Some  Account  of  the  Country  and  Climate  of  the  North-weftern  Lakes 
of  America.    By  Major  C.  Swan,  Paymafter  to  the  Weftern  Army.   p.  315 

X.  An  Eflay  on  the  Art  of  conveying  Secret  and  Swift  Intelligence.  By 
Richard  Lovell  Edgeworth,  Efq.F.R.S.  and  M.R.I.  A.  —  p.  319 

Defcription  of  the  French  Telegraph,  and  that  of  Robert  Hooke.     Late  trial  of  Hooke's  method»    De- 
fcription  and  ufe  of  an  apparatus  for   fpeedy  and  fwift  communication  by   numbers.     It  fupe-  - 
Viority  over  the  alphabetical  telegraph.     Carried  into  efteft  acrofs  the  Irifli  Channel. 

Scientific  News,  and  Accounts  of  Books  — ■  —  p.  31S 

Mr.' Park's  Travels  in  the  unexplored  Parts  of  Africa      — ■        —        p.  329 


NOVEMBER     1798. 

Engravings  of  the  following  Objefls  :  i.  Leaf,  Acorn,  and  Prickly  Cup  of 
the  Turkey  and  Spanifli  Oaks.  2.  A  new  Efcapement.  And,  3.  An  Apar 
ratus  for  faturating  the  Alkalis  with  Carbonic  Acid. . 

f.  An  Account  of  three  different  Kinds  of  Timber  Trees,  which  are  likely  ^o  - 
prove- a  great  Acquifitioh  to  this  Kingdom,  both  in  point  of  Pro/^t,  and  as 
Trees  for  Oniament  and.Shade,     By  Charles  White,  Efq.,F,R.S.      p..  333, 
...  "  Hiltorical; 


xi^  CONTENTS. 

Hiftorical  h&s  and  obfervations,  which  prove  the  rapid  growth  and  advantages  to  be  derived  from 
the  broad-leaved  American  black  birch,  the  Athenian  poplar,  and  the  iron,  wainfcot,  or  Turkey 
oak. 

II.  Abftradl  of  a  Memoir  of  M.  Prouft,  on  the  Tanning  Principle.  By  Citi- 
zen Defcotils        —  —  —  —  —  P-  537 

The  folution  of  muriate  of  tin  precipitates  the  tanning  principle  from  a  decoftion  of  nut-galls,  and 
leaves  the  acid  of  galls  in  folution.  Methods  of  obtaining  the  gallic  acid  and  the  tanning  principle 
feparate  from  each  other.  Precipitate  of  glue  with  tanning.  The  green  fulphate  of  iron  is  not  pre- 
cipitated by  either  of  the  principles  of  galls.  Difference  of  the  precipitates  of  the  red  fulphate  by 
thofe  principles.     Application  of  the  fafts  to  the  procefs  of  dyeing  black. 

HI.  Notice  of  a  Memoir  of  Citizen  Guy  ton,  upon  the  Tables  of  the  Compofi- 
tion  of  Salts,  and  the  Means  of  verifying  the  Proportions  indicated  by  thofe 
Tables  —  —  —  —  p.  340 

When  two  falts,  differing  in  their  acids  and  their  bafes,  are  of  fuch  a  nature  as  to  change  their  prin- 
ciples by  double  eleftive  attraction,  as  for  example,  the  fulphate  of  potafh  and  nitrate  of  lime,  it  is 
known  that  two  new  falts  are  formed  ;  namely,  In  the  prefent  inltance,  nitrate  of  potafh  and  ful- 
phate of  lime  :  but  the  quantities  of  each  bafe,  fufficient  to  produce  neutral  falts  in  the  firli:  combi- 
nations, are  not  the  fame  as  will  faturate  the  acids  in  the  new  compounds.  If,  therefore,  the  quan- 
tity of  one  fait  be  fuch  as  to  afford  enough  of  its  bafe  to  faturate  the  acid  of  the  other,  the  bafe  of 
this  lafi  will  be  either  more  or  lefs  than  is  fufficient  to  faturate  the  acid  of  the  firit-mentioned  lalt. 
In  this  cafe,  it  may  be  inferred,  that  one  of  the  new  compounds  will  be  neutral,  and  the  other  not 
fo.  But  the  fafts  refute  this  conclufion  ;  for  the  mixture  fliews  no  redundance  of  either  principle. 
Why  this  happens  is  a  new  and  interefting  chemical  theorem. 

IV.  On  Pafigraphy ;  or,  the  Art  of  Writing  which  fhall  be  intelligible  to  all 
Nations         —  —  —  —  —        p.  342 

The  univerfal  writing  is  not  the  means  of  rendering  all  languages  intelligible  to  all  nations ;  in  its  own 
nature  it  fuppofes  the  exiflence  of  one  common  language  propofed  to  all  nations  for  their  acceptance 
and  ufe.     Hiftory  of  the  attempts  and  obfervations  of  various  eminent  men  ;  Lord  Bacon,  Des 

•Caftes,  Becher,  Dalgani,  Frifichius,  Kircher,  Befnier,  Wilkins,  Leibnitz,  Dc  I'Epfee,  and  Condillac. 

KJeneral  remarks. 

Y,  Obfervatioiis  on  the  Natural  Hiftory  of  Guiana.  In  a  Letter  from  William 
Lochead,  Efq.  F.R.S.  Edin.  to  the  Rev.  Dr.  Walker,  F.R.S,  Edin.  Regius 
Profeffor  of  Natural  Hiftory  in  the  Univerfity  of  Edinburgh        —       p.  347 

•Obfervations  on  the  rivers,  and  their  agency  in  forming  the  foil,  of  Guiana ;  their  creeks,  floods, 
tides,  &c. 

VI.  On  the  fiippofed  Revival  of  Infcdts  after  long  Immerfion  in  Wine  or  other 
intoxicating  Liquor.     By  Mr.  John  Gough  —  —  p.  353 

Sfetperiments  on  various  infers,  which  prove  that  the  popular  notion  of  their  revival  many  months 
after  their  immerfion  in  fermented  liquors  is  ill  founded. 

VII.  Various  Notices  rcfpefting  the  Arts  in  Turkey. — Jeweller's  Foil. — Glue,  or' 
Maftic  for  S:ones  and  Metals. — Calling  of  Malleable  Iron. — Filtration  by 
Afccnt. — Butter  prefer ved  without  Sale. — Extemporaneous  Yeaft         p«355 

VIII.  Ob- 


CONTENTS.  J  ■       xr 

VIII.  Obfervadon  of  the  Paflage  of  a  Comet  over  the  Difc  of  the  Sun.  By  Citi- 
zen Dangos  —  —  —  —  P*  357 

Time  and  duration  of  the  phenomenon.    Inferences^    Why  comets  cannot  be  often  fcen  on  the  face  of 
the  fun, 

IX.  Analyfis  of  the  Aqua-marine  or  Beryl ;  and  the  Dlfcovery  of  a  new  Earth  in 
that  Stone.  Read  before  the  French  National  Inftitute  26  Pluviofc,  in  the 
Year  VI.    (Feb.  14,  1798.)     By  Citizen  Vauquelin  —  P  35^ 

Method  of  Analyfis.  New  earth,  foluble  in  acids  and  in  pure  potafh;  and  affording  falts  of  a 
faccharine  tafte.  Comparativi^  examination  of  its  habitudes,  and  thofe  of  aiuminCj  from  which, 
as  well  as  the  other  earths,  it  greatly,  differs. 

X.  Defcription  of  a  new-invented  detached  £fcapement  for  Pocket  W^atches,  Sec. 
By  Mr.  John  Prior  —  —  —  P- 3^3. 

XI.  On  Mr.  Cartwright's  Invention  for  rendering  the  Piftons  of  Steam  Engines, 
Pumps,  and  other  Hydraulic  Apparatus,  tight  by  Metallic  Parts,  without  pack- 
ing or  leathering.     (W.N.)  —  —  —  P- 364 

Letter  of  enquiry.  Defcription  of  the  invention.  Theoretic  and  pradical  reafons  why  this  con- 
trivance muft  prove  lefs  effcftual  than  the  nnethods  already  in  ufe. 

XII.  Information  refpedling  the  Zoonic  Acid,  difcovered  by  BertKollet     p.  2^9 

Animal  fubftances,  the  vegetable  gluten^  and  yeafl,  afford  an  acid  of  deftruftive  diftillation,  which 
may  be  faturated  with  lime,  and  the  ammoniac  then  driven  off  by  boiling.     By  the  addition  of 
phofphoric  acid,  and  diflillation  at  the  boiling  heat,  the  lime  will  form  a  phafphate,  and  the  new- 
acid  will  come  over.     Its  charafters. 

XIII.  Hiftorical  Notes  concerning  the  Invention  of  the  Air-pump  with  Metallic 
Valves  ;  the  Neceffity  of  Alkali  to  produce  the  cryftallized  Salt  called  Alum; 
and  the  Eleftrical  Inftrument  called  the  Revolving  Doubkr         —       p.  370 

XIV.  Defcription  of  an  Apparatus  for  faturating  Potafh  and  Soda  with  Carbonic 
Acid.     By  Cit.  Welther  —  —  —  p.  371. 

XV.  Abftraft  of  a  Memoir  of  Klaproth  on  a  new  Metal  denominated  Tellurium. 
Read  at  the  Public  Se/fionof  the  Academy  of  Sciences  at  Berlin.  Jan.  25, 1798 

374 
Hiftory  of  the  difcovery.  The  white  ore  of  gold  is  heated  with  muriatic  acid ;  to  which  the 
nitric  is  afterwards  added.  The  complete  fohuion  is  diluted,  and  pure  potafh  is  added  in  excefs.  A 
fmall  portion  of  iron,  together  with  gold,  fallsdown;  the  reft  is  diffolved  by  the  alkali.  Muriatic 
acid  throws  down  a  white  precipitate.  It  is  the  oxyde  of  tellurium,  and  is  reducible  by  being . 
made  into  a  pafle  with  oil,  and  fubjefted  to  a  gradual  heat.  The  metal  rifes  in  diftillation  like 
mercury.  It  is  white,  fhining,  brittle,  friable,  very  fufible,  combuftible  with  flame,  combinable 
with  mercury,  and  with  fulphur,  foluble  in  acids,  and  in  the. excefs  of  any  alkali ;  not  pre- 
cipitable  by  pruffiate  of  potafh,  &c.  &c. 

Scientific  News,  and  Accounts  of  Books  —  —  —        P*  37^ 

American  Societies.  Aeroftation.  Rumford's  Effays.  Rivard  oa  the  Spherfr  and  Calendar, 
Townfon's  Mineralogy.    Mr.  Parke's  Travels  ia  Africa,  ^  „  , 

'  D  E  C  E  M- 


xti  O   O    N    T    E    N    T    SI 


DECEMBER     1798. 

■^Engravings  of  the  following  Objects:  i.  A  View  of  the  Manfion  of  Rofea- 
penna,  in  Ireland,  deftroyed  in  Confequence  of  the  Change  of  Climate  fup- 
pofed  to  have  taken  Place' in  that  liland  during  theprefent  Century.  2. 
The   powerful  Ele£trical  Machine   of  Rouland,  which  operates  by  the 

;     Friftion  of  Silk. 

J,  Memoir  on  the  GHmate  of  Ireland.     By  the  Rev.  William  Hamilton,  of 

f     Favet,  in  the  County  of  Donegal ;  late  FelloAv  of  Trinity  College,  Dublin  ; 

M.R.I. A.   Correfponding  Member  of  the  Royal  Society  of  Edinburgh, 

&c.        —  —  —  —  —        —         p.  381 

General  opinion  that  the  feafons  of  Ireland  are  confiderably  changed  within  the  memory  of  man  ; 
that  the  winters  are  milder,  and  the  fummers  lefs  warm.  Meteorological  inftruments  do  not  ex- 
hibit all  the  circumflances  which  influence  a  climate.  Recourfe  muft  be  had  to  other  obferva- 
tions.  The  winds  of  Ireland  have,  of  late  years,  blown  with  uncommon  violence  from  the  weft- 
ward.  Their  effefts  are  particularly  marked  on  the  province  of  Uifler.  Interefting  fafts  re- 
fpefting  trees  which  formerly  flourifhed  in  Ireland,  but  cannot  now  withftand  the  rigour  of  the 
feafons.  The  lands  of  the  fea  have  been  driven  with  increafed  violence  on  the  Irifh  coaft.  Iii- 
flances  of  the  fpeedy  deflruftion  of  habitable  places  and  diftriils  from  this  caufe  in  the  Corpora- 
tion of  Bannow,  the  Manfion  of  Rofeapenna,  and  other  deferted  habitations.  Increafing  violence 
of  the  tides  from  the  Atlantic  Ocean. 

II.  Analyfis  of  the  Red  Lead  of  Siberia  ;  with  Experiments  on  the  New 
Metal  it  contains.  By  Citizen  Vauquelin,  lnfpe£tor  of  Ores,  and  Con- 
fervator  of  Chemical  Produ£l:s  at  the  Mineralogical  School     —         p.  387 

Hiftory  of  the  Siberian  Red  Lead  Ore,  and  the  experiments  formerly  made  upon  it.  New  analyfis. 
I.  By  boiling  with  carbonate  of  potafti,  which  precipitated  carbonate  of  lead,  and  formed  a 
neutral  fait  with  the  peculiar  acid  of  the  ore.  Nitric  acid  deprived  this  fait  of  its  alkali,  which 
cryflallizes  by  fpontaneous  evaporation. — Or  otherwife,  s.  diluted  muriatic  acid  being  added  to 
the  ore,  combined  with  the  lead  of  the  ore,  and  difengaged  the  acid.  The  muriate  of  lead 
being  infoluble,  remained  at  the  bottom,  while  the  peculiar  acid  of  the  ore  became  fufpended, 
together  with  a  fmall  redundant  portion  of  marine  acid.  This  laft,  after  decantation,  was  ab- 
flrafted  by  adding  fmall  portions  of  the  oxyde  of  filver,  and  left  a  folution  of  the  acid  of 
chrome.     Its  nature,  properties,  and  combinations. 

III.  Information  refpefting  the  Earth  of  the  Beryl ;  in  Continuation  of  the 
firft  Memoir  on  the  fame  Subjeft.     By  Citizen  Vauquelin         —       p.  393 

Additional  Experiments  by  which  the  component  parts  of  beryl,  and  the  charafteriftic  properties  of 
the  new  earth  difcovered  in  that  ftone,  are  more  correftly  afcertained. 

IV.  Obfervations  on  Eleftncity,  Light,  and  Caloric ;  chiefly  direifted  to  the 
Kefults  of  Dr.  Pearfon's  Experiments  on  Eleftric  Difcharges  through 
Water.     By  a  Correfpondent  —  —  —        p.  396 

Remarks  on  the  very  Joofe  and  inaccurate  notions  of  philofophers  concerning  eleftricity,  light,  and 
caloric.  Animadverfions  on  Dr.  Pearfon's  theory  of  the  decompofition  and  re-produftion  of 
water  by  eJeftricity.     On  the,  materiality  of  heat. 

V.An 


CONTENTS. 


xvii 


V.  An  Enquiry  concerning  the  Chemical  Properties  that  have  been  attributed 
to  Light.     By  Benjamin  Count  of  Rumfor^,  F.R.S.  M.R.I.A.     p.  400 

Doubt  whether  light  operates  chemically  in  any  other  way  than  by  generating  heat.  Experiments 
on  the  vitrification  of  oxyde  of  gold  by  the  heat  of  a  candle ;  and  by  folar  light.  Effeft  of  dilution 
in  rendering  the  particles  more  minute  and  fufceptible  of  elevated  temperature.  Curious  inflance 
of  gold  reduced  by  charcoal  in  the  humid  way  with  folar  light — and  without. 

VI.  Experiments  and  Obfervations  on  the  Nature  of  Sugar,  and  of  Vegetable 
Mucilage.     By  Mr.  William  Cruickfkank,  Chemift  to  the  Ordnance,  &c. 

p.  406 

Chemical  examination  of  fugar,  honey,  fugar  of  milk,  gum  arable,  and  gum  tragacanth.  Refults : 
That  fugar  is  compofed  of  carbon,  hydrogen,  and  oxygen  ; — fugar  of  milk  contains  more  oxygen 
and  much  lefs  carbon  ; — gum  contains  lime  and  azote  as  well  as  the  principles  of  fugar ; — vege- 
table farina  cannot  become  fugar  without  water  and  oxygen  ; — that  neither  fugar,  if  deprived  of 
oxygen,  or  combined  with  other  matters,  nor  pure  vegetable  nor  animal  mucilage,  is  capable  of 
fermentation. 

VII.  On  the  Art  of  covering  Wire  Cloth  with  a  tranfparent  Varnifli,  as  a  Sub- 
flitute  for  Horn ;  and  on  other  Objefts  of  Public  Utility.  By  Alexis  Rochon, 
of  the  National  Inftitute  of  France,  &c.  —  —  p.  412 

Chinefe  manufadhire  of  horn.  Wire  cloth  prepared  for  lanthorns  with  glue ;  and  with  mica. 
New  covering  for  houfes.    Medical  bougies. 

VIII.  On  the  Produftion  of  Nitric  Acid  by  the  Contaftof  Oxygen  very  much 
heated  and  the  Air  of  the  Atmofphere  —  —  P-  4^3 

New  phenomenon  of  nitric  acid  from  manganefe.     Conjedlures  refpefting  it. 

IX.  Analyfis  of  the  Chryfolite  of  the  Jewellers,  proving  it  to  be  Phofphate 
of  Lime.     By  Citizen  Vauquelin         —  —  —  P*  4^4 

The  chryfolite,  being  pulverifed  and  treated  with  fulphuric  acid,  afforded  fulphate  of  lime,  and  the 
phofphoric  acid  was  difengaged.  In  another  experiment  the  lime  was  taken  up  by  muriatic 
acid,  and  precipitated  by  the  oxalic.  From  both  experiments  the  flone  was  found  to  contain 
54  parts  lime,  and  46  phofphoric  acid, 

X.  Account  of  a  fingular  Inftance  of  Atmofpherical  Refraflion.  In  a  Letter 
from  William  Latham,  Efq.  F.R.S.  and  A.S.  to  the  Rev.  H.  Whitfield, 
D.D.  F.R.S.  and  A.S,  —  —  —  —         p.  417 

Uncommon  view  of  the  coaft  of  France  from  Great  Britain  at  the  diftance  of  forty  or  fifty  miles. 
Remarks  and  references  to  fimilar  fa£ls. 

XI.  An  Account  of  EIe£trical  Machines  of  confiderable  Power,  in  which 
Silk  is  ufed  inftead  of  Glafs.     (W.  N.)  —  —  p.  420 

Various  non-<onduftors  ufed  for  the  excitation  of  eleftricity.  Enumeration.  Defcription  of  the 
machines  of  Ingenhoufz,  Walckiers,  and  Rouland,  which  operate  by  the  friftion  of  filk.  Their 
power  of  excitation. 

Vol.  II.— March  1799.  ^  ^^^'  ^^' 


xviii  CONTENTS. 

XII.  Experimental  Refearches  concerning  the  Principle  of  the  lateral  Com- 
munication of  Motion  in  Fluids,  applied  to  the  Explanation  of  various 
Hydraulic  Phenomena.  By  Citizen  J.  B.  Venturi,  Profeffor  of  Experi- 
mental Philofophy  at  Modena,  IVTember  of  the  Italian  Society,  &c.  p.  422 

Comparative  experiments,  Ihewing  the  quantities  of  water  emitted  under  like  circumftances  through 
different  tubes.  Praftical  propofition  of  great  utility,  by  which  the  expenditure  is  more  than 
doubled.    Roman  law  concerning  the  enlargement  of  pipes  for  water. 

Accounts  of  Books,  8ic.  —  ~  —  —         p.  426 

Philofophical  Tranfaflions,  Part  II.  1798. — RoUo  on  Diabetes  Mellitus. — Pajot-des-Charmes  on 
Bleaching. — Chemical  Memoirs  of  Pelletier.— Leybourn's  Tranflation  of  Dr.  Stewart's  Propofi- 
tiones  Geometricae. — Note  refpefting  Dalgarme,  Leibnitz,  Wilkins,  and  the  Univerfal  Charafter. 


JANUARY 


CONTENTS.  xbc 


JANUARY     1799. 

Engravings  of  the  following  Objcfts:  i.  A  New  Inftrument  for  ruling  parallel 
Lines  for  the  Ufe  of  Engravers :  and,  2.  Mr.  Cavendifh's  Apparatus  for  mea- 
furing  the  mutual  Gravitation  of  Bodies,  and  afcertaining  the  Denfity  of  the 
Earth. 

I.  Defcription  of  a  New  Inftrument  for  drawing  equidillant  and  other  parallel 
Lines,  with  great  Accuracy  and  Expedition,  intended  principally  for  the  Ufe  of 
Engravers  j  with  Specimens  of  its  Performance.     By  W.  N.  p.  429 

The  inftrument  confifts  of  two  flat  rulers,  one  of  which  cojifines  tlie  plate,  and  the  other  is  made  to 
fiiift  through  fmall  intervals  by  means  of  a  fcrew  and  gear,  while  it  conftantly  preferves  its  pa- 
rallelifm. 

IL  Memoir  on  the  Climate  of  Ireland.  By  the  Rev.  William  Hamilton,  of 
Favet,  in  the  County  of  Donegal ;  late  Fellow  of  Trinity  College,  Dublin; 
M.R.LA.  Correfponding  Member  of  the  Royal  Society  of  Edinburgh,  &c. 
(Concluded  from  page  386,  Vol.  II.)  —  —  P- 43i 

General  effefts  of  the  weftern  tempefts  on  the  climate  of  Ireland.  The  fummers  are  rendered 
colder,  and  the  winters  milder. — This  equable  temperature  is  favourable  to  animal  and  vegetr 
able  life. — Caufe  of  the  increafed  violence  of  the  wefterly  winds,  deduced  from  the  forefts  of 
Ireland  inparticular,  and  of  Europe  in  general,  having  been  cleared  in  modern  times,  and  the 
land  cultivated, 

III.  Experiments  and  Obfervations  on  Eleftricity — Excitation — The  two 
States — Points  of  Difference  between  the  Aftion  of  weak  and  ftrong  Elec- 
tricities compared  together.     (W.  N.)  —  —  P-  43^ 

Cafcade  of  eleftric  fire  produced  by  cutting  a  hole  in  the  filk  flap  of  the  rubber.  Beautiful  ftar  formed 
by  the  plus  electricity  upon  paper.  Experiments  to  determine  whether  the  glafs  tube  in  Ben- 
net's  eleftrometer  has  any  efFeft  on  the  divergence  of  the  gold  leaf.  Other  enquiries  refpefting 
the  metallic  coatings  and  lize  of  the  head  of  that  inftrument. — Whether  the  electricity  of  con- 
dudors  is  difturbed  according  to  the  fame  law,  by  the  influence  of  an  ele(ftrified  body,  when  the 
power  is  weak,  as  when  it  is  ftrong.  Remarkable  diff^erence  in  the  operation  of  pointed  bodies 
and. flame  in  weak  and  Itrong  eleftricities. — Whether  the  laws  of  attraftion  and  repulfion  be  the 
fame  in  ftrong  eledricity  as  iu  weak. 

iV.  Analyfis  of  the  Red  Lead  of  Siberia  ;  with  Experiments  on  the  new  Metal 
it  contains.  By  Citizen  Vauquelin,  Infpeftor  of  Mines,  and  Confervator 
of  Chemical  Frodufts  at  the  Mineralogical  School.  (Concluded  from  page 
393,  Vol.  II.)  _____  p.  4^,1 

Combinations  of  the  acid  of  led  lead  with  the  alkalis. — Its  reduftion  to  the  metallic  ftate. — Proper- 
ties of  the  new  metal. — Denomination  and  ufes  in  chemiftry  and  the  arts. 

V.  Experiments  to  determine  the  Denfity  of  the  Earth.  By  Henry  Caven- 
diHi,  Efq.  F.R.S.  and  A.S.  ~  _  —  p.  446 

A  wooden  arin  fix  feet  long  was  fufpended  in  a  horizontal  pofition  by  a  flender  wire  forty  inches 
long,  and  to  each  extremity  was  hung  a  leaden  ball  about  two  inches  in  diameter.    To  thefe 

d  a  balls 


«x 


CONTENTS. 


balls,  on  oppofite  fides,  were  prefented  two  larger  balls,  which,  by  their  attradion,  drew  the  arm 
afide.  The  arm,  with  its  balU,  was  ioclofed  in  a  wooden  cafe,  and  the  whole  apparatus  placed 
tK  a  room  adapted  to  this  purpofe,  and  kept  (hut  while  the  obferver  attended  to  the  efFe£t  from 
without,  by  means  of  a  (hort  telefcopo  oppofite  each  end  of  the  bar.  The  power  required  t  draw 
the  arm  afide,  was  afcertained  from  the  time  of  its  free  vibrations,  and  the  denfity  of  the  earth  com- 
puted from  the  comparifon  between  the  effeft  of  its  attraftion  on  the  balls  with  the  efFeift  of  the 
fame  nature  by  which  the  ai  m  was  drawn  from  its  ftationary  pofition.  This  laft  efftti  amounted 
to  about  one  inch  and  a  half  when  a  thin  wire  was  ufed,  and  about  one  third  of  an  inch  with  a 
thicker  wire:  the  deviations  were,  therefore,  very  perceptible.  The  mean  refult  of  the  earth's 
denfity  proved  to  be  5,48  times  that  of  water, 

VI.  An  Inquiry  concerning  the  Chemical  Properties  that  have  been  attri- 
buted to  Light.  By  Benjamin  Count  of  Rumford,  F.R.S.  M.R.I. A. 
(Concluded  from  p.  405.)  —  —  —  p.  4^3 

Reduftion  of  filver  by  means  of  charcoal  in  the  humid  way  under  the  aftion  of  folar  light,  and 
Jikewife  by  the  heat  of  boiling  water  without  light.  Reduftions  of  gold  by  ether  and  folar  light 
— by  etherial  oil  of  turpentine  and  the  heat  of  fteam.  Oxydes  of  gold  and  filver  reduced  by 
olive-oil  in  a  fimilar  procefs.  Remarkable  precipitation  of  the  folution  of  gold  upon  magnefia 
by  folar  light. 

VII.  Some  Account  of  the  Perfian  Cotton-Tree.  By  Matthew  Guthrie, 
M.D.  F.R.S.  &c.  &c.  —  _  __  p.  4^7 

Account  of  various  fpecies  of  cotton,  particularly  the  Perfian  cotton ;  its  cultivation  and  valuable 
qualities. 

VIII.  Fafts  and  Obfervations  concerning  the  Meafure  and  Expence  of  firft 
Movers,  namely.  Wind,  Water,  Steam,  and  Animal  Strength,  and  on  other 
Objefts  of  general  Utility.     (W.  N.)  —  — ■  p.  459 

Great  wafte  of  labour  and  expence  incurred  by  manufaflurers  and  others,  for  want  of  a  knowledge 
of  the  relative  powers  of  men,  horfes,  and  other  firft  movers. — Obfervation  refpefting  the 
beneficial  tendency  of  improvements  in  the  application  of  thefe  fortes.  Power  of  wind- 
mills. Horizontal  mills.  Water-wheels  with  inclined  pallets.  Inftruftions  for  meafuring  the 
quantity  and  power  of  ftreams  of  water.  Explanation  of  the  manner  in  which  this  power  ope- 
rates. Example  in  detail  to  afcertain  the  force  of  a  flream  to  be  applied  to  an  underihot-wheel 
to  raife  w,iter,  to  grind  corn,  or  to  perform  the  work  of  a  certain  number  of  men  or  horfes.  En- 
quiries refpefting  the  medi\im  effe&  of  animal  power.  Overfhot-wheels.  Eafy  method  of  le- 
velling to  determine  the  fall  of  a  ftream  of  water. 

IX.  Enquiries  concerning  the  Invention  and  Praflice  of  the  Art  of  Hat- 
making.  —  —  —  —  —  p.  467 

X.  New  Obfervations  on  the  Method  of  producing  very  loud  Fulminatlons 
with  various  Bodies  by  Means  of  Phofphorus.     By  Citizen  Brugnatelli. 

p.  468 

Experiments  in  which  detonations  were  produced  by  placing  a  fmall  portion  of  phofphorus  ur  n 
various  fubftances  containing  oxygen,  and  ftriking  tHera  with  a  hammer.  Thtfe  were  nitr.  re 
of  filver,  oxygenated  muriate  of  potalh,  the  nitrates  of  bifmuth  and  of  mercury,  common  nitre, 
the  fulphates  (which  did  not  fu  ceed)  and  certain  metallic  oxydes.  Experiments  in  which  fnl- 
phur  and  charcoal  were  ufed  inftead  of  phofphorus.    Additions  and  remarks  by  Van  Mons. 

Tunnel 


CONTENTS.  scxi 

Tunnel  beneath  the  Thames.  —  —  —  p.  473 

Abridged  account  of  the  plan  and  proceedings  relating  to  the  propofed  tunnel  beneath  the  Thames, 
at  Gravefend.— Lift  of  the  committee  of  fubfcribers,  with  other  particulars  relating  to  the  fub- 
fcription. 

On  Mr.  Cartwright's  Apparatus  for  rendering  the  piftons  of  Steam  Engines 
tight  by  Metallic  Fittings.  —  —  —  P«  47^ 


February    1799. 

Engravings  of  the  following  Obje£l:s:  i.  A  New  Air-pump.     2.  A  remarkable 
Lunar  Halo  :  and,  3.  Figures  illuftrating  the  lateral  Motions  of  Fluids. 

r.  On  the  Corundum  Stone  from  Afia.  By  the  Right  Hon.  Charles  Gre- 
ville,  F.R.S.  _  _  _  p.  477 

Early  notices  of  the  corundum  ftone.     Particular  account,  and  topographical  remarks  on  the  place 
where  it  is  ifound  in  India.    It  is  in  common  ufe  in  China.    Obfervations  refpeAing  its  general 
\    properties,  fpecific  gravity,  &c. 

II.  An  Account  of  a  Angular  Flalo  of  the  Moon.  In  a  Letter  from  William 
Hall,  Efq.  of  Whitehall,  to  Sir  James  Hall,  Bart.  F.R.S.  Edin.  p.  485 

Lunar  Halo,  confifting  of  a  circle  round  the  moon  of  about  la"  in  diameter,  with  another  palling 
through  the  moon  of  about  i  la*,  and  very  much  inclined  to  the  horizon. 

III.  Experimental  Refearches  concerning  the  Principle  of  the  lateral  Communica- 
tion of  Motion  in  Fluids,  applied  to  the  Explanation  of  various  hydraulic  Phe- 
nomena. By  Citizen  J.  B.  Venturi,  Profeffor  of  Experimental  Philofophy  at 
Modena,  Member  of  the  Italian  Society,  of  the  Inftitute  of  Bologna,  the  Agra- 
rian Society  of  Turin,  &c.  —  —  —  P' 487 

A  fudden  bend,  or  right  angle,  in  a  pipe,  deftroys  nearly  half  the  velocity  of  a  fluid  moving  through 
it.  Enlargements  are  fcarcely  lefs  noxious.  Explanation  of  the  efFefts  of  the  water-blowing 
machine.  ■  Curious  method  of  draining  land  by  a  fall  of  water  without  machines,  Caufes  and 
effefts  of  the  eddies  and  whirls  in  rivers. 

IV.  Concerning  a  new  Variety  of  Argillaceous  Iron-ore.  By  Samuel  L.  Mit- 
qhill,  M.D.  uf  New  York.  —  —  —  p.  494 

Argillaceous  iron-ore  figured  like  bafaltes.  Argument  deduced  in  favour  of  the  aqueous  origin  of 
bafaltes. 

V.  Concerning  the  Invention  of  the  Eleftricai  Doubler.  By  Mr.  John 
Read.  —  '         — ,  —  P«  495 

Explanatory  letter,  with  remarks  on  its  contents. 

VI.  Inquiries  refpefting  the  Conftrudion  of  a  Water-wheel,  and  the  Manufadure 
of  Bricks.    By  a  Correfpondent.         — .  —  P-  497 

VII.  On 


XXlt 


CONTENTS. 


VII.  On  the  Combuftion  of  Phofphorus.  —  —  P«  49? 

VIII.  Pyrometrical  EfTays  to  determine  the  Point  to  which  Charcoal  is  a  Non-con- 
duftor  of  Heat.     By  Citizen  Guyton.  —  —  p.  499 

Comparative  experiments  with  Wedgwood's  pyrometer  pieces,  one  of  which  was  furrounded  with  . 
charcoal,  and  the  other  with  fand.    The  former  piece  was  much  lefs  affefted  by  the  heat  than  the 
latter. 

IX.  Defcription  of  an  Air-pump  of  a  new  ConftrucElion.     By  the  Rev.  James 
Little,  of  Lacken,  in  the  County  of  Mayo,  in  Ireland.  —  p.  ^or 

New  Air-pump,  with  an  horizontal  barrel,  folid  pifton,  and  (lop-cock,  between  the  barrel  and  the 
receiver. 

X.  Obfervations  on  Chemiftry  and  Natural  Hiftory.  By  Profeflbr  Van- 
delli.  —  —  —  —  p.  508 

Accounts  of  foffil  Pruffian  blue  at  Minas  Geraes,  in  Brazil,  and  alfo  of  a  very  large  mafs  of  native 
copper. 

XI.  On  the  Manufafture  of  Hats,  and  other  ObjeSs.    By  a  Correfpondent. 

P-  509 

XII.  Extraft  of  a  Letter  from  Citizen  Ramond,  Aflbciate  of  the  National  In- 
ftitute  of  France,  &c.  to  Profeflbr  Haiiy,  Member  of  the  Inftitute  at  Paris, 
refpefting  two  Excurlions  to  Mount  Perdu,  the  moft  elevated  Summit  of  the 
Pyrenean  Mountains.  —  —  ■ —  p-  510 

Various  obfervations,  the  moft  remarkable  charafter  of  which  is  that  the  moft  elevated  fummit  of 
the  Pyrenean  mountains  is  calcareous,  and  abounds  with  the  remains  of  marine  animals. 

XIII.  An  Abftraft  of  a  Memoir  on  the  Foffil  Bones  of  Animals.  By  Citizen 
Cuvier.  ' —  —  —  —  P-  5 1 2 

Enumeration  of  extinft  fpecies  of  animals,  of  which  the  bones  have  been  found.  Siberian  mam- 
mouth.    Animal  of  the  Ohio.     Animal  whofe  teeth  form  turquois  ftone.     Rhinoceros.     Giant 

floth  of  the  royal  cabinet  at  Madrid.     Animal,  or  bear,  of  Bayreuth.    of  Montmartre  ; 

of  Verona.     Stag  of  Ireland,  &c.     Beeves,  &c.     General  Reflections. 

XIV.  Extradt  of  a  Memoir  of  Prouft,  entitled  Enquiries  concerning  Tin. 
By  Citizen  Darcet.  —  —  —  P*  5^5 

Tin  fubjefled  to  the  aftion  of  ftrong  nitric  acid,  or  with  the  afliftance  of  heat,  acquires  40  parts  of 
oxygen,  and  is  infoluble  ;  but  with  weak  cold  nitric  acid  it  acquires  only  30  parts.  ExperimenU 
and  obfervations  refpefting  the  tranfitions  of  oxygen. 

XV.  Scientific  News,  &c.    .  p.  518 

Conftruaion  of  lantern  pinions  of  glafs  for  mill-work.  Conftitution  of  the  Ligurisn  Inftitute.  In- 
ftitute of  Cairo  in  Egypt. 

XVI. 


CONTENTS. 


xxtii 


XVI.  Obfervations  on  the  Differences  which  exift  between  the  Acetous  and 
Acetic  Acids.    By  J.  A.  Chaptal.  —        ^    —  —  P-  518 

The  acetous  and  acetic  acids  are  not  the  fame  when  equally  diluted.   The  acetous  acid  contains  a  larger 
proportion  of  carbon. 

Accounts  of  Books,  &c.  —  —  —  p.  5^3 

Rollo  on  diabetes  mellltus.    Condorcet's  method  of  accounts.    On  Mr.  Lowi-y's  ruling  machine. 


MARCH     1799. 

Engravings  of  the  following  Objefts :  A  new  univerfal  Ele£lrometer,  by  Mr. 
Cuthbertfon ;  and,  2.  Configurations  of  the  Cryftals  of  Corundum  Stone  from 
Afia. 

I.  An  Account  of  Improvements  in  eleflrical  Batteries^  a  Method  of  augment- 
ing their  Power,  with  Experiments  ;  (hewing  the  proportional  Lengths  of  Wire 
fufed  by  different  Quantities  of  Eleftricity,  and  a  Defcription  of  a  new  univerfal 
Eleftrometer.  By  Mr.  John  Cuthbertfon,  No.  53,  Poland-ftrcet,  London, 
1799.  _  _  —  _  __  p-s^s 

Account  of  the  power  of  batteries.  Mr.  Brooke's  method  of  increafing  the  power  of  eleftrical  jars. 
Difcovery  of  a  method  of  producing  this  efFeft,  by  rendering  them  damp,  Defcription  of  a  new 
eleftrometer,  which  (hews  the  degree  of  eleftrization,  the  repulfive  force  in  weight,  and  ope- 
rates of  itfelf  as  a  difcharger.  Courfe  of  Experiments  on  the  explofion  of  wind,  by  jars,  in  the 
dry,  and  in  the  damp  ftates.     Inquiry  refpefting  the  caufe  of  this  efFeft. 

II.  Difcovery  of  Sulphate  of  Strontan,  near  Sodbury,  in  Gloucefterfhire,  by  G,  S. 
Gibbs,  B.M.   F.R.S.  _        ,        _  _  p.^^s 

III.  On  the  Corundum  Stone  from  Afia.  By  the  Right  Honourable  Charles 
Greville,  F.R.S.  —  —  —  p.  536 

Great  probability  that  corundum  maybe  found  in  Europe.  Obfervations  on  the  Hiftory  and  great 
utility  of  Cryftallograpfey,  An  analytical  defcription  of  the  cryftalline  forms  of  corundum,  by 
the  Count  De  Bournon.  >- 

IV.  On  Water- wheels.  —  ^^  —  p,  544 

Obfervations  on  the  power  of  different  Water-wheels, 

V.  On  the  Glafs  Trundles  of  Citizen  Renaut;  and  the  Duration  of  the  Teeth 
ofMill-work.     By  C.  B.  —  —  —  p- 546 

VI.  On  Dr.  Parr's  Theory  of  Light  and  Heat.    By  a  Correfpondent      p.  ^47 
Scientific  News,  and  Accounts  of  Books  —  — ■  p.  548 

Inftitute  of  Cairo.  An  Account  of  the  Operations  carried  on  for  accomplifliing  a  Trigonometrical 
furvey  of  England  and  Wales,  from  the  commencement  in  1784,  to  the  end  of  the  year  1796. 
Public  Inflitution  for  diffufing  knowledge  and  facilitating  the  general  introduftion  of  ufeful  me- 
'Cfcanical  improvements. 


JOURNAL 


OP 

NATURAL   PHILOSOPHY,   CHEMISTRY, 

AND 

THE   ARTS. 


APRIL     1798. 


ARTICLE    I. 

A  Memoir  and  new  Experiments  on  the  Artificial  Cinnabar  of  Mr.  Kirchoff.  By  the  Count 
JpQLLOS  D£  MOVSSIN  POUSCHIN,  Chamberlain  to  his  Majejly  the  Emperor  of  all  the 
RuJJias,  Vice-Preftdent  of  the  College  of  Mines ^  Honorary  Member  of  the  Imperial  Academy 
of  Sciences,  at  Peterjhurg*,  isfc.  is'c. 

J.  H  E  annual  confumption  of  cinnabar  by  z  variety  of  manufa£lurcrs  and  artifts,  and 
the  certain  falc  of  this  beautiful  colour,  render  it  undoubtedly  an  interefting  object  of 
political  economy  for  all  Hates  which  poflefs  the  ores  of  quickfilver,  as  well  as  a  branch 
of  fpeculation  for  the  merchant  which  has  hitherto  fupported  the  manufa£tories  of  ver 
milion,  and  has  even  fixed  the  attention  of  the  induftrious  Hollanders,  who  not  being  able 
to  derive  advantage  from  the  fabrication  of  this  produ£t  at  firft  hand,  have  eftabliflied,  as 
it  is  faid,  mills  for  cinnabar,  in  which  this  colour  gains  the  brilliancy  and  fmoothnefs  ne- 
ceflary  for  its  employ  in  the  arts.  This  procefs,  which  they  myftcrioufly  conceal,  has 
hitherto  been  attended  with  profits  the  more  confiderable,  as  it  is  pretended  that  great 
part  of  the  cinnabar  which  is  adulterated  by  different  procefles  is  vended  through  Europe 
from  thefe  manufaftories  at  firft  handf.     The  methods  by  which   cinnabar  has  hitherto 

been 

'  Tranflated  from  the  French  manufcriptj  communicated  by  Charles  Hatchett,  Efq.  who  received  it  from 
the  author,  with  fome  fpecimens  of  the  cinnabar,  which  he  finds  to  be  of  the  beft  quality.  The  memoir  was 
BddrelTcdto  the  Socicte  des  Amis  Scrutateiirs  dc  la  Nature. 

t  Mr  Tuckert,  who  feveral  times  affiftcd,  or  was  prelcnt  during  the  preparation  of  artificial  cinnabar  at 
the  manufaftory  of  Mr.  Brand,  wirliout  the  Utrccht^r-.te  at  AmfterJam,  has  given  an  account  of  the  procefles 

Vol,.  II.— ArBiL  1798.  B  in 


2  Ordinary  Procefs  for  mahng  Cinnahar  by  Sullimation. 

'beeH.'bfetain?3'5r'e  too  \ven*'knbwn,antf  It  would  te  fuperfluous  to  mention  them  liere. 
But  as  the  various  inconveniences  of  fublimation,  grinding,  and  the  other  preparations  of 
this  colour,  are  frequently  prejudicial  to  the  health,  and  fonietimes  expofe  the  lives  of  the 
■workmen  to  inevitable  danger;  and  as  the  lofs  of  veflels  and  the  expence  of  fuel  are  but  too 
frequently  fek  by  thofewho  nndertake  this  fabrication  ;  it  is  evident  that  a  method  of  ob- 
taining cinnabar  fubjedl  to  none  of  thefe  inconveniences,  and  requiring  little  of  expencc 
excepting  the  firlt  cod:  of  the  mercury,  rauft  become  truly  valuable  to  this  branch  of  in- 
duftry.  We'  are  indebted  to  Mr.  KirchofF,  a  young  chemift  of  the  greateft  hopes,  who  is 
attached  to  the  pharmaceutic  department,  for  the  firft  difcovery  of  a  method  no  lefs  in- 
geHicus  than  obvioufly  of  gxeat  probable  advantage  to  commerce.  His  claim  in  thisTefpe£t 
is  beyond  controverfy.  For,  though  cinnabar  has  been  obtained  in  the  humid  way  by 
means  of  volatile  liver  of  fulphur,  there  never  could  have  been  any  hope  of  applying  that 
method  to  the  purpofeg  of  trade,  on  account  of  the  heavy  expence  of  the  re-agent.  But 
the  intermedium  ufed  by  Mr.  KirchofF  promifes,  on  the  contrary,  all  the  advantages 
which  the  mod  fcrupulous  calculation  can  require,  and,  when  brought  to  pexfe£tion,  will 
probably  caufe  the  method  of  fublimatlon  to  be' abandoned  by  all  who  may  be  defirous 
of  engaging  in  this  branch  of  commerce,  without  expofing  themfelves  to  unncceffary 
rifque. 

I  (hall  proceed  to  lay  before  this  illuftrious  Society  all  the  details  of  the  procefs  of 
Mr.  KirchofF,  as, well  as  the  inconveniences  which  have  hitherto  prefented  themfelves. 
It  is  with  great  pleafure  that  I  avail  myfelf  of  this  opportunity  of  doing  juflice  to  the 
merits  of  this  chemift, which  have  been  hitherto  concealed  by  his  excefs  of  modefty ;  and  I 
have  annexed  to  this  memoir  my  own  proper  experiments,  which  have  enabled  me  to  re- 
move feme  of  the   principal  difficulties  which  KirchofF  met  with  in  his  work.     I  have  no 

in  Crell's  Journal,  of  which  an  abftraft  is  inferred  in  the  fourth  volume  of  the  Annales  de  Chimie,  page  jj. 
It  is  concifely  as  follows  :  (i.)  Ethiops  mineral  is  prepared  by  combining  150  pounds  of  fulphur  with  loSo 
.pounds  of  pure  mercury,  by  a  moderate  heat,  in  a  fiat-bottomed  polilhed  iron  vtflel.  2.  The  ethiops,  after 
flight  pulverization,  is  put  into  earthen  bottlas,  each  capable  of  containing  a  quart  of  water.  3.  Three  large  pots 
©r  fublimatory  veffcls,  made  of  very  pure  clay  and  fand  and  luted,  are  then  taken  and  placed  upon  iron  circles 
over  furnaces,  conftrufted  in  fuch  a  manner  that  tlie  flame  of  the  fuel,  which  is  turf,  circulates  freely  round 
the  veffels  to  two-thirdsof  their  height.  4.  When  the  veflels  are  red-hot,  a  bottle  of  the  ethiops  is  poured. into 
the  hrft,  another  into  the  fecond,  and  another  into  the  tbitd.  In  theTubfcqucnt  progrefs  of  the  operation,  two, 
three,  and  perhaps  more  bottles  may  be  poured  in  at  a  time  ;  but  this  depends  on  the  ftrength  of  the  inflam- 
ination  exhibited  by  the  ethiops  after  its  introduftion,  the  flame  of  which  fometimes  rifes  to  the  height  of 
four  and  even  fix  feet.  When  this  is  a  little  diminiflicd,  the  mouth  of  the  veffel  is  covered  with  a  plate  of 
iron,  one  foot  fquare  and  an  inch  and  a  half  thick,  which  perfeftly  clofes  it.  In  this  manner  during  thirty- 
four  hodrs  the  whole  of  the  prepared  matter  is  introduced  into  the  three  pots ;  that  is  to  fay,  into  each  pot  360 
pounds  of  mercury  and  50  of  fulphur.  5.  The  fire  is  then  kept  up  till  the  fublimation  is  completed,  and  after- 
wards fuflfered  to  go  out ;  which  requires  36  hours  from  the  time  of  the  complete  charge.  It  is  judged  to  have 
the  proper  intenfity,  when,  upon  taking  off  the  cover,  a  brifk  flame  appears,  but  does  not  rife  more  than  three 
or  four  inches  out  of  the  pot.  6.  During  the  hft  36  hours,  the  mafs  is  ftirred  ^very  quarter  or  half  hour 
with  an  iron  rod.  7.  When  all  is  cold,  the  veffcls  are  removed  by  means  of  the  iron  circles,  which  prevent 
their  breaking.  The  cinnabar  is  taken  out  by  breaking  the  veffel.  Each  pot  conftantly  affords  4,00  pounds  of 
cinnabar,  the  lofs  of  original  weight  in  each  being  10  pounds.  The  cinnabar  does  not  attach  itfelf  to  the 
plates  of  iron,  becaufe  they  are  continually  taken  off  excepting  towards  the  end,  when  the  velTels  are  left  un- 
touched.   Thefe  plates  are  not  in  the  leafl  corroded.     N. 

Other 


New  Procefs  In  the  Humid  H^ay.  3    * 

■other  claim  than  that  of  having  endeavoured  to  render  his  difcovcry.  as;  ufeful-srs  poflible  i«i'i 
technical  chemilts.  >  ' 

Mr.  KirchofF,  who  has  operated  in  the  fmall  Way  only,  gives  the  following  proportions  for': 
the  produ£lion  of  cinnabar  in  the  humid  way: 

Three  hundred  grains  of' mercury   are  triturated  in  a  velTfl  or  cup  of  porcelain,   with    , 
68  grains  of  flowers  of  fulpliur,. until  an  ethiops  is  accurately  produced,  in  which  no  meti  ' 
taUio  glob»les;can  be  perceived  by  the  magnifier.     As  this  degree  of  union  of'  the  nief-  ' 
cury  and  fulphur  cannot  be  obtained  when  both  are  perfeftly  dry,  Mr.  KirchofF  adds  »^ 
few  drops  of  a  folution  of  cauftic  vegetable  alkali ;  and  when  the  union  of  the  mercury  antf  ' 
;fulphur  is  complete,  he  adds  to  the   mixture   a    foliitipn  of  160  grains  of  the  fame  alkali 
diflblvedin  an  equal  quantity  of  water.     He  heats  the  vefl'el  containing  thefe  ingredients 
over  the  flame  of  a  candle,  and  triturates  without  interruption  during  the  heating  with  a' 
gla.fs  pellle.     In  proportion   as  the  liquid  evaporates,  he  adds  clear  water  from  time  tdo 
time,  fo  that  the  ethiops  may  be  eonftantly  covered  to  the  depth  of  near  an  inch.    For  the 
above  quantities,  it  is  requifite   to  continue  the    trituration  nearly  two  hours ;  at  the  endo 
■of  which  time  the  mixture  begins   to  change  from  its  original  black  colour    to    a  brown,  ' 
■which  ufually  happens  when  a  large  part  of  the  fluid  is  evaporated.     From  this  firfl  mo- 
ment the  tranfition  from  brown  to  red  is  very  rapid.     No  more  water  is  then  to  be  added, 
but  the  trituration  muft  be  continued  without  intermiflion.     When  the  mafs  has  acquired 
the  x:onriftence  of  a  jelly,  the  red  colour  becomes  more  and  more  bright  with  an  incredible 
degree  of  quicknefs.     This  is  the  moft  important  point  of  time  for  the  fuccefs  of  the  ope- 
ration.    For,  if  the  heat  be  not  continued  long  enough,  the  colour  will  not  acquire  the  ut- 
moft  degree  of  beauty  ;  and  on  the  contrary,  if  it  be  continued  only  two  feconds  too  long, 
the  fine  red  of  the  cinnabar  pafles  as  quick  as  lightning  to  a  dirty  brown.     Mr.  KirchofF, 
as  well  as  Mr.  Lowitz,  who  has  repeated  his  experiments,  could  not  fucceed  in  amending 
this  brown  colour  ;  which  confequently  renders  the  fuccefs  of  the  operation  very  precari- 
ous.    This  inconvenience  is  produdlive  of  another  ;  namely,  that  it  is  nearly  impolTible,  at 
the  inftant  of  the  produftion  of  the  colour  of  the  cinnabar,  to  make  any  obfervation  of  the 
quality  of  the  tint.     For  the  colour  of  the  liver  of  fulphur  mafks  that  of  the   cinnabar ; 
fo  that   in   fome   inftances  the    moft  beautiful  red  is   obtained,  and  in  others    a   colour 
inclining   to  orange,  which,  though  bright  and  vivid,   is  not  the  tinge   required  in    this 
produfl.     In  one    of  his  experiments,  Mr.  KirchofF  obtained  a  cinnabar  which  abfoluteljs* 
pofTeflTed  the  colour  of  carmine ;   but  he  had  this  good  fortune   only  once,  when   he  had" 
no  expectation  of  fo  beautiful  a  product,  and   did  not   therefore  note  the  attendant   cir- 
cumftances. 

This  is  nearly  the  whole  detail  of  the  experiments  hitherto  made  by  Meflrs.  KirchofF 
and  Lowitz.  The  cinnabar  they  obtained  ftill  exhibited  mercury  in  the  metallic  (late, 
which  it  was  rather  difHcult  to  get  rid  of,  and  did  not  appear  until  after  the  filtration  of 
the  liver  of  fulphur,  and  the  edulcoration  and  drying  of  the  vermilion. 

I  fhall  now  proceed  to  relate  what  I  have  done  refpedling  this  objedt,  principally  with  a 
view  to  facilitate  the  manufa£turing  in  the  large  way,  the  reftoration  of  the  cinnabar  which 
had  afFumed  a  brown  colour  inftead  of  red,  and  the  certainty  of  the  tint  in  mafFcs  fome- 
what  confiderable.  I  am  very  far  from  being  content  with  the  fuccefs  of  my  experiments ; 
but  I  think  I  have  at  leaft  difcovcred  great  part  of  the  theory  of  the  operation,  and  that  in 

B  2  pradlice 


4  New  Frocefsfor  mahin^  Attific'tal  Clnnnhar  In 

praftice  the  manufadurer  will  foon  difcover  the  neceflary  proportions  and  manipulationsr 
I  therefore  claim  and  hope  for  the  grant  of  indulgence  in  favour  of  the  defire  I  have,  that 
the  valuable  difcovery  of  KirchofF  may  fpeedily  become  as  ufeful  to  fociety  as  undoubtedly 
it  will  fooner  or  later  be. 

The  firft  experiment  I  made  in  fmall,  according  to  the  exa£l  proportions  of  KirchofF, 
^id  not  fucceed.  I  could  not  transform  my  ethiops  into  cinnabar.  I  attribute  this  want 
of  fuccefs  to  an  evaporation  too  rapid,  and  the  want  of  a  fuflicient  quantity  of  fluid  ;  not 
having  added  water  in  proportion  as  the  mixture  became  thick,  fo  that  the  whole  foon  be- 
came perfe£lly  dry.  The  mafs  became  ftrongly  attached  to  the  china  cup,  and  con- 
ftantly  preferved  its  black  colour.  I  recommenced  the  operation  with  more  fuccefs,  and 
all  my  experiments  afforded  cinnabar  more  or  lefs  beautiful,  provided  the  mixture  at  the 
commencement  was  kept  at  the  proper  degree  of  fluidity.  Moft  frequently  however  I 
obtained  a  colour,  which,  though  very  brilliant,  inclined  rather  to  yellow  than  red;  a  fault 
which  the  cinnabar  of  fublimation  poffeffes  but  too  frequently,  and  is  fometimes  a  proof 
of  its  falfification.  Among  the  colours  which  I  obtained,  brown  prefented  itfelfbuttoo 
frequently,  in  confequence  of  having  negledled  the  moment  of  terminating  the  operation. 
I  made  the  following  experiments  on  thefe  defeftivc  colours  : 

After  well  edulcorating  a  cinnabar  of  this  kind,  I  poured  on  three  different  portions  :  the 
nitrous,  the  acetous,  and  the  muriatic  acids.  Thefe  were  expofed  for  feveral  hours  to  a 
mild  digefling  heat.  I  had  fuppofed  that  the  defeft  of  the  colour  might  arife  either  from 
a  partial  redu£lion  of  the  mercury,  or  partial  fufion  of  the  fulphur,  or  perhaps  from  an 
adulteration  of  the  mercury  by  lead.  In  thefe  three  experiments,  therefore, my  aim  was  to 
diffolve  the  reduced  mercury, to  oxide  the  fulphur,  or  to  carry  off  the  lead  by  the  acetic  acid. 
None  of  thefe  experiments  ahfwered  my  expectation ;  for,  though  part  of  the  mercury 
was  diffolved  and  part  of  the  fulphur  oxided,  the  colour  continued  brown.  That  with  the 
nitrous  acid  was  even  darker.     The  acetic  acid  afforded  no  indications  of  lead. 

As  the  refult  of  thefe  experiments  Ihowed  that  the  bad  colour  of  the  cinnabar  did  not 
arife  from  a  portion  of  reduced  mercury,  I  wilhed  to  know  whether  the  metal  were  not 
combined  with  too  large  a  portion  of  fulphur;  for  which  purpofe,  I  digefted  cauftic  al- 
kali on  the  cinnabar.  The  alkaline  folution  became  yellowifli,  and  the  colour  of  the  cin- 
nabar fomewhat  lighter,  but  was  not  a  good  red.  It  always  inclined  to  yellow  ;  and  though 
it  approached  very  near  the  colour  of  common  cinnabar,  and  was  even  more  vivid,  yet  it 
was  not  red  enough. 

I  had  little  cxpeftation  of  reftoring  the  proper  colour  and  vividnefs  to  my  damaged  cin- 
nabar. Nothing  more  remained  but  to  try  the  addition  of  mercury  to  the  brown  colour 
which  was  the  objeft  of  my  refearch.  I  therefore  moiftened  near  an  ounce  and  a  half  of 
this  colour  with  water,  then  gradually  added  near  three  ounces  of  running  mercury,  and 
triturated  the  whole  on  a  very  hard  Siberian  porphyry.  Contrary  to  my  expe6lation,  the 
mafs,  inflead  of  becoming  black,  affumed  the  colour  of  an  extremely  pale  cinnabar,  with- 
out the  fmalleft  degree  of  fire  or  livelinefs.  I  then  mixed  two  drams  of  the  flowers  of 
fulphur,  and  colle£ted  the  whole  in  a  porcelaine  cup.  Upon  this  I  poured  a  folution  of  the 
cauftic  alkali,  evaporated  as  before  to  a  very  thick  confiftence.  The  mixture  paffed  from 
yellow  to  an  obfcure  brown,  and  at  the  moment  of  the  thickening  a  large  quantity  of 
running  mercury  was  feen  at  the  bottom  of  the  cup.    I  added  a  dram  and  a  half  of 

fulphur. 


the  Humid  Way- — General  InJlruBkns,  5 

futphur,  with  a  few  drops  of  water,  and  triturated  the  whole  until  the  mercury  had  entirely 
combined  with  the  reft  of  the  mixture.  I  then  added  water,  and  began  the  evaporation, 
agitating  the  mixture  continually  with  the  peftle.  The  brown  colour  began  towards  the 
end  of  the  evaporation  to  brighten,  and  at  laft  changed  to  the  colour  of  bad  fealing-wax, 
conftantly  inclining  to  brown.  Forefeeing  that  if  I  continued  the  evaporation  I  fliould 
rifk  a  fecoud  obfcuration  of  the  colour,  I  placed  the  cup  which  contained  the  mixture  on 
a  ftove  which  had  been  heated.  At  that  time  I  totally  defpaired  of  correfting  the 
colour  of  cinnabar  fpoiled  at  ths  firft  evaporation ;  but  having  infpe£ted  my  cinnabar  at 
the  end  of  two  hours,  I  faw  with  pleafure  that  the  colour  had  become  finer  as  the  mafs  be- 
came thicker.  I  triturated  it  in  the  cup  with  the  addition  of  a  few  drops  of  water,  and 
repeated  this  operation  five  or  fix  times  in  the  courfe  of  the  day.  At  the  end  of  24  hoUrs, 
my  cinnabar  was  very  thick  and  very  good. ,  I  added  mote  water,  and  left  the  colour  on 
the  ftove  for  three  days  ;  at  the  end  of  which  the  cinnabar  had  acquired  the  utmoft  bril- 
liancy, and  was  equal  to  the  fineft  fpecimens  of  Mr.  KirchofF,  excepting  that  in  which  he 
had  obtained  a  fliade  of  carmine,  as  I  have  already  remarked.  After  repeating  this  experi- 
ment with  fuccefs  with  one  pound  of  mercury,  thirty-five  drams  of  flowers  of  fulphur,  and 
ten  ounces  of  cauftic  alkali,  I  found  reafon  to  make  the  following  general  obfervations  upon 
this  procefs  : 

It  is  neceflary  for  the  production  of  cinnabar, 

1.  That  the  mercury  fliould  be  perfe£lly  mixed  with  the  flowers  of  fulphur  ;  for  which 
reafon,  after  having  triturated  it  with  the  peftle  in  a  glafs  mortar,  with  the  addition  of  a 
fmall  quantity  of  cauftic  alkali  to  moiften  it,  it  muft  be  levigated  upon  porphyry,  or  fuch 
Other  hard  ftone  as  cannot  mix  its  particles  with  thofe  of  the  cinnabar,  becaufe  every 
foreign  fubftance  is  highly  prejudicial  to  the  beauty  of  the  colour.  If  the  quantities  ope- 
rated upon  exceed  one  pound,  it  will  be  neceflary  to  procure  a  mill  for  grinding  colours 
which  muft  alfo  be  of  a  filiceous  ftone.  The  mixture  upon  a  levigating  ftone  is  evidently 
tec  expenfive  for  a  manufafluring  procefs  in  the  large  way. 

2.  The  beft  vefl"els  for  evaporating  the  mixture  are  thofe  of  porcelaine,  or  the  yellow 
■ware  of  England.     The  peftles  ought  to  be  glafs. 

3.  The  heat  of  a  fand-bath  is  fufficient  to  this  operation.  The  heat  of  ebullition  is  not 
neceflary  •,  but  at  the  beginning,  particularly  when  there  is  much  liquid,  the  heat  muft  ap- 
proach as  nearly  as  poflible  to  that  of  boihng. 

4.  The  receptacle  in  which  the  fand  is  placed  muft  be  deep  enough  to  admit  the  whole 
of  the  porcelaine  or  earthen  veflel  in  which  the  cinnabar  is  produced,  to  be  plunged  there- 
i»,  and  environed  by  an  equal  atmofphere  of  heat.  The  fand  round  the  vefll-l  need  not 
exceed  the  thicknefs  of  a  full  inch. 

5.  The  mixture  muft  be  perpetually  ftirred :  otherwife  the  mafs  will  fubfide  by  its  weight, 
and  become  clotted  -,    a  circumftance  which  it  is  eflential  to  avoid. 

6.  A  certain  degree  of  thicknefs  is  requifite  during  the  operation,  in  order  to  afll)rd  a 
good  colour  •,  but  great  care  muft  be  taken  not    to  fufl^er  the  mafs   to  become  too  thick 
and  more  particularly  the    agitation   muft  be  ftrongly  kept  up  at  thefe  periods  of  con* 
denfation. 

7.  Though  it  is  poflible  to  obtain  from  the  fand-bath  a  very  beautiful  cinnabar  which 
may  be  immediately  edulcorated,  yet  it  is  much  more  prudent  and  advantageous  not  to 

fuiTcj- 


g",  Nuiv  Process  for  making  Cinnahar  in  the  Humid  Way. 

fufFer  tire  produft  to  acquire  its  whole  perfeftion  on  the  evaporating  furnace,  but  to  take 
it  in  time  from  the  fand-bath,  and  leave  it  for  three  or  four  days  in  a  degree  of  heat  equal 
to  that  of  the  (love  of  an  apartment  after  it  has  been  heated  for  two  or  three  hours.  Caic 
muft  be  taken  to  add  a  few  drops  of  water,  and  to  agitate  the  mixture  from  time  to  time. 
By  this  precaution,  the  difagreeable  event  of  feeing  the  colour  pafs  from  red  to  yellow,  and 
often  to  brown,  is  avoided,  as  well  as  the  fubfequent  labour  and  expence  of  trituration  with 
mercury,  and  additional  liver  of  fulphur. 

8.  Before  the  cinnabar  is  edulcorated,  it  maybe  left  to  become  almoft  perfedly  dry  by 
the  heat  of  the  ftove  -,  by  which  means  the  colour  will  acquire  the  mofl.  brilliant  tint. 

After  this  account  of  the  produ£lion  of  cinnabar  in  the  humid  way,  I  fhall  fpeak  of  the 
'edulcoration  and  drying  of  this  colour,  which  have  prefented  phenomena  of  the  grcateft 
importrcice  to  the  fabrication  iti  the  large  way,  and  are  alone  fufficient  to  fecurc  real  ad- 
vantages to  the  fpeculator  in  this  article. 

Ha,ving  obtained  ten  ounces  of  cinnabar,  I  poured  twenty  pounds  of  boiling  water  upon 
it  ill  a  large  eartlien  jar,  for  the  purpofe  of  difengaging  the  liver  of  fulphur.  At  that  mo- 
ment the  liquid  Was  obfcured  and  became  abfolutely  black.  I  {lightly  agitated  the  mixture. 
The  cinnabar  very  fpeedily  fell  to  the  bottom,  and  permitted  me  to  decant  this  black  li- 
quor, of  which  I  fhall  hereafter  fpeak.  After  having  poured  other  water  upon  the  cinna- 
bar, which  was  confiderably  beautiful,  it  acquired  a  flight  yellow  colour.  After  the 
fettling  of  the  colour,  I  decanted  it,  and  continued  to  edulcorate  until  the  decanted  water 
had  neither  the  faline  fulphureous  tafle,  nor  hepatic  fmell. 

When  I  had" poured  for  the  lad  time  five  or  fix  pounds  of  boiling  water  on  my  colour, 
I  agitated  it  ftrongly,  and  poured  it  out  into  a  veflel  of  cryftal  glafs.  A  plentiful  depofition 
of  colour  was  made  in  an  inflant.  It  was  not  bad,  but  did  not  poflefs  the  brilliancy  of  the 
particles  which  flpaced  in  the  water  above  this  depofition.  I  agitated  the  water  very 
flightly,  that  it  might  become  more  highly  charged  with  colouring  matter,  but  not  fo  much 
as  entirely  to  derange  the  mafs  which  had  fubfided.  I  rapidly  decanted  the  liquid  part  into 
another  veflel.  The  mofl;  denfe  portion  remained  at  the  bottom,  and  on  the  fides  of  the 
firfl:  glafs,  and  was  of  a  very  beautiful  colour.  I  repeated  this  wafli in g  four  times  with  the 
fame  precautions,  taking  care  always  to  pour  the  liquid  part  haftily  into  another  veflel. 
The  refidue  of  the  lafl;  waftiing  was  entirely  brown,  and  the  tints  of  my  cinnabar  were  beau- 
tiful in  the  fame  order  as  I  had  obferved  in  the  decantation.  That  is  to  fay,  the  colour  in  the 
firfl  vefltl  was  more  brilliant  and  lefs  deep  than  in  the  fecond,  and  fo  of  the  others.  This 
experiment  fhowed  not  only  that  wafliing  adds  to  the  beauty  of  the  cinnabar  obtained  by, 
the  procefs  of  KirchofF,  but  that  it  is  poflTible,  more  efpecially  in  works  on  a  large  fcale,  to 
obtain  a  great  variety  of  tints  by  mixture,  without  admitting  any  foreign  colour  or  ma- 
terial. 

After  having  thus  obtained  different  cinnabars  by  wafliing,  I  dried  them  on  a  furnace 
flightly  heated,  and  found  them  more  or  lefs  deep,  but  generally  very  good.  They  did  not, 
however,  poflefs  the  fire  of  fuch  cinnabars  as  inclined  to  a  yellow  colour.  I  put  thefe  co- 
lours into  capfules  of  paper,  and  left  them  for  fome  days  on  the  fame  flove,  which  had 
continued  to  be  regularly  heated.  At  the  end  of  this  time,  upon  opening  my  papers  it 
appeared  to  me  that  the  colour  was  improved;  and  had  in  particular  become  more  lively 

4  thaa' 


iVi?w  ProMfsfor  makitig  Cinnnhar  in  the  Humid  Way,  ,3j|  ■ 

than  on  the  firft  day.  In  order  to  afcertain  whether  this  phenomenon  was  owing  to  fimple 
drying,  or  to  heat,  I  placed  a  pinch  of  the  lighted  colour  on  a  fmall  piece  of  glafs,  which 
I  heated  very  flroBgly  with  a  candle.  ]  then  enjoyed  a  very  beautiful  fight,  of  which  the 
j:efult,gave  me  the  greateft  p!e?fure.  The  powder  of  cinnabar  became  brown  in. an  inftant, 
and  foon  afterwards  nearly  blaclc,  or  rather  of  the  deeped  violet  grey;  but  when,  on  the 
fuppofition  that  I  had  fpoiled  my  cinnabar,  I  threw  It  from  the  glafs  upon  a  paper,  I  was 
very  agreeably  furprifed  -to  obfc-rve  it  in  the  twinkling  of  an  eye  pafs  through  all  the  tranfi- 
tions  from  obfcure  violet -to  a  beautiful  carrtiine  red,  and  to  obferve  more  particularly  that 
this  colour  had  acquired  the  nrc  and  brilliancy  which  was  wanting  before  the  experiment. 
As  an  objcft  of  COmparifon,  I  had  fome  cinnabar  of  commerce,  of  which  the  pond,  or  forty 
pounds  (Ruffian),  is  fold  at  Petcrfburgh  for  eighty  roubles.  I  put  a  pinch  of  this  on  the  fame 
,ilip  of  glafs,  and  fvbjc^ed  it  to  .the  fame  treatment.  The  colour  fpeedily  became  black, 
arrd,  after  Cooling,  acquired  a  very  bad  deep  brown  tinge,  refembling  umber  of  a  bad  quality, 
without  recovering  its  original  red.  I  repeated  this  experiment  in  a  larger  way  with  the 
.fame  fuccefs,and  by  that  means  afcertained  a  method  of  giving  in  general  much  brilliancy 
to  my  cinnabar,  and  of  producing  the  mod  brilliant  carmine  tint.  This  heat,  which  muft 
be  very  drong,  requires,  neverthelefs,  to  be  condu£led  with  much  prudence.  The  cinna- 
bar mud  not  fume,  nor  exhibit  grey  globules  on  its  furface  ;  for  in  thefe  cafes  it  would  be 
eflc6lually  fpoiled.  This  phenomenon  feems  to  prove  a  decompofition  and  abforption  of 
air;  but  it  remains  to  be  fliown  whether  it  be  hydrogene,  oxygene,  or  azote,  which  the  cin- 
nabar takes  up  in  this  experiment. 

Thefe  conditute  the  mod  eflential  fafls  I  have  obferved  with  regard  to  the  production 
of  cinnabar  in  the  humid  way.  I  intend,  when  time  permits,  to  give  a  continuation  of  this 
memoir.  1  have  already  made  fome  new  experiments,  which,  though  they  may  not  yet 
promife  any  advantage  to  the  manufadurer  in  the  large  way,  may  be  ufeful  to  the  painter 
and  intereding  to  the  chemid. 

The  black  liquor  which  I  at  fird  decanted  from  my  cinnabar,  depofited  a  fmall  portion 
of  ethiops,  not  furcompofed.     I  mud  add  in  conclufion,  that  the  manufacturer  in  the  large 
way  mud  of  courfe  fubmit  his  colour  to  feveral  elutriations,  colleft  the  depofitions  in  feve- 
ral  vcffels,  and  afterwards  mix  his  colours  when  dried.     It  would  be  likewife  neceflary  for 
the  finer  forts,  to  provide  a  furnace,  in  which  either  the  carmine  colour  or  the  Fequifite  fire 
and  brilliancy  may  be  given.     A  furnace  of  this  kind  may  very,  eafily  be  contrived,  and  it, 
would  be  unnecedary  to  defcribe  its  condrudlion  in  this  place.     It  is  my  widi,  that  the  fo- 
clety  to  whom  1  have  the  honour  to  addrefs  the  prefeut  memoir  will  confider  it  as  a  proof 
of  my  refpe£l  and  gratitude.     By  admitting  me  into  the  number  of  its  members,  a  new 
proof  is  afforded  of  its  indulgence  to  the  weaked  efforts  in  favour  of   the  fciences  and  na- 
tural hidory.     The  excellent  difcovery  of  Mr.  Kirchoff  has  led  me  to  afcertain  fome  new 
fafts,  of  which  I  am  defirous  that  commerce  diould  have  the  advantage  ;  but  the  honour  of  ■ 
the  difcovery  belongs  to  him,  and  deferves  to  be  the  more  infifted  on,  as  his  modedy  is  no  : 
lefs  CDnfpicuous  than  his  knowledge. 


U.  On 


fi  Pretended  CompofitioH  of  Atoiic  Gas. 

II. 

"0«  the  Luminous  Appearance  faid  to  be  exhibited  by  Phofphorus  in  Azotic  Gas. 
By  Dr.  Alexander  Nicholas  ScHERES^  Counfelkr  of  the  Mines  to  his  Serene  Highnefs 


Ai 


the  Duke  of  Saxen  Weimar*. 


jr  the  time  when  the  principles  of  the  new  theory  were  newly  difcufled,  the  enquiries 
of  chcmifts  were  employed  upon  fome  of  its  chief  aflertions.  Befides  examining  the  expe- 
riments that  metallic  oxyds  do  emit  oxygen  gas  during  their  redu£lion,  attention  was  alfo 
paid  to  another,  by  which  it  was  obferved,  that  the  combuftion  of  bodies  in  oxygen 
gas  is  always  accompanied  by  a  total  abforption. 

Mr.  Goettling,  who  exerted  his  induftry  on  fuch  experiments,  made  ufe  of  the  apparatus 
he  employed  in  feveral  experiments  of  the  fame  nature.  He  accidentally  obferved,  that 
the  phofphorus  continues  to  (hlne  for  fome  time  in  the  azotic  gas,  which  remains  after  its 
•combuftion  in  atmofpheric  air.  What  he  principally  obferves  on  this  head  is,  that  phof- 
phorus fliines  very  ftrongly  in  azotic  gas,  even  more  fo  than  in  atmofpherical  air ;  that  it 
is  converted  into  phofphoric  acid  by  this  procefs  ;  and  that  the  azotic  gas  totally  difappears. 
Hence  he  was  led  to  infer,  that  azotic  gas  muft  contain  oxygen,  as  well  as  the  oxygen  gas 
itfelf  does. — But  if  fo,  what  is  the  difference  between  thefe  two  fpecies  of  gas  ?  This 
queftion  was  apparently  folved  by  another  experiment  he  made.  Phofphorus  does  not 
fliine  fo  well  in  oxygen  gas  at  a  low  temperature,  as  it  does  in  the  azotic  ;  and  when  phof- 
phorus gives  light  in  atmofpherical  air,  it  is  always  with  extrication  of  heat ;  whereas  the 
light  is  not  attended  with  heat  in  azotic  gas.  He  concludes.thereforc,  that  the  azotic  gas 
confifts  of  oxygen  combined  with  light,  in  the  fame  manner  as,  on  the  other  hand,  the 
oxygen  gas  confifts  of  that  principle  combined  with  caloric  ;  and  moreover  that  caloric  has 
a  ftronger  affinity  to  oxygen  than  light  has. — On  this  Mr.  Goettling  builds  an  entirely  new 
theory  of  chemiflry,  from  the  confideration  that  the  new  mixture  of  azotic  gas,  which  he 
pretends  to  hive  difcovered,  does  not  admit  of  the  hitherto  adopted  way  of  explaining  its 
influence. 

Mr.  Goettling  has  explained  thefe  fafts  at  large  In  his  Beytrag  zur  Berichtigung  der  anti- 
fhlogijlifchen  Chemie.  Weimar  1794.  This  work  was  univerfally  well  received,  and  fome 
were  inclined  to  give  it  full  credit  without  further  examination.  Mr.  Goettling  himfelf  has 
publicly  explained  his  new  theory,  and  adapted  the  whole  of  his  chemical  ledures  to  that 
fyftem.  A  few  philofophers  only  ventured  to  offer  their  doubts  concerning  it.  Among 
thefe  are  Dr.Eimbke;  Intdligenzhlat  der  allg.  Hit.  Zeit.  1794,  No.  92,  and  Yelin ;  Erlang. 
gel.  Zeit.  1794,  No.  8o.  The  former  obferved,  that  when  phofphorus  had  ceafed  to  fliine  in 
atmofpheric  air,  it  would  afford  no  more  light  in  the  remaining  azotic  gas.  The  fccond 
found,  that  phofphorus,  after  undergoing  a  very  long  continued  heat  in  atmofpherical  air, 
does  alfo  leave  behind  an  aeriform  refidue,  in  which  the  phofphorus  will  by  no  means 
fiiine  any  longer. 

At  this  time  I  had  commenced  a  public  courfe  of  ledures  on  Chemiftry.     I  therefore 
thought  myfelf  obliged  to  make  new  enquiries  for  the  purpofe  of  giving  an  impartial  ac- 

*  Received  from  the  Author. 

count 


Coiitroverfy  rtfyeBing  'PhfphQnis  in  Azotic  Gas,  ^ 

Count  of  this  new  dlfcovery  i  but  to  avoid  being  led  into  error  by  individual  obfervations, 
as  is  frequently  the  cafe  with  experiments,  I  joined  Dr.  Jaeger  from  Stuttgard,  who  was 
juft  then  Vifiting  me  on  a  journey.  We  made  a  great  number  of  experiments  together, 
which  we  endeavoured  to  diverfify  in  every  poffible  manner,  in  order  to  difcover  all  the 
concurrent  circumftances.  In  the  ye/ia  gel.  Zeit  1794,  No.  113,  we  publiilied  a  fliort 
account  of  one  of  the  chief  occurrences ;  but  the  full  defcription  of  the  refults  from  our  in- 
Veftig'atidnS  Tortie  time  aftct  was  given  in  the  following  book,  Uaer  das  Lfuchtcn  ties 
Phofphors  tm  aimofpherifchen  Stickgas.  Weimar  1795-  To  this  work  we  have  added  ano- 
ther trCatife  on' GoEttling's  theory  by  Dr.  PfafF. 

The  chief  aim  of  this  enquiry  was  to  (hew  by  decifive  experiments,  ivhether  phoffhovus 
does  really  gix>e  ligfjt  in  azotic  gas,  and  whether  it  be  totally  decompofed  by  it  ?  Neitlier  of  thefe 
two  we  could  find  by  any  procefs  of  operation.  We  made  comparative  experiments  ovet 
Vrater  and  over  quickfdver,  and  clearly  perceived  that  Mr.  Goettling,  having  clofed  hi^ 
veflels  merely  by.  water,  Could  not  avoid  a  fource  of  error.  VVc  fpafed  no  exertions- t» 
invefttgate  as  eia£tly  as  poITible  the  method  of  preparing  azotic  gas,  and  by  that  means 
difcovered  a  variety  of  interefling  circumftances.  We  always  found  that-  the  fumes  of 
phofphnreous  add,  rifing  by  a  momentary  combuftion  of  phofphorus  in  atinofpherical  air,  did 
fo  far  envelope  the  remaining  portion  of  oxygen,  that  tlic  luminous  appearance  ftom  the 
onion  of  this  with  another  part  of  the  phofphorus  could  not  be  again  produced  until  the 
water  had  abforbed  the  acid  fumes.  We  always  found  however  that  this  light  was  of 
iliort  duration,  accompanied  by  a  very  inconfiderablc  diminution  of  the  elaftic  fluid,  ariS 
that  it  was  altogether  impoffible  to  caufe  the  phofphorus  to  emit  any  more  light  in  the  re* 
maining  air.  On  this  account  we  had  ev.ery  reafon  to  confider  this  as  pure  azotic  gas, 
and  to  declare  thofe  experiments  of  Mr.  Goettling  incorreft,  from  which  the  combuftioa 
of  phofphorus  was  faid  to  take  place  in  the  pure  ft  azitic  gas. 

To  all  this  Mr.  Goettling  made  no  reply,  except  that  he  gave  an  anfwer  in  the  Intelli- 
genxbl.  der  allgem.  Literat.  Zeit.  1794,  No.  117,  to  our  firft  very  (liort  notice,  tending  to 
place  the  whole  inveftigation  in  an  unfavourable  point  of  view.  Of  our  tieatife,  though 
printe<i  above  two  years  ago,  he  has  not  yet  taken  any  notice. 

Soon  afterwards  Mr.  Girtanner  took  fome  pains  to  explain  the  refult  of  Mr.  Goettling's 
.experiments,  i<J/J.  1795,  No.  23,  by  fuppofing  the  azotic  gas  employed  had  contained 
fome  water,  which  was  decompofed  by  the  phofphorus.  He  did  not,  however,  take  the 
trouble  to  afcertain  by  experiments,  whether  phofphorus  does  really  give  light  in  azotic 
gas  thoroughly  freed  from  oxygen.  Mr.  Goettling  replied  to  this,  by  alledjing,  that  if 
the  water  which  exifts  diflblved  in  the  gafes  were  the  caufe  of  this  light,  the  phofphorus 
ought  alfo  to  emit  light  in  oxygen  gas,  which  according  to  his  experiments  did  not  take 
place.  Ibid.  No.  27.  He  afterwards  publlflied  a  more  ample  elucidation  of  the  fhort  an- 
fwer here  related  in  the  Almatiach  fuer  Scheide  Kuenjller,fjp^,  aflerting  that  the  luminous 
appearance  of  phofphorus  could  not  be  obtained  in  an  azotic  gas,  which  had  been  pro- 
cured by  a  long  continued  heating  of  the  phofphorus  in  atmofpheric  air,  becaufe  in  that 
cafe  the  phofphorus  mixes  with  the  azotic  gas,  and  prevents  it  from  maintaining  the  light. 
He  added,  that  the  gas  thus  circumftanced  is  found  to  recover  this  property  by  adding  a. 
few  drops  of  an  acid.  But  he  was  by  no  means  aware  that  his  obfervation  contained  a 
very  important  objedlion  againft  his  own  theory.  For  if,  according  to  that  theory,  azotic 
Vol.  II. — April  1798.  C  gai 


lo  CoHtroverfy  refpeBing  Phofpharus  in  Azotic  Gas, 

gas  be  really  a  compound  of  oxygen  and  light,  why  fliould  the  phofphorus,  on  being  mixed 
with  it,  ceafc  to  acl  on  its  oxygen  ?  Ought  it  not  rather  to  do  this  more  fpeedily  when 
the  cohefion  of  its  parts  is  deftroyed  ?  Bcfides  which,  the  addition  of  acids  is  not  fair, 
bccaufe  more  acid  than  is  neceflary  to  faturate  the  phofphorus  diflblved  in  it,  may  in  thi» 
■  way  become  united  with  the  azotic  gas.  Thus  I  have  found  that  the  phofphorus,  which 
does  not  fliine  in  pure  carbonic  acid  gas,  begins  to  give  light  in  that  medium  as  foon  as  a 
fmall  portion  of  acid  is  added.  The  anfwer  givci  by  Dr.  Jaeger  was  more  explicit.  He 
difcovered  in  particular,  that  the  volume  of  the  azotic  gas  was  never  diminilhed  when  the 
luminous  appearance  of  the  phofphorus  was  reproduced  by  means  of  acids.  Gren's  Neties 
Journal  der  Phjfik.   B.  11. 

It  was  not  long  after,  that  Profeflbr  Lampadius  publiftied  his  experiments  on  this  fub- 
jeft.  At  firft  he  feemed  to  find  every  thing  exa£lly  as  defcribed  by  Mr.  Goettling,  Ibid. 
B.  I. ;  but  foon  afterwards  he  made  the  interefting  difcovery,  that  by  a  careful  decompofi- 
tion  of  atmofpherical  air,  by  means  of  nitrous  gas,  azotic  gas  may  be  procured,  fo  free 
from  oxygen,  that  phofphorus  cannot  be  made  to  fliine  in  it.  Sammlutig  praB.  chemifch. 
Abhandl.  B.  I. 

Profeflbr  Hildebrandt  repeated  Mr.Gocttling's  experiments  with  the  greatelt  care.  CrelFs 
Annal.  1796,  B.  I.  Thefe  experiments  are,  no  doubt,  the  mofl;  exa£l  of  any  that  were 
made  for  this  purpofe.  He  has  perfedtly  confirmed  our  experiments.  He  has  proved 
this  beyond  all  queftion,  by  feveral  experiments,  of  which  I  fliall  mention  but  one. — In 
the  fame  azotic  gas  in  which  phofphorus  had  ceafed  to  fliine,  and  frefti  phofphorus  would 
not  afford  light,  the  luminous  appearance  took  place  as  foon  as  oxygen  gas  was  added.  But 
this  lafted  no  longer  than  till  the  latter  was  confumed  ;  for  there  was  precifely  as  much 
of  the  whole  volume  of  the  mixture  abforbed,  as  made  up  the  quantity  of  the  oxygen  gas 
that  was  added. 

There  are  feveral  well  known  papers  on  this  fubje£l:,  in  the  Annates  de  Chimie,  written  by 
French  chemifts  ;  but  none  of  their  authors  have  paid  the  leafl;  attention  to  what  has  been 
tranfa£led  on  this  matter  :  a  circumflance  which  I  have  thought  proper  to  be  mentioned 
in  this  place.  But  they  have  added  the  important  fa(fl,  that  phofphorus  is  foluble  in 
azotic  gas.  Probably  they  had  no  intelligence  of  what  has  been  written  about  it  in  Ger- 
many ;  and  as  this  appears  to  me  to  be  the  cafe  with  England,  I  confidered  it  of  fome  im- 
portance, to  give  the  ftiortefl:  poflible  view  of  the  chief  points  of  thefe  tranfadtions.  I 
Jiave  endeavoured  to  give  a  more  ample  detail  of  all  the  particular  fadls,  as  far  as  they 
were  known  down  to  Oftober  1 796,  in  a  work  of  mine,  equally  unknown  in  this  country : 
Nachtraege  z«  den  Grunzuegen  der  nettern  chemifchen  Theorit,  pag.  326 — 349,  in  which  the 
whole  extent  of  thefe  enquiries  may  be  feen  with  greater  eafe  by  the  fyftematical  arrange- 
ment of  the  experiments.  It  is  to  be  hoped  that  the  difpute  will  end  here,  and  that  the 
fafts,  (i.)  that  no  fliining  of  the  phofphorus  can  in  any  refpeA  take  place  in  fuch  azotic  gas 
as  is  quite  free  of  oxygen,  and  (a.)  that  it  cannot  be  made  to  fliine  unlefs  fome  other  body  be 
added  which  is  capable  of  aflbrding  ojcygen, — will  be  admitted  as  incontrovertiblyeft^abliflied. 

London,  Feb.  27,  1798- 

III.  On 


Nfit  Weather-- Injlrument,  ^  II 

III. 

On  M.  LAZOtVSK!*S  new-Barometer,  or  IV^nthcr  Injirument.     By  a  Correfpondeiit. 

To  Mr.  Nicholson,  Editor  tf  the  Philofophical  Journal. 
Sir,  Kendal,  Jan.  3:,  1798. 

i  H  E  following  experimental  cffay  is  too  trifling  to  require  an  introduftory  apology, 
were  it  not  for  the  high  name  of  Dr.  Hutton,  which  unavoidably  occurs  in  the  courfe  of  it, 
as  the  fubjedl  of  the  prefent  communication  was  firft  fuggefted  by  a  paragraph  in  his  Ma- 
thematical and  Philofophical  Didtionary,  publifhed  in  1795. 

When  any  thing  new  in  fcience  is  announced,  it  ought  to  be  made  public  as  generally  and  as 
fpeedily  as  poflTible.  In  thisTefpe£t  Dr.  Hutton  has  only  done  his  duty  as  a  compiler,  in  bring- 
ing the  Englifli  reader  acquainted  with  the  fuppofed  difcovery  of  a  new  inltrument  capable  of 
indicating  approaching  dianges  of  the  weather.  On  the  other  hand,  when  any  thing  novel  is 
communicated  to  the  lovers  of  fcience,  it  is  the  bufinefs  and  undoubted  right  of  every 
friend  to  enquiry,  not  to  receive  the  propofal  on  bare  authority,  but  to  fubjefl:  it  to  the 
teft  of  ar'Tument  and  experiment,  in  order  to  eftablifh  it  as  a  fa£l,  or  refute  it  as  an  error. 

Having  premifed  thus  much  in  my  own  vindication,  I  will  in  the  next  place  tranfcribc 
the  paragraph  alluded  to  above.  "  To  the  foregoing  may  be  added  a  new  fort  of  Baro- 
meter, or'  Weather  Inilrument,  by  the  found  of  a  wire.  This  is  mentioned  by  M. 
Lazowflci,  in  his  Tour  through  Switzerland  :  it  is  as  yet  but  in  an  imperfect:  {late,  and  was 
lately  difcovercd  there  by  accident.  It  feems  that  a  clergyman,  though  near-fighted,  often 
amufed  himfelf  with  firing  at  a  mark,  and  contrived  to  flretch  a  wire  fo  as  to  draw  the 
mark  to  him  to  fee  how  he  had  aimed.  He  obferved  that  the  wire  fometimes  founded 
as  if  it  vibrated  like  a  mufical  cord  ;  and  that  after  fuch  foundings,  a  change  always  enfued 
in  the  ftate  of  the  atmofphere,  from  whence  he  came  to  predi6l  rain,  or  fine  wea- 
ther. Sec.*" 

After  perufing  this  fingular  narrative,  I  found  myfelf  at  a  lofs  in  attempting  to  refer.thc 
difcovery  to  any  known  clafs  of  phenomena,  or  to  explain  it  by  the  afFedtions  of  the 
atmofphere,  confidered  as  depending  on  the  barometer,  ele£lricity,  or  even  the  hygrometer, 
without  admitting  a  fuppofition,  which  is  not  difcountenanced  by  the  preceding  report,  viz. 
that  one  end  of  the  wire  was  fixed  to  a  frame  of  wood,  while  the  other  end  was  (Iretched 
over  a  nail  or  metal  pin  in  the  fame  by  a  weight.  Under  thefe  circumltances,  it  appeared 
not  Impoffible,  that  the  wood-work  might  contrafl:  and  expand  from  fuccelTive  variations  in 
die  air's  humidity,  thereby  putting  the  pin  in  motion,  which  may  be  fuppofed  to  fcratch 
the  wire,  and  give  rife  to  the  found  in  queftion.  But  with  a  view  to  afcertain  if  a  vibratory 
motion  can  be  excited  in  metallic  firings  by  any  other  change  in  the  flate  of  the  atmofphere, 
I  fixed  a  number  of  copper  and  iron  wires,  in  the  beginning  of  April  1795,  in  an  open 
place  :  they  were  different  lengths,  from  three  to  fix  feet,  and  of  different  diameters, 
varving  from  the  thicknefs  of  a  fine  thread  to  the  fize  of  a  fmall  cord  ;  they  were  all 
ilretchedby  metal  pins,  refembling  thofe  ufed  in  a  h'arpfichord,  and  fo  difpofed  as  to  make 
various  angles  with  the  meridian  and  the  horizon.     The  apparatus,  being  thus  completed, 

'  See  Hutton's  Diftionary,  article  Barometer. 

G,  2  was 


l«         ^  .Weather-Injlrument,     Lolian  Harp,  ^c. 

was  carefully  attended  to  through  the  fummer,  particularly  when  the  afpeiSl  of  the  (fcy 
and  ftate  of  the  barorneter  feemed  to  predidt  an  approaching  change  ;  but  the  enquiry  was 
fruitlefs,  the  promlfed  found  was  never  heard ;  nor  did  any  other  circumftance  worthy 
notice  occur,  except  that  fome  of  the  fmalleft  wires  fnapped  occafionally  in  the  cold  nights 
of  the  fpring.  The  failure  of  this  experiment  feems  to  confirm  the  fuppofition  that  M. 
Lazowflci's  inftrument  is  at  bed  but  an  imperfeft  Hygrometerjand  that  it  does  notpromife 
any  new  difcovery  relative  to  the  properties  or  compofition  of  the  atmofphere  *.       J.  G. 


IV. 

Obfervathns  on  Scylla  and  Charyldh  t-      By  the  Jbbi  LazZARO  SfALLANZANI,  Profejfor  of 
Natural  Hijiory  at  Pavid,  F.R.S.    i^c.  ^c. 

Q 

KjCY'LLK  and  Charybdis,  according  to  the  fables  of  the  poets,  are  two  fea  monfters 
vvhofe  dreadful  jaws  are  continually  diftended  to  fwallow  unhappy  mariners  ;  the  one 
fituated  on  the  right,  and  the  other  on  the  left  extremity  of  the  Strait  of  Meflina,  where 
Sicily  fronts  Italy. 

Dextrum  Scylla  latus,  Ixvum  Implacata  Charybdis 
Obfidet :  atque  imo  barathri  ter  gurgite  vaflos 

*  The  paffage  in  Dr.  Huttou's  Diftionary  will  admit  of  the  fenfe,  that  the  obferver  (who  perhaps  nevsr 
took  notice  of  his  wire,  except,  when  bufied  in  the  arnufement  there  mentioned)  did  not  hear  any  Ipontancous 
found,  but  merely  perceived  a  mufical  vibration  at  certain  times  during  the  aft  of  drawing  the  mark  along 
the  wire,  which  mud  have  agitated  it.  This  might  arife  frointenfion,  by  fome  hygromctric  change  in  the 
fuuation  of  the  points  of  fupport.  It  may  be  remarked,  that  a  wire  for  the  ufe  the  clsrg^yuian  applied  it  to 
muft  have  been  much  longer  than  fix  feet;  and  that  it  was  probably  lefs  ftretched  than  the  wires  expoftd  by 
my  correfpondent. 

If  the  founds  were  fpontaneous,  the  faft  wjllbe  referable  to  the  Eolian  harp  of  Merfennus,  fioce  re-jnvcntad 
by  Ofwald.  The  inftrument  confifts  of  a  founding  board  about  two  fe(;t  or  more  in  length,  upon  which  ten 
or  twelve  (calgut)  firings  of  equal  length  but  different  thicknefs  are  tuned  in  unifon,  at  as  low  a  pitch  as  the 
fmalleft  of  the  ftrings  can  bear.  When  this  is  placed  in  a  current  of  air,  fuch  for  example  as  palTes  through  « 
w  indow  partly  opened,  it  emits  a  variety  of  contemporaneous  and  fuccelfive  tones,  which  from  their  thannes 
in  melody,  harmony,  and  fwell,  and  a  certain  wild  ftraiigenefs  in  the  whole  effeft,  rivet  tlie  attention,  and 
fometimes  afford  exqulfue  pleafure.  The  Eolian  harp  has  been  celebrated  by  Thomfon  and  other  poets.  I 
have  not  made  experiments  to  analyfe  its  nK)de  of  operation ;'  but  am  dilpofed  to  think,  ( i )  that  it  can  only- 
give  the  trumpet  notes  ;  (i)  that  the  note  to  be  afforded  by  any  one  ftring  depends  on  tlie  quantity  of  the 
impulfe  of  the  wind  being  greateft  near  one  end  of  that  ftring;  (3)  that  the  fame  quantity  and  direftion  of 
•  impulfe  will  agitate  a  longer  portion  of  the  flack  fmall  ftring  than  of  the  tenfer  thick  firing,  fo  that  in  the 
vibratory  fubdivifions  the  imallcr  ftring  will  give  the  graver  tone;  (4)  that  a  powerful  tone  drawn  ft-om  one 
ftring  may  difpofc  the  other  ftrings  to  vibrate  unifons,  fifths,  thirds,  oftav'es,  and  other  concords,  more  or  lefs. 
remote  according  to  the  circumftances. 

If  M.  Lazowfki's  wire  aaod  upon  the  principle  of  the  Eoliao  harp,  it  might  beprefMnKd  that  xh&  recuJrenw 
%%  well  »s  the  nature  of  the  found  emitted  would  be  governed  by  the  fores  and  angle  of  direftioa  of  the  wind  ; 
and,  if  fo,  much  would  depend  on  the  expofur^  the  direftion  and  the  tenfion  of  the  wir,e.  Whether  on  this 
fuppofition  it  could  afford  any  more  certain  indication  of  approaching  change  of  weather,  than  is  tfually  ob- 
tained from  a  finiplc  obfervation  by  the  wind  vane,  muft  be  decided  by  fafts,  if  fuch  flioultl  hereafter  appear.     N. 

t  Travels  in  the  Two  Sicilici.    ^nglilh  Traofl.  IV.  168. 

i  Sorbet 


Defcription  of  Scylla  and  Charybdis.  •  13 

Sorbet  in  abruptum  fluclus,  rurfufque  fub  auras 
Erigit  alternos,  et  fidera  vcrberat  unda. 
At  Scyllatn  caecis  cohibet  fpelunca  latebris, 
Ora  exertantem,  et  naves  in  faxa  trahentem. 
Prima  homlnis  facies,  et  pulchro  pedlore  virgo 
Pube  lenus  :   pollrema  immani  corpore  priflis, 
Delphindn;  caudas  utero  commifla  luporum. 

ViRG.  Mndd.  Lib.  IIL       - 


I  hides  :    "j 

f 

he  tides,   J 


Far  on  the  right  her  dogs  foul  Scylla  hides 

Charybdis  roaring  on  the  left  prefides, 

And  in  her  greedy  whirlpool  fucks  the 

Then  fpouts  them  from  below :  with  fury  driv'n 

The  waves  mount  up,  and  wa£h  the  face  of  heav'n. 

But  Bcylla  from  her  den  with  open  jaws 

The  finding  veflel  in  her  eddy  draws, 

Then  daflies  on  the  rocks.  A  human  face 

And  virgin  bofom  hide  her  tail's  difgrace  ; 

Her  parts  obfcene  below  the  waves  defcend 

With  dogs  enclos'd,  and  in  a  dolphin  end.  Dryden. 

I  have  no  difficulty  in  availing  myfelf  of  tlie  defcription  of  a  poet  in  a  work  dedicated  to 
the  inveftigation  of  truth,  nor  Ihall  I  hefitate  to  cite  iimilar  paffages  fron)  another  poet  } 
fince,  however  exaggerated  thefe  may  be  by  the  glowing  colours  of  imagination,  they  con- 
tain truth,  and  afford  a  fubjedl:  for  interefting  enquiries. 

I  ftiould  have  thought  myfelf  to  have  merited  the  greateft  cenfure,  if,  when  I  was  in  the 
ftrait  of  Meffina,  I  had  not  vifited  two  places  of  which  fo  much  has  been  written,  and  which 
have  been  rendered  fo  famous  by  the  numerous  (hipwrecks  they  have  occafioned. 

I  firft  proceeded  in  a  fmall  boat  to  Scylla.  This  is  a  lofty  rock,  diftant  twelve  miles 
from  Meffina,  which  rifes  almoft  perpendicularly  from  the  fca  on  the  fliore  of  Calabria,  and. 
beyond  which  is  the  fmall  city  of  the  fame  name.  Though  there  was  fcarcely  any  wind,  I 
began  to  hear,  two  miles  before  I  came  to  the  rock,  a  murmur  and  noife  like  a  confufed 
barking  of  dogs,  and,  on  a  nearer  approach,  readily  difcovered  the  caufe.  This  rock,  in  its 
lower  parts,  contains  a  number  of  cavcrns,onc  of  the  largeft  of  which  is  called  by  the  peo- 
ple there  Dragara.  The  waves,  when  in  the  leafl  agitated,  rulhing  into  thefe  caverns, 
break,  dafli,  throw  up  frothy  bubbles,  and  thus  occafion  thefe  various  and  multiplied 
founds.  I  then  perceived  with  how  much  truth  and  refcmblance  of  nature  Homer  and 
Virgil,  in  their  pcrfonifications  of  Scylla,  had  pourtrayed  this  fcene,  by  defcribing  the 
monfter  they  drew  as  lurking  in  the  darknefs  of  a  vaft  cavern,  furrounded  by  ravenous 
barking  maftifFs,  together  with  wolves  to  increafe  the  horror  : 

T«{  nroi  fuv»  /*cv  ckti]  ffmihaxoi  noytMi 

Th/Hm^  ■  '    HoM.  OdyfCXII. 

.    "  Here 


14  .  JticUnt  gild  prtfdit  Stait  if  Sc^Ua  and  Char^'hdh, 

Here  Scylla  bellows  from  her  dire  abodes, 
Tremendous  peft  !  abhorr'd  by  man  and  gods ! 
Hideous  her  voice,  and  with  lefs  terrors  roar 
The  whelps  of  lions  in  the  midnight  hour !  Pope. 

The  Greek  poet,  when  he  pourtrays  the  rock  which  is  the  habitation  of  Scylla,  finifhes 
the  picture  higher  than  the  Latin,  by  reprefenting  it  as  fo  lofty  that  its  fummit  is  conti- 
nually wrapped  in  the  clouds,  and  fo  fteep,  fmooth  and  flippery,  that  no  mortal  could  af- 
cend  it,  though  he  had  twenty  hands  and  twenty  feet. 

'0(  SSe  Jua  trxoTTEXoi,  o  |tt£v  ougavov  tvpuv  mam 
Kuantif  10  /xEv  ownoT  e^aii,  owJettot'  ai^pt: 

KtiVOU  EXEl    M^U<pW,   cut'    £V  Sff £1    OVt'  £V  O'TTU^lf. 

Oi/Je  Kiv  aixBam  Ppolof  m»)f,  ov  xcSaQam, 
OvV  £1  hi  X^'?^i  y^  tiMotn  xai  woh;  titv, 
nilpyiyapMitri'ai^i^srneiwtx,  HoM.  OdyfT.  Xll. 

High  in  the  air  the  rock  its  fummit  {hrouds 

In  brooding  tempefts  and  in  rolling  clouds  ; 

Loud  ftorms  around  and  mifls  eternal  rife, 

Beat  its  bleak  brow  and  intercept  the  fkies. 

When  all  the  broad  expanfion,  bright  with  day, 

Glows  with  th'  autumnal  or  the  fummer  ray  ; 

The  fummer  and  the  autumn  glow  in  vain. 

The  flcy  for  ever  low'rs,  for  ever  clouds  remain. 

Impervious  to  the  ftep  of  man  it  Hands, 

Though  borne  by  twenty  feet,  though  arm'd  with  twenty  hand«. 

Smooth  as  the  polifli  of  the  mirror  rife 

The  flippery  fides,  and  (hoot  into  the  fkies.  Pope. 

Such,  three  thoufand  years  ago,  or  nearly  fo,  appeared  the  rock  of  Scylla,  according  to 
the  obfervation  of  Homer  j  and  fuch  is  nearly  its  appearance  at  this  day. 

The  accuracy  of  this  truly  <'  firft  great  painter  of  antiquity,"  which  has  likcwife  been  ob- 
fervcd  by  fcientific  travellers  in  other  defcriptions  which  he  has  given,  fhews  that  the  level 
of  the  waters  of  the  fea  was  at  that  time  at  nearly  the  fame  height  as  at  prefent,  fince,  had 
it  funk  only  a  few  fathom,  it  muft  have  left  the  foot  of  the  rock,  which,  according  to  my 
obfervations,  is  not  very  deep,  entirely  dry.  And  this  I  confider  as  one  among  feveral  ftrong 
arguments,  that  the  moft  remarkable  finkings  of  the  fea  are  anterior  to  the  time  of  Homer.. 

Such  is  the  fituation  and  appearance  of  Scylla :  let  us  now  confider  the  danger  it  pcca» 
fions  to  mariners.  Though  the  tide  is  almoll  imperceptible  in  the  open  parts  of  the  Medi- 
.tcrranean,  it  is  very  ftrong  in  the  ftrait  of  Meffina,in  confequence  of  the  narrownefs  of  the 

channel," 


.        Danger  of  Mariners  in  tie  Vicinity  of  Scylla.  1 5 

channel,  and  is  regulated,   as  in  other  places,  by  the  periodical  elevations  and  dcpreflion 
of  the  water.     Where  the  flow  or  current  is  accompanied  by  a  wind  blowing  the  fame 
way,  veffels  have  nothing  to  fear,  fince  they  either  do  not  enter  the  ftrait,  both  the  wind  and 
the  ftream  oppofing  them,  but  call  anchor  at  the  entrance;  or,  if  both  arc  favourable,  en- 
ter on  full  fail,  and  pafs  through  with  fuch  rapidity  that  they  fcem  to  fly  over  the  water. 
But  when  the  current  runs  from  fouth.  to  north,  and  the  north  wind  blows  hard  at  the 
fame  time,  the  fliip  which  expected  eafily  to  pafs  the  ftrait  with  the  wind  in  its  ftern,  on 
its  entering  the  channel  is  refifted  by  the  oppofite  current,  and,  impelled  by  two  forces  in 
contrary  directions,  is  at  length  dalhed  on  the  rock  of  Scylla,  or  driven  on  the  neighbouring 
-  fands  ;    unlefs  the  pilot  fliall  apply  for  the  fuccour  neceflary  for  his  prefervation.     For,  to 
give  afliftance  in  cafe  of  fuch  accidents,  four-and-twenty  of  the  ftrongeft,  boldeft  and  moft 
experienced  failcrs,  well  acquainted  with  the  place,  are  ftationed  night  and  day  along  the 
ihore  of  Meflina  ;  who,  at  the  report  of  guns  fired  as  fignals  of  diftrefsfrom  any  veflel,  haf- 
ten  to  its  affiftance,  and  tow  it  with  one  of  their  light  boats.     The  current,  where  it  is 
'ftrongeft,  does  not  extend  over  the  whole  ftrait,  but  winds  through  it  in  intricate  meanders, 
with  the  courfe  of  which  thefe  men  are  perfectly  acquainted,  and  are   thus  able  to  guide 
the  ftiip  in  fuch  a  manner  as  to  avoid  it.    Should  the  pilot,  however,  confiding  in  his  owa 
Ikill,  contemn  or  neglefl  this  affiftance,  however  great  his  ability  or  experience,  he  would 
run  the  moft  imminent  rilk  of  being  fliipwrecked.     In  this  agitation  and  confli£l  of  the 
waters,  forced  one  way  by  the  current,  and  driven  in  a  contrary  diredlion  by  the  wind,  it  is 
ufelefs  to  throw  the  line  to  difcover  the  depth  of  the  bottom,  the  violence  of  the  current 
frequently  carrying  the  lead  almoft  on  the  furface  of  the  water.     The  ftrongeft  cables, 
though  fome  feet  in  circumference,  break  like  fmall  cords.     Should  two  or  three  anchors 
be  thrown  out,  the  bottom  is  fo  rocky  that  they  either  take  no  hold,  or,  if  they  ftiould,  arc 
foon  loofened  by  the  violence  of  the  waves.     Every  expedient  afforded  by  the  art  of  navi- 
gation, though  it  might  fucceed  in  faving  a  fliip  in  other  parts  of  the  Mediterranean,  or 
even  the  tremendous  ocean,  is  ufelefs  here.     The  only  means  of  avoiding  being  daftied 
againft  the  rocks  or  driven  upon  the  fands  in  the  midft  of  this  furious  conteft  of  the  winds  • 
and  waves,  is  to  have  recourfe  to  the  flcill  and  courage  of  thefe  Meffinefe  feamen. 

In  proof  of  the  truth  of  this  aflertion,  I  might  adduce  many  inftances  related  to  me  by 
perfons  deferving  of  credit.  But  I  was  myfelf  an  eye-witnefs  to  the  fituation  of  a  trading 
veffel  from  Marfeilles,  which  had  one  day  entered  the  Strait  by  the  mouth  on  the  north 
fide,  at  the  time  that  I  was  on  a  hill  looking  towards  the  fea.  The  current,  and  a  north 
wind  which  then  blew  ftrong,  being  both  in  its  favour,  the  veffel  proceeded  under  full  fail 
into,  and  had  paffed  one  half  of  the  Strait,  when,  on  a  fudden,  the  Iky  became  overcaft 
with  thick  clouds,  and  violent  gufts  of  wind  arofe,  which  in  an  inltant  changed  the  direc- 
tion of  the  current,  and  turned  up  the  fea  from  its  bottom.  The  mariners  had  fcarcely 
time  to  hand  the  fails,  while  the  furious  waves  broke  over  the  Ihip  on  every  lide.  Whether 
they  merely  followed  the  pradtice  ufual  with  fliips  in  diftrefs,  or  whether  they  were  ac- 
quainted with  the  laudable  cuftom  of  the  Meffmefe,  I  cannot  fay;  but  they  fired  two  guns  j 
immediately  upon  which  one  of  the  barks  employed  on  this  fervice  haftened  to  the  affift- 
ance of  the  diftreffed  veffel,  and,  taking  it  in  tow,  began  to  make  every  exertion  to  carry  it 
fafely  into  the  harbour. 

If  I  had  ten  with  fear  and  fliuddering  the  danger  of  the  failors  on  board  the  veffel^^ 

which . 


l6  -  Anc'ienl  Jccounts of  Charyhdls.  ^ 

which  I  expeftcd  every  moment  would  be  fwallowed  up  in  the  waves ;  I  beheld  with 
wonder  and  pleafure  the  addrefs  and  bravery  of  the  MeiTu'iefe  mariners,  who  had  under- 
taken to  fleer  fefely  through  fo  ftormy  a  fea  the  fhip  entruiled  to  their  care.  1  hey  extri- 
cated it  from  the  current,  which  impelled  it  towards  deftruflion  ;  changed  the  helm  to  this 
fide,  or  to  that;  reefed  or  fet  the  fails,  as  the  wind  increafed,  or  abated;  avoided  the 
impetuous  fhocks  of  the  waves,  by  meeting  them  .with  the  prow,  or  oppofmg  to  them  the 
fide,  as  either  method  appeared  mod  proper  to  break  their  violence;  and  by  thefe  and  other 
manceuvres,  which  I  am  unable  to  defcrlbe,  thefe'brave  mariners,  amid  this  dreadful  con- 
flict of  the  fea  and  the  wind,  fucceeded  in  their  undertaking,  and  brought  the  veflel  fafe 
into  the  harbour. 

But  enough  of  Scylla : — we  will  now  proceed  to  Charybdis.  This  is  fituated,  within  the 
Strait,  in  that  part  of  the  fea  which  lies  befween  a  projection  of  land  named  Punta  Seccti, 
and  another  projection  on  which  ftands  the  tower  called  Lantcrna,  or  the  Hght-houfe,  si 
light  being  placed  at  its  top  to  guide  veffeJs  which  may  enter  the  harbour  by  night. 

On  confulting  the  authors  who  have  written  of  Charybdis,  we  find  that  tliey  all  fuppofed 
it  to  be  a  whirlpool.  The  firft  who  has  afferted  this  is  Homer,  who  has  reprefented  Cha- 
rybdis as  a  monller,  which  three  times  in  a  day  drinks  up  the  water,  and  three  times  vomits 
it  forth. 

— — — —  s(a  Xafu?(Ji;  avafpoiS^si  [j,sXav  loui^, 

TpiS  i^ev  ya.0  r'aytrja-iv  tit  rJ^oi.a7i,  rpts  S'a.va-fpoi'SSBi 

AciMx.  ,  HoM.Odyir.  XIL 

Beneath  Charybdis  holds  her  boifteroiis  reign 
'Midft  roaring  whirlpools,  and  abforbs  the  main ; 
Thrice  in  her  gulphs  the  boiling  feas  fubfide, 
Thrice  in  dire  thunders  {he  refunds  the  tide.         Pope. 

The  defcription  of  Virgil  above  cited,  differs' from  that  of  Homer  only  in  placing  a  deep 
gulph  below.  Strabo,  Ifidorus,  Tzetzes,  Hefychius,  Didymus,  Euflathius,  &c.  repeat  the 
fame.  The  Count  de  Buffon  adopts  the  idea  of  Homer  in  full  confidence,  and  places 
Charybdis  among  the  moll  celebrated  whirlpools  of  the  fea.  "  Charybdis,  in  the  ftrait  of 
Meffina,  abforbs  and  rejeCls  the  water  three  times  in  twenty-four  hours*."  Strabo  tells 
us,  that  the  fragments  of  ihips  fwallowed  up  in  this  whirlpool  are  carried  by  the  current 
to  the  (horc  of  Tauromenium  (the  prefentTaormina)  thirty  miles  diftant  from  Charybdisf. 
In  confirmation  of  this  tradition,  an  amufing  though  tragical  anecdote  is  related  of  one 
Colas,  a  Meffmean  diver,  who,  from  being  able  to  remain  a  long  time  under  water,  had 
acquired  the  furname  of  Pef-e  (the  fifh).  It  is  reported  -that  Frederic,  king  of  Sicily,  com- 
ing to  Meflina  purpofely  to  fee  him,  made  trial  of  his  abilities  with  a  cruel  kind  of  liberality, 
.by  throwing  a  golden  cup  into  Charybdis,  which  if  he  brought  up  was  to  be  the  reward 
K>f  his  refolution  and  dexterity.  The  hardy  diver,  after  having  twice  aftoniflied  the  fpec- 
•  tators  by  remaining  under  water  a  prodigious  length  of  time,  when  he  plunged  the  third 
^time  appeared  no  more;  but,  fome  days  after,  his  body  was  found  on  the  coail,  near 
Taprnaina. " 

•  Buffon,  Hi  ft.  Nat.  tom.ii.  in  iimo. 

From 


^  V 


^v>^.  Modern  State  of  Charyhdis.  ■  1 7 

From  the  authorities  here  adduced,  it  is  evident  that  Charyhdis  has  hitherto  been  con- 
fidered  as  a  real  whirlpool,  by  both  ancient  and  modern  travellers  who  have  given  any  ac- 
count of  it. 

As  I  was  therefore  fo  near  to  this  celebrated  place,  I  determined  to  endeavour  to  afcer- 
tain,  if  poflible,  what  it  really  is.  It  is  diftant  from  the  (here  of  Meflina  about  feven  hun- 
dred and  fifty  feet,  and  is  called  by  the  people  of  the  country  Galofaro,  not  from  the  agita- 
tion of  the  waves  as  fome  have  fuppofed,  but  from  xahoi  and  ^afo? ;  that  is,  the  beautiful- 
toiver,  from  the  light-houfe  eredled  near  it  for  the  guidi-nce  of  veflels.  The  phenomenon 
of  the  Calofaro  is  obfervable  when  the^current  is  defcending ;  for,  when  the  current  fets  in 
from  the  north,  the  pilots  call  it  the  defcending  rema*,  or  current ;  and  when  it  runs  from  the 
fouth,  the  nfcendtng  rema.  The  current  afcends  or  defcends  at  the  rifing  or  fetting  of  the 
moon,  and  continues  for  fix  hours.  In  the  interval  between  each  afcent  or  defcent,  there 
is  a  calm  which  lafts  at  lead  a  quarter  of  an  hour,  but  not  longer  than  an  hour.  After- 
wards, at  the  rifing  or  fetting  of  the  moon,  the  current  enters  from  the  north,  making 
various  angles  of  incidence  with  the  flicre,  and,  at  length  reaches  the  Calofaro;  This 
delay  fometimes  continues  two  hours.  Sometimes  it  immediately  falls  into  the  Calofaro, 
and  then  experience  has  taught  that  it  is  a  certain  token  of  bad  weather. 

As  I  was  afiured  by  the  pilots  mod  experienced  in  this  pradical  knowledge,  that  there 
was  no  danger  in  vifiting  the  Calofaro,  I  refolved  to  avail  myfelf  of  the  opportunity.  The 
bark  in  which  I  made  the  excurfion  was  managed  by  four  expert  mariners,  who,  perceiving 
me  fomewhat  intimidated  as  I  approached  the  place,  encouraged  me,  and  aflured  me  they 
would  give  me  a  very  near  view  of  the  Calofaro,  and  even  carry  me  into  it  without  the 
leaf!  danger. 

When  I  obferved  Charyhdis  from  the  fhore,  it  appeared  like  a  group  of  tumultuous  wa- 
ters ;  which  group,  as  I  approached,  became  more  extenCve  and  more  agitated.     I  was 
carried  to  the  edge,  where  I  flopped  fome  time  to  make  the  requifite  obfervations,  and  was 
then  convinced  beyond  the  fhadow  of  a  doubt,  that  what  I  faw  was  by  no  means  a  vortex, 
.  or  whirlpool. 

Hydrologlfts  teach  us,  that  by  a  whirlpool  in  a  running  water  -wt  are  to  underftand 
that  circular  courfe  which  it  takes  in  certain  circumftances  ;  and  that  this  courfe,  or  Yevo- 
lution,  generates  in  the  middle  a  hollow  inverted  cone,  of  a  greater  or  lefs  depth,  the  Inter- 
nal fides  of  which  have  a  fpiral  motion.  But  I  perceived  nothing  of  this  kind  in  the 
Calofaro.  Its  revolving  motion  was  circumfcribed  to  a  circle  of  at  mofl  an  hundred  feet 
in  diameter  ;  within  which  limits  there  was  no  incurvation  of  any  kind,  nor  vertiginous 
motion,  but  an  inceflant  undulation  of  agitated  waters  which  rofe,  fell,  beat,  and  daflied  on 
each  other.  Yet  thefe  irregular  motions  were  fo  far  placid,  that  nothing  was  to  be  feared 
in  palling  over  the  fpot,  which  I  did  ;  though  our  little  bark  rocked  very  much  from  the 
continual- agitation,  fo  that  we  were  obliged  conftantly  to  make  ufe  of  our  oars  to  prevent 
its  being  driven  out  of  the  Calofaro.  I  threw  fubftances  of  different  kinds  into  the  ftream. 
Such  as  were  fpeclficaliy  heavier  than  the  water  funk,  and  appeared  no  more  ;  thofe  which 

*  I  have  obferved  that  at  Medina,  as  well  as  in  other  parts  of  Sicily,  words  of  the  Greek  language,  wliich  was 
once  that  of  this  ifland,  are  ftill  retained.  Thus  the  word  rema  derived  from  /««;*«,  a  flowing,  or  ftream,  is 
ufcd  to  fignify  the  current  of  this  ftrait. 

Vol.  II. — April  1798.  D  were 


1 8  State  of  Charyhdis. 

were  lighter  remained  on  the  furface,  but  were  foon  driven  out  of  the  revolving  circle  by- 
the  agitation  of  the  wrater. 

Though  from  thefe  obfervations  I  was  convinced  that  there  was  no  gulph  under  the 
Calofaro  ;  as  otherwife  there  would  have  been  a  whirlpool,  which  would  have  carried  down 
into  it  the  floating  fubftanccs  ;  I  determined  to  found  the  bottom  with  the  plummet,  and 
found  its  greateft  depth  did  not  exceed  five  hundred  feet.  I  was  likewife  informed,  to  my 
no  fmall  furprlfe,  that  beyond  the  Calofaro,  towards  the  middle  of  the  ftrait,  the  depth 
was  double. 

I  could  not  therefore  but  conclude  from  thefe  fafls,  that  at  that  time  there  was  no 
whirlpool  in  Charybdis.  I  fay  at  that  t'nm,  fince  the  cafe  might  be  very  different  when  the 
fea  waa^tempeftuous.  I  therefore  made  enquiry  relative  to  this  of  the  pilots,  thofe,  efpe- 
cially,  who,  from  their  tried  experience,  were  appointed  by  the  public  to  give  affiflance  in 
ftorms  to  foreign  veflels,  and  who  had  frequently  feen  Charybdis  in  its  greateft  fury.  The 
following  is  the  fubftance  of  the  anfwers  they  gave  me  : 

When  the  current  and  the  wind  are  contrary  to  each  other,  and  both  in  their  greateft 
violence,  efpecially  when  the  fcilocco,  or  fouth  wind,  blows  j  the  fwelling  and  dafliing  of 
the  waves  within  the  Calofaro  is  much  ftronger,  more  impetuous,  and  more  extenfive.  It 
then  contains  three  or  four  fmall  whirlpools,  or  even  more,  according  to  the  greatnefs  of 
its  extent  and  violence.  If,  at  this  time,  fmall  veflHs  are  driven  into  the  Calofaro  by  the 
currenty.'or  the  wind,  they  are  feen  to  whirl  round,  rock,  and  plunge  ;  but  are  never  drawn 
down  into  the  vortex.  They  only  fink  when  filled  with  water,  by  the  waves  beating  over 
them,  when  veflels  of  a  larger  fize  are  forced  into  it,  whatever  wind  they  have  they  cannot 
extricate  themfelves;  their  fails  are  ufelefs;  and  after  having  been  for  fome  time  tofled, 
about  by  the  waves,  if  they  are  not  affifted  by  the  pilots  of  the  country,  who  know  how  to 
bring  them  out  of  the  courfe  of  the  current,  they  are  furioufly  driven  upon  the  neighbour- 
ing fhore  of  the  Lanterna,  where  they  are  wrecked,  and  the  greater  part  of  their  crews 
perifli  in  the  waves  *. 

If  we  confider  maturely  thefe  fa£ls,  we  (hall  find  that  a  great  part  of  what  has  been» 
^written  relative  to  Charybdis  is  very  erroneous.  We  have  feen  how  many  authors,  from ' 
Homer  to  the  prefcnt  time,  have  defcribed  it  as  a  real  whirlpool,  or  great  gulph  revolving  in 
itfelf,  within  the  circumference  of  which  (hould  any  fhip  enter,  it  is  immediately  drawn 
to  the  centre  and  fwallowed  up.  When  the  current  is  dying  away,  or  when  there  is  no 
current,  this  defcription  has  no  rcfemblance  to  truth.  Charybdis  is  then  perfeftly  inno- 
cent, as  I  have  been  fully  convinced  by  my  own  obfervations  j  and  even  when  it  is  agitated 

•  The  following  account  of  the  fliipwreck  of  a  vclTel  in  the  Calofaro  was  fent  me,  after  my  return  from 
Sicily,  by  the  Abbate  Granofrom  Melfina  : 

"  About  three  vveeks  ago,  we  were  fpc£lators  of  the  finking  of  a  Neapolitan  polacca  in  the  Calofaro,  on  its 
paffage  from  Fuglia,  laden  with  corn.  A  moft  violent  fouth-eafterly  wind  blew,  and  the  veflll,  with  all  fails 
fet,  endeavoured  to  reach  the  harbour,  ftanding  off  from  the  Calofaro;  but  the  head  of  the  current  from  the 
entrance  by  the  faro  took  her,  and  drew  her  impetuoufly  into  it ;  where,  without  being  able  to  make  u(e  of 
her  fails,  fhe  remained  for  fome  time  tolTed  about  by  the  waves,  which  at  length,  cither  breaking  over  her,  or 
opening  her  fides  by  their  furious  beating,  fent  her  to  the  bottom.  The  crew,  however,  and  a  part  of  the  cargo 
were  faved  by  the  fpeedy  affiftance  given  by  our  mariners  in  two  fmall  barks,  who  had  the  courage  to  encounter 
the  danger.  You  will  perceive  from  this,  in  what  manner  the  waves  may  fink  fliips  in  Charybdis,  without  the 
ileceflity  of  fuppolbg  a  whirlpool." 

and 


Slate  of  CharyhcTts.  '  %^ 

and  dangerous,  it  ftill  contains  no  incavation,  or  gulph  of  tlie  nature  of  a  vortex ;  but 
merely  a  ftrong  agitation  and  dafliing  of  Its  waves,  which  produces  thofe  fmall  whirlings 
of  its  waters,  which  are  only  accidental  and  not  to  be  feared.  So  far  llkewife  is  Charybdis 
from  drawing  to  itfelf  and  fwallowing  veflels,  that  it  rather  repels  them,  and  throws  them 
to  a  diftance. 

This  error  has  arlfen  like  many  others  with  refpeiH:  to  the  produftlons  of  nature. 
Homer,  in  relating  the  voyage  of  Ulyfles  through  the  Strait  of  Mefllna,  was  the  firft  who 
defcribed  Charybdis  as  an  Immenfe  vortex,  which  abforbs  and  rejects  the  water,  and  the 
fhlps  that  approach  it ;  exemplifying  his  account  by  the  fate  of  fome  of  the  companions 
of  his  hero,  who  were  carried  away  by  the  whirlpool.  The  writers  who  came  after  him, 
whether  poets,  orators,  hiftorlans,  or  geographers,  have  followed  him  in  this  defcription, 
without  any  one  of  them  taking  the  pains  to  repair  to  the  place  and  examine  it  hlmfelf» 
Even  Fazello  the  Sicilian,  who  was  fo  induftrious  in  afcertaining  fadis,  and  whofe  accounts 
of  his  country  are  fo  accurate,  clearly  {hews  in  his  defcription  of  Charybdis,  that  he  had 
never  obferved  it  himfelf  j  and  concludes  his  narration  with  the  erroneous  fuppofitioii 
above  cited,  that  the  things  fwallowed  up  by  Charybdis  are  conveyed  by  fubmarlne  currents 
to  the  fliores  of  Taormina. 

Among  all  who  have  written  on  this  fubjeft,  we  only  find  Cluverius  who  feems,  at 
Jeaft  at  firft  view,  to  have  vifited  the  place.     I  fliall  tranfcribe  his  words  : 

"  Ego  fane,  cum  Charybdis  liofcendse  gratia  aliquot  dies  Meflana  fubfifterem,  et  ab 
hominibus  ejus  loci,  maxime  vero  nautls,  non  Siculls  modo,  fed  et  Belgis,  Britannis  et  Gallis, 
■qui  hoc  fretum  frequentes  navigant,  dlligentius  earn  rem  fclfcltarer,  nihil  omnino  certi 
ipfis  perdifcere  potui,  adeo  fcilicet  totum  negotlum  omnibus  obfcurum  et  incognitum  erat. 
Tandem  tamen  reperl  Charybdim,  quse  incolis,  patrils  vocabulis,  dicitur  Calofaro,  fub  prse- 
difta  ad  Mefianenfem  portum  pharo  efle  mare  rapidc  fluens,  atque  in  vortices  a£tum  :  quod 
non  <rf(;  £7r'  iifiali  ut  tradit  Homerus,  id  edjingulis  diebus  ier,  abforbet  ingenti  gurgite,  revo- 
mitque  aquas,  fed  quoties  vehementlori  flu£lu  fretum  comltatur." 

*'  I  remained  fome  days  at  MeGina,  with  a  view  to  obtain  fome  information  relative  to 
Charybdis ;  but  though  I  made  every  enquiry  of  the  people  of  the  place,  and  principally 
•thefailors,  not  the  Sicilian  only,  but  the  Italian,  Dutch,  Englifh,  and  French,  who  fre- 
quently navigate  that  Strait,  I  could  learn  nothing  fatisfaftory,  fo  little  was  known  by  them 
on  the  fubje£i.  At  length  however  I  found  Charybdis,  which  the  natives  call  Calofara^ 
under  the  lighthoufc  before  mentioned  near  the  Jiarbour,  to  be  a  fea  rapidly  flowing,  and 
forming  vortices.  It  does  not  abforb  the  waters  in  its  vaft  gulph,  and  rejefl;  them  thric< 
in  a  dayy  as  Homer  tells  us  ;  but  as  often  as  the  fea  runs  high  in  the  Strait." 

From  the  exprefllon  "  I  found  Charybdis"  we  miglit  be  induced  to  believe,  that  he 
made  his  obfervations  on  the  fpot.  It  is  certain  however  that  he  does  not  explicitly  tell 
us  fo :  and  when  treating  of  a  phenomenon,  of  which  he  was  fo  anxious  to  obtain  an 
accurate  knowledge,  which  he  could  not  procure  even  from  the  Meffinefe  failors,  it  is 
ftrongly  to  be  prefumed,  that  he  would  not  have  fupprcffed  a  circum.ftance  of  that  import- 
ance. As  Charybdis  may  be  feen  from  the  (hore,  if  he  only  went  thither  and  turned  his 
eyes  towards  it,  he  might  with  truth  aflert  that  he  had  difcovered  It.  The  other  adjundls 
to  his  account,  that  Charybdis  is  a  rapid  fea,  and  Ltmt  it  abforbs  and  rejetls  tlie  water  in 

Da  a  ftorm, 


20  Scylla  and  CJjarytclis. 

a  dorm,  convince  me  that  he  had  not  a  juft  idea  of  it,  but  fatisfied  himfelf  with  the  old 
tradition  concerning  Charybdis. 

It  may  be  obferved,  that  the  fituation  of  Charybdis,  as  it  has  been  hitherto  defcribed, 
does  not  exaftly  agree  with  that  afligned  it  by  Homer.  Let  us  refer  to  the  poet.  The 
goddcfs  Circe  gives  the  following  diredtions  to  Ulyfles,  with  refpedt  to  the  navigation  of 
tlic  Strait  of  Meffina  : 

'Oi  St  Svw  iTKOiteMt,  'o  ^iv  ovpayov  eii^vv  ikolvsi'  .  .  . 

Toy  S"  itepoy  (TKMBXoy/J^a.u^aKujrEfw  0']i&i  OS'jircrsv, 

IlAijcriov  aXXr^Xuiv,  y.M  Kiv  Siois-e^CB^cc;. 

TtjU  S'sv  spnso;  sari  fj-Eyix,;  ^uAokti  te&tjXuji, 

Tw  J'  vTto  Siec  Xa^ufJif  arapfoi^hi  ^sAav  vSuip,  HoM.  Odyfl".  XII. 

High  o'er  the  main  two  rocks  exalt  their  brow  ... 

Clofe  by,  a  rock,  of  lefs  enormous  height 

Breaks  the  wild  waves,  and  forms  a  dangerous  ftreight; 

Full  on  its  crown  a  fig's  green  branches  rife. 

And  (hoot  a  leafy  foreft  to  the  Ikies: 

Beneath,  Charybdis  holds  her  boifterous  reign 

'Midft  roaring  whirlpools,  and  abforbs  the  main.         Pope. 

The  firfl:  of  the  rocks  here  mentioned  by  Homer  is  Scylla,  which  he  defcribes  at  length  j 
and  near  the  other,  according  to  this  poet,  Charybdis  is  fituated.  The  diftance  from  one 
of  thefe  rocks  to  the  other  is  an  arrow's  flight,  xai  xtv  Jioirwtreiflts,  which  does  not  at  all 
accord  with  the  prefent  fituation  of  Scylla.  How  are  we  to  explain  this  difagreement  ? 
Shall  we  fay  that  Homer,  availing  himfelf  of  the  licence  in  which  poets  are  indulged,  has 
fpoken  hyperbolically  .''  I  know  not  whether  the  connoifleurs  in  poetry  will  permit  fuch  a 
licence.  Or  fliall  we  fuppofe  that  Charybdis  was  once  much  nearer  to  Scylla  ;  but  that  in 
a  long  feries  of  ages  it  has  changed  its  place,  and  removed  under  Mefllna  ?  Such  a  fuggeftion 
might,  perhaps,  be  favourably  received,  if  in  remote  times  any  confiderable  change  had 
taken  place  in  the  Strait :  but  we  know  not  of  any  ;  and  it  is  not  probable,  that  a  change 
fo  remarkable  as  the  removal  of  Charybdis  from  its  place  would  have  been  pafled  over  in 
Clence  by  Sicilian  writers.  Within  the  prefent  century,  it  is  true,  this  Strait,  of  which  fo 
much  has  been  faid,  has  become  narrower  5  but  at  the  fame  time  we  know,  that  long 
before  this  event  Charybdis  was  fituated  where  it  is  at  prefent.  The  ancient  and  un- 
interrupted tradition  of  the  MelTmefe  fefpefting  this  fail  is  confirmed  by  the  authority  of 
the  moft  celebrated  Italian,  Latin,  and  Greek  writers.  Fazello  tells  us,  "  Charybdis  ex 
parte  Sicilise  paulo  fupra  Meflanam."  "  Charybdis  is  fituated  on  the  fide  of  Sicily,  a  little 
beyond  Meffina." — Ovid  fays, 

"  Hinc  ego  dum  muter,  vel  me  Zanclasa  Charybdis 
"  Devorct !'' 

"  Let  dire  Charybdis  in  Zanclsean  feas, 
"  Devour  me  if  I  change  !" 

And  it  is   well  known  that  Zancle  was  the  ancient  name  of  Meffana,  now  Me/Tina. 
Tzetzes  in  Lycophron  fays,  "H  Xajvf 3ij  mpi  Mmni^  in.    *'  Charybdis  is  fituated  near  Mef- 
fina." 


Bcylla  and  Charybdis.  -  J I 

fina."  Strato  likewife,  after  having  mentioned  Mefllna,  proceeds,  AetKvurat  km  Xafi/fSij, 
/Aiicpov  'srpo  rrii  -sroAfaf,  iv  ra  tfop^/xa.  *'  Charybdis  is  feen  in  the  flrait  a  little  before  we  reach 
the  city."     Several  other  writers  nmight  be  cited  to  the  fame  purpofe. 

From  all  thefe  reafons  and  hiftorical  teftimonies  we  mufl  then  conclude  that  Homer  was 
not  exadl  with  refpe£l  to  tlie  fituation  of  Charybdis ;  nor  can  it  be  a  great  offence  to  fay, 
that  in  this  paflage  of  his  long  poem  he  has  certainly  nodded.  The  accuracy  of  feveral  of 
his  defcriptions  of  various  places  in  Sicily  cannot  be  denied.  It  is  fuch  that  we  muft  ei- 
ther fuppofe  that  he  had  himfelf  travelled  in  thofe  parts,  as  is  the  opinion  of  many  ;  or  at 
leafl:  that  he  had  procured  very  faithful  and  circumftantial  information  from  others.  Of 
this  the  rocks  of  Scylla  are  anexample.  But,  as  to  the  fuppofed  whirlpool  of  Charybdis, 
and  its  fituation,  I  think  we  may  venture  to  affirm  he  never  faw  it  himfelf,  and  that  the 
accounts  he  had  received  of  it  led  him  into  error. 

We  will  now  enquire  what  foundation  there  is  for  the  faying,  which  became  pro- 
verbial, that  "  he  who  endeavours  to  avoid  Charybdis  daflies  upon  Scylla  ;"  and  which 
was  applied  by  the  ancients  to  thofe  who,  while  they  fought  to  Ihun  one  evil,  fell  into  a 
worfe. 

On  this  fubje£l  I  likewife  made  enquiries  of  the  Meffinefe  pilots  abovementloned,  and  to 
what  better  mailers  could  I  apply  for  the  elucidation  of  fuch  a  proverb  ?  'Ihey  told  me  that 
this  misfortune,  though  not  always,  yet  frequently  happens,  unlefs  proper  meafures  are 
taken  in  time  to  prevent  it.  If  a  fhip  be  extricated  from  the  fury  of  Charybdis,  and  car- 
ried by  a  ftrong  foutherly  wind  along  the  (trait  towards  the  northern  entrance,  it  will  pafs 
out  fafely  ;  but  fhould  it  meet  with  a  wind  in  a  nearly  oppofite  diredlion,  it  would  become 
the  fport  of  both  thefe  winds,,  and,  unable  to  advance  or  recede,  be  driven  in  a  middle 
courfe  between  their  two  diredtions,  that  is  to  fay,  full  upon  the  rock  of  Scylla,  if  it  be 
not  immediately  aflifted  by  the  pilots.  They  added,  that  in  thefe  hurricanes  a  land  wind 
frequently  rifes,  which  defcends  from  a  narrow  pafs  in  Calabria,  and  increafes  the  force 
with  which  the  fhip  is  impelled  towards  the  rock. 

Before  I  began  to  write  on  Scylla  and  Charybdis,  I  perufed  the  greater  part  of  the  an- 
cient authors  who  have  written  on  the  fubjett.  I  obferve  that  they  almoft  all  reprefent 
thefe  dlfaftrous  places  in  the  mofl  gloomy  and  terrifying  colours,  as  continually  the  fcene 
of  tempefts  and  fhipwrecks.  Thefe  terrors  and  this  defl;ru£lion,  however,  they  are  far  from 
exhibiting  in  the  prefent  times,  it  rarely  happening  that  any  Hiips  are  loft  in  this  channel, 
either  becaufe  their  pilots  poflefs  the  knowledge  requifite  for  their  prefervation,  or  becaufe 
they  apply  for  the  neceflary  afliftance.  Whence  then  arifes  this  great  difference  between  an- 
cient times  and  the  prefent  ?  Can  we  fuppofe  that  Scylla  and  Charybdis  have  changed  their 
nature,  and  become  lefs  dangerous  ?  With  refpeft  to  the  former,' we  have  feen  that  this  hy- 
pothecs is  contradided  by  fadl ;  Scylla  ftill  remaining  fuch  as  it  was  in  the  time  of  Homer : 
and  with  regard  to  the  latter,  from  the  Strait  of  Meffina  becoming  narrower,  Charybdis 
muft  be  at  prefent  more  to  be  feared  than  formerly,  as  it  is  well  known  that  an  arm,  chan- 
nel, or  ftrait  of  the  fea  is  the  more  dangerous  in  proportion  as  it  is  narrow.  I  am  rather  of 
opinion  that  this  difference  arifes  from  the  improvement  of  the  art  of  navigation,  which 
formerly,  in  its  infancy,  dared  not  launch  into  the  open  fea,  but  only  creep  along  the  ftiore, 
as  if  holding  it  with  its  hand. 

Alter 


aa  'Cau/e  why  the  DaHgiff  of  Scylla  and  Chatyba'is  are  dlmwijhed. 

Alter  remus  aquas,  alter  tibi  radat  arenas,    , 
Tutus  eris  ;  medio  maxima  turba  marl. 

Propert.  Lib.  Ill- 

To  fliun  the  dangers  of  the  ocean,  fweep 
The  fands  with  one  oar,  and  with  one  the  deep. 

3But  time,  ftudy,  and  experience  have  rendered  her  more  mature,  better  informed,  and  more 
courageous »  fo  that  flie  can  now  pafs  the  wideft  feas,  brave  the  moft  violent  tempefts,  and 
laugh  at  the  fears  of  her  childhood. 

To  exemplify  and  fupport  the  probability  of  this  opinion,  it  will  not  be  neceflary  to  recur 
to  the  early  and  rude  ages ;  much  more  modern  times  will  furnilh  us  with  fufficient  proofs. 
That  part  of  the  Adriatic,  which  feparates  Venice  from  Rovigno  in  Iftria,  is  certainly  not 
the  moft  propitious  fea  to  navigators.  The  danger  of  being  hurried  in  fix  hours  from  one 
ihore  to  the  other,  and  there  ftranded ;  the  frequency  of  violent  winds  which  prevail  there  ; 
the  /hallows  and  fand-banks  which  break  tlie  waves  and  render  them  wild  and  irregular, 
may  certainly  caufe  fome  ferious  refledtion  in  thofe  who  embark  to  make  the  pafliige.  So 
■lately  as  the  laft  century,  the  fhipwrecks  in  this  fea  were  fo  numerous,  and  had  fo  terrified 
the  people  of  Rovigno,  that,  when  any  one  was  obliged  by  urgent  bufinefs  or  any  other 
caufe  to  go  to  Venice,  he  confidered  himfelf  as  more  likely  to  die  than  live  ;  and,  if  he  was 
the  father  of  a  family,  ufed  to  make  his  will  before  he  embarked.  The  Advocate  Conftan- 
tini,  a  native  of  that  country,  and  a  man  of  learning  and  ingenuity,  tokl  me  when  I  was 
-there,  that  he  had  read  more  than  one  of  thefe  teftaments,  depofited  among  the  public  ar- 
chives. 

But  at  prefent  I  will  not  fay  it  is  a  diverfion  or  pleafure  to  make  this  paflage,  fince,  a$ 
ftorms  are  not  unfrequent,  it  is  neceflary  to  be  cautious ;  but  ferious  accidents  rarely  hap- 
pen. I  have  myfelf  three  times  made  it  without  meeting  with  any  caufe  of  alarm.  To 
what  can  this  difference  be  attributed,  but  to  the  improvement  of  the  nautical  art  ?  Be- 
iides  that  the  mariners  of  Rovigno  were  not  then  fo  expert  in  the  management  of  their 
veflels  as  at  prefent ;  they  made  ufe  of  certain  barks  of  fo  improper  a  conftrudion,  as  I 
was  aflured  by  the  abovementioned  Conftantini,  that  it  was  impoffible  they  fiiould  long 
refift  the  violence  of  the  fea.  Thofe  on  the  contrary  that  have  been  built  fince  that  time, 
being  of  a  broad  and  flat  figure  and  very  folid,  are  capable  of  withftanding  the  moft  furi- 
ous ftorms.  They  are  there  called  Ircicere,  and  are  in  great  reputation  in  all  the  neigh- 
bouring countries.  We  here  find  a  part  of  the  fea  in  which  veflels  were  formerly  fo 
frequently  wrecked,  and  which  could  not  be  traverfed  but  at  the  rifle  of  life,  now  deprived 
of  all  its  terrors,  and  rendered  eafily  paflable,  merely  by  the  improvements  made  in  the  art 
of  navigation. 

As  a  farther  and  ftill  more  convincing  proof  that  the  dangers  of  Charybdis  and  Scylla, 
though  in  themfelves  the  fame  that  they  anciently  were,  have  been  diminifhed,  and  the 
dread  they  infpired  removed  by  the  rapid  advances  to  perfe£lion  which  this  art  has  made 
in  madern  times  ;  1  fliall  adduce  an  example  in  another  fea  no  lefs  an  objedl  of  ter- 
ror from  tempefts  and  ftiipwrecks,  I  mean  tfic  Cape  of  Good  Hope,  called  the  Stormy 
Cape  by  the  firft  difcoverer,  and,  by  the  mariners  of  thofe  times,  the  Raging  Lion.  How 
dreadful  were  the  dangers  of  this  place,  where  the  two  oceans  defcending  down  the  oppo- 

fitc 


tcylla  and  Charyhdis.— Refining  of  Nitre,  25* 

ffte  fides  of  Africa  met  and  cialhed  together;  where  contending  winds,  whofe  power  was 
greater  in  the  boundlefs  ocean  ;  where  mountainous  waves,  rocks,  and  whirlpools  threat- 
ened inevitable  deftruftion  !  What  preparations,  what  caution  were  thought  neceflary  for 
the  {hip  whicli  was  to  make  this  dangerous  paflage  ?  Able  pilots  who  had  frequently  mada 
the  voyage ;  marts  and  yards  fecured  by  additional  ropes  ;  a  large  fupply  of  falls  and  cables,, 
thicker  and  ftronger  than  ufual ;  and  a  double  rudder,  that  in  cafe  one  fhould  be  damaged; 
tliere  might  be  another  to  aft.  The  mariners  wer«  to  be  fadened  to  their  pofts  by  ftrong 
ropes ;  the  paffengers  (hut  down  below,  and  the  deck  left  clear  for  the  crew  ;  a  number  of 
whom  ftood  with  hatchets  in  their  hands,  ready  to  cut  away  the  mafts  fliould  it  be  neceflary. 
The  guns  were  flowed  in  the  hold  as  ballaft,  and  the  port-holes,  windows,  and  every  kind' 
of  aperture,  carefully  clofed.  Such  were  the  precautions  taken  in  the  laft  century,  on' 
doubling  the  Cape  of  Good  Hope  ;  but  how  few  of  them  are  now  neceflary  to  perform  this 
voyage  in  perfedl  fafety !  Of  this  I  have  had  the  fatisfaftion  to  be  certified  by  an- 
Englifh  gentleman,  Mr.  Macpherfon,  with  whom  I  had  the  pleafure  of  converfihg  in 
Pavia,  in  July  179:0;  and  who  had  twice  doubled  this  Cape  in  his  voyages  to  India  ;  a-. 
gentleman  of  great  refpe£i:ability  for  his  information,  for  the  various  long  voyages  he  has 
made,  and  the  honourable  employments  he  has  held. 

The  facility  with  which  this  paflage  may  now  be  made,  is  therefore  the  confequence  bf 
the  perfedion  to  which  the  art  of  navigation  has  arrived;  and  the  fame  we  may  conclude 
with  refpe£l  to  Charybdis  and  Scylla,  whicli  at  prefent  have  nothing  terrible  but  the  name, , 
to  thofe  who  pafs  them  with  the  requifite  precautions. 


V. 

hflruBions  for  refining  Saltpetre  by  a  new  Procefs.  By  J.  A.  CSAPTALy  J.  P.  ChaMPT  and: 

Bon  JOUR  *. 

X  HE  crude  faltpetre  is  to  be  beaten  fmall  with  mallets,  in  order  that  the  water  may  more 
eaGly  attack  every  part  of  the  mafs.  The  faltpetre  is  then  to  be  put  into  tubs,  five  or  fix- 
'  hundred  pounds  in  each  tub.  Twenty  per  cent,  of  water  is  to  be  poured  into  each 
tub,  and  the  mixture  well  ftirred.  It  muft  be  left  t& macerate,  or  digeft,  until  the  fpecific. 
gravity  of  the  fluid  ceafes  to  augment.  Six  or  feven  hours  are  fufficient  for  this  firft  ope-- 
sation,  and  the  water  acquires  the  denfity  of  between  25  and  35  degrees.  (Sp.  Gr.  1.21, 
and  1.306.     See  Philof.  Journal  I.  39.) 

The  firfl;  water  muft  then  be  poured  ofi^,  and  a  fecond  portion  of  water  muft  be  poured 
on  the  fame  faltpetre  amounting  to  10  per  cent. ;  after  which  the  mixture  muft  be  ftirred 
up,  fuffered  to  macerate  for  one  hour,  and  the  fluid  drawn  or  poured  ofi^. 

Five  per  cenj,  of  water  muft  then  be  poured  on  the  faltpetre ;  and  after  ftirring  the  whole, 
the  fluid  muft  be  Immediately  drawn  off. 

When  the  water  is  drained  from  the  faltpetre,  the  fait  muft  be  thrown  into  a  boiler  con- 
taining 50  percent,  of  boiling  water.  When  the  folution  is  made,  it  will  mark  between  66 
and  68  degrees  of  the  hydrometer.  (Sp.  Gr.  1.848,  and  1.898.) 

*  Tranflated  from  the  Journal  de  Phyfique,  bearing  date  Auguft  1794)  but  lately  publilhed. 

The 


t4  Rffiiitng  of  Nitre  iy  Percolation,  Soluiiun,  feV. 

The  folution  is  to  be  poured  into  a  proper  veflel,  where  it  depofits  by  cooling  about  two- 
thirds  of  the  faltpetre  originally  taken.  The  precipitation  begins  in  about  half  an  hour, 
and  terminates  in  between  four  and  fix  hours.  But  as  it  is  of  importance  to  obtain  the 
faltpetre  in  fmall  needles,  becaufe  in  this  form  it  is  msre  eafily  dried,  it  is  neceflary  to  agi- 
tate the  fluid  during  the  whole  lime  of  the  cryftallization.  A  flight  motion  is  communi- 
cated to  this  liquid  mafs  by  a  kind  of  rake,  in  confequence  of  which  the  cryftals  are  de- 
pofited  in  very  flender  needles. 

In  proportion  as  the  cryftals  fall  down,  they  are  fcraped  to  the  borders  of  the  veflel, 
whence  they  are  taken  with  a  flcimmer,  and  thrown  to  drain  in  baskets  placed  on  trefiels, 
in  fuch  a  manner  that  the  water  which  paflcs  through  may  either  fall  into  the  cryfliallizing 
vefl^el,  or  be  received  in  bafons  placed  underneath.  * 

The  faltpetre  is  afterwards  put  into  wooden  vefl'els  in  the  form  of  a  mill-hopper  or  in- 
verted pyramid  with  a  double  bottom.  The  upper  bottom  is  placed  two  inches  above  the 
lower  on  wooden  ledges,  and  has  many  fmall  perforations  through  which  water  may  pafs 
to  the  lower  bottom,  which  likewife  afibrds  a  paflage  by  one  fingle  aperture.  A  refervoir 
is  placed  beneath.  The  cryftallized  faltpetre  is  walhed  in  thefe  veflels  with  5  per  cent,  of 
water ;  which  water  is  afterwards  employed  in  the  folution  of  faltpetre  in  fubfequent  ope- 
rations. 

The  faltpetre,  after  fuflicient  draining,  and  being  dried  by  expofure  to  the  air  upon 
tables  for  feveral  hours,  may  then  be  employed  in  the  manufacture  of  gunpowder. 

But  when  it  is  required  to  ufe  the  faltpetre  in  the  fpeedy  and  immediate  manufaiflure  of 
gunpowder,  it  mud  be  dried  much  more  ftrongly.  This  may  be  efl^eded  in  a  (love,  or 
more  fimply  by  heating  it  in  a  flat  metallic  veflTel.  For  this  purpofe  the  faltpetre  is  to  be 
put  into  the  Teflel  to  the  depth  of  five  or  fix  inches,  and  heated  to  40  or  50  degrees  of  the 
thermometer  (or  about  135  of  Fahrenheit).  The  faltpetre  is  to  be  flirred  for  two  or  three 
hours,  and  dried  fo  much  that,  when  ftrongly  prefled  in  the  hand,  it  fliall  acquire  no  confif- 
tence,  nor  adhere  together,  but  refemble  a  very  fine  dry  fand.  This  degree  of  drynefs 
is  not  required  when  the  powder  is  made  by  pounding. 

From  ^hefe  circumflances  we  find,  that  two  faline  liquids  remain  after  the  operation, 
(1)  the  water  from  the  wafliing  ;   and  (2)  that  from  the  cryftallizing  veflels. 

We  have  already  remarked,  that  the  wafliing  of  the  faltpetre  is  performed  in  three  fuc- 
ceflivc  operations,  in  which,  upon  the  whole,  the  quantity  of  fluid  made  ufe  of  amounts 
t6  ;^5  per  cent,  of  the  weight  of  the  crude  faltpetre.  Thefe  wafliings  are  eftabliflied  on 
the  principle,  that  col3  water  diflblves  the  muriates  of  foda,  and  the  earthy  nitrates  and 
muriates,  together  with  the  colouring  principle,  but  fcarcely  attacks  the  nitrate  of  potafli. 

The  water  of  thefe  three  wafhings  therefore  contains  the  muriate  of  foda,  the  earthy 
falts,  the  colouring  principle,  and  a  fmall  quantity  of  nitrate  of  potafli,  the  amount  of  which 
is  in  proportion  to  that  of  the  muriate  of  foda,  which  determines  its  folution. 

The  water  of  the  cryllallizing  veflels  contains  a  portion  of  the  muriates  of  foda,  and  of 
the  earthy  falts  which  efcaped  the  operation  of  wafliing,  and  a  quantity  of  nitrate  of 
potafli,  which  is  more  confiderable  than  that  of  the  former  folution. 

The  waters  made  ufe  of  at  the  end  of  the  operation,  to  whiten  and  wafli  the  cryftals 
depofited  in  the  pyramidal  veflel,  contain  nothing  but  a  fmall  quantity  of  nitrate  of  potafli. 

Thefe 


EJlmate  of  Utenfils  and  Men  for  the  Work  of  vefiniiig  Saltp:tre,  '  25 

Thefc  waters  are  therefore  very  drfferent  in  their  nature.  The  water  of  the  wafliings  i« 
really  a  mother  water.  It  muft  be  collected  in  veflcls,  and  treated  with  potafh  by  the 
known  procefles.  It  mud  be  evaporated  to  66  degrees  (or  1,848  fp.  gr.),  taking  out  the 
jnuriate  of  foda  as  it  falls.  This  folution  is  to  be  faturated  with  2  or  3  per  cent,  of  potaQi, 
then  fuffered  to  fettle,  decanted  and  poured  into  cryfiallizing  veffels,  where  20  per  cent, 
of  water  is  to  be  added  to  keep  the  whole  of  the  muriate  of  foda  fufpended. 

The  waters  which  are  thus  obtained  by  treatment  of  the  mother  water,  niay  be  mixed 
■with  the  water  of  the  firft  cryftallization.  From  thefc  the  marine  fait  may  be  feparated 
by  fimplc  evaporation  ;  and  the  nitrate  of  potafli,  which  they  hold  in  folution,  may  be 
:aftcrwards  obtained  bv  cooling. 

The  fmall  quantity  of  water  made  ufe  of  to  wafli  and  whiten  the  refined  faltpetre,  con- 
tains nothing  but  the  nitrate  of  potafli :  it  may  therefore  be  ufed  in  the  folution  of  the 
faltpetre  when  taken  from  the  tubs. 

From  this  defcription  it  follows,  that  a  manufadtory  for  the  fpeedy  refining  of  faltpetre 
ought  to  be  provided  with  (i)  mallets  or  rammers  for  pounding  the  faltpetre,  (2)  tubs  for 
wafliing,  {3)  a  boiler  for  folution,  (4)  a  cryftall'zing  veflel  of  copper  or  lead,  in  which 
the  faltpetre  is  to  be  obtained  by  cooling,  (5)  balkets  to  drain  the  cryftals,  (6)  a  wooden 
cafe  or  hopper  for  the  laft  wafliing  and  draining  the  faltpetre,  (7)  fcales  and  weights  for 
weighing,  (8)  hydrometers  and  thermometers  to  afcertaiii  denfities  and  temperatures, 
(9)  rakes  to  agitate  the  liquor  in  the  cryftallizing  veflel,  (10)  flcimmers  to  take  out  the 
cryft:als  and  convey  them  to  the  baflcets,  ( 1 1 )  fyphons  or  hand-pumps  to  empty  the  boilers. 

The  number  and  dimenfions  of  tRefe  fevcral  articles  mufl:  vary  according  to  the  quantity 
of  faltpetre  intended  to  be  refined. 

If  it  be  propofed  to  refine  ten  thoufand  weight  of  crude  faltpetre  per  day,  the  requifite 
men  and  utenfils  may  be  determined  as  follows : 

Part  of  the  ground  near  the  magazine  may  be  difpofed  for  conveniently  breaking  and 
pounding  the  faltpetre. 

This  ground-fiiould  be  paved  with  large  flat  fl;ones  very  uniformly,  or  with  thick  pieces 
of  wood.  Mallets  fimilar  to  thofe  ufed  in  pulverizing  gypfum  may  be  applied  to  this  ufe. 
Two  men  are  fufiicient  to  weigh   and  pound  the  faltpetre,  and  flow  it  in  the  magazine. 

As  the  three  wafhings  require  two  days,  and  each  tub  can  hold  only  five  or  fix  hundred 
pounds  of  faltpetre,  it  would  require  twenty  days  to  refine  ten  thoufand  weight  (with  one  tub). 

Thefe  tubs  are  two  feet  and  a  half  in  height,  and  the  fame  in  diameter.  They  muft  be 
very  well  made,  in  order  that  the  water  of  the  wafliing  may  not  leak  out.  ^  They  are  to  be 
placed  folidly  on  a  plane  flightly  inclined,  of  fuch  a  material  as  fliall  not  imbibe  the  water 
which  may  be  fpilt  during  the  operation,  but  tranfmit  it  to  a  refervoir  placed  at  the 
extremity  of  the  row  of  tubs,  ■  - 

Twenty  of  thefe  tubs  mufl:  be  difpofed  in  two  parallel  lines  ;  the  planes  on  which  they 
arefet  may  incline  towards  each  other,  and  form,  by  their  union,  the  gutter  or  cavtty  for 
tranfmittlng  into  the  common  refervoir  fuch  waters  as  may  efcape.  Thefe  tubs  are  per- 
forated at  the  diftance  of  two  inches  from  the  bottom.    1  he  aperture  is  clofed  by  a  fpigot* 

Four  men  may  be  appropriated  to   the  wafhing  of  the  faltpetre.     It  is  a  part  of  their 

duty  to  convey  the"  faltpetre  from  the  magazine,  to  the  tubs,  and  from  the  tubs-lo  the  boiler. 

Vol.  II.— Afril  1798.  E  J 


26  Spfeity  Procefsfor  refining  Saltpetre. 

'    'ft  is  fcarccly  necefTary  to  obferve  that  the  tubs  muft  ftand  fufRciently  apart,  and  be  fo 
difpofed  that  the  work  may  be  eafy  and  convenient. 

A  boiler  of  a  conical  form,  five  feet  wide  and  four  deep,  will  ferve  for  three  operatiorts 
■per  day,  and  confequently  to  refine  fifteen  thoufand  weight.  A  Cngle  man  is  fufHcient  to 
attend  the  boiler. 

The  veflel  for  cryftallization  is  of  lead  or  copper,  and  muft  be  as  near  the  boiler  as  poflible. 
Its  depth  is  fifteen  inches,  its  length  ten  feet,  and  its  width  eight.  It  muft  be  placed  on 
a  very  folid  fupport,  fo  that  its  bottom  may  every  where  reft  upon  it.  It  is  convenient  to 
raife  this  fupport  of  mafonry  about  twelve  inches  above-  the  ground.  By  this  means  the 
borders  of  the  cryftallizing  veflel  will  be  27  inches  above  the  floor,  which  will  render  the 
operation  eafy  and  convenient. 

It  has  appeared  to  us  of  advantage  to  give  to  the  bottom  of  the  cryftallizing  yeflel,  an 
inclination  of  four  inches  from  the  fides  to  the  middle,  merely  in  the  longitudinal  direc- 
tion. The  folutions  may  be  emptied  for  feveral  fuccefiive  times  from  the  boilers  into  the 
cryftallizing  veflTel,  after  having  taken  out  the  cryftals  depofited  from  each  folutibn. 

Four  men  appear  neccflary  for  the  operation  of  the  cryftallizing  veflel.  Their  bufinefs 
is  to  agitate  the  fluid  continually  with  the  rakes.  They  colledl  without  intermiflion  on 
the  borders  of  the  veffel  the  cryftals  which  fall  down,  and  convey  them  with  a  Ikimiricr  to 
the  bafliets  prepared  for  their  reception  and  draining.  Thefe  fame  workmen  put  the  falt- 
petre  into  the  wooden  veflTel  for  the  laft  wafliing  and  drainage,  and  carry  the  refined  falt- 
petre  into  the  magazine.  < 

For  want  of  a  large  cooler  for  cryftallization  a  fhallow  boiler  may  be  ufed,  or  the  faQie 
veflels  which  ferve  for  cryftallization  in  the  prefent  works  for  refining  this  fait. 

To  prepare  the  faltpetre  for  the  manufaclure  of  gunpowder,  it  may  be  dried,  after  re» 
fining,  by  two  procefl"es,  (i)  by  expofing  it  to  the  open  air,  or  the  fun,  for  feveral  hours, 
upon  tatles  ;  or  (2)  by  expofing  it  in  a  fhallow  metallic  veflel  for  two  hours,  to  the  heat  of 
40  or  50  degrees  (about  135  Fahrenheit).  In  either  cafe  it  muft  be  agitated  and  ftirred, 
witli'fcarcely  any  interruption,  in  order  to  dry  it  fpeedily  and  equally. 


Confiderable  experience  has  fhewn  us,  that  the  procefs  here  defcrlbed  is  the  moft  fimple 
and  economical.  But,  to  prevent  others  from  trying  fuch  methods  as  might  feem  ptomifing, 
though  we  have  thought  fit  to  rejeft  them,  it  will  be  proper  to  ofix:r  the  following  remarks : 

1.  Trial  has  been  made  to  diflTolve  the  faltpetre,  cryftallize  it,  and  then  wafti  it  to  fcpa- 
rate,the  fea-falt. 

This  procefs  appears  moft  advantageous  at  firft  fight,  becaufe  it  faves  the  pounding ;  but 
It  has  great  inconveniences,  i.  Crude  faltpetre  diflblved  in  50  per  cent,  of  water,  and 
poured  into  the  veflel  for  cryftallization,  does  not  depofit  the  fame  quantity  of  faltpetre 
as  it  would  do  if  ivafhed  before  the  folution.  This  difference  depend?  on  the  muriate  of 
foda  in  the  crude  faltpetre,  which  facilitates  the  folution  of  the  nitrate  of  potafli,  and  con- 
fequently the  water  of  the  cryftallizing  veflels  muft  retain  in  folution  more  nitrate  of  pot- 
afli, when  the  crude  faltpetre  is  diflblved,  than  when  it  has  been  previoufly  waflied  with 

cold 


.  Examination  of  various  Prociffes. .'  J7 

•o^d  water,  miH.  deprived  of  the  marir^e  fait  V(rhich  \x.  contains. .  .2.  The  waOiing^  of  falt- 
petre,  when  it  is  performed  after  tlie'feiuHon  and  cryftaliizatioH^requires  40  of'soper  ccitit! 
of  water  inftead  of  35.  '' '' " 

3.  Trial  has  been  made  to  diffolye  faltpetre  in  20  or  25  per  cent,  of  boiling  water;  to 
take  out  the  fea-falt  in  proportion  as  it  falls  by  the  ebullition  of  the  liquor  j  to  dilute  the 
fluid  with  30  per  cent,  of  additional  water,  and  then  to  convey  it  into  the  veflel  of  cryftal- 
lization.  It  was  expedted  that  the  wafliings  with  cold  water  might  be  avoided,  or  confi- 
derably  diminiftied  by  thefe  means  5  but,  not  to  mention  that  ebullition  maintained  for  four 
or  five  hours  to  feparatc  the  fea-falt  fuppofes  very  great  confumption  of  time,  fuel,  and  falt- 
petre, the  wafliings  are  flill  indifperifable  to  remove  the  colouring  principle,  and  to  carry 
off  the  laft  portions  of  muriate  of  foda. 

4.  It  may  be  thought  that  the  quantity  of  waiter  in  the  wafliings  might  probably  be  di- 
miniflied  ;  but  there  is  reafon  to  fear  that  when  the  faltpetre  is  loaded  with  fea-falt,  it 
cannot  be  perfectly  refined  by  the  ufc  of  a  lefs  quantity  of  water  than  we  have  prefcribed. 

5.  The  operator  may  alfo  be  tempted  to  diminifli  the  proportion  of  water  employed  in 
the  folution;  but  we  are  convinced  by  numerous  experiments,  that  this  proportion  is  the 
mofl;  fuitable.  If  it  be  increafed,  the  faltpetre  remains  diflblved  in  the  fluid ;  if  it  be  dimi- 
niflied,  it  fettles  or  falls  down  in  a  folid  mafs.  Obfervation  has  proved,  that  the  degree  of 
faturation  bed  adapted  to  this  work,  is  between  the  66th  and  68th  degrees  of  the  hydro- 
meter (fp.  gr.  1.848,  and  i.8d>6.)  1  ' 

6.  It  may  likewife  be  thought  more  Ample  and  economical  to  treat  the  folution  of  crude 
faltpetre  with  potafli.  But  it  is  to  be  feared  in  this  cafe  that  part  of  the  alkali  might  be  em- 
ployed in  decompofing  the  muriate  of  foda,  to  convert  it  into  muriate  of  potafli ;  and  it  mull 
be  obferved,  that  this  laft  fait  is  not  at  all  proper  to  decompofe  the  earthy  nitrates,  notwith- 
ftanding  the  aflertions  of  flcilful  chemifts  to  that  effeft. 

It  appears,  therefore,  more  convenient  to  defer  the  treatment  of  the  mother  waters,  and 
not  to  ufe  potafli  till  after  the  fea-falt  has  been  feparated  by  evaporation.       .  '  : 
This  procefs,  therefore,  unites  a  number  of  advantages. 

1.  Itconfumes  much  lefs  fuel :  for,  inftead  of  two  long  folutionsand  ebullitions,  nothing 
more  is  fequired  than  to  give  the  water  a  boiling  heat  in  order  to  dilTolve  the  faltpetre. 

2.  It  requires  lefs  time.  Three  days  are  fuflicient  to  purify  the  faltpetre  to  the  degree 
fuitable  for  making  gunpowder. 

3.  It  difpofes  the  faltpetre  to  dry  more  readily.  As  the  cryftals  are  no  larger  than  fTnall 
needles,  a  few  hours' expofure  to  the  air  are  fufEcient  for  its  complete  deficcation.  This 
advantage  is  inefl;imable,  particularly  in  a  feafon  wherein  feveral  months  would  be  required 
to  drain  the  large  loaves  of  nitre  ;  and  in  which,  confequently,  the  fabrication  of  gunpowder 
would  be  either  retarded  or  fufpended,  and  the  drying-houfes  encumbered  with  quantities 
of  humid  nitre.  '  ~ 

4.  It  requires  lefs  fpace.  A  boiler  five  feet  in  diameter  and  four  in  depth,  a  veflel  for 
cryftallization  of  a  few  feet  dimenfions,  and  thirty  tubs,  are  perfedly  fufficient  to  refine  fif- 
teen thoufand  weight  daily.  " 

5.  It  occafions  lefs  lofs.  Very  accurate  experiments  have  fliown  that  the  folutions  ufed 
in  the  ancient  procefs  occafioned  a  lofs  of  faltpetre,  by  mere  evaporation,  which  amounted 
to  7  per  cent,  of  the  original  quantity.     By  this  new  procefs,  the  water  which  holds  the  falt- 

E  2  ^     petre 


aS  Luminous  Borax.— New  Air  Pump. 

petre  in  folution  Is  never  heated  to  boiling,  the  fait  does  not  remain  In  the  boiler,  and  the- 
evaporation  is  almofl:  nothing. 


Vt. 

On  the  Light  emitted  by  Super/aturated  Borate  of  Soda,  or  Common  Borax.    By- Air,  F.  ACCUM, 

To  Mr.  Nicholson^ 
SIR, 

JL  HAT  two  flints  and  fevcral  other  filiceous  flones,  ftruck  againft  each  other,  appearJu— 
minous  on  the  fide  ftruck  upon  ;  and  that  phofphate  of  lime,  tremollte,  fugar,  gum  elemii . 
black  jack,  and  various  refins-become  luminous,  and  emit  phofphoric  fparJcs  in  the  dark, 
when  fcratched  with  a  (harp  inftrument,  or  ftruck  againft  one  another,  are  well  known 
to  every  tyro  of  natural  philofophy  ;  but  th'nt  fuperfaturated  borate  offoda  poffefies  this  pro*- 
perty  in  the  higheft  degree,  has  not  perhaps  been  hitherto  remarked.     Two  pieces  of  this 
fait,   of   confiderable  magnitude,  ftruck  againft  anotljer,.  or  a  fwift  blow  with  any  fliarp  in- 
ftrument upon  it,  produces  fuch  a  flafti  of  white  light,  as  none  of  the  before-mentioned 
fubftances  are  capable  of  giving.     It  deferves  therefore  a  place  under  the  ciafs  of  thofe 
kinds  of  phofphoric  fubftances  which  give  a  perceptible  light  by  attrition  or  percuflion, 
without  having  been  expofed  either  to  the  folar  or  artificial  light ;  for  which  reafon  I  take 
the  liberty  of  laying  this  before  you,    begging  you  will  give  thefe   lines   a  place  ia  your- 
much-admired  Journal  of  Natural  Philofophy . 

I  remain.  Sir,  your  very  humble  fervant, 

FREDERICK  ACCyM. 
Hay- Market,  No.  17. 


VII. 

Neiu  ConJlruElion  of  the  Air  Pump.     By  Sir  G£ORGE  S.  Mackenzie,  Bart. 

Jr  IG.  I.  plate  I,  reprefents  a  fcdion  of  the  barrel.  C  is  a  cup  for  oil  to  moiften  the  collar 
of  leathers  L,  in  which  the  pifton  rod  R  works.  ?i  is  a  plug— P  P  P  P  is  the  pifton,  which  is 
folid,  except  a  fpace  for  a  collar  of  leathers  ^,  through  which  the  wire  W  attached  to  the 
valve  V,  pafles  into  a  perforation  in  the  pifton  rod.  N  is  a  fmall  nut  to  prevent  the  valve 
from  rifing  too  high.  This  method  of  lifting  the  valve  was  invented  many  years  ago  by 
Dr.  Rutherford  of  "Edinburgh.  X  is  a  perforation  in  the  fide  of  the  bottom  of  the  barrel, 
into  which  is  inferted  a  piece  of  metal,  as  in  fig.  5,  with  a  filk  valve  tied  over  it,  opening 
downwards  into  the  pipe  K.   E  is  the  pipe  leading  to  the  receiver. 

The  conftrudion  of  the  bottom  of  the  barrel  is  feen  in  fig.  2  and  3.  Fig.  4  is  the 
valve  and  wire.  Fig.  5  ftiews  the  conftrudlion  of  the  pipe  E  leading  to  the  receiver,  which 
is  better  than  bent.copper.tubcs,  as  thefe  are  apt  to  crack.     Fig.  6  is  caft  folid  and  bored. 

Figt 


jiir  Pump. — Maximum  of  various  Air  Pumps.  29 

Fig.  7  is  the  cap  fcrcw  by  which  the  pipes  are  fixed.     Fig,  8  is  the  pipe  ufed  for  the 
condenfing  apparatus. 

That  this  pump  may  work  well,  it  is  neceffary  that  the  bottom  of  the  pifton  be  perfedly 
flulh  with  the  bottom  of  the  barrel. — The  method  of  operation  is  as  follows  : 

When  the  pifton  is  to  be  raifed,  let  the  plug  ^,  be  opened. — The  pifton  rifing,  expels 
the  air  above  it  through  (p.  When  the  pifton  is  at  the  higheft,  (hut  the  plug.  There  will 
now  be  no  preflure  above  the  pifton,  which  will  greatly  facilitate  the  working.  As  the 
pifton  rifes,  the  friction  of  the  collar  of  leathers  h  will  raife  the  valve  V,  and  the  air  in  the 
receiver  through  the  communication  E  will  expand  itfclf  into  the  barrel.  When  the  pifton  is 
deprefled,  V  ftiuts,  and  the  air  is  expelled  through  K,  to  which  a  pipe  as  fig.  8  may  be 
attached  for  condenlation.  When  the  pifton  reaches  the  bottom,  no  air  will  be  left  in  the 
barrel,  except  the  very  fmall  quantity  in  the  very  fmall  hole  of  the  valve  X,  which  is  very 
little  when  compared  to  the  capacity  of  the  barrel.  By  proceeding  in  this  manner,  a  very 
perfecl  vacuum  will  be  formed  in  the  receiver. — By  taking  oft'  the  receiver  and  applying  . 
the  pipe  fig.  8,  and  attaching  it  to  any  veffel,  and  opening  the  plug  ip,  we  have  a  com-- 
plete  condenfing  apparatus.  If  required,  the  air  may  be  takftn  from  the  receiver  and 
thrown  into  another  veffel.  Moiftened  leather  ought  not  to  be  ufed  for  fixing  the  re- 
ceiver, as  vapours  are  conftantly  iffuing  from  it  -,  a  drying  lute  is  better. 

This  air  pump  may  be  made  of  a  much  cheaper  conflju£llon  than  that  of  the  plate,,, 
which,  however,  is  the  more  convenient. 


In  the  obliging  letter  which  accompanied  this  communication,  the  author  aflures  me, 
that  its  fimplicity  and  convenience  have  been  found  confiderable  by  experience.  The 
reader  will  perceive,  by  turning  to  the  firft  volume  of  our  Journal,  p.  128,  that  the  happy 
contrivance  of  the  wire  for  lifting  the.  lower  valve  is  alfo  claimed  by  Cuthbertfon,  who 
in  his  pamphlet*,  page  6,  informs  us  that  tlie  hint  of  fuch  an  apparatus  was  firft  given 
to  him  by  M.  Pacts  van  Trooftwyk.  It  is  not  faid  that  Ur.  Rutherford  carried  his  in- 
vention into  prailice.  This  merit  is  due  to  Mr.  Cuthbertfon  and  Sir  G.  M.  I  remem- 
ber the  fame  ingenious  thought  having  been  alfo  ftated  by  another  philofophical  gentleman, 
in  1783,  when  the  air  pump  of  Haasf  was  much  talked  of. 

The  air  pump  of  Sir  George  Mackenzie  differs  in  effe£b  from  that  oPMr.  Cuthbertfon 
in  the  folidity  of  the  pifton,  and  in  not  having  an  oil  veffel  to  the  valve  through  wliich  the 
air  is  extruded.  The  air  pump  of  Sir  George  will  ceafe  to  exhauft,  fuppofing  every 
thing  elfe  perfeft,  when  the  mafs  of  air  in  the  receiver  bears  the  fame  proportion  to  an 
equal  volume  of  external  air,  as  the  capacity  of  the  bore  of  the  valve-piece  X,  bears  to  the 
interior  capacity  of  the  barrel  when  the  pifton  is  up.  Cuthbertfon's  pump  will  have  a 
fimilar  limit  with  relation  to  the  communication  pipe  as  to  the  upper  valve  (Philof  Jcur-- 
nal,  pi.  7,  vol.  I,  fig.  r.)  and  the  capacity  of  the  barrel  above  the  pifton  when  down.  In 
Prince's  air  pump,  and  in  the  projedt  mentioned  at  p.  131  of  the  fame  volume;  if  the 

*  Defcription  of  an  Improved  Air  Pump,  &c.  by  John  Cuthbertfon,  London  ;  fold  by  Johnfon.  No  date, 
l>ur,  as  I  tbink,  publifticd  feven  or  eight  years  ag9.  ' 


t  Pliil.  Tranf.  m,i;cc,lxxiii. 


Talv«s ! 


30  ABion  of  Nitre  vpm  Gold,  ^c. 

valves  be  made  to  open  mechanically,  the  maximum  pf  exhau^ion  v?ill  in  tlneory  be  in 
the  duplicate  ratio  of  the  fmaller  fpace  to  the  larger,  afluming  both  ftrokes  to  be  eqqal  in 
the  barrels  through  which  the  air  fuccefiivcly  pafles.  And  in  Sadler's  pump  with  oil 
(Ibid,  plate  xix.  fig.  i.)  the  maximum  will  be  indefinitely  great,  bccaufe  every  llrpkc  muft 
take  out  a  like  part  of  the  refidue  of  air  from  the  receiver. 


VIII. 

On  the  Aaion  of  Nitre  upon  Gold  and  Platina.    By  SmjtHSON  TenNANT,  Efq.'F.  R.  S.* 

vJOLD,  which  cannot  be  calcined  by  expofure  to  heat  and  air,  has  been  alfo  confidered  as 
incapable  of  being  afFefted  by  nitre.  But  in  the  courfe  of  fome  experiments  on  the  dia- 
mond, an  account  of  which  has  been  communicated  to  this  fociety,  I  obfcrved  that  when 
nitre  was  heated  in  a  tube  of  gold,  and  the  diamond  was  not  in  fufficient  quantity  to  fupply 
the  alkali  of  the  nitre  with  fixed  air,  a  part  of  the  gold  was  diflblved.  From  this  obier- 
vaiion  I  was  induced  to  examine  more  particularly"  the  a£lion  of  nitre  upon  gold,  as  well 
as  to  enquire  whether  it  would  produce  any  efFe£t  upon  filver  and  platina. 

"With  this  intention  I  put  fome  thin  pieces  of  gold  into  the  tube,  together  with  nitre,  and 
cspofed  them  to  a  ftrong  red  heat  for  two  or  three  hours.  After  the  ttib^  was  taken  from 
the  fire,  the  part  of  the  nitre  which  remained,  confifting  of  cauftic  alkali,  and  of  nitre  par- 
tially decompofed,  weighed  140  grains  ;  and  60  grains  of  the  gold  were  found  to  have  been 
diflblved.  Upon  the  addition  of  water,  about  50  grains  of  the  gold  were  precipitated  in  the 
form  of  a  black  powder.  The  gold  which  was  thus  precipitated  was  principally  in  its 
metallic  ftatp,  the  greater  portion  of  it  being  infolublc  in  marine  acid.  The  remaining 
gold,  about  ten  grains  in  weight,  communicated  to  the  alkaline  folution  in  which  it  was' 
retained,  a  light  yellow  colour.  By  dropping  into  this  folution  diluted  vitriolic  or  nitrous 
acid,  it  became  at  firftof  a  deeper  yellow,  but,  if  viewed  by  the  tranfmitted  light,  it  foon 
appeared  green,  and  afterwards  blue'.  The  alteration  of  the  colour  from  yellow  to  blue, 
arifes  from  the  gradual  precipitation  of  the  gold  in  its  metallic  form,  which  by  the  tranf- 
mitted light  is  of  a  blue  colour :  though  the  gold  is  precipitated  from  this  folution  in  its 
metallic  form,  yet  there  feems  to  be  no  doubt  that,  while  it  remains  diflblVed,  it  is  entirely 
in  the  ftate  of  calx.  Its  precipitation  in  the  metallic  flate  is  occafioned  by  the  nitre  con- 
tained in  the  folution,  which,  having  loft  part  of  its  oxygen  by  heat,  appears  to  be  capable 
of  attra£ting  it  from  the  calx  of  gold  ;  for  I  found,  that  if  the  calx  of  gold  is  diflblved  by 
being  boiled  in  cauftic  alkali, and  a  fuflScient  quantity  of  nitre,  which  has  loft  fome  of  its  air 
by  heat,  is  mixed  with  it,  the  gold  is  precipitated  by  an  acid  in  its  metallic  ftate  f . 

Having 

*  Pliilofophical  Tranfaftions,  M,DCC,xcvir. 

,f  As  the  precipitation  of  gold  in  its  metallic  form  by  nitre  which  has  loft  foitie  of  its  oxygen,  has  not,  I  be- 
lieve, been  noticed,  it  may  not  be  improper  to  mention  fome  ofthofe  fafts  relating  to  it  which  feem  moft  enti- 
tled to  attention.  Nitre,  which  has-been  heated  fome  time,  precipitates  gold  in  its  metallic  ftate  from  a  folution 
in  aqua  regia,  if  it  is  diluted  with  water.  If  a  folution  of  gold  in  nitrous  acid  is  dropped  into  pure  water,  the 
calx  of  gold  is  feparated,  which  is  of  a  yellow  colour;  but  if  the  water  contains  a  very  fmall  proportion  of 
nitre,  which  has  loft  fome  of  its  air  by  heat  (as  one  grain  in  fix  ounces),  the  gold  is  deprived  of  its  oxygen 
and  becomes  blue.     The  alkali  of  the  nitre  does  not  affift  in  producing  this  effeft.    Nitrous  acid  alone,  which 

does 


jiBhn  «f  i^itre  upon  Platina  and  Silver.  31 

fefaving  found  that  nitrei  would  diflblvc  gold,  I  tried  whether  it  would  produce  any  effeft 
upon  platina. 

It  has  been  forpierly  obferved,  that  the  grains  of  platina,  in  the  impure  ftate  in  which  it 
is  originally  found,  might,  by  being  long  heated  in  a  crucible  with  nitre,  be  reduced  to  pow- 
der. Lewis,  from  his  own  experiments  and  thofe  of  MargrafF,  thought  that  the  iron  only 
which  is  contained  in  the  grains  of  platina  was  corroded  by  the  nitre.  But  by  heating 
nitre  with  fome  thin  pieces  of  pure  platina  in  a-cup  of  the.  fame  metal,  I  found  that  the 
platina  was  eafily  diffolved,  the  cup  being  much  corroded,  and  the  thin  pieces  entirely  de- 
ftroyed.  By  diflblving  the  faline  matter  in  water,  the  greater  part  of  the  platina  was  pre- 
cipitated in  the  form  of  a  brown  powder.  This  powder,  which  was  entirely  foluble  in 
marine  acid,  confided  of  the  calx  of  platina,  combined  with  a  portion  of  alkali,  which 
could  not  be  feparated'by  being  boiled  in  water.  The  platina  which  was  retained  by  the 
alkaline  folution  communicated  to  it  a  brown  yellow  colour.  By  adding  an  acid  to  it  a 
precipitate  was  formed,  which  confided  of  the  calx  of  platina,  of  alkali,  and  of  the  acid 
which  was  employed. 

Silver  I  found  to  be  a  little  corroded  by  nitre  :  but,  as  its  action  upon  that  metal  was 
very  inconfiderable,  it  did  not  appear  to  be  deferving  of  a  more  particular  examination. 


IX. 

An  Account  of  certain  Gaufes  of  Alteration  injurious  to  the  ^lality  of  Corn,  and  the  Means  of  pre- 
venting this  Change  *.  By  B.  G.  Sage,  of  the  ci-devant  Academy  of  Sciences,  Profejfor  of 
Chemijiry  and  Mineralogy  in  the  School  des  Mines  de  la  Monnoie. 


I 


N  the  Analyfis  of  Corn,,  which  I  publiflied  in  1776,  I  have  diewn  that  when  the  corn  no 
longer  contains  glutinous  f  or  ve^eto-animal  matter,  it  affords  flour  not  adapted  to  produce 
a  good  panary  fermentation  ;  that  the  bread  is  not  white,  and  has  a  difagreeable  fade  and 
fmell  j  that  it  produces  an  opprefEon  at  the  domach,  putrid  diforders,  and  the  dry  gangrene, 
like  fmutted  ryCi  I  did  not  at  that  time  know  the  caufe  of  this  alteration  of  corn  ;  but 
difcovered  it  lad  year,  by  attending  to  the  farming  operations  in  the  corn  country  of 
Beauce,  where  I  have  obferved  that  the  method  of  houfing  or  dacking  the  corn  Was  more 
fuited  to  dedroy  than  to  preferve  it. 

In  fa£l,  the  fickle  has  fcarcely  cut  the  corn  before  it  is  colle£led  in  fheaves  to  form  fhocks,. 
or  larger  parcels,  which  are  immediately  conveyed  into  the  barns,  where  they  are  packed 

does  not  contain  its  full,  proportion  of  oxygen,  occafions  the  fame  precipitation,  unlefs  it  is  very  ftrong;  and  if  a 
mixture  of  fuch  ftrong  nitrous  acid,  and  of  a  folution  of  gold  in  nitrous  acid,  is  dropped  into  water,  the  gold  is 
deprived  of  itS|Oxygen,  and  is  precipitated  of  a  blue  colour.  Two  caufes  contribute  to  produce  this  elfeft  upon 
the  addition  of  water.  The  adhefion  of  the  calx  of  gold  to  nitrous  acid  is  by  that  means  weakened,  and  the 
oxygen  is  attrafted  more  ftrongly  to  the  imperfeft  nitrous  acid  in  confequence  of  their  attraftion  for  water  when 
they  are  united. 

*  Journal  de  Phyf.    Sep.  for  1794. 

t  Wheat  is  compofed  of  the  cortical  part  called  bran,  ftarch,  faccharine  matter,  and  the  glutinous  fubftancc. 
The  fl<ur  obtained  at  the  mills  near  Paris  is  compofed  of  i-i6th  part  of  faccharine  and  extraftive  matter, 
j.jds  ,:  white  fecula  called  ftarch,  and  i-4th  part  of  elaftic  glutinous  matter.  The  corn  of  tbefouthern  coun- 
tries contain  more.    S.  ^ 

5  a8> 


32  Spontaneous  Heat  of  Corn  dejlroys  its  Gluten. 

as  clofc  as  poflible,  without  attending  whether  the  grain  and  the  ftraw  be  dry,  as  well  astlic 
more  aqueous  herbs  which  are  cut  along  with  it.  The  confequence  is,  that  the  corn  be- 
comes heated  a  few  hours  after  it  is  put  away,  and  this  heat  is  ftronger  and  more  durable 
the  larger  and  the  damper  the  mafs.  The  heat  is  frequently  ftrong  enough  to  bake  an  egg,  ac- 
cording to  the  account  of  the  cultivators.  For  my  part,  I  could  not  hold  my  hand  in  this  maf-;, 
■which  is  as  capable  of  fpontaneous  combudion  as  flacks  of  hay  when  put  together  too  wet. 
Fire  does  not  manifefl  itfelf  fo  often  in  our  barns,  becaufe  the  air  can  fcarcely  at  ail 
penetrate  into  them,  by  reafon  of  the  very  clofeflowage.  When  I  aflced  the  farmers  why 
they  prefled  the  corn  fo  much  ?  they  affirmed,  that  their  view  was  to  prevent  its  occupying 
a.large  fpacc,  and  to  hinder  vermin  from  finding  their  way  into  it. 

When  -this  heat  is  excited  in  the  corn  newly  (lowed  away,  a  fniell  is  emitted  for  thre^ 
weeks  refembling  that  of  fermenting  beer :  it  feemed  at  firfl  as  if  aromatic  herbs  had 
been  boiled  in  the  neighbourhood. 

I  have  obferved  the  duration  of-  this  heat  for  more  than  four  months,  in  a  barn  wher  e 
"the  quantity  (lowed  away  amounted  to  a  cube  of  about  40  feet.  The  corn,  when  taken  out, 
was  rough,  ruddy,  and  more  or  lefs  decompofed  ;  fo  that  in  'the  lower  part  of  the  barn 
the  alteration  and  decompofition  of  the  glutinous  matter  was  complete,  and  the  grain  was 
no  longer  proper  for  vegetation  *.  The  bread  made  with  flour  of  this  corn  does  not  rife 
wsl!,  and,  after  baking,  exhibits  a  yellowifh  grey  colour. 

The  farmers  of  Beauce  have  a  prejudice  that  it  is  good  for  the  grain  to  fweat  and  heat, 
which  is  contrary  to  found  rcafoning :  for  in  this  cafe  the  heat  is  produced  by  fermenta- 
tion, which  cannot  take  place  but  by  the  decompofition  and  lofs  of  fome  of  the  integral 
parts  of  the  corn.  It  is  accordingly  found,  that  the  faccharine  and  glutinous  mattej  are 
-more  or  lefs  deltroyed  in  proportion  to  the  time  which  the  corn  has  remained  in  the 
heated  (late. 

If  the  (heaves  were  dry  when  houTed,  they  would  not  heat,  and  the  grain  woulB  be  pre- 
ferved  in  perfc£lion.  It  is  proper  therefore  to  fufFer  them  to  dry  in  the  field,  and  not  pack 
them  together  until  they  have  given  out  all  their  moidure.  It  will  alfo  be  of  advantage  to 
lay  them  lightly  together  indead  of  prelTing,  in  order  that  the  circulation  of  the  air  may 
carry  off  the  lad  portions  of  humidity. 

Befides  the  prefervation  of  the  grain,  another  advantage  would  be  obtained,  namely,  that 
the  draw  would  be  neither  heated  nor  mouldy.  Straw  in  this  lad  date  contrads  a  difa- 
greeabie  fmell,  which  is  repulfive  to  cattle. 

It  is  in  one  of  the  mod  fertile  corn  provinces  of  France,  in  which  the  ground  is  bed  cul- 
tivated, that  a  method  fo  prejudicial  to  the  grain  is  employed.  The  intereds  of  humanity 
being  the  fame  as  that  of  the  cultivator,  it  is  to  be  prefumed  that,  when  once  indru£led,  he 
will  change  his  praftice.  In  fa£l  his  gain  will  be  double  :  for  he  will  condantly  have 
wholefome  corn,  and  will  fell  it  at  a  higher  price  than  fuch  as  has  been  heated. 

As  the  (late  and  Quality  of  corn  is  to  be  judged  from  the  nature  and  quantity  of  the  glu- 
tinous matter,  it  is  proper  to  defcribe  the  procefs  for  extrafting  it. 

Take  four  ounces  of  wheat  flour  feparated  from  the  bran  ;  mix  it  with  water  to  form  a 
pafte.     Let  this  be  kneaded  for  a  quarter  of  an  haur,  and  afterwards  wadied  by  working  it 

*  I  think  it  would  be  proper  to  fuffer  the  corn  to  dry  in  the  Iheaf  for  the  purpofe  of  affording  wholefome 
grain ;  for  the  fermentation  alters,  weakens,  and  often  deftroys  it. 

I  with 


Apparatus  for  difengaging  Oxygen  Gas.  33 

with  the  hands  under  water,  which  is  to  be  changed  from  time  to  time.  This  wafliing  is  to 
be  continued  until  the  laft  quantity  of  water  made  ufe  of  is  no  longer  difcoloured.  The  fub- 
ftance  remaining  in  the  hands  is  the  glutinous  matter  of  a  whitiJh  grey  colour.  If  the 
corn  be  good,  this  is  elaftic  ;  (that  is  to  fay,  it  may  be  drawn  into  long  firings, -which  have  a 
difpofition  to  flirink  or  contract. )  If  the  corn  has  begun  to  heat,  it  is  fliort  or  brittle.  If  , 
it  has  fermented,  it  will  afford  none  of  this  glutinous  matter. 


X. 

Dcfcription  of  an  Apparatus  for  difengaging  Oxygen  Gas,  and  applying  it  to  the  bejl  Advantage. 
ConJlruElcd  by  J  AMES  SadlSR,  EJq.  Chemijl  to  the  Admiralty. — To  which  are  added, 
Ohjervalions  upon  the  Blonv-Pipe.     By   W.  N. 

Jr  I  G.  I.  plate  2,  reprefents  the  vertical  feftion  of  a  furnace.  The  ftiadcd  parts  denote 
brick  work.  A  is  the  afli-hole,  B  the^rate  upon  which  the  fuel  is  placed,  C  the  opening 
for  the  reception  of  the  fuel.  It  is  covered  with  a  piece  of  fire  (tone,  or  an  eartlitn  cover, 
at  all  times  except  when  a  fupply  of  fuel  is  wanted.  D  is  the  aperture  leading  to  the 
chimney  F;  and  between  D  and  F  is  a  chamber  for  the  reception  of  a  mattrafs  or  other 
veflel  ii,  to  be  expofed  to  the  adion  of  the  flame.  The  veffel  E  is  put  in  its  place,  or 
taken  out,  by  the  opening  at  the  upper  part  of  the  chamber ;  and  when  at  work,  that  open- 
ing is  clofed  by  two  pieces  of  fire  (lone,  each  of  which  covers  half  the  aperture,  and  meet* 
the  other  by  a  perfe£l  ground  edge,  having  a  notch  that  leaves  a  fpace  for  the  neck  of  the 
veflel.  Fig.  II.  is  a  ground  plan  of  the  fame  furnace,  with  the  apparatus  for  receiving  and 
applying  the  oxygen.  The  letters  B,  E,  F,  denote  the  fame  parts  as  in  fig.  i.  Fig.  III. 
exhibits  a  vertical  fc£liou  of  the  mattrafs,  and  other  apparatus,  denoted  by  the  fame  letters 
as  in  fig.  2.  E  is  the  mattrafs  containing  black  oxyde  of  manganefe.  H  is  a  refrigeratory 
through  which  the  tube  of  communication  pafles.  I  is  a  receiver  forcondenfable  vapour. 
The  elailic  fluid  pafles  through  the  tube  at  K  into  the  receiver  L,  inverted  in  another  veflel  of 
water  M  ;  the  receiver  being  fufpended  by  a  fl;ring  pafllng  over  a  pulley,  which  therefore 
admits  of  a  variation  at  pleafure  of  the  reaclion  for  extruding  the  air  through  the  blow- 
pipe N  P.  The  part  N  of  the  blow-pipe  is  of  porcelain  ;  and  a  lamp  O  is  placed  beneath 
for  the  purpofe  of  heating  the  air  before  it  iflues  from  the  orifice  P.  The  letters  G,  K, . 
and  Q5_ denote  cocks  to  be  occafionally  clofed  when  the  receiving  apparatus  is  required  to  be 
feparated  or  removed. 

The  advantages  of  this  apparatus  are,  firft;,  the  fimplicity  of  the  furnace,  which  is  appli- 
cable to  a  variety  of  ufes,  as  well  as  that  particularly  flatcd  in  this  account.  As  the  current 
of  atmofpheric  air  from  A,  through  the  grate  to  B,  D,  and  F,  docs  not  pafs  above  the  root 
of  the  paflTage  D  ;  the  upper  part  of  the  fire-place  towards  C,  where  the  combuition  can- 
not, reach,  may  be  confidercd  as  a  repofitory  for  fuel,  upon  the  principle  of  the  athanor, 
and  might,  if  required,  be  made  equally  capacious.  1  his  fuel,  before  it  arrives  rit  the  place 
of  combuftion,  ferves  alfo  as  a  cover  when  the  aftual  cover  is  taken  pff  to  fupply  the  confump'- 
tion;  befides  which,  there  is  not  the  lead  poflibility  of  deranging  or  difiurbing  tlie  veflels  on 

fuch  occafions,  as  is  too  often  the  cafe  in  tlie  common    air  furnace.     The  aperture  at   t. 

'.  -^  .  .  .^.    .  <         ...    .     , 

,'-Vot.  II.— April  1798.  F  affbrds 


j4  ContbuflnH  entited  hy  htated  OifygtH. 

affords  a  degree  of  conTcnience,  equally  obvious,  with  regard  to  the  putting  in,  placing, 
and  taking  out  the  vefFels.  Of  the  refrigeratory,  the  receiver  I,  and  the  apparatus  M  h, 
little  more  need  be  faid  than  that  they  are  conftruflred  in  the  forms  which  experience  has 
fiiewn  to  be  the  mofl  fimple  and  efficacious.  The  parts  NOP  exhibit  an  improvement 
which  is  found  to  be  of  great  importance.  Mr.  Sadler  obferved,  in  the  courfe  of  his  experi*- 
ments,  that  the  efie£t  of  the  oxygen,  when  recently  produced,  was  much  greater  than  fome 
hours  afterwards.  There  was  no  reafon  to  conclude  that  this  difference  arofe  from  any 
change  in  the  purity  of  the  fluid  :  he  therefore  concluded  that  it  muft  be  caufed  by  a 
difference  of  temperature.  When  the  cold  oxygen  is  brought  into  contacH:  with  a  com- 
buftible  body  at  a  very  elevated  temperaturt-,  it  muft  be  concluded,  that  part  of  the  caloric 
difengaged  at  the  inftant  of  combination  muft  be  employed  in  raifing  the  temperature  of 
the  mafs  of  oxygen,  and  confequcntly  that  the  intenfity  of  the  combuftion  will  be  lefs. 
He  therefore  determined  to  fupply  this  portion  of  caloric  from  another  procefs  of  com- 
buftion, carried  on  near  the  external  furface  of  the  tube  through  which  the  oxygen  is  tranf- 
mitted.  O  is  the  lamp  for  that  purpofe,  affi^rding  a  flame,  which  heats  the  tube  N,  and 
gives  an  elevated  temperature  to  the  oxygen  before  it  palTes  out  of  the  fmall  aperture  P. 
The  heat  excited  in  a  piece  of  charcoal  urged  by  this  ftream  of  oxygen  is  fo  great,  as  to 
fufe  the  pureft  fpecimens  of  native  rock  cryftal,  and  alfo  thofe  of  lime.  The  other  eff^edli 
are  llkewife  proportionally  greater. 


Ohfervations  on  the  Common  Bloiu-P'tpe. 

CHEMISTS  and  mineralogifts  are  too  well  acquainted  with  the  ufe  of  this  inftrument,  to 
require  any  long  enumeration  of  its  advantages.  To  behold  with  eafe  fuch  proceffes  as  demand 
much  labour  and  time  in  furnaces,  and  cannot  in  this  laft  fituation  be  eaiily  and  comfortably 
infpefted  ;  — to  fee  thefe  performed  in  the  open  air  in  a  few  feconds,  with  all  the  changes 
of  colour,;  ebullition,  fcoriation,  and  the  like ;  — to  remark  the  nature  of  the  vapours  which 
fly  off,  and  to  note  the  precipitation  of  metallic  fubftances  from  their  fluxes,  or  the  effefts 
they  produce  on  the  feveral  kinds  of  glafs  : — thefe  are  a  few  of  the  advantages  which  have 
brought  this  inftrument  into  eftimation. 

It  is  well  known  that  the  common  praftice  of  blowing  with  the  mouth,  though  very 
leady,  and  requiring  an  inftrument  of  inconfiderable  coft,  is  not  fo  advantageous  as  the  ex- 
trufion  of  air  by  means  of  bellows,  or  other  mechanical  contrivances.  The  air  exhaled 
from  the  lungs  has  already  been  deprived  of  part  of  its  oxygen,  and  is  loaded  with  humi- 
dity. The  procefs  of  blowing,  even  to  the  moft  fkilful,  is  attended  with  fome  fatigue,  and 
requires  a  degree  of  confinement  of  the  head  and  one  of  the  hands,  which  confiderably  di- 
minifhes  the  power,  as  well  as  the  eafe  of  the  operator.  Bellows,  at  the  price  of  two  and 
three  guineas  the  fet  with  a  few  additional  implements,  have  been  contrived  for  this 
purpofe.  It  fecmed  probable  to  me,  that  thefe  inftruments  are  larger  and  more  coftly 
than  is  requiiite.  To  afcertain  the  value  of  this  fufpicion,  I  made  the  following  expe- 
riments : 

A  blow-pipe  nearly  of  the  figure  defcribed  by  Bergmann,  whofe  internal  diameter  was 
about  one  fifth  of  an  inch  at  the  fmallcft  part,  was  inferted  through  the  cork  of  a  bottle, 
of  which  the  contents  were  17^  cubic  inches^    The  cork  was  notched  ^  fuch  a  manner 

diat 


Sxperments  on  the  Blow -Pipe.  35 

ihat  when  the  pipe  was  (luck  in  the  neck  of  the  bottle  previoufly  filled  with  water,  the 
%phole  could  be  inverted  without  any  portion  running  out,  though,  from  the  fize  of  the 
notch,  a  flight  agitation  was  fuIHcient  to  produce  that  event.  In  this  fituation  the  mouth 
was  applied  to  the  blow-pipe,  and  the  air  llrongly  blown  into  the  bottle.  The  water  im- 
mediately flowed  out,  that  is  to  fay,  in  eighteen  feconds.  The  experiment  was  twice  re- 
peated, and  the  aperture  of  the  nozlc  of  the  blow-pipe  was  -^Vth  of  an  inch.  Hence  it 
follows,  that  the  quantity  of  air  emitted  from  the  blow-pipe  was  not  quite  one  cubic  inch 
in  a  fecond.  For  it  was  17^  cubic  inches  in  eighteen  feconds.  It  will  appear  alfo  from 
an  eafy  calculation,  that  the  velocity  was  not  quite  four  feet  in  a  fecond. 

The  nozle  ufed  in  the  foregoing  experiment  was  adapted  to  the  flame  of  a  lamp  :  but 
it  was  too  large  for  the  flame  of  the  candle  called  a  fliort  eight,  which  is  of  tallow,  nine 
inches  long,  three  qrs.  inch  in  diameter,  having  (Ixteen  yarns  of  cotton  in  its  wick,  and 
weighing  4th  part  of  a  pound  avoirdupois.  The  experiments  were  repeated  with  a  nozle  well 
fuited  to  the  flame  of  this  candle.  The  aperture  of  this  laft  was  rather  more  tban  j'^th  of 
an  inch  in  diameter.  The  bottle  was  emptied  once  in  20  feconds,  and  twice  with  uncom- 
fortable exertion  in  18  feconds  each  time.  If  Ae  velocity  of  emiflion  had  been  the  fame 
in  both  experiments,  this  laft  would  have  required  about  36  feconds.  It  may  therefore  be 
inferred,  that  in  the  experiment  with  the  largeft  aperture,  the  efcape  of  air  was  fo  fpeedy 
as  confiderably  to  diminifh  the  preflurc  by  wl^ch  it  was  driven  out. 

In  order  to  afcertain  the  condenfation  of  the  air  in  the  blow-pipe,  a  fmall  quantity  of 
water  was  put  into  the  bottle,  and  the  blowing  continued  for  a  few  feconds  beneath  the 
thumb,  which  was  applied  to  the  orifice  of  the  neck.  Air  was  fufFered  to  efcape  at  the 
fame  time  through  the  lips,  fo  as  nearly  to  produce  the  fame  efi^eft  vvith  regard  to  the 
mufcles  of  the  mouth,  as  if  the  fame  had  been  emitted  through  a  blow-pipe.  When  the 
aclion  was  at  its  utmoft,  the  thumb  was  fuddenly  clofed  on  the  aperture,  and  the  bottle 
inverted.  In  this  fituation  the  line  of  the  upper  furface  of  the  water  was  carefully  marked, 
after  which  the  thumb  was  gently  withdrawn,  and  a  portion  of  the  water  flowed  out  in 
confequence  of  the  fprlng  of  the  included  air.  By  the  depreflion  of  the  water,  it  was 
found  that  the  air  had  been  condenfcd  by  about  ^th  part  of  the  whole,  and  confequently 
would  have  fuftained  a  little  more  than  an  inch  of  mercury  in  a  fimple  gage.  It  feemed 
probable,  however,  that  the  exertion  of  blowing  into  a  bottle  by  a  fliort  temporary  effort, 
might  be  very  different  from  the  fteady  aftion  of  blowing  through  a  pipe.  To  prove  this 
more  clearly,  I  bended  a  glafs  tube  nearly  of  the  fame  internal  diameter  as  the  blow-pipe 
into  a  fyphon,  the  legs  of  which  formed  an  angle  of  about  45  degrees  of  each  other.  Into 
this,  mercurywas  poured  to  occupy  feveral  inches  in  length,  and  the  tube  was  fixed  fo  that 
one  of  its  legs  continued  vertical,  while  the  other  was  acceffible  to  the  mouth.  Upon 
blowing  into  the  latter  orifice,  it  was  found  that,  by  an  eafy  or  moderate  a£lion,  the  mer- 
cury was  fuftained  to  the  height  of  about  -,*oths  of  an  inch  above  its  level ;  that  when  the 
preflTure  was  ftrong,  the  height  was  about  half  an  inch  ;  and  that  it  was  pofTible,  by  very 
ftrong  exertion,  to  keep  the  mercury  at  one  inch  :  but  the  lips  foon  became  tired.  The 
mercury  might  indeed  be  urged  to  near  two  inches,  but  not  in  a  way  that  could  have  been 
maintained  for  even  an  extremely  fhort  time  in  a<5tual  work. 

From  thefe  fa£ts,  if  we  take  half  an  inch  for  the  medium  ftation  of  the  gage,  the  preflurc 

F  2  for 


•36  Apparatus  for  Experiments  -with  the  Blow-Pipe. 

for  extruding  the  air  will  anfwer  to  about  a  quarter  of  a  pound  avoirdupois  upon  each 
fquare  inch  of  furface,  which  is  not  more  than  an  eighth  part  of  the  preflure  in  the  regu- 
lating belly  o  f  tlie  blowing  machines  at  our  great  foundries.  I  think  the  quantity  of  one 
cubic  inch  per  fecond  is  quite  as  much  and  probably  more  than  iflues  out  of  the  blow-pipe 
in  any  courfe  of  experiment.  A  pair  of  bellows  capable  of  extruding  fomewhat  more  than 
two  cubic  incites  at  a  flroke,  would  confequently  fupplyas  much  air  as  the  pipe  would  de- 
liver, provided  the  ftrokes  fuccecded  each  other  about  once  in  two  feconds,  which  appears 
to  be  a  convenient  rate  of  working,  and  by  no  means  too  quick.  In  very  fmall  bellows  the 
internal  contents  may  be  eflimated  at  one  third  of  the  contents  of  a  parallelopipedon,  or 
fquare  box  capable  of  circunifcribing  the  bellows  when  open.  As  a  full  allowance,  let 
us  fuppofe  the  contents  of  this  imaginary  box  to  be  eight  cubic  inches,  and  its  depth  two 
inches.  Its  upper  furface  muft  then  be  equal  to  four  fuperficial  inches.  That  is  to  fay,  a 
"pair  of  bellows  fully  fufficient  to  fupply  the  blow-pipe  will  not  require  larger  dimenfions 
than  three  inches  in  length,  one  inch  and  a  half  in  width,  with  a  lift  of  one  inch  and  a  half 
for  each  flroke.  The  fame  efFeiSl  may  be  produced  by  a  fyringe  one  inch  in  diameter,  and 
two  inches  and  a  half  long. 

The  refervoir  for  the  air  mp.y  either  be  another  pair  of  bellows  rather  larger,  and  difpofed 
to  fhut  by  a  weight  or  a  fpring;  or  it  may  be  fimply  a  veflel  of  fufficient  capacity  to 
receive  the  air  from  the  bellows,  and  emit  i^  in  a  conftant  ftream  by  virtue  of  its  fpring 
under  condenfation,  in  the  fame  manner  as  water  is  emitted  from  the  air  veflel  of  a  fire- 
engine.  TliC  emifTion  of  air  from  fuch  a  veflel  may,  in  a  loofe  way,  be  taken  to  be  at  half 
the  velocity  of  its  introdudlion  ;  and,  confequently,  at  the  end  of  every  ftroke  the  veflel 
will  contain  half  as  much  more  air,  than  the  medium  ftate  of  condenfation,  as  amounts  to 
the  whole  contents  of  the  bellows ;  and  at  the  beginning  of  every  ftroke,  the  veflTel  will 
contain  half  as  much  lefs  than  that  quantity.  From  thefe  confiderations,  it  appears  that 
the  fteady  ftream  from  a  fire-engine  could  not  be  produced  but  by  two  pumps  alternately 
acling,  and  that  the  air  anfwers  fcarcely  any  other  purpofe  in  the  fmall  air-veflels  of  thofe 
engines,  than  that  of  rendering  the  intFufion  of  the  non-elaftic  water  lefs  fudden  and  "vio- 
lent. It  will  alfo  appear  from  calculation,  (as  it  does  from  prailice,  in  the  regulating  bellies 
of  blowing  engines,  on  which  the  re-aftion  is  afforded  by  a  variable  force  fomewhat  refem- 
bling  the  fpring  of  tlie  air)  that  a  very  large  veflel  is  required  to  give  a  practical  uniformity 
to  the  emitted  ftream,  when  the  aiflion  of  intrufion  is  not  conftant.  Hence  it  appears, 
that  an  air  vtfl'el  cannot  be  ufcd  to  advantage,  unlefs  the  bellows  to  our  fmall  apparatus  be 
made  double  by  two  fixed  outer  boards,  with  valves  opening  inwards,  and  a  moveable 
diaphragm  alternating  between  them,  and  forcing  the  air  through  valves  opening  into  one 
common  nozle— or  unlefs  the  fyringe,  if  ufed,  be  made  to  adl  both  ways,  namely,  by  the 
returning  as  well  as  by  the  direct  ftroke.  A  very  neat  and  compadl;  apparatus  for  the 
blow -pipe  might  be  made  in  this  way;  but  it  is  probable  that  the  confiderations  and  their 
advantages  may  be  more  particularly  applicable  to  the  large  engines  at  the  fmelting- 
works. 


XL  AJ}.ort 


■    Life  of  PeKetier.  37 

XI. 

A  port  Account  of  the  Life  of  PellkTIER.  Read  at  the  Public  Sittitig  of  the  National  Jnjlitute 
of  France,  the  i^thVeudemiaire,  in  the  Tear  V I.  By  CiTIZEN  LaSSUS,  Secretary  to  the 
Clafs  of  Natural  Philofophy  and  Mathematics. 

J  N  the  courfe  of  the  lafl:  tilmeftre  we  have  had  fhe  misfortune  to  lofe  one  of  our  col- 
leagues, Bertrand  Pelletier,  born  at  Bayonne  in  1761.  His  life  was  confined  to  the  fliort 
fpace  of  36  years ;  but  his  aftions  have  left  an  impreffion  on  the  minds  of  men  which  time- 
fhall  not  efface. 

It  frequently  happens  that  young  men,  fmcerely  defirous  of  inftrudion,  have  no  means 
or  place  where  they  can  be  aflifted  in  the  development  of  their  natural  talents,  no  mafter 
who  may  point  out  the  direft  road  to  fcience,  and  that  order  and  method  without  which 
the  efforts  of  the  individual  too  often  lead  him  from  the  obje£l:  of  his  purfuit,  inftcad  of 
bringing  him  nearer  to  it.  This  was  not  the  cafe  with  young  Pelletier.  He  found  every 
advantage  in  his  father's  houfe,  where  he  received  the  firfl:  elements  of  the  art  of  which  he 
was  afterwards  the  ornament;  and  his  fubfequent  progrefs  was  made  under  our  colleague 
Darcet,  who  having  remarked  in  him  that  fagacity  which  may  be  called  the  inftinia  of 
fcience,  admitted  him  among  the  pupils  attached  to  the  chemical  laboratory  of  the  college 
of,  France.  Five  years  of  conftant  application  and  lludy  under  fuch  a  mafter,  who  was 
himfelf  formed  by  nature,  perfe£led  by  experience,  and  affeftionately  difpofed  towards  his 
pupil,  afforded  this  young  man  a  ftock  of  knowledge  very  unufual  at  his  age.  He  foon 
gave  a  convincing  proof  of  this,  by  publifning,  at  the  age  of  21,  a  fet  of  very  excellent  ob- 
fervations  on  the  arfenical  acid.  Macquer,  by  mixing  nitre  with  the  oxyde  of  arfenic,  had 
difcovered  in  the  refidue  of  this  operation  a  fait  foluble  in  water,  fufceptible  of  cryftalliza- 
tion  in  tetrahedral  prifms,  which  he  denominated  the  neutral  arfenical  fait.  It  is  the 
arfeniate  of  potafli.  He  was  of  opinion  that  no  acid  could  decompofe  it ;  but  Pelletier 
fhowed  that  the  fulphuric  acid  diftilled  from  it  does  difengage  the  acid  of  arfenic.  He 
fhowed  the  true  caufe  why  the  neutral  arfenical  fait  is  not  decompofable  in  doled  veffels, 
and  particularly  the  order  of  affinity  by  which  the  fait  itfelf  is  formed  in  the  diftillation  of 
the  nitrate  of  potafli,  and  the  white  oxyde  of  arfenic.  He  explains  in  what  refpecls  this  fait 
differs  from  what  Macquer  called  the  liver  of  arfenic.  Pelletier  had  been  anticipated  in 
thiswork  by  Scheele,  by  Bergmann,  by  the  academicians  of  Dijon,  and  by  our  colleague 
Berthollet ;  but  he  poffeffed  at  leaft  the  merit,  in  the  firfl;  effay  of  his  power.--,  of  having 
clearly  developed  all  the  phenomena  of  this  operation,  by  retaining  arul.even  determining 
the  quantity  of  gas  it  was  capable  of  affording.  After  the  fame  principles  it  was  that  he 
decompofed  the  arfenico-ammoniacal  fait,  by  fhowing  how,  in  the  decompofition  of  this 
laft,  the  pure  arfenical  acid  is  obtained  in  the  form  of  a  deliquefcent  glafs.  In  this  work 
we  may  obferve  the  fagacity  with  which  he  was  enabled  to  develope  all  the  phenomena  of 
thefe  compofitions  and  decompofitions,  by  tracing  thofe  delicate  threads  of  fcieniific  cou- 
ne£lion  which  connedt  the  feries  of  fafts,  and  are  imperceptible  to  ordinary  minds. 

Encouraged  by  the  fuccefs  of  thefe  firfl:  works,  which  he.prefented  with  the  fenfibility  of 
grateful  attachment  to  his  infl:ru£lor,  he  communicated  his  obfervations  on  the  cryft^alliza- 
tion  of  fulphur,  cinnabar,  and  the  deliquefcent  falts  ;  the  examination  of  7.eolites,  particu- 
larly the  falfe  zeolite  of  Fribourg  in  Brifgaw,  which  he  found  to  be  merely  an  ore  of  zinc ; 
2  obfervatious 


3?  Account  of  the  Lift  tf  PelUtier. 

Tjbfervations  on  the  dephlogifticated  or  oxygenated  muriatic  acid,  relative  to  tlie"abforptIon 
of  oxygene;  on  the  formation  of  ethers,  particularly  the  muriatic  and  the  acetous;  and  feve- 
ral  memoirs  on  the  operation  of  phofphorus  made  in  the  large  way,  its  converfion  into 
phofphoric  acid,  and  its  combination  with  fulphur  and  moft  metallic  fubftances. 

It  was  by  his  operations  on  that  moft  aftonifliing  produdlion  of  chemiftry,  phofphorus, 
that  he  burned  himfelf  fo  dangeroufly  as  nearly  to  have  loft  his  life.  After  the  cure  of  his 
wound,  which  confined  him  to  his  bed  for  fix  months,  he  immediately  began  the  analyfisof 
the  various  plumbagos  of  France,  England,  Germany,  Spain,  and  America,  and  found 
means  to  give  novelty  and  interefl  to  his  work  even  after  the  publication  of  Scheele  on  the 
fame  objedl.  The  analyfis  of  the  carbonate  of  barytes  led  him  to  make  experiments  on  ani- 
mals, which  prove  that  this  earth  is  a  true  poifon,  whether  it  be  adminiftered  in  the  form 
of  the  native  carbonate  of  barytes,  or  whether  it  be  taken  from  the  decompofition  of  the 
fulphate,  even  though  again  combined  with  another  acid. 

Chemifts  have  given  the  name  of  Strontian  to  a  newly-difcovered  earth,  from  the  name 
of  the  place  where  it  was  firft  found.  Pelletier  analyfed  it,  and  difcovered  it  in  the  ful- 
phate of  barytes.  He  likewife  analyfed  the  verditer  of  England,  of  which  painters  and 
paper-hangers  make  fo  much  ufe.  He  difcovered  a  procefs  for  preparing  it  in  the  large 
way,  by  treating  with  lime  the  precipitate  obtained  from  the  decompofition  of  nitrate  of 
copper  by  lime.  By  his  procefs,  verditer  is  afforded  equal  in  beauty  to  that  which  comes 
from  England.  He  was  likewife  one  of  the  firft  chemifts  who  fliowed  the  poflibility  of 
refining  bell  metal,  and  feparating  the  tin.  His  firft  experiments  were  made  at  Paris; 
after  which  he  repaired  to  the  foundry  at  Romilly  to  verify  them  in  the  large  way.  The 
following  year  he  was  received  a  member  of  the  Academy  of  Sciences  at  Paris,  and  fhortly 
afterwards  went  to  La  Fere,  with  our  colleague  Borda  and  General  Daboville,  to  aflift  in 
experiments  upon  a  new  gunpowder.  Being  obliged,  in  order  to  render  his  experiments 
tnore  decifive,  to  pafs  great  part  of  the  day  in  the  open  air  during  a  cold  and  humid  feafon, 
his  health,  which  was  naturally  delicate,  became  confiderably  impaired.  He  began  to  re- 
cover his  health,  when  he  again  became  the  vidlim  of  his  zeal  for  the  fcience  he  fo  fuc- 
cefsfully  cultivated.  He  had  nearly  perifticd  by  refpiring  the  oxygenated  muriatic  acid 
gas.  A  violent  attack  of  convulfive  afthma,  which  returned  during  feveral  days,  was  the 
firft  confequence  of  this  unhappy  accident.  The  diforder  then  feemed  to  abate,  but  it  was 
incurable.  The  afliftance  of  art  was  infu/Ecient  to  fave  him,  and  he  died  of  a  pulmonary 
confumprion  in  the  flower  of  his  age. 

Such  was  the  man  whofc  premature  lofs  we  now  lament.  His  attachment  for  the 
fcience  to  which  he  had  devoted  himfelf,  remained  during  the  whole  of  his  exiftcnce,  and 
in  the  laft  moments  of  his  life  it  formed  an  interefting  objeft  of  his  converfation.  He 
poflefled  that  aftivity  of  mind  fo  neceflary  to  the  refearch  of  truths  which  are  inacceflible 
to  men  of  cold  and  languid  fentiments.  As  a  man  of  fcience,  his  reputation  is  bright  and 
unblemiftied.  As  a  citizen,  his  private  virtues,  his  probity  and  good  conduct  will  long 
continue  objcfts  of  regret. 


XII.  ExtraBi 


Figure y  Rotation,  and  PrejeSlton  of  tht  Earth.  39 

XII. 

ExtraEis  from  the  Syfeme  dti  Monde  of  M.  La  Place  *. 

J.  H  I  S  work  of  La  Place  explains  the  leading  points  of  the  fyftem  of  the  world.  It  is 
as  it  were  an  abllraft  of  a  large  work,  in  which  this  profound  geometer  propofes  to  treat 
the  fame  objcfls  by  the  principles  of  the  moft  fublime  geometry,  and  which  he  promifcs 
foon  to  publifh.     I  fliall  copy  fome  of  the  refults  of  this  author. 

"  The  degree  meafured  at  the  Cape  of  Good  Hope  in  37"  fouth  latitude  f,  is  found  to 
be  307999,8  feet,  which  is  very  nearly  the  fame  as  the  degree  of  France,  under  the  parallel 
of  50",  and  greater  than  that  which  was  meafured  in  Pcnnfylvania,  at  the  latitude  of  43°  56, 
of  which  the  length  is  no  more  than  307195,2  feet.  The  degree  of  the  Cape  is  alfo 
greater  than  the  degree  meafured  in  Italy  in  the  latitude  of  47''  80,  which  was  found  to  be 
307680,6  feet.  Neverthelefs  it  ought  to  be  fmaller  than  every  one  of  thefe  degrees,  if 
the  earth  were  a  regular  folid  formed  by  the  revolution  of  a  meridian  perfectly  alike  on 
each  fide  of  the  equator.  Every  fa£t  leads  us  to  conclude  that  this  is  not  the  cafe."  V9I.  I. 
page  105. 

He  concludes,  that  the  terrcftrial  meridian  is  a  line  of  double  curvature. 

"  Terreftrial  bodies  fituated  under  the  equator  defcribe,  by  virtue  of  the  rotation  in  each 
fecond  of  time,  an  arc  of  40"  1395  of  the  circumference  of  the  terreftrial  equator.  The 
radii  of  this  equator  being  19634778  feet  very  nearly,  the  verfed  fine  of  this  arc  is 
0,0389704  feet.  Gravitation  caufes  bodies  to  fall  at  the  equator  through  a  fpace  of 
1 1,23585  feet  in  one  fecond.  The  central  force  neceffary  to  retain  bodies  at  the  furface  of 
the  earth,  and  confequently  the  centrifugal  force  arifing  from  its  rotatory  motion,  is  to  gra- 
vity at  the  equator  in  the  proportion  of  i  to  288,3.  The  centrifugal  force  diminifhes  the 
weight,  and  bodies  do  not  fall  at  the  equator  but  by  virtue  of  the  difference  of  the  true 
force.  If  we  therefore  ufe  the  word  gravity  to  denote  the  total  weight  which  would  take 
place,  exclufively  of  the  diminution  it  undergoes,  the  centrifugal  force  at  the  equator  is 
extremely  near  -j^?*^  P'*'"'  ^^  gravity.  If  the  rotation  of  the  earth  were  17  times  more 
rapid,  the  arc  defcribed  in  a  fecond  at  the  equator  would  be  17  times  greater,  and  its  verfed 
fine  would  be  289  times  more  confiderable.  The  centrifugal  force  would  then  be  equal  to 
gravity,  and  bodies  would  ceafe  to  prefs  or  weigh  towards  the  earth  at  the  equator."^ 
Page  263. 

••  To  explain  the  double  motion  of  rotation  and  progreflion  in  the  earth,  it  is  fufficient 
that  the  fuppofition  be  admitted  of  the  primitive  impulfe  having  been  given  at  a  fmall 
diftance  from  its  centre  of  gravity  -,  which  diftance,  fuppofing  the  planet  to  be  homogeneous^ 
muft  have  been  nearly  the  -rs-d'h  part  of  its  radius."  Page  299. 

"  The  probability  is  infinitely  fmall,  that  the  original  projedionof  the  planets,  fatellites, 
and  comets,  ftiould  have  pafled  through  their  centres  of  gravity.  All  thefc  bodies  muft 
therefore  have  a  rotative  motion.  From  a  fimilaf  reafon,  the  fun,  which  turns  on  its  axis,, 
muft  have  received  an  impulfe,  which  not  having  pafled  through  its  centre  of  gravity,  car-^ 

*  Expofition  du  Syftcme  du  Monde,  par  Pierre  Simon  La  Place,  de  I'lnilitut  National  de  France  et  du  Bureau 
dcs  Longitudes,  z  vol.  in  Svo.  A  Paris  de  I'lmprimeric  du  Cercle  Social,  Rue  du  Theatre  Franjois,  No.  4,  — I 
have  not  the  work,  but  tranflate  from  Dr.  Lametherie,  in  the  Journal  de  Pbyfique,  Auguft  1794. 

'jr  The  autUer  divides  tJK  circle  into  400  parts. 

ties 


4^  Syjiem  of  the  World. — Pendulums.-— Planetary  Atmofpheres. 

ries  it  through  fpace  with:  the  planetary  fyftem,  unlefs  this  mottoti  be  fup  pofed  to  have 
been  deftroyed  by  an  impulfe  in  the  oppofite  direction ;  a  circumftance  by  no  means 
probable.- 

'  "  '/he  impulfe  given  to  an  homogeneous  fphere,  in  a  dire£l:ion  which  does  not  pafs 
through  its  centre,  will  caufe  it  to  revolve  conflantly  round  the  diameter,  which  is  perpendi- 
cular to  a  plane  pafTmg  tlirough  its  centre,  and  the  line  of  direflion  of  the  imprefled  force. 
New  forces  afling  on  all  its  parts,  and  of  which  the  refult  paffcs  through  its  centre,  will 
not  change  the  parallelifm  of  its  axis  of  rotation.  Thus  it  is  that  the  axis  of  the  earth 
remains  always  nearly  parallel  to  itfelf-in  its  revolution  round  the  fun,  without  its  being 
neceflary  to  fuppofe,  with  Copernicus,  an  annual  motion  of  the  poles  of  the  earth  round 
ihofe  of  the  ecliptic. 

*'  If  the  body  poflefs  a  certain  figure,  its  axis  of  rotation  may  change  every  inftant.  The 
determination  of  thefe  changes,  whatever  may  be  the  forces  afting  on  the  bodies,  is  one  of 
the  molt  interefling  problems  of  mechanics  refpefting  hard  bodies,  on  account  of  its  con- 
nexion with  the  preceflion  of  the  equinoxes,  and  the  libration  of  the  moon.  The  folution 
of  this  problem  has  led  to  a  curious  and  very  ufeful  refult ;  namely,  that  in  all  bodies  there 
cxift  three  axes  perpendicular  to  each  other,  round  which  the  body  may  turn  uniformly 
when  not  folicited  by  external  forces.  On  this  account  thefe  axes  have  been  called  principal 
axes  of  rotation. 

"  A  body  or  fyflem  of  bodies,  poflefling  weight,  and  of  any  figure  whatever,  ofcillating 
round  a  fixed  and  horizontal  axis,  forms  a  compound  pendulum.  No  other  pendulum 
cxifts  in  nature.  The  fimple  pendulums  fo  frequently  treated  of  are  pure  geometrical  con- 
ceptions, proper  to  Amplify  the  objects  of  difcuffion.  It  is  eafy  to  refer  to  thefe  fuch  com- 
pound pendulums  as  have  their  parts  immoveably  fixed  together.  If  the  length  of  the 
fimple  pendulum,  whofe  ofcillations  are  ifochronou^  with  thofe  of  the  compound  pendulum, 
be  multiplied  by  its  total  mafs,  and  by  the  diftance  of  it«  centre  of  gravity  from  the  axis  of 
ofcillation,  the  produft  will  be  equal  to  the  fum  of  the  produiSts  of  each  particle  of  the 
compound  pendulum,  multiplied  by  the  fquare  of  its  diftance  from  the  axis.  It  is  by 
means  of  this  rule,  difcovered  by  Huyghens,  that  experiments  with  compound  pendulums 
have  been  applied  to  (hew  the  length  of  the  fimple  pendulum,  which  beats  feconds." 

The  author  enters  into  a  confiderable  detail  refpe£ling  the  atmofpheres  of  the  planets. 
"  In  all  the  changes  to  which  the  atmofpherc  is  fubjed:  (fays  he,  vol.  ii.  p.  128.)  the  fum 
of  the  produdls  of  the  particles  of  the  revolving  body  and  its  atmofphere,  multiplied  re- 
fpedlively  by  the  areas  they  defcribe  round  the  common  centre  of  gravity,  the  radii  being 
projedted  on  the  plane  of  the  equator,  remain  the  fame  in  equal  times.  Suppofing,  there- 
fore, that,  by  any  caufe  whatever,  the  atmofphere  fliould  become  contradled,  or  that  part 
thereof  fliould  become  condenfed  on  the  furface  of  the  body,  the  rotatory  motion  of  the 
body  and  its  atmofphere  would  be  accelerated  :  for,  the  radii  veSores  of  the  areas  de- 
fcribed  by  the  particles  of  the  original  atmofphere  becoming  fmaller,  the  fum  of  the  pro- 
du6ls  of  all  the  particles,  by  their  correfponding  areas,  cannot  remain  the  fame  unlefs  the 
vetecity  be  augmented. 

"  The  atmofphere  is  flattened  towards  the  poles,  and  fwelled  out  at  the  equator.  But 
this  oblatenefs  has  its  limits ;  and  in  the  cafe  where  it  is  greateft,  the  ratio  of  the  polar  and 
equatorial  diameter  is  as  two  to  three. 

-        .    .  "  The 


Ffrm/iiion  ef  Planets  from  the  S^lar  Atmofphere,  a\ 

"  The  atmofphere  cannot  extend  itfelf  at  the  equator  to  a  greater  diftance  than  to  the 
place  where  the  centrifugal  force  is  exa£lly  equal  to  the  force  of  gravity.  With  regard  to 
the  fun,  this  point  is  remote  from  its  centre  to  a  diftance  meafuring  the  radius  of  the 
orbit  of  a  planet  which  would  make  its  revolution  in  the  fame  period  as  that  luminary  em- 
ploys in  its  rotation.  The  filar  atmofphere  cannot  therefore  extend  to  the  orbit  of  Mercury  ;  and 
confequently  it  cannot  produce  the  zodiacal  light,  which  appears  to  extend  even  beyond 
the  orbit  of  the  earth. 

"  The  point  where  the  centrifugal  force  balances  that  of  gravitation  is  nearer  the  body 
the  more  rapid  its  rotation.  If  we  conceive  the  atmofphere  to  extend  as  far  as  this  lihiit, 
and  afterwards  to  contra£l  and  condenfe  by  cooling  at  the  furface  of  the  bcjdy,  the  motion 
of  rotation  will  become  more  and  more  rapid,  and  the  extreme  limit  will  continually  ap- 
proach towards  the  centre.  The  atmofphere  will  therefore  fucceffively  in  the  place  of  the 
equator  abandon  zones  of  fluid,  which  will  continue  to  circulate  round  the  body,  becaufe 
their  centrifugal  force  is  equal  to  their  gravity.  But  as  this  equality  does  not  obtain  with 
regard  to  the  parts  of  the  atmofphere  diftant  from  the  equator,  they  will  not  ceafe  to  ap- 
pertain to  the  planet.  It  is  probable  that  the  rings  of  Saturn  are  fimilar  zones  abandoned 
by  its  atmofphere."  (Vol.  ii.  p.  125.) 

"  As  the  motions  of  the  planets  and  their  fatellltes  are  performed  nearly  in  the  fame 
plane,  we  muft  fuppofe  one  caufe  to  have  adted  on  all  thefe  bodies ;  and  from  the  prodi- 
gious diftances  between  them,  it  muft  have  been  a  fluid  of  immenfe  extent.  To  have  given 
them  in  the  fame  direclion  a  motion,  nearly  circular,  about  the  fun,  it  is  necefl"ary  that  the 
fluid  muft  have  furrounded  that  ftar  as  an  atmofphere.  The  confideration  of  the  planetary 
movements  lead  us  therefore  to  think,  that  by  virtue  of  an  exceflive  heat  the  atmofphere  of 
the  fun  was  originally  extended  beyond  the  orbits  of  all  the  planets,  and  that  it  gradually 
contra6led  in  procefs  of  time  to  its  prefent  limits.  Thefe  elfedts  may  have  taken  place 
by  caufes  fimilar  to  that  which  occafioned  the  ftrong  light  for  feveral  months  in  the  famous 
flar  which  in  the  year  1572  appeared  all  at  once  in  the  conftellation  of  Caffiopeia. 

"  The  great  eccentricity  of  the  orbits  of  the  comets  leads  to  the  fame  refult.  It  evi- 
dently indicates  the  difpofition  of  a  great  number  of  lefs  eccentric  orbits  ;  a  circumftance 
which  fuppofes  an  atmofphere  round  the  fun  extending  beyond  the  perihelia  of  the  ob- 
fervable  comets,  which,  by  deftroying  the  motions  of  thofe  which  happened  to  pafs  within 
it  during  the  time  of  its  greateft  extent,  united  them  to  the  body  of  the  fun.  Hence  it 
follows,  that  no  other  comets  can  at  prefent  be  in  exiftence,  but  fuch  as  were  at  that  time 
beyond  that  interval.  And  as  we  cannot  obferve  any  comets  but  thofe  which  come  near 
the  fun  in  their  perihelium,  their  orbits  muft  be  very  eccentric.  It  alfo  follows,  that  their 
inclinations  muft  offer  the  fame  irregularities  as  if  thefe  bodies  had  been  projefted  cafually ; 
becaufe  the  folar  atmofphere  has  not  influenced  their  motions.  The  long  time  employed 
by  the  comets  in  their  revolutions,  the  great  eccentricity  of  their  orbits,  and  the  variety  of 
their  inclinations,  are  therefore  very  naturally  explained  by  means  of  this  atmofphere. 

••But  in  what  manner  have  the  movements  of  revolution  and  rotation  of  the  planets  been 
cflTefted  ?  If  thefe  bodies  had  penetrated  as  fuch  into  the  atmofphere  of  the  fun,  its  refiftancc 
muft  have  caufed  them  to  fall  to  its  furface.  We  may  therefore  conjefture  that  they  were  - 
formed  at  the  fucceffive  limits  of  that  atmofphere,  by  the  condenfation  of  the  zones  which 
it  muft  have  abandoned  in  the  plane  of  its  equator  during  its  cooling  and  condenfation  at 
Vol.  II. — April  1798.  G  th« 


4.2  Whether  a  Comet  mayjir'iie  and  dejirey  the  EartS. 

the  furface  of  that  ftar.  We  may  alfo  conjefture,  that  the  fatellites  have  been  formed  in  *• 
like  manner  by  the  atmofpheres  of  the  planets.  The  five  phenomena  abovementioned  natu-^ 
rally  flow  from  thefe  hypothefes,  to  which  the  rings  of  Saturn  afford  additional  probability." 
(Vol.  ii.  p.  301.) 

The  five  phenomenaenumerated  by  the  author  are  :  (i)  The  motions  of  the  planets  in  the 
fame  dire£lion  and  nearly  in  the  fame  plane.    {2)  The  motions  of  the  fatellites  in  the  fame 
direftion  as  the  rotations  of  their  planets.      (3)  The  rotations  of  thefe  different  bodies  and^ 
of  the  fun  in  the  fame  dire£tion  as  their  projeftile  motion,  and  in  planes  very  little  differ- 
ing from  each  other  ;  andlaftly,  (4)  The  eccentricity  of  the  cometary  orbit&, 

This  great  eccentricity  of  the  comets,  and  their  motions  in  all  direftions,  appear  to  the 
author  a.fufficient  reafon  to  conclude,  that  their  origin  is  different  from  that  of  the  planets. 
He  afterwards  enquires  into  the  probability  that  a  comet  may  flrike  the  globe  of  the  earth, 
and  deftroy  its  prefent  regularity  of  appearance,  &c. 

Thefe  are  his  words,  (vol.  ii.  p,  60.)  "  The  fears  which  the  appearance  of  comets  at 
that  time  infpired,  were  fucceedcd  by  an  apprehenfion  of  another  nature  ;  left,  among  the 
great  number  which  traverfe  the  planetary  fyftem  in  every  dire£tion,  one  of  them  fliould 
deftroy  the  earth.  They  pa/sfo  rapidly  near  us,  that  the  effeB  of  their  attraBion  is  not  to  he 
feared.  It  is  only  by  actually  ftriking  the  earth  that  they  could  produce  the  dreadful  effe£l  : 
but  the  (hock,  though  poffible,  is  fo  very  improbable  in  the  courfe  of  an  age  ;  it  would  re- 
quire foextraordlnary  a  chance  for  the  concurrence  of  two  bodies  fo  fmall  with  refpe£t  tO' 
the  immenfity  of  the  fpace  in  which  they  move,  that  no  reafonable  ground  of  fear  can  be 
maintained  in  this  behalf.  Neverthelefs,  the  fmall  probability  of  fuch  an  event,  if  it  be  con- 
fidcred  with  rcfpeft  to  a  long  feries  of  ages,  may  become  very  great.  It  is  eafy  to  imagine 
the  effects  of  fuch  a  fliock  upon  the  earth.  The  axis  and  rotatory  motion  being  changed, 
the  feas  abandon  their  former  pofition,  and  rufli  to  the  new  equator ;  great  part  of  the 
men  and  animals  drowned  in  this  univerfal  deluge,  or  deftroyed  by  the  violent  ftrokc 
jmprefled  on  the  terreftrial  globe  ;  entire  fpecies  annihilated  ;  all  the  monuments  of  human 
induftry  fwept  away: — fuch  are  the.  difafters  which  might  enfue  from  the  fhockof  a  comet. 
We  fee  therefore  why  the  ocean  has  formerly  covered  the  high  mountains,  on  which  it  has 
left  indubitable  marks  of  its  prefence  •,  how  the  plants-and  animals  of  the  fouth  may  have 
exifted  in  the  climates  of  the  north,  where  their  remains  and  impreftions  appear ;  and  laftly,. 
by  an  event  01  this  kind,  we  may  explain  the  novelty  of  the  moral  worlds  the  regular  proceffes- 
of  which  can  fcarcely  be  traced  beyond  three  thoufand  years.  The  human  fpecies  reduced,, 
to  a  very  fmall  number  of  individuals,  and  to  the  moft  deplorable  ftate,  entirely  occupied 
for  a  long  feries  of  time  In  the  care  of  its  own  prefervation,  muft  have  totally  loft  the  re- 
membrance of  the  fciences  and  the  arts  ;  and  when  the  progrefs  of  civilization  gave  efEcacy  to 
wants  of  lefs  immediate  preflure,  it  became  neceflary  to  repeat  again  the  various  gradations 
of  invention,  as  if  men  had  then  for  the  firft  time  been  placed  on  the  earth.  But  however 
adequate  the  caufe  may  be  to  thefe  phenomena,  for  which  It  Is  afligned  by  fomc  phllo- 
fophers,  I  repeat,  that  we  may  be  perfectly  at  our. eafe,  with  regard  to  fo  terrible  an  event, 
during  the  (hort  interval  of  life  individusl." 


XIII.  On 


^cid  of  Lemons  prepared  in  the  Large  Way.  43 

XIIL 

On  tie  Preparation  of  concrete  Aid  of  Lemons.     By  DiZEy  Apothecary  in  Chief  to  the  French 
Jrmy,  charged  -with  the  InfpeBion  efthe  General  Magazine  of  Medicines  *. 

X  HOUGH  nature  prefents  us  with  the  citric  acid  nearly  in  a  difengaged  ftate,  it  is 
neverthelefs  confounded  in  lemon  juice  with  an  extraftive  mucilaginous  matter,  which  op- 
pofcs  the  union  of  its  cryftallizable  particles,  and  which  cannot  be  feparated  by  the  fimplc 
procefs  of  evaporation  and  expofure  to  cryftalllze. 

Scheele  was  the  iirft  who  obtained  this  acid  in  the  foHd  form.  In  the  year  1774,  Georgius 
in  Sweden,  and  afterwards  Du  Buiflbn  in  France,  publiflied  obfervations  on  the  method  of 
concentrating  and  preferving  lemon  juice.  Although  their  labours,  as  well  as  the  experi- 
ment of  Stahl  and  Guyton,  could  not  determine  the  cryftalllzation  of  this  acid,  it  is  never- 
thelefs certain  that  their  refearches  were  very  ufeful  to  affift  Scheele  in  his  difcovery  of  tht 
procefs  he  has  left  us. 

I  availed  myfelf  of  an  opportunity  to  repeat  the  procefs  of  Scheele  in  the  large  way,  ani 
to  infift  on  an  eflentlal  obfervation,  which  that  chemift  has  not  fufEciently  developed  }  for 
it  is  one  of  tlie  neceflary  conditions  for  fuccefs  in  the  cryftallization  of  this  vegetable  acid. 
Scheele,  after  feveral  unfavourable  attempts,  advifes  the  feparation  of  the  extraftive  and 
mucilaginous  matter  of  lemon  juice,  by  uniting  the  citric  acid  to  thebafis  of  calcareous  car- 
bonate, with  which  it  forms  a  citrate  of  lime,  that  precipitates  on  account  of  its  fparing  fo- 
lubllity,  while  the  extractive  and  mucous  matter  remains  diflblved  in  the  fluid.  This  citrate 
of  lime  is  afterwards  decompofed  by  a  fufficient  quantity  of  fulphuric  acid  diluted  with 
water,  with  the  precaution  to  add  an  excefs  of  this  laft  acid.  The  fulphuric  acid  feizes  the 
lime  from  the  citric  acid,  and  forms  a  fulphate,  -which  falls  to  the  bottom  becaufe  nearly 
infoluble ;  while  the  citric  acid,  being  fet  at  liberty,  is  diflblved  in  the  water  with  which 
the  fulphuric  acid  was  diluted. 

Filtration  and  wafliing  with  cold  water  feparate  the  citric  acid  entirely  from  the  fulphate 
of  lime,  and  it  may  be  afterwards  obtained  in  the  concrete  ftate  by  evaporation  in  ftone- 
ware  veflels,  at  the  temperature  of  boiling  water.  I  have  oWcrved  that  it  is  very  ufeful  to 
•fufpend  the  evaporation  every  two  days,  in  order  to  permit  the  fulphate  of  lime,  which  is 
fufpended  by  the  afliftance  of  the  citric  acid,  to  fall  down. 

The  citric  acid  which  I  have  prepared  is  the  produd  of  feveral  chefts  of  lemons.  Thfc 
mafs  of  calcareous  citrate  which  was  decompofed  was  fomewhat  confiderable,  and  the  ope- 
ration was  performed  in  large  ftone-ware  veflels.  The  fulphate  of  lime  obtained  by  the  de- 
compofition  of  the  calcareous  citrate  was  well  wafhed  in  tubs  of  white  wood.  The  dif- 
ferent liquors  were  united  together  for  evaporation  in  ftone-ware  veflels,  at  the  tem- 
perature of  boiling  water.  They  were  clear,  light-yellow,  and  contained  an  excefs  of  ful- 
j)huric  acid. 

As  foon  as  the  liquors  were  fufficiently  concentrated  by  evaporation,  the  fulphuric  acid 
exerted  its  aftion,  and  the  yellow  colour  became  brown,  and  even  blackifli  at  the  end  of 

•  Read  to  the  National  Inftitute  of  France,  and  copied  in  the  Journal  de  Phyfique,  publiflied  to  fupply  the 
iefeft  of  the  numberfot  September  1794. 

G%  Out 


44  Purificaikn  of  tht  Acid  ef  Lemons. 

the  evaporation.     The  mafs  of  cryftals  which  was  taken  out,  after  cooling  and  three  days 
Tcpofe,  was  confiderable  and  black. 

I  fufFered  this  faline  mafs  to  drain  in  oCer  balkets,  while  the  evaporation  and  cryftalliza- 
tion  of  the  remaining  fluid  were  performed.  When  this  firft  operation  was  ended,  the  whole 
of  the  faline  mafs  was  re-diflblved  in  a  fufficient  quantity  of  cold  water,  and  filtered  through 
ftrainers  of  linen,  covered  with  filtering  paper. 

The  folution  which  paflTed  the  filter  was  clear,  but  of  a  dirty  brown,  and  the  greateft 
quantity  of  the  matter  which  had  blackened  the  cryftals  remained  behind.  This  was  again 
evaporated,  left  to  cryftallize,  and  in  this  manner  exhaufted  of  the  citric  acid.  The 
cryftals  were  now'  yellow,  and  more  regularly  figured.  By  a  third  folution,  filtration, 
and  evaporation,  the  cryftals  were  again  obtained  white,  regular,  and  of  the  greatefl 
purity.  The  black  matter  depofited  on  the  filter  was  fo  trifling  that  it  formed  a  very 
flight  covering. 

Scheele,  who  was  content  with  having  proved  the  poffibility  of  obtaining  this  vegetable 
acid  io  a  concrete  ftate,  could  not  determine  its  natural  form,  becaufe  he  operated  on  fuch 
fmall  quantities. 

My  refults  afforded  cryftals  as  large  as  are  ufually  obtained  from  the  ordinary  procefles 
of  faline  folution,  and  as  %afily  to  be  defcribed.  They  prefent,  on  fimple  infpeftion, 
rhomboidal  prifms,  the  fides  of  which  are  inclined  to  each  other  in  angles  of  about  120 
and  60  degrees,  terminated  at  each  end  by  four  trapezoidal  faces  which  include  the  folid 
angles. 

I  have  before  remarked,  that  Scheele  had  obferved,  as  one  of  the  conditions  eflentlal  to 
the  ready  cryftallization  of  the  citric  acid,  to  add  a  fmall  quantity  of  fulphuric  acid  in  ex- 
cefs  beyond  the  exa£l  quantity  neceflary  to  decompofe  the  calcareous  citrate.  The  remark 
of  this  chemift  not  being  followed  by  any  explanation,  my  trials  in  the  large  way  have 
proved  the  great  difcernmenc  of  the  chemift  of  Gottingen  ;  and  that,  if  he  had  operated 
on  a  quantity  of  lemon  juice  equal  to  that  which  I  purified,  he  would  have  afcertained 
the  reafons  why  this  excefa  of  acid  was  found  to  be  necelTary  in  his  more  confined  expe- 
riments. 

Having  afcertained  that  the  black  matter  remaining  on  the  filters  in  this  procefs  is  char- 
coal, it  follows  that  it  could  not  have  been  afibrded  but  at  the  expence  of  a  confiderable 
portion  of  the  mucilaginous  matter  of  the  lemon  juice,  which  the  citric  acid  had  carried 
with  it  in  its  combination  with  the  bafe  of  the  calcareous  carbonate ;  and  that  afterwards 
when  the  citrate  is  decompofed,  the  excefs  of  fulphuric  acid  is  required  to  decompofe  this 
mucilage,  and  precipitate  the  carbone,  as  foon  as  the  fluid  begins  to  be  condenfed  by  eva- 
poration. The  ingenious  experiments  of  Fourcroy  and  Vauquelin  prove  the  nature  of  the 
aition  of  fulphuric  acid  on  vegetable  matter,  and  ftrongly  confirm  my  inductions  *. 

Lemon 

*  Forthcfe  important  txperiments  fee  Philof.  Journal  I.  3S5.— In  order  to  (hew  that  mucilage  enters  into  the 
citrate  of  lime,  and  that  it  is  docompofed  by  fulphuric  acid,  itfeems  neceflary  to  make  the  experiment  with  only 
a  very  tninure  excefs  of  the  latter.  Scheele  thought  the  acid  (Eflfays,  p.  361.)  in  the  citrate  to  be  pure,  aud 
he  required  an  excefs  of  fulphuric  acid  to  be  added  to  infure  the  faturation  of  the  whole  of  the  lime.  I  would 
propofe  to  the  confideration  of  the  Jeamed  author  of  thii  paper,  to  afcertain  whether  it  be  not  a  ponion  of  the 
acid  itfelf  wliich  is  altered  and  made  to  dcpofit  carbone.    If  fo,  the  lefs  the  furplus  of  fulphuric  acid  the  better : 

4  b»t. 


Purification  of  the  Acid  if  Lemons,  45 

Lemon  juice  feparated  from  all  the  mucous  matter  which  falls  down  by  cxpofure  to  the 
contaft  of  the  air  for  a  few  hours,  that  is  to  fay,  fuch  as  it  ought  to  be  for  ufe  in  medicine 
or  the  arts,  marks  five  degrees  of  denfity  by  the  areometer  for  falts  of  Baume  (fpeclfic  gra- 
vity 1.034).  One  hundred  pounds  of  this  juice  require  for  faturation  fix  pounds  four 
ounces  of  calcareous  carbonate.  The  citrate  of  lime,  after  being  well  waflied  and  dried, 
weighs  twenty  pounds. 

One  pound  of  pure  cryftallized  acid  of  lemons  diflblved  in  a  fufficient  quantity  of  water, 
demands  one  pound  of  carbonate  of  lime  for  its  faturation.  In  this  experiment  the  weight 
of  calcareous  citrate  has  diminifhed  the  mafs  rather  more  than  one-fourth  part,  inftead  of 
increafing  it  upwards  of  two-thirds,  as  in  the  foregoing  combination.  Whence  it  may  be 
concluded,  that  one  hundred  pounds  of  lemon  juice  faithfully  prepared,  and  of  the  ftrength 
of  five  degrees  by  Baume's  areometer  for  falts,  contain  fix,  pounds  four  ounces  of  pure 
concrete  acid.  This  ferves  to  explain  two  phenemena }  that  is  to  fay,  the  increafe  of  i  jibs. 
20Z.  in  the  calcareous  citrate  from  lemon  juice,  and  the  prefence  of  mucilaginous  matter 
diflblved  in  that  liquid,  which  enters  into  the  combination  of  the  calcareous  citrate,  and  is 
afterwards  decompofed  by  the  excefs  of  fulphuric  acid  neceflary  to  be  added  when  that 
citrate  is  decompofed. 

One  ounce  of  diftilled  water  diflblves  an  ounce  and  two  drams  of  citric  acid,  and  pro- 
duces 13  degree*  (K»)  of  cold  by  the  folution.  A  like  quantity  of  diftilled  water  diflolves 
twice  its  weight  of  this  acid,  when  it  is  heated  to  80  degrees,  or  the  boiling  temperature. 
One  hundred  parts  of  citric  acid  diflblved  in  a  fuflicient  quantity  of  diftilled  water,  boiling 
hot,  diflTolve  50  parts  of  calcareous  citrate. 

A  lemonade  of  the  moft  agreeable  tafte  and  appearance  may  be  had  by  diflblving  40 
grains  of  citric  acid  in  a  pint  of  water,  with  the  addition  of  a  fufficient  quantity  of  pure 
fugar.  It  may  be  rendered  fragrant  by  diflblving  a  fmall  quantity  of  oleo-faccharum,  pre- 
pared by  rubbing  a  lemon  on  a  lump  of  fugar.  The  fugar  imbibes  the  volatile  oil  of  the 
lemon,  and  renders  it  foluble.  It  is  eafy  by  this  means  to  preferve  the  whole  of  the  vo- 
latile oil  of  a  number  of  lemons.  The  oleo-faccharum  thus  obtained  may  be  mixed  in  a 
mortar  with  a  fufficient  quantity  of  fugar.  The  mixture  is  then  to  be.  dried  by  a  gentle 
heat,  and  preferved  in  well  clofed  glafs  veflels.  This  method  of  procuring  the  flavour  of 
lemons  at  all  times  is  preferable  to  employing  the  volatile  oil  obtained  by  diftillation.  The 
aftion  of  fire  communicates  to  this  laft  an  acrid  flavour,  eafily  diftinguiffied  by  a  delicate 
tafte. 

I  {hall  finlfli  my  obfervations  by  enumerating  fomc  of  the  chara£lers  of  this  acid,  when  ^ 
mixed  with  different  earthy  and  metallic  folutions. , 

Solutions  of  the  acetites  of  magnefia,  lime,  alumine,  of  the  muriates  of  barytes,  lime, 
alumine,  and  magnefia,  and  of  the  nitrates  and  fulphates  of  thefe  fame  fubftances,  ,do  not . 
undergo  any  change  by  the  prefence  of  the  citric  acid. 

The  muriates  and  nitrates  of  zinc,  the  fulphate,  muriate,  nitratCj  and^acetite  of  copper, 

but,  on  the  other  hand,  if  his  inference  be  corrcft,  the  furplus  muft  he  a  definite  quantity,  namely,  fufficient  . 
to  deftroy  the  mucilage.     The  difference  of  weight  in  the  citrates  fermed  by  tlie  crude  and  the  purified  acids 
with  equal  dofes  of  lime,  as  mentioned  in  a  fubfequent  parsgraph,  may  arife  either  from  the  prefence  of  mu- 
cilage in  the  former  acid,  or  a  change  of  affinity  for  lime  produced  by  the  re-aftion  of  the  excefs  of  fulphuric 
»cid  on  the  latter  :  but  experiment  mull  determine  which.    M . 

iind 


46  Vfeful  Nottcet. 

and  the  nitrate  of  lead,  are  not  dccompofed,  but  the  acetite  of  lead  is  Immediately  decom- 
pofed  and  precipitated  in  a  white  powder.  The  nitrate  and  acetite  of  mercury  are  alfo  dc- 
compofed, and  the  mercurial  citrate  which  falls  down  is  a  flaky  fait,  of  a  brick-duft  co- 
lour, more  or  lefs  red.  The  citric  acid  gives  a  green  tinge  to  the  folution  of  the  acetite  and 
fulphate  of  iron. 

The  quantity  of  citric  acid  which  I  obtained  being  conGderable,  I  intend  hereafter  to 
give  an  account  of  the  phenomena  it  exhibits  in  its  different  combinations. 


XIV. 


Ufeful  Notices  refpeHing  various  ObjeHs. — Governor  for  regulating   the    Motions  of  Steam' 

Engines. — Amelioration  of  Oil. 


T. 


Governor  for  regulating  the  Motions  ofSteam-Engines. 


H  E  apparatus  mentioned  page  424  of  the  prefcnt  work  by  the  name  of  a  Governor,  is 
there  fuppofed  to  be  the  invention  of  Mr.  "Watt.     My  fuppofition  was  grounded  upon  no 

other  fa<5t  than  that  of  having  feen  it  in  his  engines.     It  was  invented  by Bunce,  Efq. 

of  the  Admiralty,  who  applied  it  to  a  crane  feveral  years  ago,  the  conftru£lion  of  which 
was  communicated  to  the  Society  of  Arts,  foon  after  which  period  it  was  adopted  in  fteam- 
engines.  I  cannot  now  refer  to  the  volume,  as  I  do  not  pofTefs  the  fet.  But  I  had  the  in- 
formation from  the  inventor  himfelf. 

■2.    Amelioration  of  Oil. 

EVERY  one  who  has  occafion  to  ufe  lamps  muft  be  fcnfible  that  the  colour  of  the  lights 
as  well  as  the  quantity  and  kind  of  difagrceable  vapour  emitted  from  the  flame,  depends 
greatly  on  the  quality  of  the  oil.  When  oil  is  kept  in  an  open  veflel,  it  gradually  becomes 
more  and  more  oxygenated,  and  at  the  fame  time  lefs  fluid.  For  both  thefe  reafons  it  is 
lefs  fit  for  ufe.  It  is  lefs  combuftible,  and  lefs  adapted  to  pafs  between  the  fibres  of  the 
wick.  Thefe  obfervations  point  out  the  expediency  of  keeping  oil  in  well-clofed  veflels. 
The  fluidity  of  whale-oil,  and  the  facility  of  its  combuftion,  may  be  confiderably  augmented 
by  an  addition  of  cold-drawn  linfeed  oil. 

It  is  well  known  that  oil  may  be  rendered  purer  by  agitation  with  water,  more  particu- 
larly with  the  addition  of  an  acid.  The.effeft  of  this  procefs  is  dated  to  be,  that  it  carries 
off  a  portion  of  mucilage,  which  is  not  adapted  to  anfwer  the  purpofes  to  which  oil  is  applied. 
It  may  eafily  be  imagined,  however,  that  oil  thus  treated  will  retain  a  portion  of  aqueous  or  fa- 
line  matter,  which  may  render  it  unfit  to  be  applied  to  the  moving  parts  of  inftruments  for 
the  purpofe  of  diminilhing  fridlion.  Some  clock  and  watch  makers  expofe  olive-oil  to  the 
atmofphere  in  frofty  weather ;  and  feleft  that  portion  which  they  find  to  continue  fluid 
after  a  confiderable  part  is  frozen.  This  proceeding  is  grounded  on  the  fuppofition,  that 
the  oil  may  confift  of  two  different  fluids,  one  of  which  is  fuppofed  to  congeal  in  a  lefs  heat 
than  the  other ;  and  that  this  congelation  is  the  principal  evil  which  happens  to  the  oil  ia 
iime-pleces.    It  does  not  feem  probable  that  either  of  thefe  fuppofitions  arc  well  feanded. 

FfiT 


Purification  of  Oil.-—Ne'W  Puhlicatitn,  47 

For  the  whole  of  the  oil  will  freeze,  if  time  be  allowed  ;  and  the  thickening  of  this  fluid 
appears  to  be  produced  by  chemical  change,  and  not  by  mere  cooling.  Mathematical  inftru- 
ment-makers,  diredted,  as  I  imagine,  by  experience  only,  find  that  oil  is  greatly  improved 
by  expofure  to  light,  which  it  is  aflerted  caufes  it  to  depofit  mucilage.  A  very  exquifite  re- 
gulator having  the  dead-beat  fcapement  of  Graham,  which  requires  oil  on  the  pallets,  was 
found  to  go  much  more  fteadily  when  this  oil  was  ufedj  inftead  of  the  oil  commonly  ap- 
plied to  fuch  inftruments. 

Moft  of  the  fa£ls  here  dated  refpe£ting  oil  were  communicated  to  me  by  an  intelligent 
cultivator  of  the  fciences,.whofe  name  I  forbear  to  add  becaufe  I  negledled  to  aft  permif- 
fion  for  that  purpofe. 


NEW    PUBLICATION, 

Reports  of  the  late  Mr.  John  Smeaton,  F.  R.  S.  made  on  various  Occafions  in  the  Courfe 
of  his  Employment  as  an  Engineer.  Printed  for  a  Scleft  Committee  of  Civil  Engineers. 
Sold  by  Faden  in  London.  Quarto.  412  pages,  rather  clofely  printed,  with  a  Portrait 
of  the  Author,  and  2  plates. 

J.  HAT  Smeaton  was  a  man  of  flrong  natural  powers  and  great  induftry,  that  his  expe- 
rience and  obfervations  were  extenfive,  and  his  fuccefs  highly  to  the  credit  of  himfelf  and 
his  country,  are  too  well  known  to  be  infilled  upon.  This  firll  volume  of  his  Reports  is 
publilhed  at- the  expence  of  Sir  J.'Banks,  Capt.  J.  Huddart,  Wm.  Jeflbp,  Robert  Milne, 
and  John  Rennie,  Efqrs.  conditionally  that  the  profits  fliould  be  given  to  Mr.  Smeaton's  re- 
prefentatives.  If  this  liberal  effort,  by  which  the  natioa  is  benefited  by  fo  valuable  a  mafs 
of  pradlical  information,  fliould  be  attended  with  fuccefs,  another  volume  will  appear,  con- 
taining the  remainder  of  the  Profeffional  Reports  of  this  great  engineer.  I  fliall  take  the 
earliefl  opportunity  of  communicating  the  general  principles  ufed  and  adopted  by  Smeaton, 
in  a  paper  I  intend  to  draw  up  refpecting  the  relative  value  and  effedl  of  firft  movers,  and. 
other  elementary  objefts  of  daily  ufe  to  en^neers;  and.  in  the  mean  time  fliall  avail  myfelf 
of  the  Preface,  nearly  verbatim,  to  thefe  Reports,  to  give  fomc  account  of  the  Society  of> 
Civil  Engineers. 

The  origin  of  the  Society  of  Civil  Engineers  took  its  rife  from  the  following  circum- 
ftances  : — Before  or  about  the  year  1760,  a  new  sera  in  all  the  artsand  fciences,  learned  and 
polite,  commenced  in  this  country.  Every  thing  which  contributes  to  the  comfort,  the 
beauty,  and  the  profperity  of  a  country,  moved  forward  in  improvement  fo  rapidly  and 
fo  obvioufly  as  to  mark  that  period  with  particular  diftinftion. 

The  learned  Societies  extended  their  views,  their  labours,  and  their  obje(£ls  of  rcfearch. 
The  profeflbrs  of  the  polite  arts  affociated  together  for  the  firft  time  ;  and  they  now  enjoy 
aproteftion  favourable  to  improvement,  and  not  lefs  honourable  to  real  merit  than  to  the 
Public  and  the  Throne,  which  have  with  one  accord  promoted  their  profperity. 

Nor  have  thefe  exertions  failed  of  producing  the  adequate  effefts,  comparing  the  prefent 
with  the  pad  (late  of  things. 

Military  and  naval  eftablifliments  were  made  or  enlarged,  to  promote  and  extend  the 
true. knowledge  on  which  thefe  fciences  depend. 

1.  Tba. 


4?  Origin  njthe  Sofidy  of  Civil  Etigineers. 

The  navy  of  England  fails  now  uncontrouled  in  every  part  of  the  habitaWe  world,  and 
herfliips  of  war  defy  the  combinetl  power  of  all  other  maritime  nations. 

It  was  about  the  fame  period  that  manufa£tures  were  extended  on  a  new  plan,  by  the 
cnterprife,  the  capital,  and,  above  all,  by  the  fcience  of  men  of  deep  knowledge  and  perfe- 
vering  induftry  engaged  in  them. 

.  It  was  perceived  that  it  would  be  better  for  eftabliiliments  to  fct  down  on  new  fituations, 
bed  fuited  for  raw  materials  and  the  labour  of  patient  and  retired  induftry,  than  to  be 
plagued  with  the  miferable  little  politics  of  corporate  towns,  and  the  wages  of  their  extra- 
vagant workmen. 

This  produced  a  new  demand,  not  thought  of,  till  then,  in  this  country — internal  navi- 
gation. To  make  communications  from  fa£lory  to  fa£lory,  and  from  warehoufes  to  har- 
bours, as  well  as  to  carry  raw  materials  to  and  from  fuch  eftablifliments,  became  abfolutely 
neceflary.  Hence  arofe  thofe  wonderful  works,  not  of  pompous  and  ufelefs  magnificence, 
but  of  real  utility,  which  are  at  this  time  carrying  on  to  a  degree  of  extent  and  magnitude 
to  which  as  yet  there  is  no  appearance  of  limitation.   • 

The  ancient  harbours  of  this  ifland,  it  may  be  faid,  have  ever  been  neglefted,  confidering 
the  increafe  of  its  naval  power,  and  a  foreign  commerce  of  which  there  has  never  been  an 
example  in  the  hiftory  of  mankind.  The  fea-ports  were  (I  had  almoft  faid  are)  fuch  as  Na- 
ture formed,  and  Providence  has  bellowed  upon  us;  and  they  were  but  little  better  pre- 
vious to  that  period,  notwithftanding  fome  jetttes  and  piers  of  defence  ill-placed  had  been 
made  and  repeatedly  altered,  without  knowledge  and  judgment,  at  municipal,  not  govern- 
tnerit's  expence. 

This  general  fituation  of  things  gave  rife  to  a  new  profeffion  and  order  of  men,  called 
Civil  Engineers. 

In  all  the  polilhed  nations  of  Europe,  this  was  and  is  a  profeffion  of  itfelf.     Academies, 
-or  fome  parts  of  fuch  inftitutions,  were  appropriated  to  the  ftudy  of  it,  and  of  all  the  pre- 
paratory fciences  and  accomplilhments  neceflary  to  form   an  able  artift,  whofe  profeffion 
comprehends  the  variety  of  objeds  on  which  he  Is  employed,  and  of  which  the  prefent 
*  work  is  an  example,  and  a  proof. 

In  this  country,  however,  the  formation  of  fuch  artifts  has  been  left  to  chance  ;  and 
perfons  leaned  towards  the  public  call  of  employments  in  this  way,  as  their  natural  turn 
of  mind  took  a  bias.  There  were  no  public  eftablifliments,  except  common  fchools  for  the 
rudimental  knowledge  neceflary  to  all  arts,  naval,  military,  mechanical,  and  others. 

Civil  Engineers  are  a  felf-created  fet  of  men,  whofe  profeffion  owes  its  origin  not  to 
power  or  influence,  but  to  the  beft  of  all  proteftion,  the  encouragement  of  a  great  and 
powerful  nation ;  a  nation  become  fo  from  the  induftry  and  fteadinefs  of  its  manufafturing 
workmen,  and  their  fuperior  knowledge  in  practical  chemiftry,  mechanics,  natural  philo- 
fophy,  and  other  ufeful  accomplifliments. 

When  any  one  who  has  read  the  varied  particulars  of  this  publication,  (huts  and  lays 
it  down  for  contemplation,  he  will  reflect  on  the  natural  talents  and  fagacity  requifite  in 
that  mind  which  applies  to  fuch  a  profeffion  ;  on  the  patient  application  necefliary  to  ac- 
quire all  the  fubfervient  learning  previous  to  the  commencement  of  it ;  and  on  the  won- 
derful and  varied  powers  which  this  work  exhibits. 

{Tt  bt  toncluded  in  eur  fitxt.'] 


i  : -y/er //u-//?/i  o-u  '  Ar  u..  >  /,,    rUf^/(/;n!u^  /<iar/. 


Fhilosjoumal.  VolJUU.  t!umffp.48 . 


Fin.  2 . 


Bariow  Mttif> . 


'0^- 


mios.Jounial.Fol./I.J1.J .  i:i,-ui</ /j.  ^g . 


!    1 1 1. 1,1 1  ^    I    I , '   'T'TT^ 


:=i^ 


vs^nS-'i--^^^^^ 


z-^.^. 


::3  p 


Hmii'W  ^i%ilfy . 


JOUR   N   A   L 


OF 


NATURAL   PHILOSOPHY,   CHEMISTRY, 


ANO 


THE    ARTS. 


MAT    1798. 


ARTICLE    I. 

0«  the  maintaining  Power  in  Clocks  and  Watches. 
[Concluded  from  Page  419,  Vol.  I.] 

A  F  we  fuppofe  the  pendulum  of  a  clock  to  prcfcrve  its  length  invariable  *  during  all  the 
changes  of  temperature  to  which  it  is  expofed,  its  vibrations  will  meafurc  equal  portions 
of  time  fo  long  as  the  arc  of  vibration  continues  the  fame.  The  refiftance  of  the  air  and 
of  friflion  are  prevented,  by  the  maintaining  power,  from  dcftroying  the  vibration.  This 
power  may  be  applied  in  different  parts  of  the  arc  ;  and  may,  according  to  circumftances, 
render  the  time  of  vibration  either  {horter  or  longer,  or  it  may  fimply  maintain  it  without 
altering  the  time.  Whether  it  alter  the  whole  time  or  not  will  be  of  no  confequence  to 
the  performance  of  the  regulated  machine,  provided  the  effeft  of  the  maintaining  power 
is  itfelf  fubjedt  to  no  variation.  For  the  thing  required  is,  that  all  the  vibrations,  when 
once  brought  to  an  accurate  adjuftment,  fliould  continue  invariable.  It  is  therefore 
cflential  to  a  good  time-piece,  either,  i.  that  the  maintaining  power  itfelf  fliall  not  vary; 
or,  2..  that  it  (hould  be  applied  to  the  pendulum  or  balance  in  fuch  a  manner,  as  that  in 
all  variations  of  the  power  itfelf  the  time  of  vibration  may  continue  the  fame ;  or,  3.  that 
it  {hall  a£l  during  a  very  fmall  part  only  of  the  time  of  vibration,  in  order  that  the  cffcdl 
of  its  variations  may  be  lefs. 

*  Philofophical  Journal,  I,  page  58. 
Vol.  II.— Mat  17^8.  H  When 


I 


50  Maintaining  Power  ofTime-Plecef. 

When  the  train  of  wheels  in  a  clock  is  driven  by  a  weight,  the  more  immediate  caufe  of 
variation  confifts  in  the  periodical  irregularities  of  the  wheels,  the  pinions,  and  the  pivots, 
which  tranfmit  the  force  diminirtied  by  fridlion  and  oblique  aftions,  which  are  by  no  means- 
uniform  :  the  remoter  caufe  of  variation  confifts  in  the  oil  becoming  lefs  fluid  the  longer 
it  is  expofed  to  the  air.  But  when  a  train  is  driven  by  a  main  fpring,  the  caufes  of  irre- 
gularity are  greatly  increafed  by  the  diminution  of  force  in  the  fpring  as  it  runs  down,  and 
its  friction  in  the  box  ;  neither  of  which  are  fo  regular  as  to  admit  of  a  gotod  corre£llon 
from  the  fpiral  of  the  fuTee  round  which  the  chain,  that  a£i:s  upon  the  movement,  is  drawn. 
Perfeft  equality  of  the  maintaining  power  is  not  therefore  to  be  expected.  The  only  good 
expedient,  independent  of  the  efcapement,  appears  to  be  that  of  caufing  the  tr  in  to  go  by 
a  weight  or  fpring,  ferving  only  to  wind  up  the  laft  wheel  once  during  every  revolution, 
this  wheel  being  urged  by  an  appropriate  weight  or  fpring.  By  fuch  an  expedient  the 
clock  in  effect  becomes  a  time-piece  with  one  wheel  only,  in  which  the  irregularities  are 
minute,  and  their  recurrence  too  frequent  to  produce  any  confiderable  effedt  on  the  vi- 
brating part. 

When  the  irregularity  of  the  firfl  mover  is  propofed  to  be  remedied  by  its  mode  of  ap- 
plication, it  is  clear  that  it  muft  give  an  increafe  of  velocity  to  fuch  vibrations  as  are 
performed  through  longer  arcs,  in  order  that  the  times  may  continue  the  fame.  At- 
tempts have  been  made  to  accomplifli  this  obje£t,  by  giving  a  proper  figure  to  the  face 
of  the  pallets  of  the  efcapement ;  but  it  docs  not  appear  that  fuch  attempts  have  been  fuc- 
cefsful. 

The  third  method  of  equalizing  the  effe£ls  of  the  maintaining  power  with  regard  to  time 
18  founded  on  the  confideration,  that,  if  this  impulfe  eould  be  given  in  an  inftant,  the  whole 
of  the  vibration  would  be  free,  and  refemble  that  of  a  difengaged  pendulum  or  balance  ; 
and  if  the  forces,  by  which  the  vibrating  body  returns  to  its  point  of  quiefcence,  were  as 
the  fpaces  to  be  moved  through,  all  the  vibrations  would  be  performed  in  equal  times, 
whether  long  or  fliort,  or  whether  the  maintaining  power  were  greater  or  lefs.  This  dif- 
poCtion  is  peculiarly  adapted  to  the  balance.  For  it  is  pofFible  to  form  the  pendulum  fpring 
and  adapt  the  maintaining  power  to  fo  fmall  a  part  of  the  vibration,  that  the  times  ftiall  not 
perceptibly  vary,  even  when  the  power  itfclf  is  greatly  altered. 

Under  the  latter  points  of  view  the  efcapement  becomes  an  obje£t  of  great  importance, 
fince  on  this  the  manner  of  application  of  the  maintaining  power  muft  depend.  It  fcarcely 
fccms  ncceflary  to  fubdivide  or  arrange  the  principles  on  which  the  moft  eminent  artifts 
have  endeavoured  to  give  perfection  to  their  efcapements.  The  principles  will  perhaps 
beft  fliew  themfelves  in  the  form  of  remarks  upon  the  fevcral  conftruGions. 

One  of  the  moft  ancient  efcapements  is  that  which  is  at  prefent  applied  in  common  ] 
pocket  watches.     It  is  reprcfented  Fig.  i.  Pi.  IH.  and  is  beft  fuited  to  the  long  vibrations 
of  the  balance,  which  was  invented  earlier  than  the  pendulum  *.    A  B  denotes  the  rim  oF 

a  con- 

*  Doftor  Derham  on  Clockwork,  p.  86.  fourth  edition,  sffirms,  that  vibrations  are  no  where  mentioned 
or  alluded  to  in  the  clocks  defcribed  by  the  ancients  :  yet  we  learn  from  Vitruviiis  that  they  poffclTed  time- 
pieces with  wheel-work.  Falconet,  AcatUmie  tin  hfcriplicns  vol.  xx.  thinks  that  all  the  mechanical  time- 
pieces made  before  the  l6th  century  were  ckpfydra:  with  wheel-work  for  reckoning  the  fmaller  portions  of 

dcfceiit. 


Invention  of  the  Crown  Wheel  Efcnpemetit-,  is^c,  5! 

a  contrate  wheel  called  the  crown  wheel,  having  its  teeth  pointed  and  floped  on  one  fide 
only,  fo  that  the  points  advance  before  any  other  part  of  the  teeth  during  the  motion.  CD 
are  two  pallets,  or  flaps,  proceeding  downwards  from  the  verge  E  F.,  The  pallets  are 
nearly  at  right  angles  to  each  other ;  and  when  the  balance  F  G  fixed  to  the  verge  is  at 
reft,  the  pallets  remain  inclined  to  the  plane  of  the  wheel  in  an  angle  of  about  45  de- 
grees; but  when  it  is  made  to  vibrate,  one  of  the  pallets  is  brought  nearer  to  the  per- 
pendicular pofition,  while  the  other  becomes  more  nearly  parallel.  The  wheel  muft  be 
fuppofed  to  have  one  of  its  teeth  refting  againft  a  pallet  by  virtue  of  the  maintaining 
power.  This  tooth  will  flip  oft'  or  efcape  as  the  pallet  rifes  towards  the  horizontal  pofition, 
at  which  inflant  a  tooth  on  the  oppofite  Gde  of  the  wheel  will  flrike  againft  the  other  pallet 
which  is  down.  The  returning  vibration,  by  raifmg  this  laft  pallet,  will  fufFcr  that  tooth 
to  efcape,  and  another  tooth  will  apply  itfelf  to  the  firft-mentioned  pallet.  By  this  alterna- 
tion the  crown  wheel  will  advance  the  quantity  of  half  a  tooth  each  vibration,  and  the 
balance  or  pendulum  will  be  prevented  from  coming  to  reft,  becaufe  the  impulfe  pf  the 
teeth  againft  the  pallets  will  be  equal  to  the  refiftances  from  friftion  and  the  re-adtion  of  the 

air. 

On  this  efcapement  it  maybe  remarked,  that  the  pendulum  or  balance  is  conftantly  con- 
nected with,  and  influenced  by,  the  maintaining  power,  except  during  the  exceedingly  fmall 
time  of  the  drop  of  the  whefl  from  one  pallet  to  the  other  ;  on  which  account  the  meafure 
of  time  will  greatly  vary,  when  the  force  of  vibration  is  merely  equal,  or  not  much  greater 
than  the  maintaining  impulfe.  This  is  fliewn  in  a  ftriking  manner  by  urging  the  movement 
of  a  common  watch  by  means  of  the  key.  If  the  key  be  prelTed  in  the  ufual  diredlion 
of  winding  up,  the  beats  of  the  vibration  will  become  very  flow,  or  even  ftop;  and  if 
the  prefTure  be  made  in  the  oppofite  diredion,  the  vibrations  will  become  very  loud  and 
quick. 

dcfcent.  Profeflor  Vcnturi,  in  his  Effa'i  fvr  Ifs  Owjrages  PhyJico-MulbimMiquei  Je  Leonard  Je  Find,  page  18, 
bas  a  curious  note  on  this  fubjeft,  from  which  I  here  make  feme  extrafts.  The  common  efcapement  dc- 
fcribed  in  the  text  was  well  known  to  de  Vinci,  who  defcribes  an  inftrument  a£ling  by  an  efcapement  of  this 
kind,  fimilar,  as  he  fays,  to  the  verge  of  the  balance  in  watches,  which  he  does  not  feem  to  mention  as  a  new 
thing.  He  died  al)out  1513.  The  ifochponifm  of  the  pendulum  was  known  to  Galileo  in  i6oo,  who  before 
his  death,  namely  about  1633,  propofcd  to  apply  it  to  clocks.  The  aflual  application  by  Huyghens  was  made 
before  1658,  when  he  publiflied  his  Horologi um  ofciUatorium.  He  applied  it  by  means  of  the  common  efcape- 
ment already  in  ufe  with  the  balance,  and  ftill  retained  in  our  table  clocks.  San£lorius  had  made  the  fame 
application  near  forty  years  before  that  time,  as  appears  by  his  Cammenlarii  in  A-vicennam,  (qucji.  55)  printed 
in  1625,  in  which  feveral  inftruments  are  defcribcd  as  having  been  publicly  exhibited  and  explained  to  his 
auditors  at  his  Itftures  in  Padua  for  thirteen  years  previous  to  that  time. 

There  is  a  manufcript  (No.  7295)  in  the  National  Library  of  France,  written  about  the  middle  of  the  15th 
century  by  H.  Arnault,  Phyfician  to  the  Dukes  of  Burgundy,  who  died  in  1465.  This  author  defcribes  a 
planifphere  which  Jean  de  Fondeur  (Fuforis)  his  mafter  had  conftrafted  for  the  Duke,  and  which  Arnault 
himfelf  had  afterwards  repaired.  Whtnce  it  appears  that  the  inftrument  was  conftrufted  about  the  commence- 
iiient  of  the  ijth  century.  At  folio  c.<j  a  dtfign  is  feen  of  the  watch  which  gives  motion  to  the  planifphere.  It  rs 
nearly  the  moderm  watch.  The  balance  is  called  circulus  affixui  "virge  faletorum,  qui  cum  ea  de  -vi  movelur.  He 
calls  the  crown  wheel,  which  forms  the  common  efcapement  on  the  pallets  of  the  verge  of  the  balance,  by  the 
name  of  folietus.  At  folio  60  the  ftriking  part  is  defcribed,  where  we  have  the  terms  •voietus,  the  hrochif  ie- 
•uanles  malUum\  crux  media  inter  woiiimtntum  el  foineriam  ;  cavak  and  ciii-volci  for  cbeiiiUe.  M.  Vcnturi  thinki 
that  the  watches  of  Wallingfort  and  Dondi,  in  the  i4tli  teiftviry,  were  conftruftiJ  bn  thfc  principle  of- the 
balUncc.    Robert  Hooke  added  the  fpring  to  the  balance  in  the  year  1658. 

H  2  This 


5"2  Efcflpemetits  for  Pendulums, 

This  cfcapement  not  being  adapted  to  fuch  vibrations  as  are  performed  through  arcs  of 
a  few  degrees  only,  another  conftruftion  has  been  made  which  has  been  in  conftanc  ufc 
for  about  a  century  in  clocks,  with  a  ^ong  pendulum  beating  feconds.  Fig.  2.  A  B  repre- 
fents  a  vertical  wheel  called  the  fwing  wheel,  having  thirty  teeth.  CD  reprefents  a  pair 
of  pallets  connefted  together,  and  moveable  in  conjun£lion  with  the  pendulum  on  the  centre 
or  axis  F.  One  tooth  of  the  wheel  in  the  prefent  pofition  refts  on  the  inclined  furface  of 
the  inner  part  of  the  pallet  C,  upon  which  its  difpofition  to  Aide  tends  to  throw  the  point  of 
the  pallet  farther  from  the  centre  of  the  wheel,  and  confequently  affifts  the  vibration  in 
that  dire£lion.  While  the  pallet  C  moves  outwards  and  the  wheel  advances,  the  point  of 
the  pallet  D  of  courfe  approaches  towards  the  centre  in  the  opening  between  the  two 
neareft  teeth  ;  and  when  the  afting  tooth  of  the  wheel  flips  olF,  or  efcapes  from  the  pallet 
C,  another  tooth  on  the  oppofite  fide  immediately  falls  on  the  exterior  inclined  face  of  D, 
and  by  a  fmiilar  operation  tends  to  pufh  that  pallet  from  the  centre.  The  returning  vibra- 
tion is  thus  aflifted  by  the  wheel,  while  the  pallet  C  moves  towards  the  centre,  and  re- 
ceives the  fucceeding  tooth  of  the  wheel  after  the  efcape  from  the  point  of  D.  In  this 
manner  the  alternation  may  be  conceived  to  go  on  without  limit. 

'The  fame  obfervation  wliich  was  made  upon  the  efcapement  fig.  i.  is  applicable  alfo 
to  this  -,  namely,  that  the  vibrating  part  is  conftantly  under  the  influence  of  the  maintain- 
ing power,  except  during  the  interval  of  the  drop,  or  aftual  efcape  of  the  wheel  from  one 
pallet  to  the  other.  The  indireft  aftion  of  an  inclined  plane,  with  the  influence  of  oil 
which  it  neceflarily  requires,  may  alfo  be  mentioned  to  fl-.ew  that  this  efcapement  is  not 
equal  to  what  might  have  been  produced  by  a  flcilful  variation  of  the  other.  One  principal 
recommendation  of  this  efcapement  feems  to  have  been  the  facility  with  which  it  aflxirds 
an  index  for  feconds  in  the  face  of  the  clock.  Though  the  pendulum,  according  to  this 
conftruftion,  is  conftantly  conne£led  with  the  maintaining  power  in  a  clock,  yet  the  va- 
riations of  that  power  have  not  the  fame  mifchievous  efl"e£l:  as  in  a  watch,  becaufe  the 
momentum  of  the  pendulum,  compared  with  the  impulfe  of  the  maintaining  power,  is  pro- 
digioufly  greater  in  the  former  of  thefc  inftruments.  A  very  confiderable  change  in  the 
maintaining'  power  of  a  clock  with  a  long  pendulum,  will  not  caufe  a  greater  variatioa 
than  a  few  feconds  in  the  daily  rate. 

The  celebrated  George  Graham  improved  this  efcapement  very  much  by  taking  off  part 
of  the  Hope  fartheft  from  the  points  of  the  pallets  ;  infiead  of  which  part  he  formed  a  cir- 
cular or  cylindrical  face,  having  its  axis  in  the  centre  of  motion.  Pallets  of  this  kind  are 
feen  on  the  oppofite  fide  of  the  wheel  at  E  and  G,  having  H  for  their  centre  or  axis.  A 
tooth  of  the  wheel  is  feen  lefting  upon  the  circular  inner  furface  of  the  pallet  G,  which 
is  not  therefore  affefled  by  the  wheel,  excepting  fo  far  as  its  motion  arifing  from  any 
other  caufe  may  be.  aflx£led  by  the  fri£lion  of  the  tooth.  If  the  vibration  of  the  pendulum 
be  fuppofed  to  carry  G  outwards,  the  flope  furface  will  be  brought  to  the  point  of  the 
tooth,  which  will  Aide  along  it  and  urge  the  pallet  outwards  during  this  Aiding  aftion. 
When  the  tooth  has  fallen  from  the  point  of  this  pallet,  an  oppofite  tooth  will  be.  received 
on  the  circular  furface  of  E,  and  will  not  afi"e6l  the  vibration,  excepting  when  the  flope  fur- 
face of  E  is  carried  out  fo  as  to  fuffer  the  tooth  to  Aide  along  it.  In  the  two  former  efcape- 
Hients  there  is  always  a  certain  portion  of  vibration  takes  place  after  the  drop  which  drives 
the  pallets  back,  and  caufes  the  index  alfo  to  recede  through  a  fmall  arc.    This  has  been 

diftingulflicd 


DefcrtpttOM  and  Invention  of  the  koriztntal  Efcopcmettt.  53 

dift'inguifhed  by  the  name  of  a  recoil.  Other  conCderable  objcilions,  befides  that  of  the 
continued  a£tion  of  the  maintaining  power,  have  been  made  againft  efcapements  with  a 
r£Coil ;  but  it  would  lead  us  too  far  into  the  minute  departments  of  this  fubje£t  to  difcuf* 
them.  The  efcap«ment  of  Graham,  and  all  fuch  as  have  no  recoil,  have  been  called  dead 
beat  efcapements,  becaufe  the  index  for  feconds  falls  direclly  through  its  arc,  and  remains 
motionlefs  on  the  line  of  divifion  till  the  next  vibration.  It  may  be  obferved,  that  the 
maintaining  power  in  Graham's  efcapement  may  be  applied  during  a  fmall  portion  only  of 
the  vibration  ;  and  that  an  increafe  of  the  maintaining  power  tends  to  enlarge  the  arc  of 
vibration,  but  fcarcely  interferes  with  its  velocity. 

The  effeft  of  the  efcapement  which  has  been  called  horizontal  *,  becaufe  the  laft  wheel 
in  watches  of  this  conftruftion  has  its  plane  parallel  to  the  reft  of  the  fyftem,  is  fimilar  to 
that  of  the  dead  beat  efcapement  of  Graham.  In  fig.  3,  the  horizontal  wheel  is  feen  with 
twelve  teeth,  upon  each  of  which  is  fixed  a  fmall  wedge  fupported  above  the  plane  of  the 
wheel,  as  may  be  feen  at  the  letters  A  and  B.  On  the  verge  of  the  balance  there  is  fixed 
part  of  a  hollow  cylinder  of  fleel  or  other  hard  material,  the  imaginary  axis  of  which  pafles 
through  the  pivots  of  the  verge.  C  reprefents  this  cylindrical  piece,  into  which  the  wedge 
D  may  be  fuppofed  tohave  fallen.  While  the  vibration  caufes  the  cylindrical  piece  to  re« 
volve  in  the  diredlion  which  carries  its  anterior  edge  towards  the  axis  of  the  wheel,  the 
point  of  the  wedge  will  merely  rub  the  internal  furfacc,  and  no  otherwife  affedl  the  vibra- 
tion of  the  balance  than  by  retarding  its  motion.  But  when  the  return  of  the  vibration 
clears  the  cylinder  of  the  point  of  the  wedge  D,  the  wheel  will  advance,  and  the  flope  fur- 
face  of  the  wedge  afting  againft  the  edge  of  the  cylinder  will  affift  the  vibration  of  the  ba- 
lance. When  the  edge  of  the  cylinder  arrives  at  the  outer  point  of  the  wedge  D,  its  pofte- 
rior  edge  muft  arrive  at  the  pofition  denoted  by  the  dotted  lines  of  continuation  ;  immedi- 
ately after  which  the  wedge  or  tooth  E  will  arrive  at  the  pofition  e,  and  reft  on  the  outer 
furface  of  the  cylinder,  where  it  will  produce  no  other  efFed  than  that  of  retardation  from 
fridlion,  as  was  remarked  with  regard  to  the  wedge  D,  until  the  courfe  of  the  vibration 
ftiall  bring  the  pofterior  edge  of  the  cylinder  clear  of  the  point  of  the  wedge.  In  this  laft 
fituation,  the  wedge  will  aft  on  the  edge  of  the  cylinder,  and  affift  the  vibration,  as  in  the 
former  cafe,  until  that  edge  fliall  arrive  at  the  outer  or  pofterior  point  of  the  wedge  ;  imme- 
diately after  which  the  leading  point  will  fall  on  the  inner  furface  of  the  cylinder  in  the  firfl: 
pofition,  as  was  fhewn  in  the  wedge  D. 

"*  In  the  k\'mt\\voV\me  oi  Machines  et  Inventmns  approuvec!  par  I' Acai/emii;  RoyaU  cles  Sciences,  I  find » 
p.137,  that  the  Sietr  Bavfri,  a  French  clock-maker,  fettled  in  London,  contrived  ihe  horizontal  fcapement 
itt  1704.  He  applied  an  hollow  portion  of  a  cylinder  to  the  verge  of  the  balance,  the  edges  of  which  were 
thick  enough  to  afford  the  inclined  furfaccs  of  Graham's  psllets,  and  thel'e  were  aflei  upon  by  two  com- 
mon wheels  perfeflly  fimilar  and  fixed  on  the  fame  axis,  fo  that  the  teeth  of  one  corrcfponded  with  the  hollows 
oftheother.  In  the  fame  work,  p.  141,  the  Regie  artificielle  du  temps  of  Sully,  p.  14? — 2  5 1 ,  is  quoted  toi 
fliew  that  Sir  Ifaac  Newton  poffeiTed  one  of  thefe  watches,  marked  with  the  name  of  Baufrc.  Peter  le  Roy 
improved  this  fcapement  by  fubftituting  a  portion  of  a  cone  inftead  of  the  cylinder  (Machines  et  Inventions, 
'74i)>  ^'"'th  a  double  wheel,  the  axis  of  which  was  at  right  angles  to  the  verge.  And  M.  Gourdain,  in  the. 
fame  year  (p.  141  of  the  work  laft  quoted),  made  another  conftruftion,  in  which  a  flat  circular  piece  of  metal, 
out  of  which  a  portion  of  about  qo°  was  cut,  was  fubftituted  in  the  place  of  the  cylinder,  and  received  the  ac- 
ti»n  of  a  wheel  with  wtdge-teeth,  afting  alternately  in  oppofite  dircfticns  in  the  notch,  and  lefting  on  the  flat 
furface  of  the  metal  during  the  time  of  repofe.  The  fc^cment  defcribcd  iathe  text  appears  to  have  been  a  com- 
bioat.on  of  the  inventions  of  Baufrc  and  Gourdain. 

Horizonta' 


54'  Free  Efcapement  of  modern  Time- Pieces, 

Horiaontal  watches  were  greatly  efteemed  during  the  laft  thirty  years,  until  lately,  when 
they  gave  place  to  thofe  conftruflions  which  are  known  by  the  name  of  detached  or  free 
efcapements.  In  the  common  efcapement,  fig.  i,  an  increafe  of  the  maintaining  power  in- 
■creafes  the  recoil,  and  accelerates  the  vibrations;  but  with  the  horizontal  efcapement  there 
is  no  recoil ;  and  an  increafe  of  the  maintaining  power,  though  it  may  enlarge  the  arc  of  vi- 
bration, will  not  neceflarily  diminilh  or  alter  the  time.  It  is  accordingly  found,  that  the 
experiment  of  altering  the  maintaining  power  by  the  application  of  the  key,  does  not  alter 
the  rate  in  the  fame  perceptible  manner  as  in  common  watches.  Exceedingly  perfeft  time- 
pieces on  the  hori2ontal  principle,  with  a  compenfation  for  temperature  applied  to  the 
fpring,  were  made  about  fifteen  years  ago  by  Emery,  of  Charing-crofs,  and  other  artifts  ; 
but  I  am  informed  that  their  performance  became  fenfibly  lefs  accurate  after  a  few  years 
wear.  Whether  the  difficulty  of  execution,  or  the  badnefs  of  workman fliip  in  low-priced 
watches  of  this  kind,  or  whether  the  fubfequent  great  improvements  in  this  ufeful  engine, 
have  caufed  the  horizontal  principle  to  be  laid  aCde,  I  know  not  ;  but  1  believe  few  if  any 
watches  of  this  conftrudlion  are  at  prefent  made. 

The  dead  beat  efcapement  of  Graham,  and  the  horizontal  efcapement,  both  appear  to  be 
improvements  of  the  common  anchor  efcapement,  fig.  i.  which  by  thefe  expedients  is 
deprived  of  its  recoil,  but  flill  retains  the  wedge  adion,  which  has  much  friftion,  and  ne- 
ceflarily requires  oil.  The  quantity  of  diredl  pufli  in  the  efcapement  fig.  i,  which  re- 
quires no  oil  on  the  face  of  the  pallets,  appears  to  be  the  caufe  why  it  aiSls  fo  freely,  and 
is  fo  little  liable  to  injury  or  diforder.  I  wifti  it  were  lefs  diflicult  to  afcertain  the  invent- 
ors and  improvers  of  ufeful  contrivances.  But  in  proportion  to  the  utility  and  univerfal 
adoption  of  any  inftrument,  it  always  becomes  more  eafy  to  mention  it  by  a  fingle  term. 
Definitions,  defcriptions,  and  inventors'  names  naturally  become  difcarded  ;  and  from  this 
caufe  it  feems  as  if  a  moderate  or  a  fpeculative  invention  might  carry  the  name  of  its  in- 
ventor to  remote  ages,  while  the  great  benefa£lors  of  fociety  are  forgotten.  I  do  not 
know  who  firft  undertook  to  improve  efcapements  by  pallets  refembling  thofe  of  fig.  i.  in 
the  direfl  aftion  they  receive  ;  but  the  earlieft  contrivance  of  this  kind  I  have  met  with  is 
that  of  M.  Le  Roy  fils  aine,of  which  the  account  bears  date  Sept.6, 1748.  As  it  is  in  efFeiSl 
the  fame  efcapement  as  is  now  in  the  higheft  efleem  in  the  time-pieces  of  our  beft  artifts, 
I  (hall  here  dcfcribe  the  latter,  and  mention  the  particulars  of  that  of  M.  Le  Roy  in  a 
note. 

Fig.  3.  PI-  III-  reprcfents  the  free  efcapement  of  our  beft  portable  time-pieces.  Fig.  4. 
exhibits  the  efcapement  on  a  larger  fcale.  On  the  verge  of  the  balance  is  fixed  a  circular 
piece  of  fapphire,  or  hard  fteel,  EL,  out  of  which  a  fefloral  piece  is*  cut.  HG  is  a  ftraight 
fpring  fixed  near  its  extremity  H,  and  having  at  the  other  extremity  a  pin  G,  againft 
which  one  of  the  teeth  of  the  wheel  D  refts  when  the  train  is  at  reft.  This  fpring  has  a 
flight  tendency  towards  the  centre  of  the  wheel,  but  is  prevented  by  the  ftop  K  from 
throwing  the  pin  farther  inwards  than  juft  to  receive  the  point  of  the  tooth.  I  is  a  very 
{lender  fpring  fixed  at  the  end  I,  and  preffing  very  flightly  againft  the  pin  G,  in  a  direflion 
tending  to  throw  it  from  the  wheel  D,  but  which  on  account  of  the  greater  power  of  HG 
it  cannot  efFeft.  It  may  be  obferved  that  the  fpring  I  proceeds  a  little  beyond  the  pin  G.— 
F  is  a  lever  proceeding  from  the  verge  of  the  balance  diredly  oppofite  the  end  of  the 
fpring  I,  and  long  enough  to  ftrikc  it  in  its  vibration.    The  adion  is  as  follows : — From 

5  the 


invented  by  Le  Roy  of  Pari't,  et 

the  prcflure  of  the  main  fpring  the  wheel  (fig.  4)  is  urged  from  D  towards  F,  but  is  pre- 
vented from  moving  by  the  pinG.  Let  the  balance  be  made  to  vibrate,  and  the  lever  F  will 
move  through  t!ie  arc  Ff,  ftrike  the  inner  extremity  of  the  fpring  I,  and  difplace  the  pin  G. 
At  tills  inftant  the  face  E,  which  may  be  called  the  pallet,  will  have  arrived  at  the  pofition  e, 
againft  which  the  tooth  of  the  wheel  will  fall,  and  communicate  its  impulfe  through  about 
150  or  16°  of  the  vibration.  But  F  quits  the  fpring  1  fooner  than  the  wheel  quits  the 
pallet  E,  and  confequently  the  pin  G  will  have  returned  to  its  firft  ftation  before  the  wheel 
can  have  advanced  a  whole  tooth,  and  the  fpring  or  detent  HG  will  receive  the  wheel  as 
before,  immediately  after  its  efcape  from  the  pallet.  The  returning  vibration  of  the  ba- 
lance will  be  made  with  the  piece  EL  perfedlly  at  liberty  between  two  teeth  of  the  wheel, 
as  in  the  (ketch,  and  the  back  (Iroke  of  the  lever  F  againft  the  tender  fpring  I,  will  have  no 
efFeft  whatever  on  the  pin  G ;  this  fpring  being  like  the  batk  fpring  of  the  jacks  of  the  harp- 
fichord,  aftive  in  one  direcSlion  only.  The  third  vibration  of  the  balance  will  unlock  the 
detent  as  before  ;  the  impulfe  will  again  be  given,  and  the  whole  procefs  will  be  repeated  j 
and  in  this  manner,  the  balance,  though  it  may  vibrate  through  the  greateft  part  of  the 
entire  circle,  will  be  entirely  free  of  the  works,  except  during  the  very  fmali  time  of  the 
drop  of  the  wheel*. 

It  is  hardly  neceflary  to  make  any  remark  on  this  efcapement.  It  requires  little  or  no 
oil ;  and  when  all  the  parts,  particularly  the  pendulum  fpring,  are  duly  adjufted,  it  is  found 
that  a  very  great  variation  in  the  firft  mover  will  remarkably  alter  the  arc  of  vibration  with- 
out affe£ling  the  rate.  The  piece  EL  might  have  confifted  of  a  fingle  pallet  or  arm,  inftead 
of  a  portion  of  a  circle  or  cylinder  ;  but  fuch  a  piece  would  have  been  rather  lefs  conve- 
nient to  make  in  fapphire,  or  ruby,  as  in  the  beft  time-pieces,  and  would  alfo  have  been 
lefsufeful.  For  if  by  any  accident  or  (hock  the  pin  G  fhould  be  difplaced  for  an  inft^it, 
the  wheel  D  will  not  run  down,  bccaufe  it  will  be  caught  upon  the  circular  furface  of  EL. 

•The  cchappement  a  detente  of  Le  Roy  (Recueil  cfes  Machines,  &c.  VII.  385)  was  different  from  the  above 
defcribed  in  feveral  particulars  not  effemial  to  the  general  principle.  i.The  wheel  was  contrate,  and  in  the 
drawing  has  44.  thin  teeth.  2.  The  face  E  was  afforded  by  an  aftual  pallet  concave  towards  the  tooth. 
3.  The  detent  was  forked,  and  moved  on  pivots  at  the  angular  point.  One  leg  prefcnted  a  flop  to  one  of  the 
teeth  of  the  wheel,  while  the  other  leg  refted  againft  the  periphery  of  a  femi-cylinder  upon  the  verge  of  the 
balance.  The  detent  was  kept  to  this  pofition  by  a  tender  back  fpring.  4,  In  the  aftual  performance  the 
vibration  of  the  balance  carried  the  femi-cylinder  clear  of  the  leg  of  the  detent,  which  confequently  would 
have  quitted  the  wheel,,  if  the  back  fpring  had  been  ftrong  enough.  Immediately  after  the  arrival  at  this  no- 
Ction,  the  pallet  ftruck  a  tooth  of  the  wheel,  made  it  recoil,  and  delivered  the  detent,  which  flew  inwardj 
againft  the  radius  of  the  femi-cylinder.  The  wheel  being  thus  fet  at  liberty,  was  driven  back  through  an 
angle  of  near  20',  as  I  eflimate  from  the  drawing,  and  then  in  its  return  followed  the  balance  through  about  60"" 
or  70",  during  which  period  the  femi-cylinder  recovered  the  pofition  requifite  to  throw  the  detent  in  the  way  of 
the  fucceeding  tooth,  and  retain  the  wheel,  while  the  balance  continued  its  vibration,  difengaged  from  every  ac- 
tion but  that  of  the  rub  of  the  femi-cylinder  againft  the  tail  of  the  detent.  The  judicious  mechanic  will  per- 
ceive that  the  difpofuion  of  the  parts  in  the  efcapement  fig.  4.  are  much  for  the  better.  For  (a)  the  flexures- 
of  fprings  afford  a  lefs  variable  dedu£%ion  from  the  moving  force,  than  the  fridlions  of  furfaces  in  the  pivots  of 
Le  Roy's  detent,  and  his  ftmi-cylinder.  (b)  The  force  loft  in  the  recoil  is  greater  and  more  variable  than  that 
employed  againft  the  fpiing  I  in  fig.  4.  (c)The  balance  is  perfeftly  difengaged  for  a  much  larger  portion  of  both 
vibrations  in  the  modern,  than  in  the  original  efcapement,  and  (d)  the  fmall  number  of  teettuin  the  wheel  D' 
affords  an  advantage  in  regulating  the  figure  aod  C0iita£b  of  the  pacts. 

It 


«6  I'ree  EfcapetnentS.  >  ' 

It  is  indeed  very  eafy  to  obferve,  that  the  piece  EL  would  operate  without  the  detent, 
though  with  much  fridion  during  the  time  of  repofe.  The  tooth  of  the  wheel  would  in  that 
cafe  reft  upon  its  circular  face. 

This  efcapement  is  better  calculated  for  a  long  than  a  fliort  vibration.  I  have  feen  it 
adapted  to  an  half  feconds  pendulum  clock,  in  the  form  delineated  in  fig.  6,  PI.  III.  It 
kept  up  a  vibration  of  8°  with  a  very  heavy  pendulum,  and  no  great  maintaining  weight, 
but  I  was  not  informed  of  the  quantities  of  thefe  weights.  The  part  ABDC  is  fixed  to  the 
pendulum  rod.  BC  is  a  lever  moveable  on  the  joint  B,  but  not  capable  of  falling  below  its 
horizontal  pofition.  It  terminates  in  a  claw  at  C.  At  D  is  a  pallet  of  agate  or  hard  ftone, 
having  a  flat  poliflied  face.  F  G  H  I  is  a  detent  moveable  on  the  centre  H,  but  kept  in 
its  pofition  againft  the  pin  or  flop  K,  by  means  of  the  counterpoife  G.  As  it  is  now  repre- 
fented,  a  tooth  I  of  the  wheel  bears  againft  the  end  of  the  lower  arm  or  branch.  Suppofc 
the  pendulum  to  be  made  to  vibrate,  and  it  will  pafs  clear  of  the  teeth  I L  ;  but  when  the 
claw  C  ftrikes  againft  the  upper  end  F  of  the  detent,  the  flope  furface  of  thofe  extremities 
will  caufe  the  lever  B  C  to  rife,  and  the  claw  in  its  return  will  draw  F  towards  the  wheel, 
and  confequently  difengage  I.  The  tooth  E  will  therefore  fall  on  the  pallet  D,  and  impell 
the  pendulum  in  its  vibration  ;  but  before  it  quits  the  pallet  the  claw  C  will  be  drawn  away 
from  F,  and  the  counterweight  G  will  reftore  the  original  pofition  of  the  wheel,  which 
will  receive  and  hold  the  tooth  M  during  the  whole  of  the  vibration  made  in  the  direftion 
BC.  The  next  vibration  in  the  oppofite  diredtion  will  difplace  the  detent  as  before,  and 
by  thefe  alternations  the  motions  will  continue  fo  long  as  the  maintaining  power  continues 
to  aft. 

In  the  two  laft  efcapements  we  have  feen  the  variable  efFe£ls  of  the  maintaining  power 
ali^ft  entirely  removed,  as  far  as  can  be  pradically  difcerned.  Fig.  7.  *  exhibits  the 
efcapement  of  Mudge,  in  which  the  balance  is  perfe<31y  detached  from  the  train  of  wheels, 
except  during  the  extremely  (hort  interval  of  ftriking  out  the  parts  which  ferve  the  purpofe 
of  detents.  O  N  E  B  Q_  is  the  circumference  of  the  balance;  vibrating  by  the  a£lion  of  a 
fpiral  fpring  as  ufual  on  its  axis  C  A  D  H  paflfmg  through  the  centre  C :  the  axis  is 
bended  into  a  crank,  A  X  Y  D,  to  make  room  for  the  other  work.  L  M,  Z  W,  are  two 
rods  fixed  to  the  crank  at  the  points  L  and  Z,  parallel  to  X  Y.  c  d  e  f  r  s  are  fixed  parts  of 
the  machine.  T  R  is  an  axis  concentric  with  that  of  the  balance,  and  carrying  an  arm 
G  o  nearly  at  right  angles  to  it,  and  a  fmall  auxiliary  fpring  u,  which  is  wound  up  when- 
ever the  arm  G  o  is  moved  in  the  direftion  oh.  p  is  a  curved  pallet  fixed  to  the  axis  T  R, 
which  receives  the  tooth  of  the  balance  wheel  near  the  axis.  The  tooth,  proceeding  along 
the  curved  furface,  by  the  force  of  the  main  fpring  turns  the  axis  and  its  arm  Go,. and 
winds  up  the  fpring  u.  A  fmall  projeftion  at  the  extremity  of  the  curved  furface  of  the 
pallet  p  prevents  the  farther  progrefs  of  the  tooth,  when  the  arm  o  G  has  been  turned 
thfough  an  arc  oh,  of  about  27O;  and,  confequently,  the  fpring  u  has  been  wound  up 

through  the  fame  angle  or  arc,  0  Gh=  27°. F  S  is  another  axis  exaftly  Cmilar  to  TR. 

It  canics  its  arm  I  o,  and  fpring  v,  and  the  tooth  of  the  balance  wheel  1  m  winds  up  the 

•  From  Atwood's  lovcfiigations  for  determining  the  Times  of  Vibration  of  Watch  Balances.     Philof. 
Tranf.  1794. 

fpring 


Mudgis  Free  Efcnpemmt.  ma 

fpring  V,  by  a£ling  on  the  pallet  q,  and  is  detained  by  a  projc(flion,  after  liavlng  carried  it, 
through  an  angle  of  27°,  cxaiflly  as  in  the  former  cafe.  The  arcs  pafled  through  by  th? 
arms  G  o  and  I  o,  and  marked  in  the  figure,  are  alfo  denoted  by  the  fame  letters  on  the 
rim  of  the  balance. 

The  cffe£l  of  this  efcapement  may  be  thus  explained  :  Let  the  balance  be  in  the  qui- 
efcent  ftatc,  the  main  fpring  being  unwound,  and  the  branch  or  crank  in  the  pofition  re- 
prefented  in  the  figure.  If  the  qulefcent  points  of  the  auxiliary  fprings  coincide  with  that 
of  the  balance  fpring,  the  arm  Go  will  juft  touch  the  rod  LM,  and  in  like  manner  the 
arm  lo  will  juft  touch  the  rod  W  Z ;  the  two  arms  G  o  and  loin  this  pofition  are  pa- 
rallel to  the  line  CO.  -This  pofition  of  the  balance  and  auxiliary  fprings  remains  as  long 
as  the  main  fpring  of  the  machine  continues  unwound  ;  but  whenever  the  a£lion  of  the 
main  fpring  fets  the  balance  wheel  in  motion,  a  tootli  thereof  meeting  with  one  or  other 
of  the  pallets  p  or  q,  will  wind  up  one  of  the  auxiliary  fprings;  fuppofe  it  fliould  be  thfr 
Ipring  u.  The  arm  G  o  being  carried  into  the  pofition  G  h,  by  the  force  of  the  balance 
wheel  ading  on  the  pallet  p,  remains  in  that  pofition  as  long  as  the  tooth  of  the  balance 
wheel  continues  locked  by  the  prcjedion  at  the  extremity  of  the  pallet  p ;  and  the  balance 
itfelf  not  being  at  all  affeded  by  the  motiofi  of  the  arm  G  o,  nor  by  the  v/inding  up  of 
the  fpring  u,  remains  in  its  quiefcent  pofition  :  confequently  no  vibration  can  take  place, 
except  by  the  afiiftance  of  fome  external  force  to  fet  the  balance  in  m.otion.  Suppofe  an 
impulfe  to  be  given  fufficient  to  carry  it  through  the  femi-arc  OB,  which  is  about  i35« 
in  Mr.  Mudge's  conftrudion. 

The  balance,  during  this  motion,  carries  with  it  the  crank   AX  YD,  and  the  affixed 
rods  LM,  ZW.     When   the   balance  has  dcfcribed  an  angle  of  about  27"  =  the  angle 
o  C  h,  or  o  G  h,  the  rod  L  M  meets  with  tlie  arm  G  H,  and  by  turning  the  axis  T  R, 
and  the  pallet  p  in  the  diredlon  of  the  arc  oh,  releafes  the  tooth  of  the  balance  wheel 
from  the  projedion  at  the  extremity  of  the  pallet  p  :  the  balance  wheel  immediately  re- 
volves, and  the  lower  tooth  meeting  with  the  pallet  q,  winds  up   the   auxiliary  fpring  v, 
and  carries  the  arm  lo  with  a  circular  motion  through  the  angle  oik,   about  27^',  in 
which  pofition  the  arm   I  o  remains  as  long  as  the  tooth  of  the  balance  wheel  is  locked  by 
the  pallet  q.     While  the  fpring  v  is  winding  up  through  the  arc  ok,   the  balance  defcribes. 
the  remaining  part  of  the  femi-arc  hB,  and  during  this  motion  the  rod  LM  carries  round, 
the  arm  Gh,  caufing  it  to  defcribe  an  angle  hCB,  or  h  G  B,  which  is  meafured  by  the 
arc  h  B  =  108^.  When  the  balance  has  arrived  at  the  extremity  of  the  femi-arc  OB  =  135", 
the  auxiliary  fpring  u  will  have  been  wound  up  through  the   fame  angle  of  135",  that  is 
to  fay,  27°,  by  the  force  of  the  main  fpring  ading  on  the  pallet  p,  and  108°  by  the  ba- 
lance itfelf,  carrying  along  with  it  the  arm  Go,  or  G  h,  while  it  defcribes  the  arc  hB. , 
The  balance  therefore  returns  through  the  arc  B  O,  by  the  joint  action  of  the  balance 
fpring  and  the  auxiliary  fpring  u;  the  acceleration  of  both  fprings  ceafing  the  inftant  the 
balance  arrives  at  the  quiefcent  point  o.     When  the  balance  has  proceeded  in  its  vibration 
about  27°  beyond  the  point  O,  to  the  pofition  Ck,  the  rod  Z  W  meets  with  the  arm  Ik, 
and  by  carrying  it  forward  releafes  the  toothy  of  the  balance  wheel  from  the  pallet  q.     The 
balance  wheel  accordingly  revolves,  and  the  upper  tooth  meeting  with  the  pallet  p  winds 
up  the  auxiliary  fpring  u,  as  before.     Tlie  balance  with  the  crank  proceeding  to  defcribe 
Vol..  II.— May  1798.  1  the 


58  Invention  of  Efcapemtnii  ahfohtely  detached, 

the  remaining  femi-arc  k  E,  winds  up  the  fpring  v  through  the  further  angle  k  C  E  =  i  oS% 
and  returns  through  the  femi-arc  Eo,  by  the  joint  action  of  the  balance  fpring  and  the  auxi- 
liary fpring  V,  both  of  which  ceafe  to  accelerate?  the  balance  the  inftant  it  has  arrived  at  O. 
It  may  be  remarked,  in  this  curious  efcapement,  that  the  motion  of  the  balance  in  its 
femi-vibration  from  the  point  of  quiefcence  is  oppofed  through  an  arc  of  no  more  than 
108,  but  is  accelerated  in  its  return  through  the  whole  arc  of  135**,  and  that  the  dif- 
ference is  what  maintains  the  vibrations;  and  moreover,  that  the  force  from  the  wheel 
being  exerted  to  wind  up  each  auxiliary  fpring  during  the  time  it  is  totally  difcngaged  from 
the  balance,  this  laft  organ  cannot  be  affedted  by  its  irregularities,  except  fo  far  as  they 
may  render  it  more  difficult  to  difengage  the  rim  of  the  pallet  from  the  tooth.  The  balance 
defcribes  an  arc  of  about  8**  during  this  dlfengagement. 

From  a  paffage  in  a  pamphlet  of  Mr.  Mudge,  printed  in  1763,  which  I  have  feen,  and  is 
quoted  by  Count  Bruhl  *,  it  is  clearly  fliewn  that  that  artift  had  the  notion  of  the  principle 
bf  this  efcapement  in  his  mind  at  lead  thirty-five  years  ago.  From  the  fame  author's  de- 
,  fcription  it  appears  that  Mudge  had  organized  his  notions  in  the  prefent  form  before 
Auguft  I77i>  and  completed  his  firfl;  time-keeper  two  years  afterwards,  viz.  in  1773.  The 
performance  of  fuch  time-keepers  as  have  been  made  on  this  conftrudlion  has  proved  ex- 
cellent, but  not  fuperior,  as  1  am  informed,  to  fuch  as  have  been  made  with  the  efcape- 
ment No.  4.  There  are,  however,  many  circumflances  in  the  execution  of  the  workman- 
ship of  engines  of  this  delicate  nature,  which  mud  affedl  their  performance  whatever  may 
be  their  principle.  The  theory  of  Mudge's  efcapement  appears  to  be  more  perfeft  than 
that  of  the  other.  But  whether  its  fix  pivots  in  the  time-meafurer,  which  require  oil  and 
adjuftments  for  pofition  when  intended  for  the  pocket,  and  the  care  required  in  fettling 
the  points  of  quiefcence  in  the  three  diftindl:  fprings,  may  render  it  lefs  eafy  to  be  carried 
into  pra£lical  efFcwt,  will  be  in  a  great  meafure  an  obje£l;  of  opinion,  into  which  I  cannot 
now  enter. 

If  Mr.  Mudge  was  the  firfl  who  imagined  an  efcapement  abfolutely  detached,  I  think  it 
is  to  Mr.  Alexander  Gumming  that  we  are  indebted  for  the  firft  execution  of  a  like  con- 
trivance of  his  own.  This  well-known  artift,  in  the  year  1 763,  made  a  clock  for  the  king,  ia 
■which  there  was  no  fridion  during  the  repofe  of  the  movement,  and  the  maintaining 
power  was  applied  to  the  inclined  faces  of  a  pair  of  pallctsf ;  and  fome  time  previous  to 
J766,  he  improved  the  fame  fo  as  to  render  it  as  perfeflly  detached  as,  in  the  nature  of 
things,  an  efcapement  can  be.  As  this  has  been  fo  many  years  in  pofleflion  of  the  public, 
and  is,  as  I  think,  fimplified  in  the  fketch,  fig.  8, — I  flwll  only  fay  that  it  confiits  of  an  an- 
chor like  that  of  Graham,  but  having  a  detent  or  claw  at  each  end  in  (lead  of  pallets,  and 
two  feparate  pallets  prefled  (by  a  lever  and  weight  to  each)  tov/ards  the  centre  of  a  wheel 
like  AB,  fig.  2  ;  that  thefe  pallets  are  feverally  raifed  during  the  abfence  of  the  pendulum, 
which  difplaces  the  detent,  by  virtue  of  which,  when  the  pendulum  becomes  joined  with 
either,  the  maintaining  force  is  conftant  and  greater  in  the  defcent  than  in  the  afcent.  It 
feems  reafonable  to  infer,  that  Mr.  Mudge  mull  have  paid  great  attention  to  the  efcape- 

•  On  the  inveftigation  of  aftronomical  circles ;  (page  3,  of  regifter)  a  pamphlet  of  3  2  pages  oflavo,  printed  ia 
London  1794.  — 

f  Cumming's  Elements  of  Clock  and  Watch  Work,  p.  7S. 

ment 


Detached  Efcapements^  em 

mcnt  of  Cumnung  during  his  labours  for  organizing  his  own,  which  he  did  about  five 
years  afterwards. 

Fig.  8.  is  the  {ketch  of  an  adaptation  of  Mudge's  efcapement  to  a  clock.  LM  is  part  of 
the  periphery  of  the  wheel.  GA,  GB,  are  two  arms  feparately  moveable  on  the  fame 
axis,  and  terminating  in  the  pallets  A,  B.  Thefe  pallets  have  inclined  faces,  with  a  claw 
or  detent  at  the  lower  part  of  each.  GO,  lO  are  tails  proceeding  from  each  pallet-piece 
refpecSively,  and  the  dark  fpot  at  N  reprefents  a  pin  proceeding  from  the  pendulum  rod, 
and  capable  of  moving  either  of  the  tails  according  to  the  courfe  of  the  vibration.  The 
dotted  circles  u  and  v  reprefent  weights  which  are  fluck  upon  two  pins,  and  may  be 
changed  for  others,  greater  or  fmaller,  until  the  mod  fuitable  quantity  is  found.  Suppofe 
the  wheel  to  be  urged  from  L  towards  M,  and  the  pendulum  made  to  vibrate  by  external 
impulfc.  The  pin  N  proceeding  townrds  L  will  ftrike  the  tail  GO,  raife  the  pallet  A,  - 
and  fct  the  wheel  at  liberty  ;  which  Aiding  along  the  inner  furface  of  the  pallet  B,  will  raife. 
it,  and  flop  againfl:  the  claw  at  its  lower  end.  I O  will  confequentiy  be  carried  into  the  pofi- 
tion  IP ;  and  the  pallet  A  in  its  return  will  be  oppoHte  a  vacancy,  which  will  permit  the 
tail  GO  to  follow  the  pin  N  as  far  as  the  perpendicular  fituation.  The  pendulum  will 
therefore  be  afllfled  by  the  weight  u  through  a  longer  arc  in  its  defcent,  than  it  was  im« 
peded  by  it  in  its  afcent.  In  the  oppofite  femi-vibration  towards  M,  the  pendulum  will 
proceed  unoppofed  by  v,  while  it  pafles  through  the  angle  OIP,  when  it  will  raife  B,  and 
permit  the  wheel  to  elevate  the  pallet  A.  In  the  motion  on  this  fide  of  the  perpendicular, 
it  is  alfo  clear  that  the  defcent  will  be  more  aflifted  than  the  afcent  was  impeded. 
Whence  it  follows  that  the  clock  will  continue  to  go :  and  no  variation  of  the  force  of 
the  wheel  LM,  which  raifcs  the  pallets  in  the  abfence  of  the  pendulum,  will  affefl  the 
vibration,  except  fo  far  as  it  rhay  afford  a  variable  refiftance  at  the  detent  or  claw. 

From  obferving  that  the  detached  efcapemcnts  require  a  very  ftrong  firft  mover*,  and  that 
pendulum  clocks  meafure  time  with  great  accuracy  by  means  of  Graham's  dead  beat 
efcapement,  fig.  2,  notwithftanding  the  influence  of  oil  and  fridion  during  the  repofe  of 
the  movement,  I  was  induced  to  contrive  an  efcapement  which  fliould  be  as  free  as  the 
crown  wheel  efcapement,  but  have  no  recoil  or  aflion  during  the  time  of  reft,  nor  any 
tletent,  nor  require  oil  on  its  pallets.  I  made  a  drawing  at  the  beginning  of  the  year  1784, 
which  I  ftiowcd  to  various  mechanics  at  that  time.  It  has  fince  been  adapted  to  a  clock 
in  my  pofleffion,  and  has  been  going  very  freely  for  a  year  paft.  Fig.  9  is  a  (ketch  in 
which  GH  reprefents  a  fteel  wheel ;  D  and  E  are  pallets  of  agate,  with  flat  poliflied  faces. 
The  pallet  D  is  fixed  to  the  lever  DC,  which  is  confined  to  its  prefent  fituation  by  the 
loaded  branch  or  arm  CB  refling  on  the  flop  k.     The  lever  EC  is  alfo  kept  in  its  fituation 

•  A  pocket  time-piece  by  Brockb,iiik,  making  5  ribiationJ,  or  t|  beats  per  fecond,  the  radius  of  whofe 
balance  was  0.35  incli,  and  arc  dtfcribed  by  the  external  furface  of  the  expanf:on  pieces  0.45  inch  radius,  waj 
maintained  by  a  force  which,  on  trial  at  the  axis  of  the  fufee,  proved  equal  to  9I  oz.  troy,  paffing  through 
12  inches  in  14  hours.  Another,  of  the  fame  dimenfions  and  conftruftioD,  was  driven  by  j  i  J  oz.  with  the  fame 
daily  fall.  And  a  large  box  time-keeper  of  Arnold,  beating  half-feconds,  with  a  balance  of  two  radii,  each 
one  inch  long,  was  maintained  by  a  like  force  of  113  ouncei.  This  is  nearly  as  much  as  is  required  to  afford 
a  femi-vibration  of  31°  in  a  clock,  with  a  fcconds  pendulum  of  81b.  by  the  common  eight-day  train  with 
Graham's  efcapement  (fig.  4. ),  but  tb.rce  times  as  much  as  is  required  for  a  well  made  regulator.  A  common 
watch  with  a  balance  0.8  inch  diameter,  was  found  to  have  a  maintaining  power  of  5|o«,  f.Tlling  daily  through 
ix  iflchfrs 

la  hj 


60  Time-Pieca. -Engravings  on  Glafs, 

by  the  loaded  arm  CA  refling  upon  I.  A  pin  N  proceeds  from  the  pendulum  rod  to  its 
fituation  between  the  levers.  The  centre  of  motion  of  the  pendulum  is  in  the  continuation 
of  the  axis  of  the  pallets.  Suppofe  the  vibration  to  be  begun,  the  pin  N  in  its  progrefs 
will  lift  the  pallet  D  towards  L,  vi-hile  part  of  the  weight  B  will  be  fupported  by  the  tooth 
of  the  wheel  which  will  follow,  and  at  laft  efcape,  and  fuffer  the  oppofite  tooth  F  to  fall  on 
the  pallet  E.  But  in  its  return  or  defcent  the  pendulum  will  be  afted  on  by  the  whole 
weight  B,  and  confequently  its  vibration  v/ill  be  kept  up.  V/hen  the  pin  N  raifes  the 
pallet  E,  a  fimilar  effedl  will  take  place  on  the  fide  of  the  perpendicular  towards  M,  and 
thus  the  procefs  will  go  on  as  long  as  the  wheel  GH  retains  any  force. 

The  ancient  efcapement  with  the  crown  wheel,  verge,  and  pallets,  has  continued  in  ufe  for 
three  centuries,  becaufe  of  the  advantage  of  an  almoii  direft  pulh  againft  a  retiring  furface, 
which  enables  it  to  go  without  oil.  In  the  efcapement  laft  defcribed,  the  impulfe  being  more 
direifl  than  on  thofe  common  pallets,  it  goes  more  freely  without  oil ;  and  inllead  of  the  rc- 
adion  at  the  ends  of  the  vibrations,  the  pendulum  is  perfeftly  difengaged  during  the  whole 
time  of  repofe. 

From  this  general  view  of  the  principal  efcapements,  together  with  that  of  the  compen- 
fations  for  temperature  before  explained*,  the  philofophical  reader  may  form  fome  eftimate 
of  the  cautions  requifite  to  form  the  valuable  inftrument  by  which  a  meafure  of  time  is  af- 
forded. I  hope  it  fcarcely  need  be  added,  that  1  have  endeavoured  to  do  juftice  in  the 
hiftorical  narration,  and  ihall  be  happy  to  re£tify  any  miftakes,  if  better  information  (hould 
dete£l  them. 


11. 

Copy  of  a  Letter  from  Profejfor  WlLSON,of  GlafgoWf  on  the  Art  of  multiplying  Copies  of  engraved 

Plates  and  Stamps  in  relief  f. 

'    SiKj  Glafgow  College,  1^'^  March,  1798. 

1  DOUBT  not  but  you  will  have  the  goodnefs  readl«y  to  excufe  the  liberty  which  I  take 
upon  the  prefent  occafion  of  addreffing  you  by  a  printed  letter.  I  have  been  induced 
to  do  fo,  the  more  conveniently  to  communicate  to  you  fome  account  of  what  poffibly 
may  be  thought  entitled  to  the  appellation  of  a  new  art,  and  which,  for  particular 
rcafons,  it  has  been  thought  advifeable  to  make  more  or  lefs  generally  known,  even  at 
this  very  early  ftage  of  it. 

Some  years  ago,  upon  the  difcovery  of  the  fmgular  property  of  the  fluor  acid  in  cor- 
roding glafs,  when  it  was  fo  common  to  hand  about  bits  of  glafs-plate  frofted  over  by  this 
chemical  agent,  it  happened  to  ftrike  me  that  we  were  indulging  too  long  in  a  barren  ad- 
miration of  mere  novelty,  and  overlooking  a  matter  of  real  importance  to  which  it  evi- 
dently pointed.     The  general  effeft  of  what  then  fo  much  amufed  us,  when  the  plates. 

•  Philof.  Journal,  I.  p.  5*. 

f.J  firft  faw  this  letter  at  Sir  Jofcph  Banks's ;  bjt  having  fome  doubt  as  to  the  pro-n  icty  of  requefting  it  of 
hitnfor  publication,  1  fent  to  Mr.  Taflie,  who  favourcl  me  with  another  copy  for  that  cxprefs  purpofe.    N. 

were 


Prhtlfig  from  Glafs  Plates  hy  the  RslUng  Frvfs.  6 1 

were  viewed  by  tranfmitted  light,  fuggeftcd  the  pofTibility  of  formally  etching  with  deli- 
cacy and  perfettion  upon  glafs.  This  thought  no  fooner  occurred  than  it  challenged  fomc 
attention  in  confcquence  of  perceiving  that  glafs,  from  its  extreme  hardnefs  and  lubricity, 
would  preferve  the  execution  beftowed  upon  it  vaftly  longer  than  copper-plate,  were  it 
pofTible  to  introduce  its  fervices  at  the  rolling  prefs.  But  whilfl  harbouring  thefe  furmifes, 
the  extreme  fragility  of  glafs-plate,  contrafted  with  the  violent  preffure  it  muft  endure 
between  the  rollers,  had  well  nigh  made  me  rclinquifh  ihem  altogether.  It  often  happens, 
however,  that  things,  which  at  the  firlt  glance  feem  very  unattainable,  yield  to  a  little  re- 
flexion, when  they  are  fairly  fet  before  the  mind  in  the  light  of  valuable  defiderata. 

In  the  prefent  cafe  it  foon  became  very  evident,  that  the  thinned  and  fraileft  piece  of 
glafs-plate,  whether  ftraight  or  uneven,  could,  In  regard  to  the  flrongeft  preffure,  either 
general  or  topical,  be, rendered  as  robuft  and  as  rigid  as  iron  or  Heel.  The  expedient 
which  occurred  to  me  for  that  purpofe,  confided  in  nothing  but  joining  the  glafs-plate 
to  flat  pieces  of  tiiefe  metals,  of  confiderable  thickaefs,  by  an  intervetlinglamina  of  proper 
cement,  taking  care  that  it  affords  a  very  complete  cqntaCl. 

Agreeable  to  this  it  is  well  known,  that  fo  far  back  as  the  year  1791,  by  fortifying  glafs- 
plates  of  a  moderate  fize  in  this  way,  and  aiding  them  further  by  a  fimple  apparatus  on 
the  prefs  board,  I  fucceeded  completely  in  making  them  pafs  fafely' between  the  rollers, 
and  in  obtaining  many  impreffions,  fuch  as  the  fluor  acid  by  the  procefs  of  etching  could 
afford.  Upon  finding,  however,  that  the  beft  of  thefe  etchings  were  very  paltry,  and  ftiJl 
regarding  the  f^fe  paffage  of  the  glafs  between  the  rollers  as  an  interefting  experiment,  I 
was  infenfibly  led  to  confider,  whether  by  the  lapidary's  wheel,  or  by  any  other  poffible 
means  whatever,  we  could  fo  operate  upon  glafs-plate  as  to  render  it  a  produftive  fubject 
it  the  rolling  prefs.  This  ftep  appeared  of  fome  confequence,  as  being  all  that  was  now 
wanted  for  eflablifliing  an  improvement  not  deftitute  of  importance.  Not  long  after, 
certain  views  and  methods  occurred  to  me,  which  recently  have  been  prbfecuted  experi- 
mentally, and  which  raife  confiderable  expeflatiens  of  our  obtaining  the  maftery  over  aa 
art,  whereby  the  tame  fcratchings  of  the  fluor  acid  would  be  left  far  behind,,  and  tlie 
execution  and  fpirit  of  the  graver  itfelf  transferred  from  copper-plate  to  glafs-plate,  in 
infcriptions  of  all  kinds,  and  in^efigns  or  embcllifliments  of  any  fort,  efpeciaily  where 
hatching  conftitutes  the  manner;  and  all  this  with  the  further  advantage,  that  any 
number  of  fuch  glafs-plates  may  be  obtained  quite  alike,  as  being  derived  from  the  fame 
original  pattern. 

i  The  means  of  effecting  a  matter  of  fuch  apparent  difficulty,  like  moft  other  advances 
■in  the  Arts,  or  even  in  the  Sciences,  as  foon  as  ever  propounded,  will,  doubtlefs,  be 
thought  extremely  fimple  and  obvious.  But  whatever  fmall  portion  of  merit  may  be  al- 
lowed in  the  prefent  inftance,  ftiould  the  means  prove  fully  adequate  to  the  end,  it  will 
partly  confift,  as  will  be  feen  immediately,  in  my  having  given  an  entire  new  direftion  to 
another  ingenious  art  which  has  been  long,  cultivated,  and  by  none  with  fo  much  genius 
and  ability  as  by  the  jufliy  celebrated  Mr.    laffie  of  London. 

In  November  laft,  certain  circumftances  recalling  my  attention  to,  the  prefent  objed,  I 
was  led  to  explain,  by  letter  to  Mr.  Taffie.,  the  method  of  printing  at  the  rolling  prefs  with 
glafs-plates,  and  to  fpecify  to  him,  at  fome  length,  the .fteps  by  which  I  wiflied  him  im..» 

5  mediately 


62  Multiplicat'wn  tf  Glafs  Plates  for  Priiititig. 

medjatciy  to  proceed,  in  attempting  for  rac  the  execution  of  calls  or  copies  in  glafs  from 
eafUBkin  copper-plates  ■which  I  fent  him,  and  which  I  had  got  engraved  here  for  the  pur- 
pbfe<  4[t  afforded  me  much  fatisfailion  to  find  that  this  eminent  artifl  received  my  appli- 
cation with  great  candour,  and  that  lie  purfued  the  objeft  pointed  out  with  promptnefs, 
;tbout  which  I  had  applied  to  him  in  the  line  of  his  profeinon.  Though,  indeed,  at  the 
beginning  feme  difficulties  ftood  in  the  way,  yet  by  a  repeated  correfpondence,  and  tranf- 
jmiffion  of  different  effays  from  his  furnace,  anfwering  to  patterns  fent  up  at  different  times 
by  the  mail  coach,  Mr.  Taffie  foon  furniftied  me  with  feveral  calls  in  glafs  and  enamel, 
from  engraved  copper-plates,  which  appear  to  juftify  my  firft  conceptions,  and  to  go  fomc 
length,  even  thus  early,  to  enfure  the  fuccefs  of  the  plan  and  method,  which  I  had  brought 
forward. 

The  other  day  I  made  ready  for  printing,  three  of  thefe  plates ;  two  of  them  bearing 
infcriptions,  and  the  other  a  head  in  profile  from  Le  Brun.  I  might  have  mentioned  that 
the  plates,  when  fully  finilhed,  have  an  appearance  of  great  elegance;  thofe  efpecially 
which  are  made  of  white  glafs,  called  enamel ;  and  it  is  remarkable  how  eafily  they  are 
cleaned  from  the  ink,  in  the  courfe  of  the  workmen's  operations,  though  they  never  are 
heated  farther  than  by  handling  them.  From  the  three  plates  above  mentioned,  I  now  take 
the  liberty  of  fending  you  proofs  *,  or  impreffions,  inclofed.  So  far  as  I  know,  they  arc 
the  firft  of  the  kind  ever  produced.  As  the  very  firft  offerings,  therefore,  of  a  new  art, 
they  may  poffibly  appear  to  you  in  a  light  more  or  lefs  intercfting,  and  as  an  earneft  of 
fomething  confiderably  more  perfeft  foon  to  follow,  when  we  are  affifted  by  engravings  of 
fome  elegance,  and  executed  with  more  addrefs  in  feveral  refpe£ls,  with  a  view  to  a  de- 
(lination  fo  peculiar. 

It  will  notefcape  you,  that  by  means  of  a  feries  of  glafs  plates,  inconfulerable  in  point 
of  number,  deriving  the  engraving  from  the  fame  original  pattern,  to  fucceed  one  another 
at  the  prefs,  juft  before  figns  of  wearing  might  appear,  a  vaft  many  impreffions,  all  perfeSlly 
ftmilar,  might  be  obtained,  even  for  ages.  This  at  once  would  be  beftowing  a  new  cha- 
radler  upon  the  rolling  prefs,  which  hitherto  has  been  much  circumfcribed  in  this  refpe£l, 
by  the  perilhable  nature  of  engraved  copper-plates,  and  from  their  having  no  relation  to 
any  common  archetype.  Much  could  be  faid  of  the  advantages  of  thus  commanding  an 
«ver  enduring  identity  amongft  the  impreffions  afforded  by  engraved  plates,  even  of  a  fmall 
fize,  efpecially  in  the  inftance  of  circulating  Bank  Paper.  I  confefs,  indeed,  it  was  the 
frequent  alarming  forgeries  upon  fuch  currency,  efpecially  that  of  the  Bank  of  England, 
which  moved  me  in  November  laft  to  bring  to  experiment  the  prefent  fcheme,  which  has 
been  for  feveral  years  in  my  mind.  Should  the  glafs-plates  be  carried  to  a  fufficient  pitch 
of  delicacy,  1  perceive,  on  feveral  accounts,  that  they  would  afford  a  refuge  of  fingular 
importance  againft  all  attempts  of  forgery ;  provided  we  were  to  found  upon  archetypes  of 
iopper-plate  highly  elaborated,  and,  befides  the  mere  infcription,  exhibiting  by  collateral 
embellilhment  the  peculiar  manner  of  fome  eminent  mafter  in  the  art  of  engraving. 

•  It  would  have  been  evidently  ufelcfs  to  have  copied  theft  plates  by  way  of  exhibition  to  the  reader.  They 
are  not  diftinguidialile  from  copper-plate  prints ;  unlefs,  perhaps,  by  fome  minute  circumfianccs  arifing  from 
the  fubliqucnt  poli{hinj>  of  the  glafs.  But  this  lad  obfcivation  m«ft  be  uncertain,  unkfs  proofs  from  the  ori- 
jinal  topper  were  alfo  lud  for  cotnparifou. .  N, 

Before 


Impfcjtans  in  Glafs for  Pytnttn^,  6^ 

Before  concluding,  I  may  juft  mention,  that  fhould  the  methods  followed  by  Mr.  Taffie, 
of  moulding  with  plaifler  of  Paris  and  Tripoli,  not  afford  fufHcient  delicacy  to  the  plates, 
I  am  already  not  without  other  refources  likely  to  carry  us  farther  in  arrelling  an  art,  which 
feems  recommended  by  views  of  confiderablc  utility.  I  allude  here  partly  to  a  method 
•which  occurred  to  me  more  recently,  of  having  the  original  engraving  done  upon  a  flat 
and  poliflied  furface  of  fteel,  which,  by  the  fly  prefs,  may  be  communicated  to  a  flat  and 
polifhed  piece  of  pure  gold.  This  to  ferve  in  the  furnace  as  z.  permanent  mould  for  giving 
the  imprelTion  to  the  glafs.  From  fome  experiments  I  have  aftually  made  in  a  (mail  way, 
it  fliouldfeem  as  if  this  procefs  promifes  well ;  particularly,  by  giving  the  fire  furface  ftill 
more  delicacy,  and  which,  confequently,  would  require  ^  fmaller  degree  of  finifhing,  in 
the  procefs  for  bringing  it  ultimately  to  a  fufhcient  polifti ;  upon  which  circumftance  alone, 
now  depends  the  certainty  of  our  being  able  virtually  to  engrave  upon  glafs-plate,  with  a 
very  confiderablc  degree  of  perfection.  Should  it  be  neceflary  in  the  end  to  refort  to  the 
gold,  Mr.  Taffie's  confummate  flcill  and  addrefs  at  the  furnace,  in  the  application  of  the 
glafs,  would  doubtlefs  contribute  greatly  to  the  fuccefs. 

One  recommendation  amongft  others  of  this  method  would  be,  that,  from  the  in- 
deftru£lib!e  nature  of  pure  gold,  if  properly  managed  in  applying  the  heat,  all  the  plates 
would  aftually  be  derived  from  one  and  the  fame  mould ;  whereas,  by  the  other  method, 
the  moulds  themfelves,  which  are  neceflary  for  every  caft,  arc  derivative,  though  indeed 
from  the  fame  original  pattern. 

I  have  the  honour  to  be,  Sir, 

Your  moft  obedient  fervant, 

PAT.   WILSON. 

P.  S.  I  have  purpofely  referved,  to  follow  in  a  poflfeript,  a  very  ftiort  mention  of  another 
fubjc£l  bearing  a  clofe  analogy  to  the  foregoing. 

You  may  perhaps  know  that  of  late  years  the  art  of  cutting  defigns  upon  box-wood  has 
arrived  at  an  uncommon  degree  of  perfedion,  and  that  the  celebrated  Meffrs.  Bewicks, 
efpecially,  have  carried  their  execution  in  this  refpe£k  to  a  pitch  of  elegance  rivalling 
copper-plate,  and  which  was  believed  to  be  utterly  unattainable  before  their  time. 

Having  often  regretted  that  fuch  rare  fpecimens  of  art,  as  they  have  produced,  were 
fo  perifhable,  from  the  frailnefs  of  the  materials  upon  which  fo  much  genius  and  labour 
were  expended,  I  was  induced  alfo  to  fend  to  Mr.  Taflie,  amongft  other  models,  fome 
defigns  in  box-wood,  executed  by  Mr  Bewick,  with  direftions  to  mould  from  them, 
in  the  view  of  obtaining  calls  or  copies  in  glafs.  The  returns  which  I  received  to 
all  thofe  patterns  completely  anfwcred  my  expectations,  as  being  at  once  as  pcrfeCl  as  the 
originals. 

From  the  fuccefs  of  this  experiment,  which  alfo  I  have  had  long  in  contemplation,  and 
from  what  has  been  eftablilhed  in  the  way  of  making  glafs  fafely  refift  any  preffure,  it  will 
readily  occur  that  an  improvement  of  confiderable  magnitude  has  now  been  fhown  evi- 
dently to  depend  upon  a  proper  co-operation  of  the  two  arta  of  engraving  upon  box-wood, 
or  upon  brafs,  and  of  moulding,  with  a  view  of  obtaining  fuch  cuts  or  engravings  in  fo 

durable  a  fubdance  as  glafs. 

P.  W. 

III.     Injiru£iiens 


64  CemhuJJihility  o/Iron.-^Stet-/. 

III. 

InJIrunions  concerning  the  ManufaElure  of  Steel,  and  its  Ufes.     By  VaXDERMONDE,  MokgE, 
and  BerTHOLLET.     Pubiyijed  by  Order  of  the  Committee  of  Puhlic  Safety*. 


I 


Preliminary  Ohfervations. 


RON  is  a  combuflible  body.  It  lofes  its  metallic  properties  by  being  burned.  When 
iron  filings  are  expofed  to  flrong  heat  in  a  crucible,  and  frequently  ftirred  to  bring  the 
parts  fucceflively  in  contaft  with  the  air,  the  metallic  afpeiSt  difappears.  It  aflumes  a 
brick-duft  colour,  and  is  found  to  have  increafed  in  weight.  Part  of  the  air  of  the  atmo- 
fphere  has  combined  with  it,  and  produced  this  change.  This  portion  of  the  atmofphere 
is  called  oxygene. 

Iron  is  found  in  this  ftate  in  its  ores.  The  procefs  of  extracting  it  from  thefc  ores  prin- 
cipally confifls  in  depriving  it  of  oxygene. 

Charcoal  has  the  property  of  efFedling  this  change.  During  combuflion  it  abforbs  and 
unites  with  oxygene,  and  it  will  attradl  the  oxygene  from  iron  when  thefe  fubftances  are  in 
contadl  at  an  elevated  temperature.  Thefe  effefls  of  air  and  charcoal  are  very  perceptible 
when  tin  is  kept  in  fufion.  A  grey  pellicle  is  foon  formed  on  the  furface,  which  has  no 
metallic  fplendour.  If  this  pellicle  be  taken  off,  a  fecond  is  formed,  and  in  this  manner 
the  whole  of  the  tin  may  be  converted  into  a  fubftance  refembling  earth,  and  known  by  the 
name  of  drofs.  By  expofure  of  the  drofs  to  heat,  together  with  a  fmall  quantity  of  char- 
coal pow4er,  tallow,  or  refin,  the  oxygene  is  abforbcd  by  thefe  combuftible  fubftances,  and 
the  tin  becomes  reduced  to  the  metallic  flate. 

Charcoal  not  only  poflefTes  the  property  of  depriving  the  iron  of  the  air  which  was 
united  with  it,  but  it  is  alfo  capable  of  being  diffolved  in  the  iron  in  a  ftrong  heat,  and  by 
this  folution  it  communicates  new  properties  to  it.     It  changes  it  into  fteelf. 

Crude  or  call  iron  may  be  confidered  as  a  metal  not  completely  reduced,  which  confc- 
quently  retains  a  portion  of  the  bafis  of  air,  or  oxygene,  to  which  it  was  united  in  the  ore  ; 
and  as  this  reduftion  may  be  carried  farther  according  to  circumftances,  the  confequcnt 
variations  are  among  the  leading  caufes  of  the  different  properties  we  obferve  in  caft  iron. 
The  white  caft  iron  accordingly  holds  in  folution  much  oxygene  and  little  charcoal ;  the 
grey  caft  iron  on  the  contrary  contains  more  of  this  laft  fubftance,  but  is  much  more  pcr- 
feftly  deprived  of  oxygene.  A  greater  proportion  of  coal  muft  be  ufed  in  the  furnace  to 
obtain  this  laft.  The  properties  of  thefe  two  kinds  of  iron  depend  only  on  this  difference : 
the  former  is  more  brittle  and  fufible,  but  it  is  eafy  in  the  refining  furnace  to  deprive  it  of 
oxygene  by  the  aftion  of  ignited  charcoal,  which  combines  with  this  principle.  The  fe- 
cond has  retained  lefs  oxygene,  but  contains  much  more  charcoal.  It  is  fofter,  and  prefer- 
able for  fuch  ufes  as  require  this  foftnefs ;  but  it  is  more  difficult  to  convert  it  into 
malleable  iron,  becaufe  a  larger  portion  of  coal  is  required  to  be  deftroyed,  and  in  this 
ftate  it  confiderably  refifts  combuftion. 

•  I  have -omitted  a  few  political  reflections  of  a  temporary  nature  contained  in  this  memoir. 
+  Other  ingredients  enter  into  fteel,and  are  perhaps  effential  to  it,  particularly  phofphorus.     See  the  analyfis 
ofVauquefin.    Phiiof.  Journal,  I.  252. 

Forged 


Forged  Iron.    Steel.    Natural  Steel.  65 

: ,  Forged  iron  perfefHy  refined  would  confilt  of  the  metal  completely  reduced,  and  con- 
taining no  foreign  fubftance,  not  even  charcoal.  Such  iron  is  not  to  be  met  with  in  the 
market.  The  bed  Swedifli  iron  always  contains  a  portion  of  oxygene  which  has  efcaped 
the  operations  of  the  furnace  and  the  refinery,  and  it  is  always  contaminated  by  a  dofe  of 
charcoal,  very  fmall  indeed,  but  which  perhaps  it  is  impofllble  totally  to  eradicate. 

Other  circumftances  likewife  influence  the  qualities  of  iron,  particularly  with  refpefl  to 
the  fabrication  of  fteel.  This  metal,  according  to  the  nature  of  the  ores  which  afford  it, 
may  have  the  defefts  of  being  brittle  when  cold,  or  brittle  when  hot.  Thefe  are  refpec- 
tively  called  cold-fliort,  or  red-(hort  iron.  We  (hall  not  here  difcufs  the  caufes  which 
produce  thefe  bad  qualities*  •,  but  (hall  only  remark  that  fuch  iron,  or  its  ores,  affords  bad 
fteel,  and  muft  therefore  be  carefully  avoided. 

Steel  is  diltinguifhed  into  three  kinds :— natural  fleel ;  fteel  of  cementation  ;  and  cad 
fteel. 

*  Cetjcerning  Natural  Steel. 

THE  fteel  obtained  immediately  from  the  ore  by  fimple  fufion.  Is  called  natural  fteel. 
It  is  likewife  diftinguiftied  by  the  name  of  German  fteel,  becaufe  it  comes  principally 
from  Germany. 

Whether  the  crude  iron  (hall  afl"ume  the  nature  of  bar  iron,  or  of  fteel,  depends  on  cir- 
cumftances }  but  thefe  are  not  difficult  to  be  explained,  from  the  doftrine  already  laid 
down. 

Grey  crude  iron  is  alone  proper  to  afford  fteel ;  for  which  purpofe  it  is  requifite  that 
the  oxygene  it  contains  fhould  be  feparated,  and  the  coal  from  which .  its  grey  colour 
arifes  ftiould  be  intimately  combined  with  it.  The  converfion  of  the  crude  iron  into  fteel 
depends  on  thefe  procefTes  f . 

Hence  it  follows  as  a  leading  rule,  that  no  attempts  muft  be  made  to  convert  the  white 
crude  iron  into  fteel  in  this  way,  notwithftanding  it  may  be  capable  of  affording  excellent 
bar  iron.  The  firft  operation  muft  be  conduced  in  fuch  a  way  as  to  afford  grey  crude 
iron,  by  adding  a  greater  proportion  of  coal  in  the  charge  of  the  furnace. 

The  appearance  of  crude  iron  is  often  deceitful  with  refpeil  to  its  nature.  The  grey 
crude  iron  in  plates  or  fmall  portions,  fuddenly  cooled,  has  the  colour  of  the  white  crude 
iron.  But  the  nature  of  thefe  irons  may  be  afcertained  by  the  fimple  procefs  defcribed  at- 
the  end  of  this  memoir. 

When  a  proper  crude  iron  is  in  readinefs,  it  is  necelTary,  in  order  to  convert  it  into  bar 
iron,  that  it  fhould  be  much  more  expofed  to  the  aclion  of  the  air  by  frequent  ftirring,  and 
by  removing  the  fcorise  ;  but  when  fteel  is  defired,  it  is  lefs  expofed,  and  fuffered  to  remain 
covered  by  thofe  fcori*.  In  the  former  procefs  the  charcoal  is  burned  by  the  contadl  of 
the  air,  and  the  iron  is  left  confiderably  more  pure ;  but  in  the  fecond  the  charcoal  is  pre- 
ferved ;  part  of  which  combines  with  the  oxygene  which  ftill  remained  in  the  iron,  and 

•CoM-fliort  iron  is  aflforded  by  ores  whicli  contain  a  fmal!  portion  of  phofphoric  acid,  whicli  combines  with 
the  metal  in  the  ftate  of  phofphorus.  Red-ftiort  iron,  which  is  much  lefs  common  than  the  other,  contains 
arfenic;  but  it  is  probable  that  the  other  femi-metals  may  produce  the  fame  effeft.  AW  of  the  aulhors^ — Pro- 
tably  the  volatile  metals  may  moft  eminently  conduce  to  this  effeft.    N. 

\  See  Ehilof.  Journal,  I.  318. 

Vol.  II.— Mat  1798.  K  fcrves 


46  Prmffesfor  maktiig  Bat-  Iron  and  Natural  SUel. 

fcrves  to  feparate  it,  while  the  other  portion  combines  witk  the  iron  itfelf,  and  gives  it  tlic 
qualities  of  fteel. 

The  dlfpofition  of  the  hearth  or  fire-place,  and  the  pofition  of  the  tuyer  or  nozle  of  the 
bellows,  are  two  objeds  which  require  much  attention.  In  order  to  obtain  iron,  the  fire- 
place muft  be  larger  than  for  fteel,  and  the  tuyer  muft  be  inclined  fo  as  to  direft  the  blaft 
to  the  furfacc  of  the  iron.  The  hearth  is  to  be  filled  with  charcoal,  and  the  crude  iron 
placed  thereon  to  the  level  of  the  upper  part  of  the  tuyer.  The  heat  is  applied  mode- 
xatdy,  and  by  degrees,  in  order  that  the  iron  may  not  flow,  but  be  kept  in  the  ftate  of  a 
pafte.  It  is  to  be  ftirred  occafionally  with  the  rake,  frequently  brought  into  the  direftion 
of  the  blaft,  and  the  fcoriae  muft  from  time  to  time  be  taken  out. 

To  produce  fteel,  a  bed  of  fmall  or  powdered  charcoal  is  to  be  laid  round  the  fire-place, 
which  muft  be  moiftened  and  rammed  down.  Light  fufible  fcorise  are  added  ;  the  tuyer  is 
ufually  more  inclined,  and  the  fufion  more  haftily  urged,  in  order  that  the  metal  may  flow, 
and  immediately  fink  beneath  the  fcoriae,  which  are  not  removed  till  the  end  of  the  ope- 
ration. 

The  fame  procefles  are  not  every  where  followed  :  but  a  little  attention  ferves  to  (how 
that  they  are  all  founded  on  the  fame  principles ;  namely,  that  in  producing  fteel  the 
coaly  principle  of  the  iron  is  not  burned,  whereas  in  the  produ£lion  of  bar  iron  the  ope- 
ration is  fo  condu(Sted  as  to  burn  that  principle.  We  fliall  proceed  to  mention  fome  in- 
ftances. 

In  Styria,  where  good  fteel  is  made,  the  caft  iron  is  reduced  into  thin  plates,  which  are 
fufed  in  the  refinery.  The  ordinary  mafles  or  loupes,  which  have  been  fufi^ered  to  cool  in 
the  furnace,  inftead  of  having  been  drawn  ofl^,  are  alfo  fufed  for  fteel,  of  which  they  have 
begun  to  aflume  the  charafter  during  their  maceration  in  the  pot,  which,  with  this  inten- 
tion, was  lined  with  charcoal,  and  wherein  they  were  covered  with  the  fcoria:.  The  plates 
as  well  as  thefe  mafles,  which  are  prcvioufly  divided  into  fmaller  pieces,  are  refined  with 
the  precautions  neceflary  to  determine  the  formation  of  fteel. 

A  circumftance  which  contributes  much  to  the  goodnefs  of  the  fteel  is,  that  after  it  has 
been  drawn  out  by  the  hammer,  the  bars  are  thrown  red-hot  into  water,  and  afterwards 
broken  in  pieces  for  the  purpofe  of  feparating  the  perfe£l  fteel  from  that  which  is  of  the 
nature  of  iron.  The  hard  fteel  is  alfo  feparated  from  the  foft.  Packets  or  truffes  of  thefe 
are  made  up,  confifting  of  twelve  or  fifteen  pieces  each,  obferving  that  the  two  outer  pieces 
are  foft  fteel.  Thefe  truflcs  are  welded  together,  and  drawn  out  again  to  a  fmall  fize  ;  by 
which  means  the  quality  of  the  fteel  is  rendered  confiderably  more  uniform.  The  greatefl 
quantity  of  German  fteel,  as  well  as  that  which  is  moft  efteemed,  is  made  in  Carinthia^ 
Their  procefles  deferve  to  be  particularly  attended  to.  We  fhall  here  give  a  fliort  account 
of  the  particulars  from  Haflenfratz,  who  made  his  obfervations  on  the  fpot,  and  has  com- 
municated them  to  us. 

The  crude  iron  is  reduced  into  thin  plates,  or  leaves,  when  it  is  drawn  from  the  fmelt- 
ing  furnace.  For  this  purpofe  a  mould,  or  hemifpherical  cavity,  is  prepared  before  the 
furnace.  It  is  formed  of  the  fcoriae  reduced  into  very  fine  powder,  and  wetted  to  make 
them  adhere  together. 

The  work  is  then  opened  with  an  iron  bar,  in  order  that  the  fcorix  may  flow  into  the  mould, 
and  diflipate  its  moifture.  Thefe  are  in  the  next  place  taken  out,  and  the  metal  itfelf  is  fuffered 

to 


Prccepsfof  malihg  Sai-  Iron  and  Natural  Steel,  67 

to  flow  at  Erft  In  a  fmall  ftream,  and  afterwards  more  fpeedily.  The  aperture  is  enlarged 
in  proportion  as  it  flows  out,  and  at  laft  the  fcorise  fall  on  the  iron,  and  cover  it  in  the 
mould.  The  furnace  is  then  again  clofed,  and  the  blaft  renewed.  Water  being  thrown  on 
the  fcorise  which  occupy  the  upper  portion  of  the  mould,  they  become  fixed,  and  in  this 
ftate  are  removed,  A  fecond  portion  of  water  is  then  thrown  on  the  naked  furface  of  the 
metal,  which  congeals  to  a  fmall  depth.  The  thin  congealed  plate  is  taken  off,  and  a  fe- 
cond afperfion  of  water  is  made,  which  affords  a  third  plate.  In  this  manner  the  procefs  is 
continued,  until  as  much  of  the  metal  is  converted  into  plates  as  can  be  effedted  during 
the  fluidity  of  the  mafs. 

At  fome  works  the  iron  is  melted  in  a  particular  furnace  from  the  pig,  for  this  purpofc  ; 
but  this  fecond  operation  is  evidently  wafteful  both  of  time  and  fuel. 

The  plates  are  intended  to  be  made  into  either  iron  or  fteel. 

In  the  procefs  fot  making  bar  iron,  the  firft  operation  confifls  in  roafting  the  plates  on  a 
hearth,  upon  which  they  are  arranged  ;  a  palTage  being  formed  with  bricks,  in  order  that  the 
wind  of  the  bellows  may  be  diredled  from  one  extremity  to  the  other.  They  are  then  covered 
with  charcoal,  and  urged  ftrongly  with  the  bellows.  The  plates  by  this  roafting,  which 
dcftroys  the  charcoal  of  the  caft  iron,  begin  to  afTume  the  qualities  of  bar  iron,  after  which 
they  are  carried  to  the  finery  furnace.  The  body  of  this  furnace  is  more  capacious  than 
that  which  is  intended  for  fteel.  The  iron  is  covered  with  charcoal  and  fcorias,  and  the 
tuyer  is  inclined  fo  that  the  blafl.  ftrikes  on  the  plates  of  metal.  When  the  fufion  is  com- 
plete, the  fcorise  are  let  out,  the  mafs  is  frequently  turned  to  expofe  it  to  the  blaft,  and, 
laftly,  the  procefs  being  completed,  the  iron  is  conveyed  to  the  hammer. 

If  the  obje£l  be  to  form  fteel,  the  furnace  made  ufc  of  is  more  contradled  and 
deep.  It  is  lined  with  pulverized  charcoal,  moiftened  and  rendered  folid  by  beating. 
The  plates  are  difpofed  therein,  and  covered  with  fcoriae  and  charcoal.  The  pofition  of 
the  tuyer  is  nearly  horizontal,  in  order  that  the  ftream  of  air  may  ftrike  the  fuel,  and  not 
the  metal.  When  the  metal  begins  to  aflume  the  folid  ftate,  the  coal  is  taken  off,  the 
fcoriae  are  fufFered  to  flow  out,  and  fcales  and  fragments  of  fteel  are  driven  by  hammering 
into  the  foft  mafs. 

The  piece  is  afterwards  melted  a  fecond" time  with  the  fame  precautions  as  before  ;  and 
when  the  metal  is  thought  to  be  fufBciently  refined,  the  fcorias  are  drawn  off,  and  the 
mafs  is  conveyed  to  the  hammer  to  divide  it  into  feveral  pieces,  which  are  to  be  feparately 
forged  out. 

We  fee  that  all  thefe  operations  are  dire£led  to  the  means  of  deftroying  the  charcoal 
of  the  crude  iron,  when  bar  iron  is  wanted  ;  but  when  fteel  is  required  to  be  made,  the 
metal  is  not  only  preferved  from  the  contaft  of  the  air,  but  the  veffel  is  lined  with  char- 
coal, in  order  that,  by  its  contadt  with  the  fufed  matter,  it  may  fupply  any  portion  of  that 
principle  which  may  be  wanting. 

In  the  foregoing  procefs  there  are  two  fufions  of  the  metal.  In  the  latter  it  is  not  only 
completed  by  the  fecond  fufion,  but  it  is  rendered  more  homogeneous.  This  method  is  ex- 
cellent, and  is  perhaps  the  only  means  by  which  an  exceedingly  good  fteel  can  be  had. 

The  other  part  of  the  procefs  is  worthy  of  much  attention,  namely,  the  reduction  of  the 
crude  iron  into  plates.    When  bar  iron  is  wanted,  thefe  plates  roaft  with  more  facility 

K2  on 


68  Troeejfesfor  maiing  Steel. 

on  acpount  of  the  great  furface  they  prefent  to  the  air.  And  when  fteel  is  wanted,  they 
are  more  readily  fufed,  and  fink  beneath  the  fcorioe,  which  prevents  the  charcoal  of  the 
iron  from  being  confumed  by  the  adtion  of  the  air.  On  the  contrary,  they  abforb  what 
might  have  been  wanting  from  the  lining  of  the  veflel,  which  is  prepared  in  fuch  a  man- 
ner as  to  fupport  itfelf  without  being  confumed  through  the  whole  of  the  operation. 

When  the  fteel  has  congealed  in  the  furnace,  it  is  taken  out  and  divided  into  feveral  por- 
tions more  or  lefs  confiderable,  which  are  carried  to  the  hammer.  Here  a  feparation  is 
made  of  fuch  portions  as  are  not  reduced  into  fteel,  but  iron,  and  which  occupy  the  fur- 
face  of  the  pieces.  Each  piece  is  drawn  out  into  bars,  which  are  reduced  into  other 
fmaller  bars  of  different  dimenfions,  by  feparating  the  fofteft  parts  from  thofe  which  arc 
more  hard. 

For  fteel  of  a  fuperior  quality,  feveral  bars  of  the  foft  and  hard  kinds  are  united  by 
welding  and  forging.     The  hardeft  are  placed  in  the  middle. 

We  have  fliown  that,  in  order  to  obtain  fteel  from  crude  iron,  it  is  neceffary  to  have  an 
iron  abounding  with  coal ;  but  there  is  an  excefs  which  is  hurtful.  The  black  crude  iron, 
which  contains  too  much  coal,  affords  a  fteel  fo  brittle  as  to  be  of  no  ufe.  This  kind  of 
fl;eel  becomes  fixed  with  more  difficulty  than  good  fteel.  When  the  workman  perceives 
this  fymptom,  he  may  prevent  the  bad  effect  by  adding  a  certain  quantity  of  old  iron 
fragments,  which  deprives  the  too  fteely  metal  of  its  excefs  of  coal,  and,  by  incorporating 
with  it,  produces  an  uniform  mafs  of  good  fteel.  When  the  crude  iron  is  of  fuch  a  na- 
ture as  to  afford  brittle  fteel,  it  is  ufual  to  mix  in  the  refining  furnace  a  quantity  of  another 
kind  of  crude  iron,  which  may  modify  its  quality. 

Though  iron  and  fteel  are  diftinguifliable  by  very  ftrlking  qualities,  there  is,  neverthelefs, 
a  point  of  contact  at  which  they  are  confounded  :  the  fofteft  fteel  may  be  confidered  as  a 
very  hard  iron,  and,  in  faft,  the  feveral  kinds  of  iron  differ  in  hardnefs  by  the  fame  prin- 
ciple which  conftitutes  fteel.  They  all  retain  a  fmall  portion  of  charcoal,  which  efcapes 
the  operation  of  refining.  Thofe  which  contain  the  leaft  are  under  like  circumftances 
more  flexible,  foft,  duiftile,  and  fufceptible  of  acquiring  by  the  a£tion  of  the  hammer  that 
fibrous  form  which  conftitutes  what  is  called  the  grain  of  iron.  Hence  it  is  that  different 
kinds  of  bar  iron  are  fometimes  obtained  from  the  fame  crude  iron,  though  the  operation 
is  apparently  the  fame-  It  i^  fufficient  for  this  effe£t  that  the  inclination  of  the  tuyer  be 
changed. 

Concerning  Steel  obtained  by  Cementation. 

THE  fteel  of  cementation  is  formed  by  means  of  a  cement,  with  which  bars  of  forged 
iron  are  furrounded  in  a  cafe  difpofed  in  the  middle  of  a  furnace,  where  they  arc  fubjeded 
to  a  ftrong  heat. 

We  muft  repeat  that  the  good  quality  of  the  iron  is  a  condition  indifpenfable  for  obtain- 
ing good  fteel.  It  is  of  importance  to  choofe  the  heft  kind  ;  and  ^e  Englifh,  who  almoft 
cxclufively  prepare  the  fteel  of  cementation,  retain  for  that  objeft  all  the  iron  of  Roflagia, 
which  is  the  beft  iron  of  Sweden,  and  for  which  they  pay  a  high  price. 

It  is  not  enough  that  the  iron  (hould  contain  no  noxious  principle.  It  is  alfo  neceffary 
that  it  (hould  be  forged  with  care,  and  its  parts  well  united.    For  if  it  contain  flaws  or 

clefts 


Pnetjfesfor  tnailng  Sttel  by  Cemintation.  69 

clefts  within  the  bars,  they  become  much  more  perceptible  when  the  iron  has  acquired  the 
nature  of  fteel ;  and  it  would  not  be  praAicable  to  unite  them  perfc6lly,  becaufe  the  parts 
of  Iteel  arc  much  lefs  difpofed  to  weld  and  adhere  together  than  thofe  of  iron.  We  have 
had  convincing  proofs  in  our  own  experiments,  that  the  irons  of  France  of  good  quality, 
fuch  as  thofe  of  the  ci-devant  Berry,  afford  only  a  bad  fteel  when  cemented  in  the  ftate  they 
ufually  are  delivered  in  from  the  forge;  but  the  fame  iron,  after  having  been  carefully  forged 
and  hammered,  formed  fteel  equally  good  with  that  which  had  been  made  at  the  fame  time 
from  an  excellent  iron  of  Sweden.  In  another  experiment  the  fteel  prepared  with  iron  of 
the  ci-devant  comte  de  Foix,  which  had  been  well  forged,  produced  fteel  of  a  quality 
equal  to  that  which  had  been  obtained  in  the  fame  operation  with  Swedifli  iron. 

Hence  it  refults,  i.  That  the  beft  Swediftj  iron  owes  its  property  of  forming  good  fteel,  lefs 
to  any  particular  quality  of  the  ore  than  to  the  care  with  which  it  is  forged  and  fubmitted 
to  the  adtion  of  the  hammers:  2.  That  we  pofTefs  in  France  irons  capable  of  affording  good 
fteel,  provided  care  be  taken  that  they  be  well  forged ;  but  the  mere  negle£t  in  this  ope- 
ration may  prove  fatal  to  a  plan  in  other  refpefts  well  conduced. 

The  firft  attention  which  ought  therefore  to  be  paid  in  the  attempt  to  manufadture  fteel 
16  to  procure  good  iron,  to  examine  whether  it  be  well  forged  ;  and  in  cafe  this  operation 
has  not  been  fufficiently  attended  to,  it  muft  be  forged  and  made  found  before  it  is  fub- 
je£led  to  cementation. 

It  has  long  been  fuppofed  that  the  cement  proper  for  the  fteel-making  procefs  ought  to 
contain  faline,  inflammable,  fat  or  fulphureous  parts,  which  were  fuppofed  to  penetrate  the 
iron  and  change  it  into  fteel.  Hence  have  arifen  many  pretended  fecrets,  which  have  di. 
verted  the  attention  of  thofe  who  have  engaged  in  undertakings  of  this  kind  under  the 
guidance  of  ignorant  pretenders.  There  are  no  fecrets  in  the  compofition  of  the  cement. 
The  Englifti  ufe  no  material  but  the  charcoal  of  wood  reduced  to  powder  ;  and  in  fadl  the 
only  eflential  condition  is,  that  the  iron  fhould  become  impregnated  with  the  very  fubftance 
of  the  charcoal  uniformly  to  its  centre. 

When  the  bars  or  plates  of  iron  which  are  to  be  converted  Into  fteel  are  ready  for  the 
furnace,  they  are  cut  to  the  length  of  the  cafe  or  crucible  in  which  the  cementation  is  to  be 
made.  A  bed  of  charcoal  powder,  fifted  through  a  coarfe  Ceve,  and  flightly  wetted,  is  laid 
in  the  bottom  of  the  cafe.  Upon  this  is  placed  a  row  of  iron  bars  at  a  little  diftance  from 
each  other.  This  firft  layer  of  iron  is  then  covered  with  a  bed  of  charcoal  powder,  which 
fills  the  fpaces  within  the  bars,  and  rifes  to  the  height  of  half  an  inch  above  them.  A  new 
range  of  bars  is  then  laid  and  covered  with  charcoal  as  before,  and  in  this  fucceflive  way 
the  operator  proceeds  till  the  cafe  is  full.  The  laft  row  Is  covered  with  charcoal  pow^der, 
over  which  is  laid  a  bed  of  fand  to  cover  its  furface  entirely,  and  prevent  its  being  deftroyed 
by  combuftion.  The  fand  muft  be  moiftened  and  well  preffed  together  in  the  form  of  a 
roof.rifing  higher  than  the  fides  of  the  cafe,  fo  as  to  be  feveral  inches  thick  in  the  middle. 

When  the  preparation  or  charging  of  the  cafe  is  finiflied,  the  furnace  is  difpofed  for 
making  the  fire,  which  is  gradually  increafed,  and  muft  be  kept  up  for  a  longer  or  fhorter 
time  according  to  the  quantity  of  fteel,  and  confequently  according  to  the  fize  of  the  cafe.  • 
At  Newcaftle,  where  between  twenty-five  and  thirty  thoufand  weight  of  fteel  is  cemented 
in  two  cafes  contained  in  a  furnace,  the  operation  lafts  five  days  and  five  nights.     At. one 

of 


7»  Proctfsfar  maktng  Steel  iy  Cementation. 

of  the  extremities  of  the  furnace  as  well  as  of  the  cafe,  it  is  ufual  to  form  a  hole,  by  which 
a  bar  may  be  taken  out  when  it  is  fuppofed  that  the  cementation  may  be  fufficiently  ad- 
vanced. The  workman  judges  from  the  colour,  and  the  blifters  on  its  furface,  whether  the 
fteel  be  perfe£l.  If  he  cannot  depend  on  his  judgment  in  this  refpeft,  trial  is  made  of  this 
fteel  by  hardening  and  breaking  it.  If  the  cementation  have  not  penetrated  as  far  as  the 
centre,  it  is  eafy  to  diftinguifli,  by  the  fibrous  fraclure,  that  part  which  Hill  retains  the  nature 
of  iron. 

When  the  fteel  is  taken  out  of  the  cementing  furnace,  its  furface  is  covered  vt'ith  inequa- 
lities and  blifters,  whence  it  is  called  blifter  fteel.  In  this  ftate  its  frafture  prefents  very- 
large  facets,  and  refembles  brittle  iron  of  a  bad  quality.  Before  it  is  brought  to  market  it  is 
ufually  forged  into  flat  bars  feven  or  eight  lines  broad  ;  after  which  it  is  fiiffered  to  cool  in 
the  air  without  plunging  it  in  water.     By  this  treatment  its  grain  becomes  much  clofer. 

As  the  extremities  of  the  bars  thus  converted  into  fteel  are  ufually  flawed  and  lefs  per- 
feft,  they  are  cut  off  and  forged  together  in  faggots.  This  fteel  is  ufed  for  inftruments  of 
agriculture.  If  the  fire  have  not  been  fufficiently  a£live,  or  kept  up  for  the  proper  time, 
the  bars  are  not  cemented  to  the  centre ;  whence  they  become  of  unequal  hardnefs,  efpe- 
cially  if  they  be  not  very  carefully  forged.  When  the  fire  has  been  too  intenfc,  the  fteel  be- 
comes too  brittle,  and  difficult  to  be  managed  on  account  of  its  having  diflblved  too  large 
a  quantity  of  charcoal.  Yet  it  is  impoflible  to  eftablifli  any  rule  for  the  management  of 
the  firj:,  becaufe  it  muft  vary  according  to  the  form  and  fize  of  the  furnace,  the  number 
and  thicknefs  of  the  bars,  and  the  nature  of  the  fuel. 

The  form  and  magnitude  of  the  furnaces  vary  confiderably  in  the  different  works  where 
iron  is  cemented.  The  objefts  to  be  aimed  at  are,  to  give  the  furnace  a  degree  of  folidity 
which  ftiall  enable  it  to  refift  a  great  number  of  operations,  tocaufe  the  flame  and  heat  to 
circulate  equally  on  all  fides  of  the  cafe,  and  to  produce  the  greateft  quantity  of  heat  with 
the  fmalleft  expence  of  fuel. 

One  very  important  obfervation  refpe£llng  the  extent  of  dimenfions  which  may  be  given 
to  thefe  furnaces  is,  that  no  advantage,  or  at  leaft  very  little,  in  the  confumption  of  fuel  is 
obtained  by  enlarging  thefe  dimenfions,  becaufe  it  is  neceflary  that  the  whole  of  the  heat 
(hould  be  fuffered  to  diffipate  at  the  end  of  each  operation.  The  cafe  is  very  difl^erent  in 
other  manufadlories  where  the  accumulated  heat  may  ferve  for  fuccefllve  proceffes ;  for  the 
whole  of  fuch  fuel  as  is  employed  in  raiCng  the  temperature  to  the  neceflary  degree  in  cafes 
of  interruption  would  be  entirely  loft. 

Prudence  demands,  that  he  who  is  defirous  of  improving  or  extending  the  arts  fliould  not  • 
blindly  be  led  away  by  the  feduftion  of  projefts.     It  is  proper  to  begin  the  operations  on  a 
fmall  fcale,  in  order  to  render  the  pradice  familiar,  before  furnaces  of  a  certain  magnitude 
are  conftru£ted  *. 

(To  beconfludedy  with  Annotations,  in  our  next.  J 

*  Reference  is  here  made  in  the  original  to  drawings  of  furnaces  ;  one  contrived  by  Jars  for  cementing 
three  or  four  hundred  weight  of  fteel }  another  of  the  furnace  at  Newcaftle  ;  another  heated  by  wood,  toge- 
ther with  fome  defignt  relative  to  the  manipulations  at  Carinthia.  None  of  thefe,  however,  arc  annexed  » 
the  memeir.    K. 

6  IV.  Obfervations 


'.  Chemical  and  Economical  FaBs,  71 

IV. 

Ohfervat'tons  Chemical  and  Economical  on  various  SubjeEls  *. 

i.iVI.  TROMSDORFF,  Profeflbr  at  Erfart.has  obferved  that  fulphurated  hydrogenoUi 
gas  takes  fire  and  burns  with  a  ftrong  flame  by  means  of  the  nitrous  acid. 

2.  M.  Linck,  ProfefTor  at  Roftoc,  finds  that  three  parts  of  nitrous  gas,  and  two  of  hydl-b- 
genc  gas,  obtained  by  fulphuric  acid  and  iron,  are  fcarcely  or  not  at  all  diminifhed  when 
cxpofed  to  day-light  over  water.  Common  air  is  not  more  diminifhed  by  this  admixture 
kept  a  long  time  :  but  the  mixture  itfelf  of  thefe  two  gafes  is  diminifhed  by  the  addition 
of  new  portions  of  nitrous  gas.  M.  Linck  concludes  from  this  obfervation,  that  part  of 
the  oxygene  of  the  nitrous  gas  combined  with  the  hydrogenc  and  formed  water,  and  that 
the  remaining  oxygene  and  azote  formed  a  mixture  fimilar  to  the  air  of  the  atmofphere. 

Citizen  Vauouelin  made  a  (imilar  remark  ten  years  ago  on  nitrous  gas  placed  over  a  folii- 
tion  of  the  hydro-fulphuret  of  lime.     The  diminution  of  the  gas  was  confiderable. 

3.  The  urine  of  animals  which  feed  on  vegetables  does  not  contain  phofphoric  acid,  but 
an  acid  of  a  vegetable  nature.  On  this  paflage  C  Vauquelin  remarks,  that  Rouelle  an- 
nounced this  fa£t  twenty  years  ago,  and  that  C.  Foiircroy  and  himfelf  have  lately  proved  it 
by  a  great  number  of  experiments,  which  have  moreover  (hewn  that  the  acid  which  fup- 
plies  the  place  of  the  phofphoric  in  thefe  animals  is  the  benzoic. 

On  this  occafion  it  iriay  be  remarked,  that  the  vegetable  kingdom  afFords  phofphorus ; 
that  the  bones  which  are  produced  and  grow  in  animals  feeding  only  on  vegetable  food 
contain  this  fubftance  ;  whence  it  appears  probable  that  their  urine  is  not  at  all  times  di- 
vefted  of  phofphoric  acid.  M.  Giobert  in  his  memoir  on  phofphorus  ( Annales  de  Chimie, 
adi.  23.)  affirms  that  the  urifte  of  horfes  is  nearly  as  proper  for  his  procefs  as  that  of  men  ; 
that  is  to  fay,  that  it  affords  nearly  as  much  phofphorus.  But  he  does  not  pofitively  relate 
any  experiment  to  this  efFeft. 

4.  A  German  correfpondent  of  the  work  before  us  affirms,  that  the  blowing  machines  or 
bellows  for  the  iron  works  in  the  Hartz,  are  cubical  boxes  of  wood,  which  arc  more  eafily 
made  than  the  iron  cylinders  made  ufe  of  in  England,  and  that  they  are  very  advantageous 
in  the  ufe.  From  various  accounts  there  Is  reafon  to  think,  that  the  denfity  and  velocity 
of  the  flream  of  air  from  our  iron  cylinder  worked  by  a  fteam  engine  are  greater  than  has 
ever  been  afforded  by  the  wooden  bellows  or  other  blowing  engines  formerly  in  ufe.  The 
height  to  which  this  air  will  fupport  a  column  of  water  is  between  fix  and  feven  feet,  or  at 
a  medium  near  fix  inches  of  mercury. 

5.  Attempts  have  been  made  in  Saxony,  and  particularly  at  Fr^yberg,  to  increafe  the 
quantity  of  water  made  ufe  of  to  move  the  machines  in  that  country.  It  has  been  found 
convenient  to  eflablifh  pumps  worked  by  the  wind,  to  ralfe  a  portion  of  the  water  which 
palfes  through  the  galleries,  or  is  collefted  in  the  works.  It  is  not  intended  to  make  ufe  of 
this  inconftant  firfl  riiover  to  clear  the  mines  of  water,  but  fimply  to  fill  the  refervoirs 
which  work  the  hydraulic  machines,  at  the  fame  time  that  the  fecoiidary  advantage  of  affift- 
ing  to  keep  the  mines  clear  Is  obtained.  By  this  means  the  power  of  the  wind,  changeable 
ask  is,  may  be  rendered  fteadily  ufeful.    The  celebrated  Leibnitz  firft  thought  of  this  con- 

*  Journal  del  Mines,  No.  19. 

trivancc» 


ya  Salt-Werh  •without  Hfat.— 'Terra  AuJraUi,  "" 

trlvance,  and  endeavoured,  though  at  that  time  without  fuccefs,  to  carry  It  into  effeft.  I 
apprehend  that  his  refcrvoir  may  not  have  been  fufficiently  capacious.  Attempts  have 
been  made  in  England,  to  render  the  a£tion  of  fmall  ftreams  more  Ready  and  conflant  by 
the  intervention  of  a  refervoir,  which  fliould  retain  a  large  portion  of  the  water  when  wet 
weather  rendered  it  plentiful,  and  fupply  the  defeft  at  fuch  times  as  the  water  failed  for 
want  of  fuflicient  rain. 

6.  An  experiment  has  been  made  in  the  large  way  at  the  fall-work  of  Artern,  fituated  ia 
the  circle  of  Thuringia,  dependent  on  the  ele£lorate  of  Saxony,  on  the  poflibility  of  obtain- 
ing fea  fait  merely  by  the  heat  of  the  fun,  after  having  brought  the  fait  water  to  as  high  a 
degree  of  concentration  as  the  procefs  of  graduation  is  capable  of  affording.  This  fait  work 
was  the  firft  eftabliftiment  of  the  kind  in  Saxony,  by  Mr.  Borlach,  to  whom  the  undertakings 
of  this  nature  are  fo  much  indebted  ;  and  it  will  probably  have  the  honour  of  being  the  firft 
in  which  this  new  procefs  fhall  fucceed.  Experiments  on  a  fmaller  fcale  have  already  af- 
forded the  highefl  hopes  of  fuccefs.  Thofe  which  have  been  attempted  in  the  large  way, 
though  at  the  end  of  the  warm  weather,  have  afforded  encouraging  refults. 

For  this  purpofe  a  number  of  veflels  of  wood  have  been  placed  in  a  field  upon  polls,  at 
the  height  of  five  or  fix  feet  from  the  ground.  They  can  be  covered  or  uncovered  in  an 
inftant  by  a  moveable  roof  made  of  thin  boards,  accordingly  as  the  weather  is  clear  or 
rainy.  Though  the  fummcr  was  nearly  over  when  the  experiments  began,  fait  was  obtained 
in  this  manner  by  the  mere  heat  of  the  fun  ;  and  this  fait  was  much  purer,  and  of  a  more 
lively  and  agreeable  tafte,  than  that  which  is  obtained  by  evaporation  in  boilers.  There  is 
every  reafon  to  expeft  that  the  whole  of  the  fait  which  can  be  obtained  at  thefe  works,  will 
be  feparated  in  this  manner  without  the  ufe  of  any  combuftible.  A  great  number  of  thefe 
cafes  are  accordingly  prepared,  to  give  all  the  necefTary  adlivity  to  this  method  of  operating 
next  year. 

Citizen  Charles  Coquebert,  in  a  note  on  this  fubje<5t,  remarks  that  the  celebrated 
Haller  publifhed,  in  the  Memoirs  of  the  French  Academy  for  the  year  1764,  a  fet  of  expe- 
riments on  the  evaporation  of  falt-waters  made  at  the  works  in  the  canton  of  Berne,  of 
which  he  was  the  direflor;  and  adds,  that  the  experiments  are  interefting,  but  that  the  eco- 
nomical calculations  are  grounded  on  fuch  erroneous  foundations,  that  they  would  ferve  only 
to  miflead  thofe  who  from  the  reputation  of  the  author  might  ufe  his  calculations  relative 
to  any  undertaking  in  the  large  way. 


V. 

An  Attains  of  the  Earthy  Suhflance  from  New  South  Wales,  called  Sydneia^  tr  Terra  Atijl rails. 
By  Charles  Hatchett,  Efq.  F.R.S.* 


I 


N  I'pfij  tbc  Right  Hon.  Sir  Jofeph  Banks,  P.R.S.  favoured  me  with  a  fpecimen  of  the 
Sydneia,  which  had  been  lately  brought  to  England.  A  portion  of  this  I  foon  after  examin- 
ed, 

•  Fr«in  the  Philof.  Tranf.  179S.   The  introduftory  part  of  Mr.  Hatchett's  paper  concifely  ftates  the  refults 
»f  Wedgwood'i  paper  (from  which  an  eztraft  i«  copied  in  Philof. Journ.  1.405); — that  ProfeiTor  Blumenbach, 


ed,  In  a  curfory  manner,  by  muriatic  acid,  but  did  not  obtain  any  precipitate  when  water 
was  added  to  the  filtrated  folution. 

Upon  mentioning  this  circumilancc,  and  expreffing  a  defire  to  examine  this  fubftaBoe 
with  more  accuracy,  Sir  Jofeph  Banks,  with  his  ufual  readinefs  to  promote  every  fcientific 
enquiry,  not  only  permitted  me  to  take  fpecimens  from  different  parts  of  the  box  which 
contained  the  earth  already  mentioned,  but  (that  every  doubt  might  be  obviated)  gave  me 
about  300  grains  which  remained  of  the  identical  fubftance  examined  by  Mr.  Wedgwood. 

Upon  thefe  the  following  experiments  were  made  j  and,  to  diftinguifli  them,  I  (hali  call 
the  firft,  No.  I,and  that  examined  by  Mr.  Wedgwood,  No.  2. 

SECT.    11. 

^na/yjis  of  the  Sydnciz,  No.  i. 

THE  Sydneia,  No.  r,  is  in  mafles  and  lumps,  of  a  pale  greyifh  white,  intermixed  with  a 
few  particles  of  white  mica,  and  alfo  occafionally  with  fome  which  are  of  a  dark  grey,  re- 
fembling  graphite  or  plumbago. 

It  eafily  crumbles  between  the  fingers,  to  a  powder  nearly  impalpable,  which'has  rather 
an  un£tuous  feel. 

Small  fragments  of  vegetable  matter  are  alfo  commonly  found  intermixed  with  it ;  and 
the  general  afpe£t  is  that  of  an  earthy  fubftance  which  has  been  depofited  by  water. 

Experiment  i. — 400  grains  were  put  into  a  glafs  matrafs,  and  one  quart  of  diftilied  water 
being  added,  the  whole  was  boiled  to  one-fourth. 

The  liquor  was  then  filtrated,  and  a  portion  being  examined  by  the  re-agcnts  commonly 
ufed,  afforded  no  trace  of  matter  in  folution.  The  remainder  was  then  evaporated,  with- 
out leaving  any  rcfiduum. 

Experiment  2.  About  2co  grains  of  the  earth,  rubbed  to  a  fine  powder,  were  put  into  a 
glafs  retort,  into  which  I  poured  three  ounces  of  concentrated  pure  muriatic  acid.  The 
retort  was  placed  in  fand,  and  the  acid  was  diftilied,  till  the  matter  in  the  retort  remained 
dry.  Two  ounces  of  muriatic  acid  were  again  poured  on  it,  and  diftilied  as  before,  till 
only  one  fourth  remained.  The  whole  was  then  put  into  a  matrafs,  which  was  placed  in 
an  inclined  pofition,  fo  that,  when  the  earth  had  fubfided,  the  liquor  might  be  decanted 
without  difturbing  the  fediment. 

"When  it  had  remained  thus  for  12  hours,  the  acid  was  carefully  poured  into  a  glafs 
veffel :  but,  as  I  obferved  that  it  was  not  fo  perfedlly  tranfparcnt  as  before  it  had  been  thus 
employed,  I  fuffered  it  to  remain  24  hours,  but  did  not  perceive  any  fediment.  Half  of 
this  liquor  was  diluted  with  about  twelve  parts  of  diftilied  water,  and,  after  a  few  hour^a, 
a  very  fmall  quantity  of  a  white  earth  fubfided. 

in  his  Handbuch  itt  Naturgefchichte,  p.  567,  568.  mentions  that  he  had  examined  a  portion  of  this  earthy 
fubftance,  by  means  of  muriatic  acid  after  the  manner  of  Wedgwood,  and  obtained  a  flight  precipitate ;— that 
M- Klaproth  had  alfo  examined  it,  whofe  refults  he  likewife  gives  (for  which  fee  the  page  of  our  Journal  laft 
mentioned) ; — and  that  the  identity  of  the  fubjefts  examined  by  Wedgwood  and  Klaproth  had  been  muqh 
ijueftioned  by  ipe.  The  author  tlien  proceeds  to  relate  the  hillory  ^nd  particulars  of  his  own  analyfis,  of 
which  the  wordt  of  the  text  are  ao.exaft  copy.     N. 

Vol.  II.— May  1798.  L  ThJ» 


^4  Attaints  of  the  Sydney  Earth. 

This  however  did  not  appear  to  me  to  be  a  precipitate  caufed  by  a  change  in  the  cKennical 
affinities,  but  rather  an  earthy  matter  which  had  been  fufpended  in  the  concentrated  acid, 
"and  afterwards  depofited,  when  the  Hquor  was  rendered  lefs  denfe  by  the  addition  of  wa- 
ter. To  afcertain  this,  I  poured  the  remaining  portion  of  the  concentrated  liquor  on  a 
•filter  of  four  folds  :  it  paffed  perfedlly  tranfparent,  and,  although  diluted  with  twenty-four 
parts  of  water,  it  remained  unchanged,  and  as  pellucid  as  before.  1  now  filtrated  the  for- 
mer portion,  and  added  it  to  that  already  mentioned. 

It  was  then  evaporated  to  drynefs,  and  left  a  pale  brownifh  mafs,  which  was  diflblved 
again,  by  digeftion,  in  the  fmallefl  polTible  quantity  of  muriatic  acid. 

Water  was  added,  in  a  very  large  proportion,  to  this  folution,  without  producing  any 
effe<ft ;  I  then,  by  pruffiate  of  potafli,  precipitated  a  quantity  of  iron,  which  was  feparated 
by  a  filter. 

The  clear  folution  was  then  faturated  with  lixivium  of  carbonate  of  potafli,  and  a  white 
precipitate  was  produced,  which  was  colleded  and  edulcorated.  This,  when  digefted 
with  diluted  fulphuric  acid,  was  diflblved  ;  and  the  fuperfluous  acid  being  driven  off"  by 
heat,  boiling  water  was  poured  on  the  refiduum,  and  completely  diflblved  it. 

To  this  folution  fome  drops  of  lixivium  of  potafli  were  added,  and,  by  repeated  evapora- 
tions, the  whole  formed  cryftals  of  alum. 

From  the  above  experiment  it  appeared,  that  the  muriatic  acid  had  only  diflblved  fome 
alumine  and  iron  ;  but,  in  order  to  fatisfy  myfelf  more  completely  in  refpeft  to  the  com- 
ponent parts  of  this  fubfl;ance,  I  made  the  following  analyfis. 

Jnalyfts.  A.  400  grains  were  put  into  a  glafs  retort,  which  was  then  made  red-hot 
during  half  an  hour.  Some  water  came  over,  and  the  earth  afterwards  weighed  380.80 
grains,  fo  that  the  lofs  amounted  to  19.20  grains.  The  greater  part  of  this  lofs  was  occa.- 
fioncd  by  the  diflipation  of  the  water  imbibed  by  the  earth  ;  to  which  muft  be  added,  the 
lofs  of  weight  caufed  by  the  conibufl;ion  of  a  fmall  portion  of  vegetable  matter. 

B.  The  380.80  grains  were  rubbed  to  a  fine  powder,  and  being  put  into  a  glafs  retort, 
1470  grains  of  pure  concentrated  fulphuric  acid  were  added.  The  retort  was  then  placed 
in  a  fmall  reverberatory,  and  the  fire  was  gradually  increafed,  till  the  acid  was  difl.il!ed 
over :  it  was  then  poured  back  on  the  matter  in  the  retort,  and  diftilled  as  before,  till  a 
mafs  nearly  dry  remained. 

On  thisjboiling  diftilled  water  was  repeatedly  poured,  until  it  no  longer  changed  the  colour 
of  litmus  paper,  and  was  devoid  of  tafte.  The  undiflblved  portion  was  then  dried,  and  made 
red-hot;  after  which  it  weighed  281  grains. 

C.  I  now  mixed  the  281  grains  with  300  grains  of  dry  carbonate  of  potafli,  and  expofed 
the  mixture  ^o  a  ftrong  red  heat,  in  a  filver  crucible,  during  four  hours.  The  mafs  was 
loofe,  and  of  a  greyifli  white :  it  was  foftened  with  water,  and,  being  put  into  a  re- 
tort, fulphuric  acid  was  added  to  a  eonfiderable  excefs.  The  whole  was  then  diflilled 
to  drynefs;  and  when  a  fuflicient  quantity  of  boiling  water  had  been  added,  it  was 
poured  on  a  filter,  and  the  refiduum  was  well  waflied :  it  was  then  made  red-hot,  and 
aften\'ards  weighed  274.75  grains. 

D.  The  folutions  of  B  and  C  were  added  together,  and  were  much  reduced  byevapora- 
tion.    Pure  ammoniac  was  then  employed  tg  faturatc  the  acid,  and  a  copious  loofe  preci- 

"     '  pitate 


Anal^isofthe  Sydney  Earth.  figi 

pltate  of  a  pale  yellowlfli  colour  was  produced ;  which,  colle£led,  edulcorated,  and  made 
red-hot,  weighed  103.70  grains.  '  '/■'  .■<.r.>1 

E.  The  filtrated  liquor  of  D  was  again  evaporated  ;  and  carbonate  of  potafli  -being' 
added,  a  flight  precipitation  of  earthy  matter  took  place ;  which,  by  the  teft  of  fulphuric 
acid,  proved  to  be  fome  alumine  which  had  not  been  precipitated  in  the  former  experi- 
ment:  this  weighed  1.20  grain. 

F.  The  103.70  grains  of  D  were  completely  diflblved  when  digefted  with  nitric  acid, 
excepting  a  fmall  refiduum  of  filiceous  earth,  which  weighed  0.90  grain. 

G.  The  nitric  folution  was  evaporated  to  drynefs,  and  a  fecond  portion  of  the  fame  acid 
was  added,  and. in  like  manner  evaporated.  The  refiduum  was  then  made  red-hot,  and 
digefted  with  diluted  nitric  acid,  which  left  a  confiderable  portion  of  red  oxyde  of  iron. 
The  folution  was  again  evaporated,  and  the  refiduum,  being  treated  as  before,  again  de- 
pofited  fome  oxyde  of  iron,  much  lefs  in  quantity  than  the  former. 

The  whole  of  the  oxyde  was  then  heated  with  wax  in  a  porcelain  crucible,  was  taken  up 
by  a  magnet,  and  weighed  26.50  grains. 

H.  The  nitric  folution  of  G  was  faturated  with  ammoniac,  and  a  loofe  white  preci- 
pitate was  formed ;   which,  edulcorated  and  made  red-hot,  weighed  76  grains. 

I.  Thefe  76  grains  were  diflblved  when  digefted  with  diluted  fulphuric  aid;  and,  when 
the  excefs  of  acid  had  been  expelled  by  heat,  the  faline  mafs  was  diflblved  in  boiling  water. 
To  this  folution  I  added  fome  lixivium  of  potafh,  and,  by  gradual  and  repeated  evapora-. 
tions,  obtained  the  whole  in  regular  odtoedral  cryftals  of  alum. 

K.  The  274.75  grains  of  C  now  alone  remained  to  be  examined.  They  appeared  to 
confift  of  filiceous  earth,  mixed  with  the  dark  grey  (hining  particles  already  mentioned ; 
but,  as  I  Ihall  defcribe,  in  the  following  experiments,  the  procefs  by  which  thefe  were  fe- 
narated,  I  fliall  now  only  fay  that  they  amounted  to  7.50  grains. 

L.  The  earth  with  which  the  abovementioned  particles  were  mixed  weighed  267.25 
grains.  This  earth  was  white,  and  arid  to  the  touch  :  when  melted  with  two  parts  of  foda. 
It  formed  a  colourlefs  glafs  ;  and  with  four  parts  of  the  fame  it  diflblved  in  water,  and 
formed  a  liquor filicum  :  it  was  therefore  pure  filiceous  earth  or  filica. 

The  fubftance  here  examined  was  compofed  therefore  of  the  following  ingredients : 

Grains. 


Pure  filiceous  earth  or  filica 
Alumine         -         _  , 


0.90 
267.25 
1.20 
76 

Oxide  of  iron         -  .         .         .         G.      26.50 

Dark  grey  particles  -  -  K.       7.50 

Water  and  vegetable  matter  -  A.     19.20 


{h: 


398-55 

.  The  foregoing  analyfis  was  repeated  feveral  times,  and  always  with  fimilar  refults  ;  ex- 
cepting that,  as  I  had  taken  the  fpecimenr  from  different  parts  of  a  large  quantity,  I  found 
that  the  proportioKS  of  the  ingredients  were  not  conftanUy  the  fame ;_  that  of  the  filiceous 

L  2  earth. 


^  Anal<jfts  efthe  Sydiuy  Marth, 

tvtxh,  for  examplct  was  fometimes  greater,  and  the  alumine  and  iron  proportlonably  left. 
Some  fpeciniens  were  alfo  nearly  or  totally  deftitute  of  the  dark  grey  fliining  particles  :  in 
fliort,  <:yery  circumftance  wa»  fuch  as  might  be  expected  from  a  mixed  fubftance,  which, 
from  the  nature  of  its  formation,  cannot  have  the  ingredients  in  any  fixed  proportion  *. 

As  this  fubftance  agreed  in  its  general  chara£lers,  for  the  greater  part,  with  tlwt  <k- 
fcribed  by  Mr.  Wedgwood,  and  as  it  was  indifputably  brought  from  the  fame  place,  there 
appeared  every  reafon  to  believe  that  the  nature  of  both  was  the  fame  ;  but,  to  obviate  as 
much  as  poffible  any  doubt  or  objection,  I  determined  to  repeat  the  experiments,  and  the 
analyfis,  on  that  portion  which  remained  of  the  identical  fubftance  examined  by  Mr. 
Wedgwood,  and  which  from  that  period  had  been  referved  by  Sir  Jofeph  Banks,  who 
kindly  favoured  me  with  it  for  this  purpofe. 

SECT.    III. 

Jnalyfis  of  the  Sydiieia,   No.  2. 

TPIIS  fubftance,  as  has  already  been  mentioned,  confifts  of  a  white  tranfparent  quartzofe 
fand,  a  foft  opaque  white  earth,  fome  particles  of  white  mica,  and  a  quantity  of  dark  lead- 
grey  particles,  which  have  a  metallic  luftrc. 

The  Sydneia,  No.  2,  appears  chiefly  to  differ  from  No.  i,  by  being  more  arenaceous, 
and  by  a  larger  proportion  of  the  dark  grey  particles.  Many  experiments,  fimilar  to  thofe 
made  on  No.  I,  already  defcribcd,  were  made  on  this  fubftance,  with  pure  concentrated 
muriatic  acid ;  but,  as  none  of  thefe  afforded  any  appearance  of  a  precipitate  by  the  means 
of  water,  I  do  not  think  it  neceffary  to  enter  into  a  circumftantial  account  of  them,  and 
ihall  proceed  therefore  to  the  analyfis. 

A.  100  grains  were  expofed  to  a  red  heat,  in  a  glafs  retort,  and,  after  half  an  hour,  were 
found  to  have  loft  in  weight  2.20  grains. 

B.  The  97.80  grains  which  remained  were  mixed  with  300  grains  of  dry  carbonate  of 
potafh,  and  the  mixture  was  expofed  to  a  ftrong  red  heat,  in  a  crucible  of  filver,  during 
three  hours. 

When  cold,  the  mafs  was  foftened  with  water,  and  was  put  into  a  glafs  matrafs.  I 
then  added  three  ounces  of  pure  concentrated  muriatic  acid,  and  digefted  it  for  two 
hours  in  a  ftrong  fand  heat.  BoiHng  water  was  then  added  ;  and  the  whole  being  poured 
on  a  filter,  the  refiduum  was  edulcorated,  dried,  and  made  red-hot :  it  then  weighed  85.50 
grains. 

C.  The  filtrated  folution  was  evaporated  to  one  fourth ;  and  pure  ammoniac  being  added, 
a  precipitate  was  formed,  which,  after  a  red  heat,  weighed  10.70  grains. 

D.  One  ounce  of  muriatic  acid  was  poured  on  the  to. 70  grains,  in  a  matrafs,  which  was 
then  heated.  The  whole  erf' the  10.70  grains  was  diflblved,  excepting  a  fmall  portion  of 
Cliceous  earth,  which  weighed  0.30  grain. 

•  The  defcription  given  by  Mr.KIapreth  convinces  me  that  his  experiments  were  made  on  a  portion  of  this 
fubftance.  •  Moreover,  wlien  my  late  friend  Mr.  Haidingcr  was  in  London,  I  gave  him  fome  of  this  earth  fop 
bis  colle£lion ;  fo  that,  whether  Mr.  Kl'aproth  made  his  experiments  on  that  which  had  be«n  received  by 
Mr.  Haidinger  from  Sir  Jofeph  Siknks,  or  from  mjfcff,  it  i*  not  lesfb  certain  that  he  operattd  en  tkat  which 
Mig^  be  regarded  a«  (Iw  geiMune  $<«)iW«. 

E,  The 


Analyfts  of  the  Sydney  Earth'  fi 

E.  The  muriatic  folution  was  then  reduced,  by  evaporation,  to  aSout  one  fourth ;  to 
which  I  added  a  large  quantity  of  diflilled  water,  which  did  not  however  produce  any 
change.  1  then  gradually  added  a  folution  of  pure  cryftillized  prufliate  of  potafli,  and 
heated  the  liquor  till  the  whole  of  the  iron  was  precipitated ;  after  which,  ammoniac  pre- 
cipitated a  loofe  white  earth,  which,  edulcorated  and  made  red-hot,  weighed  7.20  grains. 
The  iron  precipitated  by  the  prufliate  may  therefore  be  eftimated  at  3.20  grains. 

F.  The  7.20  grains  of  the  white  earth  were  digefted  with  fulphuric  acid,  and,  after 
the  cxcefs  of  acid  had  been  expelled  by  heat,  boiling  water  was  poured  on  the  faline 
refiduum.  The  folution  was  then  gradually  evaporated,  with  the  addition  of  a  fmall 
portion  of  lixivium  of  potafh,  and  aftbtded  cryftals  of  alum,  without  a  trace  of  any  other 
fubftance. 

G.  I  now  proceeded  to  examine  the  85.50  grains  of  B.  Thefe  appeared  to  confift  of 
filiceous  earth,  or  fine  particles  of  quartz,  mingled  with  a  confiderable  quantity  of  the  dark 
grey  flilning  particles. 

Mr.  Wedgwood  was  of  opinion  that  thefe  were  a  peculiar  fpecies  of  plumbago  ot 
graphite.  Profeflbr  Blumenbach,  on  the  contrary,  regards  them  as  molybdana  :  and  Mr. 
Klaproth  believes  them  to  be  eifeitglimmer  or  micaceous  iron  ore. 

When  rubbed  between  the  fingers,  they  leave  a  dark  grey  ftain,  and  the  feel  is  utiftuous, 
like  that  of  plumbago,  or  molybdjena  :  the  traces  which  they  make  on  paper  alfo  refemble 
thofe  of  the  abovementioned  fubftances,  but  the  luftre  of  the  particles  approaches  nearer  to 
that  of  molybdsena. 

In  order  therefore  to  determine  whether  or  not  they  confifted  totally  or  partially  of  mo- 
lybdxna,  I  put  the  85.50  grains  into  a  fmall  glafs  retort,  and  added  two  ounces  of  con- 
centrated nitric  acid.  The  retort  was  then  placed  in  a  fand  heat,  and  the  diftillation  was 
continued  till  the  matter  remained  dry.  The  acid  was  then  poured  back  into  the  retort, 
and  diftilled  as  before ;  but  I  did  not  obferve  that  the  grey  particles  had  fufFered  any  change, 
nor  were  nitrous  fumes  produced,  as  when  molybdxna  is  thus  treated. 

To  be  more  certain,  however,  I  digefted  pure  ammoniac  on  the  refiduum  ;  and,  having 
decanted  it  into  a  matrafs,  I  evaporated  it  to  drynefs,  without  perceiving  any  veftige  of 
oxyde  of  molybdsna,  or  indeed  of  any  other  fubftance. 

It  was  evident,  therefore,  that  molybdaena  was  not  prefent ;  and,  as  the  general  external 
charafters  and  properties  correfponded  with  thofe  of  plumbago,  I  was  inclined  to  believe 
that  thefe  were  particles  of  that  fubilance,  and  not  micaceous  iron,  as  Mr.  Klaproth  ima- 
gined.   To  determine  this,  the  following  experiment  was  made  : 

H.  200  grains  of  pure  nitre  in  powder  were  mixed  with  the  85.50  grains,  and  the  mix- 
ture was  gradually  projefted  into  a  crucible,  made  ftrongly  red-hot.  A  feeble  detonation 
took  place  at  each  pro]e£l:i©n  j  and,  after  a  quarter  of  an  hour  bad  dapfed,  rhe  crucible 
was  removed. 

When  cold,  the  mafs  was  porous  and  white,  without  any  appearance  of  the  i»rk  grey 
particles.  Boiling  water  was  poured  on  it ;  and  the  whole  being  put  into  a  matrafs,  one 
ounce  of  muriatic  acid  was  added,  and  digefted  with  it  in  a  fand  heat.  By  evaporation  it 
became  gelatinous :  it  was  then  emptied  en  a  filter,  and,  being  well  walhed,  dried,  and  made 
jedrhot,  weighed  75.25  grains. 

Ibe  appearance  of  this  was  that  of  a  wbke  earth,  uiA  I9  Ih*  toueh.    Whpn  melted 

6  with 


^S  Anal'^is  of  the  SyJtxy  Earth. 

with  two  parts  of  foda,  a  colourlefs  glafs  was  formed  ;  and,  with  four  parts  of  the  fame,  It 
was  foluble  in  water,  and  produced  liquor  ftlicum  :  it  was  therefore  pure  filiceous  earth. 

I.  The  filtrated  liquor  was  faturated  with  ammoniac ;  and,  upon  being  heated,  a  few 
brownifli  flocculi  were  precipitated,  which,  when  colle£led  and  dried,  weighed  0.40  grain. 
This  precipitate  was  diflblved  in  muriatic  acid,  and  was  again  precipitated  by  pruffiate  of 
potafli,  in  the  ftate  of  Pruffian  blue. 

The  liquor  from  which  the  flocculi  of  iron  had  been  feparated  was  then  examined,  by 
adding  carbonate  of  potalh,  and,  laftly,  by  being  evaporated  to  drynefs ;  but  it  no  longer 
afforded  any  earthy  or  metallic  fubftance  :  fo  that,  by  the  procefs  of  detonation  with  nitre, 
the  85.50  grains  afforded  75.25  grains  of  pure  filiceous  earth,  with  0.40  grain  of  iron  ;  and, 
as  the  dark  grey  fubftance  was  deftroyed,  excepting  the  0.40  grain  of  iron  above  mentioned, 
and  as  9.85  grains  of  the  original  weight  of  ^5.50  grains  were  diffipated,  there  can  be  no 
doubt  but  that  this  fubftance,  amounting  to  1O.25  grains,  was  carburet  of  iron  or  plumbago  ; 
efpecially  as  fome  experiments  which  I  purpofely  made,  on  that  from  Kcfwick  in  Cum- 
berland, were  attended  with  fimilar  refults. 

It  is  alfo  evident,  that  thefe  particles  could  not  be  eife/iglimmer,  or  micaceous  iron,  as 
nitre  has  little  or  no  efFeft  on  that  fubftance,  when  projedted  into  a  heated  crucible. 

In  a  fubfequent  experiment  on  the  fame,  the  crucible  was  removed  immediately  after  the 
Jaft  projection;  and  1  then  obferved  that  an  efFervefcence,  with  a  difengagement  of  carbonic 
acid,  took  place,  upon  the  addition  of  the  muriatic  acid,  as  is  ufual  when  pure  plumbago  is 
decompofed  by  nitre,  and  that  lefs  of  the  gelatinous  matter  was  formed  by  evaporation. 

The  caufe  of  this  difference  was  evidently  the  duration  of  the  red  heat ;  for,  in  the  firft 
inftance,  the  alkali  developed  by  the  decompofition  of  the  nitre  had  time  to  unite  with  the 
filiceous  earth,  fo  as,  when  dilTolved,  to  form  liquor  ftlicum  ;  but,  in  the  fecond  experiment, 
a  portion  of  alkali  remained  combined  with  the  carbonic  acid,  produced  by  the  carbon  of 
the  decompofed  plumbago. 

The  produce  of  100  grains  by  this  anaiyfis  was, 


Silica 


{. 


D.    0.30 
.H.  75.25 

Alumlne  -  -  -        F.     7.20 

Oxide  of  Iron  -  -  E.    3.20 

Graphite  or  plumbago  -  I.   10.25 

Water  -  -  A.    2.20 

98.40 

Mr,  Wedgwood  fays,  that  fulphuric  acid  cannot  dilTolve  the  precipitated  earth,  and  has 
but  Httlc  eflFeft  on  the  mixed  fubftance,  even  when  diftilled  to  drynefs  ;  but,  from  the  pre- 
ceding experiments,  I  had  reafon  to  believe  that  the  aluminous  earth  and  Iron  would  be 
feparated  by  reiterated  diftUlatlon ;  I  therefore  repeated  the  anaiyfis  in  the  following  man- 
ner. ' 

Second  Anaiyfis  of  the  Sydneia,  No,  2. 
A.    100  grains  of  the  earth  were  put  into  a  glafs  retort,  upon  which  400  grains  of  pure 
concentrated  fulphuric  acid  were  poured.    The  retort  was  placed  in  a  fmall  reverberatory, 

and 


^nalyfis  of  the  Sydney  Earth,  yg  \ 

and  tht  fire  was  continued  till  a  dry  mafs  remained.  400  grains  of  the  acid  were  again 
poured  in,  and  diftiljedas  before.  Upon  the  dry  mafs  boiling  water  was  poured,  and  the 
whole  was  then  emptied  on  a  filter,  and  edulcorated.  The  refiduum,  after  a  red  heat, 
weighed  87.75  grains,  and  confided  of  filiceous  earth,  mixed  with  fome  mica,  and  with 
particles  of  plumbago. 

B.  The  filtrated  folution,  by  ammoniac,  afforded  a  precipitate,  which  weighed  g.50 
grains  ;  and,  being  examined,  as  in  the  former  experiment,  yielded  6.50  grains  of  alumine, 
and  3  grains  of  oxide  of  iron. 

The  plumbago  was  feparated  from  the  filiceous  matter,  in  the  manner  already  defcribed, 
and  amounted  to  about  10  grains. 
]3y  this  analyfis  I  obtained. 

Grains. 
Silica  and  mica  -  -  77-75 

Alumine  -  -  -  6.50 

Oxide  of  iron  -  -  ■  3 

Plumbago  -  -  -  10 


97.25 

It  appears  therefore  that  the  Sydneian  earth,  when  treated  with  fulpliuric  acid,  is  capa- 
ble of  being  for  the  greater  part  decompofed  ;  and  Mr.  Wedgwood  probably  did  not  fuc- 
ceed,  becaufe  his  procefs  was  in  fome  refpe£t  different,  or  that  the  diflillation  was  not 
fufhciently  repeated. 

1  have  not  thought  it  necefTary  to  be  more  circumftantial  in  the  account  of  this  fecond 
analyfis,  as  the  operations  were  fimilar  to  thofe  of  the  former. 

SECT.    IV. 

THESE  experiments  prove,  that  the  earthy  fubftance  called  Sydnela,  or  terra  au/Jralisy 
confifts  of  filiceous  earth,  alumine,  oxide  of  iron,  and  black  lead  or  graphite. 

The  prefence  of  the  latter  appears  to  be  accidental,  and  it  probably  was  mixed  with  the 
other  fubflances  at  the  time  when  they  were  tranfported,  and  depofited,  by  means  of  wa- 
ter ;  for  this  appears  evidently  to  have  been  the  cafe,  from  the  general  characters  of  this 
mixed  earthy  fubftance. 

The  quartz  and  mica,  which  are  fo  vifible,  indicate  a  granitic  origin  ;  and  the  foft  white 
earth  has  probably  been  formed  by  a  decompofition  of  feldt  fpar,  fuch  as  is  to  be  fecn  in 
many  places,  and  particularly  at  St.  Stephen's  in  Cornwall.  The  granitic  fand  which  co- 
vers the  borders  of  the  Mer  de  Glace-,  at  Chamouni,  in  Savoy,  alfo  much  refembles  the 
ttrra  aiifiralis,  excepting  that  the  feldt  fpar  is  not  in  a  ftate  of  decompofition  ;  in  fhort, 
the  general  afpeft,  and  the  analyfis,  concur  to  prove,  that  the  Sydneia  has  been  formed  by 
the  difintegration  and  decompofition  of  granite,  or  gneifs. 

Mr.  Wedgwood's  experiments  are  fo  circumftantial,  that  had  I  only  examined  the  earth ' 
laft brought  to  England,  I  (hould  have  fuppofed,  with  Mr.  Nicholfon,  that  I  had  operated 
on  a  different  fubftance  ;  but,  as  I  had  an  opportunity  to  examine,  by  analyfis,  a  portion  of. 
the  fame  earth  on  which  Mr.  Wedgwood  made  his  experiments,  and  as  I  received  it  from 

Si* 


8o  Anal-jft}  if  Sydney  Earih.-^Artificial  Magndt. 

Sir  Jofepli  Banks,  the  fame  gentleman  who  had  furnilhed  Mr.  Wedgwood  with  it,  no 
fufpicion  can  be  entertained  about  its  identity. 

Some  of  the  esperiments  which  I  have  related,  and  which  prove  that  fome  of  the  finer 
earthy  pavticles  remained  fufpended  in  the  concentrated  muriatic  acid,  and  were  precipi- 
tated when  the  acid  was  diluted  with  water,  appear  in  fome  meafure  to  account  for  the 
miftake  which  has  been  made,  in  fuppofing  that  a  primitive  earth,  before  unknown,  was 
prefent ;  but  this  alone  will  not  account  for  many  of  the  other  properties  mentioned  by  Mr. 
Wedgwood  :  fuch  as, 

lit.  The  repeated  and  excluGve  folubility  in  the  muriatic  acid,  and  fubfequcnt  precipi- 
tation by  water. 

2dly.  The  butyraceous  mafs  which  was  formed  by  evaporation.    And 

3dly.  The  degree  of  fufibility  of  the  precipitated  earth. 

Thefe,  indeed,  I  can  by  no  means  explain,  but  by  fuppofing  that  the  acids  ufed  by  Mr. 
Wedgwood  were  impure.  This  fuppofition  appears  to  be  corroborated  by  a  palTage  in  Mr. 
Wedgwood's  paper,  where  he  fays,  "  Here  the  Pruffian  lixivium,  in  whatever  quantity  it 
was  added,  occafioned  no  precipitation  at  all,  (only  the  ufual  blueiftinefs  arifing  from  the 
iron  always  found  mthe  common  acids.'')*  Now  if  (as  it  feems  from  this  expreffion)  Mr. 
Wedgwood  employed  the  common  acids  of  the  (hops,  without  having  previoully  examined 
and  purified  them,  all  certainty  of  analyfis  muft  fall,  as  the  impurity  of  fuch  acids  is  well 
known  to  every  praftical  chemiftf  :  but  whether  this  was  thecaufe,  or  not,  of  the  effeSs 
defcribed  by  Mr.  Wedgwood,  I  do  not  hefitate  to  afTert,  that  the  mineral  which  has  been 
examined  does  not  contain  any  primitive  earth,  or  fubflance  poflefling  the  properties  afcri- 
bed  to  it,  and  confequently,  that  the  Sydneian  genus,  in  future,  muft  be  omitted  in  the 
mineral  fyftem. 


VI. 

The  Method  of  making  Jlrong  Artificial  Magnets.     By  M.  CouloMBX. 

1.  SHALL  here  prefent  the  methods  which  I  have  found  fuccefsful  in  conftru£ling  artificial 
magnets  of  very  great  force  at  a  moderate  expence.  *  *  *  *  When  a  fteel  rod  or  plate 
is  required  to  be  rendered  magnetic,  and  two  bars  are  ufed  for  this  purpofe,  it  is  obvious 
that  it  muft  be  of  advantage  to  caufe  the  poles  of  thefe  bars  to  act  in  conjunftion  with 
each  other.  This  has  given  rife  to  the  method  of  the  double  touch.  Fig.  i,  Plate  IV. 
fhows  the  former  practice  of  this  method.  If  the  bar  n  s  be  required  to  be  impregnated, 
the  two  bars  SN,  S'N',  were  placed  vertically  at  the  diftance  of  feven  or  eight  lines  from 

*  Philofophical  Tranfaftions,  vol.  Ixxx.  partii.  p.  313. 

+  It  appears  from  Wedgwood's  paper,  that  nearly  one  fifth  part  of  the  mineral  was  taken  up  by  muriatic 
acid,  and  that  his  folution  was  reckoned  to  have  about  fix  grains  of  the  foluble  matter  to  three  ounces  of  the  acid. 
From  the  experimental  procefs  of  boiling,  it  feems  probable  that  the  aftual  quantity  of  acid  made  ufc  of,  bore 
an  higher  proportion  to  the  matter  taken  up.  If  we  admit  the  fuppofition  of  impurity  in  Wedgwood's  acid,  the 
quantity  of  matter  precipitable  by  water  was  probably  lefs  than  two  grains  in  the  ounce  :  and  after  rejcfting  the 
Sydneian  earth,  as  we  undoubtedly  muft,  it  may  perhaps  be  an  objeft  worthy  of  enquiry  to  determine  what 
that  fubftance  was  in  which  Wedgwood  obferved  the  peculiar  properties  related  in  his  paper.    N. 

X  Journal  dc  Pbyfique,  xliii. 

each 


Improvement  </fthe  Douhle  Magnetic  Touch,  ]}| 

each  other,  mg^e  or  lefs  according  to  their  force  j  the  points  S  and  S'rcprefenting  the 
fouth,  and  the  points  N,  N'  the  north  poles.  In  this  fituation  the  two  i)ars  were  moved 
from  one  end  to  the  other  of  the  bar  n  s. 

M.  ^pinus  has  remarked,  that  in  this  method  the  centre  of  aftion  of  the  two  magnets 
NS,  N'S'  being  neceflarily  placed  at  fome  diftance  from  their  extremities  at  the  point  u 
for  example,  the  a£lion  on  the  points  of  the  bar  n  s  comprehended  between  the  two  bars 
is  made  very  obliquely,  and  confequently  does  not  communicate  as  much  magnetifra 
a5  the  fubje£l  is  capable  of  receiving.  Whence,  inftead  of  placing  the  two  bars  upright  in 
this  operation,  M.  ^pinus  advifes  that  they  (hould  be  inclined,  as  in  fig.  2  ;  and  in  this 
pofuion  moved  from  one  end  of  the  bar  to  the  other. 

I  have,  in  fa£t,  found  by  the  magnetic  balance  defcribed  at  the  beginning  of  this  me- 
moir*, that  the  method  of  M.  ^pinus  is  preferable  to  the  other;  but  I  have  alfo  obferved, 
that  it  does  not  give  the  needles  the  pcrfe£l  faturation  of  magnetifm,  and  that  frequently 
when  the  needle  is  of  confiderable  length,  feveral  poles  are  formed  on  the  intermediate  parts, 
the  action  of  which  is  indeed  fmall,  but  neverthelefs  perceptible.  I  attribute  thefe  to 
the  particular  adtion  of  each  magnet,  which  tends  to  produce  on  the  points  pafled  over  by 
the  magnets  an  efFctl  contrary  to  that  which  is  defired.  In  our  figure  2,  the  pole  S  for 
example  being  placed  upon  the  needle,  tends  at  the  fame  time  to  give  to  the  point  q,  which 
is  placed  under  the  bar,  the  fame  kind  of  magnetifra  as  at  the  point  u  ;  that  is  to  fay, 
on  the  hypothefis  of  two  magnctical  fluids  capable  of  moving  towards  the  extremities  of 
the  needle,  if  the  point  u  be  drawn  towards  the  point  n,  the  point  q  which  is  near  it  will  be 
drawn  towards  the  point  s,  after  this  point  q  fhall  have  been  palled  by  both  magnets.  In 
my  hypothefis,  in  which  the  magnetic  fluid  is  not  capable  of  moving,  except  in  the  inte- 
grant parts,  the  molecules  u  and  q,  which  are  near  each  other,  tend  to  become  magnetized 
in  oppofite  dire£l;Ions;  and  mud  produce  a  diminution  of  magnetifm  towards  the  extremi- 
ties of  the  needle,  where  the  magnetic  fluid  muft  be  moll  condenfed ;  a  circumftance 
which  may  produce  feveral  poles  in  very  long  needles,  as  Is  proved  by  experience.  This 
obfervatlon,  which  neceflarily  refults  from  the  accurate  meafures  afforded  by  my  experi- 
ments, obliged  me  to  depart  from  the  method  of  M.  ^pinus.  The  following  is  that 
which,  after  various  trials,  has  proved  by  the  magnetic  balance  to  be  the  moft  advantageous.  ' 

In  my  operation  I  ufe  four  very  flrong  magnets  impregnated  by  a  firft  procefs,  which  I"" 
rtiall  prefently  defcrlbe.  I  place  my  two  ftrongeft  magnets  (fig.  3.)  NS,  NS,  on  an  horizon-  ^ 
tal  plane  in  one  right  line,  at  fuch  a  diftance  that  they  may  be  a  few  lines  nearer  to  each 
other,  than  the  length  of  the  needle  n  s  intended  to  be  magnetized.  I  afterwards  take  the 
two  magnets  N'  S'i  and  inclining  them  as  in  the  method  of  ^pinus,  I  place  them  firft  on 
the  middle  of  the  needle,  or  with  their  poles  nearly  in  contaft.  I  then  draw  each  magnet, 
without  changing  its  inclination,  to  the  extremity  of  the  needle,  and  repeat  this  operation 
five  or  fix  times  on  each  face  of  the  needle.  It  is  clear  that  in  this  operation  the  poles  of 
the  needle  n  s  remain  fixed  and  invariable  at  the  extremities  of  the  needle,  by  means  of 
the  two  ftrong  magnets  NS  on  which  it  refts.     The  efi^eft  produced  by  thefe  can  only  be 

*  The  excellent  and  well  known  method  of  Coulomb  of  meafuring  the  forces  of  eleSricity  and  magnetifm, 
is  by  fufpeoding  an  horizontal  lever  or  bar  by  a  fine  wire  at  the  point  of  fufpenfion  ;  which  bar  being  turned 
caufes  the  wire  by  its  torfion  to  exert  a  determinable  force  againft  the  afticn  intended  to  be  meafured.     N. 

Vol.  II.— May  179?.  M  augmented 


82  Method  of  exciting  Mngiietlfm. 

augmented  by  the  aclion  of  the  two.fupenor  magtieis,  which'  concur  In  magi.^tizing  all  the 
particles  of  the  neeJle  in  the  fame  dh-eftioh.    '        - 

As  the  needle  n  s,  placed  between  the  two  large  magnets  ih  the  preceding  operation, 
acquires  bythe  joint  adtion  of  the  four  bars  a  degree  of  polarity  which  is  more  than  it  can 
preferve  when  feparated  from  them,  it  follows  that  at  the  mofheiit  of  this  feparation  the 
needle  lofes  part  of  the  magnetifm  it  derived  from  thofe  forces,  and  that  its  magnctifm  di- 
miniliies  Until  the' inagnetic  a£lion  of  the  whole  needle  on  each  of  its  parts  is  in  equilibrio 
■with'the  coercive  force.  Hence,  upon  feparating  the  needle  from- the  magnets,  it  is  found 
to  be  faturated  with  magnetifirt. 

I  have  found  likewife,  that  in  this  method  of  magnetizing,  there  is  a  greater  certainty  of  ; 
giving  to  both  furfaces  of  needles,  intended  to  determine  the  magnetic  meridian,  an  equal 
degree  of  magnetifm  J  a  circumftance  deferving  of  the  greatefl  attention  in  the  conftruc- 
tion  of  compafles,  if  the  needle  be  fufpended  with  its  broadefl  furface  parallel  to  the  ho- 
rizon. 

The  ConfruBion  of  Artificial  Alagrit'fs. 

I  TAKE  fig.  4.  thirty  bars  of  (leel  hardened  and  tempered  to  the  temper  of  a  fpring  *  5  or 
6  Uneshroadi.a  or  3  lines  thick,  and  36  inches  long.  The  blades  of  fencing  foils,  fuch  as 
are  found  in  the  fliops,  make  pretty  good  magnets.  Englifli  .fheet  fteel  f  (la  tole  d'acicr 
d'Angleterre)  cut  uito  pieces  one  inch  wide,  hardened  and  lowered  to  fpring  temper,  is  pre- 
ferable. When  each  compound  magnet  is  to  contain  no  more  than  15  or  20  pounds  of 
fteel,  it  isfufficient  to  make  the  bars  30  or  36  inches  long. 

I  magnetize  each  "bar  fingly,  according  to  the  method  already  defcribed.  I  then  take  two 
reflangular  parallelopipedons  of  very  foft  iron,  v.'dl  polilhed,  6  inches  in  length,  between  20 
and  24  lines  broad,  and  10  or  12  lines  thickj  :  with  thefe  two  parallelopipedons  reprefented 
fig.  4.  at  N  andS,  I  form  the  armor  of  my  inagnetby  enveloping  one  extremity  of  each  pa- 
rallelopipedon with  a  ftratum  of  my  magnetic  bars,  fo  that  the  extremities  of  the  parallflo- 
pipedons  may  projeil  beyond  the  extremities  of  the  bars  20  or  24  lines,  and  the  other  part 
may  be  enveloped  by  the  ends  of  the  fet  of  bars.  On  this  firft  layer  of  fteel  bars  of  3  or  4  lines 
thick,  I  place  a  fecond  which  Is  tliree  inches  (horter  than  the  firft,  fo  that  the  firft  projeds 
beyond  the  fecond  18  lines  on  each  fide.  The  whole  is  fecured  at  the  ends  by  two  binding 
pieces  of  copper,  which  prefs  the  bars  clofe  tpgefher,  and  prevent  the  armor  from  efcaping. 

Ftg.  4.  reprefents  two  artificial  inagnets  compofed  according 'to  the  method  juft  de- 
fcribed. N  and  S  are  the  extremities  of  the  two  Iron  parallelopipedons.  The  two  other 
extremities  are  inclofed  by  the  bars,     liach  magnet  thus  compounded  is  folldly  conne£ted 

•  By  other  experiments,  the  author  has  afcertained  that  the  mag.ietifin  acquired  by  fteel  is  leaft  when  it  ij 
either  ablbhalely  hard  or  annealed  by  a  white  heat,  and  grcatcft  whcw'it  has  licen  hardened  and  annealed  by  a 
very  obfcure  red  heat ;  from  which  middle  term  it  dimipiflies  eithcs  Wayv,Avlmtlicii  the  bar  be  harder  or 
Ibfter.     N.  ,  :     ■  ,  ' .  v.;,r     i:::  ''      ;.  : 

f  We  have  two  fons  at  leaft  in  thel-ondon  market.     The  commoa  fort  is  fol^  reoil  at.fid.  or  7d.  per  Ih. 

the  finer,  under  the  name  of  caft-fteet  (vvhiLh  I  fuppofe  it  to  be)  is  ("old  at  one  fiiilliiig  per  lb.  and  deferves  its 

price.    I  have  noc  been  able  to  procure  fiicet  fteel  thicker  than  i-f:th  of  an  inch.    N.  ' 

I  All  the  weights  and  meafurcs  in  this  paper  are  French  ;  but  as  extreme  prcciflon  is  no  where  implied,  it 

was  unnecefl'ary  to  reduce  them.     N.  . 

3  together 


Magneiifnt.'^-^ Separation  of  iilctgnefta  frm  Clay.  ;l^ 

together  by  tlie  copper  pieces  marked  a,  b,  z'-,  b'.     The  pieces  of  contaft  A,  R,  join  the 
■op.pofite  poles  of  the  ri>agnets. 

Experience  has  fliewn  me,  that  with  an  apparatus  of  this  form,  each  part  weighing  15  or 
20lb.  a  force  of  80  or  100  pounds  will  be  required  to  feparate  the  pieces  of  Conta(Sl;  and 
that  when  an  ordinary  needle  of  the  compafs  ^s  placed  on  the  two-  extremities  of  our  two 
compound  bars,  fig.  4J. they  become  magnetized  to  faturation  without  its  being  necefTary 
to  rub  them  with  the  u-pper  pair  of 'magnets.'  It  is  fcarcely  neceflary  to  obferve,  that  when 
magnets  of  greater  force  are  defired,  it  is  neceffary,  in  proportion  as  the  number  of  bars  is 
'increafed,  to  augment  t-heirfeivgthatfo,' and  the  dimenfions  of  the  parallelopipedonsof  iron 
■which  ferve  for  the  armor.  It  would  be  eafy  to  afcertain  the  different  dimenfions  which 
the  magnets  ought  to  have,  in  a  manner  fulEciently  accurate  for  praclice,  from  the  laws  of 
magnetifm,  and  the  pofition  ofthe  centre  of  a£lioni  df  t-he  bars  of  ft.eel,.of  different  lengths 
and  thiclcnefs,  which  we  have  explained  in  the  "courfe  of  this  memoir. 


On  the  Separation  9f  Argillaceous  Earth  from  Magtiefta.     By  Mr*  F.jfccUM' . . 
To   Mr.    N  I,C Jft.OI^S.O.N. 

SIR,  ...    ■    '  .;;;;  ;  v" ;  ^;  ■';      . 

JL  H  E  feparation  6f"arg{i[laceous'  e^^h  from  magnefia,  when  both  are  combined  in  one 
fubftance,  as  is  very  often  the  cafe  in  mineral  bodies,  has  been  hitTierto  confidered  as 
one  of  the  moft  diflficult  operations  in  the  whole  analyfis  of  artificial  and  natural  com- 
pounds. The  experimental  chemift,  who  is  pra£tically  employed  in  the  invelligation  of 
mineral  fubftances,  mull  be  fenfible  of  the  difficulties  which  unavoidably  accompany  the 
prefent  method  of  operation ;  and  muft  likewife  allow,  that  notvvithftanding  the  utmoft 
care,  accuracy  and  (kill,  it  is  fcarcely  poffible  tp  avoid  uncertainty  in  his  conclufions  and 
refults.  For  thefe  reafons,  I  beg  leave  to  obferve,  that  the  above  objeft  may  be  accom- 
pliflied  to  the  utmoft  precifion  in  the  following  manner  :  "When  both  thefe  earths  are  in 
a  folution  of  muriatic  acid  in  a  perfeflly  faturated  ftate,  the  argillaceous  earth  may  be 
totally  feparated  by  means  of  carbonate  of  ammoniac;  as  this  will  only  difengage  that  earth, 
and  the  magnefia  will  be  retained  in  folution ;  which  may  then  be  feparated  by  adding  fo- 
lution of  pure  potalh  or  foda  to  the  remaining  fluid. 

1  am,  Sir,  your  humble  fervant, 
Haytnarhi,  No.  17.  FREDERICK  ACCUM. 


M  2  VIII.  Exiraas 


^  Rotatioti  of  the  Earth. — Proje^ihs,  ^c. 

VIII. 

ExlraHs  from  the  Manufcr'tpts  if  Leonard  de  Vinci.  With  Remarks,  by  J.  B.  V£NTVRi, 
',     '       ProfeJJbr  of  Natural  Philofophy  at  Modena,  Member  of  the  In/iiluie  of  Bologna  *. 

I.  V-/N  the  defcent  of  heavy  bodies  combined  with  the  rotation  of  the  earth,  De  Vinci 
(hdws  by  a  figure,  that  a  body  let  fall  from  an  emhience  will  continue  perpendicularly  over 
the  f.ime  fpot,  riotwithftanding  the  rotation  of  the  earth,  and  confequently  infer^  that 
it  will  defcribe  a  fpii-al  line.    (It  is  an  ellipfis.) 

It.  was  at  the  commencement  of  the  j6th  century  that  the  works  of  Nicolas  de  Cufa 
tpfete-  printed,  in  which  that  author  endeavoured  to  renew  the  ancient  dodlrine  of  the 
motion  of  the  earth,  though  in  a  confufed  and  metaphyfical  method.  1  he  writing  of  de 
Vinci  is  nearly  of  the  year  1510,  and  fliows  that  this  notion  was  in  a  ftate  of  difcuffion  in 
the  minds  of  difcerning  men  before  the  time  of  Copernicus.  It  has  been  aflerted,  that 
Rcgiomontanus  fupported  this  do£lrine  j  but  he  oppofes  it  direiSlly  in  a  writing  prcferved 
by  Schoner,  and  in  his  commentaries  on  the  Almageft  f.  The  doclrine  of  tlie  motion  of 
the  earth  was  publicly  maintained  for  the  firft  time  at  Rome,  in  1533,  by  Widmanftat|:, 
who  affirmed  that  he  had  learned  it  from  Copernicus.  The  work  of  this  lad  did  not 
appear  till  1543.  Vinci  was  the  only  man  at  that  time  who  was  fufficiently  acquainted 
with  mechanics  to  apply  the  theory  of  combined  motion  to  the  fall  of  heavy  bodies,  an 
application  of  which  Uie  honour  was  afllimed  by  Gaflendi  in  the  laft  century§.  In  this 
ftate  the  opinion  of  philofophers  remained,  until  D'Alembert  demonllrated,  that  heavy  bo- 
dies projcfled  towards  the  zenith  ought  not  to  fall  exaiSlly  at  the  place  wlience  they  ftt 
omt.  A  fimilar  idea  has  been  taken  up  in  my  country.  The  .tower  Afinelli  in  Bologna 
is  about  three  hundred  feet  high.  A  ball  exaftly  round  being  let  fall  from  this  height  to 
the  earth,  ought  to  deviate  nearly  fix  lines  from  the  perpendicular.  J.  B.  GuUielmini  made 
the  experiment  in  1792  with  great  care.  He  could  not  avoid  fome  aberrations,  of  which 
the  mean  refult,  however,  confirmed  the  truth  of  a  izSt  which  had  before  been  demon- 
ftrated  by  aftronomy  and  mechanics  ||. 

II.  Concerning  the  earth  divided  into  fragments. — L.  de  Vinci  affirms,  that  if  the  earth 
were  curt  into  fragments,  and  difperfed  through  the  furrounding  fpace,  a  fingle  fragment 
being  let  fall  would  be  carried  to  the  common  centre,  which  it  would  pafs  to  a  nearly 
equal  diflance  on  the  oppofite  fide,  and  return  again  nearly  to  the  place  whence  it  fet  out ; 
and  in  this  way  the  vibrations  would  continue  : — that  if  all  the  fragments  were  fuftercd  to 
fall  at  different  times,  they  would  meet^  ftrike,  and  break  each  other,  ,apd  a  tumultuous 

"*  From  the  "  Effhi  fur  les  Ouvrages  Phyfico-Mathcmatiques  de  Leonard  dc  Vinci, ''  of  which  notice  is  taken 
in  Philof.  Journal,  I.  599'.  1  have  abridged  the  palTageS  in  many  inftances.  All  the  remarks  in  the  text  are 
by  Proftdor  Venturi. 

+  Schbii'eH  Opera,  pars  fecunda,  cart.  127.     Rcgiomoutan.  in  Almageftum,  1.  p.  concluf.  5. 

J  Marini  Anchiatri  Pontificii,  torn.  2,  pag.  351. 

§  De  motu  impreffo  amotore  tranflato.  Paris  1642. 

H  De  diurno  terrae  motu  expcrimentis  confirmato.  Bonon.  1792. — An  experiment  of  this  nature  was  propofej 
to  the  Royal  Society,  and  a  difcourfe  read  thereon  by  Robert  Hooke,  who  inferreii  that  the  ball  would  in  our 
latitude  fall  to  the  S.  E.  This,  on  trial  about  December  1679,  proved  to  be  the  cafe.  See  Ward's  Lives  of 
the  Greiham  Prcfeffors,  p.  184.    N. 

::  ;>;  commotion 


Theory  of  the  Earth,  ^c.  85 

commotion  would  be  produced  in  the  atmofphere,  which  would  conliriuc  for  years,  until 
all  the  parts  were  united  about  the  common  centre*. 

III.  Concerning  the  earth  and  the  moon. — That  the  earth  is  a  ftar  ;  that  the  fcintillation 
of  the  flars  is  an  aiFedlion  of  the  eye  +;  that  the  earth  performs  the  fame  office  of  illumi- 
nation to  the  moon,  as  the  moon  to  the  earth,  but  with  contrary  phafea  ;  that  the  earth  in 
lunar  eclipfes  does  not  receive  light  by  reflection  from  the  moon,  mr  the  moon  from  the 
earth  in  folar  eclipfes ;  that  the  obfcure  illumination  of  the  dark  part  of  the  moon  at  the 
beginning  of  the  firft  and  end  of  tlie  lafl  quarters  is  produced  by  rcfle£lion  of  folar  light 
from  the  earth. 

IV.  On  the  adlion  of  the  fun  upon  the  ocean. — Our  author  affirms  that  the  heat  of  the 
fun  caufes  the  waters  of  the  fea  to  rife  in  an  eminence  beneath  the  equator,  from  which 
tliey  flow  on  all  fides,  as  may  be  obferved  in  water  heated  over  a  fire  ;  and  that  the  aqueous 
eminence  following  the  fun  in  the  diurnal  motion  is  carried  through  about  a  thoufand 
miles  per  hour. 

De  Vinci  has  here  applied  the  fame  principle  to  the  waters  of  the  ocean,  as  Halley  has 
fince  ufed  to  explain  the  trade  winds  in  the  atmofphere  J. 

V.  The  ancient  Hate  of  the  earth. — When  the  water  of  rivers  depofited  its  mud  upon  the 
marine  animals  living  near  the  fliore,  this  mud  imprefled  itfelf  upon  the  animals  thera- 
felves.  When  the  fea  afterwards  retired,  this  mud  became  petrified  all  round,  and  within 
the  fliells  of  teftacea  which  it  had  penetrated.  Thefe  are  found  in  various  places ;  and 
moft  of  the  fliell-filh  petrified  in  the  mountains  have  their  fliells  entire,  particularly  thofe 
of  the  greatell  age  and  hardnefs.  In  anfwer  to  a  fuppofed  objedion,  that  the  influence  of 
the  liars  may  have  formed  thefe  fliells  in  the  mountains,  the  author  requires  to  be  Ihewn 
any  place  where  this  operation  of  the  flars  is  in  aftual  progrefs  to  form  fhells  of  difl^erent 
ages  and  fpecies  in  the  fame  place.  And  how  upon  that  fyftem  it  can  be  explained  why 
the  gravel  has  become  indurated  in  ftrata  at  different  heights  in  the  mountains.  This 
gravel,  continues  he,  has  been  tranfported  thither  from  various  places  by  the  currents  of 
rivers.  It  was  formed  of  fragments  of  ftone,  of  which  the  corners  have  been  worn  down 
by  the  frictions,  blows,  and  falls  they  have  undergone  in  the  water  which  rolled  them  to 
their  prefent  fituation.  And  how  can  this  fyftem  explain  the  great  number  of  different 
kinds  of  leaves  bedded  in  ftone  near  the  tops  of  mountains  ?  and  the  Alga,  a  marine 
plant,  intermixed  with  fliells  and  fand,  and  petrified  in  a  mafs  with  fea  crabs  broken  and 
confounded  with  the  fame  fliells. 

*  In  thisfeftion  it  is  evident,  as  ProfelTor  Venturi  remarks,  that  our  author  has  a  clear  comprehenfion  of  the 
inertia  of  matter.  Another  ftep  in  the  procefs  of  rcafoning  would  have  given  a  revolution,  to  his  falling  frag» 
ment,  in  an  apprq>riate  orbit.  The  vibration  of  a  body  in  a  cavity  through  the  centre  of  the  earth  to  the  anti, 
podes,  and  the  retention  of  the  moon  in  its  orbit  by  the  combination  of  the  projeft'.le  and  gravitating  forces 
are  ftated  in  a  palTage  of  fome  length  by  Plutarch,  in  his  crem(e  De  flat  t'tis  fhilofopherum,  as  I  well  remsmbtr, 
but  have  not  the  work  at  hand  to  quote.     N. 

f  On  this  fubjeft  it  may  be  remarked  in  favour  of  fcintillation  being  a  confequcnce  of  the  irregular  denfity 
of  the  air,  and  not  an  affeftion  of  the  eye,  i.  That  itii  lefs  on  lofty  mountains,  and  countries  where  the  air  is  al- 
moft  conftamly  ferenc.  a.  That  in  the  fame  ftar  it  is  lefs,  the  greater  the  altitude.  Andj.  That,  contrary  to^  gcf. 
iieral  obfcrvation,  it  may  be  obferved  through  a  tclefcope,  provided  the  difc  of  the  ftar  be  eniar^^ed  hj  deran- 
ging the  focal  adjuftmcnt.     N. 

+  And  very  lately  again  applied  to  the  fe»  by  Count  Rumford.    Phibf.  Jourual,  I.  573.     N. 

Thc^ 


86  Theory  of  the  Earth. 

The  fea  changes  the  equilibrium  of  the  earth.  The  oyflers  and  other  (hells  which  ase 
formed  in  the  mud  of  the  fea,  atteft  the  change  which  the  earth  has  undergone  about  the 
centre  of  the  elements.  Large  rivers  always  wear  away  the  earth  which  they  detach  by 
friftion  from  their  beds.  This  corrofion  difcovers  to  us  many  banks  of  fhells  heaped  to- 
gether in  different  layers,  and  the  fnell-fiih  have  lived  in  the  fame  place  when  the  waters 
of  the  fea  covered  them.  Thcfe  banks  in  the  courfe  of  time  have  been  covered  by  other  • 
ftrata  of  mud  of  different  thickneffcs;  fo  that  the  fiiells  have  been  bedded  in  the  mud 
heaped  above  them  in  fuch  a  manner  as  to  rife  above  the  furface  of  tlie  water.  At  the 
prefent  time  thefe  beds  are  at  the  height  of  hills  and  mountains,  and  the  rivers,  by  wear- 
ing them  away,  difcover  the  ftrata  of  fhells  at  their  fummits.  Here  then  is  a  portion  of 
the  earth  become  lighter,  which  continually  rifes  while  the  oppofite  parts  approach 
nearer  and  nearer  to  the  centre  of  the  earth ;  and  that  which  was  formeriy  the  bottom  of 
the  fea  is  now  become  the  fummits  of  the  mountains. 

When  a  river  forms  banks  of  mud  or  fand,  and  afterwards  quits  them,  the  water  that 
runs  fvom  thefe  maffes  flie  ws  the  manner  in  which  the  mountains  and  valleys  may  by  degrees 
be  formed  in  a  foil  riGng  from  the  bottom  of  the  fea,  though  this  ground  might  at  firft 
have  been  nearly  plain  and  uniform.  The  water  which  flows  from  this  land  elevated  from 
the  bottom  of  the  ocean,  begins  to  form  currents  at  the  lower  parts,  and  excavates  the  beds 
of  rivulets  which  receive  the  fluid  from  the  neighbouring  parts.  The  rivulets,  afterwards 
fed  by  the  rain  waters^  become  broader  and  deeper  every  day,  and  are  converted  into  tor- 
rents paffmg  through  ravines :  they  unite  into  rivers,  and  by  continually  wearing  away 
their  banks  they  convert  the  land  between  them  into  mountains.  The  rains  have  in- 
ceffantly  fwept  and  degraded  thefe  mountains.  The  elevated  rock  remains  furrounded  by 
the  air ;  the  earth  of  the  fummit  and  its  fides  has  defcended  to  its  bafc,  and,  by  raifing 
the  bottom  of  the  fea  which  furrounded  that  bafe  itfelf,  has  forced  it  to  retire  to  a 
diftance. 

Vinci  is  here  the  firft  among  modern  philofophers  who  maintained  that  the  greateft 
part  of  the  continents  have  formerly  exifted  at  the  bottom  of  the  fea.  We  cannot  reje£l 
this  do£lrine,  which  is  proved  by  every  geological  obfcrvation ;  but  we  do  not  yet  difcern 
the  means  of  reconciling  the  fucceffive  tranfportation  of  the  fea,  on  the  furface  of  the  globe, 
with  the  laws  of  gravitation.  L.  de  Vinci  offers  an  explanation  which  may  well  deferve 
fome  examination.  It  is  different  from  the  opinion  of  Bernier,  wlio  has  afcribed  a  motion 
to  the  centre  of  gravity,  without  changing  the  arrangement  of  the  folid  parts  of  the  earth. 
But  the  profound  geometer,  who  has  lately  traced  the  fyftem  of  the  world,  agrees  that  the 
obfervations  of  Bouguer  and  Mafkelyne  on  the  attra£lion  of  mountains  do  not  entirely  de- 
termine the  denfity  of  the  Interior  part  of  the  earth  *.  "We  may  therefore  ftill  fuppofe  at 
prefent,  as  Vinci  does  in  his  writings,  that  the  fluid  mafs  in  our  globe  is  equal,  or  may  be 
even  greater  than  the  folid  portion  :  or,  if  this  hypothefis  be  not  admitted,  it  will  be  fuflS- 
cient  if  we  fuppofe  that  there  are  feveral  detached  folid  maffes  in  our  globe,  fo  that  each 
continent  may  be  conCdered  as  a  fmall  part  of  the  total  mafs  of  the  earth.  Whence  the 
mafs  of  matter  tranfported  by  the  rain  during  the  lapfe  of  centuries  from  the  fummits  of 
mountains  to  the  bottom  of  the  fea,  may  be  fufficiently  great,  in  proportion  to  the  mafs  of 
each  continent,  to  caufe  thofe  coiitinents  to  emerge  more  and  more  above  the  furface,  or 

*  Expofitiori  du  Syfttme  du  Monde,  par  P.  S.  La  Place. 

to 


'Theotyef  the  Earth,— Combujlm.  87, 

to  caufe  them  to  rife  on  one  fide,  while  they  become  immerfed  on  the  other,  until  at  length 
fome  great  fliock  may  reverfe  them  entirely,  or  caufe  fome  new  mafles  to  rife  from  the 
bottom  of  the  fca.  This  will  be,  it  may  be  faid,  an  hypothetical  notion  ;  but  it  is  a  notion 
wliich  flicws  that  dc  Vinci  contemplated  ihe  caufe  of  the  phenomenon  in  a  way  fufficier.ly 
agreeable  to  the  raechanifm  of  gravitation.  No  philofopher  Cncc  his  time  has  yet  thought 
of  a  more  fatisfntflory  explanation  *.  . 

VI.  Concerning  flame  and  air. — Where  flame  is  produced,  a  current  of  air  takes  place  , 
around,  -which  is  neceffary  to  preferve  arid  augment  the  flame.  The  ftronger  the  motion  of 
the  air,  the  more  brilliant  the  flame  and  the  greater  the  heat.  Fire  inceiTantly  deftroys  the 
air  which  nourifhes  it  ;  and  it  would  produce  a  vacuum,  if  other  air  did  not  rufli  in  and 
fill  it.  When  the  air  is  not  in  a  ftate  proper  to  receive  the  flame,  neither  flame  nor  any  tcr- 
reftrial  or  aerial  animal  can  live.     No  animal  can  live  in  a  place  where  flame  cannot  live. 

Smoke  is  produced  in  the  centre  of  the  flame  of  a  candle,  hecaufe  the  air  which  enters 
into  the  compofition  of  the"  flame  cannot  penetrate  to  its  interior  part.-     It-  is  arrelted  at  the 
furface  of  the  flame,  which  it  condenfes  ;  by  becoming  die  aliment  of  the  flame  it  is  tranf-, 
formed  into  it,  and  leaves  a  void  fpace,  which  is  fucceifively  filled  by  other  air. 
,     ♦  I  mull  confcfs  that  the  difficulties  of  this  theory  do  not  apjxar  to  be  removei  cither  by  the  observations  of 
the  author  or  his  learned  comir.ci.taror.     I  apprehend  that  the  hypothtfis  requires  or  affertt,  that  I'ome  natural 
procefs  flwuld  take  place  to  raife  the  land  above  the  furface  of  the  Water,  which  was  originallv  beneatli  that 
furface  ;  and  the  alTiinied  ptincijjle  is,  that  it  iliall  rife  becaufe  lighter  than  an  eijaalmafi  of  water.    The  rpVcific 
giavitics  of  miniral  fubftancts  are  totally  repugnant  to  this  notion  of  floating  continents,  unlefs  we  fuppol'ethL-m 
to  be  hoUow,  which  is  by  no  means  rendered  prob-able  to  the  required  degree.     Neither  do  we  knoyv  of  any  fafts  • 
which  (hew  that  the  longitudes  and  latitudes  of  places  ott  the  fevcrai  contments  are  liable  to  change,  as  mult  bft 
the  cafe  if  each' continent  were  a  feparate  mafs  capable  of  librating  (Jn  a  comparatively  narrow  face  of  I'upport, 
as  fettns  to  he  implitd  in  one  pr.rt  cf  Profcilor  \'<.nturi's  ani;otation.  It  appears  however  to  be  well  afccrtaincd, 
that  the  fca  has  formerly  furmounted  the  level  of  high,  aod  perhaps  the.  higheft  mountains  ;  and  from  the  re-' 
gularity  of  difpofition   which  in   many  inftances  is  obfervablc  (I'hilof.  Journal,  I.  X21.)  it  may  be  doubted 
whether  the  fliock  of  a  comet  (Philof.  Journal,  II.  41.)  and  the  fuppofed  change  6f  the  earth's -axis  of  rota-' 
tion  are  fufficient  to  account  for  its  fubfecjui-nt  deprcilion.     I  think  it"is  fcarccly  difputable,  that  the  whole  of 
the  folid  mafs  of  the  earth  is  connefted  together,   and  that  the  fluid  portion  occupies  the  ca\itics  to  which  it 
can  have  accefs  in  this  folid.  -  If  we  fufipofe  tl)e  globe  of  the  earth  to  have  been  formerly  enveloped 'by  a  fea, 
whofc  furface  was  between  two  and  three  niiles  higher  than  the  furface  of  theprefcnt  ocean,  or  even  much 
lefs  elevated,  the  finiple  enquiry  will  be,  what  has  become  of  it  ?    It, cannot  have  affumed  the  elafti'c  ftate  ;  ■  for 
we  know  the  medium  weight  of  the  atmofphere,  which  correfponds  with  little  more  than  a  (hell  of  water  co- 
vering the  earth  to  the  depth  of  about  thirty-three  feet.     We  are  therefore  led  to  the  following  objefts  of  in- 
veftigation  :   i.   Is  the  earth  folid  throughout,  or  does  it  aflford  natural  cavities  into  which  the  water  may,  in 
the  courfe  of  ages,  have  found  its  way  ?   2.  As  a  vtry  large  part  of  the  prefent  furface  of  the  earth  has  been 
thrown   up  by  the  chemical  procefs  of  volcanic  combuftion,  and  thefe  procelfes  muft  have  left  cavities  beneath 
the  furface,  it  may  become  a  matter  of  computation  to  determine  the  folid  contents  of  volcanic  product  above 
the  prefent  level  of  the  fea,  in  order  to  afcertain  the  quantity  of  depreflion  the  fca  would  have  fuffered  on  the 
fuppofit'ion  of  its  having  fooner  or  later  flowed  into  thofe  cavities.      3.  If,  upon  careful  enquiry  into  thefe  fafts,    . 
it  (hould  be  afcertaincd,  or  rendered  highly  probable,  that  the  primitive  fea.has  in  a  great  meafure  difappeared 
by  flowing  into  cavities  in  the  folid  mafs  of  the  earth,  would  not  the  globe  of  the  moon  afford  an  inftance  in    . 
confirmation  of  fucK  a  procefs  ?  For  the  obfcure  parts  of  that  globe  which  were  at  firft  thought  to  be  feas  are 
oblervcd  to  be  cavities,  probably  the  beds  of  ancient  feas.     It  feems  likely  that  the  component  parts  of  the 
moon  (whatever  may  be  thofe  of  the. other  planets)  are  nearly  the.iime  as  of  the  earth.     Yet  its  atmofphere 
as  well  as  itsfurface  indicates  a  great  warit.if  not  the  tdtallbfence  of  tvater.    Has  it  required  lefs  time  for  the 
lunar  fea  to  he  abforbed  ? — Much  more  might  be  faid  :  but  on  an  objeft  wlierc  fafls  arc  wanting,  and  con- 
jeftures  plentiful,  too  much  has^pcrhaps  beuVfaid  iflresdy.     N. 

Mufchen- 


88  Smics.—.Metms  cf  Fluids, 

Mufchenbroek  and  mod  of  the  philofophers  of  the  prefent  century  have  attributed 
fcarcely  any  other  fun£lion  to  the  air  than  that  of  comprefTing  the  caloric  or  fuel  in  « 
flate  of  combuftion,  and  blowing  away  the  afhes.  Chemiftry  has  lately  proved  what 
Vinci  had  before  diicerned,  and  Mayow  and  Hooke  had  fufpecled  towards  the  end  of  the 
laft  century. 

VII.  and  Vlir.  On  Statics. — The  author  explains  the  theory  of  the  oblique  lever,  the 
inclined  plane,  and  the  general  principle  of  virtual  velocities  in  machines. 

Vinci  and  Galileo  both  obferved,  that  the  defcent  of  heavy  bodies  is  made  more  fpeedily 
through  an  arc  of  a  circle  than  by  an  inclined  plane  ;  but  their  proofs  are  imperfect  in  cer- 
tain rcfpe£ls.  It  has  fince  been  dcmonftrated  that  the  cycloid  is  the  curve  of  quickeft  de- 
fcent. Neverthelefs,  I  find  that  there  is  a  minimum  of  time  of  defcent  in  a  circular  arc, 
which  may  be  determined  in  a  fynthetical  method  of  confiderable  fimplicity,  by  means  of 
the  following  theorem. 

An  arc  of  a  circle  which  does  not.  exceed  60°  is  a  curve  of  fpeedier  defcent  than  any 
other  curve  which  can  be  drawn  within  the  fame  arc  : — and  the  arc  of  90°  is  a  curve  of 
fpeedier  defcent  than  any  other  curve  which  can  be  drawn  without  the  fame  arc*. 

IX.  Concerning  water  drawn  from  a  canal. — The  quantity  of  water  which  iflues  from  a 
canal  through  a  given  aperture,  may  vary  from  many  caufes.  i.  From  the  greater  or  lefs 
height  of  the  water  of  the  canal  above  the  aperture.  2.  From  the  greater  or  lefs  fwiftnefs 
of  the  water  along  the  fide  or  bank,  in  which  the  opening  is  made.  3.  From  the  greater 
or  lefs  convergence  of  the  fides  of  the  aperture.  4.  The  greater  or  lefs  thicknefs  of  the 
fide  of  the  canal.  5.  Whether  the  aperture  be  circular,  fquare,  triangular,  or  oblong. 
6.  Bccaufe  the  aperture  is  more  or  lefs  obliquely  fituated  with  regard  to  the  bearing  or 
dire£lion  of  the  fide.  7.  Or  more  or  lefs  Inclined  to  the  horizon.  8.  Whether  the  opening 
be  in  a  convex  or  concave  part  of  the  bank.  9.  Whether  there  be  cavities  or  prominences 
in  the  bed  of  the  canal  oppofite  the  aperture.  10.  Whether  the  air  do  or  do  not  infinuate 
jtfelf  into  the  current  of  water  which  iflues  forth.  1 1.  Whether  the  water  at  its  emiflion 
fall  freely  in  the  air,  or  is  conducted  away  by  an  open  trough,  or  by  a  pipe  clofed  all 
round.  12.  Whether  this  conducing  pipe  have  a  greater  or  lefs  diameter  with  regard  to 
the  quantity  of  water  which  defcends  in  the  tube  itfelf.  13.  Whether  the  fame  conduc- 
ing pipe  have  a  greater  or  lefs  length  in  its  defcent.  And  14.  Whether  the  bore  of  this 
pipe  be  equal  or  rough,  ftraight  or  curved. 

It  muft  be  admitted  here,  as  well  as  elfewhere,  that  De  Vinci,  though  poflefled  of  a  mind 
fo  powerful  as  to  difcern  the  true  caufes  of  natural  phenomena,  had  not  the  advantage  of 
modern  analyfis  to  afcertain  and  demonflrate  the  quantum  of  a£tion  of  thefe  caufes.  But, 
on  the  other  hand,  it  muft  be  allowed  that  hydraulics  even  in  our  time  has  not  yet  perfedly 
and  accurately  determined  all  the  laws  according  to  which  the  fourteen  circumftances 
pointed  out  by  Leonardo  afFeft  the  quantity  of  water  emitted  through  an  aperture  of  a 
given  magnitude. 

X.  Concerning  circular  eddies,  or  whirls  of  water.— The  author  marks  the  efFe<^  of  the 
inertia  of  bodies  which  produces  a  centrifugal  force  in  curve-lined  motions.  He  remarks  that 
the  cavity  produced  in  water  by  a  whirling  motion  is  leaft  at  the  bottom,  becaufe  there  the 

*  For  the  demonftration  I  muft  refer  to  the  Effay,  p.  19.    N. 

o  prcflure 


Vifton. — Military  Worhs.—Inflrununts.  8g 

ipreflure  Is  greatefl;  and  that,  contrary  to  the  obfervablc  motion  in  a  wheel,  the  part$ 
neareft  the  axis  in  the  prefent  cafe  move  the  fwifteft  *. 

XI.  On  vlfion. — ^The  invcrfion  of  images  formed  in  the  darkened  chamber  by  rays  ad- 
mitted through  a  fmali  hole  in  a  plate  of  metal  are  explained  by  a  diagram,  and  applied 
to  the  phenomena  of  vifion.  It  is  alfo  remarked,  that  the  apparent  magnitude  of  remote 
obje£ts  may  be  enlarged  by  rendering  the  pencils  of  light  more  convergent.  This  is 
iliewn  by  a  figure,  but  the  means  are  not  pcrfpicuoufly  explained. 

XII.  On  military  architeiTlure. — Under  this  title  the  author  gives  diredlions  for  con^ 
ftru£Ving  military  works  ;  and  confiders  their  relative  properties  with  regard  to  attack  and 
defence.  He  exhibits,  as  his  commentator  remarks,  a  fketch  nearly  complete  of  the  art 
of  fortification,  and,  the  attack  and  defence  of  places,  at  the  commencement  of  the  fix- 
teenth  century.  We  obferve  platforms,  buttrefies  or  counterforts,  ravelins,  the  glacis 
furrounding  the  ditch,  trenches,  advantages  of  the  ricochet,  mines  and  countermines,  and 
in  fome  defigns  of  de  Vinci  there  are  even  counterguards.  It  muft  however  be  remarked, 
that  Leonardo  was  much  fuperior  to  tlie  engineers  of  his  time  ;  in  proof  of  which  his  ob- 
fervations  in  this  feflion  may  be  compared  with  what  Machiavel  delivers  on  the  fame 
fubjedt  in  his  Art  of  War,  and  what  Albert  Durer  has  written  upon  fortification  f. 

It  is  pretended  that  the  baftions  of  Verona  %  were  the  firft  which  were  conftrufted  with 
right-lined  faces,  fianked  in  the  modern  fafliion  ;  and  the  merit  of  this  invention  has  been 
afcribed  to  San  Michel.  The  baftions  of  Verona  were  however  conftruded  after  the  death 
of  Leonardo,  who  had  explained  the  necelTity  of  that  difpofition,  and  has  marked  embrafures 
in  each  flank  of  the  baftion  in  one  of  his  figures. 

Geufs,  in  his  Theorie  de  PArt  du  Minetir  ||,  reproaches  Valliere  for  having  robbed  Peter 
Navarro  of  the  glory  of  the  invention  of  mines,  to  attribute  it  without  foundation  to 
Francis  G  eorgi  §.  Valliere  may  be  defended  by  the  tefl;imony  of  Biringuccio,  who  was  the 
countryman  and  contemporary  of  Georgi.  He  exprcfsly  fays  H,  "  that  it  was  this  en- 
gineer who,  being  confulted  by  Navarro  refpe£ting  the  means  of  taking  the  caftle  of 
Naples,  propofed  and  executed  the  mines,  and  that  the  glory  remained  with  the  com- 
mander General  Navarro,  becaufe  renown  difpofes  itfelf  on  the  fide  of  great  men."  But, 
in  faft,  the  invention  of  mines  with  gun-powder  is  more  ancient  than  either  of  thefe  per- 
fonages.  The  Genoefe  executed  them  in  1487  **.  The  manufcript  N"  7239  of  the 
French  National  Library  was  written  by  an  Italian  who  lived  at  the  commencement  of 
the  15th  century.  The  author  explains  very  clearly  (fol.  32)  the  manner  of  taking  a 
caftle  fituated  on  a  mountain,  by  the  operation  of  mines  ff. 

XIII.  Concerning  certain  inftruments. — i.  The  proportional  compafles.  Its  centre  is 
moveable  ;  and,  as  the  author  remarks,  it  may  be  ufed  for  the  proportions  of  incommen- 
furable  quantities,  and  alfo  to  form  an  oval  which  (hall  have  a  given  ratio  to  a  given 

*  ProfelTor  Vcnturi  has  treated  this  fubjeft  in  his  Recherches  Experimemales,  &c.  p.  5R,  for  an  account  of 
vvhich  work  fee  our  Journal,  I.  525. 

f  De  urbibus  arcibus  caftellis,  fol.  Paris,  1535.  %  MafFei  Iftocia  di  Verona,  part.  3,  cap.  4. 

jl  In  8vo.  Maftricht  1778.  §  21.  §  Folard,  torn.  iii. 

^  Pyrotechnia,  !iv.  ip.  cap.  4.  •»  Guieciardini  Iftoria,  lib.  vi.  i 

t+  Mr.Venturi  gives  a  more  particular  account  of  this  manufcript  and  its  contents  in  the  notices  at  the  end 
of  the  prefent  treatife. 

Vol, TL— Mat  1798.  N  circle. 


po  Greek  Firt.'—Extra^ioft  and  Purijication  of  Oil, 

•circle.  M.  Venturl  informs  us,  that  from  a  drawing  in  the  manufcrip,t  it  does  not  appeat 
to  have  been  different  from  the  inftrument  now  in  ufe.  2.  An  inftrument  to  fliew  the 
conftitution  and  denfity  of  the  air,  and  when  the  weather  inclines  to  rain.  From  the 
figure  it  appears  to  have  been  a  balance  loaded  at  each  end,  and  provided  with  a  graduated 
circle  to  fhew  its  changes  of  inclination.  M.  Venturi  thinks  that  one  of  the  weights  iri 
equilibrio  was  a  body  proper  to  become  charged  with  the  humidity  of  the  atmofpherc. 
This  does  not  very  well  agree  with  the  confideration  of  denfity,  though  it  muft  be  con- 
feffed  that  the  equal  magnitudes  of  the  two  weights  in  the  drawing  do  not  give  much 
countenance  to  the  notion  of  its  having  been  a  ftatical  barofcope.  3.  A  leathern  cafe  or 
clothing  for  a  diver  in  the  pearl  lilhcry.  4.  A  piece  (baton )  which  locks  alternately  in  the 
teeth  of  a  crown  wheel  to  operate  like  the  verge  of  the  balance  in  clocks ;  but  for  what 
purpofe  is  not  faid  *. 

XIV.  Two  chemical  procfefles. — i.  A  flaming  ball  compofed  in  the  following  manner  :— 
Take  the  charcoal  of  willow,  nitre,  brandy,  refm,  fulphur,  pitch,  and  camphor.  Mix  the 
whole  together  over  the  fire.  Plunge  a  woollen  cord  in  the  mixture,  and  form  it  into  balls, 
which  may  afterwards  be  provided  with  fpikes.  Thefe  balls  being  fet  on  fire,  are  thrown 
into  the  enemy's  vefiels.  It  is  called  the  Greek  fire,  and  is  a  fingular  compofition,  for  it 
burns  even  upon  the  water.  Callinicus  the  architeft  taught  this  compofition  to  the  Ro- 
mans (of  Conftantinople),  who  derived  great  advantage  from  it,  particularly  under  the  em- 
peror Leo,  when  the  Orientals  attacked  Conftantinople.  A  great  numbed  of  their  veflels 
were  burned  by  means  of  this  compofition. 

2.  Oil  fit  for  painting.  Choofe  the  moft  perfcv^  nuts,  take  off  the  fiiell,  foak  them  in  a 
veflel  of  water  to  feparate  the  (kin ;  then  leave  the  kernels  in  clear  water,  which  is  to  be 
changed  as  often  as  it  becomes  turbid,  which  may  be  fix  or  eight  times.  After  a  certain 
time,  the  nuts  on  being  ftirred  will  be  found  to  mix  with  the  water,  and  form  a  folution 
refembling  milk.  Expofe  this  in  plates  to  the  open  air,  and  the  oil  will  rife  to  the  furface. 
In  order  to  obtain  this  oil  very  clean  and  pure,  provide  cotton  wicks,  one  end  of  which  is 
to  be  dipped  in  the  oil,  while  the  other  part  pafles  over  the  border  of  the  veflel,  and  de-  - 
fcends  into  the  neck  of  a  glafs  phial  two  inches  below  the  furface  of  the  liquor  in  the 
plate.  The  oil  will  by  degrees  filtrate  along  the  wick,  and  pafs  very  fine  into  the  phial, 
all  the  impurities  remaining  in  the  plate.  All  the  oils  of  grain  and  of  nuts  are  equally  clear. 
It  is  the  manner  of  extradting  them  which  renders  them  foul. 

The  compofition  of  the  Greek  fire  here  given  by  Vinci,  is  found  nearly  in  the  fame 
■words  in  Baptifta  Portaf,  whence  it  appears  that  both  authors  derived  their  information 
from  the  fame  fource.  The  modern  difcoveries  in  chemiftry  refpe£ling  combuftion  have 
dlfclofed  the  whole  fecret  of  compofitions  which  burn  without  accefs  to  the  atmofphere, 
but  by  means  of  oxygene  afforded  from  nitre.  The  balls  defcribed  by  Frezler  J,  which 
fliine  on  the  furface  of  water,  are  nothing  elfe  but  the  Greek  fire. 

XV.  Concerning  method. — It  is  always  of  advantage  to  the  underftanding  to  acquire 

•  The  interefting  commentary  or  note  on  this  laft  jjaffage  has  already  been  given,   for  the  moft  part,  at 
page  51  of  tht  prefent  number, 

+  Mag.  Natur.  lib.  xii.  cap.  i. 

J  Des  feux  d'artifices, edit,  de  1747,  p.  355.    See  alfo  p.  334, 

knowledge 


Remarltahk  Chunges  of  Jj^nily  iy  Cold.  gi 

ItiiowkJge  wliatevcr  may  be  its  nature ;  we  may  afterwards  choofe  the  good,  and  reje£l  the 
ufelefs.  (Qu.?) 

Theory  is  the  General ;  Pra<5lice  is  the  Army. 

Experiment  is  the  interpreter  of  the  contrivances  of  nature.  This  interpreter  never 
deceives  us.  Our  judgment  fomeiimes  mifleads  itfclf  in  expectation  of  confequences 
which  experiment  rcfufes  to  verify.— We  mud  recur  to  experiment,  and  vary  the  circum- 
flanees  until  we  have  deduced  general  rules,  for  it  is  experience  which  afFords  the  true 
rules. — But  you  may  afk,  What  is  the  advantage  of  thefe  rules  ?  I  reply,  that  they  direct 
our  refearches  into  nature,  and  the  operations  of  art.  They  prevent  us  from  deceiving  our- 
felves  or  others  by  the  promife  of  refults  which  cannot  be  obtained. 

There  is  no  certainty  in  fciences  to  which  fome  part  of  the  mathematics  cannot  be  ap- 
plied, or  which  do  not  depend  in  fome  manner  upon  mathematical  knowledge. 

In  the  ftudy  of  fciences  which  depend  on  the  mathematics,  thofe  who  do  not  confult 
nature,  but  authors,  are  not  the  children  of  nature.  I  would  call  them  her  grand-children. 
Nature,  in  fa£t,  is  the  fole  leader  of  true  genius.  But  fuch  is  the  folly  of  men.  He  who 
choofes  rather  to  learn  from  the  original  fource,  inftead  of  applying  to  authors^  becomes 
an  obje£l  of  derlfion  for  his  fingularity  *. 

Obfevvatlons  and  Experiments  on  the  Formation  of  Sulphate  of  Soda,  or  Glauler's  Salt,  in  Salt 
WaterSy  at  a  Temperature  beneath  the  Freezing  Point  of  Water,  and  upon'  an  eafy  Method  of 
difengaging  all  the  deliquefcent  Salts.     By  M.  Gren  \. 

H  E  influence  of  temperature  upon  the  eftabliflied  laws  of  mutual  decompofition  of 
the  neutral  and  middle  falts,  is  a  circumftance  very  eflential  to  be  obferved.  Many  falts 
are  not  decompofed  above  the  temperature  of  freezing  water,  though  very  well  beneath 
that  temperature.  Such,  for  example,  are  the  fulphate  of  alumine  and  the  muriate  of 
foda;  the  fulphate  of  magnefia  and  the  fame  muriate. 

The  formation  of  Glauber's  fait  during  congelation  in  fait  water,  wherein  previous  ana- 
lyGs  did  not  difcover  it,  had  long  fince  engaged  the  attention  of  the  author.  He  concluded 
that  the  fulphate  of  foda  owed  its  origin  to  the  mutual  decompofition  of  fulphate  of  lime 
and  muriate  of  foda,  at  a  temperature  below  zero.  A  more  accurate  analyfis  of  thefe  wa- 
ters after  the  fevere  cold  of  1794  and  1795,  proved  that  he  was  miftaken,  and  that  the 
fulphate  of  foda  had  been  formed  by  the  double  decompofition  of  the  muriate  of  foda  and 
the  fulphate  of  magnefia.  The  excefllve  cold  of  1785  had  already  exhibited  this  decom- 
pofition to  Scheele,  and  he  had  (hown  that  fulphate  of  foda  was  produced  from  a  mixture 
.  of  two  parts  of  the  folution  of  fulphate  of  magnefia,  and  one  part  of  the  muriate  of  foda, 
erpofed  to  the  temperature  of  ice. 

*  Profeffor  "Venturi  intends  to  publifh  as  fpeedily  as  circumftances  will  permit,  Ip  three  complete  treatifes,  the 
whole  works  of  De  Vinci  on  mechanics,  hydraulics,  and  optics.      N.  .   .   .  ■ 

-.  f  The  memoir  of  M.  Gren  was  addreffed  by  himfelf  in  thanufcript  to  the  Council  of  Mines  in  Fraricl, 
ivhc  publiflied  it  in  the  xxviith  Number  of  the  Journal  des  Mines.  Citizen  Defcotiis  abridged  the  fame  in  the 
s^ivth  volume  of  the  Annales  de  Chimie,  pageiu.  The  above  pspsr  is  a  tranfiation  frpm  his.  abridgment.  N. 

N2  M.  Grca 


92  Eafy  Methods  of  rendering  eemmen  Salt  very  pure. 

M.  Gren  was  convinced  by  experiment,  that  the  fulphate  of  niagnefia  in  fait  waters  form* 
at  a  fufficient  degree  of  cold  all  the  fulphate  of  foda  which  can  then  be  afforded,  and  of 
which  they  did  not  before  contain  the  fmalleft  particle.  He  endeavoured,  but  conftantly 
without  fuccefs,  to  reproduce  the  muriate  of  foda,  and  the  fulphate  of  magnefia,  by  an  ele- 
vation of  temperature.  So  that  fait  waters  which  contain  fulphate  of  magnefia  change 
their  nature ;  and  their  compofition  is  no  longer  the  fame  when  they  have  been  fubje6ted 
to  feme  degrees  of  cold  below  the  freezing  point  5  and  a  fubfequent  increafe  of  heat  will 
not  reftore  their  former  ftate. 

The  quantity  of  muriate  of  magnefia  in  fait  waters  which  contain  fulphate  of  magnefia, 
is  increafed  by  a  temperature  beneath  zero.  It  is  therefore  produ£live  of  a  real  lofs  to 
fuffer  the  fait  water  to  remain  m  the  bafons  during  the  winter,  becaufe  they  will  after- 
wards afford  a  muriate  of  foda  of  a  bad  quality,  and  the  fulphate  of  foda  which  is  ob- 
tained will  not  compenfate  for  this  difadvantage.  It  appears  likevvife  that  the  hope  of  con- 
centrating fea  water  by  frofl  is  chimerical. 

It  was  an  important  queflion  to  be  rcfolved  in  the  art  of  making  fait,  what  might  be  the 
means  of  feparating  the  deliquefcent  falts  even  before  the  evaporation.  la  this  refpedl 
M.  Gren  has  fucceeded.  His  procefles  are  founded  on  the  decompofition,  well  known  to 
chemifts,  of  muriate  of  lime  by  fulphate  of  foda,  «nd  muriate  of  magnefia  by  cauflic  lime. 

If  the  water  contain  only  muriate  of  lime  with  the  muriate  of  foda,  the  fulphate  of  foda 
is  fufficient :  if  there  remain  muriate  of  magnefia  and  fulphate  of  foda,  lime  will  fuffice. 
In  this  cafe  muriate  of  lime  is  formed,  which  afterwards  decompofes  the  fulphate  of  fod* 
by  double  affinity. 

If  the  water  contain  the  muriate  and  fulphate  of  magnefia  without  fulphate  of  foda,  It 
will  be  neceffary  to  employ  lime  and  fulphate  of  foda  at  the  fame  time. 

The  fame  fubftances  muft  alfo  be  employed,  if  the  water  contain  the  muriates  of  lime 
and  magnefia  together;  which  then  entirely  exclude  the  fulphates  of  foda  and  of  magnefia. 

Laftly,  if  the  fulphate  and  the  muriate  of  magnefia  be  prefent  with  the  fulphate  of  foda, 
lime  only  need  be  employed,  unlefs  the  quantity  of  the  fulphate  of  foda  be  found  infuf- 
ficient.     In  this  cafe  a  portion  of  the  fait  muft  be  added. 

Thefe  procelTes  introduce  no  foreign  fait  into  the  waters,  becaufe  they  are  already  fatu- 
rated  with  fulphate  of  lime,  which  docs  not  render  the  muriate  of  foda  more  impure,  be- 
caufe it  feparates  in  the  ftate  of  fchlot.  They  have  the  advantage  to  clear  it  of  the  ful- 
phates of  foda  and  magnefia,  which  alter  the  purity  of  the  muriate  of  foda,  and  render  it 
bitter.  Befides  which,  in  the  practice,  no  mother  water  remains.  The  whole  of  the  fluid 
may  be  evaporated  to  the  laft  drop,  and  all  the  fait  extra£led,  which  will  conftantly  be 
pure  marine  fait.  The  diredtors  of  fait  works  will  eafily  perceive  how  much  profit  will 
thus  be  obtained  with  regard  to  time  and  fuel  confumed  in  the  evaporation  and  drying  of 
the  falts.  But  this  is  merely  a  fecondary  profit,  greatly  inferior  to  the  principal  advantage 
of  obtaining  a  pure  fait  not  deliquefcent,  but  capable  of  refifting  the  impreffion  of  the  air, 
and  of  being  preferved  and  tranfported  without  lofs. 

The  ftrongeft  objedion  againft  the  ufe  of  thefe  procefTes  may  arife  from  the  neceflity  of 
purchafing  fulphate  of  foda  ;  and  this  obje(flion  would  be  very  well  founded,  if  the  fait  wa- 
ters were  not  for  the  moft  part  of  fuch  a  nature  as  to  afford  it  themfelves  at  a  fmall  ex- 
pcncc;  that  is  to  fay,  by  their  maceration  at  a  temperature  below  zero.  It  would  be  fuffi- 
cient 


New  Bark /or  Dyeing,  called  Paraguatan.  93 

eient  to  leave  a  certain  quantity  in  the  bafons  expofed  to  the  cold  during  the  winter.  It 
would  not  indeed  be  proper  to  extraft  the  common  fait  from  thefe  waters,  after  having 
feparated  the  fulphate  of  foda,  becaufe  they  would  then  contain  too  great  a  quantity  of  mu- 
riate of  magnefia.  It  would  be  more  advantageous  to  add  fulphate  of  iron  to  prepare  the 
fulphates  of  foda  and  of  magnefia. 

With  regard  to  fuch  waters  as  do  not  contain  any  fulphate  of  magnefia,  which  is  very 
rare,  it  would  (till  be  of  advantage  to  purify  them  by  thefe  means ;  becaufe  the  water  mull 
be  very  bad,  and  highly  charged  with  deliquefcent  falts,  to  require  more  than  fifty  or  fe- 
venty-five  pounds  of  fulphate  of  foda  for  thirty  quintals  of  fait  obtained  by  evaporation. 

In  order  to  make  ufe  of  this  method,  it  is  proper  to  be  well  acquainted  with  the  prin- 
ciples which  enter  into  the  compofition  of  the  water  intended  to  be  purified.  It  then  will 
be  known  whether  lime  alone,  or  fulphate  of  foda,  or  both  fubllances  together,  ought  to  be 
ufed.  Immediate  experiment  muft  afterwards  determine  what  quantity  ought  to  be  ufcd 
to  infure  the  mod  perfeft  fuccefs. 


A  Report  made  to  the  Council  of  Trade  and  Mines  in  Spain,  on  a  new  Kind  of  Wood  for  Dyeing, 
named  Paraguatan.    By  D.  DOMINI^E  Garcia  PERNANDEZy  InfpeElor  of  Coinage  *. 


I 


N  compliance  with  the  order  of  the  Supreme  Council  of  Commerce  and  Mines  I  have 
undertaken  a  chemical  examination  of  the  wood  known  at  Guiana  by  the  name  of  Para- 
guatan j  which  I  have  carried  as  far  as  appeared  neceflary  to  afcertain  the  nature  of  the 
wood,  and  the  advantages  to  be  derived  from  it.  In  the  firfl  place  I  obferved  that  the 
bark,  the  wood  properly  fo  called,  and  the  leaves  of  paraguatan  afford  different  colourSr 
The  leaves  do  not  deferve  notice,  becaufe  they  produce  only  a  falfe  and  difagreeable  co- 
lour. My  refearches  were  chieHy  diredled  to  the  bark,  which  is  the  part  mod  deferving 
of  attention.  But  my  remarks  upon  the  bark  may  alfo  be  extended  to  the  wood  ;  for, 
though  this  affords  a  different  colour,  it  prefents  nearly  the  fame  phenomena  as  the  bark 
itfelf. 

When  the  bark  is  boiled  in  water  it  affords  a  coloured  extraft,  which,  when  expofed  to 
the  a£tion  of  the  fulphuric,  muriatic  or  nitric  acid,  refills  their  agency  for  a  longer  time 
than  brazil  or  logwood  does.  The  colour  may  be  revived  by  means  of  alkalis,  after  it  has 
been  deftroyed  by  combination  with  acids. 

Vinegar,  lemon  juice  and  tartar  render  this  colour  more  brilliant.  They  give  rt  a  fine 
rofe  colour  ;  whereas  thefe  acids  entirely  deflroy  the  colours  of  brazil  and  logwood. 

The  fecula  of  the  bark  of  paraguatan  fixes  and  attaches  itfelf  to  wool,  cotton,  and  filk. 
The  colour  is  brighter  on  filk  than  on  wool,  and  brighter  on  wool  than  on  cotton. 

The  fame  fecula  dried  is  afterwards  foluble  in  alcohol.  It  communicates  to  it  a  tinge 
fimilar  to  that  afforded  by  cochenille.  : 

By  mixing  alum  with  a  very  concentrated  decoftion  of  the  fame  fubftance,  a  kind  6£ 

*  Tranflated  from  the  Spanifh  by  Cit.  Venturi,  Annales  dc  Chimie,  XXlH.  3«o. 

lac 


94  New  Dyeing  Bark,  Paraguafait. 

lac  is  obtained,  which  Is  neither  fo  bright  nor  fo  beautiful  as  is  obtained  from  cochcnllie 
■by  the  fame  procefs. 

The  fame  deco£lion  mixed  with  nut  galls  afforded  me  a  precipitate  of  a  faint  rpfe  co- 
lour. The  infufions  of  brazil  wood  and  logwood  mixed  with  the  Infufion  of  galls  affunie 
a  deeper  and  browner  colour.  Ours,  on  the  contrary,  becomes  brighter,  and  aflumes  a 
pale  tinge  of  the  rofe,  or  fome  other  finiilar  and  delicate  colour. 

It  mud  be  confefled  that  the  colour  obtained  from  paraguatan  has  not  the  force  of  that 
of  cochenille.  But  it  is  fupcrior  to  thofe  of  madder,  brazil  wood,  and  logwood.  For  it 
refills  vinegar,  lemon  juice,  and  tartar.  Soap  itfelf  does  not  deftroy  it  fo  quickly  as  it  does 
thofe  of  brazil  and  logwood. 

Our  bark  likewife  affords  the  advantage,  that,  by  employing  it  in  certain  dofes,  and 
giving  a  due  preparation  to  filk,  we  may  obtain  various  fhades  of  rofc  and  poppy  colour, 
which  cannot  be  had  by  means  of  carthamus  but  by  difficult  proceffes,  long  wafhings,  al- 
kaline mixtures,  and  other  embarraffing  manipulations. 

By  examination  of  the  external  appearance  of  a  piece  of  the  wood  of  paraguatan, 
it  appears  to  me  to  be  the  fame  tree  which  Francis  Correal  *  fays  he  obferved  in 
the  province  of  Popayan,  not  far  from  Guiana.  The  fame  author  relates,  that  this  tree 
is  different  from  that  of  brazil  •,  that  the  trunk  is  of  the  thickness  of  a  man's  thigh ; 
that  its  bark  is  filled  with  longitudinal  indentations ;  that  the  wood  and  bark  are  of 
a  fins  red  ;  and  that  the  Indians  ufe  this  wood  inlxed  with  a  red  earth  to  dye  their 
cotton  garments. 

The  colour  obtained  from  paraguatan  does  not  refill  the  a£lIon  of  light.  No  colour  can 
withftand  this  tefl.  It  is  enough  that  our  colour  withftands  it  longer  than  thofe  of  brazil 
and  logwood.  I  muff  not  conceal,  that  thefe  two  trees  afford  the  colouring  matter  in  greater 
abundance  than  the  paraguatan. 

From  thefe  fa6ls  I  confider  the  paraguatan  as  one  of  the  mofl  valuable  produdllons 
which  America  furniflies  to  Spain.  It  may  be  advantageoufly  employed  in  the  art 
of  dyeing  throughout  Europe.  It  is  to  be  wilhed  that  enquiry  might  be  made  at  Po- 
payan, in  order  that  the  earth  i&id  the  wood  mentioned  by  Correal  might  be  procured. 
It  is  alfo  defirable  that  the  governor  of  Guiana  fhould  colleft  all  the  information  which 
■can  be  procured  refpeding  the  paraguatan,  and  tranfmit  the  fame  to  us  with  other  famples 
of  the  wood,  the  leaves  and  the  flowers  of  this  tree,  to  enable  us  to  determine  its  fpecies. 

The  knowledge  of  this  wood  begins  to  be  extended.  For  I  have  lately  received  a  portion 
of  its  bark,  and  a  red  matter  which  an  Englifhman,  named  Milnes,  has  obtained  from 
Guiana.  It  is  to  be  prefumed  that  this  matter  is  the  fame  as  is  mentioned  by  Francis 
Correal  in  his  travels. 


SCIENTIFIC    NEWS. 

J.  HE  admlniflratlon  of  finances  and  contributions  of  the  French  Republic  In  Italy,  hav- 
ing at  its  difpofal  a  great  number  of  the  moft  valuable  pieces  of  fculpture,  painting,  and 
marblesf,  arifing  from  confifcations  made  of  (the  property  of)  the  enemies  of  the  French 

*  Voyage  aux  Indes  Occidcntales,  p.  4zo,  of  the  French  tranflation  printed  in  1722. 
fMarires,  which  I  underftand-Ui  denote  tablets,  ftatues,  bas-reliifs,  and  every  other  woik  formed  of  inarble.  N. 

Republic, 


Sale  of  Paintings,  fs'f.  in  Italy.— Civil  Engineers,  9  <f 

Republic,  being  defirous  of  fpeedily  difpofing  of  all  thefe  mafter-picces  of  art,  has  charged 
citizen  Hubert  (who  is)  attached  to  the  adminiftration  of  finances  in  quality  of  artift,  to 
offer  them  forfale  to  individuals,  or  focieties.  The  lovers  of  the  arts,  academies  of  paint- 
ing, fculpture,  and  the  fciences,  will  have  a  matchlefs  opportunity  of  acquiring  the  trea- 
fures  of  art,  of  which  catalogues  are  in  the  hands  of  the  whole  world,  and  defcriptions  in 
all  the  publications  of  travels  through  Italy. 

It  will  therefore  fuffice  to  offer  for  fale  the  marbles  of  the  famous  Villa  Albani,  the  gal- 
leries of  the  Princes  Albani,  Brafchi,  and  other  monuments,  of  which  a  catalogue  will  be 
given,  with  eftimates  of  price  made  by  artifts,  upon  which  a  confiderable  abatement  will  be 
allowed.  Bills  (payable)  in  gold  or  filver  on  neutral  countries,  fuch  as  Florence,  Venice, 
Vienna,  and  even  Switzerland,  will  be  accepted.  Purchafers  belonging  to  nations  at  war 
with  France  will  have  paffports  for  tranfporting  whatever  they  may  purchafe,  whether  by 
land  or  by  fea,  and  for  embarking  the  fame  at  the  ports  of  Rome  and  Civita  Vecchia.  The 
agents  belonging  to  the  fame  inimical  powers  may,  on  their  approach  to  Italy,  procure  all 
the  neceffary  paffports  to  come  with  all  fecurity  to  treat  and  choofe  themfelves  the  objects 
which  may  fuit  their  wilhes,  by  addreffmg  Citizen  Hubert,  rue  de  la  Croce,  at  Rome. 
Speed  and  ready  money  are  the  beft  means  to  be  ufed  in  this  bufinefs.     Feb.  28th,  1798. 

The  foregoing  advertifement  was  fent  by  the  therein  mentioned  Hubert  to  Mr.  Trevor, 
the  Britifli  Miniller  at  Turin,  and  by  him  tranfmitted  to  Sir  Richard  Worflcy  in  London, 
■where  it  arrived  on  the  '27th  of  March.  1  obtained  it  of  the  Right  Hon.  Sir  Jofeph  Banks, 
Bart.  It  is  unneceffary  for  me  to  make  any  comment,  either  political  or  otherwife,  on  Its 
contents.  wmm 

Account  of  the  Society  of  Civil  Engineers.    [Concluded  from  p.  48.] 

THE  fame  period  gave  rife  alfo  to  an  affociation  of  fome  gentlemen  employed  as  above- 
mentioned.  They  often  met  accidentally,  prior  to  that  union,  in  the  houfes  of  parliament 
and  in  courts  of  juflice,  each  maintaining  the  propriety  of  his  own  defigns,  without  know- 
ing much  of  each  other.  It  was  however  propofed  by  one  gentleman  to  Mr.  Smeaton, 
that  fuch  a  ftate  of  the  profeffion,  then  crude  and  in  its  infancy,  was  improper  ;  and  that  it 
would  be  well  if  fome  fort  of  occafional  meeting  in  a  friendly  way  was  to  be  held,  where 
they  might  fliake  hands  together  and  be  perfonally  known  to  one  another.  That  thus  the 
fharp  edges  of  their  minds  might  be  rubbed  off,  as  it  were,  by  a  clofer  communication  of 
ideas,  no  ways  naturally  hodile;  and  might  promote  the  true  end  of  the  public  bufinefs  upon- 
which  they  fliould  happen  to  meet  in  the  courfe  of  their  employment,  without  joftling  one 
another  with  rudenefs  too  common  in  the  unworthy  part  of  the  advocates  of  the  law,  whofe  ' 
jntereft  it  might  be  to  pufli  them  on  perhaps  too  far  in  difcuJIing  points  in  contefl. 

Mr.  Smeaton  immediately  perceived  the  utility  of  the  idea,  and  at  once  embraced  it.  In' 
March  1771,  a  fmall  meeting  was  firft  eftablifhed  on  Friday  evenings,  after  the  labours  of' 
the  day  were  over,  at  the  Queen's  Head  tavern,  Holborn.  And  from  a  few  members  at 
firft,  it  foon  increafed,  fo  that  in  the  fpace  of  twenty  years  they  amounted  to  fixty-five  and 
upwards.  But  of  thefe  there  were  only  about  fifteen  who  were  real  engineers  employed 
in  public  works,  or  private  undertakings  of  great  magnitude. 

Among  thefe  we  find  the  names  of  Yeoman,  Smeaton,  Grundy,  Milne,  Nickallsj  Jeffop,''^ 
Golborne,  Whitworth,  Edwards,  Jofeph  Prieftlcy,  Major  Watfon,  Bouhon,  Whltfehurft, 
Rennie,  Watt,  and  fome  others.     The  other  members  were  either  amateurs,  or  ingenidtHfl 
workmen  and  artificers  conneded  with  and  employed  in  works  of  engineering.  'liii}?!" 

This 


p6  Sod  ft y  of  Civil  Engineers, 

This  afibciation  declared  itfelf  a  fociety,  and  a  regifter  was  kept  of  the  names  and  nam* 
bers  of  its  members.  Converfation,  argument,  and  a  focial  communication  of  ideas  and 
knowledge  in  the  particular  walks  of  each  member,  were  at  the  fame  time  the  amufement 
and  the  bufmcfs  of  the  meetings. 

In  this  manner,  fometimes  well  attended,  and  at  other  times  not  fo,  as  the  members  were 
dlfpcrfed  all  over  England,  the  fociety  proceeded  until  May  1792,  when  it  ceafed  to  exifl: 
by  mutual  confent  of  the  principal  members. 

home  untoward  circumftances  in  the  behaviour  of  one  gentleman  towards  Mr.  Smeaton, 
gave  rife  to  the  difunion.  No  one  was  ever  more  obliged  than  that  gentleman  (who  is  now 
cleceafed)  to  Air.  Smeaton  for  promoting  him  in  bufniefs,  and  many  effential  offices  in  life. 
The  offence  given  was  done  away  by  an  apology  at  the  defire  of  the  company,  and  by  the 
good-nature  of  Mr.  Smeaton  j  but  the  remembrance  of  it  had  an  efFe£t  on  all  prefent. 

Afterwards  it  was  conceived  and  intended  to  renew  this  fociety  in  a  better  and  more 
refpeciable  form.  Steps  were  taken  for  that  purpofe,  and  Mr.  Smeaton  agreed  to  be  a 
member.  But  before  the  firft  meeting  could  be  held,  he  was  no  more.  He  died  the 
2iith  of  October  1792,  and  their  firlt  meeting  was  in  April  1793. 

It  was  conceived  it  would  be  a  better  plan  that  the  members  fliould  dine  together  at  a 
late  hour  after  attendance  in  parliament,  and  pafs  the  evening  in  that  fpecics  of  conver- 
fation which  provokes  the  communication  of  knowledge  more  readily  and  rapidly  than  it 
can  be  obtained  from  private  lludy  or  books  alone. 

The  firll  meeting  of  this  new  inllitution.  The  Society  of  Civil  Engineers,  was  held  on  the 
15th  of  April  1793,  by  Mr.  Jeflbp,  Mr.  Mylne,  Mr.  Rennie,  and  Mr.  Whitworth. 

The  conftitutioH  was  agreed  on,  and  afterwards  acceded  to  by  all.  That  there  fliould 
be  three  claffes  in  the  fociety.  The  firft  clafs  as  ordinary  members,  to  confift  of  real  en- 
gineers, adually  employed  as  fuch  in  public  or  in  private  fervicc.  The  fecond  clafs  as 
honorary  members,  to  confift  of  men  of  fcience,  and  gentlemen  of  rank  and  fortune,  who 
had  applied  their  minds  to  fubje£ts  of  civil  engineering,  and  who  might,  for  talents  and 
knowledge,  have  been  real  engineers,  if  it  had  been  their  good  fortune  to  have  it  in  their 
power  to  employ  others  in  this  profeffion  :  and  alfo  of  thofe  who  are  employed  in  other 
public  fervice,  where  fuch  and  fimilar  kinds  of  knowledge  are  neceflary.  And  the  third  clafs 
as  honorary  members  alfo,  to  confift  of  various  artifts,  whofe  profeflions  and  employments 
are  neceffary  and  ufeful  to,  as  well  as  connedted  with,  civil  engineering. 

The  meetings  are  held  at  the  Crown  and  Anchor  in  the  Strand,  every  other  Friday 
during  the  feflion  of  parliament.     And  the  lift  of  members  are:   Of  the 

Firft  clafs.  Ordinary  members.  Vv'illiam  Jeflbp,  Robert  Whitworth,  John  Rennie, 
F.R.S.  Ed.  Robert  Mylne,  F.R.S.  James  Watt,  F.R.S.— L.  and  Ed.  James  Golborne,  Sir 
Thomas  H.  Page,  Knt.  F.R.S.  John  Duncombe,  Captain  Jofeph  Huddart,  F.R.S.  Henry 
Eaftburne,  William  Chapman,  MR. I. A.   James  Cockftiutt. 

Second  clafs.  The  Right  Hon.  Sir  Jofeph  Bank*,  Bart.  P.RS.  Knight  of  the  Order  of 
the  Bath,  &c.  Sir  George  A.  Shuckburgh  Evelyn,  Bart.  F.R.S.  General  Bentham,  Jofeph 
Prieftley,  Efq.  Doftor  Charles  Hutton,  F.R.S.  Henry  Oxendon,  Efq.  The  Right  Hon.  the 
Earl  of  Morton,  F.R.S.  John  Lloydd,  Efq.  F.R.S.  Rt.  Hon.  Ch.  Grevilie,  Efq.  F.R.S. 

Third  clafs.  William  Faden,  geographer;  Jefle  Ramfden,  F.R.S.  inftrument-maker,  &c. 
John  Troughton,  inftrument-maker,  &c.  John  Foulds,  mill-wright,  &c.  Samuel  Phillips, 
engine-maker  i  Samuel  Brooke,  printer  -,  John  Watte,  land-furveyor,  Sec. 


Pliiht  Journal. Fial.U.fl.lU/iuinif I). ff6. 


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JOURNAL 


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NATURAL   PHILOSOPHY,   CHEMISTRY, 


AND 


THE    ARTS. 


yuNE   1798. 


ARTICLE    L 

AhJiraBofa  Memoir  on  Camphor  and  the  Camphoric  Acid,  read  to  the  Firji  Clafs  of  the  National 
hiflitute  of  France,   By  BOUILLON  La  Grange  *. 

V>iAMPHOR,  of  which  the  relation,  the  co-exiftence,  and  almoft  the  identity  with  the 
volatile  oils,  have  long  fince  fixed  the  attention  of  chemifts,  has  appeared  to  me  to  defervc 
a  particular  examination.  I  was  defirous  of  confirming  the  difcovery  of  Mr.  Kofegarten 
on  the  property  of  camphor  to  become  converted  into  a  peculiar  acid  by  the  aftion  of  ni- 
trous acid.  The  enquiries  to  which  this  undertaking  has  led  me,  have  not  only  confirmed 
his  difcovery,  but  have  likewife  prefented  various  fa£ts  of  immediate  intereft  to  the  vege- 
table analyfis. 

-  Camphor  has  long  been  an  obje£t  of  chemical  attention.  Several  chemifl:s  have  fup- 
pofed  that  it  exifts  in  all  the  aromatic  plants,  particularly  thofe  which  contain  abundance 
of  volatile  oil ;  biit  as  the  camphor  obtained  from  mod  of  thefe  plants  conftantly  retains 
the  odour  of  the  plant  which  afforded  it,  there  is  feafon  to  think,  according  to  the  remark 
of  Citizen  Fourcroy,  that  it  is  combined  with  the  volatile  oils  of  thefe  vegetables.  I  hope 
to  clear  up  this  fadt  as  foon  &s  I  fhall  procure  a  fufficient  quantity  of  recent  volatile  oils  ; 
for  my  experiments  have  fhewn  that  thefe  afford  the  grcateft  quantity. 

Prouft,^who  has  made  experiments  relative  to  this  objeft,  has  merely  indicated  a  procefs 


♦  Annales  de  Chimie  xxiif.  '1^3. 
Vot.  II.— June  1798.  O  for 


^8  On  Camphor  and  tig  Camphoric  Acid, 

for  obtaining  the  camphor  of  feveral  volatile  oils ;  but  he  has  neither  defcribed  Its  chaw 
rafter,  nor  fliewn  in  what  refpeft  it  might  differ  from  ordinary  camphor. 

The  experiments  we  are  about  to  defcribe  may  perhaps  hereafter  afford  fome  light  on 
the  nature  of  this  fingular  fubftance. 

We  know  that  the  earths,  the  faline  earthy  fubftances,  and  the  alkalis,  have  no  aflioii 
upon  camphor ;  but  as  chemifts  had  hitherto  employed  the  alkalis  in  combination  with 
carbonic  acid,  it  was  effentially  neceffary  to  try  the  a£lion  of  the  pure  alkalis. 

1  {hall  not  here  enlarge  upon  the  various  experiments  I  have  made.  It  will  be  fufE- 
cient  to  remark,  that  I  have  obtained  no  fatisfadtory  refult.  The  camphor  is  always  vola- 
tilized. It  feems  as  if  a  fmall  quantity  was  diffolved  ;  but  it  is  fenfible  only  to  the  fmell, 
for  I  have  not  been  able  to  afcertain  its  prefence  by  any  other  means. 

The  acids  diffolve  camphor.  The  nitric  acid  is  mofl:  commonly  employed  for  this  pur- 
pofe,  to  form  a  medical  preparation  known  by  the  improper  name  of  oil  of  camphor. 

I  (hall  not  attempt  to  explain  the  inconveniencies  and  injudicious  method  of  preparing 
this  oil.  It  is  known  that  it  is  impoffibJe  to  ufe  it  in  any  vehicle  whatever  without  rege- 
nerating the  camphor  ;  confequently  there  remained  to  medical  praftitioners  no  other 
means  but  of  employing  this  oil  alone,  or  the  camphor  united  to  alcoho!.  But  if  we  exa- 
mine the  aflion  of  this  oil  on  the  animal  economy,  it  will  be  immediately  feen  that  it  can- 
not be  exhibited  alone. 

Thefe  confiderations  engaged  me  in  the  fearch  for  the  means  of  obtaining  camphor  in 
the  fluid  ftate,  without  the  addition  of  an  acid.  Though  the  refult  of  my  experiments 
has  not  been  fuccefsful,  it  will  neverthelefs  be  ufeful  to  fcience  in  fixing  our  notions  re- 
fpeding  the  nature  of  this  fubftance. 

SECTION    11. 

Procejfesfor  obtaining  the  Decompofiiicn  of  Camphor. 

TAKE  09C  part  of  camphor  and  fix  of  clay.  Let  the. clay  be  pulverized  In  the  dry  ftate, 
ijnd  fifted  through  a  fine  fieve  ;  on  the  other  hand,  the  camphor  is  to  be  pulverized  by 
means  of  alcohol,  and  the  whole  is  then  to  be  mixed  together  in  a  mortar.  When  the  mix- 
ture is  well  made,  add  a  fmall  quantity  of  water,  not  too  much,  but  enough  to  admit  of 
forming  the  matter  into  a  pafte,  which  is  to  be  made  into  balls  of  the  fize  of  an  olive. 
Place  thefe  on  a  hair  fieve  to  dry  in  a  ftove. 

When  the  balls  are  perfeftly  dry,  let  them  be  Introduced  into  a  retort,  which  is  to  be 
placed  Qti;  »  ,fand  bath,  with  a  receiver  containing  fome  diftilled  water,  and  well 
luted  at  the  neck.  In  this  difpofition  of  the  apparatus  the  retort  muft  be  gradually  heated, 
and  kept  for  feveral  hours  ip  this  ftate,  after  which  the  heat  is  to  be  raifed. 

If  the  heat  be  not  well  managed,  it  fometimes  happens  that  part  of  the  camphor  fub- 
limes  to  the  rieck  of  the  retort.  This  however  is  no  reafonfor  difcontinuing  the  procefs, 
which  muft  be  carried  on  fo  long  as  any  oil  is  feen  to  come  over.  The  fire  is  then  to  be 
put  out }  and  when  the  appawtus  is  cold,  the  receiver  may  be  unluted,  and  the  fublinied 
camphor,  as  well  as  the  refidue'In  the  retort,  muft  hie  taken  out.  The  whole  is'  th^n  'to 
be  pounded  In  a  mortar,  and  the  operation  recommenced  as  before,  until,  even  by  a  con- 
fidprable  degree  of  heat,  neither  fublimation  oor  oil  appears. 

AJecond 


Oh  CamplMf  and  the  Camphoric  Add,  v  99 

Afeeond  Procefs. 

Tlie  foregoing  operation  may  be  condufted  in  another  manner,  namely  by  reducing  the 
two  fubftances  into  a  very  fine  powder,  and  introducing  them  ipto  the  retort. 

This  method,  though  apparently  more  fpeedy,  is  in  faft  much  lefs  fo  than  the  forego- 
ing ;  for  the  camphor  rifes  with  much  more  facility,  and  the  diftillation  mud  be  oftener 
repeated,  which  renders  the  operation  much  more  tedious. 

Third  Procefs. 

Alumine  is  likewife  a  medium  which  may  be  ufed  with  advantage. 

The  alumine  is  prepared  by  means  of  ammoniac  ;  and  it  is  afterwards  waflied  with  dif- 
tilled  water,  in  order  to  obtain  it  as  pure  as  poflible.     It  is  then  (lightly  dried. 

Take  two  parts  of  alumine,  or  three,  when  it  is  wetted,  to  one  part  of  camphor.  The 
camphor  is  firft  to  be  pulverized,  and  the  alumine  afterwards  added.  The  whole  may  be 
formed  into  a  pafte  with  water,  or  otherwife  the  pulverulent  mixture  is  to  be  introduced 
into  the  retort ;  but  I  prefer  the  firft  method,  as  I  have  already  remarked.  A  receiver 
containing  fome  diftilled  water  is  then  to  be  adjufted.  The  pneumatic  apparatus  may  alfo 
be  adapted.     Diftillation  is  then  to  be  made  by  a  gentle  heat. 

By  either  of  thefe  procefles  a  volatile  oil  of  a  golden  yellow  colour  comes  over  into  the 
receiver,  and  floats  at  the  furface  of  the  water.  We  ftiall  proceed  to  defcribe  its  cha- 
rafters. 

The  diftilled  water  placed  in  the  receiver  is  not  only  neceflary  to  prevent  the  lofs  of 
oil,  which  would  attach  itfelf  to  the  interior  furface,  but  likewife  to  abforb  a  fmall  portion 
of  camphoric  acid  which  is  formed  during  the  operation.  In  faft  this  water  is  very  aro- 
matic and  penetrating  :  it  reddens  the  tinfture  of  turnfol,  and  effervefces  with  the  alka- 
line carbonates.  The  acid  itfelf,  at  the  end  of  a  certain  time,  cryftallizes  on  the  fides  of 
the  veflel. 

After  the  operation  is  completed,  the  matter  remaining  in  the  retort  is  of  a  very  deep 
black  colour. 

Four  ounces  of  camphor,  or  122,284  grammes,  may  produce 
Volatile  oil  12  gros,  or  45,856  grammes; 
Carbone  8  gros,  or  30,571  grammes; 
Carbonated  hydrogen  gas ;  carbonic  acid  ;  camphoric  acid,  each  in  proportions  which  I 
have  not  been  able  to  determine,  on  account  of  the  volatility  of  the  camphor. 

SECTION    III. 

An  Examination  of  the  Oil  obtained  from  Camphor  in  the  foregoing  Experiments. 

THE  oils  obtained  by  the  different  procefles  have  no  difference  in  their  qualities. 

This  oil  has  an  acrid  burning  tafte,  and  leaves  a  perception  of  coolnefs  on  the  tongue. 
Its  fmell  is  aromatic,  refembling  that  of  thyme  or  rofemary.  Its  colour  golden  yellow. 
When  expofed  to  the  open  air  it  partly  evaporates,  and  there  remains  a  brown  thick  yel- 
low matter  of  a  very  fharp  tafte,  but  fomewhat  more  bitter,  which  at  length  entirely  eva- 
porates. 

O  2  With 


J  00  On  Camphor  and  the  Camphoric  JdJ, 

With  the  cauft'ic  alkalis  it  affords  an  homogenous  mixture,  foluble  in  water,  and  which 
has  all  the  charafters  of  foaps  made  with  volatile  oils. 

Alcohol  diflolves  it  entirely ;  and  if  diftilled  water  be  added  to  the  folution,  the  mi?tur» 
becomes  milky,  but  affords  no  precipitate. 

When  brought  into  eontaft  with  the  oxigenated  muriatic  acid,  this  oil  becomes  very 
white,  but  no  precipitate  appears. 

It  therefore  differs  from  that  obtained  by  the  nitric  acid  ,  becaufe,  when  mixed  with 
water,  with  alkalis,  or  with  the  oxigenated  muriatic  acid,  camphor  is  regenerated. 

If  the  muriatic  acid  gas  be  pafled  through  the  oil  of  camphor  prepared  by  the  nitric  acid, 
its  colour  immediately  becomes  of  a  rofe  red,  and  the  inftant  afterwards  yellow.  This 
tail  colour  does  not  vary  until  towards  the  end  of  the  operation. 

The.  oil  itfclf  does  not  acquire  new  properties, 

S  E  C  T  I  O  N    IV. 

Examination  of  the  Matter  found  in  the  Retort. 

THE  matter  which  remains  in  the  retort  after  the  operation,  is,  as  we  have  remarked,  of 
a  beautiful  black,  and,  when  examined  as  to  quantity,  it  is  found  to  weigh  more  than  the 
a-lumine  alorre» 

It  confifls  of  carbone  very  accurately  mixed  with  the  alumine,  and  accordingly  the  pow- 
der is  extremely  fine. 

In  order  to  feparate  the  carbone  from  the  alumine,  and  leave  It  in  a  ftate  of  purity,  the 
alumine  mull  be  faturated  with  an  acid.  For  this  purpofe  the  fulphuric  acid  is  to  be  ap- 
plied in  the  diluted  (late.  This  acid  diflolves  the  alumine,  and  leaves  the  carbone  difen- 
gaged,  which  may  be  feparated  and  dried  upon  the  filtre.  The  fulphat  of  alumine  may 
be  obtained  by  concentrating  the  fluid  in  cryftals,  if  a  fmall  portion  of  alkali  be  added. 

The  intimate  combination  of  the  carbone  with  alumine  led  me  to  fufpeft  that  this  me- 
thod might  probably  be  advantageous  to  obtain  the  carburet  of  alumine,,  a  preparation  hi- 
therto attempted  without  fuccefs,  and  confequently  unknown  to  chemilts. 

I  therefore  thought  it  neceffary  to  repeat  the  experiment. 

I  took  an  indeterminate  quantity  of  this  kind  of  carburet  of  alumine,  which  I  placed 
under  a  glafs  veflel  filled  with  diftilled  water,,  which  veflTel  was  inverted  over  another  veiTel 
filled  with  water. 

At  the  end  of  a  certain  time  bubbles  of  air  were  difengaged,  which  rofe  to  the  upper 
part  of  the  vtfi'el,  and  gradually  difappeared.  The  water  in  the  veflel  became  deprefled, 
and  was  replaced  by  two  gafes,  one  of  which  had  all  the  charadlers  of  the  carbonic  acid- 
gas,  and  the  other  was  inflammable,  and  proved  to  be  hydrogen. 

This  experiment  confequently  proves,  that  a  fmall  portion,  of  the  water  was  decom- 
pofed,,  its  oxigeo  having  feized  the  carbone,  and  formed  carbonic  acid,  while  the  liydrogen- 
became  difengaged. 

Notwithftanding  the  accuracy  of  this  experiment,  it  is  infuflicient  to  prove  that  an  inti- 
mate combination  had  taken  place ;  or,  in  a  word,  that  a  true  carburet  of  alumine  had 
been  formed.    Neverthelefs,  until  experiments  Ihall  have  eftabliflied  the  characters  which 

ought 


On  Camphor  and  the  Camphoric  /fciJ,  IOC 

ought  to  didingulfli  an  earthy  carburet,  particularly  that  of  alumine,  I  (hall  apply  this  name 
to  dillinguifli  the  refult  of  the  new  produ£l  obtained  by  the  decompofition  of  camphor. 

We  cannot  have  any  further  doubt  rcfpeSmg  the  exiftence  of  carbone  in  camphor ; 
but  we  fliould  render  this  objeft  much  more  interefting,  if  we  could  prove  our  aflertion  by 
fyntheds.  Vegetables  do  not,,  however,  in  all  cafes,  permit  us  to  imitate  Nature  in  her 
proceflcs.  It  frequently  happens,  that  thebeft  produces  of  Art  are  but  imperfedl  approxi- 
jnations  to  natural  compounds. 

I  do  not,  however,  defpair  of  our  forming  camphor  hereafter  by  means  of  a  volatile  oiU 
Various  eflays  on  the  contrary  allow  me  to  aflert  that  it  is  poffible  to  effedt  this. 

A.  few  experiments  which  follow  will  render  this  aflertion  probable. 

SECTION   V.  ' 

Procejfes  for  carbonizing  a  Volatile  Oil. 

ONE  ounce,  or  30,571  grammes  of  carburet  of  pot-alh,  or  pot-afli  fufed  with  charcoal,, 
and  4  ounces,  or  122,284  grammes  of  volatile  oil  of  turpentine,  or  other  volatile  oil,  were 
taken.  Thefe  two  fubftances  were  put  into>a  matrafs,  and  the  whole  was  macerated  by  a 
gentle  heat^  The  oil  acquired  a  very  deep  black  colour ;  its  fmell  was  clianged  and  be- 
came more  aromatic.  If  in  thefe  experiments  the  oil  thus  changed  be  poured  into  diftil- 
led  water,  the  fluid  becomes  white,  and  a  precipitate  is  formed.  If  the  liquor  be  left  in 
conta£l  with  the  atmofjjheric  air,  a  few  drops  of  oil  rife  and  float  at  the  furface,  but  the 
liquor  continues  white.  From  a  perfuafion  that  this  combination  had  formed  a  faponule, 
I  feturated  the  pot-a(h  with  an  acid,,  and  no  true  oil  was  feparated,  but  it  remained  fuC- 
pended  in  the  water,  which  was  become  opaque  and  white. 

As  the  addition  of  pot-a(h  rendered  my  experiment  uncertain,  I  repeatedlt  in  another 
manner. 

By  the  advice  of  Cit.  Guyton,  I  pafled  hydrogen  gas  (obtained  by  the  a£lion  of  ful- 
phuric  acid  upon  zinc)  through  oil  of  turpentine,  into  which  I  had  put  the  powder  of 
charcoal.  I  was  careful  to  keep  the  oil  confl:antly  hot,.in  order  to  promote  thefolution  of 
the  coal  by  the  hydrogen  gas. 

In  proportion  as  the  gas  was  difengaged,  the  fluid  became  deeper  coloured ;  and,  in- 
ftcad  of  continuing  limpid,  it  became  yellow,  and  at  laft  brown.  If  the  pneumato-chemi- 
cal  apparatus  be  adapted  to  the  veflel  containing  the  oil,  hydrogen  gas  is  colleded  toge- 
ther with  a  fmalL  portion  of  carbonic  acid. 

The  oil  by  this  treatment  has  therefore  taken  up  a  fmall  quantity  of  carbone  and  hydro- 
gen, as  appears  by  the  difl^erence  between  its  properties  and  thofe  of  pure  oil;  viz.  i.  It: 
is  deeper  coloured :  2.  Its  fmell  is  more  agreeable,  (fuave) :.  3.  And,  when  mixed  with 
water,  this  fluid  becomes  turbid,  and  the  oil  does  not  feparate  but  by  expofure  to  the  air,, 
which  leaves  the  water  conftantly  opaque. 

It  muft  be  admitted  that  thefe  trials  afford  no  fatisfaftory  refult.  But  I  have  no  doubt- 
but  that  a  continued  fet  of  experiments  on  this  objeft  would  afford  decided  conclufions,  or 
at  leaft  fome  elucidations  of  utility  to  the  progrefs  of  fcience. 

[The  remainder-  ia  our  nexti  j 

II.  In* 


90X  ManufaRui^t  tf  Call  ZieeK 


11. 

InJlruB'ions  concerning  the  ManufaElure  of  Steel,  and  its  Vfes.     By  VaSDERMONDE-,  Monge, 
and  BeRTHOLLET.     Publijhed  by  Order  of  the  Committee  of  Public  Safety. 

[Concluded  from  VoL  ii.  p.  70.] 


c 


Of  Cajl  Steel. 


AST  Steel  is  produced  by  fufion  of  natural  fteel,  particularly  that  of  cementation. 
The  fluid  ftate  aflumed  by  the  metal  in  this  operation  caufes  the  flaws  and  veins  to  difap- 
pear,  and  renders  the  whole  mafs  more  uniform. 

According  to  the  defcription  which  Jars  has  given  us  of  the  manner  in  which  this  ope- 
ration is  performed  at  Sheffield,  all  kinds  of  fragments  of  broken  fteel  are  ufed.  The  fur- 
nace is  of  the  fame  kind  as  that  of  the  brafs-founder,  but  much  fmaller,  and  fupplied  with' 
air  by  a  fubterraneous  communication.  At  the  mouth  of  the  furnace,  which  is  fquare, 
and  level  with  the  earth,  there  is  an  opening  againft  a  wall  where  a  chimney  is  carried  up. 
Thefe  furnaces  contain  only  one  large  crucible  nine  or  ten  inches  high,  and  fix  or  feven  in 
diameter.  The  fteel  is  put  into  the  crucible  with  a  flux,  the  compofition  of  which  is  kept 
fecret :  and  the  crucible  itfelf  is  placed  on  a  round  brick  ftanding  on  the  grate.  Coak  is 
placed  round  the  crucible,  and  the  upper  part  of  the  furnace  is  filled  with  it.  It  is  then 
fet  on  fire  ;  and  the  upper  opening  of  the  furnace  is  entirely  clofed  by  a  covering  formed 
of  bricks,  bound  together  with  iron. 

The  crucible  remains  five  hours  in  the  furnaCc  before  the  fteel  is  perfe£liy  fufed.  Se- 
veral operations  are  afterwards  made.  Moulds  formed  of  two  pieces  of  caft  iron,  which 
fit  together,  and  form  an  odtagonal  or  fquare  cavity,  are  prepared  for  cafting  the  fteel, 
which  is  afterwards  hammered  out  in  the  fame  manner  as  blifter-fteel,  but  with  lefs  heat 
and  more  care,  becaufe  of  the  danger  of  breaking  it. 

Chalut,  officer  of  artillery,  has  made,  experiments  on  the  flux  which  is  beft  adapted  for 
making  caft  fteel.  He  is  convinced  that  every  kind  of  glafs  may  be  ufed  as  a  flux,  except 
that  which  contains  lead  or  arfenic. 

The  fteel  being  broken  into  fmall  pieces,  is  to  be  covered  with  the  glafs.  The  cover  of 
the  crucible  muft  then  be  put  on,  and  the  heat  urged  to  the  greateft  degree  of  the  brafs- 
founders  furnace. 

It  appears  that  an  extraordinary  hardnefs  is  fometimes  required  to  be  given  to  caft  fteel, 
and  that  this  efl^e£l;  is  produced  by  mixing  coaly  matter  with  the  flux,  to  faturate  the  fteel, 
and  give  it  the  higheft  degree  of  hardnefs.  It  is  probable  that  certain  inftruments  are  ma- 
nufaftured  by  fome  procefs  of  this  kind  ;  fuch  as  cylinders  and  laminating  rollers,  of  which 
the  hardnefs  is  very  great,  and  the  grain  perfeflly  uniform  through  the  whole  mafs  : — but 
on  this  fubjeft  we  have  nothing  to  offer  but  conjeftures. 

One  of  the  greateft  difficulties  we  find  in  this  country  (France)  in  the  fufion  of  fteel,  is 
to  procure  good  crucibles.  The  art  of  pottery,  which  is  truly  important  in  every  one  of  its 
parts,  is  that  which,  of  all  others,  the  moft  flrongly  folicits  our  induftry. 

6  Con- 


'    On  Sfee!  and  its  Ufir  j<j j 

Concerning  the  peculiar  Properties  of  tie  liferent  Kinds  of  Steef, 
CAST  fteel  may  be  confidered  as  the  mod  perfect  for  all  fuch  inftruments  as  require  a 
beautiful  polifli  and  uniform  hardnefs.  It  is  exempt  from  the  flaws,  dull  fpots,  and  veins, 
■which  are  more  or  lefs  abundant  in  other  fteel.  This  fteel  ought  to  be  chofen  for  fuch  tools 
as  require  to  be  hard  and  well  poliflied;  fuch  as  burnifliers,  watchmakers' tools,  lancets, 
razors,  and  ornamental  fteel-work ;  but  it  has  the  inconvenience  of  not  being  welded*  with 
iron,  and  is  brittle.  It  is  more  difficult  to  treat  in  the  fire,  and  is  neceflarily  much  dearer 
than  common  fteel,  becaufe  it  is  obtained  by  fufion  of  that  very  article. 

This  kind  of  fteel  is  highly  valuable  to  the  arts  which  promote  luxury ;  but  we  muft  dl- 
re£t  our  attention  to  the  fteel  which  forms  the  hatchet,  the  file,  the  fabre,  and  the  hammers 
of  gun-locks. 

Steel  of  cementation  fomctimes  approaches  to  caft  fteel  in  purity,  when  excellent  iron  has 
been  ufed,  and  particularly  when  it  has  been  well  forged ;  but  in  general  it  prefents  fome 
threads  and  veins,  is  lefs  uniform  in  its  texture,  and  does  not  become  equally  hard.  This 
fteel  may  be  ufed  for  moft  articles  of  cutlery,  edge-tools,  laminating  rollers,  hammers,  fmall 
fprings,  files,  &c.     It  is  not  eafily  welded  to  iron. 

This  fteel  is  not  only  ufed  for  a  great  variety  of  objedts,  but  it  may  be  ufed  in  different 
proportions  in  the  ftufFs  (EtofFesf )  which  are  ufed  when  a  material  is  required  which  fhall  be 
lefs  fubje£l  to  break,  as  in  the  fabrication  of  large  fprings,  fcythes,  fabres,  &c. 

The  material  called  ftufF(EtofFe)  is  a  compound  of  iron  and  fteel,  feveral  plates  of  which 
are  forged  and  welded  together,  to  afford  a  fubftance  partaking  of  the  properties  of  both. 
The  iron  feems  to  give  flexibility  to  the  fteel,  while  this  communicates  its  hardnefs  and 
elafticity  to  the  iron.  It  appears  that  the  art  of  uniting  plates  of  fteel  and  iron,  and  of  con- 
torting them  together,  is  the  principal  requifite  in  the  perfeftion  of  Damafcus  fteel. 

Natural  fteel  is  much  lefs  uniform  than  the  fteel  of  cementation.  When  it  is  polifhed,, 
its  furface  is  ufually  rendered  unequal  by  fcabrous  places,  flaws  or  veins.  It  is  eafy  to  dif- 
cover  veins  of  iron  with  the  point  of  the  graver,  fo  that  it  may  be  confidered  as  a  natural 
compofition  ;  whence  it  is  found,  that  cutting  tools  made  of  this  fteel  are  lefs  fubjedt  to  fail 
in  the  edge,  and  that  it  bears  heating  a  fecond  time  very  well ;  having,  as  the  workmen  fay, 
more  body,  and  being  more  eafy  to  forge. 

In  general,  according  to  our  eminent  cutler Perret,  It  is  advifeable  to  ufe  the  Englifli  ce- 
mented fteel  for  fine  and  delicate  work,  and  fometimes  even  caft  fteel ;  but  for  ftrong  and 
heavy  work,  the  preference  is  to  be  given  to  German  fteel,  which  is  the  natural  fteel,  be- 
caufe it  has  more  body  and  tenacity. 

Upon  the  whole,  it  appears  to  us  that  the  fteel  of  cementation  is  moft  worthy  of  being, 
attended  to  •,  becaufe  it  is  eafy,  at  a  fmall  charge,  to  eftablifh  nianufa£tories  on  a  confined: 
fcale,  and  with  the  deCred  expedition  ;  and  becaufe  this  fteel  may,  without  difficulty,  be 
ufed  in  any  kind  of  work.  Fellow  citizens,  let  us  convey  to  our  forges  thofe  expenfive  ba* 
luftrades  and  railing,  which  have  nothing  to  defend;  and  if  we  find  them  to  poffefs  the  q^a- 
lities  of  good  iron,,  let  us  convert  them  into  fteel. 

•  For  th«  method  of  welding  caft-fteel  to  iron,  fee  PKilof.  Jour.  I.  575.  N. 
t  I  am  not  aquaimed  with  the  appropriate  £nglijh  term.  N. 


104  Tropert'ies  bf  Steel.  - %?  i_y  If^Ufm  Ac'd. 

The  Method  of  trying  Steel. 

THE  different  properties  belonging  to  each  kind  of  ileel  render  the  proofs  of  their  qualitf 
difficult  even  to  (kilful  workmen.  Caft  fteel  will  be  thought  of  a  very  bad  quality  by  him 
who  is  not  in  the  habit  of  working  it ;  as  will  likewife  the  fteel  of  cementation  by  the 
workman  who  is  commonly  employed  upon  German  fteel.  The  grain  of  the  frafture  is  a 
deceitful  indication,  becaufe  its  finenefs  varies  with  its  hardnefs  ;  neverthelefs  good  fteel 
ought  always  to  exhibit  an  even  grain.  Caft  fteel  ought  to  take  a  good  polifli,  and  not  be 
too  brittle  :  fteel  of  cementation  ought  to  afford  gravers  capable  of  refifting  percuflion  with- 
out notching  or  turning  in  the  edge  ;  natural  fteel  ought  to  weld  with  eafe  to  iron,  and 
make  good  edge-tools. 

There  are  circumftances  in  which  it  is  of  advantage  to  afcertain  whether  a  manufactured 
article  be  formed  of  fteel  or  iron  without  injuring  it.  The  means  of  doing  this  is  of  the 
more  confequence  to  us,  becaufe  certain  unprincipled  contraftors  have  delivered  fabres  with 
blades  of  pure  iron,  to  which  a  flight  degree  of  rigidity  had  been  given  in  the  fabrication  ; 
a  clrcumftance  which  has  induced  the  Committee  of  Public  Safety  to  publifti  the  dlredlions 
we  ftiall  here  tranfcribe,  and  to  oblige  Its  agents,  entrufted  with  the  reception  of  every 
kind  of  arms  of  fteel,  to  fubmit  them  to  this  proof. 

"  If  a  drop  of  nitrous  acid  be  placed  upon  the  furface  of  polllhed  iron,  and,  after  having 
left  it  two  minutes,  water  be  thrown  thereon,  this  laft  fluid  will  carry  off  the  acid  with  all 
Its  contents,  and  there  will  remain  merely  a  white  fpot,  or  the  colour  of  iron  newly 
<:leaned. 

"  If  the  fame  operation  be  made  on  a  plate  of  poliflied  fteel,  the  acid  likewife  feizes  the 
iron,  but  does  not  aft  on  the  coaly  part.  This  laft  falls  down  during  the  folution,  and 
forms  a  black  fpot,  which  the  projeftion  of  the  water  does  not  remove,  and  which  even  re- 
mains for  a  confiderable  time,  on  account  of  its  adhefion. 

"  In  order  to  fucceed  in  this  operation,  a  diluted  acid  muft  be  ufed,  becaufe  the  coaly 
principle  does  not  adhere  to  the  furface,  but  In  proportion  to  the  flownefs  of  the  folution, 
and  the  weaknefs  of  the  effervefcencc. 

"  If  pure  or  reclified  nitrons  acid  be  not  at  hand,  the  aquafortis  of  commerce  may  be 
ufed,  taking  care  to  dilute  it  in  a  certain  degree. 

"  The  drop  of  acid  muft  be  conveyed  with  a  ftick  of  glafs,  or  other  material,  which  is 
liot  itfelf  attacked,  and  cannot  afford  any  thing  capable  of  changing  the  refult. 

"  The  fmallcft  drop  fuffices.  It  ought  rather  to  be  fpread  out,  than  kept  together,  that 
it  may  mark  a  larger  furface.  The  ftopper  of  a  very  fmall  bottle,  in  which  the  acid  is  kept, 
anfwers  this  purpofe  very  well. 

*'  After  having  made  this  proof  two  or  three  times  on  iron  and  fteel  compared  with  each 
other,  the  operator  will  be  enabled  to  fpeak  with  certainty  refpedling  the  difference  of  the 
metals." 

Artlfts  have  long  fince  availed  themfelves  of  a  method  of  this  kind  to  diftinguini  Damaf- 
Cus  blades.  Thefe  blades,  as  we  have  obfer\'ed,  are  compofed  of  the  fteel  and  iron  inti- 
mately mixed.  By  this  proof,  fays  Perret,  they  prefent  ferpentine  veins,  fome  of  a  whitifli 
grey,  others  of  a  deep  grey,  and  others  blackifh,  which  are  known  by  the  name  of  the 

yiowers  of  Damafcus. 

We 


Properties  of  Steel,--Hard  cojl  inn,  roj 

Wc  have  remarked  that  caft  iron,  fufficiently  abounding  with  charcoal,  aflumes  the  ap- 
pearance of  the  white  crude  iron  when  it  is  caft.  in  plates  or  too  fuddenly  cooled.  To  af- 
certain  its  nature,  nothing  more  is  neceflary  than  to  clean  its  furface  j  and  by  the  more  or 
lefs  grey  or  dark  colour  of  the  fpot  produced  by  nitrous  acid,  a  judgment  may  be  formed  of 

its  quality. 

Vandermonde,  Monge,  Berthollet. 

Annotations  upon  the  Report  concerning  Steel. 

I.  Notwithstanding  the  great  light  which  has  been  afforded  by  the  labours  of  Rinman, 
Bergman,  Vauquelin,  and  other  chemifts,  together  with  the  learned  authors  of  the  fore- 
going paper,  we  have  ftill  much  to  learn  refpefling  the  caufes  of  th^  feveral  qualities  of 
fteel  to  be  found  in  the  market.  Much  of  this  information  might  probably  be  obtained  by 
diligent  enquiry,  and  the  ufual  methods  of  examination.  It  is  yet  to  be  fliewn  by  experi- 
ment, whether  pure  iron  united  with  carbon  conflitutes  the  beft  fteel  ;  or  whether  any  ad- 
ditional ingredient,  fuch  as  phofphorus,  manganefe,  or  other  metallic  matter,  may  not  be  of 
advantage.  If  the  former  pofition  be  true,  the  beft  fteel-iron  will  be  that  which  is  the 
pureft;  and  the  beft  cement  will  be  the  fimpleft  coaly  matter.  On  the  contrary,  if  the  latter 
fuppofitions  fliould  be  well  founded,  the  goodnefs  of  our  fteel  will  depend,  not  only  upon 
the  component  parts  of  the  bar  iron,  but  likewlfe  on  the  adaptation  of  the  cement  proper 
for  its  converfion.  Mr.  Duhamel,  in  tlie  Encyclopedic,  article  Acier,  p.  462,  found  that 
the  charcoal  which  had  been  ufed  in  making  fteel  was  not  fit  to  be  ufed  again,  by  reafon  of 
the  flownefs  of  its  operation.  In  this  cafe  it  feems  probable  that,  though  enough  of  car- 
bone  remained,  yet  fonie  more  volatile  ingredient  had  been  expended  in  the  firft  procefs. 
Our  authors  have  well  explained  the  advantage  of  the  iron  being  well  forged  and  found 
throughout,  previous  to  its  expofure  to  the  cementing  procefs.  • 

1.  The  grey  crude  iron  may  be  confidered  as  iron  faturated  with  as  much  plumbago  or 
carburet  as  it  can  hold  in  folution  at  a  very  elevated  temperature.  When  it  is  fuffered  to 
cool  flowly,  as  in  foft  cafting,  the  plumbago  appears  to  feparate  by  hafty  cryftallization 
tlirough  the  whole  mafs,as  may  frequently  be  obferved  in  its  fracture,  and  as  has  been  fliewn 
by  plunging  a  cold  bar  of  iron  into  the  fufed  metal,  and  withdrawing  it  covered  with  the 
carburet  which  precipitates  upon  it.  When  this  iron  is  poured  into  a  cold  mould  of  me- 
tal, or  fuffered  to  run  to  a  great  diftance  from  the  aperture  of  reception,  in  fand,  or  other- 
wife  if  a  bar  of  this  metal  be  heated  to  whitenefs,  and  plunged  in  water,  it  becomes  very 
h»rd  ;  more  fo  than  fteel  tools  of  any  defcription  are  ufually  made,  and  is  very  white,  and 
clofer  grained  in  its  fracture.  .The  hardnefs  muft  depend  upon  circumftances  in  its  aggre- 
gation, to  explain  which  we  pofiefs  no  data  ;  but  I  apprehend  the  whitenefs  to  be  an  evi- 
dent confcquence  of  the  union  between  the  iron  and  the  plumbago  continuing  to  be  nearly 
as  intimate  as  it  was  at  the  white  heat.  It  is  very  probable  that,  in  all  cafes  of  the  hardening 
of  other  fteels  containing  lefs  carbone,  a  iimilar  efFefl  may  take  place. 

3.  The  laminating  rollers,  concerning  which  our  authors  offer  nothing  but  conjeiSlure, 
are  made  cf  this  iron  caft  in  fand,  or  metallic  moulds  of  confiderable  thicknefs.  I  am  in- 
formed by  founders  who  make  them,  that  the  external  hard  part  does  not  penetrate  to  a 
greater  depth  than  about  three  quarters  of  an  inch  ;  and  that  the  hardnefs  is  not  greater 
than  that  of  a  good  graver.    The  procefs  of  turning  them  in  the  lathe.,  iu  faQ,  ftiews  this. 

Vol.  JI.— June  1798.  V  Far 


Ib6  Propel  ties  of  SUe/. — Flcat  excited  by  Frlifk/i; 

For  tlicy  are  turned  by  an  extremely  flow  motion,  with  a  tool  fcledcJ  from  the  general 
ilock  in  the  work-fliop,  becaufe  the  greater  number  even  of  good  gravers  will  not  cut  it.   ' 

4.  Thoi'e  who  forge  fteel  know  that  it  is  very  eafily  degraded  in  the  lire.  If  a  fmall 
piece,  for  example,  half  a  cubic  inch,  of  grey  crude  iron  be  put  into  a  common  fire,  and. 
kept  red-hot  for  about  half  an  hour,  and  at  the  expiration  of  that  time  the  heat  be  fuddenr- 
ly  ralfed  to  whitenefs  by  the  bellows  ;  the  internal  or  fteely  part  will  break  its  way  ^through 
the  external  cruft,  which  is  converted  into  common  iron,  and  rendered  much  lefs  fufible. 
This  cruft,  or  hollow  fliell,  may  then  be  taken  out  of  the  fire.  All  fteel  becomes  degraded 
in  the  fame  manner,  even  by  very  careful  heating.  Caft-fteel,  drawn  into  fmall  bars,  ex- 
hil^its  cloudy  lines  and  veins  on  its  furface  when  tried  by  an  acid,  which  no  doubt  have  been 
produced  during  the  heating  and  forging. 

5.  Caft-flcel  being  made  out  of  broken  tools  of  every  kind,  cannot  of  itfcif  poflefs  a  larger 
jlofe  of  plumbago  than  the  average  quantity  contained  in  thofe  fteels.  But  the  Englilh  caft- 
fteel  is  more  fufible  and  more  tender  under  the  hammer  than  German  fteel,  or  the  fteel  of 
cementation  ;  which  circumftances  appear  to  indicate  that  it  contains  more  plumbago  :  and-* 
the  truth  of  this  induftion  is  confirmed  by  its  exhibiting  a  much  darker  fpot  than  other 
fteels,  when  tried  by  an  acid.  Chalut  did  not  therefore  make  this  kind  of  fteel  when  he 
ufed  glafs  only  for  his  flux.  It  cannot  be  doubted  but  that  the  flux  of  our  manufafturers 
muft  contain  charcoal,  at  leaft.  If  it  be  animal  coal,  which  is  moft  probable,  it  will  alfo  con- 
tain phofphorus ;  an  ingredient  to  which  the  fuperiority  of  this  coal,  in  cafcThardening,  13 
probably  owing. 

6.  Tenacity  and  hardnefs  are  very  frequently  confidered  as  if  they  were  one  and  the 
fame  quality  with  regard  to  implements  and  tools,  though  they  are  certainly  very  diftinck 
properties.  Tenacity  is  the  oppofite  to  friability  or  brittlenefs  ;  hardnefs  is  the  oppofite 
to  foftnefs.  It  is  probable  that  iron  is  more  tenacious  than  fteel,  and  ifr-is  certain  that  foft 
fteel  is  more  tenacious  than  hard.  Where  tenacity  and  no  confiderable  degree  of  hardnefs  - 
are  wanting,  as  in  fprings,  the  inferior  fteels,  or  the  compounds  of  fteel  and  iron,  will  afford  ' 
a  more  fafe,  and  confequently  in  many  inftances  more  ufeful  article  ;  but  where  hardnefs 
and  tenacity  are  both  required,  the  leading  quality  of  the  fteel  muft  be  its  uniformity.  C^ft 
fteel  is  preferred  in  England  to  every  other  kind,  not  only  for  polifhed  fteel-work  and  the 
beft  cutting  tools,  but  likewife  for  cold  chifels,  and  the  hard  gravers  for  turners  in  metal ; 
in  both  which  laft  I  have  obferved,  by  confiderable  experience,  that  the  common  opinion  is 
well  founded. 


III. 

yin  Enquiry  concerning  the  Source  of  the  Heat  which  is  excited  hy  Frisian*.     By  BENJAMiNi 
Count  of  RuMFORD,  F.R.S.  M.R.I.  J. 

At  frequently  happens  that,  in  the  ordinary  affairs  and  occupations  of  life,  opportunities 
prefent  themfelves  of  contemplating  fome  of  the  moft  curious  operations  of  nature  ',  and 

•  From  the  Philofophical  Tranfaftions,  I798.~-Read  January  25,  1798. 

Tcry 


Heat  excited  in  boring  Cannon>  -  -tpj 

■yery  Interefting  philofopliical  experiments  might  often  be  made,  almoft  without  troubie»-o^ 
-expence,  by  means  of  machinery  contrived  for  the  mere  mechanical  purpofes  of  the  arts  and 
manufactures. 

I  have  frequently  had  occafion  to  make  this  obfervation  ;  and  am  perfuaded,  that  a  habit 
of  keeping  the  eyes  open  to  every  thing  that  is  going  on  in  the  ordinary  courfe  of  the  bufi- 
nefs  of  Hfe,  has  oftener  led,  as  it  were  by  accident,  or,  in  the  playful  excurfions  of  the  ima- 
gination put  into  aftion  by  contemplating  the  moft  common  appearances,  to  ufeful  doubts 
and  ferviceable  fchemes  for  inveftigation  and  improvement,  than  all  the  more  intenfe  me- 
ditations of  philofophers  in  the  hours  cxprefsly  fet  apart  for  ftudy. 

It  was  by  accident  that  I  was  led  to  make  the  experiments  of  which  I  am  about  to  give 
an  account ;  and  though  they  are  not,  perhaps,  of  fuflicient  importance  to  merit  fo  formal 
an  introdudlion,  I  cannot  help  flattering  myfelf  that  they  will  be  thought  curious  in  feveral 
refpefls,  and  worthy  of  the  honour  of  being  made  known  to  the  Royal  Society. 
'  Being  engaged,  lately,  in  fuperintending  the  boring  of  cannon  in  the  workfliops  of  the 
military  arfenal  at  Munich,  I  was  ftruck  with  the  very  confiderable  degree  of  heat  which  a 
•brafs  gun  acquires  in  a  (liort  time  in  being  bored,  and  with  the  more  intenfe  heat  (much* 
greater  than  that  of  boiling  water,  as  I  found  by  experimerit)  of  the  metallic  chips  feparated 
from  it  by  the  borer. 

The  more  I  meditated  on  thefe  phenomena,  the  more  they  appeared  to  me  to  be  curious 
and  intercfling.  A  thorough  invedigation  of  them  feemed  even  to  bid  fair  to  give  a  farther 
infight  into  the  hidden  nature  of  heat ;  and  to  enable  us  to  form  fome  reafonable  conjeflures 
refpefling  the  exiftence  or  non-exiftence  of  an  igneous  Jluid :  a  fubjecSl  on  which  the  opinions 
of  philofophers  have  in  all  ages  been  much  divided. 

In  order  that  the  Society  may  have  clear  and  diftin£l:  ideas  of  the  fpeculations  and  reafon- 
ings  to  which  thefe  appearances  gave  rife  In  my  mind,  and  alfo  of  the  fpecific  objects  of 
philofophical  invedigation  they  fuggefted  to  me,  I  mufl:  beg  leave  to  (late  them  at  fom^ 
length,  and  in  fuch  manner  as  I  fliall  think  bed  fuitcd  to  aiifwer  this  purpofe. 

From  whence  cemej  the  heat  adlually  produced  in  the  mechanical  operation  above  men- 
tioned ? 

Is  it  fumllhed  by  the  metallic  chips,  which  are  feparated  by  the  borer  from  the  folid 
jn^fs  of  metal  ?  ^ 

If  this  were  the  cafe,  then,  according  to  the  modern  dotlrines  of  latent  heat  and  of  calo,?,, 
ric,  the  capacity  for  heat  of  the  parts  of  the  metal  fo  reduced  to  chips,  ought  not  only  to  be 
changed,  but  the  change  undergone  by  them  (liould  be  fufBciently  great  to  account  for  all 
the  heat  produced. 

But  no  fuch  change  had  taken  place;  for  I  found,  upon  taking  equal  quantities  by 
■weight  of  thefe  chips,  and  of  thin  flips  of  the  fame  block  of  metal,  feparated  by  means  of 
a  fine  faw,  and  putting  them  at  the  fame  temperature  (that  of  boiling  water)  into  equal 
<juantities  of  cold  water  (that  is  to  fay,  at  the  temperature  of  59!*'  F.),  the  portion  of  water 
into  which  the  chips  were  put  was  not,  to  all  appearance,  heated  either  lefs  or  more  thaa 
the  other  portion  into  which  the  flips  of  metal  were  put. 

■  This  experiment  beingrejieated  feveral  times,  the  refalts  were  always  fo  nearly  the  fame, 

P  2  ■  that 


108  Experiments  to  Jhew  thai  Heat  excited  iy  Friliion 

that  I  could  not  determine  whether  any,  or  what  change  had  been  produced  In  the  metaly 
in  regard  to  its  capacity  for  heat,  by  being  reduced  to  chips  by  the  borer*. 

From  hence  it  is  evident,  that  the  heat  produced  could  not  poflibly  have  been  furnifhed 
at  the  expence  of  the  latent  heat  of  the  metallic  chips.  But,  not  being  willing  to  reft  fatif- 
fied  with  thefe  trials,  however  conclufive  they  appeared  to  me  to  be,  I  had  recourfe  to  the 
following  dill  more  decifive  experiment. 

Taking  a  cannon  (a  brafs  fix  pounder)  caft  folid,  and  rough  as  it  came  from  the  foun- 
dry, (fee  fig.  I,  plate  V)  and  fixing  it  (horizontally)  in  the  machine  ufed  for  boring,  and  at 
the  fame  time  finifhing  the  outfide  of  the  cannon  by  turning,  (fee  fig.  2.)  I  caufed  its  ex- 
tremity to  be  cut  ofF,  and,  by  turning  down  the  metal  in  that  part,  a  folid  cylinder  was 
formed,  7f  inches  in  diameter,  and  9  ?^  inches  long  ;  which,  when  finiflied,  remained  joined 
to  the  reft  of  the  metal  (that  which,  properly  fpeaking,  conftituted  the  cannon,)  by  a  fmall 
cylindrical  neck,  only  ^\  inches  in  diameter,  and  ^-rs  inches  long. 

This  ftiort  cylinder,  which  was  fupported  in  its  horizontal  pofuion,and  turned  round  its 
axis,  by  means  of  the  neck  by  which  it  remained  united  to  the  cannon,  was  now  bored  with, 
the  horizontal  borer  ufed  in  boring  cannon ;  but  its  bore,  which  was  3.7  inches  in  diameter, 
inftead  of  being  continued  through  its  whole  length,  (9.8  inches)  was  only  7.2  inches  in 
length;  fo  that  a  folid  bottom  was  left  to  this  hollow  cylinder,  which  bottom  was  2.<S 
inches  in  thicknefs. 

This  cavity  is  reprefented  by  dotted  lines  in  fig.  2 ;  as  alfo  In  fig.  3,  where  the  cylinder  is 
reprefented  on  an  enlarged  fcale. 

This  cylinder  being  defigned  for  the  exprefs  purpofe  of  generating  heat  by  friftion,  by 
having  a  blunt  borer  forced  againft  its  folid  bottom  at  the  fame  time  that  it  Ihouldbe  turned, 
round  its  axis  by  the  force  of  horfes,  in  order  that  the  heat  accumulated  in  the  cylinder 
might  from  time  to  time  be  meafured,  a  fmall  round  hole,  (fee  d,  e,  fig.  3.)  0.37  of  an  inch 
only  in  diameter,  and  4.2  inches  in  depth,  for  the  purpofe  of  introducing  a  fmall  cylindrical 
mercurial  thermometer,  was  made  in  it,  on  one  fide,  in  a  direflion  perpendicular  to  the  axis, 
of  the  cylinder,  and  ending  in  the  middle  of  the  folid  part  of  the  metal  which  formed  the 
bottom  of  its  bore. 

*  As  thefe  experiments  are  important,  it  may,  perhaps,  be  agreeable  to  the  Society  to  be  mad«  acquainted 
yith  them  in  their  deiails.     One  of  them  was  as  follows  i 

To  4590  grains  of  water,  at  the  temperature  of  59^*?".  (an  allowance  or  compenfation,  reckoned  in  waterj 
for  the  capacity  for  heat  of  the  containing  cylindrical  tin  velTel,  being  included)  were  added  ioi6i  grains  of 
gun-metal  in  thin  flips,  feparated  from  the  gun  by  means  of  a  fine  faw,  being  at  the  temperature  of  210°  F. 
When  they  had  remained  together  1  minute,  and  had  been  well  ftirpcd  about  by  meant  of  a  fmall  rod  of  light- 
wood,  the  heat  of  the  mixture  was  found  to  be  z=.  63°. 

From  this  experiment,  the  fpecific  heat  of  the  metal,  calculated  according  to  the  rule  given  by  Dr.  Crawford, 
turns  out  to  be  =:  o.iioo,  that  of  water  being  =  i.ooo. 

An  experiment  was  afterwards  made  with  the  mctalUc  chips,  as  follows : 
'  To  the  fame  quantity  of  water  as  was  ufed' in  the  experiment  above  mentioned,  at  the  fame  temperature, 
(viz.  59i°,)  and  in  the  fame  cylindrical  tin  veffel,  were  now  put  ioi6j-  grains  of  metallic  chips  of  gun-metal, 
bored  out  of  the  fame  gun  from  which  the  flips  ufed  in  the  foregoing  experiment  were  taken,  and  at  the  fame 
temperature  (zio°.)  The  heat  of  the  mixture,  at  the  end  of  i  minute,  was  juft  63°,  as  before;  confequemly 
the  fpecific  heat  of  thefe  metallic  chips  was  =  o.noQ.  Each  of  the  above  eXperimeius  was  repeated  three 
liaiM,  and  ahvays  with  nearly  the  fame  refultt. 

The 


//  ntf  the  Confequenet  if  Change  of  Capaeity,  1 05 

The  folld  contents  of  this  hollow  cylinder,  exclufive  of  the  cylindrical  neck  by  which  it 
remained  united  to  the  cannon,  were  385+- cubic  inches,  Englifh  meafure,  and  it  weighed 
1 1 3. 13  lb.  avoirdupois,  as  I  found  on  weighing  it  at  the  end  of  the  courfe  of  experiments 
made  with  it,  and  after  it  had  been  feparated  from  the  cannon  with  which,  during  the 
experiments,  it  remained  conneQed  *. 

Experiment  No.  I. 

THIS  experiment  was  made  in  order  to  afcertain  how  much  heat  was  adtually  gene- 
rated by  fridtion,  when  a  blunt  fteel  borer  being  fo  forcibly  fhoved  (by  means  of  a  ftrong 
fcrew)  againft  the  bottom  of  the  bore  of  the  cylinder,  that  the  preflure  againft  it  was  equal 
to  the  weight  of  about  1 0,000  lb.  avoirdupois,  the  cylinder  was  turned  round  on  its  axis 
(by  the  force  of  horfes)  at  the  rate  of  about  32  times  in  a  minute. 

This  machinery,  as  it  was  put  together  for  the  experiment,  is  reprefented  by  fig.  2. 
W  is  a  ftrong  horizontal  iron  bar  connected  with  proper  machinery  carried  round  by 
horfes,  by  means  of  which  the  cannon  was  made  to  turn  round  its  axis. 

To  prevent,  as  far  as  poITible,  the  lofs  of  any  part  of  the  heat  that  was  generated  in  the 
experiment,  the  cylinder  was  well  covered  up  with  a  fit  coating  of  thick  and  warm  flannel, 
which  was  carefully  wrapped  round  it,  and  defended  it  on  every  fide  fiom  the  cold  air  of 
the  atmofphere.  This  covering  is  not  reprefented  in  the  drawing  of  the  apparatus, 
fig.  2. 

I  ought  to  mention,  that  the  borer  was  a  flat  piece  of  hardened  fteel,  0.63  of  an.  inch 
thick,  4  inches  long,  and  nearly  as  wide  as  the  cavity  of  the  bore  of  the  cylinder,  namely, 
3f  inches.  Its  corners  were  rounded  off  at  its  end,  fo  as  to  make  it  fit  the  hollow  bottom 
of  the  bore  ;  and  it  was  firmly  fattened  to  the  iron  bar  (m),  which  kept  it  in  its  place.  The 
area  of  the  furface,  by  which  its  end  was  in  conta£l  with  the  bottom  of  the  bore  of  the 
cylinder,  was  nearly  2^  inches.  This  borer,  which  is  diftinguiftied  by  the  letter  n,  is  re- 
prefented in  moft  of  the  figures. 

At  the  beginning  of  the  experiment,  the  temperature  of  the  air  in  the  fhade,  as  alfo 
that  of  the  cylinder,  was  juft  60°  F. 

At  the  end  of  30  minutes,  when  the  cylinder  had  made  960  revolutions  about  its  axis, 
the  horfes  being  ftopped,  a  cylindrical  mercurial  thermometer,  whofe  bulb  was  -j^^  of  an 
inch  in  diameter,  and  3^  inches  in  length,  was  introduced  into  the  hole  made  to  receive 
it,  ia  the  fide  of  the  cylinder  j  when  the  mercury  rofe  inftantly  to  130*. 

Though  the  heat  could  not  be  fuppofed  to  be  quite  equally  diftributed  in  every  part  of 
the  cylinder,  yet,  as  the  length  of  the  bulb  of  the  thermometer  was  fuch  that  it  extended 

*  For  fear  T  fliould  be  fvifpe£led  of  prodigality  in  the  profeciiticn  of  my  philofophical  rcfuarches,  I  think  it 
jieccffary  to  ijiform  the  Society,  that  the  cannon  I  made  ufe  of  in  this  experiment  was  not  facrificed  to  ir. 
The  fliort  hollow  cylinder  which  was  formed  at  the  end  of  it,  was  turned  out  of  a  cylindrical  mafs  of  metal 
about  two  feet  in  length,  projefting  beyond  the  muzzle  of  the  gun,  called  in  the  German  language  the  verj- 
lorncr  kopf,  (the  head  of  the  cannon  to  be  thrown  away,)  and  which  is  reprefented  in  fig.  i. 

This  additional  projeftion,  which  is  cut  off  before  the  gun  is  bored,  is  always  caft  with  it,  in  order  that,  by 
means  of  th«  preffure  of  its  weight  on  the  metal  in  the  lower  part  of  the  mould,  daring  the  time  it  is  cooling-, 
the  gun  may  be  the  more  compaft  in  the  neighbourhood  of  the  muzzle,  where,  without  thij  precaution,  the 
Bwul  would  be  apt  to  be  porous  or  full  of  honeycombs, 

from: 


^4©  'lExptt'iments  on  Heat  excited  hy  Friclian. 

.from  flie  axis  of  the  Cylinder  to  near  its  furface,  the  heat  indicated  by  it  could  not  be  very 
different  from  that  of  the  mean  temperature  of  the  cylinder  ;  and  it  was  on  tliis  account 
-that  a  thermometer  of  that  particular  form  was  chofen  for  this  experiment. 

To  fee  how  fad  the  heat  efcaped  out  of  tlie  cylinder,   (in  order  to  be  able  to  make  a 
probable  conjefture  refpeding  the  quantity  given  off  by  it  during  the  time  the  heat  genc- 
•rated  by  the  friftion  was  accumulating,)  the  machinery  (landing  ftill,  I  fuffcred  the  ther- 
mometer to  remain  in  its  place  near  three  quarters  of  an  hour,  obferving  and  noting  dowuj 
Mt  fmall  intervals  of  time,  the  height  of  the  temperature  indicated  by  it.     Thus, 
At  the  end  of  4  minutes,  the  heat,  as  (hown  by  the  thermometer,  was      laC" 
After  5  minutes,  always  reckoning  from  the  firft  obfervation,     J  25 
At  the  end  of  7  minutes,  —  —  —  123 

12  —  —  —  —  120 

14  —  --  —  —  "9             ' 

,6  —  —  —  —  "8 

20  —  —  —  — '  J 16 

,4  —  _  —  —  115 

28  —  —  —  —  "4 

31  -  -  -  -  i'3 

34  -  -  -  -  "2 

37.  _  -  _  _  III 

And  when  41  minutes  had  elapfed  —  —  no 

Having  taken  away  the  borer,  I  now  removed  the  metallic  duft,  or  rather  fcaly  matter, 
which  had  been  detached  from  the  bottom  of  the  cylinder  by  the  blunt  fteel  borer,  in  thi« 
experiment,  and,  having  carefully  weighed  it,  I  found  its  weight  to  be  837  grains  Troy. 

Is  it  poflible  that  the  very  confiderable  quantity  of  heat  that  was  produced  in  this  expe- 
riment (a  quantity  which  aftually  raifed  the  temperature  of  above  113  lb.  of  gun-metal  at 
lead  70  degrees  of  Fahrenheit's  thermometer,  and  which,  of  courfe,  would  have  been  ca- 
pable of  melting  6^  lb.  of  ice,  or  of  caufmg  near  5  lb.  of  ice-cold  water  to  boil,)  could 
have  been  furniflied  by  fo  inconfiderable  a  quantity  of  metallic  duft  ?  and  this  merely  in 
confequence  of  a  change  of  its  capacity  for  heat  ? 

As  the  weight  of  this  duft  (837  grains  Troy)  amounted  to  no  more  than  ^^th  part  of 
that  of  the  cylinder,  it  muft  have  given  off  948  degrees  to  raife  the  temperature  of  the 
cylinder  i  degree  i  and  confequently  it  muft  have  given  off  66360  degrees  of  heat  to  have 
produced  that  of  the  experiment ! 

But,  without  infilling  on  the  improbability  of  this  fuppofitlon,  we  have  only  to  recolle£l, 
that  from  the  refults  of  a£lual  and  decifive  experiments,  made  for  the  exprefs  purpofe  of 
afcertaining  that  fa£l,  the  capacity  for  heat,  of  the  metal  of  which  great  guns  are  caft,  is 
pot  fenfibly  changed  by  being  reduced  to  the  form  of  metallic  chips,  in  the  operation  of 
boring  cannon ;  and  there  does  not  feem  to  be  any  reafon  to  think  that  it  can  be  much 
changed,  if  it  be  changed  at  all,  in  being  reduced  to  much  fmaller  pieces  by  means  of  a 
J)Orer  that  is  lefs  {harp. 

0  If 


^xperitnents  on  Heat  enclud  by  JFri^kn.  1 1* 

If  tlie  heat,  or  any  confulerable  part  of  it,  were  produced  ia  confcquence  of  a  change 
in  the  capacity  for  heat  of  a  part  of  the  metal  of  the  cylinder,  as  fuch  change  could  only 
Be  fuperficial,  the  cylinder  would  by  degrees  be  exhaulted,  or  the  quantities  of  heat  pro- 
duced, in  any  given  fhort  fpace  of  time,  would  be  found  to  diminifh  gradually  in  fuccef- 
five  experiments.  To  find  out  if  this  really  happened  or  not,  I  repeated  the  laft-men- 
tioned  experiment  feveral  times  with  the  utmofl  care  }  but  I  did  not  difcover  the  fmalleft 
fign  of  exhauftion  in  the  metal,  notwithftanding  the  large  quantities  of  heat  a(Shially  given 
off. 

Finding  fo  much  reafon  to  conclude,  that  the  heat  generated  in  thefe  experiments,  or 
excited,  as  I  would  rather  choofe  to  exprefs  it,  was  not  furniflied  at  the  expence  of  the 
latent  heat  or  combined  caloric  of  the  metal,  I  pulhed  my  enquiries  a  ftep  farther,  and  en-, 
deavoured  to  ^nd  out  whether  the  air  did  or  did  not  Contribute  any  thing  in  the  genera- 
tion of  it. 

Experiment  No.  2, 

AS  the  bore  of  the  cylinder  was  cylindrical,  and  as  the  iron  bar  (m),  to  the  end  of 
which  the  blunt  Heel  borer  was  fixed,  was  fquare,  the  air  had  free  accefs  to  the  infide  of 
the  bore,  and  even  to  the  bottom  of  it  where  the  fridion  took  place  by  which  the  heat 
was  excited. 

As  neither  the  metallic  chips  produced  in  the  ordinary  courfe  of  the  operation  of  bor-- 
ing  brafs  cannon,  nor  the  finer  fcaly  particles  produced  in  the  laft-mentioned  expsriments 
by  the  fridion  of  the  blunt  borer,  fliowed  any  figns  of  calcination,  I  did  not  fee  how  the 
air  could  poffibly  have  been  the  caufe  of  the  heat  that  was  produced  ;  but,  in  an  invefti- 
gation  of  this  kind,  I  thought  that  no  pains  fhould  be  fparcd  to  clear  away  the  rubbii'h, 
and  leave  the  fubjecSt  as  naked  and  open  to  infpecStion  as  pofTible. 

In  order  by  one  decifive  experiment  to  determine  whether  the  air  of  the  atmofphere  had 
any  part  or  not  in  the  generation  of  the  heat,  I  contrived  to  repeat  the  experiment  under 
circumftances  in  which  it  was  evidently  impqffible  for  it  to  produce  any  cffe£l  whatever.  By 
means  of  a  pifton  exa£lly  fitted  to  the  mouth  of  the  bore  of  the  cylinder,  through  the 
middle  of  which  pifton  the  fquare  iron  bar,  to  the  end  of  which  the  blunt  fteel  borer  was 
fixed,  paffed  in  a  fquare  hole  made  perfe£lly  air-tight,  the  accefs  of  the  external  air  to  the 
infide  of  the  bore  of  the  cylinder  was  effeftually  prevented.  In  fig.  3.  this  pifton  {/>)  is 
feen  in  its  place  :  it  is  likewife  fhown  in  fig.  7.  and  8. 

1  did  not  find,  however,  by  this  experiment,  that  the  exclufion  of  the  air  diminifhed  in 
the  fmalleft  degree  the  quantity  of  heat  excited  by  the  fridion. 

There  flill  remained  one  doubt,  which,  though  it  appeared  to  me  to  be  fo  flight  as 
hardly  to  deferve  any  attention,  I  was  however  defirous  to  remove.  The  pifton  which 
clofed  the  mouth  of  the  bore  of  the  cylinder,  in  order  that  it  might  be  air-tight,  was  fitted 
into  it  with  fo  much  nicety  by  means  of  collars  of  leather,  and  preffed  againft  it  with  fo 
much  force,  that,  notwithftanding  its  being  oiled,  it  occafioned  a  confiderable  degree  of 
fri£lion  when  the  hollow  cylinder  was  turned  round  its  axis.  Was  not  the  heat  produced, .. 
or  at  leaft  fome  part  of  it  occafioned,  by  the  fridlion  of  the  pifton  ?  And  as  the  external  air 
had  free  accefs  to  the  extremity  of  the  bore  where  it  came  in  contadl  with  the  pifton,  is 
it  not  poffible  that  this  air  might  have  had  fome  fliare  in  the  generation  of  the  heat  pro- 
duced ?. 

Experimeitt: 


4,u  ExpfrlmentJ  on  Heat  exelK'd  by  Frt^kn, 

Experiment  No.  3. 

A  QUADRANGULAR  oWong  dcal-box,  (fee  fig.  4.)  water-tight,  ti{-  EriglKh  inches  long, 
15/^  inches  wide,  and  9i\  inches  deep,  (meafured  in  the  clear,)  being  provided,  with  holes 
or  flits  in  the  middle  of  each  of  its  ends  juft  large  enough  to  receive  the  one,  the  fquarc 
iron  rod  to  the  end  of  which  the  blunt  fteel  borer  was  faftened,  the  other,  the  fmall  cylin- 
drical neck  which  joined  the  hollow  cylinder  to  the  cannon;  when  this  box  (which  was 
occafionally  clofed  above  by  a  wooden  cover  or  lid  moving  on  hinges)  was  put  into  its 
place  -,  that  is  to  fay,  when  by  means  of  the  two  vertical  openings  or  flits  in  its  two  ends, 
(the  upper  parts  of  which  openings  were  occafionally  clofed  by  means  of  narrow  pieces  of 
wood  Aiding  in  vertical  grooves,)  the  box  (g,  h,  i,  k,  fig.  3.)  was  fixed  to  the  machinery  ia 
fuch  a  manner  that  its  bottom  ft,  i,)  being  in  the  plane  of  the  horizon,  its  axis  coincided 
with  the  axis  of  the  hollow  metallic  cylinder  ;  it  is  evident  from  the  defcription,  that  the 
hollow  metallic  cylinder  would  occupy  the  middle  of  the  box  without  touching  it  011 
either  fide,  (as  it  is  reprefented  in  fig.  3.)  and  that  on  pouring  water  into  the  box  and  fill- 
ing  it  to  the  brim,  the  cylinder  would  be  completely  covered  and  furrounded  on  every  fide 
by  that  fluid.  And  farther,  as  the  box  was  held  faft  by  the  ftrong  fquare  iron  rod  (w;), 
which  pafled  In  a  fquare  hole  in  the  centre  of  one  of  its  ends,  (a,  fig.  4.)  while  the  round 
or  cylindrical  neck,  which  joined  the  hollow  cylinder  to  the  end  of  the  cannon,  could 
turn  round  freely  on  its  axis  in  the  round  hole  in  the  centre  of  the  other  end  of  it,  it  is 
evident  that  the  machinery  could  be  put  in  motion  without  the  leafl;  danger  of  forcing  the 
box  out  of  its  place,  throwing  the  water  out  of  it,  or  deranging  any  part  of  the  apparatus. 

Every  thing  being  ready,  I  proceeded  to  make  the  experiment  I  had  projeded  in  the  fol- 
lowing manner : 

The  hollow  cylinder  having  been  prcvioufly  cleaned  out,  and  the  infide  of  its  bore  wiped' 
with  a  clean  towel  till  it  was  quite  dry,  the  fquare  iron  bar,  with  the  blunt  fteel-borer  fixed 
to  the  end  of  it,  was  put  into  its  place  ;  the  mouth  of  the  bore  of  the  cylinder  being  clofed 
at  the  fame  time  by  means  of  the  circular  pifton,  through  the  centre  of  which  the  iron  bar 
pafled. 

This  being  done,  the  box  was  put  in  its  place  ;  and  the  joinings  of  the  iron  rod  and  of 
the  neck  of  the  cylinder,  with  the  two  ends  of  the  box,  having  been  made  water-tight  by 
means  of  collars  of  oiled  leather,  the  box  was  filled  with  cold  water,  (tIz.  at  the  tempcra- 
.ture  of  60°)  and  the  machine  was  put  in  motion. 

The  refult  of  this  beautiful  experiment  was  very  ftriking,  and  the  pleafure  it  afi"orded 
me  amply  repaid  me  for  all  the  trouble  1  had  had  in  contriving  and  managing  the  compli- 
cated machinery  ufed  in  making  it. 

The  cylinder,  revolving  at  the  rate  of  about  32  times  in  a  minute,  had  been  in  motion 
but  a  (hort  time,  when  I  perceived,  by  putting  my  hand  into  the  water  and  touching  the 
outfide  of  the  cylinder,  that  heat  had  been  generated  ;  and  it  was  not  long  before  the 
water  which  furrounded  the  cylinder  began  to  be  fcnfibly  warm. 

At  the  end  of  one  hour  I  found,  by  plunging  a  thermometer  into  the  wa,ter  in  the  box, 

(the  quantity  of  which  fluid  amounted  to  18.771b.  avoirdupois,  or  2-^  wine  gallons,)  that 

Its  temperature  had  been  raifed  no  lefs  than  47  degrees,  being  now  107"  of  Fahrenheit's 

icale> 

When 


Large  ^atithy  of  Water  made  U  boil  by  Fri^ion.  1 13 

When  30  minutes  more  had  elapfed,  or  i  hour  and  30  minutes  after  the  machinery  had 
been  put  in  motion,  the  heat  of  the  water  in  the  box  was  found  to  be  raifedto  178". 

At  2  hours '20  minutes,  it  was  at   200°;  and  at  2  hours  30  minutes  it  actuallt    . 

BOILED. 

It  would  be  difficult  to  defcribe  the  furprife  and  aftoniflimcnt  cxprefled  in  the  counte- 
nances of  the  byftanders,  on  feeing  fo  large  a  quantity  of  cold  water  heated,  and  adually 
made  to  boil,  without  any  fire. 

Though  there  was,  in  faft,  nothing  that  could  juftly  be  confidered  as  furprifing  in  this 
event,  yet  I  acknowledge,  fairly,  that  it  afforded  me  a  degree  of  childifh  pleafure,  which, 
were  I  ambitious  of  the  reputation  of  a  grave  phtlofophery  I  ought  moft  certainly  rather  to 
hide  than  difcover. 

The  quantity  of  heat  excited  and  accumulated  in  this  experiment  was  very  confiderable ; 
for,  not  only  the  water  in  the  box,  but  alfo  the  box  itfelf,  (which  weighed  is^lb.)  and 
the  hollow  metallic  cylinder,  and  that  part  of  the  iron  bar  which,  being  fituated  within  the 
cavity  of  the  box,  was  immerfed  in  the  water,  were  heated  through  150  degrees  of  Fahren- 
heit's fcale;  viz.  from  60  degrees  (which  was  the  temperature  of  the  water  and  of  the  ma- 
chinery at  the  beginning  of  the  experiment)  to  210  degrees,  the  heat  of  boiling  water 
at  Munich. 

The  total  quantity  of  heat  generated  may  be  eftimated  with  fome  confiderable  degree  of 
precifion  as  follows : 

Of  the  heat  excited  there  appears  to  have  been  adtually  accumu-         Quamity  of  ke-coM  waicr 

which,  with  the  given  (juantrty 
lated,  °f  heat,  might  have  been  heat- 

ed to  180°,  or  made  to  boil. 

In  the  water  contained  in  the  wooden  box,  1 8  ^Ib.  avoirdupois,  "    voir  upoiaweig  t. 

heated  1 50  degrees;  namely,  from  60°  to  210° F.  -  -  15.2 

In  113.131b.  of  gun  metal  (the  hollow  cylinder)  heated  150  de- 
grees ;  and,  as  the  capacity  for  heat  of  tliis  metal  is  to  that  of  wa- 
ter as  0.1 1 00  to  1. 0000,  this  quantity  of  heat  would  have  heated 
I2ilb.  of  water  the  fame  number  of  degrees.  -  -  'O.jjr 

In  36.75  cubic  inches  of  iron,  (being  that  part  of  the  iron  bar 
to  which  the  borer  was  fixed  which  entered  the  box,)  heated  150 
degrees ;  which  may  be  reckoned  equal  in  capacity  for  heat  to 
1.2 lib.  of  water.  _  _  _  .  -  i,or 

N.  B.  No  eftimate  is  here  made  of  the  heat  accumulated  in  the 
wooden  box,  nor  of  that  difperfed  during  the  experiment. 

Total  quantity  of  ice-cold  water  which,  with  the  heat  atlually 
generated  by  fridtion,  and  accumulated  in  2  hours  30  minutes,  might  ■ 

have  been  heated  1 80  degrees,  or  made  to  boil.  -  -  26.58 

From  the  knowledge  of  the  quantity  of  heat  aftualiy  produced  in  the  foregoing  experi- 
ment, and  of  the  time  in  which  it  was  generated,  we  are  enabled  to  afcertain  the  velocity  of 
its  produBioriy  and  to  determine  how  large  a  fire  mud  have  been  made,  or  how  much  fuel 

Vol.  II.— June  1798.  Q^  mu 


J»4  M'Xptrments  on  the  Heat  excited b^  Fr'iSlmi, 

mud  have  been  confumed,  in  order  that,  in  burning  equably,  it  fhould  have  produced  by  com- 
buflion  the  fame  quantity  of  heat  in  the  fame  time. 

in  one  of  Dr.  Crawford's  e-xperiments,  (fee  his  Treatifc  on  Heat,  p.  ^21)  371b.  70Z. 
troy=  1 8 1920  grains  of  water  were  heated  2, '5  degrees  of  Fahrenheit's  thermometer,  with 
the  heat  generated  in  the  combuftion  of  26  grains  of  wax.  This  gives  382032  grains  of 
water  heated  i  degree  witli  26  grains  of  wax;  or  I469,3[J  grains  of  water  heated  i  de- 
gree, or  't|?'=8i.63i  grains,  heated  1 80  degrees  with  the  heat  generated  iuthecombuf- 
tion  of  I  grain  of  wax. 

The  quantity  of  ice-cold  M-ater,  which  might  have  been  heated  180  degrees  with,  the 
heat  generated  by  friflion  in  t!ie  before-mentioned  e.xperiment,  was  found  to  be  26.5Slb. 
—  1 88060  grains  ;  and,  as  81.631  grains  of  ice-coM  water  require  the  heat  generated  in  the 
combullion  of  I  grain  of  wax  to  heat  it  1  80  degrees,  the  former  quantity  of  ice-cold  wa- 
ter, namely,  1S8060  grains,  would  require  the  combuftion  of  no  lefs  than  2303.8  grains 
(=:4-j\oz.  troy)  of  wax  to  heat  it  iSo  degrees. 

As  the  experiment  (No.  3.)  in  which  the  given  quantity  of  l>eat  was  generated  by  fric- 
tion lafted  2  hours  30  minutes  —  150  minutes  ;  it  is  necelFary,  for  the  purpofe  of  afcertain- 
ing  how  many  wax  candles  of  any  given  fize  mail  burn  together,  in  order  that,  in  the 
combuftion  of  them,  the  given  quantity  of  heat  may  be  geserated  in  the  given  time,  and 
confequently  ivith  the  fame  celerity  as  that  with  which  the  heat  was  generated  by  fri£lion  in 
the  experiment,  that  the  fize  of  the  candles  fliould  be  determined,  and  the  quantity  of  wa.\ 
confumed  in  a  given  time  by  each  candle  in  burning  equably  fhould  be  known- 

Now,  I  found  by  an  experiment  made  on  purpofe  to  finifli  thefe  computations,  that 
when  a  good  wax  candle  of  a  moderate  fize,  -|^  of  an  inch  in  diameter,  burns  with  a  clear 
flame,  juft  49  grains  of  wax  are  confumed  in  6  minutes.-  Hence  it  appears,  that  24J 
grains  of  wax  would  be  confumed  in  30  minutes  ;  and  that  to  burn  the  quantity  of  wax 
(  =  2303,8  grains)  neceflary  to  produce  the  quantity  of  heat  adually  obtained  by  friftion, 
in  the  experiment  in  quefljon,  and  in  the  given  time  (150  minutes),  nine  candles  burning 
at  once  would  not  be  fufiicient ;  for  9  multiplied  into  245  (the  number  of  grains  confumed 
by  each  candle  in  150  minutes)  amounts  to  no  more  than  2205  grains;  whereas  the  quan- 
tity of  wax  necefTary  to  be  burned,  in  order  to  procure  the  given  qnatitity  of  heat,  wa3 
found  to  be  2303.8  grains. 

From  the  refult  of  thefe  computations  it  appears,  that  the  quantity  of  heat  produced 
equably,  or  in  a  continual  flream  (if  1  may  ufe  that  expreffion),  by  the  friction  of  the  blunt' 
fteel  boreu  agarnft  the  bottom  of  the  hollow  metallic  cylinder,  in  the  experiment  under  con- 
fideration,  was  greater  than  that  produced  equably  in  the  combuftion  of  9  wax  candles, 
each  |.  of  an  inch  in  diameter,  all  burning  together,  or  at  the  fame  time,  with  clear  bright 
flames. 

As  the  machinery  ufed  in  this  experiment  could  eafily  be  carried  round  by  the  forcfe  oF 
one  horfe  (though,  to  render  the  work  lighter,  two  horres  were  actually  employed  in  do- 
ing it),  thefe  computations  fliow  farther  how  large  a  quantity  of  heat  might  be  produced  by 
proper  mechanical  contrivance,  merely  by  the  ftrength  of  a  horfe,  without  either  fire,  lighti 
combuftion,  or  chemical  decompolition ;  and,  in  a  cafe  ofneceffity,  the  heat  thus  produced 
might  be  ufed  in  cooking  viftuab.  •  • 

But 


Expenmenis  on  the  Heat  excited  by  FrlBien.  T 1-5 

But  no  circumftances  can  be  imagined  in  which  this  method  of  procuring  heat  would  not 
be  difadvantageous ;  for  more  heat  might  be  obtained  by  ufing  the  fodder  ncceflary  for  the 
fupport  of  a  horfe  as  fuel. 

As  foon  as  the  laft-mentloned  experiment  (No.  3  )  was  finilhed,  the  water  in  the  wooden 
box  was  let  off,  and  the  box  re.moved ;  and  the  borer  being  taken  out  of  the  cylinder, 
the  fcaly  metallic  powder,  which  had  been  produced  by  the  fridtion  of  the  borer  againft  the 
bottom  of  the  cylinder,  was  col!e£led,  and,  being  carefully  weighed,  was  found  to  weigh 
4145  grains,  or  about  8y  oz.  troy. 

As  this  quantity  was  produced  in  2|  hours,  this  gives  830  grains  for  the  quantity  pro- 
duced in  half  an  hour. 

In  the  firft  experiment,  which  lulled  only  half  an  hour,  the  quantity  produced  was  837 
grains. 

In  the  experiment  No.  i,  the  quantity  of  heat  generated  in  half  an  hour  was  found  to  be 
equal  to  that  which  would  be  required  to  heat  51b.  avoirdupois  of  ice-cold  water  180  de- 
grees, or  caufe  it  to  boil. 

According  to  the  refult  of  the  experiment  No.  3,  the  heat  generated  in  half  an  hour 
would  have  caufed  5.311b.  of  ice-cold  water  to  boil.  But  in  this  lad-mentioned  experiment, 
the  heat  generated  being  more  efFedlually  confined,  lefs  of  it  was  loft  ;  which  accounts  for 
the  difference  of  the  refults  of  the  two  experiments. 

It  remains  for  me  to  give  an  account  of  one  more  experiment  which  was  made  with  this 
apparatus.  1  found,  by  the  experiment  No.  i,  how  much  heat  was  generated  when  the  air 
had  free  accefs  to  the  metallic  furfaces  which  were  rubbed  together.  By  the  experiment 
No.  2,  I  found  that  the  quantities  of  heat  generated  were  not  fenfibly  diminifhed  when  the 
free  accefs  of  the  air  was  prevented ;  and,  by  the  refult  of  No.  3,  it  appeared  that  the 
generation  of  heat  was  not  prevented  or  retarded  by  keeping  the  apparatus  immerfed  in  wa- 
ter. But  as,  in  this  laft-mentioned  experiment,  the  water,  though  it  furrounded  the  hollow 
metallic  cylinder  on  every  fide,  externally,  was  not  fuftered  to  enter  the  cavity  of  the  bore 
(being  prevented  by  the  piflon),  and  confequently  did  not  come  into  conta£l  with  the  metal- 
lic furfaces  where  the  heat  was  generated  ;  to  fee  what  efFedls  would  be  produced  by  giving 
the  water  free  accefs  to  thefe  furfaces,  I  now  made  the 

Experiment  Islo,  4« 

THE  pifton  which  clofcd  the  end  of  the  bore  of  the  cylinder  being  removed,  the  blunt 
borer  and  the  cylinder  were  o-nc'e  more  put  together ;  and  the  box  being  fixed  in  its  place, 
and  filled  with  water,  the  machinery  was  again  put  in  motion. 

There  was  nothing  in  the  refult  of  this  experiment  that  renders  it  neceftary  for  me  tq 
be  very  particular  in  my  account  of  it.  Heat  was  generated  as  in  the  former  experiments, 
and  to  all  appearance  quite  as  rapidly ;  and  I  have  no  doubt  but  the  water  in  the  box 
would  have  been  brought  fo  boil,  had  the  experiment  been  continued  as  long  as  the  laft. 
Tlie  only  circumftance  iliat  furprifed  n>e  was,  to  find  how  little  difference  was  occafioned 
in  the  noife  made  by  the  borer  in  rubbing  againft  the  bottom  of  the  bore  of  the  cyHnder, 
by  filling  the  bore  with  water.  ^IThis  noife,  which  was  very  grating  to  the  ear,  and  fonie- 
times  almoft  infupportable,  was,  as  nearly  as  I  could  judge  of  it,  quite  as  loud  and  as  dif- 

,Qji  agreeable 


Il6  Experiments  on  the  Heat  excited  by  Fil^uin. 

agreeable  when  the  furfaces  rubbed  together  were  wet  with  water,  as  when  they  were  In 
conta6l  with  air. 

By  meditating  on  the  refults  of  all  thefe  experiments,  we  are  naturally  brought  to  that 
great  queftion  which  has  fo  often  been  the  fubjedt  of  fpeculation  among  philofophers, 
namely,  "What  is  heat? — Is  there  any  fuch  thing  as  an  igneous Jluid ? — Is  there  any  thing 
that  can  with  propriety  be  called  caloric  ? 

We  have  feen  that  a  very  confiderable  quantity  of  heat  may  be  excited  in  the  fri£lion  of 
two  metallic  furfaces,  and  given  off  in  a  conftant  ftream  or  flux  in  all  direHions,  without 
interruption  or  intermiffion,  and  without  any  figns  of  diminution  or  exhaultion. 

From  whence  came  the  heat  which  was  continually  given  off  in  this  manner  in  the  fore- 
going experiments  ?  Was  it  furniflied  by  the  fmall  particles  of  metal  detached  from  the 
larger  folld  mafies  on  their  being  rubbed  together  I  This,  as  we  have  already  feen,  could 
not  polTibly  have  bean  the  cafe. 

Was  it  furr.ifhed  by  the  air  ?  This  could  not  have  been  the  cafe  ;  for  in  three  of  thefe 
experiments,  the  machinery  being  kept  immerfed  in  water,  the  accefs  of  the  air  of  the  at- 
mofphere  was  completely  prevented. 

Was  it  furniflied  by  the  water  which  furrounded  the  machinery  ?  That  this  could  not 
have  been  the  cafe  is  evident ;  jf^,  becaufe  this  water  was  continually  receiving  heat  from 
the  machinery,  and  could  not  at  tlie  fame  time  be  giving  to  and  receiving  heat  from  the 
fame  body  ;  vciA,fecondly,  becaufe  there  was  no  chemical  decompofition  of  any  part  of  this 
water.  Had  any  fuch  decompofition  taken  place  (which  indeed  could  not  reafonably  have 
been  expefled),  one  of  its  compound  elaftic  fluids  (mod  probably  inflammable  air)  mud 
at  the  fame  time  have  been  fet  at  liberty,  and,  in  making  its  efcape  into  the  atmofphere, 
would  have  been  detefted  ;  but  though  I  frequently  examined  the  water  to  fee  if  any  air 
bubbles  rofe  up  through  it,  and  had  even  made  preparations  for  catching  them  in  order  to 
examine  them  if  any  fhould  appear,  I  could  perceive  none;  nor  was  there  any  fign  of  de- 
compofition of  any  kind  whatever,  or  other  chemical  procefs  going  on  in  the  water. 

Is  it  poffible  the  heat  could  have  been  fupplied  by  means  of  the  iron  bar  to  the  end  of 
which  the  blunt  fteel  borer  was  fixed  ?  or  by  the  fmall  neck  of  gun-metal  by  which  the^ 
hollow  cylinder  was  united  to  the  cannon  ?  Thefe  fuppofitions  appear  more  improbable 
even  than  either  of  thofe  before  mentioned  ;  for  heat  -was  continually  going  off  or  out  of 
the  machinery,  by  both  thefe  laft  paflTages,  during  the  whole  time  the  experiment  lafted. 

And,  in  reafoning  on  this  fubjedt,  we  muft  not  forget  to  confider  that  mod  remarkable 
circumftance,  that  the  fource  of  the  heat  generated  by  fridion  in  thefe  experiments  ap- 
peared evidently  to  be  inexhauftible. 

It  is  hardly  neceflary  to  add,  that  any  thing  which  any  infulated  body  or  fyllem  of  bo- 
dies can  continue  to  furnilh  without  limitation,  cannot  pofFibly  be  a  material  fubftance  ;  and 
it  appears  to  me  to  be  extremely  difficult,  if  not  quite  impoflible,  to  form  any  diftimSt  idea 
of  any  thing  capable  of  being  excited  and  communicated  in  the  manner  the  heat  was  ex- 
cited and  communicated  in  thefe  experiments,  except  it  be  motion. 

I  am  very  far  from  pretending  to  know  how,  or  by  what  means  or  mechanical  contriv- 
ance, that  particular  kind  of  motion  in  bodies  which  has  been  fuppofed  to  conftitute  heat 

1  » 


Experimenis  on  the  Heat  txditi  hy  FriSlim.  xf] 

is  excltCf!,  continued,  and  propagated  5  and  I  fhall  not  prefunne  to  trouble  the  Society  with 
mere  conjeftures,  particularly  on  a  fubjedl  which,  during  fo  many  thoufand  years,  the 
mofl  enlightened  philofophers  have  endeavoured  but  in  vain  to  comprehend. 

But  although  the  mechanifm  of  heat  (hould  in  fadl  be  one  of  thofe  myflerles  of  nature 
which  are  beyond  the  reach  of  human  intelligence,  this  ought  by  no  means  to  difcourage 
us,  or  even  leflen  our  ardour,  in  our  attempts  to  inveftigate  the  laws  of  its  operations.  How 
far  can  we  advance  in  any  of  the  paths  which  fcience  has  opened  to  us,  before  we  find 
ourfelves  enveloped  in  thofe  thick  mills  which  on  every  fide  bound  the  horizon  of  the  hu- 
man intelledt  ?  But  how  ample  and  how  interefting  is  the  field  that  is  given  us  to  explore! 

Nobody,  furely,  in  his  fober  fenfes  has  ever  pretended  to  underftand  the  mechanifm  of 
gravitation ;  and  yet  what  fublime  difcoveries  was  our  immortal  Newton  enabled  to  make, 
merely  by  the  inveftigation  of  the  laws  of  its  aftion  ! 

The  efFefts  produced  in  the  world  by  the  agency  of  heat  are  probably yw^  as  extenftve, 
and  quite  as  important,  as  thofe  which  are  owing  to  the  tendency  of  the  particles  of  matter 
towards  each  other  ;  and  there  is  no  doubt  but  its  operations  are  in  all  cafes  determined 
by  laws  equally  immutable. 

Before  I  finifli  this  paper  I  would  beg  leave  to  obferve,  that  although,  in  treating  the 
fubjeft  I  have  endeavoured  to  inveftigate,  I  have  made  no  mention  of  the  names  of  thofe 
who  have  gone  over  the  fame  ground  before  me,  nor  of  the  fuccefs  of  their  labours;  this 
oniiffion  has  not  been  owing  to  any  want  of  refpe£t  for  my  predeceflbrs,  but  was  merely 
to  avoid  prolixity,  and  to  be  more  at  liberty  to  purfue  without  interruption  the  natur^ 
train  of  my  own  ideas. 

Defcription  of  the  Figures.     Plate  V. 

FIG.  1.  (hows  the  cannon  ufed  in  the  foregoing  experiments,  in  the  ftate  it  was  when  it 
came  from  the  foundry. 

Fig.  2.  (hows  the  machinery  ufed  in  the  experiments  No.  i.  and  No,  2.  The  cannon  is 
feen  fixed  in  the  machine  ufed  for  boring  cannon.  W  is  a  ftrong  iron  bar  (which,  to 
fave  room  in  the  drawing,  is  reprefented  as  broken  off ) ;  which  bar  being  united  with  ma- 
chinery (not  expreiTed  in  the  figure)  that  is  carried  round  by  horfes,  caufes  the  cannon  to 
turn  round  its  axis. 

»w  is  a  ftrong  iron  bar,  to  the  end  of  which  the  blunt  borer  is  fixed,  which,  by  being 
forced  againft  the  bottom  of  the  bore  of  the  fliort  hollow  cylinder  that  remains  conne^led 
ty  a  fmall  cylindrical  neck  to  the  end  of  the  cannon,  is  ufed  in  generating  heat  by  fri£lion. 

Fig.  3.  fhows  on  an  enlarged  fcale  the  fame  hollow  cylinder  that  is  reprefented  on  a 
fmaller  fcale  in  the  foregoing  figure.  It  is  here  feen  connefted  with  the  wooden  box 
{gi  h,  /,  k)  ufed  in  the  experiments  No.  3.  and  No.  4.  when  this  hollow  cylinder  was  im- 
merfed  in  water. 

p,  which  IS  marked  by  dotted  lines,  is  the  pifton  which  clofed-  the  end  of  the  bore  of  the 
cylinder. 

«  is  the  blunt  borer  feen  fideways. 

</,  e,  is  the  fmall  hole  by  which  the  thermometer  was  introduced,  that  was  ufed  for  af- 
certaining  the  heat  of  the  cylinder.  To  fave  room  in  the  drawing,  the  cannon  is  repre- 
fented broken  oflF  near  its  muzzle ;  and  the  iron  bar,  to  which  the  blunt  borer  is  fixed,  is 
xeprefented  broken  oS^tm, 

Tig. 


J 1 8  Examtnatkn  of  the  Purity  af  Mt'Jidne/,  life. 

Fig.  4.  is  a  perfpe£tivo  riew  of  the  woaden  box,  a  fe£tion  of  which  Is  leen  in  the  fore- 
going figure.     (See  g,  A,  »,  k,  fig.  3.) 

Fig.  5.  and  6.  reprcfent  the  blunt  borer  n  joined  to  the  iron  bar  «;  to  which  it  was  faft- 
ened. 

Fig.  7.  a«d  8,  rcprefentthe  fame  borer  with  its  iron  bar,  together  with  the  pifton,  which, 
in  the  experiments  No.  2.  and  No.  3.  was  ufed  to  clofe  the  mouth  of  the  hollow  cylinder. 


IV. 

Jn  Attempt  to  dlfcover  the  Genuimnefs  and  Purity  of  Drugs  and  Medical  Preparations. 

By  I'RKDEUICK  ACCVM. 

To  Mr.  NICHOLSON. 
Sir, 

V^F  aH  the  poffible  frauds  hitherto  pra6lifcd  by  mercenary  traders,  there  is  none  more 
intimately  conne£led  with  the  welfare  of  mankind  than  the  art  of  making  or  counterfeit- 
ing drugs  and  adulterating  genuine  medicines. 

This  unprincipled  art  is  brought  to  fuch  perfeAion,  that  fpurious  articles  are  every 
where  to  be  fGUi>d  in  the  market,  made  up  with  fuch  dexterity,  that  not  only  the  mere 
merchant  and  drug  broker,  but  even  the  man  of  (kill,  is  fometimes  deceived. 

The  influence  of  this  pra£lice  has  indeed  been  obferved  by  medical  men  of  faience,, 
and  the  rulers  of  this  art  have  thought  it  their  duty  to  appoint  a  court  of  examiners 
to  invefligate  the  goodnefs  of  drugs  and  medicines  in  the  different  chemifts'  and  apothe- 
caries* fnops  in  this  metropolis. 

How  far  this  great  woric  is  accomplifhed,  or  to  what  extent  the  whole  undertaking 
docs  either  honour  and  credit  to  the  fagacity  of  thefe  learned,  liberal,  and  upright  ex- 
aminers, or  affords  juftice  to  the  public,  I  fhall  leave  to  the  determination  of  every  indi- 
vidual who  has  once  onFy  been  honoured  with  their  vifit. 

But  as  moral  duty  fliould  (timulate  every  individual  to  offer  all  the  afliftance  in  his  power 
to  fupprefs  or  check  fuch  deteftable  praftices,  I  have  ventured  to  recommend  that  me- 
thod which,  if  judicloufly  executed,  will  contribute  in  no  fmall  degree  to  the  public  good 
in  this  Tefpe£V.  If  thefe  (ketches  fhould  tend  in  any  meafure  to  put  the  unwary  on  their 
guard,  I  fhall  think  myfelf  amply  rewarded,  and  (hall  not  fail  to  extend  them  from  time  to 
♦irae,  and  lay  them  before  the  public  with  fome  confidence. 
No.  IT,  Hay-market,  FRED.  ACCI7M. 

May  ifi,  1 79!?.  ««__ 

Examination  of  Saline  Substances. 
Sulphuric  Acid. 

THE  vitriolic  acid  kept  in  our  (hops  under  the  name  of  oil  of  vitriol,  ufually  contains 
not  only  lead  in  folution,  but  likewi'fe  iron,  copper,  and  fulphate  of  potafh. 

In  order  to  difcover  thefe  admixtuires,  a  little  of  the  aci*t  mult  be  diluted  with  diftilled 
water  and  faturated  with  pure  vegetable  alkali,  as  by  this  means  tl*e  copper,  iron,  and 

S  Icai 


Examination  of  the  Purity  e/Medicities,  life,  ffpr 

lead  become  precipitated  in  the  form  of  a  more  or  lefs  dark-coloured  powder,  which  is  to 
be  feparated  by  the  filter,  and  wafljed  with  diftilled  water. 

Tb  analyle  this  precipitate,  It  is  firft  treated,  with  pure  ammoniac,  which  foon  acquires  . 

a  blue  colour  If  copper  be  prefent. The  blue  fupernatant  fluid  is  to  be  feparated,  the 

remainder  wafhed  in  diftilled  Wat«r,  and  then  diflblved  in  pure  muriatic  acid. 

In  order  to  afcertaln  the  prefence  of  lead,  the  foregoing  folution  is  mixed  with  an  equal 
quantity  of  wat-er  im,pregnated  with  fulphuratcd  hydrogen  gas;  and  if  a  dark  brown  or 
black  precipitate  enfues,  it  is  a  fure  fign  that  lead  is  prefent. 

Iron  that  may  happen  to  be  in  folution  is  exhibited  by  the  admixture  of  a  few  drops  of 
pure  prufTiate  of  potaQi  or  tin£lure  of  gall-nuts,  which  in  the  fitrft  cafe  will  produce  a  blucj. 
and  in  the  fecond  a  black  precipitate. 

Sulphate  of  potafli,  or  th«  vegetable  alkali,  united  to  fulphuric  acid  is  more  difficult  to 
difcover,  as  for  this  purpofe  a  certain  quantity  of  the  acid  is  to  be  perfeftly  faturatcd  wkL 
carbonate  of  potafh,  or  carbonate  of  ammoniac  ;  to  this  folution  a  little  tartareous  acid  is 
to  be  added,  which  by  its  fuperior  aflSnrty  will  decompofe  the  vitriolated  tartar,  and  indi- 
cate the  vegetable  alkali  under  the  form  of  tartarite  of  potafh  feparated  from  the  fluid. 
If  the  quantity  in  the  acid  be  not  very  fmall,  as  is  feldom  the  cafe,  it  may  alfo  be  dif*- 
covered  by  the  admixture  of  ftrong  ardent  fpirit  j  for  by  this  means  a  quantity  of  ful- 
phate  of  potafh,  wHl  be  feparated  in  the  form  of  a  white  powdery  precipitate. 

The  fpeci fie  gravity  of  fulphuric  acid,  according  to  our  pharmacopoeia,  fliould  be  to 
that  of  diftilled  water  as  185  to  100. 

Ir  is  void  of  fmell — perfe£Hy  colourlefs — and  boils  at  546'  of  Fahrenheit's  thermometer. 

Equal  parts  of  vitriolic  acid  and  water,  h»ftlly  mixed  together,  flwuW  produce  a.hc^''. 
nearly  equal  to  that  of  boiling  water. 

Nitrous  Acid*. 

THE  nitrous  acid  of  commerce  (or  double  aqua  fortis  aa  it  Is  commoniy  called)  always 
contains  either  fulphuric  or  muriatic  acid,  and  often  both. 

The  vitriolic  acid  may  be  difcovered  by  the  addition  of  a  few  drops  of  a  folution  of 
nitrate  of  barytes,  or  acetite  of  lead,  which  fort^  infolnble  compounds  and  fall  down.  The 
muriatic  acid  Is  manlfefted  by  thcaddition  of  a  folution  of  nitrate  o;f  fiiytfr.  In  6hi$  cafe 
muriate  of  filver  is  formed  and  precipitated. 

Its  fpecific  gravity  ftiould  be  to  that  of  diftilled  water,  as  155  to  100. 
.  If  it  is  of  an  orange  yellow  colour,  and  emits  a  vaft  quantity  of  elaftic  fluid,  known  by 
the  name  of  nitrous  gas,  which  forms  yellow  fumes  In  our  atmofphere.  Mixed  with  water, 
it  develops  a  confiderable  degree  of  heat  f . 

*vThe  infiruflion  for  preparing  nitrous  acid  according  to  our  phartracopceia  is  erroneous,  ss  the  proportion  of- 
fulphuric  acid  prcl'crilkd  is  much  too  fmall,:  it  confequentiy  leaves  a  confiderable  quantity  of  nitrate  of  potafli, 
bthind  undecompofed.    A. 

,    f  Pure  nitrous  acid  is  deprived  of  a  portion  of  nitrous  gas  by  the  application  of  heat..    It  is  then  coiourlefs, 
anJ  conftitutes  nitric  acid.     Expofure  of  nitric  acid  w  light  expels  oxygen,  and  leaves  the  acid  with  that  re..- 
.dundancy  of  azote  which  conftitutes  the  nitroUs  or  yellow  acid,  Nitric  acid  muft  therefore  he  kept  in  the  dark,, . 
•r  elfe  in  bottles  quite  full.    N. 

Muriaiie.- 


119  Eitaminailon  of  ihi  Furlt;/ of  MfdUintii  t^tt 

Muriatic  Acid*. 

COMMONLY  called  fpirit  of  fait,  always  contains  iron,  and  frequently  fulphuric  acid 
and  copper. 

The  fulphuric  acid  is  deteded  either  by  the  addition  of  barytcs,  or  acetite  of  lead,  and 
the  refults  are  the  fame  as  in  the  foregoing  experimeats. 

Copper  is  inveftigated  by  fuperfaturating  this  acid  with  pure  ammoniac,  which  in  this 
cafe  will  immediately  be  tinged  of  a  perceptible  blue. 

Iron  is  manifclled  by  previoufly  uniting  this  acid  with  carbonate  of  potafh  and  treating 
it  then  with  tinfture  of  gall-nuts,  or  pruffiate  of  potafli.  The  firft  will  produce  a  black, 
and  the  latter  a  blue  precipitate. 

The  fpecinc  gravity  of  muriatic  acid  {hould  be,  1,70  to  1,000. 

Pure  muriati  c  acid  is  totally  deftitute  of  colour. 

Acetous  Add. 

THE    concentrated  acetous  acid  commonly  met  with  contains  fulphuric  acid,  witk' 
which  it  is  either  fraudulently  adulterated,  or  with  which  it  is  impregnated  by  a  carelefs 
and  flovenly  management  during  the  procefs  for  obtaining  it. 

We  often  find  this  acid  contaminated  by  tartareous  acid,  and  not  unfrequently  by  cop- 
per or  lead.  The  prefence  of  fulphuric  acid  is  here  alfo  difcovered  by  the  addition  of 
barytes,  or  acetite  of  lead,  in  the  manner  already  mentioned. 

Tartareous  acid  is  detected  by  faturating  the  acetous  acid  with  vegetable  alkali,  in  con- 
fcquence  of  which  a  tartarite  of  potafh  becomes  feparated  in  the  form  of  a  white  powder. 

Copper  is  difcovered  by  faturating  the  acid  with  carbonate  of  ammoniac,  and  lead  be- 
comes manifefted  by  mixing  it  with  water  impregnated  with  fulphurated  hydrogenous 
gas.     In  the  firft  cafe  a  blue,  and  in  the  fecond  a  black  precipitate  will  be  formed. 

The  fpecific  gravity  of  the  moft  concentrated  acetous  acid  fhould  be  to  that  of  water 
as  1,050  to  1,000.     It  is  colourlefs,  and  of  a  penetrating  fmell. 

Dljlllled  Vinegar. 

VINEGAR,  if  not  diftilled  In  glafs  veffels,  but  in  a  ftlll  with  a  pewter  head,  always  con- 
tains lead  in  folution. 

To  difcovcr  this,  equal  quantities  of  vinegar,  and  water  impregnated  with  fulphurated 
hydrogenous  gas,  are  mixed  together,  which  mixture,  if  the  vinegar  is  free  from  lead,  will 
remain  unaltered  ;  whereas,  on  the  contrary,  the  fmalleft  quantity  of  this  metal  will  pro- 
duce a  black  precipitate. 

We  frequently  meet  with  diftilled  vinegar  adulterated  with  fulphureous  acid,  the  pre- 
fence of  which  is  detedted  by  means  of  nitrate  of  barytes,  or  acetite  of  lead,  as  mentioned 
before. 

•  The  proportion  of  fulphuric  acid  prefcribed  by  our  royal  college  of  phyficians  for  obtaining  this  acid  is  much 
too  great,  as  18  or  to  ounces  are  quite  fufficient  for  a  total  decompofition  of  the  quantity  of  muriate  of  pouih 
ordered. 

The 


£xamiitation  of  the  Purily  of  Medicines,  iife,  -J<tt 

The  bed  diftilled  vinegar  has  a  pleafant  tafte  and  fragrant  fmell,  is  perfeftly  colourlefs, 
and  twelve  parts  of  it  require  one  of  dry  vegetable  alkali  to  neutralife  it. 

Boracic  Acid. 

ON  account  of  the  hlgli  price  which  this  acid  bears,  we  often  meet  with  it  intcntiohaHy 
adulterated  with  Venetian  talc,  afbeft,  &c. 

Genuine  boracic  acid  is  foluble  in  five  times  its  quantity  of  boiling  ardent  fpirit,  and 
the  folution  when  fet  on  fire  burns  with  a  green  flame.  In  water  it  diflblves  tardily  j 
when  fubmitted  to  the  blow-pipe  it  fluxes  to  a  perfefl  tranfparent  glafs  if  genuine  ;  it  vi- 
trifies earth  and  ftones.  If  it  be  added  in  fmall  quantities  to  tartarite  of  potafli,  it  tranf- 
forms  it  into  a  very  foluble  fait.  The  bed  boracic  acid  is  exhibited  in  fmall  hexangular 
fcaly  cryftals,  of  a  (hining  filvery  white  colour.  It  difcovers  only  a  flight  acid  tafte,  and 
does  not  deliquefce  in  the  air. 

Its  fpecific  gravity  is  1,480. 

Tartareous  Acid. 

TARTAREOUS  acid  may  very  eafily  be  contaminated  with  fulphuric  acid,  either  frau- 
dulently or  in  confequence  of  a  faulty  preparation. 

The  admixture  of  fulphuric  acid  is  foon  difcovered,  if  a  fmajl  quantity  of  the  tartareous 
acid  be  diflblved  in  diftilled  water,  and  a  few  drops  of  a  folution  of  acetite  of  lead  arc 
added  to  it :  by  this  means  a  white  precipitate  is  afforded,  which,  by  the  addition  of  a  few 
drops  of  pure  nitric  acid,  will  be  entirely  rediflblved  if  no  fulphuric  acid  is  prefenfc.  The 
prefence  of  tliis  acid  is  ftill  more  readily  manlfefted  by  adding  to  the  tartareous  acid  dif- 
folved  in  diftilled  water  a  few  drops  of  a  folution  of  nitrate  of  barytes,  in  confequence  of 
which  fulphate  of  barytes  will  immediately  be  generated. 

Pure  cryftallized  tartareous  acid  does  not  change  by  expofure.to  air;  It  is  very  foluble 
in  water,  and  poflefles  a  grateful  acid  tafte. 

Acid  of  Anther. 

WE  find  this  acid  wonderfully  adulterated  fometimes  with  fulphuric  acid  and  all  its 
combinations,  fometimes  with  tartareous  acid,  and  now  and  then  with  muriate  of  am- 
moniac. 

The  fulphuric  acid  is  difcovered  by  means  of  nitrate  of  barytes,  or  acetite  of  lead. 

The  tartareous  acid  is  difcovered  by  means  of  vegetable  alkah  j  for,  if  this  acid  be  pre- 
fent,  a  quantity  of  tartarite  of  potafli  will  be  fprmed. 

Muriate  of  ammoniac  is  difcovered  with  refpe6l  to  one  of  its  component  parts  (the  mu- 
riatic acid),  by  the  folution  of  nitrate  of  filver;  and  with  refpeft  to  the  other  (the  am- 
moniac) by  adding  to  the  aqueous  folution  of  this  fait  a  little  vegetable  alkali,  and,  after 
heating  the  mixture,  holding  over  it  a  ftopper  moiftened  with  acetoijis  acid>  white  fumes 
will  be  formed,  which  indicate  that  ammoniac  is  prefent.        ,.,  ^       : 

Pure  acid  of  amber  is  a  cryftalline  white  fait,  of  an  acid  tafte,  foluble  in  twenty-four 
times  its  weight  of  cold  water,  but  in  eight  when  boiling  hot,  and  is  volatilized  on  an  ig- 
nited iron,  leaving  neither  allies  nor  any  other  refidue  behind. 

Vol.  II.— June  1798.  R  Acid 


tti  Injifutntni  for  exhibiting  Jupiter  and  hu  Motnti 

Jcid  ofBenzoiUf 

WHICH  is  commonly  known  by  the  name  of  flowers  of  benjamin,  is  not  liable  to  br 
eafily  adulterated. 

•  The  bed  flowers  of  benjamin  are  brilliant  white,  pofl^efs  a  peculiarly  grateful  finell,  are 
totally  foluble  in  boiling  water  and  ardent  fpirit,  and  leave  no  refidue  or  aflies  w^en  laid 
upon  a  red-hot  iron,  or  on  ignited  coals. 


A  Model  propopd  for  the  ConJlruETion  ofaSatdlitian,  or  Injlrument  for  explaining  the  Phtnomenm 
of  Jupiter  and  his  Satellites,  with  an  Account  of  its  Ufe.  By  the  Rev.  W.  PEARSON,  of 
Lincoln  *. 

OINCE  the  dodlrine  of  brlghtnefs  has  been  particularly  attended  to  by  Mr.  Herfchell  ia 
liis  obfervations  of  the  heavenly  bodies,  this  celebrated  aflronomer  has  been  able,  by  means 
of  {he  excellence  of  his  telefcopes,  to  announce  to  the  world,  what  his  predeceflbrs  could 
only  conje£lure,  not  only  that  the  fatcllites  of  Jupiter  have  each  a  rotatory  motion  on  their 
axes,  but  alfo  the  exa61  time  of  each  rotation.  In  Part  II.  of  the  Philofophical  Tranfac- 
tions  of  the  Royal  Society  of  the  lad  year  [1797],  is  an  article  in  which  Mr.  Herfchell  has 
proved,  I  think,  in  a  fatisfa£lory  manner,  that  each  of  thefe  four  fatellites  has,  like  our 
moon,  jufl;  one  rotation  in  every  periodical  revolution  round  its  primary,  viz.  The  firft  or 
neareft,  in  i  day  8  hours  and  26x0-  minutes ;.  the  fecond,  in  3  days  13  [by  a  typographical 
error  made  18]  hours  and  l^^a  minutes  ;  the  third,  in  7  days  3  hours  and  59^5  minutes  ;. 

and  the  fourth,  in  16  days  18  hours  and  5-rV  minutes. This  difcovery  of  a  rotation  in 

each  revolution  renders  die  analogy  fo  ftriking  between  the  Jovian,  as  a  detached  part  of 
the  folar  fyftem,  and  that  of  our  own  earth  and  moon,  that  we  can  hardly  any  longer  doubt 
whether  or  not  Jupiter  be  inhabited.  Such  a  confideration,  in  my  opinion,  renders  the 
Jovian  portion  of  the  folar  fyftem  a  fubjedl  which  merits  more  particular  attention  than  is 
ufiially  allotted  to  it  in  Ie£lures  upon  aftronomy ;  and  on  this  account  I  have  contrived  the 
model  of  an  inflirument  of  a  fimple  conftruflion  for  the  purpofe  of  explaining  the  different 
phenomena  thereof,  which,  for  want  of  a  more  appropriate  name,  I  fhall  take  the  liberty 
of  calling  a  fatellitian.  Other  inflruments  to  anfwcr  the  fame  purpofe  may  have  been 
conftrucled  and  ufed  •,  but  as  I  have  no  kttowledge  of  any,  except  that  Mr.  Rowley's  grand 
ortery  is  faid  to  reprefent  Jupiter's  fatellites  moving  by  wheel-work  f,  I  feel  myfelf  war- 
ranted in  prefenting  to  the  public  a  plan  and  defcription'of  the  conftituent  parts  of  this 
detached  inftrument,  and  of  the  method  of  ufing  it,  in  hopes  that  it  may  prove  not  unao- 
ceptable  to  the  cultivators  of  fcience,  or  at  leaft  that  it  may  fuggeft  to  fome  more  inge- 
nious artift  the  means  of  making  a  more  eligible  one, 


•  Gommunicated  by  the  author. 

■^  A  macfiine  for  this  purpofe  is  alfo  defcrlbed  in  Harris's  Lexicon  Technicum.    N. 


la 


liijlrumentfor  exhihittng  Jiipitey  and  his  Aloons.  tjj 

In  figure  l  of  plate  VI.  is  exhibited  a  lateral  view  of  the  wheels  of  this  hiftrument, 
which  are  calculated  for  producing  the  mean  motions  of  the  four  fatellites,  and  contained 
in  the  brafs  box  ABCD,  8-^'^  inches  long  within,  4  broad,  and  i^^  deep.  Figure  2,  EF, 
reprefcnts  the  cover  of  this  box,  on  which  the  different  faces  for  the  hour,  week,  and 
month-hands  are  graduated  and  filvered  :  the  fmall  concentric  wheels  marked  8,  18,  27, 
and  39  in  fig.  i«  are  all  fixed  on  the  fame  revolving  axle,  placed  on  the  point  H,  which 
carries  the  hour-hand  on  its  upper  end  once  round  in  24  hours  ;  but  the  larger  correfpond- 
ing  wheels,  134,  129,  96,  and  69,  are  fixed  on  the  ends  of  as  many  feparate  tubes  or  hol- 
low axles  of  brafs,  which  juft  turn  eafily  round  within  one  another,  and  are  fupported  by  a 
fhoulder  in  the  perpendicular  fixed  ftem  that  holds  Jupiter  over  the  point  S  ;  the  inner- 
moll  being  the  longed,  and  the  next  to  the  innermoft  the  next  in  length,  as  in  a  common 
planetarium  :  thefe  tubes  have  each  a  broad  ring  of  a  proper  diameter  to  Aide  a  little  way 
upon  their  upper  ends,  to  which  are  riveted  the  crooked  arms  which  fupport  the  fatellites ; 
and  the  rings  are  turned  round  the  tubes  in  the  adjuftment  of  the  fatellites  to  their  rela- 
tive fituations ;  the  tubes  alfo  have  flioulders  each  for  the  fupport  of  its  next  fuperior 
wheel,  and  are  kept  in  their  places  by  the  lower  edges  of  the  rings. 

All  the  parts  of  the  fatcllitian  are  laid  down  in  the  plate  in  their  proper  proportions 
and  full  fize,  according  to  the  following  table,  from  which  an  artift  of  but  little  ingenuity 
may  eafily  conftruft  it,  provided  he  is  furniflied  with,  or  has  accefs  to,  a  cutting  engine  for 
making  the  wheels,  the  plate  of  which  is  properly  divided  for  the  required  numbers.  An 
eafy  method  for  dividing  a  plate  is  laid  down  in  Mr.  Fergufon's  "  Seleft  Exercifes,"  in 
fubftance  thus  :  As  all  the  teeth  in  any  wheel  are  to  360**,  fo  are  any  odd  number  of  teeth, 
to  the  number  of  degrees  to  be  marked  out,  and  divided  into  that  odd  number;  after  wliich 
the  remaining  even  number  may  be  very  eafily  divided  by  continued  halves. 


Table  of  Dimenfions  *. 


Wheels 

Diam.  in  Inches  from 

Diftance   of    the   Satellites  from 

. 

the  Pitch  Line. 

Jupiter  in  Diameters  of  him. 

*34 

2,8 

I.  Satellite  2-5-  diameters. 

129 

2,6 

2.  do.   —  41-  do. 

96 

2.3 

3.  do.   —   7^  do. 

69 
8 

1.9 

4.  do.    —  I2y  do. 

0,2 

18 

0,4 

FromS  to  H  i finches. 

27 

0.7 

From  H  to  W  0,68  do. 

39 

i.i 

From  W  toP  2,125  do. 

56 

1 .2 

7 

o,3S 

73 

3.9 

»  The  wheels  in  the  table  are  proportioned  thus : — As  the  fum  of  the  teeth  in  any  two  corf  efponding  wheel* 
is  to  the  diftance  between  their  centres,  or  fum  of  their  femidiameters,  fo  is  the  number  of  teeth  in  each, 
taken  feparately,  to  its  femidiameter  :  an  allowance  being  afterwards  made  for  the  driving  wheel  being  fome- 
what  larger  in  this  proportion  than  the  driven  one,  to  make  them  work  more  eafily.— —-W.  P. 

R2  ThougU 


nf  Injlrument  fir  exhibiting  Jupiter  and  his  Moons. 

Though  tKc  dimenfions  of  the  wheelwork  here  given  are  convenient  for  the  conftru^lion- 
of  the  fatellitiau,  yet  the  box  may  be  in  the  form  of  a  fquare,  an  oftagon,  or  a  circle  ; 
though  a  parallelogram  feems  to  be  the  moft  portable;  but  of  whatever  fliape,  there  mud 
bfe  a  contrivance  for  cramping  or  otherwife  filing  it  to  a  table  when  ufed. — The  fize  of  tlie 
bail,  which  reprefents  Jupiter  in  the  plate,  is  proportioned  to  the  length  of  the  arms  which 
carry  the  fatellites,  and  ought  not  to  be  larger  ;  for  an  increafed  length  of  the  arms  would 
not  admit  the  fcreen  to  approach  near  enough  to  prevent  the  divergence  of  the  fliadows.— 
The  balls  which  reprefent  the  fatcllites  fhould,  however,  be  as  diminutive  as  poflible,  fo 
that  they  give  adiflin£l  fliadow  by  candlelight.  According  to  Mr.  Herfchell's  obfervations, 
the  third  is  the  largeft,  the  firft  and  fourth  nearly  equal,  and  the  fecond  the  fmalleft  :  their 
colours  are,  in  his  own  words,  as  follows  :  the  firft  is  "  white,  more  fo  fometimes  than 
others-,"  the  fecond  "  white,  blueifli,  and  afh-coloured  ;"  the  third  "  white,  differently  in 
different  fituationsj"  and  the  fourth  "  dufky,  dingey  inclining  to  orange,  reddifli,  and  ruddy 
at  different  times." 

A  motion  is  communicated  to  the  machinery  by  means  of  a  fingle  endlefs  fcrcw,  on  an 
horizontal  axle,  lying  acrofs  the  box  at  the  fmall  black  circle  near  73,  and  working  with  the 
teeth  of  this  wheel :  a  handle  is  put  upon  the  projeding  end  of  this  axle,  which  cannot  ap- 
pear in  the  plate,  at  fuch  a  dlftance  from  the  fide  of  the  box,  as  may  prevent  the  hand  of 
the  perfon  who  turns  it  from  touching  any  of  the  fmall  balls,  or  intercepting  the  view  of  a 
fmall  company  of  fpe£l:ators. 

As  appendages  to  the  fatellitian,  a  fmall  Aiding  fcreen  of  thin  paper  and  an  appropriate 
candleftick  are  necefTary. — The  mode  of  adjufting  the  fcreen  is  optional,  and  therefore  re- 
quires no  defcription. — The  bafe  of  the  candleftick,  of  which  a  fketchis  given  in  miniature 
^'  fig-  3>  confifts  of  a  circular  plate  of  brafs  4  inches  diameter,  divided  into  the  12  figns, 
and  graduated  in  concentric  circles  near  the  extremity  :  in  the  centre  of  this  ftands  a  fliort 
perpendicular  flem  of  a  cylindrical  form,  which  fcrews  into  a  folid  piece  foldered  on  the 
furface  of  the  plate,  and  has  a  focket  proper  for  containing  a  candle  or  lamp  at  the  upper 
end  :  on  the  low  end  of  this  ftem  turns  a  broad  ring,  into  which  an  arm  is  riveted 
3  inches  long,  which  has  a  fimilar  focket  on  its  upper  end,  and  oppofite  thereto  a  hand  alfo 
riveted,  which  points  to  the  giraduated  ecliptic  oppofite  to  the  part  on  which  the  arm  refts^ 
at  all  times. 

In  order  to  eftimate  the  accuracy  of  the  mean  motions  of  the  little  balls  in  the  fatellitian, 
we  muft  confider  each  pair  of  correfponding  wheels  as  an  improper  fra£tion  of  a  day ; 
thus  11  of  24  hours  is  equal  to  i  d.  i8  h.  27  min.  41  fee. ;  |^  is  equal  to  3  d.  I3h.  aomin.j 
^^  is  equal  to  7  d.  4  h,  o  min. ;  and  '-j-*  equal  to  16  A.  1 8  h.  o  min.  ;  whence  it  appears 
that  the  error  in  one  day's  mean  motion  of  the  firft  fatellite  is  not  quite  +  37'';  of  the 
fecond  fomewhat  more  than   +   3.7'';   of  the  third  not  quite  +  3''4: »  *««!  of  the  fourth 

about— 18". The  firft  and  fecond  of  thefe  errors  will  amount  to  one  hour's  motion: 

of  each  fatellite  in  about  97!  days'  ufe  with  one  redification  ;  but  the  third  and  fourth  will: 
not  be  perceptible  by  the  eye  in  fcveral  years,  by  reafon  of  the  flownefs  of  the  fatellites'' 
motions,  as  well  as  fmallnefs  of  their  daily  errors.    With  regard  to  the  calculation  of  the. 
other  wheels,  the  fradion  '/  is  equal  to  7  days  for  the  week-hand  ;  and  the  compound 
one  'y   ^  V  is  equal  to  73,5  but  the  foiral  face  on  the  cover  has  five  lines  divided  into 

365  equal 


hijirument  far  e:<htbit'wg  Jupiter  and  his  Moons.  tij 

36J  equal  parts,  therefore  five  revolutions  of  the  month-hand,  viz.  5  X  73,  will  complete 
the  year.  The  365  days  in  the  fpiral  are  divided  into  calendar  months,  the  initials  of  each 
of  which  ftand  immediately  over  the  beginning  of  the  firft  day  of  each  ;  fo  that  when  the 
inftrument  is  redified  for  the  month,  day,  and  hour  at  any  particular  time,  the  different 
hands  will  preferve  tlieir  refpcftive  fituations  to  the  end  of  the  year,  and  fo  on  from  year 
to  year,  provided  the  month-hand  be  put  back  one  day  in  the  fpiral  at  the  latter  end  of 
February  in  every  leap  year.  This  putting  back,  however,  will  not  in  the  lead  affeft  the 
motions  of  the  fateilites;  for  the  hands,  being  put  upon  the  circular  ends  of  the  axles,  will 
turn  in  adjuftment  without  giving  motion  to  the  wheels. 

As  the  error  in  the  firft  and  fecond  fateilites  will  amount  in  one  year  to  about  three 
hours  and  forty-four  minutes  motion  of  each,  they  muft  alfo  after  that  fpace  be  put  to 
their  right  places  again,  which  is  very  eafily  done  thus  :  Turn  the  handle  in  a  retrograde 
direction  till  all  the  fateilites  have  come  back  4h.  44;min.  then  hold  the  firft  and  fecond 
in  that  particular  pofition  while  the  handle  is  again  turned  to  its  original  fituation,  and 
tlien  let  them  be  at  liberty. — If  this  is  done  at  a  quarter  of  a  year  after  reftification,  the 
error  will  be  fomewhat  lefs  than  an  hour,  and  it  may  render  a  new  re£lification  by  the 
nautical  almanac,  as  will  be  defcribed  hereafter,  needlefs. 

If  at  any  time  the  letter  pointed  to  in  the  week  circle,  and'  the  correfponding  day  of  the 
month  in  the  fpiral,  in  the  firft,  fecond,  third,  fourth,  or  fifth  line,  as  the  cafe  may  be,  be 
both  attentively  obferved,  it  will  appear  by  infpedlion  for  what  particular  time  the  fatel- 
litian  ftands  redificd  in  a  given  year  after  it  has  been  out  of  ufe  ;  for,  as  the  month-hand 
lies  over  the  five  lines,  that  particular  line  is  the  proper  one,  the  numerical  point  of  which 
anfwers  to  the  initial  of  the  day  to  which  the  week-hand  points  :  for  example,  in  the  plate 
the  redification  of  the  hands  is  for  noon  of  Wednefday  June  14,  1797.  Without  a  regard- 
to  fuch  an  infpeclion,  a  new  re£tification  would  become  necelTary  every  time  the  inftru- 
toent  was  to  be  ufed,  and  in  fome  cafes  probably  when  the  means  of  redlification  might 
not  be  immediately  attainable. 

If  the  orbits  of  the  fateilites  were  not  neceflarlly  too  large  in  the  fatellitian  to  be 
proportional  to  thofe  of  the  earth  and  Jupiter,  when  the  latter  is  placed  at  fuch  a  diftance 
from  them  as  that  a  candle  in  its  place  may  produce  a  diftin£t  (hadow  of  each,  5-r\  times 
the  diftance  between  the  two  fockets,  viz.  15-;%  inches,  would  be  the  proper  diftance  of  the 
central  candle  from  Jupiter,  in  which  pofition  the  angle  at  Jupiter  in  the  fatellitian  fubtend- 
cd  by  the  diftance  between  the  fockets,  viz.  3  inches,  would  be  equal  to  the  parallax  of  the 
earth's  annual  orbit  feen  from  Jupiter  j  but  as  the  exa6l  proportions  of  all  their  orbits 
cannot  be  preferved,  a  mechanical  adjuftment  becomes  requifite  to  preferve  the  due  ar- 
rangement of  the  Ihadows  upon  the  fcreen. 

The  re£lification  ought  always  to  be  very  minutely  attended  to,  and  is  thus  effe£led  : 
Fix  the  fatellitian  firmly  on  a  table,  and,  fetting  the  centre  of  the  candleftick  jud  four  feel 
from  Jupiter,  place  a  fteady  burning  candle,  or  rather  a  lamp,  in  the  central  focket,  upon 
the  fame  level  with  Jupiter  in  the  inftrument,  and  a  fimilar  one  in  the  focket  fupported  by 
the  arm  at  the  fame  height ;  by  this  means  two  fliadows  of  Jupiter  will  fall  upon  the 
fcreen  when  placed  behind  the  fatellitian  :  Aide  the  fcreen  as  near  Jupiter  as  a  revolution 
of  the  longeft  arm  will  fuffer  it  to  approach,  which  will  be  cpwaids  of  2-|  inches  j  and  if 

the 


126  liijlruinent  for  exhibiting  Jupiter  atid  his  Afoons. 

•the  central  candle  and  Jupiter  form  a  right  angle  at  the  other  candle,  the  two  fliadofls 
•will  cover  one  another  •juft  fo  much  as  is  reprefented  i\\  fig.  4.  or  fig.  6.  -,  but  if  this  is  not 
cxaftly  the  cafe,  the  candleftick  muft  be  brought  nearer,  or  removed  farther,  till  this  ap- 
pearance is  produced  ;  and  then  the  fcreen  mufl  be  fecured  in  its  place,  and  the  candleftick 
be  fufl'crcd  'to  remain.  In  the  nest  place,  -with  a  pair  of  bow-compafles  defcribe  a  circle 
coincident  with  that  fhadow  which  is  occafioned  by  the  central  candle;  and  within  that, 
three  other  concentric  circles,  the  largeft  of  the  three  to  touch  the  edge  of  the  other  fha- 
dow when  the  arm  remains  unmoved  ;  the  next  to  touch  the  fame  when  the  arm  is  46' 
from  conjundtiou  with  Jupiter  and  the  central  candle  ;  and  the  fmalleft  to  touch  the  fame 
when  the  arm  is  24"  from  a  fimilar  fituation. 

Here  then  the  central  candle  will  reprefent  the  fun  ;  the  outermoft  circle  In  fig.  4.  or  5. 
tlie  diametrical  fe£lion  of  the  fun's  ftiadow  at  the  orbit  of  the  firfl  fatellite  ;  the  fecond 
circle  is  fuppofed  to  reprefent  the  appearance  of  the  fame  at  the  orbit  of  the  fecond  ;  the 
third,  the  appearance  at  that  of  the  third  ;  and  the  fmall  one,  the  appearance  at  that  of 
the  fourth,  as  viewed  in  perfpe£tive  from  the  earth  ;  whilft  the  candle  carried  by  the  arm 
will  be  the  reprefentative  of  the  earth.  Remove  now  the  central  candle,  and  Jupiter's 
remaining  fliadow  will  be  his  fituation  as  viewed  from  the  earth,  coinciding  with  his  real 
fhadow,  reprefented  by  the  concentric  circles,  as  far  as  the  orbit  of  the  fecond  fatellite,  and 
then  difunltin^. 

Hitherto  the  fatellltes  themfelves  have  been  difregarded,  and  mufl;  next  be  placed  in  their 
proper  fituations  by  the  help  of  a  *  nautical  almanac,  thus :  Look  for  the  day,  for  which 
the  fateUitian  is  to  be  rectified,  among  the  configurations  given  in  the  lad  page  of  every 
month,  and  the  relative  apparent  fituations  of  all  the  fatellites,  at  the  hour  fpecified  at  the 
top,  will  be  found  to  the  right  and  left  of  the  central  cypher  which  reprefcnts  Jupiter. 
When  the  numerical  figure  ftands  between  the  reprefentative  point  of  any  fatellite  and  Ju- 
piter, the  fatellite  is  approaching  him ;  but  when  the  point  is  put  the  nearer,  It  is  reced- 
ing from  him :  alfo,  when  a  fatellite  is  approaching  on  the  right  hand  of  Jupiter,  or  re- 
ceding on  the  left,  it  is  in  its  fuperlor  femicircle,  and  is  placed  above  the  centre  of  the  cy- 
pher -,  but  when  receding  on  the  right,  or  approaching  on  the  left,  it  is  in  its  inferior  one, 
and  ftands  higher  than  the  centre.     The  relative  fituations  and  diredlon  of  motion  of  each 
fatellite  being  obferved,  put  them  all  to  their  places  as  near  as  the  eye  can  guefs  by  the 
lliadows  compared  to  the  points  in  the  almanac  ;  then,  having  prevloufly  marked  the  great- 
eft  elongation  of  the  fourth  with  little  points  on  the  fcreen,  by  means  of  a  fe£lor  or  dia- 
gram of  fimilar  triangles,  make  the  diftatice  of  each  fhadow,  from  Jupiter's  centre  on  the 
fcreen,  bear  the  fame  proportion  to  the  diftance  of  each  point  from  the  centre  of  the 
cypher  in  the  almanac,  that  the  greateft  elongation  of  the  fourth  on  the  former  bears  to 
the  greateft  elongation  of  the  fame  in  the  latter:  this  will  be  attended  with  no  difficulty.— 
The  re£tification  for  the  true  places  of  mean  motion  will  however  be  the  more  accurate  the 

•  The  reftification  may  be  made  mod  accurately  by  calculating  the  time  of  a  conjunftion  of  each  fatellite, 
tneanot  apparent,  as  may  be  required,  by  the  help  of  Wargentin's  Tables,  in  any  given  month:  but  every 
jcadcr  cannot  be  fuppofed  to  have  fuch  Tables ;  and  therefore  the  configurations  are  here  fubftituted  as  af- 
■fwdjng  a  more  general,  as  well  as  fwriiliar  method.— —W.  P. 

o  fmaller 


Bijnmetii  for  exhibiting  Jupiter  and  his  Moont.  127 

fonaner  the  grand  equation  of  the  fatellites,  which  depends  upon  Jupiter's  anomaly  at  the 
time  of  redtification. 

The  lad  moft  favourable  time  was  on  0£tober  i  r,  1794,  and  the  next  leaft  favourable 
will  be  o'l  July  5,  j8oo:  the  former  will  recur  on  Augufl  21,  i8c6,  and  the  latter  on 
May  17,  1 812;  and  two  of  each  will  follow  at  nearly  fix  years  diftance  from  each  other 
in  each  revolution  of  Jupiter  afterwards. 

If  the  diameters  of  the  cyphers  in  the  nautical  almanac,  which  are  too  fmall,  were  fo  fau 
augmented  as  to  bear  an  *  exa£t  proportion  to  the  greateft  elongations  of  the  fatellites  there 
exhibited,  which  appears  to  be  not  the  cafe,  their  apparent  places,  meafured  by  thofe  dia- 
meters,, might  be  eafily  afcertained  without  further  trouble  on  any  given  day,  as  well  as 
their  true  places  of  mean  motion  at  the  fultable  times  above  fpecified. 

The  configuration  fig.  7.  is  for  half  paft  fix  P.  M.  on  Odlober  1 1, 1 794,  where  it  appears, 
from  what  has  been  already  remarked,  th^t  the  firft  fatellite  is  approaching  Jupiter  in  its 
fuperior  femicircle  near  its  greateft  weftern  elongation ;  the  fecond  receding  in  itsinferior  }, 
and  the  third  and  fourth  receding  each  in  its  fuperior ;  tha  third  being  near  its  greateft 
caftern  elongation.  The  correfponding  places  of  the  fliadows  on  the  fcrecn,  when  the  fa— 
tellitian  is  re£tified  for  this  time,  will  appear  as  in,  fig.  8. 

The  fliadows  may  be  made  to  fall  a  little  higher  in  their  inferior  femicircle  than  in  their.- 
fuperior,  by  giving  the  inftrument  a  fmall,  recllnation  with  a  thin  wedge  placed  under  the 
end  next  the  candle,  or  by  an  adjufting  fcrew  preffiiig  againft  the  table,^  which  efFedl  is 
greateft  with  the  fourth. 

In  this  reprefentation  the  fatellites  are  very  nearly  in  their  true  places  of  mean  motion, 
as  well  as  in  their  apparent  places  :  therefore,  if  the  fatellitian  be  rectified  for  Saturday 
October  11,  1794>  at  half  paft  fix  in  the  evening,,  by  this  latter  configuration,  and  the 
handle  be  turned  till  the  month-hand  comes  to  the  end  of  February  1796,  before  it  be  put 
back  a  day,  and  thence  forward  to  the  prefent  time  (1798),  provided  the  firft  and  fecond 
arms  be  alfo  adjufted  for  their  errors  in  motion,  as  already  direcled,  the  redification  will. 
be  more  accurate,  for  mean,  motion  at  prefent  than  if  made  by  the.  almanac  at  a!ny  other 
time. 

From'  1794  to  1800  the  difference  between  mean  and  apparent  motion  of  the  fatellites, 
rejefting  the  fmaller  equations,  is  increafing  ;  and  from  1800,. when  it  will  be  a  maximum, 
to  1 806,  it  will  decreafe,  the  apparent  being  fafter  than  the  mean,  according  to  the  year 
f^r  which  the  fatellitian  is  to  be  ufed  :  from  1806  to  1812  it  will- again  increafe,  after 
which  time  a  decreafe  will  commence ;  and,  in  a  little  lefs  than  every  fix  years,  the 
increafe  and  decreafe  will  continue  to  be  alternate  for  the  time  to  follow.. 

Laftly  :  Put  the  index  of  the  candleftick  to  the  fun's  place  in  the  ecliptic,  and  the  hello* 
centric  longitude  of  Jupiter  taken  from  a  nautical  almanac  or  White's  Ephemeris,  imme-- 
diately  between  the  central  ftem  and  Jupiter  in  the  machine,  by  means  of  a  thread  ftretched 
and  tied  to  both,  which  will  ferve  as  an  index,, as  well  as  a  guide  for  the  diftance  of  the 

•  The  diameter  of  Jupiter  is  reprefcnted  in  the  oppofite  extreme,  in  the  Encyclopaedia  Britaonica,  Ijoth  in 
Sg.  1 8.  plate  6z.  and  in  fig.  177.  plate  79.  though  it  is  faid,  in  vol.  ii.  part  2.  p.  577.  that  "  the.  orbits  of 
Jupiter's  moons  are  drawn  in  true  proportion  to  his  diameter''  in  tlie  latter  diagram,  and  are. evidently  in. 
tended  to  be  fuch  in  the  f«rmer,— -W,  P, 

candJeftickj^ 


I  at  Jnjruvient  far  exhibiting  Jupiter  and  his  Maons. 

candlfdick ;  ntjd  in  this  fituatiou  the  rcprefentitlves  .of  the  Sun,  Earth,  and  JupUer,  %% 
alfo  of  t!ie  fatellites,  will  all  be  in  tlieir  relative  fituations  for  exhibiting  the,  general  phenor 
jnena  of  the  Jovian  as  a  detached  fyftem. 

:.'fiut  before  I  give  a  particular  defcription  of  thefe  phenomena  as  they  will  be  exhibited 
by  the  fatellitian,  the  reader  will  perhaps  form  a  more  accurate  conception  of  the  extent 
of  its  application,  if  a  fummary  account  be  firft  given  of  thofe  minute  irregularities  in  thcs 
motioHS  of  the  fatellites,  which  no  Cmple  machinery  can  be  fuppofed  to  reprefent. 

The  fatellites  of  Jupiter  were  difcovered  by  Galileo  in  January  1610,  and  called  Medi- 
ceanjlarsy  in  honour  of  Cofmo  Medici  great  duke  of  Tufcany.  This  aftronomer  conti- 
nued his  obfervations  upon  them  for  27  years,  till  unfortunately  the  lofs  of  fight  fruftrated 
the  fruit  of  his  continued  labours.  In  1663  Borelli  publiflied  a  theory  of  the  Medicean 
Stars,  but  had  not  acquired  data  fufficient  for  afcertaining  the  exadl  quantities  and  qualities 

of  their  motions After  him  Caffini,  in  the  year  1668,  favoured  the  world  with  "  Tables 

of  the  Motions  of  Jupiter's  Satellites,"  which  were  improved  and  edited  by  him  again  in 
1693.  Thefe  Tables  have  fince  that  time  been  rendered  ftill  more  accurate  by  Meflrs. 
Hadley,  Pound,  Bradley,  &c.  as  alfo  by  the  French  aftronomers,  and  laflly  by  Wargentin 
the  Swedifh  aflronomer,  whofe  beil  Tables  are  now  ufed  in  calculating  the  immerfions 
and  emerfions  given  in  the  nautical  almanac. — ^The  times  of  the  mean  periodical  revolu- 
tions have  been  already  mentioned  ;  but  they  are  fubje6l  to  fuch  inequalities  of  motion  a6 
require  the  following  equations  for  afcertaining  their  apparent  places  :  viz. 

X.  For  the  Ijght  which  depends  upon  Jupiter's  eccentricity  :  %.  For  the  light  which  de- 
pends upon  his  change  of  place  in  his  orbit :  3.  For  his  anomaly  :  4.  For  the  mutual  gravita- 
tion of  tlie  three  firfl,  the  period  of  which  is  upwards  of  437  days  :  5.  For  a  period  of  12 
years  for  the  third,  accruing  from  an  unknown  caufe  :  6.  For  a  fimilar  period  for  the 
fourth,  accruing  from  its  eccentricity :  7.  For  the  variable  inclination  of  the  orbit  of  the 
fpcond ;  and,  8.  for  apparent  time. — ^The  greateft;  or  grand  equation,  which  depends  upon 
Jupiter's  agomaly,  has  been  {hewn  to  be  different  in  different  years  :  with  the  firft  fatellite 
it  is  pOflible  for  it  to  amount  to  i  h.  18  min.  16  fee. ;  with  the  fecond,  to  2  h.  37  min. 
12  fee. ;  with  the  third,  to  5  h.  16  min.  32  fee. ;  .and  with  the  fourth,  to  12  h.  20'min. 
'34  fee.  at  a  certain  time  in  fome  particular  years  sbove  fpecified,  though  in  others  it  may 
be  nothing. 

From  meafurements  of  the  greateft  elongations  of  thefe  fateUites,  taken  by  a  microme- 
ter, it  does  not  appear  xxrtairi  that  their  orbits  are  elliptical,  except  that  of  the  fourth :  the 
others,  however,  are  by  analogy  fuppofed  to  be  fuch,  though  the  ellipfes  are  fo  like  circles 
that  they  may  be  confidered  as  fuch,  even  in  calculations,  without  any  apparent  error. 
The  diameters  of  thefe  orbits,  when  viewed  from  the  earth,  fubtend  but  very  fmall  angles  ; 
viz.  the  firft  fubtends  3'5S''»  the  fecond,  6'  14";  the  third,  9' 58'';  and  the  fourth, 
17'  3<j"' — The  diameters  of  each  of  the  fatellites  themfelves,  compared  to  that  of  Jupiter, 
fecm  not  to  be  accurately  known.  Mr.  Herfchell's  obfervations  make  that  of  the  firft  to  be 
not  quite  -j'^-  of  a  fecond ;  whereas,  before  his  notice,  they  were  each  confidered  to  fubtend 
an  angle  more  than  double  this  quantity  ;  for  their  diameters  were  eftimated  at.j^  or  -^goi 
Jupiter.     Future  obfervations  muft  determine  this  point. 

7  In 


Injlrumeiit  for  exhibiting  Jupitef  and  his  Moons.  T2Q 

'  In  obfervlng  the  eclipfes  of  Jupiter's  fatellites  by  his  (hadow,  it  has  been  found  that  t!ic 
duration  of  an  eclipfe  of  each  is  longer  at  fome  times  than  at  others  ;  that  in  fome  in- 
ftances  a  fatelllte  paffcs  through  the  centre  of  the  fliadow,  which  is  fuppofed  to  be  a  hi ;  c 
conical,  but  at  others  through  only  a  chord  of  its  circular  fcdion  ;  hence  an  inclination  of 
each  of  their  orbi  s  to  that  of  Jupiter  has  been  proved,  and  calculated  to  be  as  follows  : 
Of  the  firft,  about  2°S^^  the  afcendmg  node  being  at  relt  near  tiie  middle  of  Aquarius; 
of  the  fecond,  variable  from  i°  50\in  1608,,  to  5"  ,  i'  (in  i  - 15),  tiie  afcending  node  being 
at  reft  about  5°  of  Aquarius  ;  of  the  third,,  variable  from  3°  (in  1695  ,  to  5°  24'  ,,in  1765), 
its  afcending  node  being  about  25°  58'  of  Aquarius  at  this  time  (1/98),  and  moving  for- 
wards eight  minutes  in  a  year  j  and  of  the  fourth,  about  2°  40',  which  is  very  iitic  vari- 
able, the  afcending  node  being  about  the  middle  of  Aquarius. 

The  apojove  of  the  fourth  is  at  about  24^  "  of  Aries  {iT-j^),  and  moves  forward  about 
30  in  five  years. 

The  duration  of  an  eclipfe  is  the  greateft  at  the  nodes  and  fmalleft  at  the  limits:  that  of 
the  firfl;  varies  from  2  h.  i6min.  to  2  h.  7  min.  40  fee  ;  of  the  fecond,  from  2  h.  51  min. 
20  fee.  to  2  h.  13  min.  4  fee.  ;  of  the  third,  from  <  h.  35  min.  40  fee.  to  i  h.  2  min.  32  fee. ; 
and  of  the  fourth,  from  4  h.  46  min.  to  o  h.  o  min.  o  fee. 

The  two  oppoGte  points  of  the  ecliptic,  cut  by  the  plane  of  each  orbit  extended,  are 
called  the  geocentric  nodes  ;  and  a  fatellite  appears  to  move  in  an  exa£l  ftraight  line 
only  when  the  earth  is  in  one  of  thofe  ;  for  at  other  fiiuacions  of  the  earth  the  track  of 
each  appears,  though  in  a  fmall  degree,  elliptical,  aI^d  the  more  fo  the  farther  the  earth  is 
removed  from  their  nodes  :  this  is  moft  apparent  with  the  fourth,  notwithftanding  the 
ncides  are  all  in  the  fame  figns,  by  reafon  of  the  greatnefs  of  its  orbit ;  for,  when  near 
either  limit,  it  entirely  efcapes  an  occultation,  nor  is  eclipfed  if  removed  above  52°  from 
either  node.  This  happens  to  be  the  cafe  this  year,  and  will  continue  fo  nearly,  if  not 
quite,  throughout  the  next ;   and  recurs  for  nearly  two  years  and  a  half  in  every  fix. 

The  line  in  which  the  fatellites  appear  is  nearly  horizontal,  as  on  the  fcreen,  when  Ju- 
puer  is  on  the  meridian,  but  becomes  the  more  oblique  the  farther  he  is  removed  there- 
from. ■  ■       ■  * 

The  greateil  part  of  thefe  inequalities  and  peculiarities  of  motion,  as  well  as  their  rota- 
tions, will  nor  be  attempted  to  be  illuftrated  by  the  fatellitian,  but  fuch  phenomena  only 
as  are  demonftrable'to  the  eye  of  an  obferver  independently  of  calculations,  and  which 
therefore  may  be  confidered  as  the  raoft  proper  fubje£ls  of  illuftration  by  machinery. 

After  having  given  a  defcription  of  the  fatellitian  and  its  appendages  ;  of  the  method  of 
redifying  it  for  ufe  ;  and  of  the  principal  minutiae  relating  to  the  motions  of  the  fatellites  j 
1  come  now,  in  the  laft  place,  to  particularize  thofe  phenomena  to  be  illuftrated,  which  a 
telefcope  of  a  moderate  magnifying  power  for  celeftial  obje£ls  will  prefent  to  the  obferva.. 
tion  of  a  fpeflator,  and  which  afford  a  perpetual  fource  of  amufement  to  any  perfon  who 
is  in  pofTeffion  of  a  good  inftrument.  It  is  neceflary  however  to  make  this  previous  re- 
mark, that  if  the  telefcope  invert  the  o'^jeil,  the  pofterior  furface  of  the  fcreen  mud  be 
viewed  ;  but  if  it  fhew  it  direft,  the  anterior  will  be  proper. 

"When  the  fatellitian  is  properly  reflilied,  the  fcreen  fixed  and  marked,  and  the  candle- 
ftick  adjufted  with  only  one, candle,  the  central  one  being  removed,  each. turn  of  the 

A'^ot.lL— June  1798.  S  handle 


i^O  lujiramait /or  txhihitUig  Jupiter  and  his  Moons- 

handle  will  produce  one  day's  motion  of  every  fatcllitc  5  and  a  continuation  of  flow  regular 
turn?  will  produce  a  pleaGng  view  of  the  following  plienomena  5  viz. 

1.  The  fliadows  will  move  in  nearly  a  ftraight  line. 

2.  Some  in  a  diredl  and  others  in  a  retrograde  direcllon. 

3.  The  mod  diftant  will  frequently  appear  the  neareft  to  Jupiter. 

4.  Near  Jupiter  they  will  move  the  quickcft^  and  floweil  near  tlieir  greateft  elongation^ 
where  they  become  ftationary  for  a  fhort  time. 

5.  Their  greateft  elongations  will  be  a  little  before  quadrature,  when  weft  ;  and  after, 
when  eaft  of  Jupiter. 

6.  Hence  it  will  appear,  that  the  fuperior  portion  of  each  orbit  is  greater  than  the 
inferior. 

7.  Whether  to  the  eaft  or  weft  of  Jupiter,  their  motions  will  be  dire(fl  in  the  fuperior^ 
and  retrograde  in  the  inferior,  parts  of  their  orbits. 

8.  When  pafTing  between  Jupiter  and  the  earth  (candle)  they  will  tranfit  him. 

9.  When  pafiing  the  fame  line  in  their  fuperior  femicircle  they  will  fuffer  an  occulta- 
tlon. 

1 0.  When  pafting  through  the  four  concentric  circles  they  will  be  eclipfed. 

1 1.  The  mean  or  apparent  times,  accordingly  as  the  inftrument  may  be  reftified,  of  each 
of  thefc  phenomena,  will  be  pointed  out  by  the  hour-hand,  the  name  of  the  day  by  the 
week-hand,  and  the  day  of  the  month  by  the  month-hand,  in  each  year. 

12.  If  the  candleftick  is  adjufted  frequently  for  the  fun's  place  and  Jupiter's  heliocentric 
longitude,  the  folar  fliadow  will  appear  to  alter  its  fituation  to  the  right  and  left  of  Jupi- 
ter, as  he  approaches  to  or  recedes  from  conjun£lion  or  oppofition. 

13.  The  reafon  will  be  evident,  from  the  concentric  circles,  why  an  immerfion  or  in-' 
grefs  into  Jupiter's  fhadow,  and  a  fubfequent  emerfion  or  egrefs  out  of  it,  never  both  hap- 
pen with  the  firft  and  *  fecond  fatellites  ;  nor  with  the  third,  if  Jupiter  is  within  46°  of 
oppofition  to,  or  conjunftion  with,  the  fun  ;  nor  with  the  fourth,  if  that  diftance  is  lefs- 
than  24°. 

14.  It  will  be  llkewife  evident  why  an  immerfion  only  is  vlfible  of  the  firft  and  fecond 
fatellites  from  a  conjun£tion  to  an  oppofition  (fig.  6.),  why  an  occultation  and  eclipfe  may 
be  coincident  when  at  oppofition  (fig.  5,),  and  why  an  emerfion  only  is  feen  from  an  op» 
pofitionto  a  conjun£lion  (fig.  4.). 

15.  If  a  proper  reclination  be  given  to  the  fatellitian  in  this  and  on  the  next  year,  and 
alfo  on  every  fixth  and  feventh  year  hence,  the  fourth  fatellite  will  neither  be  eclipfed  nor 
fuffer  an  occultation. 

id.  If  a  candle  be  now  placed  in  each  foctet  of  different  lengths,  as  is  reprefented  in 
fig.  3.  the  fhadow  of  the  central  one  to  cover  the  concentric  circles,  there  will  be  two  rows 
of  (liadows  on  the  fcreen  above  one  another,  one  of  which  will  reprefent  the  heliocentric> 

and  the  other  the  geocentric,  places  of  the  fatellites. 

n 

•  An  immerfion  and  fubfequent  emerfion  may  be  feen  of  the  fecond  fatelllte,  provided  it  be  near  one  of  its 
limits  at  the  fame  time  that  Jupiter  is  near  both  his  pcrihelioa  and  quadrature  with  th«  fun ;  but  this  will 
very  rarely  happen.— W.  P. 

1-7.  Hence 


liijirument  for  exhihiiing  Jtiplttr  and  his  Moans,  13 1 

1 7.  Hence  it  will  appear,  that  an  eclipfe  feen  from  the  earth  is  an  occultatioii  feen  from 
the  fun. 

18.  That  an  eclipfe  is  never  vifible  at  the  fun. 

19.  And  that  the  fliadow  of  a  fatellite,  as  feen  from  the  earth,  falls  on  Jupiter  fome- 
times  before,  fometimes  after,  and  fometimes  at  its  tranfir,  according  to  the  relative  fitua- 
tions  of  Jupiter,  the  fun,  and  earth. 

20.  If  the  central  candle  only  be  fuffered  to  remain,  and  the  little  balls  'themfelves  be 
-viewed  in  an  oblique  dire£lion,  the  reafon  vv'ill  be  apparent  why  tl^e  fatellites  arc  feen 
iunated  from  Jupiter : 

21.  And  alfo  Jupiter  Iunated  when  feen  from  them  ; 

22.  But  neither  of  them  Iunated  when  feen  from  the  earth  or  fun. 

23.  It  will  alfo  be  evident  why  the  fun  is  frequently  eclipfed  to  the  inhabitants  of  Jupi- 
ter by  the  fhadows  of  his  fatellites. 

24.  And,  lafliy,  why  the  fatellites,  as  feen  from  the  earth,  do  not  eclipfe  one  another, 
Thefe,  and  perhaps  other  phenomena  not  fpecified  here,  will  be  illuftrated  by  the  fatel- 

lltian  in  fo  diflin£l  a  manner,  as  to  convey  to  a  fpeftator,  who  may  compare  the  apparent 
motions  of  the  fliadows  to  the  real  motions  of  the  little  balls,  a  clear  conception  of  tlie  re- 
lation that  the  apparent  motions  of  Jupiter's  fatellites,  as  viewed  from  the  earth  with  a  te- 
lefcope,  have  to  their  true  circular  motions,  as  viewed  by  the  inhabitants  of  Jupiter.  But 
though  a  clear  conception  may  thus  be  formed  by  a  fpe£lator  of  the  true  and  apparent 
motions  of  the  fatellites  as  they  regard  Jupiter  himfelf,  yet  he  mud  be  informed  that  the 
real  track  in  which  they  move  round  the  fun  along  with  Jupiter,  the  progreffive  centre  of 
fheir  detached  fyftem,  is  neither  circular  nor  elliptical,  but  in  a  line  which  croffes  Jupiter's 
track  in  a  fmuofe  manner,  more  or  lefs  frequently  as  their  periods  are  (horter  or  longer. 
As  the  velocity  of  the  firft  and  fecond  fatellites  exceeds  the  velocity  of  Jupiter,  they  are 
not  only  apparently,  but  really  retrograde  in  fome  part  of  every  revolution  ;  on  which  ac- 
count their  tracks  form  loops  which  are  alternately  concave  and  convex  towards  the  fun  ; 
the  concavity  being  greater  than  the  convexity  :  but  as  the  velocity  of  Jupiter  exceeds  that 
of  the  third  and  fourth,  thefe  are  not  really  but  only  apparently  retrograde  at  the  inferior 
femicircles :  on  this  account  their  tracks  are  always  concave,  except  at  their  llationary 
points,  which  project  and  divide  the  concave  f^aces.  Thefe  real  tracks  will  eafily  be  com- 
prehended, if,  while  the  fatellites  are  in  motion,  Jupiter  himfelf  be  alfo  conceived  to  have 
a  dire£t  motion  flower  than  the  two  firft,  but  quicker  than  the  two  laft. 

If  now,  after  what  has  been  f\ud,  we  conceive  ourfelves,  like  the  philofophical  poet  *, 
conveyed  into  the  regions  of  Jupiter  and  his  fatellites,  we  (hall  with  him  find  caufe  for 
adoring  the  power,  wifdom,  and  goodnefs  of  the  Almighty  Creator  !  When  we  confidcr 
that  Jupiter,  the  diameter  of  which  planet  is  more  than  tentimes  larger  than  that  of  our 
earth,  has  a  rotation  on  its  axis  in  the  fmall  fpace  of  nine  hditrs  and  fifty-fix  minutes,  we 


■"  remote  from  day's  all-cliccring  fource. 


"  Large  Jupiter  performs  his  coiiftaiu  courfc  ; 

''  Four  friendly  moons  with  borrow 'd  luftre  rife, 

-"  iicftow  their  beams  bcniijn,  and  light  his  Ikies."''    BAteCK-JjC^/'fer/f. 

»S  2  mud 


'3*  Jupiter^s  Moons.-^Lummotis  InfeBs. 

muft  pevccive,  that,  without  the  affiflance  of  fome  other  luminary  befides  the  fun,  total 
darknefs  would  be  the  lot  of  his  inhabitants  for  nearly  five  hours  in  every  ten. — Again, 
if  we  confuler  that  Jupiter's  year,  or  periodical  revolution,  contains  4332  d.  8  h.  51I  min. 
of  our  time,  or  22936,43+  of  his  own  days,  and  that  he  has  no  fenfible  change  of  feafons, 
by  reafon  of  the  nearly  perpendicular  direftion  of  his  axis,  the  inclination  of  which  is  only 
1°  20',  we  muft  fee  that  the  number  of  his  days  in  his  year  might  frequently  be  loft,  with- 
out fome  intermediate  remembrancers  between  thofe  two  very  diftant  extremes  :  accord- 
ingly, the  Omnipotent  Father  of  the  creation  has  provided  a  remedy  for  thefe  inconve- 
jiiences  :  he  has  furnilhed  Jupiter  witli  thefe  four  moons  to  cheer  his  inhabitants  with 
light  in  the  frequent  abfence  of  the  fun's  rays,  and  to  prefent  them  with  four  diflerent 
kinds  of  months,  like  our  years,  months,  and  weeks. 

Of  the  firft  kind  of  months  in  Jupiter's  year  there  are  244,97+,  ^'^'^^  of  which  con- 
tains 9,36+  of  his  days  ;  of  the  fecond  kind  there  are  121,89  +  ,  each  containing  i8,8i  +  ; 
of  the  third  kind  there  are  60,45+,  each  comprifing  37,94+  -,  and  of  the  fourth  kind 
there  are  only  25,85  +,  each  of  which  comprifes  88,68  +  of  his  days  ;  fo  that  each  fliorter 
month,  particularly  of  tlie  three  firft  kinds,  is  very  nearly  double  the  next  longer;  and  may 
be  confidered  as  exa£i:ly  fuch,  in  counting  time  by  divifions  and  fubdivifions  of  months,  by 
the  help  of  intercalary  days. 

But  befides  thefe  ufes  of  Jupiter's  fatellltes,  and  others,  perhaps,  which  our  limited  ca- 
pacities can  never  comprehend,  there  are  three  very  confiderable  advantages,  which  the 
inhabitants  of  our  globe  poflefs,  accruing  from  the  obfervations  which  have  already  been 
made  upon  them  ;  viz.  an  accurate  knowledge  of  the  parallax  of  the  earth's  annual  orbit ; 
of  the  real  velocity  of  light ;  and  of  an  eafy  method  of  afcertaining  the  longitude  of  places 
by  land ;  all  which  are  explained  in  the  different  books  upon  aftronomy  : — fo  true  is  it 
throughout  the  whole  graml  fcale  of  nature,  that  no  individual  part  is  without  its 
utility. 

Lincoln, 
March  10,  1798. 


VI. 

ObjeBions  to  the  Opinion  of  ProfeJJor  Spallanzani  refpeEiing  the  Caufe  of  the  Light  of  Natural 
Phofphori.  Communicated  to  Mr.  John  Fabbroni,  Sub-DireBor  of  the  Royal  Mufeum  of 
Florence.     By  M,  Jo  AC  HIM  CarRADORI,  M:  D* 

XJlT  length  the  hypothefis  of  Gcsttling  is  entirely  deftroyed,  in  confequence  of  the 
refutations  of  various  celebrated  authors,  and  among  them  Spallanzani.  You  may  perhaps 
rccolleft  that  I  foretold  its  fhort  duration,  and  I  pointed  out  to  Brugnatelli,  at  its  firft  ap- 
pearance, feveral  proofs  of  its  falfity,  which  might  be  deduced  from  the  very  experiments 
it  was  built  upon. 

Though  the  refutation  ofSpallanzanifhas  not  the  merit  of  being  the  firfl,  its  excellence 

*  Annates  de  Chimie,  xxiv.  1 1 6. 

t  Chiraico  Efame  del  CUtadino  Spallanzani.    Modena,     i79<>< 

canoofr 


On  the  Light  of  Natural  Phofphiri,  '■ '  t  J  J  • 

cannot  be  difputed.     I  have  read  this  (hort  treatife  with  pleafure,  from  the  many  excellent 
and  amufing  points  of  knowledge  it  contains.     But  on  perufing  it  with  a  certain  degree^ 
of  attention,  I  cannot   avoid  making   feveral  obfervations  which   the  fafts  appear  to  - 
demand. 

It  appears  to  me  that  Spallanzani  fuppofes  himfelfto  be  the  firfl:  who  obferved  that  ■ 
water  has  the  property  of  abforbing  oxygen  from  the  air  of  the  atmofphere.  For  at  the 
1 14th  page  of  his  book,  he  fays  :  Trovai  pertanto  che  I'acqua  e'  un  mezzo  di  decomporrc 
I'arie,  come  lo  fono  il  fosforo  di  Kunckel  e  i  fulfuri  alcalini ;  ma  ella  agifce  con  eftrema  Icn- 
tezza.  "  I  found,  however,  that  water  is  a  medium  for  decompofing  the  air  in  the  fame 
manner  as  Kunckel's  phofphorus,  or  the  alcaline  fulphurets ;  but  it  a<fls  with  extreme 
flownefs." — But  this  faft  was  already  known  to  Scheele  (Treatife  of  Air  and  Fire),  and  con- 
fequently  the  honour  of  this  difcovery  is  his  right.  He  was  the  firft  who  obferved  that, 
by  keeping  a  bottle  of  atmofpheric  air  inverted  over  water  for  feveral  days,  the  water 
gradually  rifes ;  the  volume  of  air  is  diminiflied,  and  azotic  gas,  or,  as  it  was  then  called,, 
phlogiflicated  air,  remains  alone.  It  is  furprifing  that  Spallanzani  fhould  not  be  aware  o£ 
this  ;   or,  if  he  knew  it,  that  he  (hould  have  omitted  mentioning  it. 

I  have  very  Important  fa£ts  to  ilate  againft  his  theory  of  natural  phofphori.  It  Is  long 
fmce  I  firft  obferved  that  the  phofphoric  wood  not  only  Ihines  under  water  and  under  oil, 
but  even  in  the  barometric  vacuum  ;  which  obfervations  are  related  in  the  fecond  volume 
of  my  theory  of  heat.  If  the  phofphoric  wood  require  air  to  enable  it  to  fliine,  how  can 
it  continue  to  emit  light  under  oil,  where  the  vital  air  neither  exills  nor  can  have  accefs  ? 
I  muft  likewife  remark  the  difference  which  Spallanzani  has  obferved  between  the  urinous 
phofphorus  and  that  of  wood ;  namely,  that  when  the  former  is  entirely  furrounded  by 
any  pure  mephitic  air,  it  immediately  ceafes  to  give  light ;  whereas  the  other  being  placed 
in  pure  azotic  air  continues  to  fliine  during  fix  minutes,  and  does  not  entirely  lofe  its  light 
till  half  an  hour  afterwards. 

When  Spallanzani  introduced  phofphoric  wood  into  vital  air,  or  oxygen  gas,  how  did  it 
happen  that  he  omitted  to  obferve,  whether  by  its  fhining  in  that  fluid  for  a  confiderable 
time,  there  was  no  diminution  of  volume,  as  he  obferved  that  this  diminution  took  place 
when  the  phofphoric  flies  (lucciole)  were  placed  therein  ? 

The  luccioloni,  or  glow-worms,  as  well  as  the  lucciole,  fhine  under  oil.  I  have  ob- 
ferved a  luminous  fly  continue  to  fliine  perfectly  for  a  quarter  of  an  hour  in  the  barometric 
vacuum. 

Spallanzani  found  that  the  phofphorus  of  thefe  flies  fl>ines  much  more  in  oxygen  gas 
than  in  the  air  of  the  atmofphere,  and  is  totally  extinguiftied  by  air  not  capable  of  main- 
taining combuftlon.  But  how  can  we  explain  their  ftiining  under  oil  for  hours  together  ?, 
Thefa£t  is  certain,  becaufe  I  have  repeated  the  experiment  with  many  variations-;  fome- 
times  by  putting  the  phofphoric  flies  entire  beneath  the  oil,  and  fometimes  the  phofphorus  . 
«nly  detached  from  the  infcdt,  and  even  cruflied. 

This  obfervation  muft  be  well  known  to  you,  fince  I  communicated  it  laft  year  to  the 
Royal  and  Oeconomical  Society  of  Florence,  in  my  Memoir  on  the  Lucciole  ;  and  it  will: 
be  equally  known  to  the  whole  fcientific  world,  as  It  will  be  publiflied  in  the  xjiith  volume,- 
oi  the  Chemical  Annals  of  the  celebrated  Bruguatelli. 

T 


^hc 


1j^  'Ontlie  Light  of  J^^aitiyal  Phojphor'i. 

The  experiment  of  placing  the  luminous  flies  in  oxygen  is  not  new.  It  was  teforc 
made  by  Forfter;  for  which  fee  his  Theory  of  Heat,  and  the  Journal  de  Rozier  for  1784. 
He  obferved  that  they  give  much  more  heat  in  this  fluid,  not  only  at  intervals,  but  con- 
tinually. M.  Forfter  moreover  aflures  us,  that  he  difcovered  the  organs  of  refpiration  in 
thofe  infe£ls,  which  M.  Spallanzani  could  not  find.  He  defcribes  them  precifely,  by  ob- 
•ferving  that  in  each  of  the  luminous  rings  there  are  two  air  paflages,  furnilhed  with  val- 
vules at  their  apertures,  and  that  thefe  paflages  are  loft  in  the  interior  ftrudlurc  of  the 
animal. 

I  have  fecn  two  fpecies  of  luccioloni,  or  fliining  worms ;  namely,  a  larger  and  a  fmaller, 
-of  which  I  have  given  a  flight  defcription  in  my  Theory  of  Heat,  where  I  fpeak  of  phof- 
phori.  The  firft  fpecies  alfo  difl"ers  from  the  fecond  in  colour ;  the  former  being  nearly 
grey,  and  the  latter  nearly  black.  The  firft  have  much  luminous  matter  in  the  three  laft 
tings ;  and-  the  others  have  lefs  in  the  laft  ring  but  one.  Thefe  may  perhaps  have  been 
the  fpecies  obferved  by  the  Naturalift  of  Pavia.  Both  fpecies  conceal  their  phofphorus  at 
pleafure  with  the  utmoft  facility.  They  feem  therefore  to  be  aware  of  its  effeiSls,  parti- 
cularly the  fecond  fpecies. 

It  is  not  true,  as  certain  naturalifts,  as  well  as  Iil.  Spallanzani,  pretend,  that  the  lucci- 
oloni and  lucclole  are  animals  of  the  fame  fpecies,  difterent  only  in  fcx,  that  is  to  fay,  that 
-the  former  are  the  males,  and  die  latter  the  females.  I  can  afllrm  that  I  have  feen  the  luc- 
ciole  pregnant,  with  the  abdomen  filled  with  eggs  :  and  this  part,  which. before  was  fo  lumi- 
nous, had  its  phofphoric  part  very  much  diminilhed,  being  reduced  to  merely  two  points, 
and  two  fmall  lateral  portions.  The  lucciole  begin  to  difappear  precifely  at  the  time  of 
their  pregnancy,  which  is  the  caufe  why  they  conceal  themfelves.  If  they  be  fought  for 
among  the  grals  and  underwood,  they  are  found  in  this  ftate*. 

If  it  he  certain  then  that  phofphoric  wood,  the  luccioloni  and  the  lucciole  continue  to 
ihine  under  oil,  it  muft  be  admitted  that  this  light  docs  not  arife  from  a  flow  comburtion, 
as  Spallanzani  pretends,  becaufe  oil  contains  no  air  to  fupport  it.  This  is  the  legitimate 
and  immediate  confequcnce  which  muft  follow  from  this  experiment,  and  cannot  be 
refufed.  The  experiments  of  Spallanzani  lead  to  peculiar  confequences,  tliough  difTerent 
from  thofe  he  has  deduced.  It  is  poffible  that  the  unrefpirable  air  may  aft  in  a  particular 
manner  on  thefe  phofphori,  which  may  be  capable  of  preventing  the  emanation  of  their 
lights;  and  that  oxygen,  by  a  particular  aiSlion  of  a  contrary  kind,  may  augment  it. 

Why  ftiould  it  be  difputed  that  the  diff'erent  airs  may  produce  peculiar  effeds  on  thefe 
fubftances,  with  which  we  are  not  yet  acquainted  ?  To  Spallanzani  will  be  due  the  honour 
of  firft  obferving  them.  In  the  fame  manner  as  various  fluids  are  pernicious  to  natural 
phofphori,  and  prevent  their  fliining,  why  may  not  the  air  produce  the  fame  effeft  ?  I  have 
found  by  experiment,  that  the  phofphorus  of  the  lucciole  is  fuddenly  extinguilhed  if  they 
be  plunged  in  alcohol,  or  in  vinegar ;  but  continues  to  fliine  in  oil  in  the  fame  manner  as  in 
water  and  in  air. 

It  may  be  objefted  to  me,  that  Spallanzani  has  made  the  experiment,  that  the  phofpho- 
rus of  the  (hining  worms  produces  a  diminution  of  volume  in  oxygen  gas,  at  the  fame  time 


that  their  light  is  increafed  ;  whence  it 


)  be  concluded  that  the  procefs  is  analogous 


"  See  the  note  No.  i.  p.  7S.  torn.  n.  Jf  my  Theoiy  of  Htat.     C. 

o  to 


On  th  Light  of  Natural  Phofphori,  yjj 

ta  combudion.  But  this  confequence  is  -not  certain.  How  many  fubftances  arc  there 
which  have  the  property  by  their  emanations  of  altering  vital  air,  in  the  fame  manner  as 
combuftion,  which  nevertTielefs  do  not  burn  nor  emit  light?  The  fame  may  be  the  cafe 
with  the  phofphoric  matter  of  thefe  infe£ls. 

There  is  not  a  pcrfefil  analogy,  as  Spallanzani  pretends,  between  the  phofphori  he  ha« 
obferved  and  the  urinous  phofphorus,  becaufe  the  latter  does  not  (liinebut  at  a  certain  heat ; 
whereas  the  natural  phofphori  fhine  at  any  temperature  whatever,  provided  it  be  not  fo 
great  as  to  alter  their  fubftance.  This  proves,  in  my  opinion,  that  the  light  is  not  an  effect 
of  combuftion  ;  for  every  combuftion  requires  a  more  or  lefs  elevated  degree  of  heat. 

With  regard  to  the  explanation  given  by  Spallanzani  of  the  change  of  wood  into  the 
luminous  matter,  which  fuppofes  that  the  hydrogen  and  carbon,  being  fet  at  liberty,  attract 
oxygen  ;  I  will  venture  to  fay,  on  the  ftrength  of  my  experiments,  that  it  is  not  probable. 
It  is  certain  (for  I  have  obferved  it  myfelf,  and  probably  fome  others  before  me),  that 
wood,  when  luminous,  has  almoft  totally  loft  its  refmous  part,  and  that  confequently  in  that 
ftate  it  retains  fcarcely  any  either  of  the  carbonic  or  hydrogenous  principle*,  to  which  its. 
combuftibility  was  owing.  And  in  fa£l,  fuch  wood  as  has  become  luminous  is  with  dif- 
ficulty burned  in  the  fire,  and  produces  no  flame,  as  every  one  may  try.  Indeed  it  cannot 
be  otherwifc;  for  the  progrefs  of  putrefailion,  which  reduces  it  to  that  ftate,  muft  have 
deprived  it  of  mu(ii  of  its  component  parts ;  particularly  the  moft  volatile,  fuch  as  hydro- 
gen. Befides  which,  as  I  obferved  fome  months  ago  to  Brugnatelli,  I  think  very? 
differently  from  Spallanzani  with  regard  to  the  conftitution  of  thefe  fubftances ;  namely,. 
<hat  they  become  phofphorefcent  in  proportion  as  they  have  loft  their  inflammable  prinr 
ciple,  and  that  the  property  of  abforbing  and  retaining  the  light  depends  on  that  circurti- 
ilance. 

My  opinion  may  be  extended,  in  preference  to  that  of  Spallanzani,  to  the  eaufe  of  the 
phofphoric  property  of  animals  ;  for  it  is  more  reafonable  :  becaufe  we  cannot  imagine 
that  their  luminous  matter  is  either  refinous  or  oily,  and  confequently  is  not  inflammable  j, 
neither  can  it  contain  mud  carbon  or  hydrogen.  See  my  Memoirc  on  the  Lucciole,  Anu. 
Chim.  et  Hiftoriques  de  Pavle,  tom.  xiii. 

If  the  lucciole  ftiine  beneath  the  water,  as  Spallanzani  maintains,  becaufe  the  oxygen  gas 
contained  in  water  ferves  to  maintain  their  combuftion,  why  does  not  the  phofphorus  of 
Kunckel  alfo  ftiine  beneath  that  fluid  l  It  was  llkewife  neeeflary  to  have  exhibited  fome 
experiments  in  fupport  of  that  opinion ;  as  for  example,  to  have  fhewn  that  the  phof- 
phorus of  thofe  animals  alters  or  abforbs  the  vital  air  contained  (uncombined)  in  water, 
and  that  water  which  does  not  contain  it  is  not  capable  of  caufing  them  to  fhine. 
Paviay 

utpril  1$,  1797. 

*  Of  \yliat  principles,  then,  it  this  vegetable  refidue  compofcd  ?    N.- 


yii.  situk 


1 35  Sield  ef  the.  Hijory  of  Sugar. 

Vll. 

Sketch  of  the  HiJIor^'  of  Sugar,  in  the  early  Timet,  "fid  through  the  Middle  Ages  [a). 
By  W  Falconer,  M.D.  F.R.S.  isfc.  i3'c. 

A  H  E  ufe  of  fugar  is  probably  of  high,  though  not  remote  antiquity,  as  no  mention  of 
it  is  made,  as  far  as  1  can  find,  in  the  facred  writings  of  the  Old  Teltament  (i).  The  coh- 
quefts  of  Alexander  feem  to  have  opened  the  dilcoveiy  of  it  to  the  weitern  parts  of  the 
world. 

Nearchus*,  his  admiral,  found  the  fugar  cane  in  the  Eaft  Indies,  as  appears  from  his 
account  of  it,  quoted  by  Strabo  (c).  It  is  not,  however,  clear,  from  what  he  fays,  that  any 
art  was  ufed  in  bringing  the  juico  of  the  cane  to  the  confiftencc  of  fugar. 

Theophraftus  \,  who  lived  not  long  afte-,  feemsto  have  had  fome  knowledge  of  fugar,  at 
lead  of  the  cane  from  which  it  is  prepared.  In  enumerating  the  different  kinds  of  honey, 
he  mentions  one  that  is  found  in  reeds  [d),  which  mud  have  been  meant  of  fome  of  thofc 
kinds  which  produce  fugar. 

Eratofthenes  |  alfo  is  quoted  by  Strabo  (f ),  as  fpeaking  of  the  roots  of  large  reeds  found 
in  India,  which  were  fweet  ro  the  tafle  both  when  raw  and  when  boiled. 

The  next  author,  in  point  of  time,  that  makes  mention  of  fugar,  is  Varro  §,  who,  in  3 
fragment  quoted  by  Ifidorus  ;'  /"),  evidently  alludes  to  thi^  fubllance.  He  defcribes  it  as  a 
fluid,  prefled  out  from  reeds  of  a  large  fize,  which  was  fweeter  than  honey. 

Diofcorides  {g)  |1,  fpeaking  of  the  different  kinds  of  honey,  fays,  that  "  there  is  a  kind  of 
"it,  in  a  concrete  ftate,  called  fucharon,  which  is  found  in  reeds  in  India  and  Arabia 
*'  Felix.  This,  he  adds,  has  the  appearance  of  fait ;  and,  like  that,  is  brittle  when  chewed. 
"  It  is  beneficial  to  the  bowels  and  (lom:ich,  if  taken  diflblved  in  water  ;  and  is  alfo  ufeful 
"  in  difeafes  of  the  bladder  and  kidneys.     Being  fprinkled  on  the  eye,  it  removes  thofe 

(a)  Manchefter  Memoirs,  iv.  291. 

(i)  Since  writing  the  above,  I  have  obfervad  that  the  t^uieel  cane  is  mentioled  in  two  places  of  fcripturc,  and 
in  both  as  an  article  of  merchandize.  It  does  not  feem  to  have  been  the  produce  of  Judea,  a»  it  is  fpotitn  of 
a^  coming  froiVi  a  far  country.  Ifaiah,  chap,  xliii,  v.  24.  Jeremiah,  chap  r'.  v.  lo. — It  is  worthy  of  remark, 
that  the  word  fachar  Cgnifies.  in  the  Hebrew  lang\iag£,  inebriation,  which  makes  it  probable  that  the  juice  of 
ithecane  had  been  early  ufed  fortnaHIng  fome  fermented  liquor. 

(f)   EigBKE  Js  7r«giTai)Vx*X£tM«v  0T»  9rotac-i  juiXt,  fxtXta-'ruy  fxn  HFrnv.      Strabon.  L  3tv. 

(rf)  AxKn  Je  £v  Toic  xaXttjuoit.    Fragment  of  Thcophrallus  pi efcrved    in  Photius.    Sec  p.  S64.  edit.  Augfburg. 

j6oi. 

(r)  Kai  Taf  f*^*f  T«v  (fuTfliiv,  x*i  ^aXt^d  T«v  J«6ya^«v  KaXtt^wv,  yXuxEtaj  xai  ^yffEt  xcJts^jjff-Ei;     Strabon.  I.  XV. 
(/)  Indica  nam  magna  niinis  arbore  crefcit  harundo ; 
lllius  e  lentis  premitur  radicibus  humor, 
Dulcia  cui  ncqueant  fucco  contendere  mella.     Ifidor.  lib   xv^.  cap.  7. 

^^)  Eft  et  aliud  concrcti  meUis  genus,  quod  faccharon  nominatur.  In  IndiJ  vero  et  Fclici  Arabia,  in  ha- 
rjndinibus  invenitur.  Salis  modo  coaftum  eft;  dentibus,  ut  fal,  fragile  ;  ako  idoncilm  ct  ftomacho  utile,  fi  aqua 
dilutum  bibatur;  vexatge  veficje,  renibufque  auxiliatur.  lllitum  ea  difcutit,  quaeunebras  oculorum  pupiilis 
X)ffundunt.         Matthioli  Diofc.  cap.  Ixxv. 

*  Ante  Chrift.  ann.  315.        f  A.  C.  jej.        J  A.  C  Z23.       §  A.  C.  6&        |I  A.  C.  35. 

6  «« fub- 

\ 


SkilchofibeHiJofyofSugar.  *m 

■**  ful)fl.«nccs  that  ol>fcure  the  Aght."    TLe  abov«  is  the  firft  account  I  liav«  fe«n  pf  i^hc 
?ncdicinal  virtues  of  fugar. 

Galen*  appears  to  have  been  w^i\\  acquainted  with  fugar,  which  he  deferibes,  neady  as 
Dlofcorides  had  done,  as  a  kind  of  honey,  cvUl^dfiicchar^  that  came  from  India  and  Arabia 
Felix,  and  concreted  in  reeds.     He  deferibes  it  as  lefs  fweet  than  honey,  but  of  firnilar 
■qualities,  as  detergent,  deficcative,   and  digerent.     He  remarks  a  differenccj  however,  in 
tliat  fugar  is  not  Jifce  honey  injurious  to  the  ftomach,  or  produQive  of  thirft  {a). 

If  tli£  third  book  of  Galen,  *'  Upon  Miedicines  that  may  be  eajily  procured"  be  genuine,  wn 
have  reafon  to  think  fugar  could  not  be  a  fcarce  article,  as  it  is  there  repeatedly  pee- 
fcribed. 

Lucan  f  alludes  to  fugar.  In  his  third  book,  where  he  fpeaks  of  the  fweet  juices  esprefTcd 
from  reeds,  which  were  drank  by  the  people  of  India  {b). 

Seneca  |,  the  philofopher,  likewife  fpeaks  of  ao  oily  fweet  juice  in  reeds,  wlach  jprobjibly 
was  fugar  {c). 

Pliny  J  was  better  acquainted  with  this  fubflance,  wiich  -he  calls  by  tlie  name  djaccaron  \ 
and  fays,  that  it  was  brought  from  Arabia  and  India,  but  the  beft  from  the  latter  country. 
He  deferibes  it  as  a  kind  of  honey,  obtained  from  reeds,  of  a  white  colour,  rcfembling 
gum,  and  brittle  when  preffed  by  the  teeth,  and  found  in  picc€s  of  the  fize  of  a  hpzel  4>ut. 
It  was  ufed  in  medicine  only  {d). 

Salmafius,  in  his  Pliniana  Exercitationes,  fays,  that  Pliny  :relates,  upon  the  authority  of 
Juba  the  hiftorian,  that  fome  reeds  grew  in  the  Fortunate  Iflands,  which  increafed  to  the 
fize  of  trees,  and  yielded  a  liquor  that  was  fweet  and  agreeable  to  the  .paUitie.  T«his  plant 
he  concludes  to  be  the  fugar  cane  ;  but  I  think  the  paffage  in  Pliny  [e)  fcarcely  implies 
fo  much. — Hitherto  we  have  had  oo  account  of  any  artificial  preparation  of  fugar,  b^ 
boiUng  or  otherwife  ;  but  there  .is  a  paflage  in  Statius  j|,  that  feems,  if  the -reading  be  |^- 
nuine,  to  allude  to  the  boiling  of  fugar,  and  is  thought  to  refer  immediately  thereto  Iw 
"Stephens  in  his  Thefaurus  (/). 
,    .Arrlan  f ,  iu  his  Periplus  {g)  of  the  Red  Sea,  %eaks  of  the  hoaey  from  reeds,  -called 

(a)  De  fimpiic.  Medicamentis.     Lib.  vii. 

'i^b')  Quitiue  brbunt «nera  dukes  ab  arundmefaccos.     Lucani  Pliarfaiia  lib.  iii.Min.  *37. 
(.ff.)iAiuiit  iitvraiiri  apud'Indos  mel,  inurundinum  foliis,  quod  aut  ros  illius-coeli  aut  ii^fjus  atmixJinis   burner 
dulcis  et  pinguior  gignat.    Senec.  Epiftol.  1.  i.  Epift.  Ixxxiv. 

(r/)  Saccaron  Arabia  fert,  fed  laudatius  India.     Eft  autem  me!  in  aruiidinibus  collectum,  gummium  modo 
candidum,  dcntitus  fiagilc,  amptiffiraum  nucis   avcUarae   magnitudine,   ad   mediciijae  tantum   uXum,     Piin. 
Hiftor.  Natural.  1.  xii.  cap,  viii. 
'    (f)  Plin.  Hill.  Nat.  lib.  vi.  cap.  xxxii. 

(/)  Et  qnas  praecoquit  Ebofitacannas 

Largis  gratuitum  cadit  rapinis.     Stat-  Sy!r.  I.  vi.  15. 
Hatfd'fltrbie  (twiuit  Stephanus)  cannas  rntelligit  ex  quibns  faccharum  exprimitur  vel  coquitnr.  ^t  fottaiTe 
cannas  'pro  faccharo  ipfo  -pofuit.    Scd  qui  EbofitK  illi,  haKVenus  apud  neminem  invenimus-      Popu'ii  fortalltt 
funt  Indis,  ubi  faccharum  potiflimum-nafcttur.  Stcpl:!.  Thef.  VoK  Canna.    ILt'ftio  anttm  d'Jbia  eft.     Vide 
Not.  Marklandi  in  hunc  locum. 
(j)  MiXi  TO  H«X«f*iTO  TO  >.sy«,«>My  Ib;^«{i.     Page  150.  Ed.  Amftelod.  1683,  Svo. 

•*  Anno  poft  Chrift.  nat.  -143.       f  Lucani  mors,  A.  D.  65.        3'Senecae  tnots,  A.  D.  65; 
§  Plinii  mors.A.  D,  77.  jj  A.D.  circes.  '^f  A.'D.  145. 

Vol.  II.— June  1798.  T  facchar 


138  Skt'U/}  of  the  Hyfory  of  Sugni: 

facchar  (-a^aj)  as  one  of  the  articles  of  trade  between  Ariace  and  Barygaza,  two  places  of 
the  Hither  India,  and  fome  of  the  ports  on  the  Red  Sea. 

'    ^lian  *,  in  his  Natural  Hiftory,  fpeaks  of  a  kind  of  honey,  which  was  prefled  from  reeds 
that  grew  among  the  Prafii,  a  people  that  lived  near  tlie  Ganges. 

Tertullian  f  alfo  fpeaks  of  fugar,  in  his  book  De  Judiclo  Dei,  as  a  kind  of  honey  procured 
from  canes  {a). 

Alexander  Aphrodlfxus  (i)t  appears  to  have  been  acquainted  with  fugar,  which  was 
in  his  time  regarded  as  an  Indian  produdion.  He  fays,  •'  that  what  the  Indians  called 
•'  fugar,  was  a  concretion  of  honey,  in  reeds,  refembling  grains  of  fait,  of  a  white  colour, 
"  and  brittle,  and  poflefling  a  detergent  and  purgative  power  like  to  honey  ;  and  which 
"  being  boiled,  in  the  fame  manner  as  honey,  is  rendersd  lefs  purgative,  without  impairing 
"  its  nutritive  quality." 

Paulus  jEgineta  (c)  §  fpeaks  of  fugar  as  growing,  in  his  time,  in  Europe,  and  alfo  as 
brought  from  Arabia  Felix ;  the  latter  of  which  he  feems  to  think  lefs  fweet  than  the  fu- 
gar produced  in  Europe,  and  neither  injurious  to  the  flomach  nor  caufing  third,  as  the 
European  fugar  was  apt  to  do. 

Achmet  [cl),  \\  a  writer  who,  according  to  fome,  lived  about  the  year  830,  fpeaks  familiarly 
of  fugar  as  common  in  his  time. 

Avicenna  {e),  t  the  Arab  phyfician,  fpeaks  of  fugar  as  being  a  produce  of  reeds ;  but  It  ap- 
pears he  meant  the  fugar  called  Tabaxir  or  Tabarzet,  as  he  calls  it  by  that  name. 

It  does  not  appear,  that  any  of  the  above-mentioned  writers  knew  of  the  method  of  pre- 
paring fugar,  by  boiling  down  the  juice  of  the  reeds  to  a  confidence.  It  is  alfo  thouc'ht, 
the  fugar  they  had  was  not  procured  from  the  fugar-cane  in  ufe  at  prefent,  but  from  ano- 
ther of  a  larger  fize,  called  Tabarzet  (f)  by  Avicenna,  which  is  the  Arundo  Arbor  of  Cafpar 
Bauhin,  the  Saecar  Mambti  of  later  writers,  and  the  Arundo  Bambos  of  Linnaeus.  This 
yields  a  fweet.  milky  juice,  and  oftentimes  a  hard  cryftallized  matter,  exadly  refembling 
fugar,  both  in  tafte  and  appearance. 

The  hiftorians  of  the  Crufades  make  the  next  mention  of  fugar  of  any  that  have  fallen 
under  my  obfervation. 

The  author  of  the  Hiftoria  (^)**Hierofolymitana  fays,  that  the  Crufaders found  in  Syria 
certain  reeds  called  Cannameles,  of  which  it  was  reported  a  kind  of  wild  honey  was  made  ; 
but  does  not  fay  that  he  faw  any  fo  manufadtured.. 

(a)  McUa  viridanti  confragrant  pinguia  canna.     TeituUian.  de  Judicio  Dei, 

(*)  Alex.  Aphrodifaei  lib.  ii.  Probl.  79. 

(e)  Paul.  jEginela  Vox  Mc!.  MiXi.  p.  632.  Medic.  Art.  Princ.  Ed.  Henrici  Stephani,  1567. 

(4)  Vide  Meurfii  Gloff.   Graec.  Barb.  &  Du  Cange  GloiT.  ad  Script,  med.  &  inf.  Grsecitatis. 

(e)  De  Zuccaro.  Lib.  II.Traft.  II.     De  Melle.  Lib.  IL  Traft.  II. 

(f)  Some  of  the  writers  fay,  that  it  was  fo  called  from  the  name  of  a  place  !«;{<<{  TaSaffa;,  two;  b7»i  na.x~ 
uivnii!  Zujiav.  Conftantinus  a  Sccretis,  MS.  quoted  from  Du  Cange  Gloff.  Graec.  The  word  Tabarzet  figni- 
fies  white,  and  is  tranflated,  by  Du  Cange,  Saccar  Album.  Herbelot  fays,  that  the  Perfians  called  by  thiit 
name  the  hardeft  and  moft  refined  fugar.   Bibliotheque  Orientale,  p.  810, 

(g)  Par*  fecunda,  p.  595• 

•  A.  D.  circ.  145.         +  A.  D.  195.  JA.  D.  212. 

»5  A.  D.  circ.  400.  vel  fecundum  Friend  multo  pofterior.   Hift.  Medic. 

B  A.  D.  830,  fl  A.  D.  sSo.natus.  iioo. 

Albcrtisa 


Skrtch  of  tht  Hiftory  of  Stiiar.  i-^g 

Albertu'S  Agnenfis  (a)*  relates,  that  about  the  fame  period,  "  the  Crufaders  found  fweet 
"  honeyed-  reeds  in  great  quantity,  in  the  meadows  about  Tripoli,  in  Syria,  which  reeds 
"  were  called  Ziicra,  Thefe  the  people  (the  Crufaders  army)  fucked,  and  were  much 
*'  pleafed  with  the  fweet  tafte  of  them,  with  which  they  could  fcarcely  be  fatisfied.  This 
"  plant  (the  author  tells  us)  is  cultivated  with  great  labour  of  the  hufhandmen  every 
"  year.  At  the  time  of  harveft,  they  bruife  it  when  ripe  in  mortars ;  and  fet  by  the 
"  {trained  juice  in  vefl'els,  till  it  is  concreted  in  form  of  fnow,  or  of  white  fait.  This, 
•'  when  fcrapcd,  they  mix  with  bread,  or  rub  it  with  water,  and  take  it  as  pottage  ;  and  it 
"  is  to  them  more  wholefome  and  pleafing  than  the  honey  of  bees.  The  people  who  were 
*'  engaged  in  the  fieges  of  Albaria  Marra  and  Archas,  and  fuffered  dreadful  hunger,  were 
"  much  refreflied  hereby." 

The  fame  author  f,  in  the  account  of  the  reign  of  Baldwin,  mentions  eleven  camels,  laden 
with  fugar,  being  taken  by  the  Crufaders,  (b)  fo  that  it  muft  have  been  made  in  confiderable 
quantity. 

Jacobus  de  Vitriaco  mentions  J,  (c)  that  "in  Syria  reeds  grow  that  are  full  of  honey,  by 
*'  which  he  underltands  a  fweet  juice,  which  by  the  preflure  of  a  fcrew-engine,  and  con- 
*'  creted  by  fire,  becomes  fugar."  This  is  the  firft  account  I  have  met  with  of  the  employ- 
ment of  heat  or  fire  in  the  making  of  fugar. 

About  the  fame  period  §  {d)  Willermus  Tyrenfis  fpeaks  of  fugar  as  made  in  the  neighbour- 
hood of  Tyre,  and  fent  from  thence  to  the  farthefl  parts  of  the  world. 

Marlnus  Sanutus  mentions  {e)  ||,  that  in  the  countries  fubjeft  to  the  Sultan,  fugar  was  pro- 
duced in  large  quantity,  and  that  it  likewife  was  made  in  Cyprus,  Rhodes,  Amorca,  Marta, 
Sicily,  and  other  places  belonging  to  the  Chriflians. 

Hugo  Falcandus  (f)  f ,  an  author  who  wrote  about  the  time  of  the  Emperor  Frederic  Bar- 
barofla,  fpeaks  of  fugar  being  in  his  time  produced  in  great  quantity  in_Sicily.  It  appears  to 
have  been  ufed  in  two  ftates  -,  one  wherein  the  juice  was  boiled  down  to  the  conGftence  of 
honey,  and  another  where  it  was  boiled  farther,  fo  as  to  form  a  folid  body  of  fugar. 

(a)  Calamellos  ibidem  mellitos,  per  camporum  planiciem  abundanter  repertos,  quos  vocant  Zucra,  fuxit  po- 
pulus  illorum  falubri  fucco  laetatus ;  et  vix  ad  faturitatem  praedulcediae  explere  hoc  guftato  valebant.  Hoc 
enim  genus  herbae,  fummo  labore  agiicolarum,  per  fingulos  excolitur  annos.  Deinde,  tempore  meffis,  matu- 
lum  mortariolis  indigena;<:ontundunt,  fuccum  colatum  in  vafis  fuis  reponentes,  quoufque  coagulatus  induref- 
cat,  fub  fpecie  nivis  vel  falis  albi.  Qucm  rafum  cum  pane  mifcentes,  aut  cum  aqu^  tcrentes,  pro  pulmento 
fumunt ;  et  fupra  favum  mellis  guftantibus  dulce  ac  falubre  effe  videtur.  His  ergo  calamellis  melliti  faporij, 
populus  in  obfidione  Albarise  Marrae  et  Archas  multum  horrenda  fame  vexatus,  eft  refocillatus. 

Geft.  Dei  per  Francos,  p.  270. 

(b)  Gefta  Dei,  p.  353. 

(c)  Sunt  autem  calamelli,  calami  pleni  melle  fucco  dulciflimo,  ex  quo  quafi  in  torculari  oompreffo,  et  ad  ig- 
nem  condenfato,  prius  quafi  mel  pofthaec  quafi  Zuccara  efficitur.     Geft.  Dei,  p.  1075. 

(d)  Per  inftitores  ad  ultimas  orbis  partes  deportatur.     Geft.  Dei,  p.  835. 
("()  Marin.  Sanut.  L.  I.  Part  I.  Cap.  2.— in  parte  fccunda  Geft.  Dei. 
(f)  In  Prxfatione  ad  Libr.  de  Calamitatibus  Siciliae. 

*  1108.         t  mo.         +"14.         §  i"4'         111306.         fl  1170. 

T  1  have 


J'46  Oh  the  EfeSfefa-  Mixftift  ofTtn  nuhh  Geld. 

The  f-ifegoiftp;  are  all  the  paffaoes  tliat  have  occurred  to  my  reading  on  this  fubjeft, 
'they  nrf  bu?  fevv  and  incon/iderab'".  bat  may  fave  trouble  to  others,  who  are  willing  to 
make  a  deeper  enquiry  into  the  hiftory  of  this  fubftance. 

Jan.  24>  I  "90. 

The  following  pafTage,  taken  from  the  Viridarium  Franci'ci  Mendozz,  Sacrae  &:Prafan«e  Eruditionis.  Co* 
lonis  Agrippina;,  16 ;  < ,  (cems  to  point  out,  though  rather  obfcu;ely,  the  conftruftion  and  principles  of  Balloons. 

"  V'as  aereum,  plenam  aiire,  aiiter  dcmergciidura,  in  fumma  aijua  fuftentatur,  cum  ea  lit  naturahtcr  multo 
gravius ;  ergo  navis  lignea,  aut  cujuftunque  alterius  materisE  in  fummi  acris  fuperficie  conftitiita,  et  clemen- 
lari  ignc  rcplcta,  fupraaiirem  fuftintbitur,  nee  prius  in  ipfo  aere  fubmergctur,  quaiTi  navigii  gravitas  fuperet  Ic- 
vhatem  ignis,  quo  plenum  eft." 

Problema  XLVII.    Utrum  ai-r  parte  aliqua  fit  navigabilis.  W..  F. 


VIII. 

Sxperimtnts  and  Ohfervations  on  the  EffeB  of  Annealing  a  Plate  of  Metals  eonJiJlUig  ofjine  or 
ttihytd  Gold,  uiih  one  twenty-fourth  Part  of  Tin*.     By  MatiuW  Tillet. 

X.  HOUGH  the  advantage  be  great,  that  men  of  enlightened  minds  and  well  known 
artills  fliould  make  inquiries  into  the  kind  of  works  to  which  their  attention  has  been  par- 
ticularly applied,  and  (hould  render  their  obfervations  public  ;  it  is  neverthelefs  true,  that 
their  reputation,  in  many  refpedls  well  founded,  does  in  fome  inftances  caufc  the  rcfults 
drawn  from  their  experiments  to  be  too  fpeedily  adopted  ;  and  that  when  they  are  care- 
fully repeated,  it  does  not  always  happen  that  they  prove  exa£l.  Thefe  artifts,  no  doubt, 
well  informed  and  faithful  in  their  operations  and  reports,  have  not  ptetended  to  offer  them 
as  decifive ;  but  by  negleding  to  confider  the  fafls  before  them  in  every  point  of  view,  they 
have  too  fpeedily  concluded  that  thefe  fads,  univerfally  confidered,  were  fuch  as  to  them 
they  appeared  at  firft.  fight. 

Looking  over  the  Journal  de  Phyfique  for  the  month  of  September  1788, 1  faw  a  paper 
entitled  "  Experiments  and  Obfervations  on  the  Fufion  of  Gold  with  Tin,"  which  I  read 
with  great  attention,  as  being  tiie  produdion  of  a  man  of  merit  well  verfed  in  his  art, 
namely,  Mr.  Alchorne,  affay-mafter  to  the  Englilh  mint.  As  the  objeft  of  his  experi- 
ments is  interefting  to  every  arlift  who  ufes  gold  and  filver ;  as  its  aim  is  to  remove  their 
fears  refpefting  the  mixture  of  a  certain  quantify  of  tin  with  fine  or  alloyed  gold,  and  as 
thefe  artifts  do  neverthelefs  retain  their  apprehenfions  with  regard  to  the  fmalleft  mixture 
of  tin  with  the  gold  of  various  finenefs,  which  they  are  incelTantly  melting  ;  I  have  thought 
it  proper  to  repeat  the  experiments  of  Mr.  Alchorne  :  and  while  I  admit  part  of  the  fafls 
he  has  related,  I  muft  refute  thofe  which  my  own  trials  fliew  to  be  erroneous,  and  which,  if 
they  had  not  efcaped  his  attention,  wouW  doubtlefs  have  led  him  to  make  certain  excep- 
tions, in  the  too  pofitive  confequences  he  has  drawn  from  his  operations. 

Before  I  enter  upon  a  detail  of  the  e\-pcriments  of  Mr.  Alchorne,  as  well  as  my  own, 
I  think  it  proper  to  take  notice  of  the  manner  in  which  the  editor  of  the  Journal  announ- 

*  Memoirs  of  the  Academy  of  Sciences  at  Paris  far  the  year  179Q,  bting  the  concluding  volumt,  printed 
in  I797' 

CCS 


Or;  tilt  EfftB  of  a  Mt.tttixe  of  Tin  •uutlo  GaUt^  »4k 

«fs  tlie  memoir  in  queftion.  He  appears  to  be  convinced  that  tlie  worlcj  had  adopted  a» 
erroneous  opinion  relpefting  the  objedl  of  the  paper  previous  to  its  appearance  }  whence  it 
follows,  that  this  Journal,  which  is  defervedly  efteemod,  and  of  wide  circulation,  cannot 
fail  to  produce  a  ftrong  iinpreflion  in  this  refpetl,  which  ought  to  be  contradidted.  It  is 
in  fa£l  founded  on  operations  which  have  not  been  purfued  with  fuiEcient  accuracy  ;  and 
on  this  account  they  tend  to  produce  a  falfe  fecurity  in  the  mind  of  artifts  who  werk  the 
moft  precious  of  metals. 

It  has  long  been  a  received  fa£J:  among  metallurgifts,  obferves  the  editor,  that  tin  mixed 
■with  gold  in  the  fmalleft  quantity,  either  in  fubftance  or  in  vapour,  is  totally  deflruftive- 
of  the  malleability  of  that  metal.  But  Mr.  V/ouIfe,  fellow  of  the  Royal  Society  of  Lon- 
don, communicated  to  that  Society,  in  17^4,  a  memoir  of  Mr.  Alchorne,  afTayer  at  the 
Mint  in  the  Tower  of  London,  and  fince  printed  in  the  Philofophical  Tranfa£\ions,  iri 
which  he  proves,  that  tin  may  be  mixed  with  gold  in  a  moder.ate  quantity  without  pro- 
ducing thefe  bad  effects.  Thefe  experiments,  he  adds,  have  not  been  contradicted  ;  not- 
withftanding  which,  feveral  of  the  molt  celebrated  authors  have  continued  to  follow  the 
ancient  opinion,  thriagh  in  no  refpeft  founded  upon  faft.  It  may  therefore  be  fuppofed, 
that  the  memoir  of  IMr.  Alchorne  has  not  been  fufficiently  known  and  attended  to  ;  for 
which  reafon  I  have  thought  proper  to  give  an  abitra£t,  to  make  it  more  generally  known. 

M.  iilchorne  relates,  that  he  had  long  doubted  this  extraordinary  property  attributed  to 
tin  ;  and  that  an  opportunity  having  offered,  he  made  various  experiments  on  that  fubjeft. 
He  mixed  twelve  ounces  of  fine  gold  with  different  j^roportions  of  tin  from  fixty  grains  to 
half  an  ounce.  Thefe  compounds  were  beaten  under  the  hammer,  pafTcd  through  the 
laminating  rollers,  and  ftruck  in  the  fiy-prefs  without  (hewing  any  brittlenefs.  He  like- 
wife  attempted  to  expofe  gold  to  the  vapour  of  tin  ;  for  which  purpofe  he  put  twelve 
ounces  of  gold  of  22  carats  into  a  fmall  crucible,  which  he  placed  in  a  larger  crucible, 
and  furrounded  it  with  tin,  and  fubjected  the  whole  to  a  confiderable  heat  for  half  an 
hour ;  but  the  gold  loft  nothing  of  its  ductility.  He  carried  his  refearches  flill  farther  : 
he  alloyed  the  foregoing  mixtures  with  copper,  and  afterwards  added  tin  to  the  gold  thus 
alloyed  with  different  proportions  of  copper  and  fdver  ;  but  in  all  the  various  cafes,  twelve 
ounces  of  gold  alloyed  with  tin  in  the  quantity  of  half  an  ounce,  and  of  copper  two  ounces 
and  a  half,  fuffered  hammering  and  laminating  to  the  thicknefs  of  ftrong  paper,  and  could 
be  wrought  into  fmall  toys  and  drawn  into  fine  wire  with  the  fame  facility  as  the  gold  of 
commerce. 

M.  Alchorne  obfervcs,  that  the  old  opinion  adopted  by  fo  many  authors  owes  its  or!-  • 
gin  probably  to  the  arfenic  which  tin  commonly  contains,  as  he  found  that  twelve  grains 
of  that  femi-metal  in  regulus  rendered  the  fame  number  of  ounces  of  gold  brittle.  Whence 
he  concludes  that  tin,  like  the  other  bafer  metals,  does  not  injure  gold,  but  hi  proportion 
to  the  quantity  of  arfenic  it  contains,  and  that  there  is  nothing  in  tin  which  can  deprive 
gold  of  its  qualities,  as  was  before  obferved. 

From  this  fhort  account  of  the  experiments  and  obfervations  of  M.  Akiiorne,  we  (cc 
that  he  afHrms  that  gold,  whether  pure  or  alloyed,  being  fufed  with  tin  in  the  proportion  of 
one  part  of  the  former  to  twenty-four  of  the  latter,  forms  an  alloy  which  preferves  ducli- 
lity  fufficient  to  endure  hammering  and  laminating  to  the  thicknefs  of  ftrong  paper,  to  be 
ufedin  toys  and  drawn  into  fin*  wire  with  the  fame  facility  as  the  common  ftaadard  gold. 

Thoiiglt 


143  Alloy  of  Gold  u-ith  Till.'— AccouittS  of  Booh. 

Though  I  vvns  perfuaded  that  tin  deprived  gold  of  its  great  duftillty,  or  at  lead  rendei-ed  it. 
fb  brittle  that  it  could  not  be  reduced  to  thinleaves.nor  more  efpecially  be  made  to  pafs  the 
vire  plate  but  by  virtue  of  repeated  annealing,  and  peculiar  treatment  which  gold  of  the  ufual 
duclility  does  not  require,  I  neverthelefs  determined  to  repeat  the  experiments  of  Mr., 
Alchoriie,  as  well  from  efleem  for  that  Ikilful  artift,  as  to  fupply  fuch  facls  as  miglit  appear 
t-o  have  efcaped  his  notice. 

My  firft  experiment  confided  in  mixing  24  grains  of  fine  gold  with  one  of  tin,  taken 
from  an  ingot  of  this  laft  metal  which  contains  no  arfenic.  I  wrapped  this  grain  of  tin  in 
the  24  grains  of  gold  reduced  to  a  very  thin  leaf,  rendered  very  flexible  by  annealing.  I 
placed  thefe  25  grains  upon  a  piece  of  charcoal  hollowed  out,  upon  vi'hich  they  could  be 
fupported  during  their  fufion.  I  even  fprinkled  a  fmall  quantity  of  calcined  borax  upon 
the  metal,  in  order  that  the  fuGon  might  be  more  fudden,  that  the  metal  might  ?low  toge- 
ther, and  the  tin  unite  vi-ith  the  gold  without  allowing  time  for  it  to  become  calcined. 
This  alloy  was  fpeedily  fufed  by  the  enameller's  lamp,  and  reduced  into  a  fmall  button 
without  any  lofs  of  weight.  It  was  then  flattened  carefully  beneath  the  hammer  -,  but, 
iiotwithftanding  my  precaution  in  this  refpecl,  it  cracked,  and  at  laft  broke  into  three 
pieces,  its  thlcknefs  then  being  a  quarter  of  a  line  or  thereabouts. 

I  repeated  this  firfi  experiment  with  a  double  quantity  as  well  of  pure  gold  as  of  tin. 
The  refult  was  the  fame.  This  fecond  button  was  brittle,  and  likewife  broke  under  the 
hammer,  though  I  had  carefully  managed  the  procefs  of  hammering  in  order  that  this 
■  button  might  have  continued  whole  notwithftanding  the  cracks.  ' 

It  is  eafily  feen  that  thefe  experiments,  which  were  in  fome  meafure  preparatory,  tended 
to  intimate  the  confequences  I  had  reafon  to  expedl  when  I  (hould  repeat  them  more  at 
large,  and  in  a 'manner  more  nearly  refcmbling  the  experiments  with  which  I  meant  to 
compare  them. 

\To  be  concluded  in  oitr  next-l. 


ACCOUNTS    OF  BOOKS. 

Philofophical  Tranfa£lions  of  the  Royal  Society  of  London,  for  the  Year  1798.  Part  I. 
Quarto.  199  pages,  with  26  pages  of  Meteorological  Journal,  and  7  plates.  Sold  by 
Elmfly,  London. 

J.  HIS  part  contains  the  following  papers :  i.  The  Bakerian  Le£lurc.  Experiments 
upon  the  Refiftance  of  Bodies  moving  in  Fluids.  By  the  Rev.  Samuel  Vince,  A.M. 
F.R.S.  Plumian  Profeflbr  of  Aftronomy  and  Experimental  Philofophy  in  the  Univerfity 
of  Cambridge. — 2.  Experiments  and  Obfervations,  tending  to  {hew  the  compofition  and 
properties  of  Urinary  Concretions.  By  George  Pearfon,  M.D.  F.R.S. — 3.  On  the 
Cifcovery  of  four  additional  Satellites  of  the  Georgium  Sidus ;  the  retrograde  motion  of 
its  old  Satellites  announced,  and  the  caufe  of  their  difappearance  at  certain  diftances  from 
the  planet  explained.  By  William  Herfchel,  L.L.D.  F.R.S.— 4.  An  Enquiry  concern- 
ing the  Source  of  the  Heat  which  is  excited  by  Friflion.  By  Benjamin  Count  of  Rum- 
ford,  F.RS.  M.R.I.A.  (See  Philof.  Journal  II.  106.)— 5.  Obfervations  on  the  Fo- 
ramina Tliebefii  of  the  Heart.    By  Mr.  John  Abeniethy,  F.R.S.— 6.  An  Analyfis  of  the 

earthy 


Accounts  of  Boolt.  *  143 

earthy  Subftance  from  New  South  Wales,  called  Sydneia,  or  Terra  Auflralls.  By  Charles 
Hatchett,  Efq.  F.R.S.  (See  Philof.  Journal,  II.  72J.— 7.  Abftraa  of  a  Regifter  of  tha 
Barometer,  Thermometer  and  Rain,  at  Lyndon  in  Rutland,  for  the  year  1796.  By  Thomas 
Barker,  Efq. — 8.  An  Account  of  fome  Endeavours  to  afcertain  a  Standard  of  "Weight  and 
Meafure.  By.Sir  George  Shuckburgh  Evelyn,  Bart.  F.R.S.  and  A.S.— 9.  A  New  Method 
of  computing  the  Value  of  a  flowly  converging  Series,  of  which  all  the  Terms  arc  affirma- 
tive. By  the  Rev.  John  Hellins,  F.R.S.  and  Vicar  of  Potter's-Pury  in  Northamptonfliire. 
And  the  Appendix,  containing  a  Meteorological  Journal  kept  at  the  Apartments  of  the 
Royal  Society,  by  Order  of  the  Prefident  and  Council. 

Count  Rumford's  Experimental  Eflays,  Political,  Economical,  and  Philofophlcat. 
Eflay  VII. — Of  the  Propagation  of  Heat  in  Fluids.  Part  II. — An  Account  of  feveral 
New  Experiments,  with  occafional  Remarks  and  Obfervations,  and  Conjectures  re- 
fpe£ting  Chemical  Affinity  and  Solution,  and  the  Mechanical  Principle  of  Animal  Life. 
Oftavo.     75  pages,  with  2  plates.     Cadell  and  Davies.     Price  is.  6d. 

This  fecond  part  accompanies  a  new  edition  of  the  firft.  The  philofophical  world  will 
not  need  any  general  remark  on  the  interefling  nature  of  the  fubject,  nor  the  manner  in 
which  the  great  author  has  treated  it.  For  the  prefent,  I  copy  the  abridgment  of  its  Con- 
tents, and  fliall  fpeedily  give  a  fuller  account. 

Chap.  I.  Account  of  a  circumftance  of  a  private  nature,  by  which  the  author  has  beea. 
induced  to  add  this  and  the  following  chapters  to  the  fecond  edition  of  this  Eflay. — Expe- 
rimental Inveftigation  of  the  fubje£l:  continued. — Oil  found  by  experiment  to  be  a  Non:- 
conductor  of  heat. — Mercury  is  likewife  a  Non-condu£tor. — Probability  that  all  Fluids  are 
Non-condu6tors,  and  that  this  property  is  eflential  to  fluidity. — ^The  knowledge  of  that 
fa£l  may  be  of  great  ufe  in  enabling  us  to  form  more  jufl:  ideas  with  regard  to  the  nature 
of  thofe  mechanical  operations  which  take  place  in  chemical  folutions  and  combinations ; 
in  the  procefs  of  vegetation  ;  and  in  the  various  changes  efreded  by  the  powers  of  life  in 
the  animal  economy. — Rapidity  of  Solution  no  proof  of  the  exiftence  of  an  attradlion  of 
affinity.— Strata  of  frefli  water  and  of  fait  water  may  be  made  to  repofe  on  each  other  in 
aftual  contafl:,  without  mixing. — Probability  that  the  water  at  the  bottom  of  frefli  lakes, 
that  are  very  deep,  may  be  a£lually  fait  -  -  -  -         page  311 

Chap.  II.  Water  made  to  congeal  at  its  under  furface — Obfervation  refpeding  the 
formation  of  ice  at  the  bottoms  of  rivers. — Reafons  for  concluding  that  heat  can  never  be 
equally  diftributed  in  any  fluid. — Perpetual  motions  occafioned  in  fluids  by  the  unequal', 
diftribution  of  heat. — An  inconceivably  rapid  fucceffion  of  colliiions  among  the  integrant 
particles  of  fluids  is  occafioned  by  the  internal  motions  into  which  fluids  are  thrown  in  the 
propagation  of  heat. — An  attempt  to  eftimate  the  number  of  thofe  colliGons  which  take 
place  in  a  given  time. — Thefe  invelligations  will  greatly  change  our  ideas  refpetling  the 
real  ftate  of  fluids  apparently  at  reft.  Fluidity  may  be  called  the  life  of  inanimate  bodies. 
— -Conjeftures  refpedling  the  vital  principle  in  living  animals  ;  and  the  nature' of  phyfical 
ftimulation  -  -  -  -  .  pagg  332 

Chap.  3.  Probability  that  intenfe  heat  frequently  exifts  in  the  folitary  particles  of  fluids, 
which  neither  the  feeling  nor  the  fliermometer  can  deted.— The  evaporation  of  ice  during- 

I  the 


Vne  fe\rerell  ftt>ft  esphmwi  oti  tint  fappofitioft.-— Proljabilky  t&at  thr  metals  w&nld  cvapo- 
tate,  w!;en  expofeci  to  the  sfticm  of  tbt  fun's  rays,  were  they  met  good  conduKEiors  of  heat. 
■ — Mercury  is  aSually  found  to  evapornte  und«r  the  hifcati  tetnperatare  of  the  atmo^jJiere. 
irhis  fad  is  ti  fttiking  -proof  that  iflurd  inertiHry  is  a  non-corvda£bor  of  heat.— Probii'jiHiy 
that  the  heat  genevatcd  by  the  rays  of  light  is  always  the  fame  ili  intcuGtv  ;  «fld  thjit  tltofc 
cffeftS  Vrhlch  have  been  attributed  to  li'ght  ought  perhaps  in  all  cafes  to  "be  afcribed  to  th« 
aftron  of  the  heat  geiretated  by  them  :  a  flriking  proof  that  the  moil  iratenfe  laeat  does 
fometimes  exift  where  \ve  fliould  rot  expert  to  find  i't.— GoM  aftually  melted  by  the  be«t 
which  exifts  in  the  air  of  the  atrnofpliei-e,  where  there  is  no  appearance  of  fire,  or  of  «ny 
thing  red-hot. — We  ought  to  be  cautious  in  attributing  to  the  aftion  of  unknown  powers, 
€iFe£ls  fimilar  to  thofe  produced  by  the  agency  of  heat. — The  moft  intenfc  heat  may  exift 
v.'ithcut  leaving  any  vifible  traces  of  its  exiftence  behind  it. — This  important  fsiSl  illuftrated 

.  by  the  necefTary  refult -of  an  imaginary  experiment  -  -  P^^e  345 

Chap.  IV.  An  account  of  a  variety  of  mifcellaneous  experiments.-— Thermometers  witli 
cylindrical  bulbs  may  be  ufed  to  fliow  that  liquids  are  non-conduftors  of  heat. — Ice-cold 
Nvater  m  ay  be  heated  and  made  to  boil  ftanding  on  ice.— Remarkable  appeara-nces  attend- 
ing the  thawing  of  ice,  and  the  melting  of  tallow,  and  of  bees-wax,  by  meuns  of  tlie  rsi- 

.  Biant  heat  projefted  dD-vtmWards  by  a  red-hot  bullet.— Beautiful  cryftals  of  fea-falt  formed 
in  brine  (landing  on  mercury. — Olive-oil  foon  rendered  colourlefs  by  CKpofttre  to  the  air 
landing  oti  brine."— An  attempt  to  caufe  radiant  heat  from  a  red-hot  iron  bullet  to  defcend 
in  oil. — Account  of  aft  artificial  atmofpliere,  in  which  horizontal  carrerrts  were  pioduced 

:  "by  heat.  — Conjeflures  refpeiSting  the  proximate  caufes  of  the  winds  -         page  367 

A  Praftical  Effay  on  the  C!ub-Foot,  and  other  Diftortions  in  theLegs  and  Feet  of  Children, 

intended  to  fliewuwder  what  Circumftances  they  are  curable  or  otherwife;  with  thirty-one 

■Cafes,  and  the  Specification  of  a  Patent  granted  the  Author  for  his  Method  of  Praflice. 

By  T.  Sheldrake,  Trufs-maker  to  the  Weftminfter  Hofpital  and  Mary-le-bone  Infirmary. 

8vo.  S14  pages,  with  14  plates.     London:  Printed  for  Murray  andHighley,  1798. 

This  author -fliews  by  reafoning  and  induftioii,  that  the  deformity -which  forms  the  chief 

'fiibjedl  of  'his  trcatife  is  produced  by  iin  unfavourable  comprefTion  during  the  ^owth of  the 

foetus  in  uterb.     He  adduces  faSs  to  prove,  that  mechanical  means,  if  judicioufly  applied, 

■will  in  numerous  inftanccs  reftore  or  place  the  organ  in  its  proper  ftate;  and  tltat  it  is  of 

great  importance  that  ttefe  remedies  fhould  be  ufed  as  early  as  poffible  before  the  proeds 

of  ofllfication  is  confiderably  advanced  or  completed.     The  contrivance  and  application  ©f 

ihefe  means  neceflarily  demand  a  knowledge  of  the  formation  of  the  parts,  as  well  as  of;shc 

hature  of  mechanical  inftruments.     In  both  refpeds  the  author  appears  to  have  difplaycd 

confiderablc  judgment,  and  has  been  rewarded  by  fuccefs.    Itisrmpoffible  to  enter  into 

■any  detail  or  defcription  of  his  method  within  our  limits.     I  fliall  therefore  only -fey,  that 

the  nature  of  the  cafes  and  the  refpe£tability  of    the  tcftimonies  appear  to  deferve  the 

attention  of  all  wrho  from  profeffional  purfuits  or  individual  misfortune  arc  urgtd  ix)  -the 

'Confideration  of  this  fubjeil. 


ttaluJounuiLTollI.n.  V.  tacau) p.i4* . 


Fip.l 


iHiinimn. \ i \ v 


F,^.3. 


Fi^.S. 


Fi^.J. 


Fin.  6. 


Fuf.d. 


i  M  n  I T I  n  I  1 1 


Tliiloj  JoumalVotlin.VI.fcumg p.u4 . 


JOURNAL 


OP 

NATURAL  PHILOSOPHY,   CHEMISTRY, 

AND 

THE    ARTS. 


yvLT   1798. 


ARTICLE    I. 

Memoir  on  a  New  Metallic  Acid  -which  exijit  in  the  Red  Lead  of  Siberia.     By  VAU^SLIlfii 
EKtraEledfrom  the  Bulletin  of  the  Soc.  Philom.* 


B 


Y  a  new  examination  of  the  red  lead  of  Siberia,  Vauquelin  is  convinced  that  this  mi- 
neral contains  a  metallic  acid  very  difFerent  from  all  thofe  which  have  hitherto  been  known. 
The  following  are  the  principal  refults  of  his  experiments  : 

The  red  lead  ore  was  reduced  to  fine  powder,  and  boiled  in  a  faturated  folution  of  car- 
bonate of  potafli.  An  effervefcence  of  confiderable  duration  was  produced ;  the  powder 
was  diffolved,  but  foon  afterwards  a  precipitate  fell  down  of  a  yellowifli  white  colour.  The 
folvent  had  aflumed  a  beautiful  golden  colour. 

The  precipitate  proved  to  be  carbonate  of  lead. 

Nitric  acid  was  poured  into  the  alkaline  fluid  till  the  excefs  of  carbonate  of  pota'fli  was 
faturated.  The  fluid  exhibited  an  orange-red  colour.  It  was  then  mixed  with  a  fo. 
lution  of  tin,  recently  prepared,  with  which  it  aflumed  a  brown  colour,  that  afterwards 
became  greenilh.  When  poured  into  a  nitric  folution  of  lead,  it  immediately  generated 
the  red  lead.  By  fpontaneous  evaporation,  it  afforded  cryflrals  of  a  beautiful  orange  red, 
befides  thofe  of  the  nitrate  of  potafli. 

The  nitric  acid  being  poured  into  the  folution  of  the  red  cryftals  occafioned  no  preci- 
pitate ;  but  when,  after  evaporation  to  drynefs,  the  cryftals  of  nitrate  of  potafh,  which  rc- 

.  *  This  abftraft  is  tranflated  from  the  Journal  de  Phyfique,  bearing  date  for  Nov.  I794,  but  lately  printed. 

Vol.  IL— July  1798.  U  mained 


14^  New  Mitallie  Jcld. 

tnained  at  the  bottom  of  the  capfule,  were  waflieJ  with  alkohol,  n  blue  liquor  was  ob- 
tained, wliich  after  evaporatit^n  left  a  greenifli  blue  powder,  foluble  in  water,  of  an 
acid  tafte,  and  redduiinjj  the  tiii£ture  of  turnfol. 

The  red  lead  ore  may  likewife  be  decompofed  by  muriatic  acid.  If  the  latter  be  diluted 
with  water,  the  mineralizing  acid  is  precipitated  in  the  form  of  a  red  powder :  if  it  be 
concentrated,  it  re-acts  on  the  metallic  acid,  deprives  it  of  part  of  its  oxygen,  and  caufes 
it  to  pafs  to  a  deep  green  colour,  while  vapours  of  oxygenated  muriatic  acid  are  difen- 
gaged. 

Thefe  experiments  are  fufficient  to  prove  that  the  mineralizing  acid  of  the  red  lead  of 
Siberia  is  a  new  fubflance ;  but  as  it  has  fome  refemblance  with  the  molybdic  acid,  Vau- 
quclia  has  made  a  number  of  comparative  experiments  on  their  alkaline  compounds,  which 
prefented  very  evident  differences.     The  following  are  the  moft  remarkable  : 

1.  The  acid  of  Siberian  lead  ore  is  red,  when  combined  with  potafh;  the  molybdate  of 
potafh  is  white. 

2.  The  molybdate  of  potafh  affords  a  white  precipitate  with  the  nitrate  of  lead,  wherea'* 
the  red  lead  ore  is  regenerated  of  a  beautiful  orange  colour,  rcfembling  that  of  the  native 
ore  when  it  is  reduced  to  powder, 

3.  The  molybdate  of  potafh  affords  a  white  precipitate  in  flocks,  when  added  to  the  ni- 
tric folution  of  mercury.  The  fait  formed  by  the  fame  alkali  and  the  acid  of  Siberian  red' 
lead  affords  a  precipitate  of  a  deep  cinnabar  colour. 

4.  The  former  affords  a  white  precipitate  with  the  folution  of  filver ;  the  latter  a 
precipitate  of  the  molt  beautiful  carmine  red,  which  changes  to  a  purple  red  by  expofure 
to  light. 

The  foregoing  experiments  fufhciently  prove  that  this  new  acid  is  metallic,  and  differs 
much  from  the  molybdic  acid.  It  does  not  differ  lefs  from  the  other  newly  difcovered 
metals. 

Uranium  does  not  become  acid,  and  cannot  combine  with  the  cauftic  alkalis. 

Titanium  is  foluble  in  acids,  with  which  it  forms  cryftallizablc  falts,  and  does  not  com- 
bine with  the  cauilic  alkalis. 

Tungften  becomes  yellow  in  acids  without  dUfolving,  and  affords  white  cryftallizablc 
falts  with  the  alkalis. 

The  author  has  not  purfued  this  comparative  examination,  becaufe  the  properties  of  the 
other  metallic  fubllances  are  fufficiently  known.  He  promifes  to  continue  his  refearches 
as  foon  as  he  fliall  have  procured  more  of  this  mineral. 

P.  S.  Since  this  memoir  was  read  to  the  Inftitute,  Vauquelln  has  reduced  the  mineral- 
izing acid  of  the  red  lead  ore.  This  metal  is  grey,  very  hard,  brittle,  and  eafily  cryftallizes 
in  fmall  needles.    The  nitric  acid  acidifies  it  with  confiderable  difficulty. 

H.  V.  C.  D. 


Farther 


On  the /fff<;fl!ons  and  Properiks  if  Li^htt  1 47 

n. 

Farther  Experiments  and  Obfervaihns  on  the  AffeBlons  and  Properties  of  Light.     By  Henrt 

Brougham,  jun.  Ejq* 


H 


A  VIN  G  laid  before  the  Royal  Society  an  account  of  a  courfe  of  experiments  f  on 
lightj  in  which  I  had  been  enji;aged,  and  alfo  of  the  conclufions  which  thefe  experiments' 
had  taught  me  to  draw ;  I  proceed  in  the  following  paper  to  relate  the  continuation  of  my 
obfervations  ;  which,  I  hope,  may  not  prove  wholly  uninterefting  to  fuch  as  honoured  the 
former  part  with  their  attention.  I  am  frrll  to  unfold  a  new  and,  I  think,  curious  pro- 
perty of  light,  that  may  be  indeed  reckoned  fourfold,  as  it  holds,  like  the  reft,  equally  with 
refpe<fl  to  refraction,  reflexion,  inflexion,  and  deflexion ;  thus  preferving  entire  the  fame 
beautiful  analogy  in  thefe  four  operations,  which  we  have  hitherto  remarked.  I  fhall  thea 
confider  feveral  phenomena  connedled  either  with  this,  or  with  the  properties  before  de- 
fcribed,  and  of  which  they  afford  fome  flriking  confirmations. 


Ohfervatton  i.— THE  fun  fhining  ftrongly  into  my  darkened  chamber,  T  placed,  at  a 
fmall  hole  in  the  window- fliut,  a  prifm,  with  its  refrafting  angle  (of  65°)  upwards,  fo 
jhat  the  fpedlrum  was  caft  on  a  chart  placed  at  right  angles  to  the  incident  rays,  and  four 
feet  from  the  prifm. 

In  the  rays  parallel  to  the  chart,  and  two  feet  from  it,  I  placed  a  pin,  whofe  diameter 
was  yg  of  an  inch,  and  fixed  it  fo  that  the  axis  of  its  fliadow  on  the  fpecflrum  might  be 
parallel  to  the  fides  of  the  fpeflrum  A  fet  of  images  by  reflexion  was  formed  (fimilar  to 
thofe  defcribed  above  %),  all  inclining  to  the  violet ;  but  what  I  chiefly  attended  to  at  pre- 
fent  was  their  fliape.  1  had  always  obferved  that  the  part  formed  out  of  the  red-making 
rays  was  broadelt,  and  that  the  other  parts  diminilhed  in  breadth  regularly  towards  the 
violet.  I  now  delineated  one  or  two,  at  about  three  inches  from  the  (hadow  ;  and  though 
(from  the  pin's  irregularities)  the  fides  were  by  no  means  fmooth,  yet  the  general  (hapc 
was  in  every  pin,  and  with  every  prifm  ufed,  nearly  as  reprefented  in  fig.  i.  Plate  VIE. 
divided  in  the  direction  R  A,  according  to  the  colours  of  the  fpedrum  in  which  they  were 
formed  ;  R  O  B  A  was  red,  and  the  broadeft  ;  that  is,  R  A  was  broader  than  O  B,  the 
confines  of  the  red  and  orange;    and  G  DE  V  was  the  violet,  narrowed  of  all. 

Obfervation  2. — Between  the  pin  and  the  prifm,  Vo  °f  ^"  m<:-\\  from  the  pin,  was  placed 
a  fcreen,  through  a  fmall  hole  in  which,  of  twice  the  pin's  diameter,  the  rays  of  the  fpec- 
trum  paflfed,  and  were  reflefted  into  images  by  the  pin  ;  thefe  were  pretty  diftindl  and 
well  defined,  when  received  on  a  chart  half  afoot  from  the  pin.  They  w/ere  oblong,  having 
parallel  fides  and  confufed  ends;  they  were  wholly  of  the  colour  whofe  rays  fell  on  the 
jHii,  unlefs  when  the  white,  mixed  with  thofe  at  the  confines  of  the  yellow  and  green, 

•  PUilofophical  Tranfaftions,  1797. 

f  See  Philof.  Journal  i.  551.  585. 

%  PhLlofophical  Tranfaftions  for  1796,  page  240,  or  Philofophical  Journal  i.  557. 

U  a  cauled 


148  On  the  JfeBkns  and  Properties  of  Light. 

caufed  the  images  to  be  of  all  the  colours.  When  the  prifm  was  turned  round  on  its  axis, 
fo  that  different  rays  fell  on  the  pin,  the  images  changed  their  fizes  as  well  as  their  po- 
fitions  :  they  were  largeft.  when  red,  and  leaft  when  violet. 

Obfervntion  3. — In  cafe  it  may  be  thought  that  the  fides  of  the  hole,  through  which  the 
rays  pafled  in  Obfervation  2,  by  inflecSling,  might  difpofe  them,  before  incidence,  into 
beams  of  diflerent  fizes,  I  removed  the  fcreen,  and  placed  the  pin  horizontally,  the  axis  o£ 
the  fhadow  being  now  at  right  angles  to  that  of  the  prifmatic  fpedlrum  ;  and  moving  the 
prifm  on  its  axis,  again  I  obferved  the  contraclion,  and  dilatation  of  the  images  by  re- 
fle£lion,  though  now  they  were  rather  lefs  dillinct,  from  the  greater  fize  of  the  incident 
beam  ;  and  to  fliew  that  there  was  both  a  change  of  fize  and  of  place,  without  any  manner 
of  deception,  I  placed  one  leg  of  a  pair  of  compalTes  in  a  fixed  point  of  the  fpe£i:rum,  and 
the  other  in  the  middle  point  of  an  image  formed  by  the  violet-making  rays.  The  prifm 
being  then  moved  till  the  image  became  red,  I  again  bifecled  it,  and  found  its' centre 
confiderably  beyond  the  point  of  the  compaffes,  which  was  indeed  evidently  much  nearer 
one  end  of  the  image  than  the  other;  befides  that  the  red  image,  when  meafured,  was 
longer  than  the  reft :  and  this  fatisfied  me  that  there  were  two  changes,  one  of  place, 
with  refpeft  to  the  fixed  point,  the  other  of  fize,  with  refpeft  to  the  centre  of  the 
image.  Laftly,  as  far  as  I  could  judge,  the  dilatation  and  contradtion  appeared  even  and 
uniform. 

Obfervation  4. — I  remarked  that  the  fringes  or  images,  by  flexion,  were  always  increafed 
in  fize  when  formed  out  of  red-making  rays,  and  were  lefs  in  every  other  colour,  and  leaft 
in  violet  (befides  being  moved  farther  from  the  edge  of  the  fhadow  in  the  former  rays  than 
in  the  latter) ;  and  this  agrees  with  an  obfervation  of  Sir  Ifaac  Newton,  as  far  as  he  tried 
it,  whiclv  was  with  refpeft  to  deflexion.  In  making  feveral  experiments  with  prifms,  I  hit- 
on  a  very  remarkable  confirmation  of  this.  I  obferved  on  each  fide  of  the  fpeftrum  four 
or  five  diftinft  fringes,  like  the  images  by  reflexion,  coloured  in  the  order  of  the  fpeftrum, 
but  quite  well  defined  at  the  edge,  and  even  pretty  diftin£l  at  the  end  :  they  were  alfo 
much  narrower  than  thofe  images,  but  like  them  they  inclined  much  to  the  violet,  and 
were  broadeft  in  the  red,  growing  narrower  by  degrees,  and  narroweft  of  all  in  the  violet. 
I  moved  the  prifm,  and  they  difappeared ;  but  when  the  prifm  was  brought  back  to  itsfor* 
mer'pofition,  they  alfo  returned.  1  thsn  obferved  the  prifm  in  open  light,  and  faw  that 
it  had  veins,  chiefly  opaque  and  white,  running  through  it,  and  that  there  were  feveral  of 
thefe  in  the  place  where  the  light  pafled  when  the  prifm  was  held  as  before.  But  in  cafe 
the  inclination  and  (hape  of  thefe  images  might  be  owing  to  the  irregular  order  in  which 
the  veins  were  laid,  I  held  another  prifm,  which  happened  to  have  parallel  veins  :  in  many 
pofitions  of  this  the  fringes  or  images  returned,  not  indeed  always  fo  regular  nor  always 
of  the  fame  kind  j  for  fomc  were  confufed  and  broader,  formed  (as  I  concluded  from  this 
and  their  pofition)  by  reflexion  ;  others  made  by  tranfparent  veins  and  air-bubbles  were 
alfo  irregular,  but  inclined  to  the  red,  the  violet  being  fartheft  from  the  perpendicular, 
and  thefe  were  obvioufly  caufed  by  refraftion  ;  yet  all  agreed  in  this,  that  they  were  broadeft 
in  the  red,  and  narroweft  in  the  violet  parts. 

Obfrvation  5. — I  held,  in  the  direft  rays  of  the  fun  at  half  an  inch  from  the  fmall  hole  in 
the  window-fhut,  a  glafs  tube,  free  from  fcratches  and  opaque  veins,  but,  like  moft  glafs 
that  is  not  finely  wrought,  having  its  furface  of  a  ftru6lure  fomewhat  fibrous.     When  this 

tube 


On  the  JffeBicns  afid  Properties  ef  Light.  I49 

{ube  was  (lOwly  introduced  into  the  light,  and  fo  held  that  none  of  the  rays  migJit  be  re- 
frafted,  a  ftreak,  chiefly  white,  was  feen,  fimilar  in  (hape  and  pofition  to  thofe  defcribcd 
before  *.  When  narrowly  infpe£ted,  it  was  found  to  contain  many  images  by  reflexion  in  it. 
But  ihefe  were  much  diluted  by  the  abundance  of  white  light,  reflected  without  dccom- 
pofition  in  the  manner  above-mentioned  f .  This  ftreak  lay  wholly  on  one  fide  of  the  tube  j 
but  I  moved  the  tube  onward  a  little,  and  another  ftreak  darted  through  the  fhadow,  and 
extended  all  round  on  both  fides  :  and  now,  when  the  tube  was  in  the  middle  of  the  rays, 
there  were  two  ftreaks  on  both  fides,  one  a  little  feparated  from  the  other  and  continued 
through  the  ftiadow,  the  other  on  each  fide  of  the  fhadow  :  the  former  was  evidently  pro- 
duced by  refraction  :  it  contained  many  images  very  like  thofe  by  reflexion,  only  more  vivid 
in  the  colours,  which  were  all  in  the  inverted  oAder,  the  violet  being  outermoft,  and  the 
reft  neareft  the  point  of  incidence.  Images  fimilar  to  thefe  are  alfo  producible  on  the  re- 
tina, as  mentioned  before  %. 

Ohfervation  6 — I  now  placed  a  prifm  at  the  hole,  and  made  the  fame  images  by  re- 
fraiStion,  out  of  homogeneal  light.  Thefe  inclined  to  the  red,  not  (like  images  by  re- 
flexion) to  the  violet;  but  they  were  broadeft  in  the  red,  and  grevlf  narrower  towards  the 
violet  parts.  In  (hort,  when  viewed  befide  the  images  by  reflexion,  except  in  point  of 
brightnefs  and  inclination,  they  differed  from  them  in  no  refpeft. 

The  three  firll  experiments  fliew,  that  when  homogeneal  light  is  refledled,  fome  rays  arft 
conftantly  difpofed  into  larger  images  than  others  arc,  that  is,  into  images  more  diftended 
in  length,  though  of  the  fame  breadth.  The  fourth  experiment  {hews,  that  the  fame  takes 
place  when  light  is  infle£led  and  deflefted  ;  and  the  two  laft  fhew  that  the  fame  happens 
when  the  rays  are  refrafled  in  a  way  fimilar  or  analogous  to  that  in  which  the  other 
images  were  produced  by  reflexion  and  flexion. 

We  are  now  to  ftiew,  that  this  difference  of  fize  is  not  owing  to  the  different  rcflexibi- 
lities  and  flexibilities  of  the  rays.  In  order  to  this  we  fliall  both  dempnftrate,  and  then 
prove  by  experience,  "that  inflexion  and  deflexion  do  not  decompound  heterogeneous' 
rays,  whofe  dire£lion  is  fuch,  tliat  they  fall  on  the  bending  body."  In  fig.  2.  let  A  B  be ' 
the  body,  GH,  EF,  CD,  the  limits  of  its  fpheres  of  deflexion,  iiiflexion,  and  reflexion,  re- 
fpe£lively  ;  and  let  I  P  be  a  white  ray  of  dlretl  light  entering  at  P  the  fphere  of  deflexion : 
'through  P  draw  LK  at  right  angles  to  GH  ;  IP  will  be  feparated  into  PR  red,  and  PV 
violet,  and  the  five  other  colorific  rays  according  to  their  deflexibilities;  at  R  and  V  dravp 
the  perpendiculars  ST  and  QO;  then  the  alternate  angles  PRT,  RPL;  and  PVQ,  VPL 
are  equal  each  to  each.  But  TRP  and  QVP  are  the  angles  of  incidence,  at  which  the 
red  and  violet  enter  the  fphere  of  inflexion  5  and  RPL,  VPL  are  the  angles  of  deflexion  of 
the  red  and  the  violet  \  therefore  the  difference  of  the  two  latter,  that  is  RPV,  is  like- 
wife  the  difl^erence  of  thc'two  former.  Suppofe  this  difference  equal  to  nothing;  or  that 
PV  and  PR  are  parallel;'  then  rRS  the  angle  of  the  red's  inflexion  will  be  lefs  than  vVO 
the  angle  of  the  violet's  inflexion,  by  the  angle  RPV:  (when  not  evanefcent)  add  RPV 
to  rRS;  then  rRS  will  be  equal  to  vVO  :  that  is,  the  divergence  will  be  deftroyed,  and  the  . 
rays  enter  the  fphere  of  reflesion,  parallel  and  undecompounded.  It  is  evident,  therefore, 
that  t>he  effe^  arifing  from  the  different  deflexibilities  of  the  rays  is  deftroyed  by  the  equal 

*  Phil.  Tranf.  1796,  page  236.  or  Philof,  Journal  i.  555.  f  Ibid.  p.  237.  or  Phil,  Journali.  556. 

X  Ibid.  p.  143-  or  Phil.' Journal  i.  559. 


15©  On  the  JfeS?ions  and  Prcperttes  of  Light. 

and  oppofite  effedt  produced  by  their  different  inflexibilities;  and  the  fame  thing  may  in  like 
niaiiner  be  fliewn  to  happen  in  the  return  of  the  rays  from  the  body  after  reflcxioiu  But 
let  the  rays  be  fo  refledted  that  they  fliall  pafs  by  the  body  without  entering  any  more  than 
one  fphere  of  flexion ;  then  thej  will  be  feparated  by  their  flexibilities,  as  we  before  defcribed. 
It  appears,  then,  that  if  the  rays  of  light  were  not  differently  reflexible,  flexion  could  never 
produce  the  coloured  images,  by  feparating  the  compound  light.  And  indeed,  this  may  be 
eafiiy  proved  by  fad.  At  144  feet  from  the  bending  body,  the  greatefl:  fringes  by  flexion 
are  only  half.an  inch  in  length,  whereas  the  fourth  or  fifth  images  by  reflexion  are  above 
half  an  inch  at  one  foot  from  the  reflecting  furface:  the  one  fort  is  therefore  more  than 
144  times  more  diftended  than  the  other,  whereas  the  flexion  could,  at  the  very  farthel't, 
only  double  them.  AUo  the  diftin£lneff,  and  brightnefs,  and  regularity  of  the  colouring, 
are  quite  diflerent  in  the  two  cafes  ;  the  fuppofed  caufe  would  neither  account  for  the  order 
of  the  colours,  nor  for  their  abfence  in  common  fpecular  reflexion,  and  refraction  through 
two  prifras  joined  together  with  their  angles  the  contrary  ways.  Laftly,  it  we  fuppofe  the 
images  to  be  produced  by  flexion,  and  then  reflefted  from  the  body,  it  would  follow  that 
light  incident  on  a  prifm  (hould  be  decompounded,  formed  into  feveral  coloured  images, 
and  then  refratSled,  the  violet  being  leaft,  and  the  red  mod  bent ;  all  which  is  perfectly  the  re- 
verfe  ofwhatadlually  happens.  I  have  multiplied  the  proof  of  this  propofition,  perhaps  beyond 
what  is  neceffary;  but  its  great  importance  to  the  whole  theory  will,  I  hope,  plead  my  excufe; 
Let  us  now  fuppofe  that  a  homogeneal  beam  pafiTcs  through  the  fpheres  of  flexion,  it  will 
follow  that  no  divergence  can  lake  place  from  the  bending  power  of  the  body ;  fo  that  we 
have  only  to  eftimate  the  effedl  produced  by  the  reflexion,  and  to  enquire  whether  the  dif- 
ferent reflexibilities  of  the  rays  can  caufe  the  images  to  vary  their  fizes  according  as  they 
are  formed  by  different  rays.  In  fig.  3.  let  AB  be  the  body,  CD  the  limit  of  its  fphere  of 
reflexion,  and  IP  a  beam  of  homogeneal  rays,  as  red,  incident  at  P  and  refleiSted  to  R,  form- 
hig  there  the  image  Rr.  It  is  evident  that  the  greater  reflexibility  of  the  rays  IP  can  only 
alter  the  pofition  of  the  centre  of  Rr,  making  it  nearer  the  perpendicular  than  the  centre  of 
an  image  formed  by  any  other  rays  would  be.  But  the  greater  length  of  Rr  fliews  that  a 
greater  quantity  of  rays  is  refle£ted,  or  that  the  fame  quantity  is  fpread  over  a  greater  fpace, 
and  that  in  the  following  way.  Let  IF  f  i  be  a  beam  of  violet-making  rays  entering  AbCD, 
and  refle£led  fo  as  to  form  the  image  Rv.  The  force  exerted  by  AB  decrealing  according  to 
fome  law  (of  which  we  are  as  yet  ignorant)  as  the  diftance  increafes,  is  not  fufBcient  to  turn  the 
rays  back  till  they  have  come  a  certain  length  within  ABCD.  But  for  the  fame  reafon  it  turns 
back  all  that  it  does  refleft  before  they  come  nearer  than  a  certain  diftance  :  between  thefe 
two  limits,  therefore,  the  rays  are  turned  back.  But  the  limits  are  not  the  fame  to  all  the 
rays  ;  fome  begin  to  be  turned  at  a  greater  diftance  from  the  body  than  others,  and  confe- 
quentlyare  refleded  to  a  greater  diftance  from  the  middle  ray  of  the  incident  beam.  Thus 
if  IF  fi  be  changed  to  a  red-making  beam,  it  begins  to  be  turned  back  at  f,  and  the  rays 
farthcft  from  AB  are  reflefled  to  r  inftead  of  to  v,  where  they  fell  when  IF  fi  was  violet- 
making  ;  not  but  that  the  fame  quantity  of  rays  is  reflected  :  the  only  difference  is,  that  the 
moft  reflexible  are  reflefled  fartheft  from  the  body  by  their  greater  reflexibility,  and  farthefl: 
from  each  other  by  this  other  property.  Exadlly  the  fame  happens  in  the  cafe  of  refra£lion, 
mutatis  mutandis  ;  but  there  fecms  to  be  a  flight  variation  in  the  manner  in  which  the  dif- ' 
ferent  rays  are  difpofed  into  images  of  different  fizes  by  flexion.  In  this  cafe  alfo  the  bend- 
ing 


On  th  AffiSlions  and  properties  ef  Light,  -Ijl 

tng  body's  action  reaches  farther  when  exerted  on  fome  rays  than  when  exerted  on  others : 
but  then,  the  direction  of  the  rays  not  paffing  through  the  body,  thofe  which  are  fartheft  off 
and  at  too  great  a  diftance  to  be  bent,  never  coming  nearer,  are  not  bent  at  all ;  and  con- 
fequently  as  the  ieaft  flexible  rays  are  in  this  predicament  at  the  fmalleft  diilance,  and  the  , 
tnoft  flexible  not  till  the  diftance  is  greater,  the  images  formed  out  of  the  former  muft  be 
lefs  than  thofe  formed  out  of  the  latter.  This  difference  in  the  way  in  which  the  pheno- 
menon appears,  does  not  argue  the  fmalleft  difference  in  the  caufe  :  it  oa'y  follows  from  the 
different  pofition  of  the  rays,  with  refpe(^  to  the  a£ting  body,  in  the  two  cafes.  I  infer  then 
from  the  whole,  that  different  forts  of  rays  come  within  the  fpheres  of  flexion,  reflexion, 
and  refracStion,  at  different  diftances,  and  that  the  aftions  of  bodies  extend  fartheft  v/hen 
exerted  on  the  moft  flexible.  It  may  perhaps  be  confiftent  with  accuracy  and  convenience 
to  give  a  name  to  this  property  of  light ;  we  may  therefore  fay  that  the  rays  of  light  diff.r  in 
degree  of  refrangity,  reflcxity,  and  flexity,  comprehending  inflexity  and  dcflexity.  From 
thefe  terms  (uncouth  as,  like  all  new  words,  they  at  firft  appear)  no  confufion  can  arife, 
if  we  always  remember  that  they  allude  to  the  degree  of  diftance  to  which  the  rays  are  fub- 
jciS  to  the  aflion  of  bodies.  I  {hall  only  add  an  illuftration  of  this  property,  which  may 
tend  to  convey  a  clearer  idea  of  its  nature.  Suppofe  a  magnet  to  be  placed  fo  that  it  may 
attract  from  their  courfe  a  ftream  of  iron  particles,  and  let  this  ftream  pafs  at  fuch  a  dif- 
tance that  part  of  it  may  not  be  affected  at  all :  thofe  particles  which  are  attracted  may  be 
conceived  to  ftrilce  on  a  white  body  placed  beyond  the  magnet,  and  to  make  a  mark  there  of 
a  fize  proportional  to  their  number.  Let  now  another  equal  ftream  confiderably  adul- 
terated by  carbonaceous  matter,  oxygen,  &c.  pafs  by  at  the  fame  diftance,  and  in  the  fame 
diredlion.  Part  of  this  will  alfo  be  attracied,  but  not  fo  far  from  its  courfe,  nor  will  an 
equal  number  be  affected  at  all ;  fo  that  the  mark  made  on  the  white  body  will  be  nearer 
the  dire£tion  of  the  ftream,  and  of  lefs  fize  than  that  made  by  the  pure  iron.  It  matters 
not  whether  all  this  would  a6tually  happen,  even  allowing  we  could  place  the  fubjeiSts  in 
the  fituation  defcribed  :  the  thing  may  eafily  be  conceived,  and  affords  a  good  enough  illuf- 
tration of  what  happens  in  the  cafe  of  light. 

Purfuant  to  the  plan  I  before  followed,  I  now  tried  to  meafure  the  different  degrees  of  re- 
flexity,  &c.  of  the  different  rays ;  but  though  the  meafurements  which  I  took  agreed  in 
this,  that  the  red  images  were  much  larger  than  the  reft,  and  the  green  appeared  by  them  of 
a  middle  fize,  yet  they  did  not  agree  well  enough  (from  the  roughriefs  of  the  images,  and 
feveral  other  caufes  of  error)  to  authorize  us  to  conclude  with  any  certainty  "  that  the 
action  of  bodies  on  the  rays  is  in  proportion  to  the  relative  fizes  of  thefe  rays."  This,  how- 
ever, will  moft  probably  be  afterwards  found  to  be  the  cafe :  in  the  mean  time  there  is  little 
doubt  that  the  fizes  are  the  caufe  of  the  fact. 

II. 

SEVERAL  phenomena  are  eafily  explicable  on  the  principles  juft  now  laid  down. 

I.  If  a  pin,  hair,  thread,  he.  be  held  in  the  rays  of  the  fun  refraded  through  a  prifm,  ex- 
tending through  all  the  feven  colours,  a  very  fingular  deception  takes  place:  the  body  ap- 
pears of  different  fizes,  being  largeft  in  the  red,  and  decreafing  gradually  towards  the  violet. 
This  appearance  feemed  fo  extraordinary,  that  fome  friends  who  happened  to  l(:e  it  as  well  as 

o  myfclfj 


152  ■        On  the  Jff'tSl'wm  and  Propert'tes  if  Light. 

inyfelf,  fufpe£led  the  body  muft  be  irregular  m  its  fliape.  On  inverting  it,  however,  the 
fame  thing  took  place ;  and  on  turning  the  prifm  on  its  axis,  fo  that  the  difFerent  rays  fuc« 
ceflively  fell  on  the  fame  parts,  the  vifible  magnitude  of  the  body  varied  with  the  rays  that 
illuminated  it.  This  appearance  is  readily  accounted  for  by  the  different  reflcxity  of  the 
rays,  and  follows  immediately  from  Obfervation  2d  and  3d. 

2.  Sir  Ifaac  Newton  found  that  the  rings  of  colours  made  by  thin  plates,  and  by  thick 
plates  of  glafs  (as  he  calls  them),  when  formed  of  homogeneal  light,  varied  in  fize  with  the 
rays  that  made  them,  being  largeft  in  the  moft  flexible  rays.  I  have  had  the  pleafure  of  ob- 
ferving  feveral  other  forts  of  rings,  fo  extremely  fimilar,  and  formed  by  flexion,  that  I  can 
no  longer  doubt  of  this  being  alfo  the  caufe  of  the  phenomena  obferved  by  Newton.  I  fhall 
iirft  defcribe  a  fpecies,  to  prove  •'  that  the  colours  by  thick  and  thin  plates  are  one  and  the 
fame  phenomena,  only  differing  in  the  thicknefs  of  the  plates."  Happening  to  look  by 
candle  light  upon  a  round  concave  plate  of  brafs,  pretty  well  poliflied,  fo  as  to  reflect  light 
enough  for  (hewing  an  image  of  the  candle,  I  was  furprifed  to  fee  that  image  furrounded 
by  feveral  waves  of  colours,  red,  green,  and  blue,  difpofed  in  pretty  regular  order.  This 
was  fo  uncommon  in  a  metallic  fpeculum,  that  I  examined  the  thing  very  minutely  by  a 
variety  of  experiments  :  thefe  I  fhall  not  particularly  now  defcribe,  but  give  a  general  idea 
of  their  refults. 

It  muft  be  obferved,  for  the  fake  of  clearnefs,  that  in  the  following  enquiries  concerning 
the  formation  of  rings  or  fringes,  the  diameter  of  a  ring  or  fringe  means  the  line  paffmg 
through  the  centre  of  that  ring,  and  terminated  at  both  ends  by  the  circumfere'nce  ;  whereas 
the  breadth  means  that  part  of  the  diameter  intercepted  between  the  limits  of  the  ring,  or 
the  diftance  between  its  extreme  colours,  red  and  violet. 

In  the  firft  place,  they  were  formed  by  the  fun's  light  in  the  figure  of  rings,  furrounding 
the  centre  of  the  fphere  to  which  the  plate  was  ground,  at  greater  diftanccs  increafing 
their  breadths,  the  colours  pretty  bright,  though  inferior  in  brilliancy  to  thofe  of  concave 
j^cula. 

Secondly,  the  order  of  the  colours  was  in  all  red  outermoft,  and  violet  or  blue  in- 
nermoft,  with  a  greyifh-blue  fpot  in  the  colnmon  centre  of  the  whole ;  and  on  moving 
the  plate  from  the  perpendicular  pofition,  the  rings  moved  and  broke  exadlly  like  thofe  of 
;^ecula. 

In  the  third  place,  homogeneal  light  made  them  of  fimple  colours ;  they  were  broadeft 
when  red,  narrowed  when  blue  and  violet. 

Fourthly,  they  decreafed  in  breadth  from  the  centre ;  and  I  found  by  a  fimple  con- 
trivance, that  they  were  to  one  another  in  the  very  fame  ratio  that  tlie  rays  by  fpecula 
follow. 

In  the  fifth  place,  I  compared  the  general  appearance  of  the  two  forts  by  viewing  them  at 
the  fame  time,  and  was  ftruck  with  their  general  appearance,  unlels  that  thefe  of  fpecula 
were  moft  vivid  and  diftinft. 

Thefe  things  made  me  fufpeft  that  they  were  aftually  caufed  by  the  thin  coat  of  gums 
with  which  the  furface  of  the  plate  was  varniflied,  called  lacker.  Accordingly  I  took  it  off 
with  fpirit  of  wine,  znd  found  the  rings  difappear;  on  lackering  it  again  they  returned ; 
and  in  like  manner  I  caufed  a  well  finilhed  concave  metal  fpeculum  to  form  the  rings  of 
which  we  ar«  fpeaking,  by  giving  it  a  thin  coat  of  lacker.;    This  is  a  clear  proof  that  thefe 

ringa 


Jmperfeci'omfrom  Colour  in  Speculums,  153 

rings  were  exa£lly  the  fame  with  thofe  of  thick  plates  (to  ufe  Newton's  expreffion) ;  for 
the  c»at  of  gums  is,  when  thin,  pretty  tranfparent,  as  may  be  feen  by  laying  one  oa  glafs 
pJatcs. 

But  this  coat  is  extremely  thin,  and  cannot  exceed  the  2octh  part  of  an  inch  ;  fo  that  the 
colours  of  thick  plates  are  in  fa£l  the  very  fame  with  thofe  of  thin  plates,  except  that  the 
two  kinds  are  made  by  different  fized  plates.  We  cannot,  therefore,  diftinguifh  them,  any 
more  than  we  do  the  fpe£truni  made  by  a  prifm  whofe  angle  is  90"  from  that  made  by  one 
whofe  angle  is  20°.  This  kind  of  colours  is  not  the  only  one  I  have  obferved  of  nearly  the 
fame  kind  with  thofe  of  plates  ;  we  fhall  prefently  fee  another  much  more  curious  and  re- 
markable. 

III. 

IN  reflecting  on  the  obfervations  and  concluiions  contained  in  my  former  paper,  feveral 
confequences  feemed  to  follow  which  appeared  fo  new  and  uncommon,  that  I  began  to 
doubt  a  little  the  truth  of  the  premifes  ;  but  at  any  rate  was  refolved  to  examine  more  mi- 
nutely how  far  thefe  inferences  might  be  ccnfiftent  with  fa<5i :  and  I  am  happy  in  being  able 
to  announce  the  completenefs  of  that  confiftency,  even  beyond  my  expeftations.  The  chief 
confequences  were  the  following  : 

1.  That  a  fpeculum  fhould  produce,  by  flexion  and  reflexion,  colours  in  its  reflected  light 
wherever  it  has  the  leaft  fcratch  or  imperfection  on  its  furface. 

2.  That  on  great  inclinations  to  the  incident  rays  all  fpecula,  however  pure  and  highly 
poliflied,  fhould  produce  colours  by  flexion. 

3.  That  they  {hould  alfo  in  the  fame  cafe  produce  colours  by  reflexion. 

4.  That  lenfes,  having  the  finalleft  imperfections,  fhould  produce  by  flexion  colours  in 
tlieir  refradted  light. 

5.  That  there  fhould  be  many  more  than  three,  or  even  four  fringes  by  flexion,  invifibic 
to  the  naked  eye.     And,  '' 

6.  That  Iceland  cfyftal  fliould  have  fome  peculiarities  with  refpeCt  to  flexion  and  re- 
flexion ;  or  if  not,  that  fome  information  fliould  be  acquired  concerning  its  fingular  proper- 
ties refpedling  refra£tion.  * 

The  manner  in  which  the  firft  of  thefe  proportions  is  demonflrated  a  priori,  is  evident 
from  the  4th  figure,  where  CD  is  the  refleding  furface,  voa  concavity  bearing  a  fmall  ratio 
to  CD,  Ao  and  AB  rays  proceeding  to  CD.  The  one,  AB,  will  be  feparated  into  Br  red, 
and  Bv  violet,  by  deflexion  from  o,  and  will  be  refledted  to  r'  v',  forming  there  the  fringes. 
The  other,  Ao,  being  reflecSted,  will  be  feparated  into  Bx  and  By,  by  deflexion  from  v, 
forming  other  fringes,  xy,  on  the  fide  of  vo's  fhadow  oppofite  to  rV.  Alfo  when  vo  is  con- 
vex inftead  of  concave,  the  like  fringes  will  be  produced  by  the  rays  being  defle£tcd  in  paflT- 
ing  by  its  fides.  Laftly,  when  vo  is  a  poliflied  ftreak,  images  by  reflexion  will  be  produced,  as 
defcribed  Phil.  Tranf.  for  1 796,  p.  269.  (Philof.  J.  i.  593.)  The  lame  paflTage  will  alfo  fliew  the 
reafon  why,  on  great  incUnations,  colours  by  reflexion  fliould  be  produced.  And  the  fecond 
propofition,  with  refpe£t  to  flexion,  follows  from  what  was  demonftrated  in  this  paper  (p.  149 
and  150) ;  it  being  that  cafe  where  the  rays  either  leave  or  fall  on  the  fpeculum  at  fuch  an 
inclination  as  to  come  only  within  the  fphere  of  inflexion,  without  being  deflc(9ted.     The 

Vol.  II — ^JtjXY  1798.  X  fburtk 


154-  Jmpe}-fec}ii)Hs  from  Colour  In  Speculum!, 

fourth  propofition  is  merely  a  finipJe  cafe  of  flexion.     And  the  two  laft  require  no  illuftra- 
tion,     I  (hall  now  relate  how  1  inquired  into  the  truth  of  thefe  things  a  pofteriori. 

Ohftyvat'ion  i.— Locking  at  a  plane  glafs  mirror  expofed  to  the  fun's  light,  I  obfervcd  that 
up  and  down  its  furhce  there  were  minute  fcratches  (called  hairs  by  workmen),  and  that 
each  of  thefe  reflecled  a  bright  colour,  fome  red,  others  green,  and  others  blue.  On  mov- 
ing the  mirror  to  a  difll  rent  inclination,  or  my  eye  to  a  different  pofition  with  refpeil  to  the 
mirror,  I  faw  the  fpecics  of  the  colours  change  ;  the  red,  for  inftance,  became  oreen,  and 
the  green  blue.  I  applied  my  eye  clofe  to  the  mirror,  and  received  on  it  the  li"-ht  refle£ted 
from  one  hair.  I  obferved  feveral  diftinft  images  of  the  fun  much  diftended  and  regularly 
coloured,  juft  like  thofc  defcribed  above  ;  the  fame  appearances  were  obfcrvable  in  all  fpe- 
cula,  metal  and  glafs,  which  had  thefe  hairs,  and  1  ne\er  fa?/  any  metal  one  without  fome  : 
their  fize  is  exceedingly  fmall,  not  above  -^-J-^^  of  an  inch.  Rubbing  a  minute  particle  of 
greafe  on  the  furface  of  the  fpeculum,  images  were  fc-en  on  the  fibrous  furface;  and  they 
always  lay  at  right  angles  to  that  direction  in  which  the  greafe  was  difpofed  by  drawing  the 
hand  along  it. 

Ohfervatioti  2. — Befides  thefe  polifhed  hairs,  many  fpecula  have  fewer  or  more  fmall  fpecks 
and  threads,  rough  and  black.  Perhaps  every  polifhed  furface  is  fludded  with  a  number  of 
fmall  ones,  invifible  to  the  naked  eye  from  the  quantity  of  regular  light  which  it  reflefls. 
I  took,  from  a  reflecting  telefcope,  a  fmall  concave  fpeculum  not  very  well  finifhed  j  its 
furface  (hewed  feveral  fpecks  to  the  naked  eye,  and  many  with  a  microfcopc.  Its  diameter 
was  |-Jofan  inch,  its  focal  diflance  two  inches,  and  the  fphere  to  which  it  was  ground 
eight  inches  diameter.  I  placed  it  at  right  angles  to  the  rays  of  the  fun,  coming  throuo-h  a 
fmall  hole  ^of  an  inch  diameter,  into  a  very  well  darkened  room  ;  I  then  moved  it  verti- 
cally, fo  that  the  rays  might  be  refleiSled  to  a  chart  12  inches  from  the  fpeculum,  and  con- 
fequently  10  from  the  focus:  and  though  the  focus  appeared  v/hite  and  bright,^  yet  on  the 
chart,  the  broad  image  was  very  different.  It  was  mottled  with  a  vaft  number  of  dark  fpots  ;. 
thefe  were  of  two  forts  chiefly,  circular  and  oblong.  Of  the  former  a  cunfiJcrable  number 
were  diflinft  and  large,  the  reft  fmallcr  and  more  confufed,  but  fo  numerous  that  they 
feemed  to  fill  the  whole  image.  None  were  quite  black,  but  rather  of  a  blucifli  grey,  and, 
the  oblong  ones  had  a  line  of  faint  light  in  the  middle,  juft  as  is  the  cafe  in  fhadows  of  fmall 
bodies.  But  the  chief  thing  which  I  remarked  was  the  colours.  Each  oblono-  and  round 
fpot  was  bordered  by  a  gleam  of  white,  and  feveral  coloured  fringes  feparated  by  fmall. 
dark  fpaccs.  The  fringes  were  exactly  like  thofc  furrounding  the  (hadows  of  bodies,  of  the 
fame  (hape  with  the  dark  fpace,  having  the  colours  in  the  order,  red  on  the  outfide,  blue  or 
violet  in  the  infide — the  innermoft  fringe  was  broadefl,  the  others  decreafin*  in  order  from 
the  firft.  I  could  fometimes  fee  four  of  them,  and,  when  made  at  the  edge  of  the  large 
image,  I  could  indiitin£lly  difcern  the  lineaments  of  a  fifth:,  when  two  of  the  fpots  were 
very  near  one  another,  their  rings  or  fringes  ran  into  one  another,  crofling. 

Ohfervation  3. — When   the  chart  was  removed  to  a  greater  diflance,  as  fix  feet    the 
fringes  were  very  diflin£l  and  large  in  proportion  ;  alfo  the  fmaller  fpots  became  more  plain 
and  their  rings  were  feen,  though  confufedly,  from  mixing  with  one  another.     When  the 
fpeculum  was  turned  round  horizontally,  fo  that  its  inclmation  to  the  incident  rays  might 
be  greater,  the  diftance  of  the  chart  remaining  the  fame  (by  being  drawn  round  in  a  circle), 

the 


New  Procefs  for  making  Vegetable  Lahet.  l^S 

tlie  fpot&  and  fringes  evidently  were  diftended  in  breadth.     I  have  endeavoured  to  exhibit  the 

fun's  image,  as  mottled  with  fringes  or  rings  and  fpots,  in  fig.  5. 

ObfervaUon  4. — I  placed  the  fpeculum  behind  a  fcreen  with  a  hole  in  it,  through  which 

were  let  pafs  the  homogeneal  rays  of  the  fun,  feparatcd  by  refradion  through  a  prifm  ;  thil 

being  turned  on  its  axis,  the  rays  which  fell  on  the  fpeculum  were  changed  ;  the  fringes 

were  now  of  that  colour  whofe  rays  fell,  and  when  the  rays  fliifted,  the  fringes  contrafled 

or  dilated,  being  broadcft  in  the  mofl  flexible  rays,  and  confequently  in  thofe  whofe  flexity 

is  greateft. 

[Ti  le  csnitnued.'] 


III. 

Enquiries  refpeSltng  the  Colouring  Matter  of  Vegetables,  and  ihe  Atl'ion  of  Metallic  Suljlances  and 
their  Oxides  upon  them;  together  with  a  New  Prccefs  for  obtaining  Lakes  of  the  moji  in- 
ien/e  and  falid  Colours.  Read  to  the  National  Injlitute  (of  France)  1 5  Vendemiairey  in  the 
YearVL     By  the  C.GuTTON*.  ' 

J_^INN  JLUS,  the  great  naturalift  of  the  north,  had  affirmed  that  the  red  colours  of  ve- 
getables announce  the  prefence  of  an  acid.  It  was  long  ago  obferved,  that  the  juice  of  the 
violet  acquires  a  beautiful  blue  {hade  in  veffels  of  tin,  the  ufe  of  which  metal  was  recom- 
mended in  difpenfatorles  for  the  preparation  of  violet  fyrup  ;  and  the  original  colour  of  fuch 
fyrups  as  had  been  changed  by  keeping,  was  reftored  by  long  digeftion  in  tin.  Little 
attention  however  was  paid  to  the  caufe  of  thefe  phenomena  ;  and  our  aflociate,  BerthoUet, 
in  his  Elements  of  the  Art  of  Dyeing,  had  pointed  it  out  no  otherwife  than  by  conjecture, 
when  he  fuppofed  an  acid  to  have  combined  with  the  oxide  formed  at  the  furface  of  the 
tin. 

Such  was  the  ftate  of  our  knowledge  on  this  fubjeCl,  when,  from  the  ftriking  difference  of 
colour  of  two  preparations  of  the  fame  fruit,  I  undertook  to  examine  the  circumftances  in 
which  thefe  changes  take  place. 

1  fupprefs  the  detail  of  experiments  to  which  I  fubjeded  almoft  all  the  acid  coloured  fruits 
in  fuccefTion,  fuch  as  the  ftrawberry,  the  goofeberry,  the  plum,  as  well  as  the  petals 
of  flowers,  turnfol,  fernambouc,  turmeric,  &c.  by  treating  them  comparatively  in  veflels 
of  glafs,  of  porcelain,  of  metal,  and  metallic  alloys,  or  by  keeping  them  in  digeftion  on 
plates  of  metal  perfedly  cleaned,  or  upon  metallic  oxides.  I  fhall  confine  myfelf  at  prefent 
to  fuch  refults  as  may  improve  the  theory  of  vegetable  colours,  or  afford  fome  ufeful  appli- 
cations to  the  procefles  of  the  arts. 

Thefe  experiments  prove  that  the  red  colour  of  fruits  is  manifeftly  owing  to  the  real  aftion 
of  their  peculiar  acid  upon  their  colouring  matter. 

That  tin,  when  it  brightens  or  reftores  the  colour  of  violets,  docs  nothing  more  than  re- 
fume,  by  fuperior  affinity,  the  acid  which  had  caufed  it  to  turn  red. 

That  tin  or  its  oxide  is  not,  as  has  hitherto  been  thought,  the  only  metal  which  exercifes 

*  Tranflated  from  La  Decade  phJIof.  litt.  et  politique,  No,  II.  An  VI.  (J»n.  1 798.)  : 

X  2  thfs 


1 5fr  '  A'itf  Procifs  for  making  Vegetable  Lain, 

this  affinity  ;  but  that  lead,  bifmuth,  antimony,  and  zinc,  produce  the  fame  efFecl ;  that  it 
takes  place  more  fpeedily  and  completely  with  iron  ;  and  that  the  contadt  of  all  thefe  metals 
produces  a  very  perceptible  violet  tinge  in  fuch  infufions,  as  without  this  circumftance  are 
of  a  lively  and  decided  red  colour. 

That  the  green  and  acid  part  of  fruits  does  not  contain  the  colouring  principle  which  is 
difpofed  to  become  red  with  acids  ;  and  that  the  coloured  part  retains  in  combination^ 
that  portion  of  acid  which  isneceffaryto  maintain  the  ftate  of  re-aiSlion  that  determines  the- 
fliade. 

That  although  this  colouring  principle  is  nxodified  in  certain  vegetables  fo  far  as  to  refift 
acid  or  alkaline  re-agents  to  a  certain  degree,  as  fernambouc  with  regard  to  acids,  and  turn- 
fol  with  regard  to  alkalis,  yet  it  rjiay  be  brought  to  this  condition  ;  which  feems  to  fliew  thac 
it  is,  if  not  eflentially  yet  at  Icait  originally,  of  the  fame  nature. 

That  the  metallic  oxides  are  not  all  equally  proper  to  feize  and  fix  vegetable  colours; 
that  fome  among  them  appear  to  attack  them  with  more  facility,  while  others  retain  them 
with  very  little  power. 

Laftly,  thtit  the  new  metal  called  tungften,  carried  to  the  laft  degree  of  oxygenation,  which 
has  not  hitherto  been  tried  in  this  refpeft,  has  a  decided  advantage  over  all  the  other  me- 
tallic oxides  i  that  it  is  capable  of  forming  lakes  of  great  value  to  painters,  which  perfeflly- 
refift  the  proofs  of  lime-water,  of  acetic  acid  or  radical  vinegar,  of  hydro-fulphureous  gas^ 
and  even  to  a  certain  point  the  oxygenated  muriatic  acid  gas,  that  enemy  of  colours,  which; 
burns  them  fuddenly,  and,  according  to  the  expreflion  of  Citizen  Berthollet,  reprefents  in  a  few 
inftants  the  combined  action  of  air  and  light.  "We  fhall  be  lefs  furprifed  at  this  alTertion, 
when  it  is  recolleclcd  that  this  is  the  only  metallic  oxide  which  eludes  the  folvent  power  of 
the  three  mineral  acids. 

The  oxide  of  tungften  eafiiy  becomes  charged  with  the  colours  of  all  vegetable  matters. 
I  have  hitherto  found  no  more  than  one  exception  in  the  petals  of  nic-ago,  of  which  I  have 
not  been  able  to  cxtradl  the  fine  purple  red,  without  being  yet  able  to  fufpedt  the  caufe  of 
this  difference. 

In  general,  the  lakes  formed  with  this  oxide  become  deeper  inftead  of  fainter  when  they 
are  diluted.  It  is  neccfiary  to  foften  the  fliade,  I  have  remarked  that  they  acquire  ftili 
more  intenfity  when  the  oxide  has  been  previoufly  rendered  blue  by  boiling  it  in  vinegar. 

One  of  our  aflbciates,  Citizen  Vauquelin,  being  informed  of  the  objeft  of  my  refearches, 
dire£led-my  attention  to  aloes.  Citizen  dcs  Fontaines  had  the  goodnefs  to  procure  me  feveral 
kinds  I  (hall  fpeak  only  of  that  which  bears  the  name  of  foccotrrne.  I  made  experiments  on 
this  plant,  which  is  one  of  the  moft  rich  in  colour,  though  it  does  not  exhibit  the  flighteft 
appearance  while  the  equilibrium  of  its  principles  is  maintained  by  the  energy  of  vegetable 
life.  The  woody  fibre,  which  is  the  external  part,  then  fervcs  as  the  covering  of  a  very 
vifcid  matter,  of  a  greenifh  white  colour,  weakly  acid  ;  but  fcarcely  has  this  matter  been 
expofed  to  the  air  before  it  afiumes  a  very  lively  red  purp'e  colour,  which  becomes  very 
abundant  by  the  progrefs  of  fermentation.  I  have  formed  lakes  of  this  matter  with  alumine, 
oxide  of  tin,  and  the  white  oxide  of  zinc.  None  of  them  were  comparable  to  that  prepared 
with  tungften. 

1  do  not  doubt  but  that  the  oxide  of  this  new  metal  may  likewife  be  ufeful  in  the  compo- 
ition  of  colours  for  dyeing,  at  leaft  for  the  dyeing  of  filks,  which  are  not  intended  to  with- 

ftaod 


On  Camphor  and  Us  Acid,  157 

ftand  alkaline  proofs.  The  oxide  of  tin  is  ufeful  in  thefe  procelTes,  becaufe  it  is  not  eafily 
attacked  by  acids ;  but  our  oxide  is  abfolutely  info'.uble. 

1  (hall  conclude  by  a  refle£lion  which  may  render  thefe  refearches  more  interefting. 
Wolfram,  from  which  this  oxide  is  obtained,  is  found  in  the  territory  of  the  (French)  Re- 
public. .  Several  mines  are  already  known,  and  the  French  chemifts  have  been  for  fome 
years  paft  employed  in  fimplifying  the  procefles  by  which  it  is  feparated  from  foreign  fub- 
flances* . 

We  may  therefore  hope  that  the  properties  I  have  here  defcribed  will  fupply  artifl*  with 
additional  means  of  giving  durability  to  the  produftions  of  genius,  and  may  open  a  new 
branch  of  national  induflry. 


IV. 

MJiraB  of  a  Memnr  on  Camphor  and  the  Camphoric  Acid.,  read  to  the  Flrjl  Clafs  of  the 
National  Irjlitute  of  France,     By  Bouillon  LA  GjiANGE. 

[Concluded  from  Page  tor,  Vol.  II.} 

___,  Habitudes  of  Nitric  Acid  with  Camphor. 

JL  HE  nitric  acid  has  likewife  a  difFerentadion  upon  camphor  frbnv  that  which  we  have 
already  mentioned. 

The  Camphoric  Acid. 

Kofegarten  has  informed  us,  that  by  diftilling  nitric  acid'eight  times  in  fuccefllon  from 
camphor,  an  acid  is  obtained  which  differs  in  its  properties  from  the  oxalic  acid. 

As  thefe  refults  have  not  been  confirmed  by  experiment,  and 'it  has  not  been  demonflrated 
that  this  acid  is  peculiar  in  its  nature:  and  its  affinity,  I  have  repeated  the  experiments  of 
Kofegarten,  of  which  we  poflefs  only  a  fimple  notice  in  a  letter  tranflated  from  Crell's 
Journal,  and  printed  in  the  27th  volume  of  the  Journal  de  Phyfique,  page  298.  The  me- 
thod  of  preparing  this  acid  is  as  follows  : 

Firfi  P rocefi  for  preparing  the  Camphoric  Aid.-. 
Take  fourouncesj  or  122,284  grammes  of  camphor,  which  introduce-into  a  glafs  retorf^ 
and  pour  one  poundj  or  489,136  grammes  of  nitric  acid,  at  36  degrees,  or  fpecific  gravity 
1,33,  and  a\lapt  a  receiver  well  luted.  Place  the  retort  on  a  fand  bath,  and  apply  a  gradual 
hfeat.  Much  nitrous. and  carbonic  acid  gas  are  difengaged  j  part  of  the  camphor  rifeSj 
while  another  part  feiaes  the  oxigen  of  the  nitric  acid.  ,  When  the  .vapours  ceafe  to  rife,  un- 
lute  the  veffcls  ;  return  the  fublimed  camphor  into  the  retort, .pour  thereon  another  pound 
,  of  the  acid,  and  diftilla  fecond  time.  This  operation  muft  be  repeated  until  the  camphor  is 
totally  acidified.  Four  pounds- and  fourteen  ounces  of  this  nitrio  acid  are  fufficient  to  aci*^ 
dify  four  ounces  of  camphor. 

When  all  the  camphor  is  acidified  it  cryftallizes  in  the  remaining  fluid.  .  Tlie  whole 
muft  then  be  poured  on  a  filter  after  previous  decantation  of  the  acid,  and  diftilled  water 

•  Journal  desMine5,.No,  XIX.. G.    Our  Cornifh, mines  alfo^alTQid  the  ores  of  .tungftfn..N.-, 


15'  On  Camphor  and  its  Acid, 

mull  be  throwrt  on  the  cryftals  in  order  to  clear  them  of  the  portion  of  nitric  acid  which 
may  adhere  to  their  furface.  The  moll  certain  indication  that  the  cafnphor  is  acidified, 
confifts  in  its  cryftallization  by  the  cooiijig  of  the  fluid  which  remains  in  the  retort. 

Purtfcaiion  cf  the  Camphoric  Acid. 
This  acid    is   purified  by  folution  in  hot  diflilled  water,  filtration  and  evaporation  of 
rjearly  half  the  fluid,  or  till  the  period  at  which  a  flight  pellicle  is  formed.     The  cryftals  of 
camphoric  acid  feparate  by  cooling. 

ji  Second  Prvcefs. 

Another  method  of  procuring  the  camphoric  acid  confifts  in  the  ufe  of  nitric  acid  at 
50  degree?,  or  fpecific  gravity  1,532.  This  procefs  is  much  fpcedicr  than  the  former,  but 
its  inconveniences  arc  fuch  as  do  not  entitle  it  to  be  preferred  to  the  other.  In  fai5t,  the 
camphor  is  more  fpeedily  attacked  by  the  concentrated  acid ;  but  inftead  of  fubliming,  it 
pafles  over  into  the  receiver,  and  a  portion  is  likewife  carried  off"  in  the  gas  which  efcapes. 
'I'hefe  circum'ftances  occafion  a  real  lols  in  the  product,  as  may  be  feen  by  the  following 
tables  of  the  refults  : 

By  the  firft  method.  "  grammes. 

Nitric  acid,  at  36  degrees,  41b.  14  oz.  or                 -                 -  2114,538 

Camphor,  40Z.  or               -                _  _              -             -  122,284 

Acid  obtained,  i4gros,  or             -  -               -                -  53)498 

By  the  fccond  method. 

Nitric  acid,  at  50  degrees,  zlb.  12  oz.  2  gros,  or         -           -  1352,168 

Camphor,  40Z.  or                 -             -  -            -             -  122,284 

Acid  obtained,  9  gros,  or            -  -              -                -  34>392 

SECT.    vir. 

Campljor  and  Oxygenous  Gas. 

BEING  defirous  of  knowing  how  camphor  would  be  afFefled  with  oxygenous  gas,  I 
made  the  following  experiment: 

Oxygen  gas"  was  obtained  from  the  fuperoxygenated  muriate  of  pot-a(h.  After  an  in- 
verted glafs  vefTel  was  thus  filled,  it  was  transferred  to  the  trough  containing  mercury,  and 
a  fmall  portion  of  water  was  pafl'ed  to  the  furface  of  the  metallic  fluid. 

On  the  other  hand,  a  fmall  piece  of  camphor  with  a  particle  of  phofphorus  was  placed 
in  a  fmall  cupel.  A  tube  was  then  bended  in  fuch  a  manner  and  applied,  that  one  of  its 
extremities  was  placed  beneath  the  glafs  jar,  and  the  other  in  a  pneumato-chemical  trough, 
beneath  a  jar  filled  with  water. 

In  this  difpofition  of  the  apparatus  the  phofphorus  was  fet  on  fire  by  means  of  a  red-hot 
iron.  The  inflammation  was  communicated  to  the  camphor.  Much  caloric  was  difengaged 
with  a  very  brilliant  flame  ;  the  inner  furface  of  the  veflTel  became  covered  with  a  black  mat- 
ter,  which  was  detached  by  degrees,  and  floated  upon  the  water  over  the  mercury.  A  gas 
was  collefled  at  the  fame  time,  which  exhibited  all  the  charaders  of  carbonic  acid  gas. 

This  experiment  therefore  confirms  the  refult  in  Sedlion  II.  for  it  cannot  be  doubted  but 
tliat  the  matter  in  the  retort  was  a  true  carbon. 

The 


On  Camphor  and  its  Acid.  irj 

The  water  which  had  been  placed  under  the  jar  became  very  odorant,  and  its  fmell  was 
abfolutely  the  fame  as  that  of  the  oil  obtained  by  the  procelTes  already  defcribed.  It  was 
acid,  and  reddened  the  tincture  of  turnfol.  Lime  water  afcertained  the  prefence  of  carbonic 
acid  in  this  water  ;  but  upon  adding  an  excefs  of  the  carbonic  acid  the  precipitate  was  not 
taken  up  j  which  fa6t  led  to  a  fufpicion  that  another  acid  was  prefent,  and  in  faft  a  calcare- 
ous camphorate  was  obtained. 

1  obferved  that  it  was  nece/Tary  to  add  a  fmall  portion  of  phofphorus  to  the  camphor, 
which  otlierwife  would  not  have  taken  fire.  For  an  ignited  body  only  diflipates  it  in  vapour, 
and  it  cannot  be  inflamed  but  by  the  contaft  of  a  body  at  a  much  more  luminous  or  higher 
degree  of  heat. 

SECT.    Vlll. 
CharaElirs  of  the  Camphoric  Acid, 

THE  camphoric  acid  has  a  flightly  acid  bitter  tafte,  and  reddens  the  tin£lure  of  turnfol. 
It  is  cryftallizable,  and  a  mafs  of  its  cryftals  refembles  the  muriate  of  ammoniac.  By  ex- 
pofure  to  the  air  it  efBorefces.  Cold  water  diflblves  it  with  difficulty..  One  ounce  of  water 
at  the  temperature  of  lo  or  i2  degrees  of  Reaumur,  takes  up  no- more  than  fix  grains; 
whereas  at  the  boiling  heat  it  dilTolves  48  grains.  When  this  acid  is  placed  on  ignited  coals 
it  emits  a  denfe  aromatic  fume,  and  is  entirely  difllpatcd.  By  a  gentler  heat  it  melts  and, 
is  fublimed. 

If  the  camphoric  acid  be  put  into  a  porcelain  tube  (heated),  and  oxygen  gas  be  pafl'ed 
through,  the  acid  does  not  undergo  any  change,  but  is  fublimed. 

By  mere  diftillation  our  acid  firft  flows  and-  then  fublimes;  bywhich  procefs  its- proper- 
ties are  in  fome  refpe<fl  changed.  It  no  longer  reddens  the  tincture  of  turnfol,  but  acquires 
a  briflc  aromatic  fmell ;  its  tafte  becomes  lefs.  penetrating,  and  it  is  no  longer,  foluble  either 
in  water  or  the  fulphuric  and  muriatic  acids.  Heated  nitric  acid  turns  it  yellow  and  dif- 
folves  it.  Alcohol  likewife  diflblves  it ;  and  i£  this  folution  be  left  in  conta(5l  with  the  air 
of  the  atmofphere  it  cryftallizes.. 

Camphoric  acid  does  not  produce  any  change  in  fulphur  ;  alcohol  and  the  mineral  acids 
totally  diflTolve  it  ;  and  fo  likewife  do  the  volatile  and  the  fat  oils.  It  forms  combinations 
with  earths,  alkalis,,  and  metallic  fubftances..  We  fhall  give  a.  more  particular  account  of 
thefe  faline  combinations  in  another  Memoir. 

Among  metallic  folutions^it  decompofes  only  the  fulphate  and  the  muriate  of  Iron. 

It  produces  no  change  in  the  folution  of  indigo  by  fulphuric  acid,  nor  id  the  tin£lure  of- 
nutgalls.     It  has  no  aiTrion. on  lime-water.. 

Concliifion. — From  all  thefe  fafls  it  follows,  that  camphor  is  a  vohtile  oil  rendered  con- 
crete by  carbon  ;  that  thefe  two  diftindt  pr«du£ts  may  be  obt-iined  by  the  n»edium  of  alu- 
irine;  and  laftly,  that  by  treating  camphor  with  the  nitric  acid,  another  peculiar  acid  is 
obtained  which  differs  from  all  the  known  vegetable  acidf, 

I.  By  its  cryftallization.  2.  Its  fparing  folubility  in  cold  water.  3.  Its  burning  with- 
out leaving  any  refidue,-  4.  Its  not  precipitating  lime-water.  5.,  Its  producing  no  change 
in  the  fulphuric  folution  of  indigo — a  difference  which  remarkably  diflinguifhes  it  from  the 
fuberic  acid  which  turns  the  fame  folution  green;  and  6.  By  the  formation  of  peculiar  falts, 
every  one  of  which  exhibit  a  blue  flanie  with  the  blow-pipe.. 


I  tfv)  Fluids  «'»  Nil  tvttufmit  Hrai  iIew»WifrJ}- 


An  Jccouttt  offeveral  new  Experiments  en  Heat,  ivilh  occaftonal  Ri'vtarJts  and  Ohfirvatkns ;  anil 
Ccnje3ur(s  rcfpeSfing  'Chemical  Affinity  and  Solution-,  and  the  Mechanical'  Principle  cf  Animal 
Life.      By  Bli\-JAMIWt  Count  of  RumI^QKD'^- 


A 


T  the  end  oJ"  a  French  Tranflation  of  the  firft  edition  of  Count  Rumford's  Seventh 
Efl'av-,  byTiofenbr  l'i£tet,  that  Tianflator  added  the  following  extract  of  one  of  the  Count's 
private  letters  to  him',  dated  June  9,  \']c,-j  :  "I  fhould  have  been  much  furprifed  if  my 
"  Seventh  EfTay  had  not  interefted  you  ;  for  in  my  life  I  never  felt  plcafure  equal  to  that  1 
**  enjoyed  in  making  the  experiments  of  which  I  have  given  an  account  in  that  perform- 
"  ance.  You  will  perhaps  be  furprifed  when  I  tell  you,  that  I  have  fupprefTed  a  whole  chap- 
"  ter  of  interefting  fpeculation,  merely  with  a  view  of  leaving  to  others  a  tempting  field  of 
"  curious  inve!>igation  untoi^ched,  and  to  give  more  efFecl  to  my  concluding  rcfleftion, 
''  which  I  confider  as'Deing  by  far  the  moft  important  of  anv  I  have  ever  publifhed,"  As 
thefe  aflertions  were  not  originally  intended  fur  the  public  eye,  the  worthy  author  found 
his  fituation  altered  with  regard  to  the  philofophical  world  by  this  communication  ;  and 
with  a  very  honourable  degree  of  delicacy  Conceived  that  it  became  his  duty  to  let  the  pub- 
Jic  know  v.'ith  prccifion  how  far  he  had  carried  his  enquiries  in  the  inveftigation  of  the 
fuhjed  of  that  EfTay,  inftead  of  giving  obfcure  hints  of  important  fa£l;s  kept  in  refcrve,  and 
apparently  to  be  brought  forward,  when  others  might  make  tiifcoveries  of  the  fame  kind. 
The  work  before  us  contains  the  matter  in  queftion. 

The  experiments  and  obfervations  contained  in  this  Second  Part  are  as  follow : 
Chap.  I.  When  a  quantity  of  water  was  frozen  in  a  glafs  jar  by  placing  the  vefTel  in  a 
freezing  mixture,  it  was  always  obferved  that,  as  the  ice  firft  began  to  be  formed  at  the 
fides  of  the  jar,  and  gradually  increafcd  in  thicknefs,  the  portion  of  water  in  the  axis  of  the 
jar  which  lad  retained  its  fluidity,  being  compreffed  by  the  expanfion  of  the  ice,  was  forced 
upwards  towards  the  end  of  the  procefs,  and  formed  a  pointed  projection  or  nipple,  which  was 
fometimes  above  half  an  inch  higher  than  the  reft  of  the  upper  furface  of  the  ice.  This 
ft6l  induced  the  Count  to  make  experiments  relative  to  the  defeft  of  condiicSting  power  in 
fluids  downwards.  For,  if  a  fluid  be  poured  upon  this  cake  of  ice  fo  as  to  cover  the  whole 
mafs,  and  a  heated  folid  be  then  fufpended  at  a  fmall  diftance  from  the  papillary  protuberance, 
it  is  evident  that  this  iaft,  if  melted,  will  derive  its  fluidity  from  the  tranfition  of  heat,' 
through  the  fluid  of  which  the  conducing  power  or  its  abfence  was  meant  to  be  afcer- 
tained. 

In  an  experiment  with  fine  olive  oil,  the  cake  of  ice  or  congealed  water  was  three  inches 
thick,  four  inches  and  three  quarters  in  diameter,  and  the  pointed  proje£tion  rofe  half  an 
inch  above  the  upper  furface.  The  temperature  of  the  apartment  was  31  degrees  of 
Fahrenheit,  and  the  external  part  of  the  jar  as  high  as  the  ice  was  furrounded  with  a  mixture 
of  pounded  ice  and  water.  In  this  fituation  of  the  apparatus,  fine  olive  oil,  previoufly  cooled 
to  32  degrees,  was  poured  into  the  jar  till  it  ftood  at  the  height  of  three  inches  above  the 
liirface  of  the  cake  of  ice. 

*  Abridged  from  the  Seeond  Part  of  his  Sevc)ith  Experiroental  Effay. 

A  folid 


Noii'Cctidul^orj  of  Heat:  Water,  Oil,  Mercury  ^  Air,  Sieam,  P/ame.  i6t 

A  folid  cylinder  of  wrought  iron  l^  inch  in  diameter,  and  12  inches  long,  provided  with 
a  hollow  cylindrical  fheath  of  thick  paper,  was  heated  to  the  temperature  of  210  degrees  in 
boiling  water,  and,  being  fuddenly  introduced  into  its  fheath,  was  fufpcnded  from  the  ceil- 
ing of  the  room,  and  very  gradually  let  down  into  the  oil,  until  the  middle  of  the  flat  fur- 
face  jof  the  hot  iron,  which  was  diretflly  above  the  point  of  the  conical  proje£lion  of  ice,, 
was  diftant  from  it  only  2-ioths  of  an  inch.  The  end  of  the  (heath  defcended  i-ioth  of 
an  inch  lower  than  the  end  of  the  hot  metallic  cylinder.  The  ice  was  perfeflly  vifibic 
through  the  oil  in  every  ftage  of  this  experiment.  How  long  the  metallic  cylinder  was 
kept  immerfed  in  the  oil  is  not  fuid,  but  the  time  was  no  doubt  fufficient  to  fatisfy  the 
Count  that  heat  is  not  propagated  downwards  through  tliis  fluid.  The  ice  was  not  in  the 
fmalleft  degree  diminiftied,  or  otherwife  afFe(Sed,  by  the  vicinity  of  the  hot  iron. 

A  fimilar  experiment  was  made  with  a  frefti  cake  of  ice  in  the  fame  jar,  but  with  ice- 
cold  mercury  covering  the  cake  to  the  height  of  about  an  inch.  The  furfacc  of  the  mercury 
in  the  jar  was  cleaned  with  blotting  paper,  after  which  the  whole  was  fufFered  to  remain 
quiet  for  about  an  hour,  when  the  hot  cylinder  of  iron  was  very  carefully  introduced,  and 
fufi'ered  to  remain  feveral  minutes  at  the  diftance  of  a  quarter  of  an  inch  from  the  point  of 
the  conical  proje£tion  of  ice. 

In  this  as  well  as  in  the  other  experiment,  the  cylindrical  fheath  was  made  to  projeft 
i-ioth  of  an  inch  below  the  bafe  of  the  iron,  for  the  purpofe  of  diminifhing  the  internal 
motions  of  the  fluid. 

In  this  experiment  alfo  the  ice  remained  unchanged.  In  order  to  fhew  whether  the  ice 
V/ere  really  in  the  flate  of  melting  with  the  leaft  poffible  addition  of  heat,  the  Count  touched 
it  with  his  finger  beneath  the  mercury ;  and  he  found  that  this  operation  could  not  be  f« 
fueedily  performed,  but  that  figns  of  water  having  been  produced  became  apparent  on  the 
clean  and  bright  furface  of  the  mercury. 

From  the  refults  of  thefe  experimental  invefligation«,  it  appears  to  our  author  that  water, 
oil,  and  mercury,  are  perfect  non-condu£lors  of  heat ;  and  that  when  either  of  thefe  fub- 
ftances  takes  the  form  of  a  fluid,  all  interchange  and  communication  of  heat  among  its 
particles,  or  from  one  of  them  to  the  other  dirc£Hy,  become  from  that  moment  abfolutely 
imf,oJfib!e  * .  In  the  Philofophical  Tranfaflions  for  1792,  the  Count  has  fhewn  the  extreme 
imperfe£lion  of  the  conducting  power  of  air,  and  in  his  Sixth  Eflay  he  has  fhewn  how  much 
reafon  there  is  to  conclude  that  the  particles  of  fleam  and  of  flame  are  in  the  fame  predica- 
ment :  From  all  which  circumflances  he  is  difpofed  to  conclude,  that  it  is  common  to  all 
fluid',  and  even  efTential  to  fluidity,  that  they  fhall  not  immediately  or  directly  condu£l  heat 
from  particle  to  particle. 

Thi^  important  circumflance  was  applied  by  our  author,  in  the  Philofophical  Tranfaftions 
above  referred  to,  to  account  for  the  warmth  of  natural  and  artificial  clothing,  and  of 
("now,  as  well  as  to  expUin  various  phenomena  of  winds.  And  in  his  Sixth  Eflay  he 
availed  himfclf  of  the  non-condu£ting  power  of  fteam  and  of  flame,  to  explain  the  efi^6ls 
of  the  blow-pipe,  and  inveftigatc  the  mofl  advantageous  forms  for  boilers.     And,  lafliy, 

•  Oa  the  abfolute  impoffibility  of  the  tranfition  of  heat  through  fluids  at  reft,  fee  the  note  in  our  Journal, 
1.191,  It  may  however  be  obferved,  that  moft  of  the  Count's  conclufioas  will  be- praftically  true  j  thatisto 
fey,  with  regard  to  fuch  terms  of  time  as  liis  experiments  juftify.     N, 

Vol.  II,— July  1798.  Y  In 


1 62  Whether  Chemical  Affinity  he  nti  the  mere  EffeSi  of  Temperature  ^ 

in  the  third  chapter  of  the  preftnt  EITay,  he  has  'extended  the  application  of  his  dif« 
<-ov€ries  to  the  means  which  appear  to  have  been  ufed  fey  the  Creator  of  the  world,  to 
render  the  temperatures  of  different  climates  more  nearly  equal  by  means  of  the  fait  water, 
which  covers  fo  large  a  part  of  the  furface  of  the  globe.  But  the  mofV  interefting  applica- 
tion remains  to  be  made  of  this  doftrinp  to  chemiftry,  vegetation,  and  the  animal  economy  \ 
to  the  learned  in  which  branches  of  fcicnce  he  begs  leave  moft  earneftly  to  recommend 
them.  From  his  meditations  he  thinks  it  not  improbable  that  every  change  of  ftate,  in 
every  kind  of  fubftance,  may  be  owing  to  heat  a|lone ;  that  every  concretion  is  a  true  con- 
gelation efteiTted  by  cold,  or  the  diminution  of  heat;  that  every  change  from  a  fqlid 
to  a  fluid  form  is  a  real  fufion  ; — and  that  it  may  be  found,  that  the  apparent  violence  witli 
which  certain  foiids  are  attacked  by  their  folvents,  is  not  owing  to  any  particular  or  elcdlive 
^ttradion,  but  to  the  confiderable  degree  of  heat  or  cold,  find  the  great  difFerence  of  fpe- 
cific  gravity  which  enfues  in  the  folvent,  from  this  caufc  as  well  as  from  the  fubfequent 
change  produced  by  combination. 

If  fluids  be  non-conduflors  of  heat,  it  will  neceflarily  follow,  that  change  of  temperaturja 
\vill  produce  currents  in  every  chemical  folvent,  in  proportion  to  the  change  of  fpecific 
gravity  ;  and  the  rapidity  of  the  procefs  of  folution  will  be  proportioned  to  that  of  the  cur-* 
rents,  or  to  the  change  of  temperature.  And  again,  if  the  faturated  folution  be  either 
Javier  or  lighter  than  the  folvent  itfelf,  currents  will  be  produced  from  this  caufe  alfo^ 
which  wi!l  tend  to  render  the  folution  more  or  lefs  rapid,  according  to  the  magnitude  of 
this  difference,  and  its  direftion  with  regard  to  the  otner  difference  caufed  by  the  change  of 
temperature.  An  inftance  of  thefe  two  caufcs  operating  jointly  is  adduced  in  the  folution  of 
fommon  fait  in  water.  If  this  folid  be  fupported  in  a  perforated  veffd  under  water,  but 
near  its  furface,  the  folution  will  be  moft  rapid  :  flrfl:,  becaufe  the  temperature  is  dimi- 
nifhed,  and  confequently  the  water  is  condenfed  in  the  procefs  ;  and,  fecondly,  becaufe  the 
folution  of  fait  in  water  is  itfelf  more  denfe  than  the  water  itfelf.  On  both  accounts  there- 
fore the  brinp  will  rapidly  defcend,  and  frefli  portions  of  the  folvent  will  continually  be 
brought  in  contaiSl  with  the  fait. 

On  this  occafion  the  author  propofes  a  curious  queftion  :  Whether,  in  a  cafe  where  the 
expanfion  by  heat  were  equal  to  the  condenfation  by  the  procefs  of  chemical  union,  the  effe£l 
^f  folution  could  take  place? — He  anfwers  by  obferving,  that  if  chemical  attraflion,  as  has 
been  generally  fuppofed,  really  exifts  and  operates  in  the  way  of  prediledlion  beyond  the 
point  of  a6lual  contaft,  it  is  probable  that  the  folution  would  take  place. — But  if  this  at- 
jra£lion  be  nothing  mere  than  has  been  juft  pointed  out,  it  would  loUow  that  though  fclution 
would  not  be  abfolutely  impoffible,  yet  it  would  be  fo  flow  as  hardly  to  be  perceptible. 

In  the  confideration  of  the  foliition  of  fait  in  water,  the  pofition  of  the  folid  near  the 
furface  of  the  fluid,  was  ftated  as  a  circumftance  effential  to  its  rapidity.  The  uniform 
diffufion  of  foiids  tliroush  the  whole  mafs  of  lighter  fluids  which  diffolve  them,  has  ufually 
been  confidered  by  chemifts  as  a  proof  of  attraction  between  the  two  bodies  operating  at  a 
^iftance  from  the  place  of  contaft.  It  fccms  to  be  a  flriking  refult  ef  the  Count's  reafon^ 
ing,  that  if  no  otlier  caufes  fhould  interfere  but  thoie  which  flow  from  the  mutual  combina- 
tion of  the  two  fubftances,  the  fait  would  not,  at  lealt  in  any  moderate  portion  ot  time,  be 
carried  to  the  upper  part  of  the  fluid  relling  upon  it.  He  made  this  the  fubjedt  of  a  par- 
ticular experiment. 

A  cyjin- 


On  Chemical  Solution.     Congelation.  iSj 

.  A  cylindrical  glafs  jar  4|  inches  in  diameter,  and  7A  inches  high,  was  placed  in  the  middle 
^another  cyliaJrical  glafs  jar  7?  inches  in  diameter,  and  eight  inches  hig.h,  which  flood  in  a 
{hallow  earthen  dilh,  nearly  filled  with  pounded  ice  and  water.  This  apparatus  was  placed 
in  an  uninhal'ited  room,  where  the  temperature  was  conftantly  at  about  36  degrees  of  Fahren- 
heit. In  this  fituation,  a  quantity  of  pure  ice-cold  water,  flightly  tinged  with  turnfoi,  was 
poured  into  the  inner  jar,  to  the  height  of  more  than  two  inches;  and  then  by  means  of  a 
glafs  funnel,  which  ended  in  a  long  narrow  tube,  by  introducing  this  tube  into  the  frefh 
water,  and  refting  it  on  the  bottom  of  the  jar,  a  quantity  of  the  ftrongeft  clear  ice-cold  brine 
of  common  fait,  equal  to  that  of  the  frefh  water,  was  poured  very  flowiy  in.  The  ditFerenoc 
of  colour  rendered  the  two  fluids  very  diftinguifliable,  and  fhev^ed  that  they  were  nordif- 
pofed  to  mix  together. 

The  ipace  between  the  two  jars  was  then  filled  with  large  fragments  of  ice  and  ice-cold 
water,  btcaufe  pounded  ice  would  have  obftruiled  the  vi$w;  and  wliea  this  was  done,  the 
tinged  water  of  the  interior  jar  was  carefully  covered  with  ice-cold  olive  oil  to  the  height  of 
about  an  inch.  This  laft  fluid  ferved  to  prevent  the  water  from  being  agitated  by  the  air^ 
or  cooled  by  evaporation  or  the  communication  of  heat. 

The  fluids  remained  in  perfect  tranquillity,  without  the  fmalleft  difpofition  to  mix  together, 
during  four  days.  At  the  end  of  that  time  the  fmalleft  jar  was  removed  without  agitation, 
and  placed  in  the  window  of  a  room  heated  by  a  German  ftove.  In  lefs  than  an  hour  it  was 
perceived  that  the  brine  and  the  tinged  frefh  water  began  to  mix,  and  at  the  end  of  24  hours 
they  were  intimately  mixed  throughout. 

The  author  leaves  philofophers  to  deduce  their  own  concluftons  from  this  experiment; 
but  in  the  mean  time  points  out  a  refult,  which  is  not  only  curious  in  itfelf  but  capable  of 
affording  important  confequences.  He  thinks  there  arc  ftrong  reafons  to  conclude,  that 
were  a  lake  but  very  deep,  its  waters  near  the  furface  would  necefliirily  be  frelb,  even  though 
its  bottom  fhould  be  one  folid  mafs  of  rock-falt.  He  fuggefts  the  advantage  which  might 
accrue  to  an  inland  country  where  fait  is  fcarce,  if  on  experiment  it  ftiould  be  found  that  the 
water  at  the  bottom  of  fome  deep  lakes  is  fait.  And. that  the  water  at  the  bottom  of  all  very 
deep  lakes  ought  neceflarily  to  be  fait,  even  in  fituations  where  no  mines  of  fait  exift,  ap- 
pears to  him  probable,  from  the  geological  fadls  which  indicate  that  moft  of  our  continents 
have  been  covered  by  the  waters  of  the  ocean.  If  ever  that  event  happened,  he  thinks  it 
highly  probable,  that  the  fait  water  left  at  the  bottoms  of  all  deep  lakes  by  the  fea,  on  its 
retiring,  muft  be  there  now. 

Chai'.  II.  In  the  former  part  of  this  EflTay,  the  author  has  availed  himfelf  of  all  the  cir» 
cumllances  which  accompany  the  cooling  and  congelation  of  water,  to  account  for  the 
ftriking  efFe£ls  which  they  produce  in  the  economy  of  heat  on  the  furface  of  the  globe.  As 
water  contra£ls  by  cooling  to  the  41ft  degree,  and  afterwards  expands  until  it  afl\imes  the 
folid  ilate ;  it  fliould  feem  at  firfl  confideration,  that,  when  the  heat  is  abflrrailed  from  the 
bottom  of  a  veffel  containing  this  fluid,  the  particles  of  water  would  rife  and  elude  the  re- 
frigerating power  until  the  whole  mafs  was  cooled  to  that  temperature,  and  afterwards  con- 
tinue to  circulate  in  the  fame  manner  as  if  the  temperature  were  aftually  rifing,  until  at 
length  the  whole  mafs  having  arrived  at  the  temperature  of  32°,  it  would  become  folid  almpfl: 
infta'ntaneoufly.  But  thefe  inferences  fuppofe  the  particles  to  circulate  with  lefs  impediment 
from  inertia  and  refiftance  than  would  be  fufScient  to  detain  them  long  enough  at  the  lower 

.  Y  a  furface 


^^4  Congehtton  at  tht  Hotiom  tf  Waitr.'-Grovni  leh 

ftirface  to  cffecl  their  congelation.  Whether  this  fyppofition  may  agree  with  the  affuaJ' 
ftate  of  things  or  not,  might  perhaps  be  afcertained  by  reafoning  from  former  fa£ls ;  but  in  alli 
fuch  quefHons  where  tbedecifion  can  be  immediately  and  fimply  haci  from  experiment,  it. is 
certainly  bed  to  apply  to  that  fource  of  information.  Coimt  Rumford  made  the  trial,  by 
pouring  mercury  into  a  glafs  tumbler  to  the  depth  of  one  incbj  and  upon  this  about  the  fame 
bulk  of  water.  Both  fluids  were  at  the  temperature  of  60  degrees.  The  tumbler  was  then 
placed  in  a  freezing  mixture  of  fnow  and  common  fair,  which  reached  no  higher  than  the 
upper  furface  of  the  mercury.  The  ice  was  formed  at  the  bottom  in  contact  with  the  mer- 
cury, not  only  under  thefe  circumftances,  butalfo  when  the  experiment  was  varied  by  pre- 
vioully  cooling  the  mercury  to  about  ten  degrees,  and  then  gently  pouring  boiling  hot  water 
on  its  furface.  This  laft  fluid  was  inftantly  frozen,  and  gradually  formed  a  thick  cake  of, 
ice,  covering  the  mercury,  though  almofl  the  whole  of  the  mafs  of  the  unfrozen  water  which; 
rcfted  on  this  ice  remained  nearly  boiling  hot. 

Among  the  inferences  deduced  from  this  experiment,  Count  Rumford  makes  one,  to  ac- 
count for  the  formation  of  ice  at  the  bottom  of  rivers,  which  he  thinks  can  only  take  place 
in  fuch  ftreams  as  do  not  conftantly  fill  their  bed,  but  occafionally  overflow  portions  of 
ground  cooled  by  the  atmofphere  below  the  freezing  point*.      Another  important  inference  ' 
from  the  fame  fcfts  is,  that  it  is  impoflible  any  fluid  fliould  be  of  the  fame  temperature  while 
expofed  to  light,  though  its  mafs  be  everfo  fmall,  and  that  atthediflerence  of  heat  muft  occa-. 
fion  perpetual  motions  among  its  parts..    This  confequence  is  very  fully  explained  in  detail  by 
our  author,  who  confiders  fluidity  as  the  life  of  inanimate  bodies,  and  congelation  as  the 
lleep  of  death  ;  and  is  thence  difpofed  to  reje£t  altogether  the  attribution  of  attractive  powers 
or  exertions  of  any  kind  to  dead  motionlefs  matter.     He  extendshis  meditations  to  the  vital 
principle  in  living  animals,  and  demands  whether  their  life  alfo  do  not  depend  on  the  internal 
motions  in  their  fluids  occafioned  by  an  unequal  diltribution  of  heat  ?   and  whether  {Emula- 
tion be  not  in  alb  cafes  the  mere  mechanical  efFcdl  of  the  communication  of  heat  ? — The  an- 
cient hypothecs,   that  the  life  of  an  animal  reGdes  in  its  blood  ;  the  evident  teadency  of  re- 
^iration,  digeftion,,  and  infenfible  perfpiration  to  produce  and  perpetuate  inequalities  of  tem-- 

*  I  am  not  acquainted  with  th'"  peculiar  circumftances  under  which  ground  ice  is  formed ;.  but  it  is  certain- 
1/  poflible  that  fuch  an  event  (hould  happen  in  a  ftream  which  conftantly  filli  its  banks.  Snppofc  a  ftream  to 
flow  with  very  little  agitation  in  contaft  with  an  atmofphere  eight  degrees  or  more  beneath  the  freezing  point. 
It  is  known  that  water  whofe  parts  are  relatiTely  at  reft,  or  nearly  fo,  may  be  xoolcd  about  eight  degrees  below  3i»' 
without  affuming  the  folid  ftate.  The  middle  of  our  ftream  might  therefore  continue  fluid  when  fo  cooled, 
and  the  congelation  would  only  take  place  at  the  fides,  where  the  friflion  againft  the  banks  would  caufe  the 
rcquifite  internal  agitation.  The  middle  cold  ftream,  on  account  of  its  expaafion  beneath  41  degrees,  wouM^ 
occupy  the  furface,  and  confequently  could  not  rub  againft  the  bottonv  except  in  fliallow  places,  or  unlefs  fome 
means  were  to  offer  of  fuiking  it.  Suppofe  one  or  more  fprings  rifing  from  a  great  depth  in  the  earth,  and, 
thence  poffelfing  the  mean  temperature  of  the  climate,  to  flow  into  the  principal  ftream.  This  mafs  of  warm 
water  would  occupy  the  fuperior  part  of  the  ftream,  and  caufe  the  cold  mafs  to  defcend;  and  wherever  this 
touched  the-bottom  it  would  be  agitated,  and  form  a  coat  of  ice.  Thefe  effefts  would  be  governed  by  the 
temperatures,  the  maflfes,  and  the  local  requifites,  for  which  upon  the  whole  we  are  in  want  of  obfcrvations.  A»- 
10  the  aflTumed  fafls,  they  are  undoubtedly  poffible.  A  remarkable  inftance  of  a  warm  ftream  in  winter  it  feen  ^ 
in  the  fmall  river  Wandle,  which  burfts  out  of  the  earth  near  Carftalton  in  Surrey,  and  after  flowing  with  con- 
fderable  velocity  over  a  line  of  ten  miles,  and  giving  aftivity  to  thirteen  mills,  falls  into  the  river  Thames  at. 
Wandlworth  wifhoHt  having  had  time  to  acquire  the  freexing  temperature,  even  in  the  fevercft  weather.   N. 

peraturej, 


Inftnft  Ht«t  mi  (Itfeernihlt  by  tit  Stti/h,  Uft*  i<fs 

peraturcj  theefRftsof  heat  an4  cold  introduced  into  the  fyftem  in  liquid  foodj,  with  various 
other  phyfiological  events,  are  adduced  by  our  author  in  fupport  of  the  probability  of  that 
dcj£lrine  which  he  recommends  to  the  attention  of  philpfophers. 

Chap.  III.  In  the  third  chapter,  the  Count  proceeds  to  point  out  a  variety  of  ftrjkiiyg  con- 
fcquences  and  obfervations  which  flow  from  the  imperfe£l  conducing  power  of  fluids.  One 
of  the  inoft  immediate  of  thefe  is  the  very  great  degree  of  heat  which  may  exifl:  at  a  fmall 
diftance  from  other  bodies  intenfely  cold.  Thus  it  is  found  that  ite  evaporates  while  expofed 
to  an  atmofphere  in  which  the  thermometer  ftaads  far  below  32  degrees  ;  an  event  which  he 
rationally  accounts  for,  by  fuppoflng  that  foine  of  the  particles  of  air  which  come  into  con- 
tact with  the  ice  are  fo  hot  as  not  only  to  melt  thofe  particles  of  ice  which  they  happen  to 
touch,  but  alfo  to  reduce  part  of  the  generated  water  to  fteam  before  it  has  time  to  freeze 
again ;  or  otherwife  by  fuppofing.  the  fame  efil-6l  to  be^produced  by  the  intenfe  heat  generated 
from  the  abforptionof  light  by  fmall  projeding  points  of  the  ice.  He  even  thinks  the  metals 
would  evaporate  if  they  were  bad  condu^ors  of  heat,  inftead  of  being  very  good  con- 
duftors  as  in  fa£l;  they  are ;  and  in  proof  of  this  he  urges  the  fad,  that  mercury,  which  from 
its  fluidity  is  what  he  would  call  a  non-condu£lor,  is  known  to  evaporate  by  the  mere  heat  of 
the  atmofphere. 

That  the  rnoft  intenfe  heat  is  often  excited  in  the  midft  of  maffes  of  cold  liquids,  is  not  to 
be  doubted.  The  fun's  rays  generate  heat  of  extreme  intenfity  ;  but  when  circumftances  are 
not  favourable  to  its  accumulation  it  is  foon  difperfed,  and  leaves  no  traces  of  its  exiftencc- 
which  can  be  meafured  either  by  inftruments  or  the  organs  of  fenfe.  Ths  Count  does  not 
think  it  improper  to  infer,  that  the  heat  excited  by  a  ray  of  light  in  an  indefinitely  fmall  par- 
ticle of  folid  and  opaque  matter  floating  in  a  mafs  of  cold  water,  may  be  equally  intenfe  with 
that  which  is  generated  in  the  focus  of  the  mofl  powerful  burning  mirror  or  lens.  Hence 
he  accounts  for  various  efFedts  of  the  fun's  lights  which  gradually  produce  changes  of  the 
fame  nature  as  thofe  which  arife  from  very  elevated  temperatures.  Thus  wood.is  rendered 
brown  or  fuperficially  charred,  luna  cornea  is  ren'dereJ  black,  or  as  may  be  fuppofed  fuperfi— 
cially  reduced,  metallic  oxyds  are  deprived  of  oxygen,  the  green  leaves  of  vegetables  emit 
the  fame  fluid,  &c. 

Among  other  familiar  inftances  of,  intenfe  heat,  in  circumftaiKes  where  no  vifible  figns^ 
appear,  the  Count  adduces  that  of  the  afcending  current  of  air  from  a  candle.     Iron  is  fully 
red  hot  at  the  temperature  of  about  iooa°  of  Fahrenheit's  fcale  ;  brafs  melts  at  3807°,  copper 
at  4587°,  filver  at  47 17°,  and  gold  at  5237*;  and  itmuft  be  obvious  that  this  laft:  temperature: 
obtains  where  gold  undergoes  fuilon.     But  fine  gold,  filver,  or  copper  wire  flatted,  fuch  as  is 
ufed  to  cover  thread  to  make  lace,  melts  inftantly  on  being  held  in  the  flame  of  a  candle,  or 
even  if  held  for  a  few  feconds  over  the  flame  at  the  diftance  of  an  inch,  where  there  is  no- 
appearance  of  fire  or  ignition.     The  air,  or  many  of  its  particles,  mufl  therefore  be  heated 
to  this  intenfity,  though  thfir  number  may  be  infufEcient  to  caufe  any  very  elevated  degree 
cf  temperature  in  a  large  mafs  of  metal  or  a  thermometer. 

From  this  hypothefis  of  intenfe  heat  in  the  fmall  parts  of  fluids,  or  bodies  fufpended  in  them 
it  will  follow  that  chemical  foluttons  and  precipitations  are  or  may  be  effected  by  the  fole 
agency  of  heat,  and  will  not  differ  from  fufion  and  congelation  j — that  the  points  of  tempe- 
rature at  whicli  bodies  aflume  the  folid,   the  fliid  and  the  gafcous  ftates  will  be  of  the  utmoft. 
<Bonfe<iuence  with  regard  to  thefe  events,,  and  that  perhaps  there  may  be  no  other  eflTcntial-, 

difiercnce 


rt<f  MtfceUaneous  Experiments  on  Heat. 

difference  between  one  bod»  and  another  but  what  arifes  from  this  circumllance ; — that 
thcfe  points  being  changeable  by  combination,  give  rife  to  a  prodigious  number  of  confc- 
quences  different  from  thofe  which  obtain  in  the  fimpler  eleinents.  We  muft  refer  to  the 
o'riginal  Effay  for  the  more  ample  elucidation  of  thefe  points,  where  chemical  philofophers 
will  fee  the  outline  traced  of  an  immenfe  field  of  rcfearch,  which,  if  it  fhould  not  inf.lLiJe  the 
whole  of  the  phenomena  which  have  been  dellgnated  under  the  name  of  eledtive  attraclion, 
^ill  certainly  comprehend  a  large  mafs  of  effc£ts  which  never  fail  to  prefent  themfelves  in 
every  natural  change  which  comes  under  our  notice. 

Chap.  IV.  The  laft  and  concluding  chapter  contains  a  variety  of  mifcellaneous  experi- 
ments. I.  If  a  thermometer  with  a  long  cylindrical  bulb  being  at  the  temperature  of  the  air 
in  fummer,  or  any  temperature  above  the  freezing  point,  be  pl^unged  to  half  the  length  of  its 
bulb  in  ice  and  water,  the  mercury  will  fal;  in  the  tube  only  half  as  much  as  if  the  whole 
bulb  had  been  immerfcd.  This  experiment  fucceeds  equally  well,  when  the  fuperior  half  of 
the  bulb  is  covered  with  a  flieath  lined  with  foft  fur  to  prevent  the  communication  of  heat 
from  the  air  during  the  experiment.  It  (hews  that  the  upper  half  of  the  mercury  is  not 
coole"d,  or,  in  other  words,  that  heat  does  not  pafs  downwards  in  fluids. — 2.  Ice-cold  water 
{landing  on  ice  at  the  bottom  of  a  thin  tube  of  glafs,  may  be  boiled  by  hoidmg  the  tube  in- 
clined over  the  flame  of  a  candle  applied  near  the  upper  end,  and  gradually  removed  lower 
<lown  as  the  ebullition  proceeds.  In  this  way  all  the  water  in  the  tube  may  be  brought  into 
the  moft  violent  ebullition,  to  within  a  quarter  of  an  inch  of  the  ice,  before  this  begins  to 
■  te  melted. — 3.  The  radiant  heat  from  a  red  hot  iron  bullet  w;is  not  found  to  make  its  way 
downwards  through  liquid  water,  nor  through  mehed  tallow,  nor  melted  wax.  The  experi- 
rrient  was  tried  on  a  thermometer  about  a  quarter  of  an  inch  beneath  the  furface  of  each  of 
thefe  fluids.  Thefe  fa6ls  are  analogous  to  the  obfervation  of  Scheeie,  who  found  that 
radiant  heat  does  not  pafs  through  glafs.  When  the  red-hot  ball  was  held  over  a  cake  of 
ice,  the  heat  appeared  to  be  tranfmitted  by  communication,  though  very  flowly.  The 
excavation- ui.  ice  was  deepeft  near  the  middle.  The  contrary  was  the  cafe  both  in  tallow 
and  in  wax.  Count  Rumford  does  not  direftly  explain  the  caufe  of  this  remarkable  differ- 
ence. It  is  the  only  immediate  faft  I  recolleft  having  feen  in  his  Effays,  in  proof  of  the  affer- 
tibn  that  water  (lands  alone,  with  regard  to  the  property  of  expanding  in  the  lower  degrees 
•of  refrigeration;  and  confequently  of  contracting  as  its  temperature  increafes  in  that  part 
of  the  fcale.  From  this  property  it  would  follow,  that  a  warm  ftream  of  water  muft  de- 
fccnd  immediately  beneath  the  bullet,  while  an  afcending  current  obtains  near  the  circumfer- 
ence of  the  cavity.  But  if  the  expanfion  of  tallow  be  uniform  from  the  earlieft  point  of 
fufion,  the  heated  fluid  will  not  defcend,  but  will  fpread  out  Tideways,  and  circulate  in  a  con- 
trary diretSlion  to  the  current  in  water  ;  while  the  afcending  ftream  of  cold  fluid  will  be 
near  the  centre,  and  will  defend  part  of  the  tallow  in  that  region  from  being  fufed.— 
4i, Beautiful  cryftals  of  fea  fait  were  formed  in  brine  ftand^ng  on  mercury  in  an  open  veflel 
for  half  a  year.  The  Count  makes  it  a  queftion,  whether  the  mercury  contributed  in  any 
manner  to  this  effe/i?  It  feems  probable  that  it  did  not,  and  that  evaporation  equally  flow 

and  undifturbed  would  have  affvirded  the  fame  refult  in  other  circumftances e.  A  fimilar 

remark  may  be  made  on  his  obfervation  of  olive  oil  rendered  colourlefs  by  expofure  to  the  air 
for  fix  months  upon  brine,  in  a  place  where  the  fun's  rays  never  enfc  ed.  ]  he  fame  effc(5l  bap. 
pens  to  dlive  oil  which  remains  in  unclofed  veflels  in  work-(hops.-- 6.  Part  of  the  laft-men- 

D  tioneil 


Circulation  of  a  Fluid  refinibling  ff^inJ/,  jtj 

-ttoned  cotourlefs  oil  Being  imperfedly  congealed,  an  attempt  was  made  to  caufe  radiant  heat 
to  defcend  through  its  mafs.  It  was  expefted  that  the  tranfparent  or  nrelted  portion  of  the 
oil  would  in  this  cafe  have  been  hemifpherical,  or  at  ieaft  of  fome  convex  figure  ;  but  this  did 
not  happen,  for  the  furface  beneath  the  fluid  or  mel;ed  part  continued  flat.  Whence  the 
Count  infers,  that  the  fufion  was  eftefted  merely  by  the  heat  abforbed  or  generated  by  the 
fides  of  the  tumbler. 

7.  The  concluding  experiment  of  this  ElTay  affords  a  ftriking  rcfult  of  the  circulation  oif  ' 
fluids  under  difierent  circumftanres.    When  the  inflrument  dcfcribtd  in  our  Journal,  I.  342, 
was  placed  by  accident  in  the  window  of  a  ruom  warmed  by  a  German  ftove,  the  difference  ■ 
of  temperature,  on  the  fide  neareft  the  window  from  that  oppofite  the  internal  part  of  the 
room,  was  fuch  as  to  keep  up  a  conftant  circulaticm  of  the  fluid.     This  event  induced  the 
Count  to  fubifitute  a  box  of  plate  glafs  in  the  place  of  one  of  the  panes  of  his  window.  This 
apparatus,  which  was  13  inches  high,   10'-  inches  wide,  and  one  inch  wichin  from  plate  to 
plate,  was  half  filled   (and  as  I  ibppofe  afterwards  completely  filled)  with  the  faline  folution. 
with  pieces  of  amlcr  floating  in  it,  r.s  dcfcribed  at  the  place  laft  quoted.     The  Count  ex- 
pelled to  behold  the  currents  as  ufual  in    this  new  vefl'el  ;  but  to  his  great  furprife  they 
proved  not  vercical,  but  horizontal,  exhibiting  a<5lual  winds  in  oppofite  directions,  which 
fpringing  up  in  the  d,fRrent    regions  of  thia  artificial  atmofphere,  prevailed  for   a  long 
time  with  the  utmoft  regularity,  while  the  fmall  particles  of  the  amber   colle^ing  them- 
felves  together  formed  clouds  of  the  moft  fantaftic  forms^  which,  being  carried  by  the  winds 
rendered  the  fcene  perfectly  fafcinating. 

Several  fubordinate  circumflances  gave  thefe  motions  a  more  intimate  refemblancc  to 
the  atmofpherical  phenomena.  One  remarkable  appearance  never  failed  to  prefent  itfelf 
regularly  every  day  during  the  three  weeks  that  the  experiment  was  continued.  The  cloudsj 
after  having  been  driven  about  all  day  by  the  different  currents,  in  the  liquid  (of  which  there 
were  fimetimes  as  many  as  fix  or  feven  running  in  oppofite  dire£tions  at  the  fame  time), 
never  failed  to  colle£l  themfelves  together  in  the  evening  into  large  mafTes,  fometimes  form- 
ing only  oncy  and  fometimes  two  or  three  ftrata  at  different  heights,  where  they  remained, 
to  all  appearance  perfectly  motionlefs  during  the  night. 

The  experiment  was  put  an  end  to  by  the  accidental  breaking  of  the  veffel. 


VI. 

^n  Account  of  certain  Motions  which  fmall  lighted  Wicks  acquire  when  fwimming  in  a  Bafon  of 
Oil;  together  with  Objervations  upon  the  Phenomena  tending  to  explain  the  Principles  upon 
which  fuch  Motions  depend.  By  PATRICK  WlLSON-,  F.R.S.  Edin,,  and  Profejfor  of 
pra£lical  jijironomy  in  the  Univerfity  of  GLtfgo-ut  *. 

DE4K  SIR,  Glafgow  College y  Jpril  28,  1 795; 

Jl  now  fit  down  to  give  you  fome  account  of  the  little  hydroftatical  lamp  which  I  fo- 
briefly  mentioned  to  you  in  a  former  letter.     As  I  am  far  from  being  fure  whether  what  i 

•  In  a  Letter,  to  Mr.  John  Playfair,  F.  R.  S.  Edin.  &c>  infertcd  in  the  Edinburgh  Tranfaftiont,  vol.  iv. 


*68  Account  of  a  /elf-moving  Lamp. 

•have  to  offer  upon  this  fubjefl  may  be  entitled  to  the  notice  of  the  Edinburgh  Royal  Scv 
ciety,  fo  I  will  refer  this  point  to  your  determination  after  you  have  had  leifure  to  confider 
the  contents. 

The  phenomena  treated  of  in  the  feqael  were  quite  new  to  me  a  few  months  ago,  and,  fo 
iar  as  I  know,  have  not  hitherto  been  attended  to  or  dcfcribed  by  any  body  elfe.  What  I 
•have  called  the  hydroftatical  lamp,  confifts  of  a  fmall  circular  patch  of  common  writing 
.paper,  about  tliree-eighths  of  an  inch  in  diameter,  having  about  a  quarter  of  an  inch  of  foft 
^cotton  thread  {landing  up  through  a  puncture  in  the  middle  to  ferve  as  a  wick ;  and  the  phe- 
nomena inqueftion  are  certain  motions  which  fuch  minikin  lamps  acquire  when  lighted  and 
Tnade  to  fwim  in  very  pure  fallad  oil. 

A  (hallow  glafs  bafon,  with  fides  rifing  nearly  perpendicular,  or  a  common  glafs  falver, 
will  conveniently  contain  the  oil  for  thefe  experiment?.  As  foon  as  the  lamp  is  lighted,  it 
will  immediately  fail  brilkly  forward  in  fome  direction  till  it  meets  the  fide  of  the  vefiel,  and 
afterwards  will  take  a  circular  co'urfe,  always  bearing  up  to  the  fides,  and  fo  will  perform 
many  revolutions. 

Sometimes  the  circulation  is  from  right  to  left,  and  fometimes  in  the  contrary  dire£iion, 
according  as  that  point  of  the  paper  bafe,  which  in  the  diredt  failing  kept  always  foremoft, 
■turns  away  from  the  fide  of  the  glafs,  a  little  to  the  right  or  to  the  left  hand  of  that  which 
comes  to  be  the  point  of  coiitadl.  This  turning  away  of  what  may  be  called  the  lead- 
ing poiflt  of  the  bafe  is  diftin6lly  obfervable  by  a  partial  rotation  of  the  lamp  round  the 
wick  as  an  axis,  as  foon  as  it  arrives  at  the  fide  of  the  vefiel.  Sometimes,  though  rarely, 
the  leading  point  itfclf  attaches  itfelf  to  the  fide,  and  forms  the  vinculum,  in  confequence  of 
the  well-known  corpufcularattraftion  between  the  elevation  of  oil  around  the  bafe  and  that 
belonging  to  the  fides  of  the  glafs;  and  when  the  vinculum  fo  correfponds  to  the  leading 
point,  the  lamp  will  be  found  to  fland  dill  without  any  tendency  to  circulate. 

When  the  little  witk  has  any  fenfible  eccentricity  upon  the  circular  paper  bafe,  the  lamp 
will  fail  fo  as  to  make  that  part  of  the  bafe  which  lies  neareft  to  the  wick  the  ftern  ;  and  if 
the  bafe  of  the  lamp  be  clipped  to  an  oval  form,  and  the  wick  placed  in  the  longer  axis  ex- 
centrical,  that  end  of  the  bafe  neareft  the  wick  will  alfo  keep  hindermoft,  when  the  lamp 
fails  icrofs  the  falver.  In  the  fame  manner,  if  there  be  an  equilateral  triangle,  having  its 
wick  in  the  perpendicular  which  bifedls  any  of  the  fides,  either  the  vertex  or  fide  will  be- 
come the  ftern,  and  keep  hindermofl-,  according  as  the  wick  is  placed  neareft  the  one  or  the 
Other.  Lamps  fo  conftrudled  are  found  alfo  to  circulate  upon  their  arrival  at  the  fide  of  the 
veflel,  when  the  leading  point  turns  away  from  the  glafs,  as  it  commonly  happens. 

Whatever  be  the  caufe  of  the  failing  of  the  lamp  diredlty  forward,  the  perpetual  circu- 
lation after  it  arrives  at  the  fide  feems  to  proceed  from  the  force  which  formerly  impelled 
jt  fiill  ading  in  the  fame  manner,  but  in  a  direction  inclined  to  that  of  the  corpufcular  at- 
traction which  forms  the  vinculum  ;  and  it  is  evident  that  this  inclination  will  be  greater  or 
lefs  according  as  the  leading  point  is  more  or  lefs  averted  from  the  glafs.  When  it  fo  hap- 
pens that  the  leading  point  and  vinculum  coincide,  it  (hould  feem  that  both  forces  juft  now 
mentioned  muft  urge  the  lamp  in  a  direction  perpendicular  to  the  fide  of  the  glafs ;  in  which 
cafe  it  muft  ftand  ftill,  agreeable  to  obfervation. 

The  next  thing  which  I  had  occafion  to  take  notice  of  when  the  lamp  failed  in  a  direcfl 
courfe,  was  a  fcemingly  very  adlive  repulfion  between  its  ftern  and  the  oil  at  the  furface  con-  I 

tiguoas 


Piiaciple  of  Motion  in  a  jioating  Lamp.  l6g 

-tiguous  to  it.  This  became  manifeft  when  very  fine  charcoal  dull  was  lightly  fcattered 
around  the  lamp.  As  it  then  prcceeded  in  its  courfe,  it  marked  out  a  fpreading  or  diverg- 
ing vjake  behind  it  entirely  clear  of  all  dull,  in  coniequence  of  the  particles  being  chafed 
backwards  and  laterally  with  a  motion  mucn  more  than  merely  relative. 

Defirous  of  learning  how  this  difpofition  ot  the  duft  would  take  phce  when  the  lamp 
was  ftationary,  I  conftrnfted  one  of  a  fine  wafer,  and  with  an  excentric  wick  confifting  of 
a  foft  cotton  thread  doubled  ;  and  to  prevent  the  wafer  or  baL'  from  catching  fire  I  coated 
its  upper  furface  with  gold  leaf.  When  this  was  made  to  reft  immoveably  upon  the  oil,  the 
dufl  retired  in  all  direftions  fo  as  to  leave  the  fpace  adj.-.cent  to  the  wafer  quite  free  from 
every  particle.  But  here  it  was  obfervable,  that  this  difperfion  of  the  duft,  by  the  feeming  re- 
pulfionof  the  bafe  of  the  lamp,  was  much  more  rapid  at  that  fide  which  lay  nearefl  to  the 
wick  than  at  any  other  part,  and  lead  of  all  fenfible  at  the  fide  diametrically  oppofite. 

Tiie  circumftances  laft  menticned  feem  fufficiently  t  >  account  both  for  the  progrelTive 
motion  of  the  lamp,  and  for  the  general  law  of  this  motion  formerly  defcribed.  For,  re- 
garding this  difperhon  of  the  duft  as  yet  only  in  a  general  way,  and  as  theeffc£l  of  fome  re- 
pulfion  between  the  bafe  and  the  oil  contiguous  to  it,  the  fadts  above -inentioned  plainly  in- 
dicate, that  in  ail  cafes  this  repulfion  is  ftrongeft  at  that  part  of  the  bafe  neareft  the  wick  or 
flame  ;  and  as  a£lion  and  readtion  are  equal  and  contrary,  the  lamp  muft  theiefore  be  im- 
pelled, in  the  direflion  of  a  line  drawn  through  the  wick,  towards  that  part  of  the  bafe  moft 
remote  from  it,  and  where  the  readtion  is  the  leaft. 

But  in  order  to  obtain  a  ftill  more  competent  knowledge  of  the  phyfical  catife  of  thefe  mo- 
tions, it  feemed  now  neceflary  to  enquire  more  particularly  into  this  apparent  repulfion, 
between  the  bafe  of  the  lamp  and  the  furrounding  oil,  as  indicated  by  the  difperfion  of  the 
<3uft  in  the  manner  above  defcribed  :  and  here  the  following  confiderations  prefented  them- 
felves  : 

/  rThe  oil  in  the  bafon,  when  of  an  uniform  temperature,  has  all  its  parts  in  a  ftate  of  equi- 
librium and  of  reft.    When  the  lamp  is  lighted,  it  is  evident  we  have  a  very  aflive  caufe  in- 
troduced tending  to  deftroy  that  equilibrium.     This  caufe  is  the  flame  which  broods  over 
a  fmall  portion  of  the  oil,  and  is  feparated  from  it  only  by  the  intervention  of  a   piece  of 
paper  or  a  wafer.  The  oil  in  fiich  circumftances,  in  confequence  of  being  violently  heated, 
muft  fuddenly  increafe  in  volume,  and  muft  now,  on  account  of  the  decreafe  of  its  fpi-cific 
gravity,  be  prefTed  upwards  by  a  force  fufficient  to  raife  part  of  it  above  the  general  level. 
But  this  heated  portion  of  oil,  in  its  endeavour  to  rife  up,  will  meet  with  a  refiftance  equal  to 
the  weight  of  the  incumbent  lamp,  which  will  determine  it,  in  feeking  a  vent,  to  Aide  out 
from  under  the  bafe  in  a  thin  fuperficial  ftream  ;  and  it  feems  to  follow  with  equal  certainty, 
that  this  conftant  ftream  will  flow  moft  rapidly  and  moft  copioufly  towards  that  fide  of  the 
bafe  of  the  lamp  where  the  refiftance  is  leaft,  or  where  it  has  the  fhorteft  way  to  prefs  for- 
ward ;  that  is,  from  under  the  wick  or  flame  to  the  edge  of  the  bafe  which  is  the  neareft, 
according  to  what  we  have  f^en  to  be  agreeable  to  the  phenomena.     But,  from  the  laws  of 
motion,  it  is  certain  that  the  re-adlion  of  this  ftream  of  rarefied  oil,  thus  ilTuing  moft  rapidly 
and  moft  copioufly  from  a  particular  fide  of  the  bafe,  muft  impel  the  lamp  in  the  contrary  di- 
re£\:ion,and  make  it  fail  in  the  manner  we  have  feen.     It  may  further  be  remarked,  that  the 
heated  oil  fo  retreating  from  the  flame,  and  endeavouring  to  rife  fomewhat  above  the  general 
level,  in  confequence  of  its  diminifticd  fpecific  gravity  may  more  or  lefs  lift  up  that  fide 
Vol.  II. — July  1798.  Z  of 


.is  blown  out  the  hmp  finks  , to  the  tottom ;  and  even  a  lamp  with  its  bafe 

thin  .lamina  of  talc   feifs  very  welf'tiMthe  flame  iS  extineuifhed,  and  then  it  ii 

>  ,.i   '•'"'•••,'■■   'I.--  -     ■f.-'.      ! -Jifif  .    ..,  .-^Ii  n.,,7'  "^        1'....,...       , 
link'.  .•  ..-.;,.,, 


170  ^ccoitni  of  a  Jilf-iiiowig  Lamp, 

1-  ■'-'■•  -I     '    '     ■  -^  '.  J'  •.:..    .    ■    .'t    ,T.. 

of  the. bafe  neareft  the  wick,  and  aid  tj^e  re-aifilion.of  the  recoiling  dream,  by  making  ttj9 

lamp. fail. in  the  oppofite  direilion,  as  it  were  down  hill. 

That  the  rarefied  oil  linden  the  bafe  has  really  a  conflarit  tendency  to  rife  above  the  ge- 
neral level,  feems  undeniable  from  the  following  faflsV  namely,  that 'after  any  of  the  lamps 
has  burned  a  little  while,  and.  has  got  its  bafe  foaked  witb   the  oil,  as  foon  as  the  flame 

made  of  a 
immediately 

•  Agreeable  to  tne  explanation" .wfiichnas  now i)efett  'ak6mpted,'r  found  that  when  a  to- 
pical heat  was  applied  to  the  iurface  of  the  oil,  by  bi'inging  the  point  of  a  poker  dully  red 
hot  nearly  into  contact,  there  was  foon  produced  a  fuperficial  ftream  or  efflux  from  the  iron 
in  all  directions,  .which  cleared  the  face  of  the  oil  from  the  charcoal  duft  in  a  wider  and  a 
Wider  circle,  tillat'Uft  the  whole  particles  were  crowded  together  at  the  confines  of  the 

bafon.  'V   .  J.  , ,  I,, 

When  the  oil  in' 'tfifs 'experiment  was  (baltow;  having  goM  leaf  beat  into  very  minute- 
parts  mixed  with  it,  an  oppofite  flream  was  obferved  below  fetting  in  towards  the  poker  in 
all  directions,  and  then  rifing  upwards.  But  this  general  tendency  of  all  the  parts  of  the 
fluid,  of  moving  in  (^uefl  of  an  equilibrium,  is  illuflrated  in  a  very  entertaining  manner  as 
follows :  Into  a  tea  cup  or  punch  gL.fs  nearly  filled  with  pure  water,  pour  a  deflcrt  fpoonful 
ofvery.clear  fallad  oil  with.minute  particles  dfgold  leaf  in  it.  If  the  water  be  cold,  the  oil 
when  poured  on  at  the  tenfrc,  leifurely  and  cbntinuedly,  will  reft  upon  the  furface  in  the 
form  of  a  lens,  and  remain  infulated'  and  eq'uidiftant  from'  the  fides  of  the  veflel.  A 
little  lamp,  when  put  upon  this  lens  of  , oil  and  lighted,  will  fail  and  circulate  as  long?r 
ones  do  in  a  bafon.  If  it  be  rK)W  madfe  to  ftand  flill,  it  is  very  amufing  to  obferve  the  mi- 
nute particles  of  the  gold  perpetually  thrown  out  brifkly  at  the  ftern  in  the  fuperficial  cur- 
rent, whilil  the  particles' in  the  fund  of  the  lens  creep  in  all  dire<£lions  towards  the  lamp, 
and  at  laft  rife  up  ufidfei-'tnebafe  towards  the  flame,  as  the  great  centre  of  attraction,  till 
they  are  caught  by  the  retreating  fuperficial  ftream,  in  which  they  rapidly  trend  ofFto  fome 
diHance,  when  again  they  fink  to  renew  the  circulation. 

When  a  patch  of  paper,  or  a  wafer,  or  fuch  light  body,  fwims  upon  the  oil  in  the  bafon, 
the  point  of  a  hot  iron  held  near  to  it  makes  it  flit  its  place,  and  move  away  by  a  feeming 
repulfion  ;  but  in  reality  by  the  heat  generatinga  fuperficial  ftream  flowing  from  the  iron  in 

■  all  direaionsi'"'  '^  '^"'■!',  ^^^  "'."*  ^"  =''^' '  ">'  -•'o^- 

'  Again,if  upon  oil  of  tOrperrtine,  £Ether,  alcohol,  or  any  of  the  inflammable  fluids  polTeif- 
ing  much  tenuity,  you  throw  a  wafer  much  heated,  it  will  immediately  glide  away  and  con- 
tinue in  m'otlon  till  it  cools ;  when  the  ftream  which  ifliied  from  fome  part'  of  it  moft  co- 
'pioufly  teafeS'."    DbiibleVti'ni^Tnelted  tallow,- bees- wax,  and  rofin,  alfo  afford  the  fiime  con- 
'  tinued  efflu5^  at  th6  hrtAce  upon  a  topical  application  of.beat,  and  the  fame  phenomena  as 
the  oil   does  when  little  lamps  are  made  to  fwim  in  them.     It  is  fomewhat  remarkable, 
'however,  that  though  the  inflammable  fluids  all  agree  in  this,  yet  the  topical  application  of 

■  heat  at  the  furface  of  water  does  not  produce  fimilar  effedts. 

For,  if  the  point  of  a  poker  neaily  red  hot  be  held  very  clofc  to  the  furface  of  water  in  a 
bafon,  the  particles  of  the  charcoal  diift  do  not  at  all  glide  away,  as  they  do  in  the  cafe  of  oil, 
biit  feem  to  acquire  only  a  'fldw  irregular  circular  motion,  which  in  time  fpreads  wider, 

■  •  whilft 


Account  of  a felf-tnov'ing  Ldmfi.  1.7 1 

Vphilft  the  floating  niotcf,  or  particles  of  i<i{^^  keep  nearly  their  relative  places  ;  siid  the 
fame  thing  happens,  though  the  point  of  the  iron  touches  the  water  fo  as  to  make  it  fimmer, 

I  do  not  well  know  how  to  account  for  thif,  unlefs  it  may  be  a  confeqiience  of  the  known 
much  k'fs  expanfibility  of  water  by  heat,  compared  to  that  of  the  inflamnnabJe  fluids,  and 
which  may  be  fo  inconfiderable  as  not  to  deftroy  the  equilibrium,  fo  f.ir  as  to  produce  aa 
ciflux  from  the  lighter  and  expanded  fluid  immediately  under  the  jjeatcd  body.  Pofiibly  too 
the  parts  of  the  water,  as  foon  as  heated,  may  tranfmit  the  furplus  temperature  to  the  con- 
tiguous colder  water,  much  more  rapidly  than  the  inffamifiable  flufd?'  do  in  like  circum- 
ftances,  and  thereby  refift  the  high  temperature  neceflary  to  that  degree  of  expanfion 
which  would  difturb  the  equilibrium  and  produce  an  efflux ;  not  to  mention  that  the  max- 
imum of  this  temperature  can  never,  at  any  rate,  exceed  212  degrees,  the  boiling  point  of 
water. 

That  the  equilibrium,  however,  atnongfl  the  parts  of  water  is  difturbed  by  the  local  ap- 
plication of  heat,  though  in  a  much  fmaller  degree  than  what  obtains  among  the  inflam- 
mable fluids,  appears  from  an  experiment  I  was  led  to  make  with  a  fmall  thin  cup  fwim- 
ming  on  water,  and  fo  contrived  as  to  carry  and  feed  with  oil  a  wick  placed  a  little  way 
down  from  the  lip  in  the  infide,  fo  as  to  be  on  a  level  with  the  water.  The  confequence  of 
this  conftruftion  was,  that  the  cup  moved  upon  the  water  very  flowly.but  always  with  the 
flame  evidently  fl:crnmoft.  The  fame  cup,  when  taken  from  the  water  and  put  into  a  bafon 
of  ftrong  rum,  failed  a  great  deal  faflrer,  and  according  to  the  fame  ufual  law. 

I  am  much  afraid  that,  by  this  time,  I  have  wearied  you  by  fuch  a  detail  of  minute  facis 
and  circumftances,  and  by  thofe  frequent  repetitions  which  every  new  fubjed  more  or  lefs 
requires.— And  I  ever  remain,  dear  Sir,  your  moft  obedient  faithful  fervant, 

PAT.    WILSON, 

P.  S.  Should  you  be  inclined  to  repeat  any  of  the  experiments,  the  following  diredions 
and  mifcellaneous  obfervations  may  be  attended  to  :  The  thread  I  made  ufe  of  for  the  wicks 
was  of  that  foftkind  commonly  employed  in  the  flowering  of  muflin.  After  making  the  punc- 
ture in  the  bafe,  you  put  through  a  bit  of  the  thread,  which  clip  fliort  off  below,  and  with  a 
pin  force  in  the  burr  gently  round  the  thread,  to  give  the  bafe  a  proper  hold  of  it,  Thea 
clip  away  the  fuperfluous  thread  above,  leaving  the  wick  about  a  quarter  of  an  inch  long  ; 
and  fo  the  lamp  is  comp'eted.  Set  it  then  upon  the  oil  by  taking  hold  of  the  wick,  that  the 
paper  bafe  may  not  be  bent  or  diftorted  by  handling  it ;  and,  after  the  wick  is  touched  with 
a  drop  of  oil,  it  is  ready  for  being  lighted.  For  this  purpofe  a  bit  of  packthread,  which  has 
been  fteeped  in  oil,  is  a  cleanly  and  convenient  match,  and  fheds  no  impurities  on  the  oil, 
as  a  candle  or  wax  taper  would  do. 

When  you  want  the  lamp  to  circulate,  the  oil  muft  be  very  pure,  and  brought  into  full 
contadt  with  the  fides  of  the  glafs.  The  oil  and  the  bafon,  or  falver,  fbould  all  be  allowed 
to  come  to  the  fame  temperature,  between  55  and  60  degrees  of  Fahrenheit.  For,  if  any 
part  of  the  brim  be  much  hotter  than  the  refl,  the  lamp,  on  arriving  there,  will  leave  the 
fide,  by  the  current  iffuing  from  the  heated  part  forcing  it  away. 

Sometimes  the  lamp,  when  failing,  veers  a  little  into  a  different  diredVion,  by  the  bafe 
altering  or  warping  by  the  fcorching  heat  of  the  flame,  which  determines  the  ftream  to 
flow  out  nioft  copioufly  at  a  different  part  of  the  bafe. 

Z2  In 


-l<ji'  Experiments  an  the  lateral  Communicalm  »f  Motion  in  Fluids, 

In  the  melted  greafe  which  lies  round  the  wick  of  a  common  candle,  when  lighted,  thers 
are  fometimes  obferved  atoms,  which  have  been  left  by  the  fnuffers,  moving  to  and  from  the 
flame  continually.  Thefe  motions  have  been  conceived  by  fome  as  occafioned  by  attrac- 
tions and  repulfions,  in  confequence  of  an  eleiSlrical  quality  imputed  to  the  flame.  It  fhoiilJ 
feem,  however,  that  they  depend  merely  upon  oppofite  currents,  at  the  furface  and  imme- 
diately below  the  furface  of  the  melted  greafe,  according  to  the  principle  above  explained. 


VII. 

Experimental  Refearches  concerning  the  Principle  of  the  lateral  Communication  of  Motion  in 
Fluids,  applied  to  the  Explanation  of  various  Hydraulic  Phenomena.  By  Citizen  J.  B. 
VenTVRI,  Profejfor  of  Experimental  Philofcphy  at  Modena.,  Member  of  the  Italian  Society 
of  the  Injiitute  of  Bologna,  the  Agrarian  Society  of  Turin,  is'c* 

HE  apparatus  made  ufe  of  in  mod  of  the  following  experiments  is  the  fame  as  that  of 
Poleni  t-  It  is  reprefentedatFig.  i.  Pi.  VIII.  The  refervoir  X,  of  a  conical  form, has  forty 
inches  diameter  at  CE,  and  30  at  O  P.  F  P  is  a  broad  plate  of  copper,  the  plane  of  which 
is  perpendicular  to  the  horizon ;  it  is  applied  to  the  infide  of  the  refervoir.  The  valve  or 
flap  rS,  moveable  by  the  handle  K,  is  drawn  up  againfl:  the  fide  of  the  veflel  above  F,  in 
order  that  it  may  not  impede  the  courfe  of  the  particles  of  the  fluid  contained  in  the  refer- 
vo>f  to  the  aperture  P.  I  have  applied  different  ajutages  to  this  aperture,  according  to  the 
exigence  of  the  cafe.  The  tubes  which  I  applied  were  made  of  tinned  iron  of  the  beft 
quality  ;  the  longitudinal  jun£lion  of  the  edges  was  made  by  immediate  contadl,  and  not  by 
overlapping,  and  the  whole  of  the  workmanfhip  was  executed  with  great  care.  When  the 
aperture  was  fimply  a  hole  through  a  thin  plate,  the  thicknefs  of  its  edge  did  not  exceed  one 
fourth  of  a  line. 

The  upper  vefi"el  Z  ferves  to  maintain  the  water  of  the  refervoir  X  at  the  conftant  height 
of  the  line  C  E,  while  it  flows  out  through  P.  The  plug  A  B  is  drawn  more  or  lefs  back, 
in  order  to  regulate  the  introduction  of  the  fupply.  The  box  or  flielf  D  L  prevents  this 
water  from  exciting  by  its  fall  any  agitation  which  might  influence  the  emilTun  at  P.  The 
opening  at  Q.difcharges  the  fuperfluous  water  which  might  rife  above  the  line  C  E.  The 
height  of  the  furface  C  E  above  the  centre  of  the  orifice  at  P  was  32,5  inches,  in  all  cafes 
where  it  is  not  otherwife  exprefled. 

Mod  of  the  expetimcnts  here  defcribed  were  made  in  public  at  the  Philofophical  Theatre 
of  Modena  ;  various  men  of  fcience  were  prefent  at  the  reft  j  the  diflFerent  departments  of 
experiment  were  i>erformed  by  feveral  perfons  at  the  fame  time.  One  of  thefe  operators  re- 
peated the  fcconds  audibly  from  the  clock  ;  another  drew  back  the  valve  S  F;  a  third  regu- 
lated by  the  means  of  the  plug  B  the  introduftion  of  the  fupply  of  water,  fo  that  a  very  thin 

•  Since  the  receipt  of  this  memoir  (which  is  equally  valuable  as  the  fource  of  data  for  fcientific  proceffes, 
and  of  ufcful  praaical  relults,  tiiher  unknown  or  dfreganled  in  hydraolic  works)  it  has  reniained  in  my  hands 
with  the  intention  of  prefcnting  my  readers  with  an  abftraft  of  its  contents.  But,  upon  ftriacr  confideration,. 
1  have  thought  it  beft  to  give  it  entire  from  the  French  original.    N. 

f  De  Caftellis.   This  treatife  is  reprinted  in  the  third  volume  of  Hydraulic  Treaties,  publiflicd  at  Parma.  V, 

6  fheet 


Experiments  on  the  lateral  Commtinkatkn  of  Motion  in  Fluids,  I'j'i 

fheet  of  water  conftantly  flowed  at  Q^  At  the  inftant  agreed  upon,  the  paffages  of  the  water 
were  again  clofed,  Every  experiment  was  repeated  fucceflively  for  a  number  of  times,  until 
the  agreement  of  the  refults  had  removed  every  fufpicion  of  error.  I  am  allured  that  even  in 
the  mod:  complicated  cafes,  the  quantity  of  error  could  not  exceed  one  fortieth  part. 

The  meafures  indicated  in  the  courfe  of  thefe  experiments  were  taken  from  a  toife  adjuft- 
ed  by  that  of  the  Academy,  which  Citizen  Lalaiide  fent  me  in  1783.  Thefe  meafures,  as 
well  as  all  the  others  of  the  i8th  century,  will  undergo  the  fate  which  is  prepared  for  them 
by  the  eftablifhment  of  the  new  metre.  They  may  be  reduced  to  this  new  ftdndard,  by  ob- 
ferving  that  the  foot  is  to  the  metre  as  100  to  308. 

The  wifefl:  philofophers  have  their  doubts  with  regard  to  every  abftraft  theory  concern- 
ing the  jr.otion  of  fluids  ;  and  even  the  greateft  geometers  avow,  that  thefe  methods,  which 
have  afforded  them  fuch  furprifing  advances  in  the  mechanics  of  folid  bodies,  do  not  afford 
any  conclufions  with  regard  to  ''i.'draulics  but  fuch' as  are  too  general  and  uncertain  for  the 
greater  number  of  particular  cafes.  Imprefled  with  a  conviction  of  this  truth,  I  have  attended 
to  theory  only  when  ir  combined  with  the  facfts,  and  was  iieceflary  to  unite  them  under  a  fingle 
point  of  view.  E.'cn  this  fmall  portion  of  theory  may,  if  the  reader  pleafes,  be  rejected) 
and  he  may  confider  the  following  propofitions  fimply  as  the  refults  of  experiment. 

When  I  quote  the  eftimable  work  of  Citizen  BofTut,  on  hydrodynamics,  I  refer  to  the 
edition  of  1786*. 

Propofttion  i.  The  motion  of  a  fluid  is  communicated  to  the  lateral  parts  which  are  at 
reft. 

Newton  has  affirmed,  that  when  motion  is  propagated  in  a  fluid,  and  has  arrived  beyond 
the  aperture  B  C,  fig.  2,  the  motion  diverges  from  that  opening,  as  from  a  centre,  and  is 
propagated  in  right  lines  towards  the  latdVal  parts  N  K,  as  well  as  towards  S.  The  fimple 
and  immediate  application  of  this  theorem  cannot  be  applied  to  a  jet  which  iflues  from  the 
aperture  B  C  at  the  furface  of  rtill  water.  Circumftances  enter  into  this  cafe,  which  tranf-  ' 
form  the  refult  of  the  principle  into  particular  motions.  It  is  neverthelefs  true,  that  the  jet 
BC  communicates  its  motion  to  the  lateral  parts  N  K;  but  it  does  not  repel  them  towards 
Pand  Q_,  but  on  the  contrary  tranfports  them  along  with  its  own  fleam  towards  S. 

Experiment  \.  The  horizontal  cylindric  pipe  AC,  fig.  3,  is  introduced  into  the  vefTel 
DEFB,  which  is  filled  with  water  as  high  as  DB.  .Oppofite  and  at  a  fmall  interval  from 
the  aperture  C  commences  a  fmall  reftangular  channel  of  tinned  iron,  SMBR,  which  is 
open  at  top  S  R ;  the  inclined  bottom  M  B  refts  on  the  edge  of  the  veffel  B.  It  is  24  lines 
broad;  the  diameter  of  the  tube  AC  is  14,5  lines;  the  extremity  A  is  applied  to  the 
aperture  P  of  fig.  i.  The  water  of  the  refervoir  being  fuffered  to  flow  through  the  tube 
AC,  the  jet  rifes  along  the  fmall  channel  MB,  and  flies  out  of  the  vefTel  in  the  ftream  B  V, 
By  this  means  a  current  is  produced  in  the  fluid  of  the  vefTel  DEFB;  this  fluid  enters  into 
the  channel  S  R,  and  iflues  by  MBV  along  with  the  jet  AC,  fo  that-in  a  few  feconds  the 
water  D  B  falls  to  M  H. 

*  I  confider  this  treatife  as  fuperior  to  all  which  before  were  extant.  It  is  founded  on  a  combination  of  the 
principles  of  experiment  and  of  theory.  I  have  prohted  by  thefe  principles,  and  feveral  particular  remarks 
which  the  fame  Citizen  BoiTut  and  Citizen  Prony  have  been  fQ  good  as  to  comm.utucate  after  perufal  of  my 
memoir,    V. 

Experimtnf 


174  Exj'eii'iuHtj  on  the  laleral  Cotninunicathn  of  Alotlcn  In  Fluids. 

EKpetimeiit  2.  Bring  fome  very  light  or  moveable  bodies  near  the  jet  of  w^ter  P  Y,  fig.  T, 
which  ifTuts  from  the  aperture  P,  and  falls  from  a  certain  height  E  into  the  inferior  vefl'el 
RT.  It  is  feen  that  thcfs  bodies  are  carried,  along  by  the  air  which  defcends  with  the  jet 
P  Y.     Purt  of  this  air  is  carried  along  and  plunged  into  the  water  of  the  inferior  veffel. 

Thefe  experiments  clearly  prove,  that  the  fluid  which  ifi'ues  by  B  C,  fig.  2,  imprelTes  its 
motion  on  the  lateral  parts  N  K  ;  net  by  impelling  them  towards  P  Q^,  but  by  carrying  them 
along  with  itfelf  towards  S.  1  call  this  the  lateral  communication  of  motion  in  fluids. 
Newton  was  acquainted  with  this  communication,  and  has  deduced  from  it  the  propagation 
of  rotatory  motion  from  the  interior  to  (he  exterior  ftrata  of  a  whirlpool.  Is  this  lateral 
communication  of  motion  occafioned  by  the  vifcidity  or  mutual  adhefion  of  the  parts  of  the 
fluid,  or  their  mutual  engagement  or  intermixture,  or  the  divergency  of  thofe  parts  which  are 
in  motion  ?  We  may  perhaps  be  able  to  give  fome  account  of  this  v/hen  we  (hall  have  ken 
the  cffl6ls;  but  in  the  mean  time,  whatever  may  be  the  caufe,  let  us  take  the  eS^Q.  as  ex- 
perience points  it  out;  let  us  confider  it  as  a  principle,  and  endeavour  to  apply  it  to  fome 
particular  cafes  in  order  to  afcertain  the  refult. 

The  firft  circumftance  to  which  I  propofe  to  apply  this  principle  is  the  increafe  of  expen- 
diture of  fluid  iffuing  out  of  an  orifice  fitted  with  additional  tubes. 

Propofiticn  2.  If  that  part  of  an  additional  cylindric  tube  which  is  nearefl:  the  fide  of  the 
refervoir  be  contracted  according  to  the  form  of  the  contradted  vein  of  fluid  which  ifTues 
through  a  hole  of  the  fame  diameter  in  a  thin  plate.  The  expenditure  will  be  the  fame  as  if  the 
tube  were  not  contrafted  at  all.  It  is  well  known,  that  when  the  water  of  a  refervoir  is 
AifFered  to  flow  through  a  circular  orifice  in  a  thin  plate,  the  fluid  vein  which  forms  the  jet 
becomes  contraded  at  a  fhort  diftance  from  the  orifice  ;  and  the  diameter  of  the  contrafted 
vein  is  nearly  0,8  of  the  diameter  of  the  orifice.  Poleni  firft  obferved,  that  by  applying  an 
additional  cylindric  pipe  to  the  orifice,  of  the  fame  diameter  as  the  orifice  itfelf,  and  from 
two  to  four  times  that  length,  the  expenditure  is  increafed  from  lOO  to  133.  To  account  for 
this  augmentation,  he  fuppofes  that  the  fluid  vein  is  lefs  contra6ted  in  pipes  than  after  pafling 
through  the  thin  plate.  The  fuppofition  was  not  unreafonable  ;  but  it  could  not  apply  to  the 
cafe  announced  in  this  propofition.  I  fliall  proceed  to  give  the  particulars  in  the  following 
experiment. 

Experiment  3.  To  the  aperture  P,  of  fig.  i,  I  applied  a  circular  orifice  1 8  lines  in  diameter, 
pierced  through  a  thin  plate.  Four  cubical  feet  of  water  flowed  into  the  veflel  Y  in  41 
feconds. 

I  then  applied  to  the  orifice  a  cylindric  tube  of  the  fame  diameter,  and  fifty-four  lines 
long.     The  four  cubic  feet  flowed  out  in  31  feconds. 

Inftead  of  this  fimple  cylindric  tube,  I  applied  the  compound  tube  of  fig.  5  ;  the  parts 
of  which  have  the  following  dimenfions  in  lines  :  AC=GI  =  MN  =  i8;  DF  =  14,5; 
AB=ii;BG=io;  GM=37;  AM  =58.  With  this  compound  tube  the  expendi- 
ture of  four  cubic  feet  of  water  was  made  in  31  feconds,  as  with  the  fimple  cylindric  tube. 

The  form  of  the  conical  portion  A  C  D  F  was  nearly  the  fame  as  that  of  the  contradion 
of  the  vein  which  ifllies  through  a  thin  plate.  The  vein  muft  therefore  have  pafiTed  through  a 
contradlion  nearly  equal  to  that  of  the  contracted  vein  from  a  thin  plate  j  the  expenditure 

'  never- 


Experlmtnts  on  the  lattral  CommunUathn  of  Motion  in  Fluids.  175 

neverthelefs  was  more  abundant,  in  the  fame  proportion  as  through  the  fimple  cjlindric 
tube.  It  follows,  therefore,  that  the  velocity  of  the  fe£lion  D  F,  and  of  the  whole  conoid 
A  C  D  F,  muft  have  been  greater  than  that  of  the  contradted  vein  from  a  thin  plate  ;  and  it 
remains  to  be  (hewn  what  was  the  caufe  of  this  augmentation  of  velocity  which  takes  place 
within  the  tube,  and  does  not  manlfeft  itfelf  externally. 

That  the  conical  tube  ACD  F  does  not  itfelf  caufe  any  augmentation  of  expenditure,  is 
evinced  by  the  following   . 

Experiment  4.  The  conical  tube  A  C  D  F,  from  which  the  remaining  part  D  G  MN  I  F 
was  feparatcd,  was. applied  to  the  orifice  P.  The  four  cubic  feet  were  emitted  in  42  feconds, 
which  is  the  time  of  the  expencc  through  the  orifice  itfelf  A  C  in  the  thin  plate,  with  the 
difference  of  one  fecond  only.  This  flight  variation  arifes  from  its"being  almoft  Impoffible  to 
make  the  tube  A  D  C  F  perfe£lly  of  the  form  of  the  natural  contra6led  vein. 

Propojition  3.  The  preffure  of  the  atmofphere  increafes  the  expence  of  water  through  a 
fimple  cylindric  tube,  when  compared  with  that  which  iflues  through  a  hole  in  a  thin  plate, 
whatever  may  be  the  direftion  of  the  tube. 

It  has  long  been  known,  that  a  heavy  fluid  which  moves  in  a  defcending  C)lindric  pipe 
tends  to  accelerate  its  motion.  The  inferior  parts  tend  to  feparate  themfelves  from  the 
fuperior,  and  by  that  means  caufe  the  prefTure  of  the  atmofphere  to  increafe  the  velocity  of 
the  fuperior  parts.  This  fucceffive  acceleration  of  gravity  cannot  take  place  in  an  horizon- 
tal or  afcending  pipe.  We  fhall  neverthelefs  find  that  the  prefTure  of  the  atmofphere  adts 
even  in  thefe  laft  Ctuations  to  increafe  the  velocity  of  fluid  within  the  pipe.  Certain 
queftions  of  legal  right,  which  arofe  in  my  country,  refpeifling  the  quantity  of  water  fun- 
plied  by  a  pipe  for  watering  lands  (canal  d'arrofement)  dire£led  my  attention  to  this  objeiSf, 
In  the  year  1791  I  made  the  following  experiments  publicly  in  the  Theatre  of  Natural  Phi- 
lofophy  at  Modena  : 

Experiment  5.  To  the  aperture  P,  fig.  i,  I  applied  a  cylindrical  pipe  54  lines  in  length 
and  18  in  diameter.  At  the  diflance  of  nine  lines  from  the  interior  orifice  P,  twelve  fmall 
holes  were  made, in  its  circumference.  When  thefe  fmall  holes  were  open,  the  four  cubic 
feet  ifTued  out  in  41  feconds,  in  the  fame  manner  as  through  a  thin  plate.  Not  a  fingle  drop 
pafTed  through  any  of  the  holes,  and  the  ftream  did  not  fill  the  tube.  The  holes  were  thea 
clofed  one  after  the  other  with  wet  fkin.  As  long  as  there  was  one  hole  open  the  expence  con- 
tinued the  fame ;  but  when  at  laft  all  the  twelve  holes  were  well  clofed,  the  fluid  ftream 
ifTued  out  in  a  body  which  filled  the  pipe,  and  the  four  cubic  feet  were  emitted  in  31  fecond?. 
Experiment  6.  To  the  cylindric  tube  K  L  B,  fig.  6,  18  lines  in  diameter  and  57  lines  lon:^, 
was  joined  the  glafs  tube  QJl  S  T,  at  the  diftance  of  eight  lines  from  the  interior  orifice  K. 
The  glafs  tube  v.as  plunged  in  coloured  watef  contained  in  the  vefTel  T.  When  this  ap- 
paratus was  applied  to  the  aperture  P,  fig.  I,  the  four  cubic  feet  of  water  flowed  out  in  31 
feconds.  The  coloured  liquid  T  rofe  in  the  tube  T  R  as  high  as  S>  at  the  height  of  24 
inches  above  the  furface  T. 

The  branch  RT  of  the  glafs  tube  was  (liortened  fo  that  RT  was  only  fix  inches  lon^Gr 
than  RQ.  The  efHux  being  then  permitted  to  take  place,  the  coloured  liquor  of  the  vefTel 
T  rofe  through  the  tube  RT,  and  mixed  with  the  water  which  flowed  from  the  refervoir 
through  KV,  both  of  which  flowed  out  at  V,  and  in  a  Ihort  time  the  vefTe!  T  w-tb 
emptied. 

I  repealed 


ij6  Experiments  en  the  lateral  Communication  of  Motion  In  Flulas, 

I  repeated  this  experiment  with  the  compound  tube  fig.  5,  and  the  refults  were  the 
fame. 

Experiment  7.  The  cylindrical  pipe  K  L  V,  fig.  6,  was  applied  in  an  afcending  and  nearly 
vertical  fituation  to  the  orifice  R,  fig.  8,  of  the  veflel  H  I,  of  which  the  end  H  Communicated 
by  an  opening  of  confiderable  extent  with  the  water  of  the  refervoirX,  fig.  i.  The  charge  on. 
the  upper  extremity  V  of  the  tube  was  27,5  inches.  I  inclined  the  tube  a  little  from  the 
vertical  direction,  in  order  that  the  jet  might  not  fall  back  upon  itfelf.  The  glafs  tube  Q_RT, 
fig.  6,  in  this  new  fituation  was  fo  difpofed  that  its  lower  extremity  was  immerfed  as  before 
in  the  coloured  liquid  of  the  veflel  T.  When  the  efflux  was  permitted,  the  expenditure  of 
four  cubic  feet  was  made  in  34  feconds  ;  and  the  coloured  liquid  rofe  in  the  tube  R  T  to  the 
height  of  near  20  inches.  With  the  dmt  charge  of  27,5  "inches  the  orifice  of  18  lines 
in  a  thin  plate  would  have  afforded  the  four  cubic  feet  in  4.5  feconds. 

Experiment  8.  A  cylindrical  vefiel  of  4,5  inches  diameter  had  in  its  vertical  fides  near 
the  bafe  a  circular  opening  of  4,5  lines  in  diameter,  opened  in  a  tliin  phte  of  tinned  iron. 
The  furface  of  the  water  contained  in  this  vefTel  was  8,j  inches  above  the  centre  of  the 
aperture.  The  water  was  then  fufFcred  to  flow  out  of  this  aperture  in  the  thin  plate,  and  its 
furface  was  deprefled  feven  inches  in  the  velTel  in  27,5  feconds  of  time. 

To  the  fame  aperture  was  applied  a  cylindric  tube  of  the  fame  diameter,  and  in  length 
1 1  lines.  The  veflel  was  filled  to  the  fame  height,as  before,  and,  the  water  bemg  fuff«red  to 
flow  out,  its  furface  was  depreffed  feven  inches  in  21  ftconds. 

The  fame  experiment  was  iifterwards  repeated  in  the  receiver  of  the  air-pump,  under 
which  the  mercurial  gauge  flood  at  no  more  than  JO  lines  in  height.  The  furface  of  the 
water  in  the  vefl"el  was  depreflTed  feven  inches  in  27,5  feconds,  whether  the  aperture  was 
made  in  a  thin  plate,  or  whether  it  was  provided  with  an  additional  cylindric  tube. 

The  height  of  the  coloured  water  in  the  tube  of  glafs  meafures  the  adtive  quantity  oTthe 
preflure  of  the  atmofphere,  which  is  exprted  on  the  furface  of  the  water  to  increafe  the  ex- 
penditure. For  example,  in  the  fixth  experiment  32,5  +  24  inches  charge  on  the  orifice 
P,  and  we  have  nearly  \/j2,5  :  ^56, 5  :  :  31":  41'',  as  is  required  by  the  Common  theory 
of  the  motion  of  fluids  which  ifTue  out  of  veflcls  by  a  fmall  aperture.  The  fame  obtains  in 
Experiment  7. 

Daniel  Bernoulli  made  the  7th  experiment  in  defcending  tubes,  and  in  diverging  conical 
tubes,  and  evplained  the  refult  merely  by  the  theory  of  confervation  of  living  forces.  Kuler 
and  d'Alembert  obferved  to  him,  that  the  preflure  of  the  atmofphere  was  concerned  in  the 
efFe£l*.  Though  the  cafe  of  the  defcending  rube  be  different  from  that  of  the  horizontal  or 
afcending  tube,  the  knowledge  of  the  firfl  of  thefe  two  cafes  may  neverthelefs  facilitate  the 
knowledge  of  the  fecond.  Befides  which,  the  caufes  which  a<ft  in  both  cafes  are  often  com- 
bined together,  and  it  is  neceflary  to  be  well  acquainted  with  both,  in  order  to  diftinguifli  the 
refult?.  On  this  account  it  is,  that  in  the  following  propofition  I  have  turned  from  my  prin- 
cipal fubjedl  for  a  moment  to  confider  the  firfl  cafe,  after  which  1  fliall  return  to  the  (econd. 

Propofition  4.  In  defcending  cylindrical  tubes,  the  uppsjr  ends  of  which  poflefs  the  form  of 
the  contraifted  vein,  the  expence  is  fuch  as  correfponds  with  the  height  of  the  fluid  above  the 
inferior  extremity  of  the  tube. 

*  D'Alembert,   Traite  des  Fluides,  Art.  149. 

The 


Experiment t  en  the  lateral  Communication  of  Motion  in  Fluicli.    ,  f^'j 

The  ancients  remarked,  that  a  defcending  tube  applied  to  a  refervorr  increafer  the  expen- 
diture*. Mariotte  eftimated  that  the  water  iflTues  through  C  Q_,  fig.  7,  with  a  velocity  near- 
ly the  mean  proportional^  between  the  velocities  arifing  from  the  two  heights  A  B,  A  Cf . 
Guillielmini  fought  for  the  caufe  of  this  augmentation  in  the  weight  of  the  atmofphere,  and 
determined  the  velocity  at  C  to  be  the  fame  as  would  arife  from  the  whole  height  A  C%.  In 
his  reafoning  he  fuppofes  that  the  prelTure  at  C  is  the  fame  for  the  ftate  of  motion  as  for  that 
of  reft }  which  is  not  true.  In  the  experiments  he  made  upon  this  objedl,  he  paid  no  regard 
either  to  the  diminution  of  expenditure  produced  by  the  irregularity  of  the  inner  furface  of~ 
the  tubes,  nor  the  augmentation  occafioned  by  the  form  of  the  tubes  themfelves.  By  a 
fihgular  accidental  concurrence,  one  of  thefe  errors  compenfated  for  the  other,  I  know  of 
no  other  decifive  experiment  on  this  head  fince  Guillielmini.  I  (hall,  therefore,  proceed  to 
eftablifh  the  propofition  upon  the  principle  of  virtual  afcenfion  combined,  with  the  preflure  of 
the  atmofphere,  and  that  in  a  manner  which  fhall  be  clear  of  every  objeflion,  of  theory  as  well 
as  of  experiment. 

Let  B  L  K  O  reprefent  a  conical  tube  adapted  to  the  form  of  the  contrafled  vein  §  ;  the 
cylindrical  tube  L  C  Q_K  is  of  the  fame  diameter  as  the  contracted  part.  The  fluid  ftratum, 
L  K,  continuing  to  defcend  through  LC,  tends  to  accelerate  its  motion,  according  to  the 
laws  of  gravitation  ;  and  confequently  when  it  paffes  from  L  K  to  M  N,  it  tends  to  detach 
itlelf  from  the  ftratum  which  follows,  or  in  other  words  it  tends  to  produce  a  vacuum 
between  L  K  and  M  N  ;  and  the  fame  efFe£l  takes  place  through  the  whole  length  of  the 
tube  L  C.  The  preflure  of  the  atmofphere  becomes  a£live  as  far  as  is  necefiary  to  prevent 
the  vacuum ;  and  its  aiStion  is  alike  both  at  the  furface  of  the  fluid  at  A,  and  at  the  inferior 
extremity  of  the  tube  at  C.  At  A  it  increafes  the  expenditure,  and  at  C  it  deftroys  the  fum 
of  the  accelerations  which  would  be  produced  along  L  C,  fo  that  the  fluid  remains  con- 
tinuous in  the  tube. 

Let  T  reprefent  the  time  which  the  continuous  column  of  fluid  L  C  Q_K  employs  to  pafs 
tlirough  the  tube  L  C,  whatever  may  be  the  velocity  at  L,  and  the  fucceflive  acceleration 
from  L  to  C.  And  if  we  fuppofe  this  fame  column  to  return  upwards  from  D  to  E,  it 
will  pafs  through  the  fpace  D  E  =  L  C  in  the  fame  time  T ;  during  which  it  will  lofe  all  the 
acceleration  it  acquired  from  L  to  C.  The  preflure  of  the  column  E  D,  continued  for  the  time 
T,  is  therefore  the  quantity  required  to  deftroy  the  fucceffive  acceleration  from  L  to  C,  and 
to  prevent  the  fluid  from  ceafing  to  be  continuous  in  the  tube  L  C  :  confequently  that  part  of 
the  preflure  of  the  atmofphere  which  is  exerted  at  C  Q,to  deftroy  the  fum  of  the  accelerations 
through  L  C,  is  equal  to  the  prefllire  of  a  column  E  D  of  a  fluid,  homogeneous  to  that  of 
the  refervoir  A  B.  And  flnce  the  fame  preflTure  muft  alfo  be  exerted  on  the  furface  A  of  the 
refervoir,  if  we  take  F  A  =  LC,  the  fluid  at  LK  will  poflefs  the  velocity  which  is  proper 
to  the  height FL  =  A  Cj  without  confidering  the  retardation  which  the  external  inequali- 
ties of  the  tube  L  C  QJC  muft  produce. 

•  Calix  devexus  amplius  rapit.  Frontin.  de  aquseduft.  Art.  36,  See  alfo  the  Pneumatics  of  Hero,  in  tlie 
mathcm.  vet.  cd.  1693,  page  157. 

t  Mouvemcfti  des  eaux,  part.  3,  difc.  j.  ' 

+  Epift.  hydroftatic.  Oper.  torn.  \.  page  iii. 

§  When  I  fpeak  of  the  form  of  the  contradted  vein,  I  always  mean  to  exprefs  the  conoid  formed  by  the  fluid 
•iffuing  from  an  orifice  through  a  thin  plate. 

Vol.  n. — July  1798.  A  a  Experiment 


178  Experiments  en  the  lateral  Communkation  of  Motion  in  Fluids, 

Experiment  IX.  i.  The  orifice  P  (fig.  i)  through  a  thin  plate  is  circular,  and  18  lines  in 
diameter.  The  charge  of  fluid  above  the  centre  of  the  orifice  is  40  inches.  Four  cubic  feet 
of  water  were  emitted  in  38  feconds. 

2.  To  the  orifice  P,  fig.  i,  I  applied  the  tube  A  C  D,  fig.  4,  the  upper  end  of  which  A  C 
had  the  form  of  the  contratSted  vein.  The  diameter  at  A  was  18  lines  in  length,  AD  31 
inches,  and  the  fituation  of  the  tube  horizontal.  The  expenditure  of  four  cubical  feet  was 
made  in  48  feconds. 

3.  The  fame  orifice  and  the  fame  tube  were  applied  to  the  horizontal  bottom  of  the  re- 
■fervoir  fig.  7,  fo  that  the  tube  was  vertical,  and  A  C  =  40  inches,  or  the  height  of  the  charo-c 
in  the  two  former  experiments.  The  four  cubic  feet  flowed  out  in  48  feconds,  as  in  the 
fecond  experiment. 

Experiment  X.  The  laft  defcribed  experiment  was  repeated  with  a  circular  aperture  of 
li,2  lines  in  diameter.  The  extremity  A  C,  of  the  tube  fig.  4,  had  the  form  of  the  con- 
tra£ted  vein ;  the  end  A  having  the  fame  diameter  as  that  of  the  orifice.  The  other  cir- 
cumftances  were  as  in  the  preceding  cafes.  In  the  difpofition,  according  to  the  firft  cafe 
four  cubical  feet  of  water  flowed  out  in  98  feconds  j  in  the  fecond  cafe  the  time  was  130 
feconds  ;  and  in  the  third  cafe  129  feconds. 

In  each  of  thefe  two  experiments  the  tubes  and  the  expence  of  water  were  the  fame  for 
the  fecond  and  the  third  cafes  ;  whence  it  follows,  that  the  force  by  which  the  expenditure 
was  governed  was  the  fame  in  both  cafes.  Now  the  force  which  a£ts  in  the  fecond  cafe  is  the 
fame  as  in  the  firfl ;  and  confequently  the  fame  force  likewife  zCts  in  the  firfl  and  third  cafes. 
All  the  difference  of  the  refult  between  the  firft  cafe  and  the  two  following  arifes  from  the 
retardation  produced  by  the  inequalities  of  the  internal  furface  of  the  tubes. 

Experiment  XI.  The  height  A  B,  fig.  7,  being  conflantly  32,5  inches,  and  the  orifice  B  O 
1 8  lines  in  diameter,  the  tube  B  O  C  Q_was  applied  to  the  orifice  itfelf,  the  fuperior  extremity 
of  this  tube  having  the  form  of  the  contrafted  vein.  When  the  length  of  the  tube  was  varied, 
the  times  of  the  efflux  of  four  cubic  feet  of  water  were  as  in  the  following  table. 


Length  of  the  tube 
BC  in  inches. 

Time  of  efflux   of 
four  cubic  feet  by 
experiment. 

Time  according  to 
the  theory  with- 
out confuiering  the 
retardation. 

DifTcrence  between 
the  theory  and  ex- 
periment. 

Retardations  com- 
puted   from     the 
following  experi- 
ment. 

3 
12 

24 

4«" 
38" 

35" 

40" 

35",2 

3l",2 

1" 

2",8 

3",8 

i",3 
3",4 

s"- 

The  fifth  column  of  this  table  is  calculated  from  the  proportion  of  retardation  produced  by 
the  irregularities  of  the  internal  furface  of  the  tubes.  Citizen  BofTut  has  obferved,  that  thefe 
retardations*  increafe  rather  in  a  lefs  ratio  than  the  velocity  of  the  flream.  This  is  perhaps 
the  reafon  of  the  difference  obferved  between  the  fourth  and  fifth  columns. 

Experiment  XII.  I  applied  to  the  orifice  P,  fig.  i,  the  fame  tubes  as  in  the  foregoing  expe- 
riment one  after  another  in  an  horizontal  fituation,  the  height  of  the  charge  being  conftant- 


*  Hydrodyn.  Art.  bit. 


On  the  EfeB  of  a  MUture  of  Tin  with  Getd. 


ir^ 


!y  32,5  inches  above  the  centre  of  the  orifice.     The  times  of  emiffion  were  as  in  the  fol- 


lowing table. 


L.cngtii  or  tlic  tube 
B  C  in  inches. 

lime  of  •fflux  of 
four  cubic  feet. 

Differences. 

0 

3 
12 

24 

41" 

4S" 
48'' 

0 

4" 

7" 

I  tnuft  here  obferve,  that  the  vifcidity  or  mutual  adhefion  of  the  particles  of  the  water  *  i$ 
of  very  little  confequence  to  the  increafc  of  expenditui-e  through  the  orifice  B  O,  fig-  7,  by 
the  additional  tube  B  C.  For  as  foon  as  a  fmall  hole  is  opened  at  K  the  increafe  of  expendi- 
ture diminifties  or  entirely  ceafes,  and  the  fluid  is  no  longer  continuous  in  the  tube. 

We  will  now  return  to  tubes  in  the  horizontal  and  afcending  fituations. 

{_  To  bi  continued.  ] 


viir. 

Experiments  and  Obfervations  on  the  EffeEl  of  Annealing  a  Plate  of  Metal,  conftjling  of  fine  w 
alloyed  Gold,   with  one  twenty-fourth  Part  of  Tin.     By  MATTHEW  TiLLET. 

[  Concluded  from  page  i4z.  ] 


I 


HESITATED  to  ufe  my  gold  of  24  carats,  from  the  juft  fear  I  had  that  it  would 
lofe  the  advantage  of  being  the  duflile  of  metals,  and  that  I  could  not  reftore  this  property 
but  by  the  method  of  parting.  For  this  reafon  I  determined  to  begin  my  experiments  on  a 
more  decifive  fcale  than  the  former,  upon  gold  of  22  carats,  or  alloyed  with  -r-'^th  part  of 
copper.  In  this  manner  I  fhould  repeat  fome  of  the  experiments  related  by  Mr.  Alchorne, 
from  which  he  has  conftantly  inferred  that  tin,  mixed  in  a  certain  proportion  with  gold  of 
this  fame  finenefs  of  22  carats,  does  not  deprive  it  of  its  dudlility. 

I  therefore  alloyed  i  gros  24  grains  of  tin  taken  from  the  ingot  deprived  of  arfenic, 
which  I  have  mentioned,  with  4  ounces  of  gold,  the  finenefs  of  which,  namely  22  carats, 
was  perfeftly  well  afcertained.  Thefe  two  metals,  reduced  into  fmall  pieces,  were  mixed 
together,  put  into  a  crucible,  and  urged  by  the  ftrong  heat  of  a  forge  with  two  pair  of  bel- 
lows. When  their  fufion  appeared  to  be  complete,  I  poured  the  metal  into  a  fmall  ingot- 
mould  proportioned  to  the  quantity. 

The  ingot  thus  obtained  had  loft  fcarcely  any  thing  of  the  weight  of  the  two  metals  that 

compofed  it,  which  was  a  proof  that  the  tin  had  united  and  incorporated  with  the  four 

^    ounces  of  gold.     But  on  attempting  to  bend  the  ingot,  which  was  about  fix  inches  long 

and  not  more  than  two  or  three  lines  thick,  I  remarked,  contrary  to  the  nature  of  gold  of  21 

carats,  that  it  was  rigid,  and  would  have  required  a  confiderable  effort  to  give  it  any  degree 

•  Gravefande  and  others  have  attributed  the  increafe  of  expenditure  through  defcending  tubes,  to  the  natural 
cohffion  of  the  particles  of  water.    V. 

A  a  a  of 


x5o  On  the  Effi5l  of  a  Mixture  of  Tin  with  Gold. 

of  curvature,  or  bring  it  to  the  flexibility  it  would  have  pofleffed  if  no  tin  had  entered  into 
its  compofition.  Hence  I  clearly  faw,  that  this  rigidity  announced  a  diminution  of  its 
du£tility  ;  that  the  interpofition  of  a  fubftance,  which  was  foreign  to  the  gold,  and  inca* 
pable  by  its  nature  of  maintaining  the  cohefion,  was  the  caufe  of  this  want  of  flexibility  ; 
and  sthat  it  could  be  attributed  only  to  the  tin,  becaufe  copper  alone,  mixed  with  fine  gold, 
though  it  gives  a  greater  degree  of  hardnefs  and  rigidity  than  it  before  pofleffed,  deprives  it 
of  very  little  of  its  ductility. 

After  this  firfl  obfervation  on  the  ftate  of  the  ingot  afforded  by  the  experiment,  I  came 
to  the  more  decifive  proof  by  hammering,  particularly  vs^ith  the  edge  of  the  hammer,  in  or- 
der that  the  bar  might  be  lengtliened,  and  by  that  means  fubmitted  to  the  molt  decifive 
proof.  I  did  not  obferve  during  the  continuation  of  this  proccfs,  till  the  bar  was  reduced 
to  about  two-thirds  of  its  firft  thickncfs — I  did  not  obferve,  I  fay,  that  its  edges  were 
cracked,  or  exhibited  much  of  the  appearance  of  brittlenefs  ;  but  as  I  was  apprehenfive 
that  this  accident  might  happen  by  too  long  hammering,  I  divided  the  bar  by  cutting  off 
the  part  which  had  been  hammered  out.  This  part  was  placed  in  the  midfl  of  lighted 
charcoal,  in  order  that,  by  a  moderate  annealing,  it  might  recover  the  ftate  of  malleability 
it  poffeffed  before  it  was  hammered. 

But  when  I  went  to  take  it  out  of  the  fire,  where  it  had  undergone  no  greater  heat  than 
a  cherry-red,  I  found  it  divided  into  two  parts.  After  having  fuffered  thefe  to  cool,  I 
forged  them  again.  They  were  extended  with  confiderable  eafe,  though  with  fome  cracks 
at  the  edges ;  but  they  did  not  yet  fatisfy  the  whole  of  my  enquiries.  I  therefore  annealed 
one  of  the  two  laft-mentioned  pieces  a  fecond  time,  and  referved  the  other  in  its  hard 
hammered  ftate  to  be  paffed  between  the  laminating  rollers.  The  annealed  part,  which 
might  have  the  thicknefs  of  about  a  ftiilling  (piece  de  douze  fols),  broke  in  the  fire,  though 
the  heat  was  very  gentle,  into  four  or  five  portions.  The  longeft  of  thefe  portions,  which 
beft  refifted  the  action  of  the  fire,  bent  and  twifted  itfelf,  and  fhewed,  by  this  ftate  of 
ftrong  contradtion  in  different  diredtions,  that  it  had  tended  to  break  and  become  divided 
into  fmall  portions  fimilar  to  thofe  which  had  already  feparated  from  it. 

This  accident  gave  me  reafon  to  fufpeft  that  the  aflies,  upon  which  I  had  annealed  the 
plate  of  gold  which  broke -in  pieces,  might  alfo  contain  certain  portions.  I  was  not  de- 
ceived ;  for  the  aflies  being  carefully  waftied  left  three  or  four  fragments  which  the  ignited 
coals  had  prevented  from  being  feen. 

It  has  been  remarked,  that  I  referved  orte  of  the  two  parts  of  the  portion  of  the  ingot 
which  I  had  forged  a  fecond  time,  and  that  I  had  kept  it  in  its  hammer-hardened  ftate.  I 
could  not  doubt,  after  the  laft-recited  experiment,  that  any  attempt  to  anneal  this  portion, 
even  by  the  moft  moderate  heat,  would  be  attended  with  the  fame  confequence,  namely, 
that  it  would  break  in  pieces.  I  therefore  detcrniined  to  extend  it  ftill  more  between  the 
rollers,  fetting  them  up  very  gradually  in  order  that  the  fracture,  if  it  fliould  take  place, 
might  be  principally  owing  to  the  brittlenefs  of  the  material,  and  not  to  the  force  of  com— 
preflion  to  which  it  was  fubjefted.  By  this  management  1  fucceeded  in  extending  the 
nietal  to  double  its  length  notwithftanding  its  hardnefs.  In  this  manner  it  was  rendered 
as  thin  as  ftrong  paper  ;  though  it  muft  be  ccnfeffed  that  the  edges  were  cracked  through 
their  whole  length  like  the  teeth  of  a  faw.  But  this  accident  is  not  at  all  furprifing,  when 
it  is  confidercd  that  gold,  though  alloyed  Cmply  with  coppet,  whatever  may  be  the  caufe, 

does 


On  the  EffeEl  of  a  Mixture  of  Tin  with  Gold,  1 8l 

does  not  poflefs  its  ufual  duclility,  particularly  when  it  Is  laminated  very  thin  without  re- 
peated annealing  as  the  metal  becomes  hard. 

It  might  be  prefumed,  in  refleding  on  the  experiment  I  have  related,  that  the  frafture 
of  the  pieces  of  gold  was  owing  to  an  incomplete  fufion  or  unequal  mixture  of  the  two  me- 
tals. I  was  aware,  from  this  notion,  that  it  was  proper  to  melt  the  ingot  over  again  with 
all  the  parts  which  had  been  feparated  from  it,  and  to  negleft  no  precaution,  after  well 
mixing  it,  that  it  fhould  be  poured  out  in  perfedl  fufion.  At  the  moment  this  ftate  of  fu- 
fion was  obtained,  I  threw  a  fmall  quantity  of  calcined  borax  upon  the  metal.  In  order  that 
its  furface  might  become  clear,  and  every  foreign  fubftance  might  be  carried  to  the  circum- 
ference. No  other  confequence  could  arife  from  this  ufe  of  borax  than  a  greater  foftnefs 
in  the  compound,  and  confequently  lefs  rifk  of  its  breaking  when  it  came  to  be  fubjefted  to 
the  hammer. 

All  my  precautions  were  ufelefs.  I  forged  one  end,  which  was  lengthened  very  well 
without  any  perceptible  crack ;  but  the  extremity  of  this  ingot,  afterwards  reduced  to  a 
fmall  thicknefs  and  expofed  to  the  annealing  heat,  became  divided  into  feveral  parts,  the 
longed  of  which  was  contorted,  and  would  no  doubt  have  broken  If  the  heat  had  been 
ftronger,  or  continued  for  a  greater  length  of  time. 

Though  the  experiment,  of  which  I  have  related  the  refult,  on  the  mixture  of  one  part  of 
tin  and  24  parts  of  gold  of  22  carats,  might,  In  ftriclnefs,  have  been  fufficient  to  prove  that 
this  alloy  deprives  gold  of  great  part  of  its  dudlility,  and  expofes  it,  while  annealing,  to  an 
accident  which  artifts  would  fcarcely  be  able  to  avoid,  from  the  neceflity  they  are  under  of 
'  continually  reftoring  the  malleability  of  the  gold  they  work,  by  annealing  It  after  it  has  be- 
come hard  under  the  hammer  ;  I  neverthelefs  thought  it  proper  to  lay  afide  the  objedlion  I 
had  to  deprive  my  fine  gold  of  its  dudlillty,  which  could  not  be  reflored  but  by  a  new  part- 
ing eflay,  and  to  repeat  the  experiment  by  ufing  gold  of  24  carats  In  fuch  a  quantity  that 
my  operation  might  be  compared  with  that  of  Mr.  Alchorne,  from  which  chiefly  he  has 
drawn  his  conclufion. 

I  therefore  employed  6  ounces  of  fine  gold  and  2  gros  of  tin  for  this  new  experiment. 
The  firft  of  thefe  metals  was  divided  into  a  great  number  of  pieces,  and  I  had  Included  the 
two  gros  of  tin  in  two  leaves  of  gold  taken  from  the  6  ounces,  rolled  out  very  thin,  and  fo 
flexible,  after  arinealing,  that  they  perfectly  enveloped  the  tin.  After  having  put  one  part 
•f  the  gold  at  the  bottom  of  a  fmall  crucible,  I  placed  the  tin  wrapped  up  in  gold  upon  it, 
and  over  this  I  put  the  remainder  of  the  gold. 

When  the  whole  of  the  two  metals  was  In  perfeft  fufion,  I  poured  them  fpcedily  into 
an  ingot  mould,  which  I  had  before  ufed,  and  obtained  an  ingot  rather  longer  and  cleaner 
than  the  two  former. 

As  foon  as  It  was  cold,  I  forged  one  of  Its  extremities  with  the  edge  of  the  hammer^ 
It  was  lengthened  without  any  perceptible  crack;  and  when  it  was  reduced  to  the  thicknefs 
of  one  line,  or  thereabouts,!  cut  it  off  for  feparate  treatment.  By  moderate  annealing  It  main- 
tained its  integrity;  and,  with  the  exception  of  a  few  cracks,  it  paffed  the  laminating 
rollers  without  breaking.  As  I  was  fearful,  neverthelefs,  that  it  might  break  in  fome  part  if 
I  continued  to  laminate  it,  I  gave  it  a  flight  annealing.  It  had  fcarcely  acquired  a  cherry 
rcdnefs  between  the  charcoal  before  it  broke  into  five  or  fix  parts,  fome  of  which  were 
fimply  bended  or  twilled,  and  others  flat  as  they  quitted  the  rollers.    Among  the  annealed 

6  pieces 


t82  On  the  Effe^  of  a  Mixture  of  Tin  with  GoM. 

pieces  of  this  extremity  of  the  ingot,  there  was  one  fufficiently  long,  though  a  little  curled, 
which  I  laminated  a  fecond  time,  with  the  determination  of  rendering  it  very  thin  without 
the  leaft  annealing.  It  acquired  at  ieaft  double  the  length  it  had  at  firfl:  without  breaking ; 
and,  if  we  except  the  two  fides  of  this  plate  which  were  cracked,  the  body,  or  main  piece, 
was  entire.  It  was  fpongy,  and  might  be  confidered  as  if  formed  out  of  an  ingot  of  com- 
mon gold  containing  no  tin,  but  not  poiTeffing  the  whole  of  its  natural  du£tility. 

It  follows,  from  thefe  experiments,  that  gold,  whether  fine  or  alloyed,  when  perfe£lljr 
fufed  with  a  fmall  portion  of  the  fined  tin,  acquires  rigidity  and  hardnefs  by  the  mixture; 
that  it  lofes  fomewhat  of  its  diftinguilhing  colour;  and  that  it  may,  indeed,  by  careful  ma- 
nagement, be  extended  to  a  certain  degree  by  the  hammer,  or  flill better  by  the  rollers;  but 
that,  as  it  cannot  be  annealed  without  danger  of  breaking,  it  is  by  this  defect  deprived  of 
the  eflential  advantage  of  recovering  its  original  foftnefs  after  it  has  been  flrongly  hammer 
hardened.  It  is  not  but  by  careful  management  in  the  ufe  of  the  hammer,  and  by  frequent 
annealing,  that  artifts  employed  on  works  of  gold  and  filver  fucceed  in  obtaining  them 
without  cracks,  and  bringing  them  to  a  ftate  of  perfeilion,  without  being  obliged  to  have 
recourfe  to  folder  to  repair  the  defe6ls  which  exceflive  hardnefs  under  the  hammer  would 
occafion.  How  much,  therefore,  ought  gold-workers,  who  continually  have  this  metal  in 
tlieir  hands,  to  be  attentive  to  prevent  the  introdudlion  of  tin  in  their  workftiops,  and  never 
to  employ  fuch  compounds  of  gold  as  are  fubje£l  to  break,  or  even  to  warp,  while  annealing? 
The  expence  of  refining,  which  they  would  pay  for  depurating  fuch  compounds,  would  be 
of  lefs  confequence  to  them  than  the  lofs  of  time  required  for  the  careful  management  of 
fuch  gold  contaminated  by  tin,  even  if  they  did  fucceed  in  ufing  it,  and  were  not  often  forced 
to  abandon,  after  much  labour,  a  work  nearly  finiflied. 

I  do  not  doubt  but  that  Mr.  Alchorne,  if  he  had  carried  his  experiments  further,  or  had 
confidered  them  with  regard  to  the  methods  of  gold-workers,  who  frequently  expofe  to  the 
fire  fuch  pieces  as  they  propofe  to  raife  or  fafhion  according  to  their  defigns ;— 'I  do  not 
doubt,  I  fay,  but  that  Mr.  Alchorne  would  have  cautioned  artifts  againft  the  accidents  to 
which  gold  alloyed  with  tin  is  fubjeft  while  annealing.  He  has  obferved  a  degree  of  duc- 
tility in  this  matter,  and  has  not  prefumed  that  it  might  be  taken  away  by  means  of  fire, 
which,  on  the  contrary,  reftores  to  moft  metals  their  flexibility  and  facility  of  working. 

The  opinion  which  has  hitherto  been  maintained  refpedling  the  danger  of  a  very  fmall 
alloy  of  tin  with  gold  is  therefore  well  founded.  In  faft,  it  muft  have  been  difficult  for  fuch 
an  opinion  to  have  prevailed  without  foundation,  when  a  multitude  of  artifts  are  in  a  fitua- 
tion  to  verify  the  fad,  and  muft  be  Immediately  ftruck  with  the  brittlenefs  of  fuch  gold, 
and  be  moft  ftrongly  interefted  to  difcover  its  caufe. 

This  example  of  an  opinion  generally  received  and  fupportcd  on  conftant  fails,  which 
the  greater  number  of  artifts  have  rather  adopted  than  examined  ;  this  example  proves  that 
we  ought  not,  without  the  greateft  caution,  to  attack  fuch  received  notions,  particularly 
when  as  in  the  prefent  cafe  it  is  in  no  refpe£l  hurtful,  and  only  tends  to  render  the  work- 
men more  cautious  in  the  ufe  of  the  moft  valuable  of  metals.  ♦ 

The  experiments  of  Mr.  Alchorne  have  long  remained  upon  record  in  the  Philofophical 
Tranfa£lions,  and  have  by  that  means  acquired  a  fandion  which  demands  a  greater  degree 
of  attention.  I  have  had  no  other  aim  in  repeating  them,  and  exhibiting  an  efiential  depen- 
dant fad  not  mentioned  by  that  flsilful  aflayer,  than  to  give  ufeful  information  to  artifts, 

and 


Oil  the  EffcB  of  a  Mixture  of  Tin  with  Cold.  183 

and  contribute  to  the  certainty  of  their  operations.  I  think  this  purpofe  will  be  anfwercd, 
by  leaving  them  in  pofTeflion  of  all  the  apprehenfion  they  have  hitherto  entertained  refpeft- 
ing  the  mixture  of  tin  with  gold. 

If  it  Ihould  be  thought  that  my  experiments  may  not  be  as  conclufive  as  at  firft  (ight 
they  appear,  they  will  at  lead  produce  no  other  effed  than  that  of  giving  artifts  fome  ufe- 
lefs  trouble.  They  will  with  reafon  attend  to  them,  however  fuperfluous  they  may  be 
fuppofed,  and  will  prefer  the  care  I  recommend  to  the  anxiety  of  working  upon  materials 
rendered  fufpicious  by  their  harfhnefs,  and  fuppofed  to  be  incapable  of  annealing  on  ac- 
count of  their  containing  tin. 

If  it  be  allowable  to  form  fome  conje£tures  on  the  frafture  of  plates  of  gold  containing 
tin,  when  fubjefted  to  the  annealing  heat,  it  may  be  prefumed,  that  the  tin,  which  very 
fpeedily  melts,  while  the  gold  requires  a  very  ftrong  heat  for  its  fufion — it  may  be  pre- 
fumed, I  fay,  that  the  parts  of  the  tin  intermixed  in  a  fort  of  proportional  equality  with 
thofe  of  the  gold,  tend  to  feparate  by  a  fpeedy  fufion  and  at  a  very  gentle  degree  of  heat; 
that  they  remain  without  confidence  between  the  parts  of  the  gold,  while  the  latter  pre- 
ferve  the  whole  of  their  folidity,  and  do  not  lofe  it  even  by  the  annealing  heat ;  whence  it 
feems,  that  the  parts  of  the  precious  metal,  when  ignited  among  the  coals,  having  no  longer 
the  folid  connedlion  formed  by  the  tin,  but,  on  the  contrary,  having  an  infinite  number  of 
foiall  cavities  occupied  by  particles  of  that  metal  in  fufion,  muft  tend  to  difunion;  whereas 
the  fame  accident  does  not  take  place  in  the  pieces  which  have  refilled  the  annealing,  and 
have  been  laminated  after  cooling,  becaufe  the  particles  of  tin  have  become  folid  by  cooling, 
and  have  recovered  their  original  flate  of  union  with  the  gold. 

This  fra£ture  of  the  compound  does  not  take  place  with  an  alloy  of  gold  and  copper,  for 
an  oppofite  reafon  to  that  which  has  here  been  explained  ;  namely,  becaufe  thefe  two  me- 
fals  require  nearly  the  fame  heat  for  their  fufion.  The  efFe6t  of  annealing  being  therefore 
equal  upon  both,  the  metals,  notwithftanding  this  treatment,  preferve  their  natural  con^ 
fiftence,  even  though  the  heat  be  carried  near  the  point  of  fufion. 

In  fupport  of  the  opinion  I  have  prefented,  refpeding  the  fracture  of  thefe  plates  of  gold, 
I  mull  obferve  that,  by  examining  theit  furfaces  under  the  microfcope,  a  great  number  of 
particles  of  tin  may  be  diftinguiflied,  which  appear  to  be  difengaged  from  the  pores  of  the 
gold;  that  thefe  furfaces,  being  applied  by  an  annealing  heat  to  a  plate  of  iron  or  filver, 
adhere  ftrongly  by  virtue  of  thefe  particles  of  tin  •,  that  they  cannot  be  feparated  but  with 
difficulty,  and  even  tear  up  fome  flight  portions  of  the  metal  on  which  tliey  were  annealed 
when  they  are  fo  feparated. 

I  fball  conclude  thefe  details,  into  which  the  fubje£l  of  my  experiments  has  forced  me  to 
enter,  by  remarking  that  the  plates  of  gold  here  fpoken  of  may  be  kept  entire,  when  annealed, 
on  a  flat  plate  of  metal,  on  which  they  may  remain  fupported  till  cold ;  whereas,  if  placed 
on  ignited  charcoal,  they  frequently  bend  or  twill,  and  are  fubjeft  to  break,  particularly  if 
aot  attempt  is  made  to  take  them  out  with  the  tongs  in  their  ignited  ftatc. 


IX.  On 


1^4  ^  ^iotatlon  rej^ditttg  the  Figure  ef  the  Earth,  ^e, 

IX. 

On  the  Ktioivledge  of  the  Ancients  refpeBing  Gravity.     By  a  Ctrrefpondent. 

JL  H  E  refpedable  publifliers  of  the  "  Journal  of  Natural  Philofophy,  Chemiftry  and  th« 
Arts,"  are  defired  to  fubmit  to  the  infpedlion  of  its  ingenious  Author  the  following  obfer- 
vations  relative  to  a  Note  at  page  85  of  the  15th  Number.  ( Vol.  II.) 

"  In  the  treatife  of  *  Plutarch  De  Placitls  Philofophorum,'  occurs  no  paflage  referring  to 
the  'vibration  of  a  body  through  the  centre  of  the  earth  to  the  antipodes,  and  to  the  reten- 
tion of  the  moon  in  its  orbit  by  the  combination  of  the  proje£iiIe  and  gravitating  forces.' " 

The  paffage  alluded  to  is  probably  in  the  treatife  "  De  Facie  qua;  in  Orbe  Luna:  ap- 
paret ;"  but  there,  fo  far  from  proving  a  gravitating  force,  the  abfurdity  of  the  fuppofition  is 
endeavoured  to  be  {hewn. 

Ed.  Oxon. — 8vo.  T.  iv.  §  ^.  ^iroo-of  i;v  Jf  ««  auxriov,  av  ra  isa^a^o^a,  wafaSbloi;  aixuvtaiai  ffn- 

STOi  TW  cm  TO  /JLCffOV  fo^av  eivaysa-tv.     'H,  ri  -aa^a^a^ov  kk  ivsrtv  ;   Ouxt  Ttir  yw  (7(paioay  tivai,  thAi- 
fiavTct  ^aBv)  Hat  yj'i  *'"  ava%a>.t!c;  sxs-rav ;   OuK  avTiwoJitf  omeiv,  auTtz^  ^^iTraf,  jj  yaXeccTa;,  rpaTTivrct 
ava  ra  xara  t»i   tji  'EpohxoiJ''i"^i  j    "i^as  ^e  aulni  /in  wf  0;   o^6a(  ^iStixola;,   aA^a  wPiayiOi/;  cpri/xemv 
aTTOvBvovTai,    UTinq  01  fxs6vovTis ;    Ou  /xi/Sjrsj  x'^"'''«^«'''?«5  ^'«  ^aflsf  tds  />){  ^e^ofisvs;,  olav  tiixavlcH 
ispoi  TO  jMEiroy,  iratirflai  /xri^evoi  aTtavru^o;,  //.noc  vTrepiioovroi  j  Ei  Si  f  u^ttw  kutoj  (pt^ojAivai  to  /x^jov  uttcp- 
Cax^ouv,  ai/foj  o%icra  rfEf £o-9«i  kcu  avaxa//,'xlciv  wtt'  avlm.     Thus  tranflated  by  Philemon  Hol- 
land— "  But  we  ought  not  to  give  ear  unto  philofophers,  if  they  would   maintain  flrange 
"  paradoxes  by  other  pofitions  as  abfurd,  or,  to  confute  admirable  opinions,  devife  others 
"  much  more  extravagant  and  wonderful,   like  as  thefe  here  who  broach  and  bring  in  a 
"  notion,  forfooth,  tending  unto  a  middle,    wherein,  what  abfurdity  is  there   not  ?  Hold 
•«  not  they  that  the  earth  is  as  round  as  a  ball,  and  yet  we  fee  how  many  deep  profundities, 
"  haughty  fublimities  and  manifold  inequalities  it  hath  ?  Affirm  not  they  that  there  be  an- 
**  tipodes  dwelling  oppofite  one  unto  another,  and  thofe  flicking  as  it  were  to  the  fides  of  the 
•'  earth  with  their  heels  upward  and  their  head  downwards  topfy  turvy,  like  unto  thefe  wood- 
*'  worms  or  cats  (r. newts)  which  hang  by  their  (harp  claws?  Would  not  they  have  even  us  alfo 
*'  that  are  here,  for  to  go  upon  th?  ground  not  plumb  upright,  but  bending  or  inclining  fide- 
"  long,  reeling  and  flaggering  like  drunken  folk  ?  Do  they  not  tell  us  tales,  and  would  make 
*'  us  believe,  that  if  bars  and  mafles  of  iron  weighing  a  thoufand  talents  a  piece  were  let  fail 
"  down  into  the  bottom  of  the  earth,  when  they  came  once  to  the  middle  centre  thereof, 
*'  will  ftay  and  reft  there,  albeit  nothing  elfe  came  againft  them  nor  fuftained  them  up  ?  And 
**  if  peradventure  by  fome  forcible  violence  they  fliould  pafs  beyond   the  faid  midft,  they 
•'  would  foon  rebound  back  thither  again  of  their  own  accord?" 

So  true  is  the  obfervation  of  Cleomedes,  that  thofe  among  the  ancients  who  treated  of 
natural  philofophy  were  much  confufed,  and  on  this  head  greatly  erred,  not  beino-  able  to 
difcern,  that  fince  the  world  was  of  a  fpherical  figure,  the  centre  muft  of  ncceffity  be  inferior 

to  every  part  of  it — ai  h  XoiTrai  crx^o-c  'TrofAw  ■7rape(rxov  Tapaxw  Toif  va)\aioTcpoi;  rav  ^ua-ixav ou 

SuvJi^EvToiv  ETTirtia'ai,  oti  ev  tm  xoirfM,  ^(pMpixa  ra  (^xnixstri  ovli,  x»ra  /xcv  uTto  wwlof  aum,  to  fica-analov 
tivcci  amyxouov.    De  Meteoris,  ed.  Balforei,  1605,  p.  9. 

Rtmarki 


On  Gravlix,  ^(.\ — Defcripthn  sf  Gibraltar.  igj 

Remarks  on  the  preceding  Connnuriicat'ton. 
UPON  confuking  the  original,  to  which  I  referred  by  memory,  in  the  note  at  page  85  of 
the  prefeiit  volume,  I  perceive  that  both  the  paflages  alluded  to  are  in  the  tregtifc-  De  Facie 
in  OrbeLunaj.  I  was  mifled  by  another  obfcure  paflage  in  the  third  book  De  PLicitfs 
Philofophorum,  under  the  title  Tlipi  kivmiu;  yn;.  ly.  where  it  is  faid  that  Philolaus  the  Pytha- 
gorean held  that  the  earth  revolves  in  an  orbit  (■aepi  ro  •srt/f)  around  the  fire,  and  that 
Heraclides  of  Pontus  and  Ecphantus  the  Pythagorean  attributed  motion  to  the  earth,  not 
progrefl'ive,  but  rotatory,  from  weft  to  eaft.  I  did  not,  as  my  learned  correfpondent  feenis 
to  intimate,  pretend  to  fay  that  either  Plutarch  or  the  fpeakers  in  his  treatife  exhibited  the 
doflrines  of  the  gravitating  and  projeftile  forces,  as  being  worthy  of  adoption.  My  implied 
argument  was,  that  fince  they  are  extant  in  a  paffage  of  fome  length,  there  were  in  faiEt  phiio- 
fophers  among  the  ancients  who  had  maintained  and  developed  them  ;  though,  from  a  variety 
of  well  known  caufes,  this  doflrine  remained  without  diftindlion  among  other  ill-digefted  or 
falfe  fyftems.  The  combination  of  thefe  forces  in  the  moon,  which  occurs  in  the  paragraph 
to  which  Theo  replies,  in  my  correfpondent's  quotation,  isuairotTn  ftsv  crtXwyi  Pon9sia  "apoirofitf 
mtctiv,  *i  xivriffi;  avTti  kou  ro  pi^oihi  Ttii  vcpiayenyn;'  D.a-'n'ip,  &c.  "But  the  moon  is  prevented  from 
"  falling  by  its  motion,  and  the  violence  of  its  revolution ;  as  bodies  placed  in  a  flin^  and 
"  whirled  round  do  not  drop  out.  For  every  body  will  be  carried  according  to  its  natural 
•'  motion,  if  not  diverted  by  fome  other  caufe.  The  moon  is  not,  therefore,  carried  in  the 
*'  dire£lion  of  (or  by  j  its  weight,  becaufe  its  circular  motion  oppofes  this  tendency," 


AJhart  Minerahgtcal  Defcrlpt'ion  of  the  Mountain  of  GibraUar.     By  Major  Imrie*.  ' 

X  H  E  mountain  of  Gibraltar  is  fituated  in  36°  9' north  latitude,  and  in  5°  ly'eafllonc^itude 
from  Greenwich.  It  is  the  promontory  which,  with  that  of  Ceuta  upon  the  oppofite  coafl 
ofBarbary,  forms  the  entrance  of  the  ftraits  of  Gibraltar  from  the  Mediterranean;  and 
Europa  Point,  which  is  the  part  of  the  mountain  that  advances  moft  towards  Africa,  is 
generally  regarded  as  the  moft  fouthern  promontory  in  Europe.  The  form  of  this  moun- 
tain is  oblong  ;  its  fummit  a  (harp  craggy  ridge  ;  its  direction  is  nearly  from  north  to  fouthf 
and  its  greateft  length  in  that  diredtion  falls  very  little  (hort  of  three  miles.  Its  breadth^ 
varies  with  the  indentations  of  the  fhore,  but  it  no  where  exceeds  three  quarters  of  a  mile. 
The  line  of  its  ridge  is  undulated,  and  the  two  extremes  are  fomewhat  higher  than  its 
centre. 

The  fummit  of  the  Sugar-loaf,  which  is  the  point  of  its  greateft  elevation  towards  the 
fouth,  is  1439  f^^^ »  ^^^  Rock  Mortar,  which  is  the  highcft  point  to  the  north,  is  1 350  ;  and 
the  Signal-houfe,  which  is  nearly  the  central  point  between  thefe  two,  is  1276  feet  above  the 
level  of  the  fea.  The  weftern  fide  of  ths  mountain  is  a  feries  of  rugged  flopes,  interfperfed 
with  abrupt  precipices.  Its  northern  extremity  is  perfedlly  perpendicular,  except  towards 
the  north-weft,  where  what  are  called  the  Lines  intervene,  and  a  narrow  paffage  of  flat 
•  Tranfaftions  of  the  Royal  Society  of  Edinburgh,  iv,  191. 

Vol.  IL—Julv  1798.  B  b  ground 


'1 96  Minerahg'ical  Defcr'iption  of  Gibraltar. 

ground  that  leads  to  the  jilhrnus,  and  is  entirely  covered  with  fortification.  The  eaftern 
fide  of  the  mountain  raoftly  confifts  of  .a  range  of  precipices  j  but  a  bank  of  fand  rifing  from 
the  Mediterranean  in  a  rapid  acclivity  covers  a  thii:d  of  its  perpendicular  height.  Its 
fouthern  extremity  falls  in  a  rapid  flope  from  the  fuinmit  of  the  Sagai-loaf  into  a  rocky  flat 
of  confu'erable  extent  called  Windmill-hill.  This,  flat  forms  half  an  oval,  and  is  bounded  by 
a  ifange  of  precipices,  at  the  fouthe^in  bafe  of  which  a  fccond  rocky  fiat  takes  place  fimilar  in 
form  and  extent  to  Windmill-hill ;  and  alfo  like  it  furrounded  by  a  precipice,  the  fouthern 
extremity  of  which  is  waflied  by  the  fea,  and  forms  Kuropa  Point,  Upon  the  weflern  fide 
this  peninfular  mountain  is  bounded  by  the  bay  of  Gibraltar,  which  is  in  length  nearly  eight 
miles  and  a  half,  and  in  breadth  upwards  of  five  milef.  In  this  bay  the  tide  frequently  rif.:s 
■  four  feet.  Upon  the  rforth  the  mountain  is  attached  to  Spain  by  a  low  fandy  ifthmus,  the 
grcatcft  elevation  of  which  above  the  level  of  the  fea  does  not  exceed  ten  feet,  and  its 
breadth  at  the  bafe  of  the  rock  is  not  more  than  three  quarters  of  a  mile.  This  ifthmus 
fcpaiatcs  the  Mediterranean  on  the  eaft  from  the  bay  of  Gibraltar  on  the  weft. 

This  mountain  is  tnuch  more  curious  in  its  botanical  than  in  its  mineralogical  productions. 
In  refpe£l  to  the  firft,  it  conne£ls  in  fome  degree  the  Flora  of  Africa  with  that  of  Europe. 
In  refpeft  to  the  latter,  it  produces  little  variety  ;  perhaps,  a  few  fubftances  and  phenomena 
that  are  rare,  but  none  that  are  peculiar. 

The  principal  mafs  of  the  mountain  rock  confifts  of  a  grey  denfe  (what  is  generally  called 
primary)  marble;  the  different  beds  of  which  are  to  be  examined  in  a  face  of  1350  feet  of 
perpendicular  height,  which  it  prefents  to  Spain  in  a  conical  form.  Thefe  beds  or  ftrata 
are  of  various  thicknefs,  from  20  to  upwards  of  40  feet,  dipping  in  a  dire£lion  from  eaft  t* 
weft  nearly  at  an  angle  of  35  degrees.  In  fome  parts  of  the  folid  mafs  of  this  rock  I  have 
found  teftaceous  bodies  entirely  tranfmuted  into  the  conftituent  matter  of  the  rock,  and  their 
interior  hollows  filled  up  with  calcareous  fpar ;  but  thefe  do  not  occur  often  in  its  compofi- 
tion,  and  its  beds  are  not  fcparated  by  any  intermediate  ftrata. 

In  all  parts  of  the  globe  where  this  fpecies  of  rock  conftitutes  large  diftri£ls,  it  is  found 
to  be  cavernous.  The  caves  of  Gibraltar  are  many,  and  fome  of  them  of  great  extent. 
That  which  moft  deferves  attention  and  examination  is  called  St.  Michael's  Cave,  which  is 
fituated  upon  the  fouthern  part  of  the  mountain,  almoft  equally  diftant  from  the  Signal-tower 
and  the  Sugar-loaf  Its  entrance  is  loco  feet  above  the  level  of  the  fea :  this  entrance  is 
formed  by  a  rapid  flope  of  earth  which  has  fallen  into  it  at  various  periods,  and  which  leads 
to  a  fpacious  hall  incrufted  with  fpar,  and  apparently  fupported  in  the  centre  by  a  large  mafly 
ftalaftitical  pillar.  To  this  fucceeds  a  long  feries  of  caves  of  difficult  accef^.  The  paffages 
•from  the  one  to  the  other  of  thefe  are  over  precipices,  which  can  only  be  pafted  by  the  aflift- 
ance  of  ropes  and  fcaling-ladders.  I  have  myfelf  pafted  over  many  of  thefe  to  the  depth  of 
300  feet  frorn  the  upper  cave  j  but  at  that  depth  the  fmoke  of  our  torches  became  fo  difagree- 
able  that  we  were  obliged  to  give  up  our  purfuit,  and  leave  caves  ftill  under  us  unexamined. 
In  thefe  cavernous  recefles,  the  formation  and  procefs  of  ftaladlites  is  to  be  traced  from  the 
fiimfy  quilt-like  cone,  fufpended  from  the  roof,  to  tiie  robuft  trunk  of  a  pillar,  three  feet  in 
diameter,  which  rifes  from  the  floor,  and  feems  intended  by  nature  to  fupport  the  roof  from 
which  it  originated. 

The  variety  of  form  which  this  matter  takes  in  its  different  fituations  and  direflions  renders 
this  fubterraneous  fcenery  ftrikijigly  grotefque,  and  in  fome  places  beautifully  picfturefque. 

The 


Minerali^leal  Defcrlpt'wn  of  Cihrahaf,  jij 

The  ftalaftites  of  thcfe  caves  when  near  the  furface  of  the  moiintain  are  of  a  brownlfli  yellow 
colour ;  but  as  we  defccnded  towards  the  lower  caves  we  found  them  begin  to  lofe  their 
darknefs  of  colour,  which  by  degrees  fhaded  off  to  a  whiiifti  yellow. 

The  only  inhabitants  of  thefe  caves  are  bats,  fome  of  which  are  of  a  large  fize.  The  foil 
in  general  upon  the  mountain  of  Gibraltar  is  but  thinly  fown ;  and  in  many  parts  that  thin 
covering  has  been  waflied  off  by  the  heavy  autumnal  rains,  which  have  left  tha  fuperficies 
of  the  rock  for  a  confiderable  extent  bare  and  open  to  infpedlion.  In  thoft  fituations  an 
obferving  eye  may  trace  the  effefts  of  the  flow  but  cotiftant  decompofition  of  the  rock,  caufed 
by  its  expofure  to  the  air,  and  the  corrofion  of  fea  falts,  which  in  the  heavy  gales  of  eafter- 
ly  winds  are  depofited  with  the  fpray  on  every  part  of  the  mountain.  Thofe  uncovered  parts 
of  the  mountain  rock  alfo  expofe  to  the  eye  a  phenomenon  v7orthy  of  fome  attention,  as  it 
tends  clearly  to  demonftrate,  that,  however  high  the  furface  of  this  rock  may  now  be  elevated 
above  the  level  of  the  fea,  it  has  once  been  the  bed  of  agitated  waters.  This  phenomenon 
is  to  be  obferved  in  many  parts  of  the  rock,  and  is  conftantly  found  in  the  beds  of  torrents. 
It  confifts  of  pot-like  holes  of  various  fizes  hollowed  out  of  the  folid  rock,  and  formed  ap- 
parently by  the  attrition  of  gravel  or  pebbles  fet  in  motion  by  the  rapidity  of  rivers  or  currents 
in  the  fea'.  One  of  thofe,  which  had  been  recently  laid  open,  I  examined  with  attention.  I 
found  it  to  be  five  feet  deep  and  three  feet  in  diameter ;  the  edge  of  its  mouth  rounded  ofFas 
if  by  art,  and  its  fides  and  bottom  retaining  a  confiderable  degree  of  polifli.  From  its  mouth 
ibr  three  feet  and  a  half  down  it  was  filled  with  a  red  argillaceous  earth,  thinly  mixed  with 
minute  parts  of  tranfparent  quartz  cryflials :  the  remaining  foot  and  a  half'to  the  bottom 
contained  an  aggregate  of  water-worn  (tones,  which  were  from  the  fize  of  a  goofe's  egg  to^ 
that  of  a  fmall  walnut,  and  confided  of  red  jafpers,  yellowifh  white  flints,  white  quartz,  and 
blueilh  white  agates,  firmly  combined  by  a  ycllowifh  brown  ftaladlitical  calcareous  fpar.  la 
this  breccia  I  could  not  difcover  any  fragment  of  the  mountain  rock,  or  any  other  calcareous 
matter,  except  the  cement  with  which  it  was  combined.  This  pot  is  940  feet  above  the 
level  of  the  fea. 

Upon  the  weft  fide  of  the  mountain  towards  its  bafe  fome  ftrata  occur,  which  are  hete- 
rogenial  to  the  mountain  rock  :  the  firfl;  or  highefl  forms  the  fcgment  of  a  circle  j  its  con- 
vex fide  is  towards  the  mountain,  and  its  flopes  alfo  in  that  direiSlion.  This  ftratum  confifts 
of  a  number  of  thin  beds  ;  the  outward  one,  being  the  thinneft,  is  in  a  fl:ate  of  decompofition, 
and  is  mouldering  down  into  a  blackifh  brown  or  ferruginous  coloured  earth.  The  beds 
inferior  to  this  progreflively  increafe  in  breadth  to  17  inches,  where  the  flratification  refts 
upon  a  rock  of  an  argillaceous  nature. 

This  laft  bed,  which  is  17  inches  thick,  confifls  of  quartz  cf  a  blackifh  blue  colour,  in 
the  fepta  or  cracks  of  which  are  found  fine  quartz  cryftals,  colourlefs  and  perfedlly  tranf- 
parent. Thefe  cryftals  are  compofed  of  18  planes,  difpofed  in  hexangular  columns,  termi- 
nated at  both  extremities  by  hexangular  pyramids.  The  largeft  of  thofe  that  I  have  feen 
does  not  exceed  two-eighths  of  an  inch  in  length  :  they  in  general  adhere  to  the  rock  by  the 
fides  of  the  column,  but  are  detached  without  difficulty.  Their  great  degree  of  tranfparency 
has  obtained  them  the  name  of  Gibraltar  diamonds. 

[To  be  continued.'] 

Bb2  JG. 


l88  Nev)  Puhlicatlonf. 

ACCOUNT  OF   NEIV  BOOKS. 

Memoirs  of  the  Literary  and  Philofophical  Society  of  Manchefter,  Vol.  V.  Part  I.  8vo, 
318  pages,  with  four  plates.  Price  6  (hillings  in  boards.  Cadell  and  Davies,  London, 
1798. 

X  HIS  volume  contains,  I.  Ciirfory  Remarks,  moral  and  political,  on  Party  Prejudice. 
By  Saniuel  Argent  Bardfley,  M.  I). — 2.  Extraordinary  Fads  relating  to  the  Vifion  of  Co- 
lours; with  Obfervations.  By  Mr.  John  Dalton.  The  intelligent  author  of  this  valuable 
paper  is  himfelf  the  fubjeit  of  many  of  his  obfervations  refpecling  the  peculiarity  of  his  per- 
ceptions of  colours.  This  Memoir  confifts  of  an  account  of  his  own  vifion  ;  an  account  of 
others  whofe  vifion  has  been  found  fimilar  to  his  ownj  and  obfervations  refpedling  the 
probable  caufe  of  the  peculiarities  he  defcribes.  The  folar  fpedrum,  formed  by  the  prifma- 
tic  difperfion  of  light,  exhibits  to  him  only  two,  or  at  moft  three,  colours,  which  he  fliould 
call  yellow  and  blue,  or  yellow,  blue,  and  purple.  This  yellow  comprehends  the  red, 
orange,  yellow,  and  green  of  others  ;  and  his  blue  and  purple  coincide  with  theirs.  He 
enters  minutely  into  the  requifite  comparative  obfervations  on  the  feveral  colours  refpeft- 
ively  as  they  afFeft  his  organs  of  fight.  Pink  appears,  by  day-light,  to  be  fky-blue  a  little 
faded  ;  by  candle-light  it  affumes  an  orange  or  yellowifh  appearance,  which  forms  a  ftrong 
contrail  to  blue.  Crimfon  appears  a  muddy  blue  by  day  ;  and  crimfon  woollen  yarn  is 
much  the  fame  as  dark  blue.  Red  and  fcarlet  have  a  more  vivid  and  flaming  appearance 
by  candle-light  than  by  day-light.  There  is  not  much  difference  in  colour  between  a  ftick 
of  red  fealing-wax  and  grafs  by  day.  Dark  green  woollen  cloth  feems  a  muddy  red,  much 
darker  than  grafs,  and  of  a  very  different  colour.  The  colour  of  a  florid  complexion  is 
dufky  blue.  Coats,  gowns,  &c.  appear  to  Mr.  Dalton,  and  the  other  individuals  he  men- 
tions, frequently  to  be  badly  matched  with  linings,  when  others  fay  they  are  not.  On  the 
other  hand,  they  fhould  match  crimfons  with  claret  or  mud  ;  pinks  with  light  blues  ;  browns 
with  reds  ;  and  drabs  with  greens.  In  all  points  where  they  differ  from  other  perfons,  the 
difference  is  much  lefs  by  candle-light  than  by  day-light.  Mr.  Dalton,  by  various  obferva- 
tions, fhews,  almoft  beyond  a  doubt,  that  this  afFe£lion  of  the  eye  is  caufcd  by  fomeofthe 
humours,' probably  the  vitreous,  being  coloured  by  fome  modification  of  blue. — 3.  An  En- 
quiry into  the  Name  of  the  Founder  of  Huln  Abbey,  Northumberland,  the  firfl  in  England 
of  the  Order  of  Carmelites ;  with  Remarks  on  Dr.  Ferriar's  Account  of  the  Monument  in 
the  Church  of  that  Monaflery.  By  Robert  Uvedale,  B.  A.  of  Trinity  College,  Cambridge. — 
4.  On  the  Variety  of  Voices.  By  Mr.  John  Gough.  It  is  a  fadt  which  continually  prefents 
jtfelf  to  our  obfervation,  that  founds  differ  from  each  other  in  other  refpedls  as  well  as  in 
mufical  tone  and  their  intenfity.  The  oboe,  the  violin,  and  the  flute,  however  perfedly  they 
maybe  made  to  agree  in  thefe  refpcfts,  are  ever  found  to  differ  in  fomething  which  may  be 
called  the  charader  of  the  tone  itfelf.  The  author  of  this  paper  conceives  that  the  variety 
of  human  voices  is  of  this  laft  kind  ;  and,  in  his  reafoning  on  the  philofophy  of  found,  he 
confiders  every  tone  as  compounded.  So  that  the  fame  cotemporaneous  founds  which  are 
heard  in  the  bell,  though  praflically  confidered  as  if  it  emitted  the  fundamental  note  only, 
being  conceived  to  exift  in  all  other  tones,  thefe  will  be  found  to  differ  according  to  the 
number,  the  nature  or  relation,  and  the  intenfity  of  their  component  parts.    That  circum- 

ftances 


Nfw  Publications,  lgg> 

ftances  of  this  kind  may  modify  the  aggregate  of  fonorous  undulation,  is  ftarcely  to  be 
doubted ;  but  Mr.   Gough  feems  to  have  overlooked  that  modification,  which  may  be 
proved  to  be  the  diftinguifliing  circumftance  between  tone  and  tone  when  they  are  in 
unifon.     If  a  toothed  wheel  be  made  to  revolve  very  fwiftly  with  its  teeth  againft  a  fpring, 
lyhich  fliall  ftrike  each  tooth  in  fucceflion,  a  mufical  tone  will  be  produced,  which  will  be 
more  acute  the  fwifter  the  rotation.     But  this  tone  will  differ  accordingly  as  the  material 
of  the  wheel  is  itfelf  difpofed  to  give  a  tone  of  greater  acutenefs  or  gravity  by  each  fingle  or 
individual  ftrokc.     If  the  fame  note  be  afforded  by  a  brafs  and  by  a  wooden  wheel  revolv- 
ing on  one  axis,  the  charadler  of  each  note  will  differ  in  the  manner  here  flated.     Or 
more  fimply,  if  a  cord  of  thirty  or  forty  feet  in  length,  or  Ihorter  if  more  convenient,  be 
ftretched,  and  in  this  ftate  flruck  with  the  edge  of  the  hand,  the  vibrations  will  be  flow 
enough  to  be  counted,  and  will  evidently  appear  to  be  of  two  kinds.     When  the  firing  is 
ftruck  near  the  end  or  bridge,  a  wave  or  undulation  will  be  propagated  to  the  other  bridge, 
and  immediately  return;  which  procefs  will  continue  as  long  as  the  elafticity  of  the  firing 
can  maintain  the  motion.     The  waves  of  this  undulation  will  be  larger  or  fmaller,  the  more 
remote  or  the  nearer  the  place  of  percufTion  is  to  the  bridge  ;  but  the  times  of  tranfmilTtoa 
of  the  waves  backwards  and  forwards  along  the  firing  will  be  invariable.     The  tone  of 
fuch  a  firing,  fuppofing  its  dimenfions  and  tenfion  to  be  fuch  as  would  produce  found,  may 
therefore  be  confidered  as  if  the  tone  produced  by  the  fyflem  of  waves  were  interrupted  as- 
often  as  the  re-a6lion  of  each  bridge  caufes  the  retrograde  motion  of  the  fyflem;  that  is  to  fay, 
it  is  afforded  by  a  procefs  fimilar  to  that  of  the  experiment  with  the  wheels,  where  the  peculiar 
found  of  a  blow  upon  each  tooth  was  incefPantly  repeated  and  fufpended  at  regular  intervals. 
Now,  the  mufical  acutenefs  or  gravity  of  the  tone  depends  altogether  on  the  time  of  thefe 
intervals,  and  not  at  all  on  the  nature  of  the  found  which  is  thus  repeated  ;  but  the  cha- 
radler  of  the  tone  is  governed  by  this  lafl  circumilance.     i\nd  accordingly  it  is  found  by 
thofe  who  make  harpfichords,  and  other  fimilar  inflruments,  that  the  chara<Sler  of  the  tone 
of  the  fame  firing  is  wonderfully  changed,  accordingly  as  the  jacks  or  hammers  are  made 
to  operate  nearer  to,  or  further  from,  the  bridge. — 5.  On  the  Benefits  and  Duties  refulting 
from  the  Inflitution  of  Societies  for  the  Advancement  of  Literature  and  Philofophy.  By  the 
Reverend  Thomas  Gifborne,  M.  A. — 6.  On  an  Univerfal  Chara(2;er.   By  James  Anderfon, 
LL.D.  F.R.S.  &c.     By  this  letter,  which  bears  date  February  20,  1795,  it  appears  that 
the  Doftor  had  then  made  confiderable  progrefs  in  the  invefligation  of  the  means  of  writ- 
ing language   by  chara£lers   regularly  conflrudled  on  thofe  principles  of  iivental  operation 
which  conftitute  univerfal  grammar,   and   do  not  require  the  intervention  of  found.     To 
thofe  who  have  confidered  this  fubje£l,  particularly  with  refpeil  to  the  praflice  of  the  Cbi- 
nefe,  whofe  written  words   are  known  to  reprefent,   for  the  mofl  part,   things   infbead  of 
words,  and  confequently  are  intelligible  to  nations  who  do  not  fpeak  the  fame  language,  the 
prafticability  of  this  fcheme  will  be  a  matter  of  no  doubt.     But  whether  the  difficulties  be 
fuch  as  to  operate  more  ftrongly  againft  its  introdudlion  in  Europe  than  the  immediate  mo- 
tives of  convenience  in  favour  of  its  reception,  is  a  queflion  which  can  only  be  decided  by 
minute  and  continued  attention  to  the  whole  fubjeft.     That  thefe  difficultie-  are  compara- 
tively fmall,  and  would  yield  to  the  induflry  of  aftive  and  intelligent  men,  in  the  firft  in- 
flance,  is  fcarcely  to  'ie  doubted,  provided  the  exertions  of  the  firft  promoters  of  this  fcheme 
were  carried  fo  far  as  to  afford  a  grammar,  a  didionary,  and  one  or  two  well  written  intro- 

duftory 


f^  2^eiv  Puhlicaiions. 

duflofy  lioofc$  on  morals,  poHtical  economy,  or  the  more  confined  fciences  of  mechanic?, 
chemiftry,  or  aftronomy.     The  facility  and  accuracy  of  enunciation,  the  fpeed  and  brevity 
of  defcription,  "and  the  extreme  rapidity  of  perufa!,  would   foon   realize   thofe   expefta- 
tions  upon  which  our  author  and  a  few  men   of  refle£tion   now  meditate  as   the    objeds 
of  enjoyment  deftined  for  remote  future  ages.     The  Doftor  has  not  entered  into  the  parti- 
culars of  his  own  fcheme  ;  and  the  prefent  occafion  xloes  not  admit  of  a  detail  of  the  multi-  ' 
plied  means  and  advantages  which  prefent  themfelves  fn  the  contemplation  of  this  intereft-' 
ing  fubjeft.    From  the  date  of  his  letter,  it  is  to  be  feared   that  other  avocations  may  have 
fufpended  this  purfuit,  as  well  on   his  own  pa^t  as  that  of  his  able  friend  whom  he  men- 
tions as  being  aiSlively  engaged  in  it. — 7.  The  Inverfe  Method  of  Central  Forces.    Commu- 
nicated by  Dr.  Holme.— 8.  Obfervations  on  Iron  and  Steel.     By  Jofeph  Collier.     After  a 
-  concife  account  of  the  methods  of  fmelting  and  refining  iron,  a  defcription  is  given  of 
the  manufacture  of  fteel  by  cemeiitation,-  with  a  good  drawing  exhibiting  the  plan  and  fee-  '■ 
tion  of  a  furnace  for  performing  this  operation.     I  do  not  recoliedl:  meeting  with  a  draw-  • 
ing  of  this  kind  in   any   Englifli  author.     Mr.  Collier's  paper  exhibits  a  fummary  of  the  ■ 
mofl  effential  fa£ls  related  by  Reaumur,  Duhamel,  Vandermonde,  Monge,  and  Berthollet,  ■ 
and  others*.— 9.  Remarks  on  Dr.  Prieflley's  Experiments  and  Obfervations  relating  to  the  . 
Analyfis  of  Atmofpherical  Air,  and  his  Confiderations  on  the  Dodirine  of  Phlogifton  and  the 
Decompofition  of  Water.    By  Theophilus  Lewis  Rupp.     The  modern  chemiftry  which  re- 
jefts  phlogifton  is  ably  defended  in  this  paper,  of  which,  from  the  clofe  method  of  quotation 
and  remark  according  to  which  it  is  written,  it  is  impoffible  to  give  any  fair  account  in  this 
place. — 10.  An  Accountof  three  different  Kinds  of  Timber  Trees,  which  are  likely  to  prove 
a  great  Acquifition  to  this  Kingdom,  both  in  point  of  Profit,  and  as  Trees  for  Ornament 
and  Shade.    By  Charles  White,  Efq.  F.R.S.    The  trees  are  the  black  American  birch  with 
broad  leaves,  the  Athenian  poplar,  and  the  iron  oak  with  prickly  cups.     For  the  minute 
particulars  of  defcription,  as  well  as  the  perfpicuous  detail  of  advantages,  recourfe  muft  be 
had  to  the  paper  itfelf. — 1 1.  An  Analyfis  of  the  Waters  of  two  Mineral  Springs  at  Leming-  , 
ton  Priors,  near  Warwick,  including  Experiments  tending  to  elucidate  the  Origin  of  the 
^luriatic   Acid.    By  William  Lambe,  M.  A.   late   Fellow  of  St.  John's  College,   Cam- 
bridge.—12.   Some  Account  of  the  Perfian  Cotton  Tree.    By  Matthew  Guthrie,  M.D. 
F.R.S.    &c.  —  13.  Experiments    and   Obfervations    on   the   Preparation    and   fome    re- 
markable Properties  of  the  Oxygenated  Muriate  of  Potafh.     By  Thomas  Hoyle,  jun.— . 
14.  Experiments  and  Obfervations  on  Fermentation  and  the  Diftillation  of  Ardent  Spirit. 
By  Jofeph  Collier.  On  the  chemical  papers  laft  mentioned,  as  well  as  the  fubfequent  paper  on 
bleaching,  I  make  no  remarks,  not  only  for  the  fake  of  brevity,  but  becaufe  I  hope  on  a  future 
occafion  to  give  a  more  ampleaccount  of  their  contents. — 15.  Hints  on  the  Eftabliftimentof 
an  Univerfal  Written  Charafter.  By  William  Brown,  M.D.  Notwithftanding  the  great  value  , 
of  this  paper,  and  the  ability  of  its  author,  who  has  occafionally  turned  his  thoughts  during 
three  years  to  Dr.  Anderfon's  projeif,  I  cannot  help  wiftiing  that  he  may  not  be  the  friend 
to  whom  that  author  refers.     His  hints  contain  an  outline  of  the  procefs  by  which  an  univer- 
fal written  charader  is  to  be  eftablifhcd  j  but  he  feems  rather  difpofed  to  confider  the  pro- 

•  The  author  mentions  certain  omiffions  in  my  Chemical  Diftionary,  article  Iron,  which  he  would  have 
found  under  the  word  Steel,  if  he  had  turned  te  that  article; 

jea 


New  Pullkatm!,  }A| 

jeft  as  being  very  laborious,  and  in  its  praftical  application  difficult  to  be  eftabliflied. 
Under  fuch  impreffions,  much  is  not  to  be  expe£led  in  the  progrcfs.  It  feems  neverthelefs  that 
mankind  have  rejeded  univerfal  charaders  when  offered  to  them,  not  becaufe  they  were 
averfe  from  the  means  of  facility  and  perfpicuity,  but  becaufe  thofe  means  were  not  in  reality 
difpUyed.     The  Arabic  numerals,  the  notation  pf  mufic,  and   the  fymbols  of  quantity  and 
operation  ufed  by  algcbrai/ls,  are  univerfal  charadters  confined  to  no  language,  and  have  been 
univerfally  received  becaufe  they  are  fimple  and  appropriate  ;  but  the  charafters  of  chemifts, 
as  well  as  the  few  attempts  at  the  more  ample  defignation  of  things  in  the  fame  manner, 
have  not  been  received,  becaufe  their  authors  have  {topped  fhort  in  their  ufe  and  adaptation. 
If  Bifhop  Willcins,  and  the  great  men  of  the  laft  century  who  favoured  his  univerfal  cha-^ 
ra<Sler,  had  ftudied  and  ufed  it  to  fuch  an  extent  as  to  have  written  treatifes  according  to  that 
notation  ;  or  if  the  great  Bergman  had  attempted  a  reform  in  the  charaflers  of  chemiftry, 
and  adopted  fuch  as  could  be  readily  formed,  eafily  diflinguifhed,  and  compounded,  with  all 
the  advantages  of  pofition,  of  which  he  was  fo  well  aware }  if  he  had  completed   a  fet  of 
tables  exhibiting  the  whole  of  chemical  fcience,  and  e.xpreffing  things,  quantities,  adtions,. 
temperatures,  and  other  habitudes,  in  a  few  pages,  which  thofe  who  attentively  meditate 
on  his  compound  tables  of/eleiSlive  attraftion  may  without  difficulty  conceive  to  be  polBble  j 
the  lovers  of  that  fcience  would  have  learned  to  read  his  work,  and  to  write  others  accord- 
ing to  the  fame  method;  and  that  for  reafons  of  the  fame  kind  as  have  induced  arithmeti- 
cians, muficians,  and  algebraifts,  to  become  mailers  of  the  univerfal  charaders  proper  to  theif 
refpeftive  fciences. — 16.  On  the  Procefs  of  Bleaching  with  the  Oxygenated  Muriatic  Acid, 
and  a  Defcription  of  a  new  Apparatus  for  Bleaching  Cloths  with  that  Acid  diffolved  in  Water 
without  the  Addition  of  Alkali.    By  Theophilus  Lev/is  Rupp. — 17.  Account  of  a  remarkable 
Change  of  Colour  in  a  Negro.    By  Miers  Fifher.    This  man's  father  was  the  fon  of-  a  native 
African  and  an  Indian  of  Philadelphia.    His  mother  was  the  daughter  of  an  African  man 
and  an  Irifli  woman.     By  a  certificate  here  exhibited,  it  appears,  that  until  the  month  of 
February    1792,  being  then  at  leaft  30  years  old,  he  was  of  as  dark  a  complexion  as  any 
African;  at  which  period  his  fkin  began  to  change  white,  like  that  of  an  European,  com- 
mencing at  his  fingers'  ends,  and  proceeding,  chiefly  in  the  fummer  or  warm  weather,  over 
the  reft  of  his  body.     The  greater  part  of  the  furface  was  thus  changed  at  the  time  of  the  ac- 
count being  written,  which  was  the  I'lA  of  November  1796.     The  change  was  not  uniform 
over  the  whole  furface,  but  gradually  progreffive  along  the  fkin ;  the  black  and  white  parts 
being  feparated  by  an  irregular  line.     No  faifls  are  mentioned  in  explanation  of  this  re- 
markable change.  ■.  .  .  . 

Tranfatlions  of  the  Royal  Society  of  Edinburgh,  Vol.  IV.    Quarto.     470  pages,  with  12 

plates.     Printed  for  Cadell  and  Davies  in  London  j  and  Dixon  and  Balfour,  Edinburgh. 

1798. 

This  work  is  divided  into  three  parts. 

Part  I.  contains  the  Hiflory  of  .the  Society,  or  Reports  concerning  Memoirs  prefented, 
and  Communications  made,  with  a  Lift  of  the  Officers  and  Members,  Donations,  and  other 
fimilar  Particulars.    It  alfo  contai-    Biographical  Accounts  of  Lord  Abercromby  ;   ofWil-- 
liam  Tytler,  Efq.  of  Woodhoufelee  ;  of  Mr.  William  Hamilton,  late  ProfefTor  of  Anatomy 
and  Botany  in  the  Univerfity  of  Glafgow  5  and  of  John  Roebuck,  M,  D. 

Part  II. 


lijjl'  ^ew  Pullicat'tons, 

Part  II.  contains,  I.  Papers  of  the  Phyfical  Clafs. — I.  Accountof  a  Mineral  from  Strontian, 
and  of  a  peculiar  Species  of  Earth  which  it  contains.    By  Thomas  Charles  Hope,  Profeffor* 
of  Medicine  in  the  Univerfity  of  G1afgow.~2.  Obfervations  on  the  Natural  Hiftory  of 
Guiana.     By  William  Lochead,  E<q. — 3.  On  the  Principles  of  the  Antecedental  Calculus. 
By  James  Glenie,  Efq. — 4.  Obfervations  on  the  Trigonometrical  Tables  of  the  Brahmins. 
By  John   Playfair,  Profeflbr  of  Mathematics   in  the  Univerfity  of  Edinburgh. — 5.  Soma 
Geometrical  Porifms,  with  Examples  of  their  Application  to  the  Solution  of  Problems.    By 
Mr.  William  Wallace,  Afliftant  Teacher  of  the  Mathematics  in  the  Academy  of  Perth. — 
5t.  On  the  Latitude  and  Longitude  of  Aberdeen.     By   Andrew  Maclcay,  LL.D.  &F.R.S. 
Edin. — 6    An  Account  of  certain  Motions  which  fmall  lighted  Wicks  acquire  when  fwim- 
ming  on  a  Bafon  of  Oil.     By  Patrick  Wilfon,  F.R.S.  Edin,  and  Profeffor  of  Praftical 
Aftronomy  in  the  Univerfity  of  Glafgow.   (See  PhiloC  Journal,  II.  167.) — 7.  Account  of  a 
fingular  Halo  of  the  Moon.     By  William  Hall,  Efq.  of  Whitehall,  F.R.S.  Edin.— 8.  A 
New  Series  for  the  Redification  of  the  Ellipfis,  with  Obfervations  on  the  Evolution  of  a 
certain  Algebraic  Formula.     By  James  Ivory,  A.M.— 9.  Mineralogical  Defcription  of  the 
Mountain  of  Gibraltar.    By  Major  Imrie. — 10.  Defcription  of  a  Thermometer,  which  marks 
the  greateft  Degree  of  Heat  and  Cold  from  one  Time  of  Obfervation  to  another.    By  Alex- 
ander Keith,  Efq.  F.R.S.  &  F.A.S.  Edin. — 11.  Defcription  of  a  Barometer  which  marks 
the  Rife  and  Fall  of  the  Mercury  from  two  different  Times  of  Obfervation.    By  Alexander 
Keith,  Efq.  F.R.S.  &  F.A.S.  Edin.— 12.  Meteorological  Abftradfor  the  Years  1794, 1795, 

l^p(5. n.  Papers  of  the  Literary  Clafs.— i.  On  the  Origin  and  Principles  of  Gothic 

Architedure.  By  Sir  James  Hall,  Bart.  F.R.S.  &  A.S.S.  Edin.— 2.  M.  Chevalier's 
TableaudelaPlaine  deTroye  illuflrated  and  confirmed  from  the  Obfervations  of  fubfequent 
Travellers  and  others.  By  Andrew  Dalzel,  M.A.  F.R.S.  Edin.  Profeffor  of  Greek  in 
Ihe  Univerfity  of  Edinburgh. 

•  Now  Joint  ProfeiTor  of  Chemiftry  in  the  Univerfity  of  Edinburgh. 
t  By  miftake,  No.  5.  is  repeated. 


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AUGUST    1798. 


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ARTICLE    L 

Farther  Experiments  and  Obfervations  en  the  JJ'eEliont  and  Properties  of  Li^ht, 
By  HENsr  Brougham,  jun.  Efq. 

[Concluded  from  Page  155  of  the  prefent  Volume.] 
Oltfervatim  5. 

H  E  direfl:  light  falling  on  the  fpeculum,  and  part  of  the  reflected  light  on  the  horizontal 
white  ftage  of  a  very  accurate  micrometer,  I  meafured  the  breadth  of  the  fringes,  fpots,  &c. 
Thefe,  with  the  diftance  of  the  fpeculum  from  the  window  and  micrometer,  and  the  fizc  o£ 
the  fun's  image,  are  fet  down  in  the  following  table,  all  reduced  to  inches  and  decimals. 

Inches.  Parts. 
Diftance  of  the  fpeculum  from  the  bole  in  the  window  fliut  -  -  24. 

Diftance  of  the  fpeculum  from  the  flage  of  the  micrometer  -  -  18. 

TrarWverfe  axis  of  the  fun's  image  .  «  -  .  2. (J 

Conjugate  axis  of  the  fun's  image  -  -  -  «  1. 4 

Length  of  the  oblong  dark  fpot  •  -  »  -  •+   , 

Breadth  of  the  oblong  dark  fpot  »  -  _  -  '0074.,   ^ 

Breadth  of  its  firft  fringe  »  •  -  -  .0022  •   • 

Elliptic  fpot's  tranfverfe  axis  ;  -  -  .0016 

• conjugate  axis  i  •  -  -  .0068 

Breadth  of  its  firft  fringe  •  -  •  'Ofij^ 

Tranfverfe  axis  of  a  larger  elliptic  fpot  -  -  -  .013 

Conjugate  axis  of  the  fame  fpot  »  »  •   '  .OO76 

Vol.  IL— August  1798.  C  c  I|k 


iy4  O"  '^'  Prgperttf!  tf  Light.— 'Colours  Jram  Specula^ 

In  the  image  whers  thefe  meafures  were  taken,  there  were  feven  other  elllpflc  fpots,  3 
little  lefs  and  nearly  equal ;  all  the  others  were  much  fmaller  and  more  confufed. 

Obfervation  6.  On  viewing  the  furface  of  the  fpeculum  attentively  in  thit  place  whence 
the  rays  formed  the  oblong  and  firft  mentioned  elliptic  fpots,  I  faw  a  dark  but  very  thin  long 
fcratch,  and  a  dark  dent,  fimilar  in  (hape  to  the  dark  fpaces- on  the  image  i  the  dark  fpot 
meafurcd  lefs  than  -^\-^  oi  an  inch  ;  which  mukcs  its  whole  fur£ice  to  the  whole  polifheJ 
furface,  as  i  to  342251  fuppofing  the  former  circular  or  nearly  fo.  All  thefe  meafures  will 
be  found  to  agree  very  well,  for  their  fmallnefs  and  delicacy:  thus,  the  ratio  laft  mentioned 
is  nearly  the  fame  which  we  obtain  by  comparing  the  image  and  the  fpot:  the  like  may  be 
faid  of  the  two  fpots  mentioned  in  the  table,  i.  e.  their  axes  are  proportional.  I  now  could 
produce  what  fpots  I  pleafed,  by  gently  fcratching  the  fpeculum,  or  by  making  lines,  dots, 
&c.  with  ink,  and  allowing  it  to  dry;  for  thefe  laft  formed  convex  fibres,  which  produced 
coloured  fringes  as  well  as  the  concavities,  agreeably  to  what  was  deduced  a  priori. 

Obfervation  7.  The  whole  appearajice  \yhich  I  have  been  defcribing  bore  fuch  a  clofe 
and  complete  refemblance  to  the  fringes  raa<le  round  the  (badows  of  bodies,  that  the  identity 
of  the  caufe  in  both  cafes  could  not  be  doubted,  ^n  order,  however,  to  fliew  it  ftill  further, 
I  meafured  the  breadths  of  two  contiguous  fringes  in  feveral  different  fets :  the  meafure- 
ments  agreed  very  well,  and  gave  the  breadth  of  the  firft  fringe  .0056,  and  of  the  fecond 
.0034  ;  or  of  the  firft  .0066,  and  of  the  fecond  ^0034.  The  ratio  of  the  breadths  by  the  firft 
is  28  to  17  ;  by  the  fecond,  30  to  17;  of  which  the  medium  is  29  to  17  :  and  this  is  precifely 
the  ratio  of  the  two  innermoft  fringes  made  by  a  "hair,  according  to  Sir  Ifaac  Newton's  mea- 
JTurement ;  the  firft  being,  according  to  him,  ~o  of  an  inch  j  the  fecond,  ^^  of  an  inch  *. 
Farther,  the  two  innermoft  rings  made  by  plates  have  their  diameters  (not  breadths)  in  the 
r.atio  of  I  fi-  to  2  if,  and  the  diflance  between  the  middle  ©f  the  innermoft  fringes  (made  by 
a  hair),  on  either  ilde  the  ftiadow,  is  to  the  fame  diftance  in  the  fecond  fringes  as  3-^  to ^j-  ^ 
therefore,  the  diameters  of  the  two  firft  rings  made  by  the  fpecks  in  the  fpeculum,  are  as 
^6?-  to  ttVt;  which  ratio  differs  exceedingly  little  from  that  of  i  fi  to  2  |,  the  ratio  of  the 
diameters  of  rings  made  by  plates,  either  thofe  called  by  Newton  thick,  or  thofe  which  he 
names  thin :  for  fuppofe  this  difference  nothing,  %\X  ^||  =  i fi  X  -jt-Vt >  and  the  differ- 
ence between  thefe  twoproduiils  (now  ftated  equal)  is  not  much  above  ^  in  reality. 

Obfervation  8.  The  laft  thing  worth  mentioning  in  thefe  phenomena  was  this  :  I  viewed, 
the  fringes  through  a  prifm,  holding  the  refracting  angle  upwards,  and  the  axis  parallel  to 
that  of  the  dark  fpace ;  then  moving  it  ti'l.  the  objefls  ceafed  defcending,  I  faw  in  that 
pofture  the  fringes  much  more  diftindt  and  numerous;  for  I  could  now  fee  five  with  eafe,  and 
feveral  more  lefs  diftinftly..  This  led  me  to  try  more  minutely  the  truth  of  the  5th  propofi- 
tion,  with  refpeft  to  the  nitmber  of  the  fringes  fiirroundlng  the  ihadows  of  bodies  in  diredl 
light.  Having  produced  a  bright  fet  of  thefe  by  a  blackened  pin  -^  of  an  inch  in  diameter, 
I  viewed  them  through  a  well  made  prifm,  whof®  refradling  angle  was  only  30°,  and  heli 
this  angle  upwarils,  when  the  fringes  were  on  the  fide  of  the  fhadow  oppofite  to  me.  1 
then  moved  the  prifm  round  on  its  axis ;  arid  when  it  was  in  the  pofture  between  the  afcend 
and  defcent  of  the  objefts,  Iwas  much  pfeafed  to  fee  five  fringes- plainly,  and  a  great  num- 
ber beyondj  decreafing  in  fize  and  brightnefs  till  they  became  too  fmall  and  confufed  for 

,   .  *  Of  tics,  book  iii.  obC.  y  -^  Book  ii,  parts  i  and  4, 

.9  fiS>»t, 


On  the  AffeBUns  af  Ligtit.—  Colour.t  from  specula,  ipj 

fight.  In  like  manner,  thofe  formed  by  a  double  flexion  of  two  bodies,  and  thofe  made  out 
of  homogeneal  light,  were  feen  to  a  much  greater  number  when  carefully  vkwed  througk 
the  prifm.  And  this  experiment  I  alfo  tried  with  all  the  fpecics  of  fringes  by  flexion  which  I 
could  think  of. 

Obfervation  9.  The  fame  appearances  which  were  occafioned  by  the  metal  fpeculum, 
might  be  naturally  expeflcd  to  appear  when  a  glafs  one  was  ufed.  But  I  alfo  found  the  like 
rings  or  fringes  of  colours  and  fpots  in  the  image  beyond  the  focus  of  a  lens  ;  nor  was  a  very 
excellent  one  belonging  to  a  Dollond's  telefcope  free  from  them,  'i'he  ringB  with  their  darfc 
intervals  refembled  thofe  floating  fpecics  fo  often  obferved  on  the  furface  of  the  eye,  and  call- 
ed "  mufcae  volitantes,"  only  that  the  mufcae  are  tranfparent  in  the  middle,  becaufe  formed 
by  drops  of  humor:  they  will,  however,  be  found  to  be  compaflTed  by  rings  of  faint  colours, 
which  will  become  exceedingly  vivid  if  the  eyes  be  fhut  and  flowly  opened  in  the  fun's  tight, 
fo  that  the  humor  may  be  coilefled  ;  they  alfo  appear  by  reflexion,  mixed  with  the  colour* 
defcribedin  Phil.  Tranf.  for  1796,  p.  268,  (or  Philof.  Journal  I.  593) 

Obfervation  10.  The  fun  (hining  ftrongly  on  the  concave  metal  fpeculum,  pliiced  at  fucH 
adillance  from  the  hole  in  the  window  that  it  was  wholly  covered  with  the  light ;  upon  in- 
clining it  a  little,  the  image  on  the  chart  was  bordered  on  the  infide  with  three  fringes 
iimilar  to  thofe  already  defcribed :  on  increafing  the  inclination  thefe  were-  diftended,  be  ■ 
coming  very  bright  and  beautiful :  when  the  inclination  was  great,  and  when  it  was  ftill  in-j 
creafed,  another  fct  of  colours  emerged  from  the  fide  next  the  fpeculum,  and  was  concive 
to  that  fide.  Her»  I  {lopped  the  motion,  and  the  image  on  both  fides  the  focus  had  three 
fets  of  fringes,  and  four  fringes  in  each  fet ;  but  when  viewed  through  a  prifm  (as  before 
defcribed),  the  numbers  greatly  increafed,  both  the  fringes  and  the  dark  intervals  decreafmj 
regularly.  The  appearance  to  the  naked  eye  is  reprefented  in  fig.  6,  plate  VII.  where  ADO 
being  the  image,  A  and  C  are  the  fets  of  fringes  at  the  edges,  and  li  the  third  fet,  there 
being  none  at  E  and  D  the  fides,  fince  the  light  which  illuminates  thefe  quarters  comes  not 
from  the  edges  of  the  fpeculum  in  fo  great  inclinations.  I  now  viewed  the  furface  of  the 
fpeculum,  and  faw  it  in  the  place  anfwering  to  B  in  the  image,  covered  with  fringes  exa6ily- 
correfponding  with  thofe  at  B }  and  on  changing  the  figure  of  that  part  of  the  fpeculum's 
edge  between  them  and  the  fun,  the  fringes  likewife  had  their  figure  altered  in  the  very  fame 
way.  On  moving  the  fpeculum  farther  round,  B  came  nearer  to  A  in  the  image,  according 
as  the  fringes  on  the  fpeculum  receded  from  that  fide  which  formed  them;  and  before  they 
vaniflied  alike  from  the  fpeculum  and  image,  they  mixed  with  the  colours  at  A  in  the  image^- 
and  formed  in  their  motion  a  variety  of  new  and  beautiful  compound  colours  ;  among  thefe  I 
particularly  remarked  a  brown  chocolate  colour,  and  various  other  (hades  and  tinges  of  brown 
arid  purple,  Juft  before  the  fringes  at  B  appeared,  the  fpace  between  A  and  C  was  filled 
with  colours  by  reflexion,  totally  different  in  appearance  from  the  fringes ;  but  I  could  not 
examine  them  f&minutely  as  I  wilhed  in  this  broad  image.  I  therefore  made  the  following 
experiment : 

Obfervation  11.  At  the  hole  in  the  window-fliut  I  held  the  fpeculum,  and,  moved  rt.toi 
fuch  an  inclination  that  tke  colours  by  reflexion  might  be  formed  in  the  image:  they  were 
much  brighter  and  far  more  diftended  than  the  fringes,  and  were  in  every  rcfpei^  like 
the  images  by  reflexion  in  the  common  way,  only  that  the  colours  were  a  little  better  and 
more  regular.     They  were  alfo  feen  on  the  fpeculum,  as  the  third  fat  of  fringes  had  before 

C  c  2  been 


1^6     •  On  the  Properties  of  Light. — Colours  from  Sftcuttr. 

been  in  Obf.  lO;  but  by  letting  the  rays  fall  on  the  half  next  the  chart,  and  inclining  that^all 
very  much,  I  could  produce  them,  though  lefs  diftin^l^Iy,  by  a  fingle  reflexion,  I  now  held  a 
plain  metal  fpeculum,  fo  that  the  rays  might  be  refle£led  to  form  a  white  image  on  a  chart. 
On  inclining  the  fpeculum  much,  1  faw  the  image  turn  red  atthe  edge  ;  it  then  became  a 
little  diftended  ;  and  laftly,  fringes  emerged  from  it  well  coloured,  and  ta  regular  order,  wi;h 
their  dark  intervals.  This  may  eafily  be  tried  by  candle-light  with  a  piece  of  looking-glafs  ; 
and  thofc  who  without  much  trouble  would  fatisfy  themfelves  of  the  truth  of  the  whole  experi- 
nient  contained  in  this  and  the  lafl  obfervation,  may  eafily  do  it  in  this  way  with  a  concave 
fpeculum ;  but  the  beauty  of  the  appearance  is  hereby  quite  impaired.  After  this  detail  it  is 
almofl:  fiiperfluous  to  add,  that  the  fringes  at  B,  fig.  6,  are  formed  by  deflexian  from  the 
edge  of  the  fpeculum  next  the  fun,  and  then  falling  oa  it  are  rcfle(5led  to  the  chart ;  that  the- 
images  by  reflexion  are  either  formed  by  the  light  being  decompounded  at  its  firil  reflexion, 
and  then  undergoing  a  fecond,  or,  in  other  inftances,  without  this  fecond  reflexion;  and  that 
the  other  fringes  are  produced  exactly  as  defcribed  above,  from  the  neceflary  confetiuences 
cf  the  theory.  I  fliall  only  add,  that  nothing  could  have  been  more  pleafing  to  me  than  the 
fuccefs  of  this  experiment;  not  only  becaufe  in  itfeif  it  was  really  beautiful  from  its  variety,. 
but  alfo  becaufe  it  was  the  moft  peremptory  confirmation  of  what  followed  from  the  theory 
a  priori,  and  in  that  point  where  the  fingularity  of  its  confequences  molt  inclined  me  to 
doubt  its  truth. 

Let  us  now  attend  to  feveral  eonclufions  to  which  the  foregoing  obfervations  lead,  inde- 
pendently of  the  propofitions  {viz.  the  five  firft)  which  they  were  made  to  examine. 

I.  We  muft  be  inmediately  flruck  with  the  extreme  refemblance  between  the  rino-s  fur- 
rounding  the  black  fpots  on  the  image  made  by  an  ill-poli(hed  fpeculum,  and  thofe  produced 
by  thin  plates  obfervcd  by  Newton  ;  but  perhaps  the  refemblance  is  (till  more  confpicuous  in 
tile  colours  furrounding  the  image  made  by  any  fpeculum  whatever,  and  fully  defcribed  in 
Obf.  10  and  ii.  The  only  difl^srence  in  the  circumftances  is  now  to  be  reconciled.  The 
Zings  furrounding  the  black  fpot  on  the  top  .of  a  bubble  of  water,  and  thofe  alfo  furrounding 
the  fpot  between  two  objcfl-glafles*,  have  dark  intervals  (exadlly  like  thofe  rings  I  have 
juft  now  defcribed,  and  the  fringes  furrounding  the  fhadows  of  bodies)  j  but  thefe  intervals 
Iranfmit  other  fringes  of  the  fame  nature,  though  with  colours  in  the  reverfe  order;  from 
which  Sir  Ifaac  Newton  juflly  inferred,  that  at  one  thicknefs  of  a  plate  the  rays  were  tranf- 
mltted  in  rings,  and  at  another  refle£led  in  like  rings.  Now  it  is  evident,  that  neither  re- 
fiexibility  nor  refrangibility  will  account  for  either  fort  of  rings  ;  becaufe  the  plate  is  far  too 
thin  for  feparating  the  rays  by  the  latter,  and  becaufe  the  colours  are  in  the  wrong  order  for. 
the  former ;  and  alfo  becaufe  the  whole  appearance  is  totally  unlike  any  that  refrangibility 
and  reflexibility  ever  produce.  To  fay  that  they  are  formed  by  the  thicknefs  of  the  plates,  is 
rot  explaining  the  thing  at  all.  It  is  demanded,  in  what  way?  And  indeed  we  fee  the  like 
dark  intervals  and  the  fame  fringes  formed  at  a  diflance  from  bodies  by  flexion,  where  there 
is  no  plate  through  which  the  rays  pafs.    The  ftate  of  the  cafe  then  feems  to  be  this :  "  When 

*  a  phenomenon  is  produced  in  a  particular  combination  of  circuii.ilaaces,  and   the  fame 

*  phenomenon  is  alfo  produced  in  another  combination,  where  fome  of  the  circumftances 
"  before  prcfent  arc  wanting ;  we  are  entitled  to  conclude,  that  tiic  latter  is  the  mofl  gene- 

*  Optics,  bopk  ii.  p.  i. 

«ral 


On  the  Properties  of  Light.— Colours  from  Specula.  19.7 

♦'rat  cafcy  and  muft  try  to  refolve  the  other  into  it."  In  the  firft  place,  the  order  of  the 
colours  in  the  Newtonian  rings  is  juft  fuch  as  flexion  would  produce-,  that  is,  thofe  which 
are  tranfmitted  have  the  red  innermoft,  thofe  which  are  reflefted  have  the  red  outermolt : 
the  former  are  the  colours  arranged  as  they  would  be  by  inflexion,  the  latter  as  they  would 
be  by  deflexion  ;  and  here  by  outermofl  and  innermoft  muft  be  underftood  relative  pofuiofi' 
only,  or  pofitlon  with  refpe£t  to  the  thicknefs  of  the  plate,  not  of  the  central  fpot.  Second- 
ly, the  thinneft  plate  makes  the  broadeft  ring,  (the  diameter  of  the  rings  being  in  the  inverfe 
fubduplicate  ratio  of  the  plate's  thicknefs)  :  juft  fo  is  it  with  fringes  by  flexion  ;  nearer  the- 
body  of  the  fringes  are  broadeft,  and  their  diameters  increafe  in  the  fame  ratio  with  the. 
diameters  of  the  ringsby  plates  whofe  thicknefs  is  uniform  ;  each  diftance  from  the  bending 
body  therefore  correfponds  with  a  ring  or  fringe  of  a  particular  breadth,  and  the  alternate. 
diftances  correfpond  with  the  dark  intervals.  The  queftion  then  is,  what  becomes  of  the 
light  which  falls  on  or  paffes  at  thefe  alternate  diftances  ?  In  the  cafe  of  thin  plates,  this  light 
is  tranfmitted  in  other  rings :  we  fliould  therefore  be  led  to  think,  that  in  the  cafe  of  the 
light  palling  by  bodies,  it  fhould  be  at  one  diftance  infleiSled,  and  at  another  defledled  :  and. 
in  fa6l  the  phenomena  agree  with  this  ;  for  fringes  are  formed  by  inflexion  within  the, 
fliadows  of  bodies  ;  they  are  feparated  by  dark  intervals  ;  the  fringes  and  the  intervals  with- 
out the  Ihadow  decreafe  in  breadth  according  to  the  fame  law,  fo  that  the  fringes  and  inter- 
vals within  the  (hadow  correfpond  with  the  intervals  and  fringes  without  refpedively.  Nor ' 
Hwill  this  explanation  at  all  affecl  the  theory  formerly  laid  down ;  it  will  only  (if  found  con— 
fjftent  with  farther  indudlion).  change  the  definite  fpheres  of  inflexion  and  deflexion  into- 
alternate  fpheres.  At.  any  rate,  the  fa£ls  here  being  the  fame  with  thofe  defcribed  by 
Newton,  but  in  different  circumftances,  teach  us  to  reconcile  the  difference,  which  we  have 
attempted  todo,  as  far  as  is  confiftent  with  firidnefs;  and  what  we  have  feen  not  only  en- 
titles us  to  concludq  that  the  caufe  is  the  fame,  but  alfo  inclines  us  to  look  for  farther  light' 
concerning  that  caufe's  general  operation:  and  I  truft  fome  experiments  which  T. have, 
l)lanned,  with  an  inftrument  contrived  for  the  purpofe  of  inveftigating  the  ratio  of  the  bendin* 
power  to  the  diftances  at  which  it  a£ls,  will  finally  fettle  this  point. 

XL  Another  conclufion  follows  from  the  experiments  now  related,  viz.  that  we  fee  the  ■ 
great  importance  of  having  fpecula  for  refle£tors  delicately  polifhed,  not:  only  becaufe  the 
more  dark  imperfeftions  there  are  on  the  furface  the  more  light  is  loft,  and  the  more  colours 
are  produced  by  flexion  (thefe  colours  would  be  moftly  mixed,  and  form  white  in  the  focus), 
but  alfo  becaufe  the  fmaileft  fcratches  or  hairs  being  poliftied  produce  colours  by  reflexion^, 
and  thefe  diverging  irregularly  from  the  point  of  incidence  are  never  colledted  into  a  focus,,, 
but  tend  to  confufe  the  image.     Indeed  it  is  wonderful  that  reflcftors  do  not  fuffer  more  from  . 
this  caufe,  confidering  the  almoft  impoflrbility  of  avoiding  the  hairs  we  fpeak  of:  however, . 
that,  they  do  actually  fufl^er  is  proved  by  experience.     I  have  tried  feveral  fpecula  from  re- 
flefting  telefcopes,  and  found  that  though  they  performed  very  well  from  having  a  good 
figure,  yet  from  the  focus  (when  they  were  held  in  the  fun's  light)  feveral  ftreaks  diverged, 
and  were  never  correfted ;  others  had  the  hairs  fo  fmall  that  it  was  very  difficult  to  per- 
ceive the  colours  produced  by  them  unlefs  they  fell  on  the  eye.     Glafs  concaves  were  freer,- 
from  thefe  hairs,  but  they  were  much  more  hurt  by  dark  fpots,  &c.     In  general  the  hairs  . 
are  fo  fmall  in  well  wrought  metals  that  they  do  little  hurt ;  but  v/hen  enlarged  by  any ' 
length,  of .  expofure  to  the  light  and,  heat  in  foIar.obfervtttions>  they  produce  irregularities, 

round: 


1^8  On  the  Proptrtles  of  Light.— IcehrJ  Ci^Jlal 

round  the  image.  Such  at  leaft  I  take  to  be  the  explanation  of  the  phenomenon  obferyei 
at  Paris  by  M.  de  Barros  during  the  tranfit  of  mercury  in  I743>  and  recorded  in  Phil. 
"Iranf.  for  1753.  But  there  is  another  more  ferious  impediment  to  the  performance  of  re- 
^leiSlors,  and  which  it  is  to  be  feared  we  have  no  means  of  removing.  In  making  the  experi- 
ments of  which  the  hiftory  has  been  given,  on  viewing  attentively  the  furface  of  the  fpecu- 
lum,  every  part  of  it  was  feen  covered  with  points  of  colours,  formed  by  reflexion  from  the 
fmall  fpecular  particles  of  the  body.  I  never  law  a  fpcculum  free  in  the  lead:  from  thefe  5  fo 
that  the  image  formed  in  the  focus  mull:  be  rendered  much  more  dim  and  confufed  by  thein 
than  it  otherwife  would  be. 

Ill,  The  laft  conclufion  which  may  be  drawn  from  thefe  experiments  is  a  very  clear  de- 
•monftration  in  confirmation  of  what  was  otherwife  fhewn,  concerning  the  difference  be- 
tween coloured  images  produced  by  reflexion  and  thofe  made  by  flexion.  This  complete 
diverfity  is  moft  evident  in  the  experiments  with  fpecula,  the  colours  produced  by  which, 
■in  the  form  of  fringes  and  rings,  ought,  as  well  as  the  others  defcribed  as  images  by  reflexion 
in  Obf.  1 1,  to  be  the  fame  in  appearance  with  thofe  formed  by  pins  ;  whereas  no  two  things 
can  be  more  diflimilar. 

It  remains  to  examine  the  6th  propofition.  For  this  purpofe  I  made  the  following 
obfervations : 

Obfervation  i.  Having  procured  a  good  fpecimen  of  Iceland  cryftal,  I  fplit  It  into  feveral 
pieces,  and  chofe  one  whofe  furface  was  beft  polifhed.  I  expofed  this  to  a  fmall  cone  of  the 
■fun's  light,  and  received  the  refleded  rays  on  a  chart;  nothing  was  obfervable  in  the  image 
farther  than  what  happens  in  reflexion  from  any  other  poliftied  body.  Some  pieces  indeed 
doubled  and  tripled  the  image,  but  only  fuch  as  were  rough  on  the  furface,  and  confequently 
prefented  feveral  furfaces  to  the  rays.  When  fmooth  and  well  poliflied,  a  fingle  image  was 
all  that  they  formed.  The  fame  happened  if  I  viewed  a  candle,  the  letters  of  a  book,  &c.  by 
reflexion  from  the  Iceland  cryftal. 

Obfervation  2.  I  ground  a  fmall  piece  of  Iceland  cryftal  round  at  the  edge,  and  gave  it  a 
tolerable  polifli  here  and  there  by  rubbing  it  on  looking-glafs,  and  fometimes  by  a  burniftier 
(it  would  have  been  next  to  impofiible  to  polifti  it  completely).  I  then  placed  the  poliflied 
part  in  the  rays  near  the  hole  in  the  window-fhut,  and  faw  the  chart  illuminated  with  a  great 
variety  of  colours  by  reflexion,  irregularly  fcattered  as  defcribed  above*.  I  therefore  held 
the  edge  in  the  fmoke  of  a  candle  and  blackened  it  all  over,  then  rubbed  off  a  very  little  of 
the  foot,  and  expofed  it  again  in  the  rays.  I  now  got  a  pretty  good  ftrcak  of  images  by  re- 
flexion, in  no  refpeft  differing  from  thofe  made  in  the  common  way.  Nor  could  I  ever 
produce  a  double  fet  or  a  fingle  fet  of  double  images  by  any  fpecimen  properly  prepared, 
«ither  on  a  chart  by  the  rays  of  the  fun,  or  on  my  eye  by  thofe  of  a  candle. 

Obfervation  3.  I  ground  to  an  even  and  pretty  Iharp  edge  two  pieces  of  Iceland  cryftal,j 
and  placed  one  in  the  fun's  rays.  At  fome  feet  diftance  I  viewed  the  fringes  with  which  its 
fliadow  was  furrounded,  and  faw  the  ufual  number  in  the  ufual  order.  I  then  applied  the 
other  edge  fo  near  that  their  fpheres  of  flexion  might  interfere  in  the  manner  before  de- 
fcribedf,  and  thus  the  fringes  might  be  diftended  :  ftill  no  uncommon  appearance  took 
place,  nor  when  other  bodies  were  ufed  with  one  edge  of  cryftal,  nor  when  poliflied  pieces 

•  Phil.  Tranf.  for  1796,  p.  470,  or  Phil.  Journal  I.  ,594.        f  Ibid.  p.  256,  or  Phil.  Journal  I.  5J7. 

of 


PheHimitia  of  the  Images  through  Iceland  CryJtaK  T99 

ef  different  (hapes  and  fizes  were  employed.  The  faoic  things  happened  by  candle-light, 
and  alfo  by  refraiSted  homogeneal  light.  In  fliort,  I  repeated  moft  of  my  experiments  oa 
flexion  with  Iceland  cryllal,  and  found  that  they  were  nt>t  changed  at  all  in  their  relults. 

Obfervaiioh  4.     Having  great  reafon  to  doubt  the  accuracy  of  an  experiment  tried  by  Mf, 
Martin,  and  in  which,  by  a  prifm  of  Iceland  cryilal,  he  thought  fix  fpedlra  were  produced,  I 
was  not  much  furprifed  to  find  that  a  prifm  made  by  polifliing  the  two  contiguous  fides  of  a 
parallelopiped  of  Iceland  cryftal  produced  only  two  equal  and  parallel  images,  in  whatever 
pofuion  the  prifm  was  held.    But  though,  from  the  imperfedl  account  which  Martin  gives  of 
this  appearance,  it  was  impofllble  to  difcover  his  error  from  his  own  words,  yet  chance  led 
tne  to  find  out  what  moft  probably  bad  mifled  him  ;  for,  looking  at  a  candle  through  the  op- 
pofite  fides  of  a  fpecimen  of  Iceland  cryftal,  I  faw  four  coloured  images  (befides  two  white 
ones)  of  the  candle.     Thefe  were  parallel  to  one  another,  and  in  the  fame  line  as  reprefented  in 
iig.  7,  plate  VII.  where  E  reprefents  the  two  regular  images,  G  and  F  two  others  coloured' 
very  irregularly,  and  changing  colours  as  the  cryftal  was  moved  horizomally,  fometimes  ap- 
peared each  two  fold,  and  its  two  parts  of  the  fame  or  different  colours.   A  and  B  were  regular-^- 
ly  coloured,  and  evidently  formed  by  refradlion,  and  refieded  back  from  the  fides.     On  turn- 
ing the  cryftal  round  fo  that  its  pofition  might  be  at  right  angles  to  its  former  pofition, . 
the  images  moved  round,  and  were  in  a  line  perpendicular  to  A  B,  as  C  D.     All  this  hap- 
pened in  like  manner  in  the  fun's  rays  ;   and  On  viewing  the  fpecimen  I  found  it  was  fplit 
and  broken  in  the  infide,  fo  as  to  be  lamellated  in  direclions  parallel  or  nearly  fo  to  the  fides  : : 
©n  thefe  plates  there  were  colours  in  the  day-time  by  the  light  of  the  clouds  j  and  it  is- 
cvident  that  it  was  thefe  fradtures  which  caufed  the  irregular  images  G  and  F,  for  other 
fpecimens  {hewed  no  fuch  appearance.     1   would  therefore  conclude,  that  Iceland  cryftal 
feparates  the  rays  of  light  into  two  equal  and  fimilar  beams  by  refraiflion,  and  no  more*. 

As  to  the  caufe  of  the  reparation,  1  would  hope  that  fome  information  may  be  obtained 
from  the  experiments  I  have  related  :  for  from  them  it  appears,  that  this  fingular  property 
extends  no  farther  than  to  the  adtion  of  the  particles  of  Iceland  cryftal  on  the  particles  of 
light  in  their  paffage  through  the  body ;  and  from  Obf.  4,  it  is  farther  evident,  that  it  is  not 
owing  to  the  different  properties  which  Sir  Ifaac  Newton  conjedures  the  different  fides  of 
rays  to  have;  for,  if  this  were  the  caufe,  when  the  rays  pafs  between  two  pieces  of  cryftal 
an  uncommon  flexion  would  take  place.  Laftly,  another  fa£t  (mif-ftated  by  Bartolinf  and 
Rome  de  Lifle:];)  fhews  that  the  unufual  refra£5:ion  takes  place  within  the  body,  while  thc. 
«ther,  like  all  refraftions,  begins  at  fome  finall  diftance  before  the  rays  enter. . 

The  writers  juft  now  quoted  affert,  that  if  the  cryftal  be  turned  round  fo  as  to  aiTumc 
different  pofitions,  there  is  one  in  which  the  line  appears  fingle.     The  fa£t  is  very  different, , 

*  Mentioning  this  account  of  Martin's  miftake  to  Profeflbr  Robifon  of  this  univerfity,  I  was  pleafed  to  find 
a  full  confirmation  of  it.  It  was  that  excellent  philofopher  who  fliewed  tlie  appearance  to  Martin  ;  but  he  no: 
vnderftanding  it,  took  the  liberty  of  publilhing  the  obfervation  as  his  own,  after  firft  mangling  it  in  fuch  a  way- 
it  to  give  him  indeed  fome  pretext  for  the  appropriation.  The  Profeflbr  merely  mentioned  his  having  com- 
municated k  to  Mr.  Martin:  ho\v  the  latter  ufed  it  we  have  fhewn  in  the  text-  the  theory  of  the  appearance  is 
fomewhat  more  complex  than  appears  by  my  obfervations.  I  was  therefore  pleafed  to  find  that  the  Profeffiir  was 
in  poflcffion  of  the  true  account  of  it,  which  is  however  foreign  t9  the  ptefcnt  purp ofe.     B^ 

j-  Experimenta  Cryftalli  abridged  in  Phil.  Tranf.  V0I..V1 

J  CriiiallcgraphJe,  voLi.. 


a»6  Onihe  unufualHourfe  ef  Light  through  Iceland Cryftal. 

as  follows  :  When  the  cryftal  is  turned  round,  the  unufual  image  turjis  round  alfo,  and  ap- 
pears  above  the  other  :  the  grcateft  diftance  between  the  two  images  is  when  they  are 
parallel  to  the  line  bifefling  one  of  the  acute  angles  of  the  parallelogram  through  which  the 
rays  pafs  :  when  the  images  are  parallel  to  a  line  bifedling  one  of  the  obtufe  angles  they 
feem  to  coincide;  but  they  will  be  found,  if  obferved  more  nearly,  to  coincide  only  in  part. 
"Thus  (in  fig.  9,  plate  Vll.)  A  B  and  CD  are  the  two  black  lines  at  their  greater  diftance,  and 
their  extremities  A  and  C,  B  andD,  are  even  with  one  another;  that  is,  the  figure  formed  by 
■joining  A  and  C,  B  and  D,  is  a  reSangle.  But  in  the  other  cafe  (fig.  8),  A  B  and  C  D  being 
the  lines,  the  fpace  CB  (equal  in  deptli  of  colour  to  the  real  line  on  the  paper)  is  the  only 
j)lace  in  which  the  lines  (or  images)  coincide.  The  fpace  A  C  of  A  B,  and  B  D  of  CD 
are  ftill  of  alight  colour,  and  the  two  lines  AB  and  CD  do  not  coincide,  by  the  difference 
A  C  or  B  D  i  that  is,  by  the  difi^srence  O  P,  the  greateft  diftance  (fig.  9).  In  (hort,  the  un- 
■ufualline's  extremities  defcribe  circles  (in  the  motion  of  the  cryftal)  whofe  centres  are  the 
extremities  of  the  ufual  line,  and  whofe  radii  are  the  greateft  diftance.  From  this  it  appears 
■evident,  that  the  unufual  image  is  formed  within  the  cryftal,  and  turns  round  with  the  fide 
•of  the  particle  or  rhomboidal  mafs  of  particles  which  forms  it.  Farther,  it  is  evident  that 
-the  power  which  produces  the  divifion  of  the  incident  light  is  very  different  from  common 
refraftion,  from  the  motion,  and  the  £ffe£t  taking  place  when  the  rays  are  perpendicular. 
Sufpeding,  therefore,  that  it  might  be  owing  to  flexion,  I  made  the  following  experiment, 
which  undeceived  me  : 

Obfervation  5.  I  covered  one  fide  of  a  fpecimen  of  Iceland  cryftal  three  inches  deep  witlt 
■tlack  paper,  all  but  a  fmall  fpace  3-0  of  an  inch  in  diameter,  and  placed  a  fcreen  with  a 
hole  of  the  fame  fize,  fix  feet  from  the  hole  in  the  vvindow-ftiut  of  my  darkened  chamber,  fo 
that  the  rays  might  pafs  through  the  fcreen  and  fall  on  a  prifni  placed  behind,  to  refracSt 
them  into  a  fmall  and  well  defined  fpe£trum,  which  was  received  on  a  chart  two  feet  from 
the  prifm.  This  fpedrum  I  viewed  through  the  cryftal,  and  of  courfe  faw  it  doubled  ;  but 
the  two  images  were  by  no  means  parallel :  the  unufual  one  inclined  to  the  red,  and  its  violet 
was  confiderably  farther  removed  from  the  violet  of  the  other,  than  the  two  reds  were  from 
one  another ;  which  fhews  that  the  moft  refrangible  or  leaft  flexible  rays  were  fartheft  moved 
from  their  courfe  by  the  unufual  action,  and  proves  this  to  be  very  diiFerent  from 
flexion*. 

From  all  thefe  obfervations  this  conclufion  follows :  that  the  remarkable  phenomenon  in 
queftion  arifes  from  an  adlion  very  different  from  either  refraftion  or  flexion,  and  whofe  na- 
ture well  deferves  to  be  farther  confidered.  It  may  poffibly  belong  to  the  particles  of  Iceland 
cryftal,  and  in  a  degree  to  thofe  of  rock  cryftal,  from  the  form  and  angles  of  the  rhomboidal 
maffes  whereof  thefe  bodies  are  compofed.  Nor  is  this  conjefture  at  all  difproved  by  the  fail, 
that  glafs  fliaped  like  thefe  bodies  wants  the  property  ;  for  we  cannot  mould  the  particles  of 
glafs,  we  can  only  fliape  large  malTes  of  thefe  ;  whereas  we  cannot  doubt  that  in  cryftallization 
the  fmalleft  mafTes  afTume  the  fame  form  with  the  largeft.  But  then  other  hypothefes  may 
perhaps  alfo  account  for  the  fail,  fuch  as  atmofpheres,  eletSlric  fluid,  &c.  &c. ;  fo  that  till 
farther  obfervations  are  made  we  ought  to  reft  contented  with  barely  fuggefting  the  query. 
,Xn  the  mean  time,  referving  to  a  future  opportunity  fomc  inquiries  concerning  the  chemical 

•  When  a  candle  cr  line  is  viewed  tlirough  a  deep  fpecimen,  the  unufual  image  it  tinged  with  cotours. 

propertJM 


*  »,  Propojiikns  re/^eBlng  Lighl. — Bttuminsi  jOt 

properties  of  light,  and  the  nature  of  the  forces  which  bodies  exert  on  it  internally,  I  con- 
clude at  prefent  with  a  fliort  fummary  of  propofitions.  But,  firft,  may  I  be  permitted  to  ex- 
prefs  a  hope,  that  what  has  been  already  attempted  (and  for  which  no  praife  can  be  claimed 
farther  than  what  is  due  to  attentive  obfervation,  according  to  the  rules  of  the  immortal 
Bacon)  may  prove  acceptable  to  fuch  as  love  to  admire  the  beautiful  regularity  of  nature, 
or  more  particularly  to  trace  her  operations,  as  exhibited  in  one  of  the  mofl  pleafing,  moft 
important,  and  moft  unerring  walks  of  phyfical  fcience. 

Propofttion  I.  The  fun's  light  confifts  of  parts  which  differ  in  degree  of  refrangity,  re- 
flexity,  inflexity,  and  deflexity ;  and  the  rays  which  are  moft  flexible  have  alfo  the  greateft 
refrangity,  reflexity,  and  flexity — or  are  moft  refrangile,  reflexile,  and  flexile. 

Propofttion  II.  Rays  of  compound  light  pafling  through  the  fpheres  of  flexion,  and  falling 
on  the  bending  body,  are  not  feparatcd  by  their  flexibility,  either  in  their  approach  to,  or  re- 
turn from,  the  body. 

Propofttion  III.  The  colours  of  thin  and  thofe  of  thick  plates  are  precifely  of  the  fame 
nature,  differing  only  in  the  thick;nefs  of  the  plate  which  forms  them. 

Propefition  IV.  The  colours  of  plates  are  caufed  by  flexion,  and  may  be  produced  with- 
out any  tranfmiflion  whatever. 

Propofttion  V.  All  the  Confequences  deducible  from  the  theory  a  priori  are  found  to  fol- 
low in  faft. 

Propofttion  VI.  The  common  fringes  by  flexion  (called  hitherto  the  "  three  fringes") 
are  found  to  be  as  numerous  as  the  others. 

Propofttion  VII.  The  unufual  image  by  Iceland  cryftal  is  caufed  by  fome  power  inherent 
in  its  particles,  difl^erent  from  refradtion,  reflexion,  and  flexion. 

,  Propofttion  VIII.  '  This  power  refembles  refradtion  in  its  degree  of  action  on  different 
rays;  but  it  refembles  flexion  within  the  body,  in  not  taking  place  at  a  diftance  from  it,  in 
a£ting  as  well  on  perpendicular  as  on  oblique  rays,  and  in  its  fphere  or  Ipace  of  exertion 
moving  with  the  particles  which  it  attends. 


11. 

Ohfervations  on  Bituminous   Suhftances,  with  a  Defcriptlon  of  the  Varieties  of  the  Elaflic 
Bitumen.    By  CHARLES  HATCHETTy  Efq.  F.R.S.  Land,  and  Edin.  F.L.S.  i^c* 


I 


SECT.  I. 

T  is  now  generally  believed  that  the  bituminous  fubftances  are  not  of  mineral  origin, 
but  that  they  have  been  formed  from  certain  principles  of  fubftances  belonging  to  the 
organized  kingdoms  of  Nature,  which,  after  the  lofs  of  animal  and  vegetable  life,  have  fuffer- 
ed  confiderable  changes  by  long  contaft  and  union  with  mineral  bodies. 

Thefe  changes  have  been  however  fo  confiderable,  that  the  bitumens  can  no  longer  be  re- 
ferred to  their  firft  origin,  and  they  are  therefore  regarded  by  general  confcnt  as  forming 
part  of  the  prefent  mineral  fyftem. 

•  Read  before  the  Linmean  Society  in  June  and  July  179T. 

Vol,  11 — August  1798.  '  Dd  The 


102  D'tvijion  of  Bitumlnou}  Subfianctfi 

The  bituminous  fubftances  are  :  ~ 

Naptha,  Jet, 

Petroleum,  Pit  Coal, 

Mineral  Tar,  Bituminous  Wood, 

Mineral  Pitch,  .     Turf, 

jAfphaltum,  Peat,  and 

thofe  combinations  of  the  oxides  of  certain  metals  with  bitumen  called  Bituminous  Ores*. 

Thofe  who  are  acquainted  with  the  nature  of  thefe  fubftances  will  immediately  perceive, 
that  they  may  be  formed  into  two  divifions  :  the  firft  of  which  confifts  of  fimple  fpecies,  or- 
unadulterated  bitumens :  and  the  fecond  is  compofed  of  bitumen  mixed  or  combined  with 
the  earths,  vegetable  matter,  and  metallic  oxides  ;  fo  that  thefe  appear  to  merit  the  name  of 
compound  fpecies. 

I  {hall  now  firft  confider  how  the  fimple  fpecies  are  connedted  with  each  other. 

SECT.  II. 

IT  has  been  the  opinion  of  fome  eminent  Naturalifts  and  Chemifts,  that  naptha  is  an 
ethereal  oil  produced  from  the  more  compa£t  and  folid  bitumens  by  a  fort  of  natural  diftilla- 
tion.  This  however  appears  to  be  an  hypothefis  founded  upon  analogy,  and  fupported  only 
by  a  few  local  fadls,  which  may  often  be  queftioned.  But  many  fa6ls  and  obfervations  con-.- 
Cur  to  prove  that  the  contrary  moft  frequently  happens,  and  that  the  compaft  bitumens  arc 
often,  if  not  always,  formed  from  naptha  and  petroleum  by  infpilTation.  I  will  not  however, 
now  infift  upon  theproofe  of  this,  as  the  varieties  of  the  elaftic  bitumen,  which  I. {hall  foon 
defcribe,  will  be  fuiEcient  for  the  purpofe  t« 

NAPTHA. 

Naptha  is  a  fubftance  well  known  to  Mineralogifts,  as  a  light,  thin,  often  colourlefs  oif, 
highly  odoriferous  and  inflammable,  which  is  fometimes  found  on  the  furface  of  the  waters 
©f  fprings,  and  at  other  times  ilfuing  from  certain  ftrata. 

When  expofed  to  the  air,  it  becomes  at  firft  yellow,  afterwards  brown,  and  in  the  like 
proportion  it  thickens,  and  pafles  into 

PETROL  OR  PETROLEUM. 

This  has  a  greafy  feel,  is  thicker  than  the  preceding  fubftance,  is  tranfparent  or  femi- 
tranfparent,  and  of  a  reddifh  or  blackilh  brown  colour.  By  air  it  becomes  like  tar,  and 
then  is  called 

•  As  I  intend  only  here  to  notice  the  modifications  of  naptha  and  petroleum,  I  have  not  mentioned  ambei" 
and  the  honey-ftone. 

•f-  Bergman  was  of  opinion,  that  the  liquid  bitumens  were  ofteir,  if  notalways,  formed  from  thofe  which  are 
folid,  by  the  means  of  fubterraneous  lieat;  and  exprclTcs  himfelf  thus:  "  Caeterum  ad  fidem  pronum  eft, 
naptham,  petroleum,  bituminofofque  liquores,  quibus  abundat  Afia,  plures  harum  materierum  exhibens  noa 
tantum  fcaturigines,  fed  rivulos  quoque,  quibus  etiam,  parcius  licet  diftributis,  Auflralis  Europa  non  caret : 
probabiie,  inquam,  eft,  has  pinguedines  liquidas  variis  antea  terris  inhsefifle  exficcatas,  et  mediante  calore 
fubterraneo,  fi  non  fempcr,  fajpe  tamcn  fluiditatem  recuperSfle.  Novimus  ignem  in  alto  baud  raro  agere, 
quamvis  in  fuperficie  vix  obfcura  ejufdem  indicia  iiiveftigare  liceat:  novimus  practerea  e  ficco  aluminari  fchifto 
petroleum  cxtorqueri  jufto  calorii  gradu,  cui  arte  exponitur.— Bergman  de  Produftis  Vuicaniis  Opufcula, 
torn.  Ui.  p.  ajS. 

MOUN- 


Dlvt/tm  of  Bituminous  Suhjlaneis.  20  J 

MOUNTAIN  OR  MINERAL  TAR,  Bitumen  PETaotEUM  tarde  fluens. 
This  fubftance  is  vifcid,  and  of  a  reddifh  or  blackifli  brawn  or  black.     When  burned,  it 
emits  a  difagreeable  bituminous  fmeli,  and  by  expofure  to  the  air  itpaflss  into 

MOUNTAIN  OR  MINERAL  PITCEI— Bitumen  TvIaltha. 

The  mineral  pitch  much  refembles  common  pitch,  and,  when  heated,  emits  a  ftrono-  un- 

pleafant  odour,  like  the  former  fubftance.     When  the  weather  is  cold,  it  may  be  broken, 

and  then  exhibits,    internally,   a  glaffy  luftre;  but  when  warm,  it  is  foftened,  and  poffcfTes 

feme  tenacity.     It  is  however  fufccptible  of  a  fuperior  degree  of  induration,  and  then  becomes 

ASPHALTUM — Bitumen  Asphaltum — Petroleum  induratum. 

This  is  a  light,  brittle  fubftance,  of  a  brownifli  black,  or  black.  When  broken,  it  ftiews 
a<:onchoidal  fradlure  with  a  glafty  luftre.  It  has  little  of  the  bituminous  odour,  unlefs  it  is 
rubbed  or  heated.  It  eafily  melts,  is  very  inflammable,  and,  when  pure,  burns  without' 
leaving  any  aflies. 

In  this  manner,  naptha,  by  infpifTation,  paff<s  fucceflively  through  different  ftates  until  it 
becomes  afpbaltum,  which  appears  to  be  the  ultimate- degree  of  induration  which  the  pure 
bitumens  derived  from  naptha  can  receive. 

I  have  at  this  time  fpecimens  before  me  which  prove  thefe  gradations ;  and  I  Jiave  ktn  a 
remarkable  inftance  in  a  bitumen  brought  from  the  Ifland  of  Trinidad,  which  exhibits 
mineral  tar  pafling  into  mineral  pitch,  and  laftly  into  afphaltum*. 

SECT.  III. 

THE  divifion  which  comprehends  the  fimple  bituminous  fubftances  derived  from  naptha, 
may  therefore  be  confidered  as  terminating  in  afphaltum ;  but  nature  appears  to  have  glided 
on  by  an  uninterrupted  chain  which  conne£ls  the  ftmple  bitumens  with  thofe  which  we  have 
called  compound  ;  and  this  effe£l  is  produced  by  the  gradual  increafe  of  the  carbonic  princi- 
ple, and  the  introdu£lion  of  extraneous  matter,  the  different  quantity  of  which,  together 
with  the  greater  or  lefs  degree  of  mixture  or  of  chemical  union,  occafion  confiderable  changes 
in  thefe  fubftances,  fo  that  they  are  gradually  rernoved  from  thofe  characters  which 
diftinguifti  the  pure  bitumens. 

To  form  an  accurate  table  of  thefe  gradations,  it  would  be  neceffary  to  have  comparative 
analyfes  of  the  different  bituminous  fubftances,  and  alfo  to  contraft  the  analyfes  with  the 
properties  of  thefe  bodies.  But  at  prefent  thefe  analyfes,  for  the  greater  part,  are  wanting  ; 
and  although  at  fome  future  time  I  intend  to  attempt  a  feries  of  fuch  experiments,  I  muft 
now  content  myfelf  with  the  obfervations  and  fa^ts  which  I  have  been  able  to  colledlf. 

*  The  progreffive  changes  of  naptha  into  petroleum,  miperal  tar,  mineral  pitch,  and  afplialtum,  appear  to  be 
caufed  by  the  gradual  diffipation  of  part  of  the  hydrogen  of  the  bitumen,  and  the  conl'equent  development  or 
difengagement  of  carbon.  Hence,  I  am  inclined  to  believe,  arife  the  changes  of  colour,  the  degrees  ef  in- 
fpiffation,  and  the  increafed  proportion  of  carbon  found  in  thofe  fubftances  by  chemical  analyfis.  I  would  be 
underftood  however  to  mean  that  the  carbon  is  only  relatively  increafed,  in  relpeft  to  the  other  ingredients,  in 
a  given  quantity  of  thefe  bitumens,  and  that  it  predominates  in  proportion  to  the  di/fipation  of  a  certain 
portion  of  the  hydrogen,  which  was  originally  neceffary  to  the  forming  of  the  bitumen  in  conjunction  with  the 
carbon. 

f  This  paper  was  written  and  read  before  I  had  feen  the  ingenious  experiments  which  the  celebrated 
Mr.  Kirwan  has  publifhed,  in  the  laft  edition  of  his  Elements  of  Mineralogy.— Vide  vol.  ii.  p.  514,  (or 
Pbilof.  Joum.  I,  4«7.) 

D  d  a  Ff  on» 


404  Comfound  Bttumem. — Jet. — Cannel  Coal, 

From  thefe  I  am  of  opinion,  that  the  moft  immediate  gradation  from  afphaltum  (which  is 
the  laft  of  the  fimple  bitumens)  into  thofe  which  are  compound,  takes  place  ia  the  fub- 
ftance  called 

JET. 

Jet  is  a  fubftance  well  known  to  be  of  a  full  black,  fometimes  however  inclining  t» 
brown.  It  is  confiderably  harder  and  lefs  brittle  than  afphaltum.  It  breaks  with  a  con- 
choidal  fradure,  and  the  internal  luftre  is  glafTy.  It  has  no  odour  except  when  heated,  and 
it  then  refcmbles  afphaltum.  It  melts  in  a  ftrong  heat,  and,  when  burned,  leaves  an  earthy 
refiduum. 

Wallerius  confidered  jet  as  afphaltum  which  had  become  indurated  by  time,  and  Mr. 
Fourcroy  is  of  the  fame  opinion*.  '  Others  again  have  arranged  it  with  the  varieties  of 
coalf.  I  am  inclined  however  to  believe,  that  it  is  neither  afphaltum  nor  coal,  but  an  in- 
termediate fubftance  which  may  be  regarded  as  the  firft  gradation  from  the  fimple  bitumens 
into  thofe  which  are  compound.  The  matter  of  afphaltum  undoubtedly  enters  into  it  in  a 
large  proportion,  and  has  confequently  damped  feveral  of  its  characters  upon  it ;  but  the  in- 
creafe  of  carbon,  and  of  the  extraneous  or  earthy  matter  which  is  intimately  mixed  or 
rather  combined  with  it,  has  had  fo  much  influence,  that  the  characters  of  coal  are  alfo  in 
fome  meafure  ap,)arent,  and  are  rendered  the  more  ftriking  by  the  fimilarity  of  certain  local 
circumftances  which  attend  thefe  two  fubftances.  The  characters  of  coal  are  however  by 
no  means  fully  eftablifhed  in  jet ;  but  from  this  we  pafs  immediately  to  another,  in  which 
thefe  characters  cannot  be  queftioned. 

This  is  the  fubftance  called 

CANNEL  COAL, 

which  is  of  a  full  black,  of  a  fmooth,  folid,  even  texture;  it  breaks  in  any  direCtion,  and  the 
tranfverfe  fraCture  is  conchoidal.  It  burns  well,  and  is  fo  compaCt  that  it  is  often  employed, 
like  jet,  to  be  formed  into  trinkets. 

The  great  refemblance  which  cannel  coal  has  to  jet  in  many  of  its  properties,  induces  me 
to  regard  it  as  the  next  gradation  of  the  compound  bituminous  fubftances,  and  as  the  lead- 
ing variety  of  coal  from  which  the  others  follow  according  to  the  degree  of  their  bituminous 
character. 

The  limits  of  this  paper  will  not  allow  me  to  enter  into  a  circumftantial  account  of  all  the 
other  varieties  of  pit-coal ;  neither  is  it  neceffary,  after  the  gradations  of  afphaltum  to  jet, 
and  of  jet  to  coal,  have  been  noticed.  I  (hall  not  therefore  defcribe  the  varieties  of  coal 
known  by  divers  names  in  different  countries,  and  even  in  different  provinces,  fuch  as  thofe 
called  in  England  caking  coal,  rock  coal,  fplent  coal,  &c.  &c.  i  but  (hall  only  obferve,  that 
the  pit  coals  in  general  appear  to  be  compofed  of  bitumen  intimately  mixed,  or  rather 
combined,  with  various  proportions  of  carbon  and  earthy  matter ;  and  according  to  the 
intimacy  of  the  union,  and  the  excefs  of  one  or  other  of  the  ingredients,  fo  the  com- 
pound poffeffes  more  or  lefs  the  characters  of  perfeCl  coal,  or,  by  various  (hades,  paflfes 
into  certain  earthy  or  ftony  fubftances,  which,  although  impregnated  with  bitumen,  do 


*  El^mens  d'Hift.  Nat.  ct  de  Chimie,  torn.  iii.  p.  456. 
t  Widenmann's  Handbuch  der  Mineralogie,  p.  628. 


not 


0fi  the  CombufitoH  tf  Coal,  (Sfc.  2©5 

not  merit  the  appellation  of  coal,  and  thefe.  alfo  at  length  gradually  lofe  the  bituminous 
charader  *.  - 

It  is  likewife  worthy  of  notice,  that  the  quantity  of  earthy  matter  does  not  appear  to  be 
the  principal  caufe  why  pit-coals  do  not  burn  with  the  rapidity  which  is  to  be  perceived  in 
feme  other  earthy  fub(taiv:es  impregnated  with  bitumen.  For  we  may  conclude,  that  the 
flow  combuftion  of  coal  proceeds  from  the  joint  efFefls  produced  partly  by  the  relative  pro- 
portions of  the  bituminous,  carbonaceous,  and  earthy  ingredients,  and  partly  by  the  more  or 
lei's  perfeft  degree  of  mixture  which  connedls  them  together,  and  which  degree  of  mixture, 
I  believe,  in  many  cafes,  nearly  approaches  1o  chemical  union,  if  not  adlually  fo  :  when, 
therefore,  the  degree  of  mixture  is  fo  perfect  as  that  every  particle  of  bitumen  is  connedted 
with  much  carbon  or  earthy  matter,  it  is  not  furprifing  that  the  rapid  combuftible  property 
of  the  former  fliould  be  checked  in  a  confiderable  degree ;  and,  by  a  parity  of  reafoning, 
when  the  mixture  is  grofs  and  imperfcft,  fo  that  it  confifts  of  a  ftony  or  earthy  fubftance, 
which  has  fimply  imbibed  bitumen,  it  is  natural  to  expeil  that  the  bitumen  (although  lefs 
abundant  than  in  coal)  fhould  enter  readily  into  combuftion,  which  is  vehement  in  propor- 
tion to  the  fliortnefs  of  its  duration ;  and  this  we  find  to  be  the  cafe  in  many  earthy  fub- 
ftances,  and  loofe  fand-llones  which  are  fimply  impregnated  with  bitumen. — To  return, 
hovvever,  to  the  varieties  of  coal,  I  muft  obferve,  that,  from  the  caufes  above-mentioned, 
the  different  charadters  and  properties  of  coal  appear  to  nie  to  be  produced.  That  in  this 
manner,  perfe(5l  pit-coal  pafles  into  fchiftofe  or  ilaty  coal ;  and  this  again,  by  certain  grada- 
tions, paffes  into  the  varieties  of  combuftible  or  bituminous  fchiftus ;  which  alfo,  by  the 
gradual  decreafe  of  the  bituminous  ingredient,  become  at  length  confounded  with  the 
Tarieties  of  the  common  or  argillaceous  fchiftus. 

We  have  a  remarkable  example  of  this  in  the  gradations  of  bituminous  fchiftus  into 
argillaceous  fchiftus,  which  are  to  be  obferved  at  Kimmeridge,  on  the  coaft  of  Dorfetlhlre, 
where  a  peculiar  bituminous  fchiftus  Is  found,  which  is  ufed  as  fuel  by  the  inhabitantSj  and 
is  improperly  called  Kimmeridge  coal. 

By  the  feries  of  gradations  which  have  been  noticed  In  the  foregoing  pages,  the  fimple 
bituminous  fubftances  appear  to  pafs  into  thofe  which  are  compound ;  and  thefe  alfo,  by  de- 
clining (hades,  at  laft  pafs  into  fubftances  appertaining  to  the  clafs  of  earths  afid  ftones. 
■  In  the  compound  bituminous  fubftances  the  prevalent  earthy  ingredient  Is  for  the  greater 
part  generally,  if  not  always,  argillaceous;  and  although  certain  calcareous  grits  (fuch  as 
the  Portland  ftonef)  as  well  as  limeftones  and  marbles  are  found  impregnated  with  bitumen, 
yet  I  know  not  of  any  inftance  in  which  this  happens  to  the  degree  requifite  to  form  a  com- 
buftible fubftance. 

Thiscurfory  view  of  the  fimple  bitumens,  and  of  their  combinations,  would  be  fufficient 
as  an  introduftion  to  the  principal  fubjeit  of  this  paper  ;  but,  to  complete  the  feries,  1  ftiall 
make  fome  obfervations  on  the  vegetable  fubftances  which  contain  bitumen,  and  ftiall  after- 
wards mention  the  mixtures  of  bitumen  with  metallic  oxides. 

•  From  Mr.  Kirwan's  experiments  it  appears  that  carbon  is  a  conftituenf.  principle  of  coal,  and  tliat  the  pre- 
fence  of  it  is  a  principal  caufe  of  thofe  modifications  which  produce  the  fpecics.  It  even  feems  chiefly  to  forra 
the  Kilkenny  coal. — Kirwan's  Elements  of  Mineralogy,  vol.  ii.  p.  5ZI. 

t  The  Portland  ftone,  when  recently  broken  in  the  quarries,  emits  a  ftrong  bituminous  odour,  like  the  b!tu» 
minnus  limeftone  or  ftink-ftone.    It  is  alfo  full  of  extraneous  foflils,  or  at  leaftthe  veftigcs  of  them. 

SECT.  IV. 


io6  Aluminous  TFood,  Bovey  Csal^  IS-l^ 

SECT.  IV. 
'WHEN  we  confider  the  fads  which  apparently  prove  that  vegetables  have  contributed 
-principally  to  the  formation  of  bitumen,  we  have  every  -reafon  to  expe£t  that  mixtures  of 
vegetable  matter  with  bitumen  fliould  frequently  occur.     But  by  the  mixture  of  bitumea 
with  the  parts  of  vegetables,  we  underftand  the  remains  and  parts  of  vegetables  mixed  and 
>.Conne£tcd  with  tiie  bitumen  which  they  themfelves  have  produced. 
■This  fecms  to  be  the  nature  of  the  fubftance  called 

-BITUMINOUS  WOOD,  as  well  as  of  TURF  and  PEAT. 
"Bituminous  or  foffil  wood  is  found  in  many  places  ;  but  in  refpect  to  that  which  is  found 
atBovey,  near  Exeter,  and  which  is  therefore  called  Bovey  coal,  there  are  forae  peculiarities 
which  deferve  to  he  mentioned.     The  Bovey  coal  is  a  darlc  brown,  light,  brittle  fubftance, 

Avhich  in  texture  and  other  external  properties  much  refembles  wood  which  has  been  half 

•  charred.    3t  is  not  found  as  fcattered  lags  or  trunks,  but  forms  regular  flrata. 

The  pits  are  on  a  heath  which  is  flat  and  fandy  ;  the  ftratum  of  fand  is  however  but  thin, 
after  which  a  pale  brownifli  grey  clay  is  found  mixed  with  quartz  pebbles.  This  prevails  to 
about  fix  feet,  at  which  depth  the  firft  flratum  of  the  coal  commences.  The  quality  of  this 
is  however  much  inferior  to  that  of  the  fubfequent  ftrata,  which  in  all  amount  to  feventeen, 

-producing  a  depth  of  nearly  feventy-four  feet  from  the  furface.  Between  each  ftratum  of 
coal  is  a  ftratum  of  clay.  The  diredion  of  the  ftrata  is  from  eaft  to  weft,  and  the  inclina- 
tion or  dip  is  from  north  to  fouth.  The  inferior  ftrata  arc  thought  to  afford  the  beft  coal, 
and  the  coalis  more  folid  and  of  a  better  quality  towards  the  fouth.    The  thickeft  ftratum 

•of  coal  is  from  fix  to  eight  feet*. 

The  Bovey  coal  burns  readily  with  a  flame  like  half-charred  wood  :  it  does  not  crackle, 

.:and,  if  but  moderately  burned,  forms  charcoal ;  or  if  completely  burned,  it  leaves  a  fmall 
quantity  of  white  afties  exaflly  fimilar  to  thofe  of  wood.  The  fmell  of  it  when  burning  alfo 
refembles  that  of  wood,  with  a  faint  difagreeable  odour.  It  is  certainly  very  remarkable 
that  this  fubftance  (h&uld  form  regular  ftrata,  although  it  poffeiTes  the  texture  and  moft  of  the 
properties  of  wood  ;  and  that  thefe  ftrata  do  not  exhibit  any  of  thofe  irregularities  on  their 
furfaces,  which  might  be  expelled,  on  the  fuppofition  that  they  were  formed  by  the  roots, 
trunks,  and  branches  of  trees  long  buried  in  the  earth.  It  is  alfo  difficult  to  imagine  wood 
to  have  been  tranfported  and  depofited  in  this  place  at  feventeen  different  periods,  and  yet 
it  muft  be  allowed  that  thefe  ftrata  have  been  formed  by  fucceffive  operations.  I  muft  con- 
fefs,  that  after  having  twice  vifited  and  examined  the  fpot  exprefsly  for  the  purpofe,  I  ftill 
find  myfelf  utterly  unable  to  offer  any  opinion  upon  the  fubjeft. 

The  charafters  of  bitumen  are  but  little  apparent  in  the  Bovey  coal,  and  the  fuperior 
(Irata  even  appear  to  have  loft  a  portion  of  their  combuftible  principle,  while  the  inferior 
ftrata  poffefs  it.  The  lower  parts  alfo  of  thefe  ftrata  are  more  compadt  and  more  combuftible 
than  thofe  parts  which  are  immediately  upon  themj-. 

Another 

•  In  the  winter,  twelve  men  can  raife  about  no  tons  of  tills  coal  in  a  week,  the  whole  of  which  is  employed 
in  a  neighbouring  pottery. 

f  At  about  100  yards  to  the  weft  of  the  pits,  is  a  bog  of  confiderablc  extent,  where  peat  is  cut,  and  decayed 
iceets  and  trunks  of  trees  are  found,  which  do  not,  however,  in  the  leaft  approach  to  the  nature  of  the  Bovey 

•coal. 


Situm'inous  Woody  Sur-iurirafid,  bfc.  207 

Another  remarkable  fort  of  foffil  wood,  which  much  refembles  the  Bovey  coal,  and  in  like 
manner  is  arranged  among  the  bituminous  woods,  is  that  found  in  Iceland,  which  is  called 
by  the  inhabitants  Surturbrand.  This  is  rather  harder  than  the  Bovey  coal,  but  in  every 
other  refpeft  is  the  fame.  It  alfo  forms  ftrata  many  feet  in  thicknefs  ;  but  it  is  very  extra- 
ordinary that  thefe  ftrata  appear  to  be  formed  of  trunks  of  trees,  which,  in  their  tranfverfe 
fe£lion,  exhibit  the  concentric  circles  of  their  annualgrowth,  with  this  difference,'  that  the 
trunks  have  been  fo  comprefTed  as  to  be  nearly  flat,  fo  that  the  circles  appear  like  parallel 
lines  conneited  at  their  extremities  by  a  fliort  curve. 

I  did  not  obferve  fuch  an  appearance  at  Bovey ;  but  this  would  depend  upon  the  pofitioh 
of  the  trunks  of  the  trees,  in  refpeft  to  the  fedlion  of  the  ftrata. 

Chaptal*,  Troilf,  Bergman  J,  and  many  others,  have  been  of  opinion  that  the  furturbrand 
is  wood  which  has  been  charred  by  the  heat  of  the  lava.  But  I  cannot  difcem  why  it  Ihould 
be  fuppofed  that  it  has  been  a£led  upon  by  fire,  any  more  than  that  the  Bovey  coal  has  been 
fubjeded  to  the  efFe(fts  of  the  fame  agent.  The  qualities  of  the  two  fubftances  are  the  famej  , 
and  as  (from  Archbifhop  ■  Troll's  and  ProfelTor  Bergman's  account)  the  furturbrand  is 
flratified,  I  think  we  may  venture  to  pronounce  that  the  circumftances  under  which  they 
are  found,  are  alfo  fimilar§.     The  whole,  therefore,  of  the  opinion  in  falvour  of  fire,  appears 

«oal.     Whether  this  hog  has  been  in  any  manner  connefted  with  the  formation  of  the.  above-mentioned  fub- 
ftance,  I  do  not  pretend  to  determine. 

A  yellowifh  brown  compaft  fubftmce,  which  in  colourand  fracture  refembles  ferruginous  clay,  is  alfo  found 
occafionally  with  the  Bovey  coal  :  it' is  brittle,  and  is  highly  inflammable;  it  melts  like  a  bitumen,  and  emits  a 
fmoke  which  in  fmell  refembles  amber.     This  fubftance  is  but  rarely  found.' 

•  Element!  of  Chcmiftry,  vol.  iii.  p.  197. 

f  Von  Troll's  Letters,  p.  43. 

J  Quid  de  ligno  folhli  Iflandix  fentiendum  fit,  gnaro  in  loco  natali  contemphtori  decidendum  relinquimus. 
Interea,  utcum  Vulcani  operationibus  nexum  credamus,  plures  fuadent  rationes,  quamvis  hue  ufque  modum 
ignoremus,  quo  fitum  texturamque  adquifiverunthaec  ftrata.  Scilicet  truncis  arborum  perquam  craffis  coiiftant, 
qualis  in  Iflandia  nul'ibi  repcriuntur,  et  ne  quidem  hoc  tempore  crefcere  poile  videntur.  Hi  fitu  horizontal! 
in  ftratis  multorum  pedum  craffitiei  congefti  funt  ct  petrolco  plus  minus  penetrati,  non  jam  moUi,  fed  optime 
indurato,  a  quo  tam  nigrorem,  quam  flammae  fub  deflagratione  qualitatem  mutuantur.  Sed  quod  in  primis 
attentionem  merctur,  ell  truncorum  in  lamellas  planas  comprcffio. 

Ponamus  truncum  arboris  cujufdam  tranfverfim  feftum,  hinc,  uti  notum  efl:,  figura  oritur  in  orbem  redicns 
circiter  circularis,  qurt  omnia  monftrat  anuotina  incrementa,  extimo  ptopemodum  parallcla. .  Fingamus  jam  .v 
talem  fe&ionem  in  tenuem  laminam  comprtffam,  et  veram  habebvmus  ligni  foflilis,  de  quo  hcic  agitur,  ideam'; 
nam  in  magnis  hujus  materis  fruftis,  tranfvcrfim  feftis,  quemlibet  annotinorum  orbium  vifu  pcrfequj  licet,  ita 
plerumqiie  coaftum,  ut  duas  lineas  fere  parallelas  exhibeat,  quarumextrema  brevi  flexura  funt  adunata. — Qua 
autem  immanis  requiritur  vis,  ut  truncus  cylindricus  ita  complanetur  ?  Nonne  antea  particulai'um  nexus 
putredinis  qucdam  gvadu  fuerit  relaxatus  ?  Certe,  nifi  compages  quodammodo  mutatur,  quodlibet  pondus  in- 
cumbens  huieeffeflui  erit  inipar.     Ca;terum  idemobfervatur  phsenomenon  in  omni  fchiftoargUlaceo>'-. 

Onhoceratitse,  qusin  ftrato  calcareo  conicam  figurara  perfeQe  fervam,  jn  fchifto,planum  fere  triahgulare 
comprefliorie  efliciunt.  Idem  valet  de  pifcibus, ,  conchis,  infeftifque  petrifaftis.  Caufa  adbuc  latet,  fed  in 
Utroque  cafu  fine  dubio  eadem  eft,  et  digna  quje  exploretur.  Obfervatu  quoque  dignum  eft,  quod  idem 
reperiatur  t-ffeftus,  quamvis  ftratum  calcareum  fub  fchifto  collocatum  fit  et  majori  ideo  ponderfi  comprimentc 
onuftum. -Bergman  de  Produftis  Vulcaniis  Opufcula,  torn,  iii^  p.  239.  ,. 

§  "  It  is  found  (the  furturbrand)  in  many  parts  of  Iceland,  generally  in  the  mountains,  in  horizontal  beds; 
fometimes  more  than  one  is  to  be  met  with,  as  in  the  mountain  of  Lack  in  Bardeftrand,  where  four  flrata  of  • 

iurturbrand  are  found  alternately  with  different  kinds  of  Jdone.,''— Troil's.Lctters,  p.  44,  ,, 


2o8  the  Development  of  Car  hit  In  vegetable  Matter. 

to  reft  on  the  volcanic  nature  bf  Iceland ;  but  it  furely  would  be  going  too  far  were  we  t« 
afcribe  to  fire  all  the  phenomena  which  are  obferved  in  volcanic  countries. 

Bovey  coal,  lilce  the  furturbrand,  refembles  half-charred  wood ;  and  I  will  allow,  and  in- 
deed am  difpofed  to  believe,  that  it  is  in  a  ftate  nearly  fimilar  j  but  from  this  it  does  not  follow 
that  fire  has  been  the  caufe. 

Carbon  is  known  to  be  one  of  the  grand  principles  of  vegetables,  and  alfo  as  that  which  is 
the  mod  fixed,  excepting  the  fmali  portion  of  the  earths  contained  in  them.  As  a  fixed  prin- 
ciple, carbon  appears  to  form,  in  great  meafure,  the  vegetable  fibre  ;  and  after  a  certain  de- 
gree of  combuftion,. (by  which  the  other  principles  have  been  diflipated,)  it  remains,  and  the 
particles  of  it  keep  the  fame  arrangement  which  they  poflcfl'ed  when  the  vegetable  was  com- 
plete. If,  however,  the  combuftion  has  been  carried  on  with  the  free  accefs  of  air,  the 
carbon  enters  into  combination  with  oxygen  and  caloric,  and  forms  carbonic  acid. 

We  have  many  examples  in  which  carbon  is  formed  or  rather  liberated  from  thofe  fub- 
ftances  with  which  it  was  combined  in  vegetables  ;  and  thefe  are  now  explained  as  efFe£ts 
fimilar  to  thofe  of  combuftion,  although  fire  has  not  been  the  caufe.  In  both  cafes  the  car- 
bon has  been  freed  from  the  more  volalile  principles  ;  and  under  circumftances  not 
favourable  to  the  union  of  carbon  with  oxygen,  the  former  muft  neceflkrily  remain  more  or 
lefsundiminiflied. 

During  the  combuftion  of  vegetable  matter,  the  more  volatile  principles  contained  in  the 
vegetable  fibre  (which  with  carbon  alfo  form  the  refinous  and  other  fimilar  fubftances)  ap- 
pear to  be  firft  feparated ;  and  in  proportion  to  this  feparation,  the  other  more  fixed  fub- 
llance,  which  we  call  carbon,  is  developed. 

Thus,  by  the  progrefs  of  combuftion,  wood  becomes  brown,  and  afterwards  black ;  fo 
that  the  ftate  of  the  wood  fhews  the  degree  of  combuftion  to  which  it  has  beenfubjeded,  or, 
in  other  words,  how  far  the  feparation  of  the  other  principles  from  carbon  has  been 
ciFe<aed. 

Combuftion  is  therefore  a  fpecies  of  analyfis  by  which  the  principles  of  vegetables  are 
feparated,  according  to  their  affinities,  and  according  to  their  degree  of  volatility.  By  this 
operation  hydrogen  and  azote  (if  it  be  prefent  in  the  vegetable)  are  firft  difengaged  and  form 
new  combinations,  while  the  carbon  is  the  laft  which  is  a£led  upon  j  fo  that  unlefs  a  fufficient 
ijuantity  of  oxygen  be  prefent,  it  remains  fixed  and  unchanged. 

But  the  fame  feparation  of  the  vegetable  principles  happens  whenever  vegetables  in  the 

full  pofleffion  of  their  juices  areexpofed  to  circumftances  which  favour  the  putrid  fermenta- 

.  tion. — As  in  combuftion,  fo  by  the  progrefs  of  putrefa(fl:ion  does  the  vegetable  lofe  its  colour, 

become  brown,  and  afterwards  black ;  at  the  fame  time  a  gas  is  difcharged,  which  is  com- 

pofed  of  hydrogen,  azote,  and  carbonic  acid. 

When  combuftion  is  long  continued  with  the  free  accefs  of  air,  the  whole  of  the  carbon  is 
difiipated  in  the  ftate  of  carbonic  acidj  but  in  the  procefs  of  putrefacftion  a  confiderable 
portion  of  carbon  commonly  remains  even  long  after  the  putrid  fermentation  has  ceafed. 
Although,  therefore,  it  is  as  readily  developed  by  putrefaction  as  by  combuftion,  it  is  not, 
however,  when  liberated  from  the  other  principles,  fo  fpeedily  diflipated  by  the  former  as  by 
the  latter  procefs. 

According  to  the  degree  of  combuftion  within  certain  limits  the  carbon  is  more  or  lefs 
apparent,  and  the  like  prevails  according  to  the  degree  of  putrefadion  j  fo  that  whenever 

the 


Carhm.'-Orj  the  Muhiplicathn  of  Experiments.  ."ZOg 

the  caufes  whicli  have  promoted  this  fpecies  of  fermentation  have  ceafed,  the  vegetable  fub- 
"^ance  will  remain  with  more  or  lefs  of  its  firft  principles,  and  with  more  or  lefs  vifible  car- 
bonic matter,  according  to  the  degree  of  putrefa£lion  which  has  prevailed,  and  the  vegetable 
fubftance  will  confequently  have  the  appearance  and  properties  of  wood  which  has  been 
'  charred  more  or  lefs. 

To  this  caufe,  therefore,  I  am  inclined  to  attribute  the  formation  and  appearance  of  the 
Bovey  coal  and  furturbrandv;  and  I  believe  that  the  portion  of  oily  and  bituminous  matter, 
which  I  have  obtained  from  them'by  diflillation,  is  nothing  more  than  the  remainder  of  the 
vegetable  oils  and  juices  which  have  been  partly  modified  by  mineral  agents  *. 

'    \_To  be  continued.  "^ 


III. 

New  Methods  of  affording^  at  an  inctinfider-ohle  E>:pence,  the  Heat  and  the  Water  required^of 
performing  Experiments  in  Che?ni/}ry.      By  Citizen  GorTONf. 

HERE  is  but  one  fure  road  to  arrive  at  truth  in  natural  philofophy,  namely,  by  con- 
fulting  nature  herfelf  by  experiment.  Independent  of  the  fagacity  neceflary  to  dire(5l  thefc 
to  objects  precifely  determinate,  and  to  combine  the  means  of  operating,  there  is  likewife  an 
art  of  performing  them,  or,  to  fpeak  more  properly,  of  giving  facility  without  diminifhing 
the  certainty  of  their  refults.  To  awaken  the  induftry  of  philofophers  \*ith  regard  to  fuch 
refources  as  may  be  obtained  for  the  multiplication  of  experiments  at  the  leaft  poflible  coft, 
muft  therefore  be  a  labour  of  utility  to  the  advancement  of  fcience.  When  Franklin  was 
afked  how  he  could  afford  the  charges  of  his  experiments  on  ele£tricity,  at  a  time  when  he 
was  far  from  being  in  circumftances  of  independence,  he  replied,  that  a  man  who  could  not 
faw  with  a  gimblet,  and  bore  with  a  faw,  was  not  fit  for  an  experimental  philofopher.  The 
fervices  which  Bergman  has  rendered  to  chemiftry,  and  particularly  to  mineralogy,  by  the 
introduftion  of  the  blow-pipe,  are  well  known.  What  a  number  of  valuable  obfervations 
would  ftill  be  wanting,  if  he  had  not  put  this  inftrument  into  the  hands  of  thofe  who  were 
unable  to  procure,  or  have  accefs  to  the  furnaces  of  the  elaboratoryl 

It  is  in  confequence  of  thefe  refleftions,  and  the  invitation  I  have  received  for  thatpurpofe, 
that  I  have  determined  to  defcribe  thefmall  manipulations  by  which  I  obtain  a  very  confider. 
able  faving  of  fuel  and  of  diftilled  water  in  chemical  experiments,  to  which  I  may  add  the 
'faving  of  time,  that  raoft  ineftimable  of  all  the  defiderata  for  experimental  rcfearch. 

*  "  Coal  not  only  forms  the  refiduum  ef  all  vegetable  fubflances  that  have  undergone  ailow  and  fmothereS 
combuftion,  that  is,  to  which  the  free  accefs  of  air  has  been  prevented,  but  alfo  of  all  putrid  vegetable  and 
animal  b«t\ies :  hence  it  is  found  in  vegetable  and  animal  manures  that  have  undergone  putrefaftion,  and  is  the 
true  bafis  of  their  ameliorating  powers  :  if  the  water  that  paffes  throHgh  a  putrefying  dunghill  be  examined,  it 
will  be  found  of  a  brown  colour;  and  if  fubjefted  to  evaporation,  the  principal  part  of  the  refiduum  will  be 
^onnd  to  confift  of  coal.  All  foils  fteeped  in  water  communicate  the  fame  colour  to  it  in  proportion  to  their 
fertility}  and  this  water  being  evaporated,  leaves  alfo  a  coal,  as  Meflrs.  Haflenfraz  and  Fourcroy  atteft."^ 
Kirwan  on  Manur«s,  p.  154,  vol.  v.  of  the  Tranfaftions  of  the  Royal  Irifli  Academy. 

+  Read  before  the  National  Inftitute  of  France,  the  16th  Brumaire,  ii»  the  year  6,  and  infcrted  in  the  »4tk 
volume  of  the  Annales  dc  Chimie,  page  3 11, 

Vot.  II.— August  1798.  f  *  -jEa 


210  ConJiruSlion  of  an  Eeommical  Laboratory. 

In  the  fecond  volume  of  the  memoirs  of  the  ancient  academy  of  Dijon,  I  gave  a  defcrip- 
tion  of  a  box  containing  a  Icind  of  portable  laboratory,  conipofed  of  a  lamp  with  three  wicks, 
difpofed  in  the  figure  of  an  equilateral  triangle,  to  form  an  internal  current  of  air,  with  fup- 
ports  for  the  different  veffels  of  digeftion,  diftiilation,  evaporation,  &c.  I  made  a  folutionr. 
of  fjjver  with  common  aqua  fortis  and  the  metal  in  an  alloyed  ftate,  which  anfwered  very- 
well  as  a  re-agent,  without  having  occafidn  for  any  other  utenfils  but  this  box  and  apothecary's, 
phials,  which  are  every  where  to  be  found.  A  number  of  thcfe  boxes  have  been  fitted  op 
by  Citizen  Dumoutier,  more  particularly  for  travellers,  and  I  have  reafon  to  think  that  they 
have  proved  ufeful.  But  this  apparatus  mud  neceffarily  be  confined  In.  'as  application,  and 
is  difTerent  from  the  objecl  I  purpofe  to  defcribe  at  prcfent. 

Ten  years  ago,  I  conftrufted  a  lamp,  on  the  principles  of  Citizen  Argand,  with  three  con, 
centric  circular  wicks,  each  having  an  interior  and  exterior  current  of  air.  The  effeiSl  fur* 
pafled  my  expectations  with  regard  to  the  intenfity  of  the  heat;  but  it  was  difficult  to  pre- 
vent the  deftruftion  of  the  hard  folder  round  the  wicks  ;.  and  the  glafs  retorts  were  frequently 
melted  at  the  bottom,  and  disfigured.  It  may  eafily  be  imagined,  that  the  quantity  of  oil  con- 
fumed  \yas  confiderable  ;  and  as  it  could  not  be  ufed  at  the  fame  time  for  giving  light,  it  hadj 
to  fay  the  truth,  no  more  than  a  remote  application  to  the  objefl.'  of  the  prefentcommuni- 
•ation. 

A  Ihort  time  afterwards  it  occurred  to  me,  to  fubftitutCi  inftead  of  the  glafs  chimney  of 
Argand's  lamp,  a  cylinder  of  copper  with  an  indented  part  or  ledge  a  few  millimetres  *  above 
the  flame,  to  perform  the  office  of  the  indented  chimney  of  glafs,  and  by  that  means  to 
render  it  practicable  to  raife  the  wiek  to  a  certain  height  without  fmoking.  This 
cylindfeF  has  three  branches  like  a  chaffing-dilh.  By  this  apparatus  two  or  three  decilitres 
of  water  (about  half  an  Englifll  wine  pint)  may  be  brought  to  boil  in  a  copper  or  glafs  veflel 
in  about  fix  or  feven  minutes.  It  has  ferved,  and  1  ftill  ufe  it,  for  a  number  of  operations  ;, 
but  it  was  not  till'  after  I  had  obferved  the  degree  of  heat  obtained  from  the  kmp  in  its  ordi- 
nary ftate,  and' particularly  fince  \  have  fubftituted  inftead  of  the  metallic  tube  a  chimney  of 
glafs  cut  off  at  the  length  of  three  centimeti-es  (rather  more  than  one  Englifh  inch)  abova 
the  contraction,  that  f  perceived  all  the  advantages  i^t  was  capable  of  affording;  and  that  by 
means  of  a  moveable  fnpport  for  the  reception  of  the  different  veffels,  which  may  be  fixed  at 
pleafure  by  a  thumb-fcrew,  this  lamp  furnace,  at  the  fame- time  that  it  gives  light,  and  con- 
fequently  without  any  additional  expence,  may  with  facility  be  ufed  for  almoft  every  one  of 
the  operations  of  chemiftry;  fuch  as  digeftions,  folutions,  cryftaHizations,  concentrations j 
the  rcClification  of  acids;  diflillations  on  the  fand-bath,  or  by  the  naked  fire;  incinerations 
of  the  nioft  refraftcry  refidues;  analyfes  with  the  pneumatic  apparatus,  or  of  minerals  by  the 
(aline  fufion,  &c.  &c.  I  have  not  hitherto  met  with  any  exception  but  for  complete  vitri- 
fications and  cupellations ;  for  even  the  diftillations^todrynefs  may  be  performed  with  fome 
precautions,  fuch  as  that  of  transferring  the  matter  into  a  fmall  retort  blown  by  the  ena- 
meller's  lamp,  and  placing  its  bottom  on  a  little  fand-bath  in  a  thin  metallic  difli. 

The  fupport,  here  mentioned,  is  fimply  a  copper  ring  eight  centimetres  (3,15  inch)in 
diameter,  which  is  raifed  or  lowered  by  Aiding  on  a  ftem  of  the  fame  metal.  It  is  defcribed 
in  the  memoirs  of  the  academy  of  Dijon  as  part  of  the  portable  laboratory;  for  which  reafon; 

.•  for  the  value  of  the  new  mcafures  and  weights  of  France,  fee  Philof.  Journal,  1.33a. 


Experiments  tuith  the  Lamp  Furnace.  tit 

itis  unneceffary  to  Tpeak  morelargely  of  itinthis  place*.  Nothing  more  was  required  but  to 
adapt  it  to  the  fqnare  iron  ftem  which  paffes  through  the  refervoir  of  the  lamp.  The  connec- 
tion is  made  by  apitce  of  wood,  in  order  that  lefs  of  the  heat  might  be  difperfed.  As  the  lantp 
itfelf  is  capable  of  being  moved  x>n  its  ftem,  it  is  eafy  to  bring  it  nearer  or  remove  it  at 
pleafure  from  the  veflsls,  which  remain  fixed;  a  circumftance  which,  independent  of  the  ele- 
vation or  deprellion  of  the  wick,  affords  the  means  of  heating  the  retorts  by  degrees,  of 
moderating  or  fuppreffing  the  fire  inftantly,  or  of  maintaining  it  for  fevera!  hours  at  a  con- 
ftant  or  determinate  inienfity,  from  the  alniolt  infenfiblc  evaporation  of  cryftallizable  folu- 
tions  to  the  ebullition  of  acids ;  properties  never  poflefled  by  the  athanor,  of  which  chemifts 
have  boafted  fo  much.  The  advantage  of  thefe  will  be  properly  valued  by  thofe  operators, 
who  know  that  the  moft  experienced  and  the  moll  attentive  chemifts  meet  with  frequent  ac- 
cidents, by  which  both  their  vefiels  and  the  products  of  their  operations  are  loft,  for  want  of 
power  in  the  management  of  the  fire. 

I  muft  here  enter  into  fome  detail,  in  order  to  eftablifli  upon  pofitive  fads  the  poflibility 
of  applying  the  heat  of  a  lamp  to  the  operations  I  have  enumerated,  as  well  as  to  communi- 
cate the  refults  of  my  experience  to  thofe  who  in  preference,  or  for  want  of  more  extenfive 
means,  may  be  inclined  to  life  this  apparatus.  I  do  not  hefitate  to  fay  in  preference  ;  for,  in 
the  beft  appointed  laboratory,  the  lamp  will  alfo  be  ufed  in  fuch  operations  as  may  be  made 
with  equal  facility  on  the  fame  quantities,  in  much  lefs  time  and  more  conveniently  than  by 
the  fire  of  a  furnace,  by  burning  in  the  former  inftancc  one  or  two  decimes  (or  penny- 
worths) of  oil  inftead  of  five  or  fix  decimes  of  charcoal.  The  proof  of  this  has  been  made 
in  the  laboratory  of  the  Polytechnic  School,  at  the  conclufion  of  my  laft  courfe. 

For  the  analyfis  of  ftones,  fuch  as  the  cryftals  of  tin,  on  which  I  operated  before  the  clafs 
at  the  feflion  of  the  firft  Mcflidor  laft,  I  ufe  the  ftiortened  chimney  of  glafs.  I  begin  by 
placing  the  mixture  in  a  capfule  of  platina  or  filver  of  feven  centimetres  (2-^  inches  Englifti) 
in  diameter.  I  place  this  capfule  on  the  fupport,  and  regulate  the  heat  in  fuch  a  manner 
that  ebullition  ftiall  take  place  without  throwing  any  portion  of  the  matter  out  of  the  veflel. 
As  foon  as  its  contents  are  perfectly  dry,  I  transfer  them  into  a  very  thin  crucible  of 
platina,  of  which  the  weight  is  not  quite  eleven  grammes  (25 2 i^  grains  Englifti),  and  its 
diameter  forty-five  millimetres  (i|-  inch  Englifti').  This  crucible  refts  on  a  fmalj  fupport 
•of  iron- wire,  which  ferves  to  contract  the  ring  ;  and  the  wick  being  at  its  grcateft  elevation, 
with  the  ring  lowered  to  the  diftance  of  twenty-five  millimetres  (p^-  inches  Englifti)  from 
the  upper  rim  of  the  glafs  chimney,  I  produce  in  lefs  than  twenty  minutes  the  faline  fufion 
to  fuch  a  degree,  that  from  the  commencement  of  the  operation  the  decompofition  proceeds 
as  far  as  to  0,70  of  the  mineral  f. 

The  fame  apparatus,  that  is  to  fay,  with  the  ftiortened  chimney,  ferves  for  oxidations,  in- 
cinerations, torrefa£lions,  and  diftillations  todrynefs. 

In  fuch  operations  as  require  a  lefs  heat,  I  leave  the  lamp  with  its  large  chimney  abfolute-  . 
\y  in  the  fame  ftate  as  when  it  is  ufed  for  illumination ;  and  by  raifing  and  lowering  either 

•  SeTeral  philofophers  who  have  fcen  this  apparatus  at  work,  having  requefted  me  to  give  a  drawing,  I  have 
accordingly  annexed  a  defcription  of  the  figures,  which  rcprefent  the  whole  together  at  the  end  of  this  memoir. 
I  think  it  may  be  called  the  Economical  Laboratory. 

f  See  the  Annales  de  Chimie,  xxiv.   132 ;  or  our  Journal,  I.  545, 

E  e  2  the 


ZTi^  Experiments  with  the  Lamp  Furnace. 

ih*  ring  which  fupports  the  vefle],  or  the  bodyof  the  lamp  if  tile  vefltls  Be-fixed  iir  communi- 
cation with  otliers,  I  graduate  the  heat>at  pleafure.     V  inegar  diftils  without  interruption  at 
fix  centimetres  (a-J-  inches  Eng'ifti)  from  the  upper  termination  of  the  chimney,  that  is  to  fay, . 
at  igcfentimetres  (7|.  inches  Englifli)   from  the  flame.     Water   is   made  to  boil   in  eight- 
minutes,  at  the  fame  height,  in  a  glafs  vefl'el  containing  five  decilitres  (one  wine  pint  Englifli),, 
and  is  uniformly  maintained  at  the  diftanoe  of  twenty-two  centimetres  (8y  inches)  from  fhe 
flame.     It  will   foon  be  ftiewn,    that  T  have  another  method  of  fupplying  chemifts   v^ith  < 
dilUlled  water;  fo  that  I  fcarcely  ever  repeat  this  operation  but  when  I  have  no  other  fup- 
ply  at  hand,  or  am  defirous  of  avoiding  all  trouble  whatfoever.     In  this  cafe,  I  obtain  two  or 
three  decilitres  (or  quarter  pint?)  of  water  in  the  courfe  of  a  winter  eveningj  without  the 
leaft  portion  of  my  time  being  employed  in  attending  to  the  operation. 

I  muft  not  in  this  place  omit  to  mention  a  flight  obfervation  which  this  procefs  has  afforded,  . 
becaufc  it  may  Icadto  ufeful  applications,  and  tends  to  point  out  one  great  advantage  of  this, 
method  of  operating ;.  namely,,  that  an  in.'iaity  ofcircumftances 'may  be  perceived,  which 
might  not  even  be  fufpected  when  the  whole  procefs  is  carried  on  within  arfurnace.  I  have 
remarked,  as  did  likewife  feveral  of  my  colleagues  who  were  ther*  prefent,  that  a  column  . 
of  bubbles  conftantly  rofe  from  a  fixed  point  of  the  retort  on  one  fide  of  the  bottom.  We 
were  of  opinion,  that  fome  particle  of  matter  was  in  that,  place  incorporated  with  the  glafs,  , 
which  had  a  different  capacity  (probably  condufbing  power)  for  heat  from  that  of  the  reft  of 
the  glafs.  In  order  to  verify  this  conjeclure,  I  endeavoured  the  following  day  to  diftil  the 
fame  quantity  of  the  fame  water  in  the  fame  retort,  after  having  introduced  a  button  of 
cupelled  filver,  weighing  nine  decigrammes  (20^- grains).-  At  the  commencement  of  the 
operation  there  was  a  fmall  ftream  of  bubbles  from  the  fame  point  as  before;  but  a  (hort 
,  time  afterwards,  and  during  the  whole  remaining  time  of  operating,  the  largeft  and  moft  in- 
cefiant  ftream  of  bubbles  rofe  from  the  circumference  of  the  button,  which  was  often  dif~ 
placed  by  the  motion;  and  in  proportion  to  the  time  the  produ£t  of  the  diftillation  was 
fenfibly  greater.  Whence  we  may  conclude,  that  metallic  wires  or  rods,  diftributed  through 
a  maft  of  water  required  to  be  kept  in  a  ftate  of  ebullition,  and  placed  a-little  below"its  fur- 
fece,  would  produce,  without  any  greater  expence  of  fuel,  nearly  the  fame  efFed  as  thofe 
cylinders  filled  with  ignited  matter  which  are  made  to  pafs  through  the  boilers  *. 

It  now  remains  tofliew  the  economical  method  of  fupplying  the  water  neceflary  for  expe- 
riments. 

When  water  is  mentioned  in  chemiftry,  pure  water  is  always  meant.  In  medical  prc- 
fcriptions  it  is  ufual  to  prefcribe  fpring  water,  though  in  many  places  the  water  of  fprings  or 
ftreams  is  more  loaded  with  felenite  or  fidphate  of  lime  than  the  well  water  of  other  places. 
The  fame  remark  may  be  applied  to  river  water,  which  is  no  doubt  more  wholefome  thaa 

•  When  we  attempt  to  reafon  on  this  curious  fa£l  of  the  metallic  buKon,  there  are  various  circumftances 
which  require  to  be  confidered.  It  does  not  feem  probable,  that  a  larger  quantity  of  a  fluid. can  be  rendered 
elaftic  by  a  given  quantity  of  heat,  unlefs  we  fuppofe  part  of  the  heat  to  have  been  wafted  in  the  former  pro- 
cefs. Does  the  metal,  by  the  excellence  of  its  condufting  power,  convey  a  portion  of  the  heat  more  readily  into 
the  mafsof  liquid  than  might  have  been  done  by  the  ordinary  procefs  of  circulation  ?  Or  is  the  thin  ftratum  be- 
neath the  button  fo  far  infulated  as  to  become  morefuddenly  elaftic,  and,  by  riling  in  that  ftate  to  the  furfece, 
to  increafe  the  rapidity  of  circulation,  and  the  number  of  points  at  which  vapour  can  efcape  ?  Would  a  tuft  of 
filver  wire  produce  the  fame  e&ft,?  &c.  &c.     N. 


Hajy  Method  of  rendering  Water  perfe^ly  pure.  113 

dite- water  of  wells  in  places  where  rdenite  or  plaifier  abounds,  but  which  are  neverthelefs 
fir  from  being  pure,  and  are  neceffarily  fubject  to  vary  according  to  the  quantity  of  raia 
water  whiciv  dilutes  that  which  has  remained  upon  the  foJuble  matter. 

Recouffe  is  therefore  bad  to  diftillation,  to  purify  the  water  employed  in  laboratories  ;  but 
if  on  the  one  hand  we  confider  the  labour  and  expence  it  rt-quires,  and  on  the  other  band  the 
quantity  which  it  is  lieceilary  to  have  in  readinefs  for  the  fmalleft  operations;  it  will  not 
appear  furprifing,  when  I  affert,  that  there  are  few  days  in  which  a  chemift  does  not  avoid 
making  fomc experiment,  or  obtain  uncertain  refults,  for  want  of  having  this  article  in  his 
ppwer.  ^  It  is  only-wi^h  diftilled  water  that  perfeft  reagents  can  be  prepared  ;  diftilled  water 
is  confumcdirt  iiitufions,  macerations,  foluiions,  and  edulcorations  ;  repeated  lotions  demand 
a-  large  quantity  of  this  fluid  ;  it  ought  to  be  ufed  even  for  rinfing  veffels  ;  and  in  order  to 
avoid  deceitful  conclufions,  it  is  even  proper  to  ufe  it  in  the  hydropneumatic  veflels. 

I  have  long  been  in  the  habit  of  fupplying  moft  of  thefe  demands  with  rain  water  ;   not  • 
•with  that  which  is  diredly  received,  though  in  faft  it  is  of  confiderable  purity,  particularly 
in  countries  where  there  is  no  reafon  to  fear  that  plaifter  fliould  rife  with  the  dud ;  but  the 
quantity  of  this  would  be  too  fmall.     I  have,  therefore,  ufed  water  colle£led  with  care  from  ^ 
the  roofs  of  houfes  after  the  rain  has  wafhed  the  furface.      1  filter  it  without  delay  ;  and  in 
this  manner  from  time  to  time  I  obtain  a  confiderable  provifion,  without  much  labour  and  at 
no  expence.     But  it  is  evident,  that  in  order  to  depend  on  the  purity  of'  this  water,   it  is^ 
neceffary  that  there  fliould  be  no  gypfeous  matter  in  the  compofition  of  the  mortar  of  the 
roof,  or  the  plaiftering  of  the  chimneys.     This  condition  does  not  obtain  at  Paris ;    info-- 
much  that  I  have  fometimes  found  the  firft  water  of  the  "gutters  more  felenitous  than  that 
of  the  Seine  in  the  time  of  floods.     I  have  thought  of  a  method  of  fuppljing  this  refource,  . 
by  a  procefs  which  may  be  ufed  in  all  countries ;  and  the  fuccefs  which  has   attended  my 
trials  renders  it  a  duty  to  communicate  it,  in  order  to  place  the  inftruments  of  analyfis  in  > 
the  hands  of  a  greater  number  of  operators. 

Rain  water  collected  from  the  roofs  of  houfes  which  hive  been  prevsoufly  wafhed,  cannot^' , 
and  in  fa£i:  does  not,  contain  any  thing  but  the  very  fmall  portion  of  fulphate  of  lime  which  • 
ithas  taken  up  during  its  contaft  with  the  plaifter  of  the  chimneys  and  the  pointing  of  the 
ridges.'    It  is  neceffary,  therefore,  to  deprive  it  of  this,  in  order  to  have  water  in  a  very  pure  - 
ftate.     For  this  purpofe  I  prepare  a  folution  of  barytes  according  to  the  procefs  *  by   which 
our  colleague  Vauquelin  has  rendered  fo  eafy  what  Bergman  attempted  with  imperfeft  fuc-  - 
cefs.     I  pour  this  folution  into  the  filtered  rain  water,   until,  after  the  precipitation  has  fub- 
fided,  the  laft  drop  exhibits  no  alteration  of  tranfparency.     I  even  add  a^mall  quantity  in  ■■ 
excefs,   which  fliews  itfelf  by  the  vinous  colour  it  gives  to  paper  coloured  with  fernambouc 
or  brazil  wood.     Thisexcefsfoon  falls  ;down  in  the  ftate  of  carbonate  of  barytes,  by  fimple  ' 
expofure  to  the  ain     The  precipitation  may  be  very  fuddenly  determined,  by  the  addition  of  : 
water  impregnated  with  carbonic  acid.     Too  much  muft  not  however  be  added,  becaufe  it-: 
would  take  up  a  portion  of  the  precipitate.     But  the  fpontaneous  evaporation  of -the  excefs  ^ 
of  gafeous  acid  in  the  open  air  would  in  this  cafe  foon  reftore  its  purity.. . 

To  judge  with  whatfacilityand.trifling  expence  the  whole  of  the  pijrc  water  fbtcxperi-;- 


*i 


'Philofophical  Journal,  I.  53;.  Dr.  H6pe  in  the  Edinburgh  Tranfailidns,  iv.  36;  informs  us,  that,  con- • 
trary  to  the  alTertions  of  many  chcmifts,  the  native  carbonate  of  barytes  may  be  deprived  of  its  acid  by  mere- 
Aeat  (,of  a  froith's  forge,  in  a  black  lead  crucible),    N, . 


214  FurificatUn  of  Wattr.'-^Lamp  Furnact, 

ments  may  be  procured,  it  is  fufficient  to  obferve,  that  by  ufing  an  aqueous  folution  of 
barytcs  of  which  thefpecific  gravity  was  no  more  than  1,0205,  the  quantity  of  15  grammes 
in  weight  (344'  grains  Englifli),  or  0,1473  cubic  metres  (4,1  cubic  inches  Englifh),  proved 
fufficient  completely  to  purify  eleven  decilitres  (2y  wine  pints  Ejiglilli)  of  water.  Cotife- 
quently  one  decilitre  or  part  of  the  fame  aqueous  folution  of  barytes  will  ferve  to  afford  74)6a, 
parts,  or  about  8  (French)  pints  of  diftilled  water. 

I  muft  add  an  obfervation,  which  is  very  proper -to  fliew  that  the  colledlion  of  r»in-water 
is  worth  the  trouble  and  care  of  procuring  it  in  ihe  circumftances  moft  favourable  to  its 
purity.  By  a  comparative  operation  on  ratn-water,  I  found  that  river  water  acquired  60 
grammes,  .or  four  times  the  quantity  of  the  fame  folution  of  barytes. 

I  have  jio  doubt  but  that  the  aqueous  folution  of  barytes  for  the  purification  of  water 
will,  in  the  courfe  of  time,  be  introduced  into  manufadories  for  dyeing.  It  will  ferve,  at  a, 
very  moderate  expence,  to  render  the  artifl;  mafter  of  the  fhades  he  means  to  produce,  with- 
out waiting  for  the  feafon  in  which  he  confiders  his  water  as  moil  pure.  I  gave  this  ad- 
vice to  a  manufacturer  wiiorrequefted  me  t«  analyfe  the  water  of  a  fmall  ftream  which  fup- 
plied  his  works. 

Thcfe  obfervations  may  alfo  probably  be  applied  to  another  purpofe.     It  is  known  that 
water  faturated  with  fulphate  of  lime  is  much  lefs  putrefcible  than  purer  water:  would  it 
not  be  of  advantage,  in  long  voyages,  to  take  a  fupply  of  water  exprefsly  loaded  with  this 
earthy  fait,  and,  when  it  is  wanted  for  ufe,  to  purify  it  three  or  four  days  before  hand  by  a 
fmall  portion  of  the  folution  of  barytes  ? 

This  folution  would  occupy  little  room,  and  be  attended  with  inconfiderable  expence. 
If  it  were  apprehended  that  a  fmall  portion  of  barytes  might  remain  in  folution,  which  would 
not  in  fa£t  be  without  danger,  as  this  eartlv  is  perceptibly  noxious,  a  proof  might  be  madej 
or,  to  fpeak  more  correftly,  the  depuration  might  be  rendered  abfolute  by  the  addition  of  a 
few  drops  of  the  folution  of  carbonate  of  foda.  All  thefe  manipulations  are  among  thofe 
which  may  be  very  eafily  praGifed  by  perfons  of  no  chemical  experience. 

Explanation  cf  the  Figures  of  the  Economical  Labor atcryi  Plate  IX. 

Figure  i.  reprefents  the  whole  apparatus  ready  mounted  for  diitillation,  with  the  tube  of 
fafcty  and  a  pneumatic  receiver. 

A  is  the  body  or  refervoir  of  the  ufual  lamp  of  Argand,  with  its  fliadc  and  glafs  chim- 
ney. The  lamp  may  be  raifed  or  lowered  at  pleafure  by  means  of  the  thumb  fcrew  B  *, 
and  the  wick  rifes  and  falls  by  the  motion  of  the  fmall  toothed  wheel  placed  over  the  waftc 
cup.  This  conftruction  is  moft  convenient,  becaufe  it  affords  the  facility  of  altering  the 
pofition  of  the  flame  with  Tegard  to  the  veffels,  which  remain  fixed ;  and  the  troublefome 
management  of  bended  wires  above  the  flame  for  the  fupport  of  the  veffels  is  avoided,  at  the 
fame  time  that  the  flame  itfelf  can  be  trought  nearer  to  the  matter  on  which  it  is  intended 
to  aft. 

D,  a  fupport  confifting  of  a  round  ftem  of  brafs,  formed  of  two  pieces  which  fcrew  to- 
gether at  about  two-thirds  of  its  height.  Upon  this  the  circular  ring  E,  the  arm  F,  and  the 
nut  G  flide,  and  are  fixable  each  by  its  refpeftive  thumb-fcrew.     The  arm  alfo  carries  a 

•  Itt  the  lamps  of  this  conftruftion  made  in  London  there  is  a  fpring  in  the  focket,  fufficiently  rigid  to  pre- 
vent the  lamp  A  from  falling  by  its  weight  when  B  is  unfcrcwcd,  I  fuppofe  Citizen  Guyton's  lamp  was  pro- 
vided .with  the  fame  convenicace,  bu<  that  by  overfight  it  may  jaot  have  been  inention«d.     N. 

moveable 


Lamp  Furnace.-^Meafures  of  Elefirictty,  2jf 

moveable  piece  H,  which  ferves  to  fufpend  the  velTeJs  in  a  convenient  (Ituation,  or  to  fecure 
their  pofition.  The  whole  fupport  is  attached  to  the  fquare  iron  ftem  of  the  lamp  by  a 
piece  of  hard  wood  I,  which  may  be  fixed  at  any  required  fituation  by  its  fcrew. 

K  reprefents  a  ftand  for  the  receivers.  Its  moveable  tablet  L  is  fixed  at  any  required 
elevation  by  the  wooden  fcrew  iVI.  The  piece  which  forms  the  foot  of  this  ftand  is  fixed 
on  the  board  N ;  but  Its  relative  pofition  with  regard  to  the  lamp  may  be  changed  by 
Aiding  the  foot  of  the  latter  between  the  pieces  O  O. 

P,  another  ftand  for  the  pneumatic  trough.  It  is  raifed  or  lowered,  and  fixed  to  its 
place,  by  a  ftrong  wooden  fcrew,  Q^ 

R  is  the  tube  of  fafety,  or  reverfed  fyphon,  invented  by  Citizen  Welter,  and  defcribed 
rn  the  third  cahier  of  the  Journal  of  the  Polytechnic  School,  p.  437  *. 

F/'g.  2.  fliews  the  lamp  furnace  difpofed  to  produce  the  faline  fufibn ;  the  chimney  oP 
glafs  fhortened  ;  the  fupport  D  turned  down  ;  the  capfule  of  platina  or  filver,  S,  placed  on- 
the  ring  very  near  the  flame. 

I''ig.  3.  The  fame  part  of  the  apparatus,  in  which,  inftead  of  the  capfule,  a  very  thin  and 
finall  crucible  o£  platina,.  T,  is  fubftituted,,  and  refts  upon  a.triangle  of  iron  wire  placed  onp 
the  ring. 

Fig.  j^,  exhibits  the  plan  of  this  laft  difpofition; 


IV. 

^h  Account  of  fame  Experiments  mnde  hy  Mr.  JoHN  CUTHBERrsON,  with  a  Vieiv  to  deter*- 
mine  an  unequivocal  Method  of  afeertaining  the  Power  of  eledrical  Machines.. 


He 


-OWEVER  great  the  influence  and  probable  importance  of  eledricity  may  appear  irv. 
a  large  clafs,  and  perhaps  in  the  whole  of  natural  phenomena,  we  ftill  find  that  a  number 
of  fundamental  experiments  remain  to  be  made.  Among  thefe  there  is  fcarcely  a  more  de- 
Crable  objeifl  than  to  determine  the  degree  of  excitation  or  quantity  of  eledlrlcity  afibrded 
by  machines,  in  proportion  to  the  furface  expofed  to  fridion.  When  phllofophers  en.r 
deavQur  to  communicate  to  each  otlier  the  indications  of  power  in  their  refpetlive  eleflrlcal^ 
apparatus,  they  either  defcribe  the  length  and  appearance  of  the  fimple  fpark  from  a  con- 
dudtor,  or  the  explofion  from  a  certain  meafure  of  coated  furface,  or  elfe  the  diftance  to 
which  the  attractive  power  of  the  prime  conduQor  is  rendered  perceptible  upon  a  thread 
or  pendulous  body.  The  firft  of  thefe  methods  is  fubjeft  to  variation  from  the  magnitude 
of.  the  conductor  itfelf,  the  figure  of  its  termination,  and  particularly  that  undulation  of 

*  And  alfo  in  the  id  vol:  of  the  Annales  de.Chitnie,  p.  3 1 ».  This  apparatus  ferves,  in  a  great  mealiire,  to 
prevent  the  bad  effcfts  of  having  the  veff'-ls  either  perfti'^ly  clofed  or  perfectly  open.  Slippofe  the  upper  bell- 
ihaped  veffcl  to  be  nearly  of  the  fame  magnitude  as  the  bulb  at  the  lower  end  of  the  tube,  and  that  a  quantity 
of  water,  or  other  fuitable  fluid,  fomewhat  left  than  the  contenisof  that  veffel,  be  poured  into  the  apparatus-: 
In  this  fituation,  if  the  elafticity  of  the  contents  of  the  vcffels  be  kfs  than  that  of  the  external  air,  the  fluid  will 
defcend  into  the  bulb,  and  atmo'phcric  air  will  follow  and  pals  through  the  fluid  into  the  vtflels  :  but,  oa 
the  contrary,  if  the  elafticity  of  the  contents  be  greater,  the  fl»]|d  will  be  either  fuftaintd  in  the  tube,  or  driven 
into  the  bell-fliaped  veffel;  and  if  the  force  be  ftrong  enough,  the  gaftous  matter  will  fafs  through..the  liuid,, 
{H)d  ip  part  cfcape,    N-. 

*•  which 


.»fi$  On  iht  tifual  Mea/ures  o/'E.'ciirleity: 

"vihicli  the  firfl  Account  was  given  in  our  Journal,  vol.  i.  page  83  :  and  the  lafl  method,  be- 
ing fubjefl  to  modification,  not  only  from  the  ftruCture  of  the  lefs  eflcntial -parts  of  the 
machine,  but  alfo  from  the  dimenfions  and  figure  of  the  apartment  in  which  the  experi- 
jments  are-nitfde,  has  bcen-accordingly  very  little  ufed,  Elc£lvicians  have,  therefore,  with 
confiderable  reatfon,  been  difpofed  to  avail  thenvfelves  of  the  fecond  method,  according  to 
the  fimple  coiTiputation  defcribed  in  our  work  laft  referred  to,  page  87.  But  to  this  me- 
-thod  alfo  Mr.  Cuthbertfon,  the  conftruilor  of  the  great 'Teylerian  machine  at  Haerlem, 
oflc;rs  ferious  objeflions;  in.-confequence  of  which  he  took  the  trouble  to  i-epcat  fome  ex- 
periments at  my  retjueft.  Thefe  experiments,  :together  with  his  obfetvations  and  fuch  re- 
marks as  have  occurred  to  myfelf,  will  form  the  fubje(fl-  of  the  prefent  memoir. 

The  Honourable 'Henry  Cavendiflv,  Efq.,  from  a  feries  of  experiments  upon  the  charges 
of  eleflrical  jars  *,  has  deduced,  that  the  quantities  of  eleilticity  which  coated  glafs  of  dif- 
>ferent'£hapes  and  fezes  will  receive  with  the  fame  degree  of  eletlrization,  are  diredlly  as 
the  ares  of  thecoating,  and  inverfely  as  the  thicknefs  of  the  glafs;  and  that,  when  the  in- 
fteiluties  vary,  the  quantities  of  ele<3:ricity  in  like  circumftances  are  nearly  as  the  length  of 
the  fpark.  Mr.'Guthbertfoii's  great  experience  has  led  him  to  modify  thefe  general  con- 
clufions.  I  have  found  that  in  great  intenfities  the  length  of  the  fpark  is  much  more  than 
in  proportion  to  the  charge  f  ;  andfrom  fome  fa£ls  hereafter  to  be  related,  there  is  reafon 
.to  think  that  a  real  charge  of  low  intenfity  cannot  be  meafured  either  by  the  length  of 
its  very  (hort  fpark,  or  e^/en  by  the  number  of  turns  of  the  machine.  Eleftricians,  in  ge- 
neral, ufe  the  beft  glafs  they  can  procure  in  their  vicinity;  whence  their  conclufions  are, 
'fur  the  moft  part,  applicableto  one  kind  of  glafs  only.  But  Mr.  Cuthbertfon  has  obferved, 
that  the  difterent  kinds  of  yfh'tte  glafs,  and  (till  more  the  green,  will  require  very  different 
■  quantities  of  eleftricity  to  charge  equal  furfaces  and  thicknefTes  to  the  fame  height.  He 
ihowed  me  a  jar,  of  which  the  coating  had  been  cut  away  until  its  capacity,  as  determined 
by  the  number  of  turns  of  the  machine,  became  equal  to  that  of  another  fimilar  jar  of  the 
fame  thicknefs.  The  coated  furface  of  the  former  of  thefe  two  jars  might  be  eftimated  at 
•more  than  one-third  part  lefs  than  that  of  the  former.  Hence  the  neceflity  of  fome  other 
teft;  of  cleftrical  power,  different  from  that  which  includes  the  dimenGons  of  the  jar  as  one 
of  its  elements,  is  evident.  Mr.  C.  offers  the  explofion  of  fteel  wire  for  this  purpofe;  the 
refult  of  the  fa£ls  obferved  by  him  being,  that  equal  quantities  of  eleftricity,  in  the  form  of 
a  charge,  will  caufe  equal  lengths  of  the  fame  fleel  wire  to  explode,  whether  the  jar  made 
;ufe  of  be  of  greater  or  lefs  capacity,  within  certain  limits  very  eafily  comprehended  in  a 
loofe  verbal  defcription.  The  primary  obje£l  of  Tiis  experiments  was  directed  to  the  efta- 
blifhmcnt  of  this  propofition. 

July  6th,  1798,  I  waited  on  Mr.  Cuthbertfon  at  feven  in  the  evening,  and  found  two 
eledtrical  machines  in  a  flate  of  aiStivity.  The  firft  confided  of  a  glafs-plate  24  inches  in 
diameter,  rubbed  by  two  pair  of  cufhions,  each  5  inches  long,  proceeding  from  the  extreme 
of  the  circumference  towards  the  centre  upon  oppofite  radii,  whence  the  whole  furface 
rubbed  in  each  turn  was  1193,8  fquare  inches,  or  8,29  fquare  feet.  The  other  machine  was 
of  the  fame  dimer,fions,  but  had  two  plates  and  four  pair  of  cufhions.  Ajar  fitted  up  with 
Lane's  eleftrometer,  the  balls  of  which  were  invariably  fixed,  was  ufed  to  afcertain  the 
iteadinefs  of  the  excitation.    When  this  jar  was  applied  to  the  prime  conduftor  of  the 

*  Philofophical  Tranfaftions,  Ixvi.  p.  196.  f  Phil.  Tranf.  Ixxvi. 

ilngle 


Meafure  of  EleBr'icity  iy  the  E>tplofton  of  Wirt*     -■  217 

'fingle  plate-machine,  it  exploded  five  times  in  1%  turns  of  the  winch.  Upon  applying  the 
fame  teft  to  the  double  plate-machine  it  was  found  to  afford  very  nearly,  or  rather  more 
than  twice  the  quantity  of  electricity.  All  the  following  experiments  v/ere  made  with  the 
(ingle  "plate. 

A  jar  *,  No.  i,  was  applied  to  the  prime  conduflior :  after  four  turns  fome  ramified 
flaflies  ftruck  into  the  uncoated  part,  and  at  the  fixth  turn  a  fpontaneous  exploflon  took 
place  over  the  clear  glafs.  It  muft  be  remarked,  that  the  mouths  of  none  of  the  jars  had 
any  flopper  or  covering.  Mr.  C.  then  took  a  glafs  tube,  which  he  inferted  into  the  jar 
nearly  to  the  bottom,  and  breathed  twice  through  it,  in  order,  as  he  faid,  to  render  it  more 
capable  of  retaining  its  charge.  This  procefs,  fo  contrary  to  the  received  opinion  of  elec- 
tricians, who  carefully  avoid  all  dampnefs,is  confidered  by  him  as  of  the  fame  nature  as  the 
experiment  of  Brook,  who  found  that  a  jar,  the  naked  part  of  which  was  foiled  by  handling, 
would  retain  fix  times  the  charge  without  exploding,  which  it  would  have  held  if  perfect- 
ly clean  \.  I  had  always  confidered  this  laft  experiment  as  a  proof  that  glafs,  when  greafed 
by  handling,  does  not  attraiSl  vapour  from  the  air  as  readily  as  when  clean  ;  and  accordingly 
1  have  often  ufed  tallow  as  a  good  extemporaneous  varnifli  for  glafs  pillars.  Mr.  Cuthbert- 
fon's  procefs,  however,  had  the  fame  effeft ;  for  the  jar  did  not  afterwards  exhibit  any  flafli  or 
difpofition  toexplode  during  thewhole  evening,  though  itwasoccafionallychargedwith  ten  and 
twelve  turns.  A  brafs  ball  fupported  on  a  (land  by  a  flick  of  glafs  was  placed  fo  as  to  receive 
the  explofion  from  the  jar  No.  i,  when  thus  connedled  with  the  prime  condudtor.  From 
this  ball  hung  a  fmall  piece  of  pendulum  wire  f,  confined  at  each  end  between  fmall 
forceps  conflrufled  for  that  purpofe.  The  clear  portion  of  the  wire  which  formed  part  of 
the  circuit  was  cxaftly  five  inches  in  length.  An  explofion  was  pafled  through  a  moderate 
interval  or  length  of  fpark  ;  and  this  interval  was  gradually  increafed  till,  at  lafi,  the  fliock 
became  fo  flrong  as  completely  to  ignite  the  wire  and  divide  it  near  the  pofitive  end, 
where  a  fparkling  globule  or  two  flew  out ;  ten  turns  of  the  machine  were  required  to  pro- 
duce this  effeft,  and  the  length  of  the  explofive  fpark  was  i|  inch. 

Another  jar,  No.  2  §,  was  applied  to  the  prime  conduftor  along  with  No.  r,  and  their 
outfide  coatings  were  connefted  together.  The  fame  quantity  of  wire  as  in  the  laft  ex- 
periment was  placed  in  the  circuit,  and  by  the  fame  method  an  explofion  was  obtained, 
which  ignited  and  broke  the  wire  with  nearly  the  fame  appearances  as  before.  In  this  cafe 
the  number  of  turns  were  9y,  and  the  length  of  fpark  ^  of  an  inch. 

Thefe  experiments  evidently  confirm  the  refult  Mr.  Cuthber'tfon  obtained  from  his  former 
trials  ;  namely,  that  the  quantity  of  cleftrlcity  to  difpCrfe  a  given  portion  of  wire  will  be 

•  Height  of  the  coating  7I  inches,  diameter  6J  inches,  both  outfide  meafure.  Uncoated  part  4I  inches 
perpendicular,  though  the  mouth,  in  reality,  was  fomewhat  fmaller  than  the  body  of  the  jar.  Thicknefs  o,iS 
inch.    Hence  the  furface  was  about  18S  fquare  inches,  or  \\  fquare  foot. 

t  Mifcellaneous  Experiments  and  Remarks  on  Eleftricity,  &c.  by  A.  Brook.    Norwich,  17S9. 

X  This  wire  is  fold  at  the  watch-tool  makers.     It  is  of  fteel  flattened,  and  is  ufed  to  make  the  fmall  fpting. 
■of-the  balarice  in  watches.   The  wire  here  mentioned  is  0,005  '"^^  '"^  breadth  and  one  grain  in  weight ;  meafures 
44I  inches  long. 

§  Height  of  the  coating  S I  inches,  diameter  6,1  inches,  both  outfide  meafure.  Uncoated  part  3 J- inches 
perpendicular,  though  the  mouth  was,  as  in  No.  i,  fomewhat  fmaller  than  the  body  of  the  jar.  Thick- 
nefs 0,17  inch.  Hence  the  furface  was  about  190  fquare  inches,  or  ij  fquare  foot,  nearly  the  fame  as  the 
ether  jar. 

Vol,.  II.— August  1798.  F  f  the 


9kv8.  MeafUre  of  Ele.Uricity  by  the  Explofun  oj  JVirc, 

the- fianTr,.cyen- though  the  charged  furface  (liould  be  greatly  varied.     But  it  appeared,. tie*' 
firable  to  afcertain  the  proportional  quantities  of  eleclriclty  required  to  explode  different 
lengths  of  the  fame  wire.     For  this  purpofe  2,3  iitchcs  of  wire  were  exploded  by  the  jar 
No.  I,  by  five  turns  of  the  winch;  which  was  probably  too  great  a  quantity,  for  the  ignitioa 
was  very  (trong,  and  deflagrating  globules  were  thrown  about.     But  by  a  more  careful  re- 
petition of  the  experiment  with  i\  inchss  of  wire,  the  ignition  and  partial  melting  of  the-, 
wire  were  very  nearly  the  fame  as  in  the  experiments  which  had  been  made  on  lengths  of. 
five  inches.     From  thefe  experiments  there  fcems  reafon  to  fuppofe  that  the  quantities  o€, 
■  fjleftricity  may  be  as  the  lengths  of  the  -wires  exploded. 

A  battery  of  fifteen  jars,.Gont;uning  about  17  fquare  feet  of  coated  furface,  was  tligii- nfed.», 
to  explode  five  inches- of  the  wire.  Nineteen  turns  rendered  the  wire  faintly  rqd  hot;  but,, 
20  turns  caufed  it  to  explode  in  the  fame  nifiiiner  as  in  the  experiments  with  the  jars. 

Half  the  lengthaf  wire,  namely  at  inches^  was  in  the, next  place  fubmitted  to  the  ex.^, 
plofion  of  the  battery.  Twelve,  turns  ignited  the  w.irj?,  and  15  .turns  caufed  it  to  explode.i> 
with  fomev»hat  more  violence  than-in.- the^expe,rimeiits  with  the  jars,. 

At- this  fttige  of  the  pr.ocefs,.  as  the, battery  had  required  twic£  die, quantity  of  elecfiricity, 
to  produce  the  effect  which  had.before  taken, place  wlih  a  fmaJler  qiuintity  of  coated  fur- 
lace,  it  became  a  qucflion  whether  the  length  of  the  circuit,  which  was  fix  feet  on  each  fide,  .„ 
might  have  influenced  the  refults  ;■  and  alfo  whether  the  (late  of  excitation  had  become  lefs- 
iiitenfe.  For  thefe  reafons,  the  difpofitlon  of  the  apparatus  was  altered  fo  that.the,  circuiff. 
■with  the  battery  was  the- fame  as  had  before  been  ufed  with  the  jars;  aiid  the  trial  jar, 
■with  Lane's  eleflrometer,  w»as  agaifl  applied  to  afcertaLn.tlrCippwer  of  the. machine-  Five., 
explofions  wero  afforded  by  7|  turns,  as  at-  firft.:  thts:  experiment  was  twice  repeated,  atulv 
fliewed  that  the  aiTtion  of  the  machine  continued  to  be  the  fame  as  at  firfl. 

Ih  this  new  difpofitlon  of  the  battery  five  inches  of  the  wire  were  cxpofed  to  the  explofion.  ■ 
No  effedl  was  produced  by  I2  turns ;  but  by  21  turns  the  whole  of  the  wire  was  difperfed- 
in  globules  by  a  ftrong  ignition.  I  fuppqfe  that  20  turns  might  hav£  difperfed.^  it  in  ths^ 
fame  manner  as  in  tlife  firfl;  expeririient.- 

Two  inches  afid'a  half  of  the  -vvire  were  theii  placed  in  the  circuit.  This  portion  Wa&» 
HOt  affefted"  by  an  jexplofion  of  12  turns ;  but  by  13  turns  it  was  ignited  and  broken  by, 
the  diffipation  of  a  globule  or  two.  LaftJy,  one  inch  of  the  wire,  was  ex.pofed  to,  the  fhock  j,- 
it. was  ignited,  and  partly  difperfed  in  globules  by  laturns- 

The  whole  of  thefe  experiments  employed  upwards  of  three  hours,  during  the  greatcfl' 
part  of  which  time  the  machine  wasln  a<5Hon.     At  the.  conclufion  the  trial  jar  was,  applied  :., 
it  exploded  five  times  in  a  little  more  than  eight  turns.     The  trial  was  repeated  twice,  and 
fcrvcs  evidently  to  (how  the  fteadinefs  of  theexcitatign,  which  hjd  diminiftied  only  about 
-Vth  part  during  this  courfc  of  work. 

Upon  a  review  ofnhe  foi-egcing  experiments,  it  iaobvlous  that  they  woidd  require  to  be 
lepeated  and  extended,  if  the  general  courfe  of  Mr.  Cuthbertfon's  former  proceffes  were  not 
to  be  admitted  in  confirmation  af  thepofition,  that  equal  quantities.of  eledricity  will  ignite 
and  difperfe  equal  quantities  of  the  fame  wire,  without  requiring  any  particular  adjuftment, 
of  the  quantity  of  coated  furface,  provided  the  intenfity  be  confiderable.  From  the  experi- 
jnents  with  the  battery  it  feem§  reafonable  to  conclude,  that  the  quantities  of  eledrlcity  re- 
quired to  produce  like  effe«^s  upon  wire  will  be  greater,  the  lower  the  intenfity,  when  the 

quantitif 


Meafure  of  EleBricity.—'Defcrlption  of  Gibraltar.  -i\:<^ 

quantity  of  furfacc  is  greatly  increafed;  in  which  cafe  the  velocity  of  the  eleflric  fluid 
may  be  fuppofeJ  infufficient  for  tlie  whole  charge  to  exift  in  the  condu£iing  wire  at  one  amt 
the  fame  time;  or  its  impetus  may  be  Icfs ;  or,  laftly,  there  may  be  a  confiderablc  waftc 
from  the  conducing  power  of  the  air  through  tire  very  thin  ftratum  of  air  through  which 
the  explollon  at  laft  paliles.  This  laft  fuppofiiion  is  far  from  being  merely  coujeftural. 
For  by  fome  experiments  on  the  charge  of  a  plate  of  air  in  eonneftion  with  the  gold  leaf 
eleftrometer,  of  which  I  may  hereafter  give  an  account,  I  find  that  even  m  very  low  in- 
tenfities  the  elecStric  matter  will  pafs  in  a  conftant  ftream  through  intervals  of  about  one 
inch  ;  a-conclufion  ■»i'hich  nright  likewifc  hi  deduced  from  die  very  fmall  duration  of  the 
ufual  charge  in  the  prime  condu£lor. 

^Yith  regard  to  the  curious  fa£l  of  the  fpontaneous  explofion  of  a  clean  jar ;  vhlch,  when 
damped  by  breathing  into  it,  was  found  much  more  capable  of  retaining  its  charge,  there  ap- 
pears to  be  fome  difficulty  in  the  theory.  I  have  mentioned  my  fuppofition  that  Mr.  Brook's 
experiment  of  foiling  the  jar  with  The  hand,  triglit  have  fucceeded  from  the  pcrfpirable  mat- 
ter having  operated  as  a  varnifli  to  the  expuVfion -of  moifture  from  the  atr.  Mr.  Cuthbert- 
-fon's  experiment  overthrows  this  notion,  i  am  now  inclined  to  think  that  it  depends  upon 
undulation.  The  bare  furfacc  of  clean  giafs  may  become  charged  in  fucceflive  zones  of  the 
contrary  e5e6lriciLies,  as  Prieftley  anfi  others  have  fliewrn.  When  thefe  zones  have  acquir- 
ed the  requifite  interifity,  they  may  explode  into  each  other,  and  produce  an  undulation  in 
the  whole  charge,  which  may  greatly  favour  its  flight  through  the  interval  from  coating  to 
coating.  But  when  irhe  furface  is  covered  with  diftinft  infulated  particles  of  moillure, 
•the  efcape  from  particle  to  particle  mull  be  by  fmallev  leaps  ;  the  tranquillity  of  the  charge 
will  be  fcarcdy  at  all  difturbed  ;  and  the  fpontaneous  explofion  wiJl  not  take  place  until  the 
intenfity  has  become  fo  great,  as  to  carry  it  through  a'fpcce  equal  to  thefum  of  the  inter- 
>vals  between  any  one  rcw  of  particles  which  form  a  line  from  coating  to  coating. 


V. 

AJhtrt  Mineralogical  I)efcnption  of  the  Mountain  of  Gibraltar.     By  Majof  IMRIE. 

[Concluded  from  Page  187,  Vol.  II.] 


A' 


-T  no  great  diflance  from  where  thefe  cryftals  are  found,'upon  the  fame  fliope  of  the  moun- 
tain, but  rather  nearer  to  the  level  of  the  fea,  a  ftratum  of  argillaceous  matter  has  been  laid 
open,  divided  into  many  thin  beds,  the  broadeft  of  which  does  not  exceed  a  foot  in  thicknefs. 
Its  general  colour  is  of  a  whitifli  grey,  with  a  fmall  mixture  of  yellow ;  and  it  is  divided 
tranfverfely  by  ftraight  fepta  or  cracks,  both  fides  of  which  arc  covered  with  dendritical 
figures  of  a  yellowifti  brown  colour,  beautifully  reppefenting  the  obje£ls-of  landfcape.  At 
the  weftcm  bafe  of  the  mountain,  on  a  level  with  the  fea,  by  which  it  is  wafted,  a  very  ex- 
tenfive  ftratum  occurs  of  the  fame  nature  as  the  "laft  defcribed,  bearing  from  north  to  fouth, 
parallel  with  and  dipping  towards  the  mountain  nearly  at  an  angle  of  40  degrees. 

In  fome  parts  of  the  weftern  Hope  of  the  mountain,  towards  the  fouth,  are  found  nefts  of 
a  dark  red  ftiivery  clay,  in  which  are  imbedded  flints  of  a  dirty  fap  green  colour :  of  thofe  ho 
regular  ftratutn  is  to  be  perceived ;  many  of  them  are  unfhapely  maffes  j  but  the^y  in  genc- 

-Ff2  .rM 


aao  Mtn'frahgkat  Account  of  Gihraltaf, 

ral  tend  to  the  rhomboidal  form,  and  arc  from  three  to  four  inches  long  by  two  or  three- 
broad,  and  an  inch  and  a  half  thick.  They  are  not  incrufted  as  the  flints  found  in  chalic,. 
nor  have  they  the  appearance  of  having  been  worn  by  attrition. 

Upon  different  parts  of  the  mountain,  towards  its  bafe,  are  found  large  quantities  of  iand 
compofed  of  different  materials,  and  affuming  various  appearances  as  to  colour.  TJie  largeft 
bank  of  this  arenaceous  matter  is  upon  the  weftern  fide  of  the  mountain,  and  confifts  of 
fmall  particles  of  cryftallized  quartz,  colourlefs,  and  perfedlly  tranfparent  per  fe,  but  of  an 
ochreous  colour  in  the  mafs  on  account  of  a  red  argillaceous  earth  which  adheres  to  them- 
The  fand  of  this  bank  is  perfeiSlly  loofe  and  uncombined  :  one  half  of  it  has  been  levelled 
into  an  extenfive  parade,  its  furfaee  having  been  combined  by  the  lime  and  rubbifh  from  the 
ruins  of  the  town.  The  fouthern  extremity  of  the  bank  is  ftill  to  be  feen  in  its  natural  ftate,, 
and  forms  the  burying-ground  of  the  garrifon. 

Upon  the  eaft  fide  of  the  mountain  is  found  another  of  thefe  banks,  of  confiderable  extent,, 
and,  as  I  mentioned  before,  rifing  from  the  Mediterranean  in  a  rapid  acclivity,  and  reach- 
ing to  one-third  of  its  entire  elevation.  This  bank  is  compofed  of  fmall  particles  of  cryftal- 
lized quartz,  of  teftaceous  bodies  rounded  by  attrition,  and  of  a  few  minute  particles  of  the 
calcareous  rock  ;  the  whole  has  a  whitifh  grey  colour.  The  rain-water  which  falls  from 
the  bare  mountain  rock  above  the  fand  brings  along  with  it  calcareous  matter,  which  is  de- 
pofited  upon  the  bank,  and  combines  its  furfaee  into  a  cruft,  which  in  fome  places  is  fo- 
much  indurated  as  to  bear  the  preflure  of  the  foot. 

In  other  parts  of  the  mountain  where  this  fand  is  furrounded  by  the  calcareous  rock,  and 
covered  in  and  prote6ted  from  the  a£lion  of  the  air  and  corrofion  of  fea-falts,  it  is  found  in; 
a  perfedl  indurated  f}ate,  combined  by  flaladlitical  fpar,  and  forming  a  minute  breccia.  A 
quarry  of  this  arenaceous  ftone  has  been  opened  upon  the  fouth-eaft  quarter  of  the  moun- 
tain, and  is  made  ufe  of  with  great  propriety  to  line  the  embrafures  of  fome  of  the  new 
works  belonging  to  the  garrifon.  Its  inaptitude  to  fly  off  in  fplinters  when  ftruck  by  a 
ball  gives,  in  fuch  fituations,  additional  fafety  to  the  defenders  of  the  place. 

The  weftern  fide  of  the  mountain's  bafe  around  Rofia  Bay,  and  the  New  Mole,  is  a  rock 
compofed  of  an  aggregate  of  fmall  fragments  of  every  foffil  that  has  been  here  defcribed,  with 
the  addition  of  two  different  fpecies  of  marble,  that  are  probably  adventitious,  as  their  na- 
tive beds  have  not  been  found  in  the  mountain.  The  one  of  thofe  is  black,  and  the  other  of 
an  olive  green  colour..  The  whole  of  this  mixture  produces  a  moft  beautiful  breccia,  and  is 
firmly  combined  by  a  calcareous  cement  of  a  yellow  verging  towards  an  orange  colour.. 
It  is  fufceptible  of  a  high  polifh,  except  where  fragments  of  the  argillaceous  llrata  occur : 
thefe  can  be  eafily  fmoothed  down,  but  cannot  be  brought  to  a  perfe£b  polifh.  The  frag~ 
ments  in  this  breccia  are  angular,  and  none  of  them  have  the  appearance  of  being  water- worn. 

It  only  now  remains  for  me  to  mention,  what  are  generally  called  the  foffil  bones  found 
in  the  rock  of  Gibraltar.  Thefe  have  been  much  talked  of,  and  by  fome  looked  upon  as  a., 
phenomenon  beyond  the  power  of  explanation.  The  general  idea  which  exifts  concerning 
them  is,  that  they  are  found  in  a  petrified  flate  and  inclofed  in  the  folid  calcareous  rock  ;  but 
thefe  are  miftakes  which  could  only  arife  from  inaccurate  obfervation  and  falfe  defcrip.^ 
tion. 

In  the  perpendicular  fiffures  of  the  rock,  and  in  fome  of  the  caverns  of  the  mountain  (all 
•f  which  afford  evident  proofs  of  their  former  communication  with  the  furfaee),  a  calcarcour 

concretion 


FoJJil  Bones,  ^c.  in  tU  Roei  of  Gibraltar,  at  I 

concretion  is  found  of  a  reddifli  brown  ferruginous  colour,  with  an  earthy  frailure  and  con- 
fiderable  induration,  inclofing  the  bones  of  various  animals,  fome  of  which  have  the  appear- 
ance of  being  human.  Thefe  bones  are  of  various  fizes,  and  lie  in  all  dire£lions  intermixed 
with  fliells  offnails,  fragments  of  the  calcareous  rock,  and  particles  of  fparj  all  of  which 
materials  are  ftill  to  be  feen  in  their  natural  uncombined  ftates,  partially  fcattered  over  the 
furface  of  the  mountain.  Thefe  having  been  fwept  by  heavy  rains  at  different  periods  from 
the  furface  into  the  fituations  above  defcribed,  and  having  remained  for  a  long  feries  of  years 
in  thofe  places  of  reft,  expofed  to  the  permeating  aftion  of  water,  have  become  enveloped 
in,  and  cemented  by,  the  calcareous  matter  which  it  depofits. 

The  bones  in  this  compofuion  have  not  the  fmalleft  appearance  of  being  petrified ;  and  if 
they  have  undergone  any  change,  it  is  more  like  that  of  calcination  than  that  of  petrifac- 
tion, as  the  moft  folid  parts  of  them  generally  admit  of  being  cut  and  fcraped  down  with  the 
fame  eafe  as  chalk. 

Bones  combined  in  fuch  concretions  are  not  peculiar  to  Gibraltar ;  they  are  found  in 
fuch  large  quantities  in  the  country  of  Dalmatia,  and  upon  its  coafts  in  the  iflands  of  Cherfo 
and  Ofero,  that  fome  naturalifts  have  been  induced  to  go  fo  far  as  to  aflert,  that  there  has 
,  been  a  regular  ftratum  of  fuch  matter  in  that  country,  and  that  its  prefent  broken  and  inter- 
rupted appearance  has  been  caufed  by  earthquakes  or  other  convulfions  experienced  in  that 
part  of  the  globe.  But  of  late  years,  a  traveller  (Abbe  Alberto  Fortis)  has  given  a  minute 
defcription  of  the  concretion  in  which  the  bones  are  found  in  that  country  :  and  by  his  ac- 
count it  appears,  that  with  regard  to  fituation,  compofition,  and  colour,  it  is  perfedly  fimilar 
to  that  found  at  Gibraltar.  By  his  defcription  it  alfo  appears  that  the  two  mountain  rocks 
of  Gibraltar  and  Dalmatia  confift  of  the  fame  fpecies  of  calcareous  ftone ;  from  which  it  is 
to  be  prefumed  that  the  concretions  in  both  have  been  formed  in  the  fame  manner  and  about 
the  fame  periods. 

Perhaps,  if  the  fiflures  and  caves  of  the  rock  of  Dalmatia  were  ftill  more  minutely  exa- 
mined, their  former  communications  with  the  furface  might  yet  be  traced,  as  in  thofe  de- 
fcribed  above ;  and  in  that  cafe,  there  would  be  at  leaft  a  ftrong  probability  that  the  mate- 
rials of  the  concretions  of  that  country  have  been  brought  together  by  the  fame  accidental 
caufe,  which  in  my  opinion  has  coUeded  thofe  found  in  the  caverns  of  Gibraltar.  I  have 
traced  in  Gibraltar  this  concretion,  from  the  loweft  part  of  a  deep  perpendicular  fifTure  up  to- 
the  furface  of  the  mountain.  As  it  approached  to  the  furface,  the  concretion  became  lefs 
firmly  combined;  and  when  it  had  no  covering  of  the  calcareous  rock,  a  fmall  degree  of  ad- 
hefion  only  remained,  which  was  evidently  produced  by  the  argillaceous  earth  in  its  compofi- 
tion having  been  moiftened  by  rain  and  baked  by  the  fun.  ^ 

The  depth  at  which  thefe  materials  had  been  penetrated  by  that  proportion  of  ftala£titical 
matter,  capable  of  giving  to  the  concretion  its  greateft  adbefion  and  folidity,  I  found  to  vary 
according  to  its  fituation,  and  to  the  quantity  of  matter  to  be  combined.  In  figures  nar- 
row and  contraiSted,  I  found  the  concretion  pofleffing  a  great  degree  of  hardnefs  at  fix  feet 
from  the  furface  ;  but  in  other  fituations  more  extended,  and  where  a  larger  quantity  of  the 
materials  had  been  accumulated,  I  found  it  had  not  gained  its  greateft  degree  of  adhefion  at 
double  that  depth.  In  one  of  the  caves  where  the  mafs  of  concretion  is  of  confiderable  fize, 
I  perceived  it  to  be  divided  into  different  beds,  each  bed  being  covered  with  a  cruft  of  the 
ftalaftitical  fpar  from  one  inch,  to  an  inch  and  a  half  in  thicknefs ;  which  feems  to  indicate, 

that 


*2ii  TrohnhhOrlglti  of  the  FoJllBone:  at  Gibraltar. 

'  ttiat  thc'mriteriais  had  been  carried  in  at  various  periods,  and  that'  thofe  periods  baVebeen 
'very  remote  from  each  other. 

•  ArUofia  Bay,  upon  the  Wfeft  fitJe  of  Gibraltar,  this  cbtierelion'  is  found  in  what  has  evi- 

•  dently  been  a  cavern,  Originally  formed   by  huge  unfhapely  maffes  of  rock,   which   have 

•  tuiTibled  in  together.  The  filTure  or  cavern  formed  by  the  difniption  arid  fubfidence  of  thofe 
mafles  has  been 'entirely  filled  tip  wMth  the  toncretion,  and  is'nov/  expofed  to  full  view  by 
the  outward  mafs  having  dropped-down  in  ccftifetjuence  of  the  encroachments  of  the  fea.    It 

■  isto  this  fpotthat  ftrangtrs  are  generally  led  to  examine'the  piienomenon;  and  the  compo- 
fition  having  here  attained  toils  greateft  degree  of  hardnefs  and  folidity,  the  hifty  obfcrver, 

"feeing  the"  bones -entlofedln  what  has' fo  little"  the  appearance  of  having  been  a  vacuity,  ex- 
amines no  farther,  but  immediately  adopts  tlic  idea' of  their  being  incafed  in  the  folid  rock. 
'The  con>munication  from  this- former  chafm  to  the  furfacc,  from  whicn  it  ha?  received  the 
materiaJs-of  the  concretion,  is  {Vill  to  be  traced  in  the  face  of  the  rock;  but  its  opening  is  at 
prefent  covered  by  ihe''bafe  of  the  Tine  wali  ttf  the  garrifon.  Here  bones  are  found  that  ate 
apparently  human;  and  thofe  of  them  tliat  appear  to  be  of  the  legs,  arms,  and  vertebras  of  the 
back,  are  fcattercd  among  others  of  various  kinds  and  fizes,  even  down  to  the  fmalleft  bones 
of  fmalT  birds.  IFound  here  the  complete  jaw-bone  of  a  flieep  ;  it  contained  its  full  com- 
plement of  tee'tb,  the  enamel  of  which  was  perfect,  and  its  whitenefs  and  luflrein  ho  de- 
gree impaired.    'In 'the  hollow  parts  of  fome  of  the  large  bones  was  contained  a  minute 

•  cryftallfzation  of^pure  and  colourlefs  calcareous  fpar ;  but  in  mofl;  the  interior  part  confifted 
<  of  a  Tparry  cruft  of  a  reddifh  colour,  fcarcely  in  any  degree  rranfparent. 

'At  the  northern  extremity  of  the  mountain  the  concretion  is  generally  found  in  perpen- 
dicular fiffures.  The  miners  there  employed  upon  the  fortifications,  in  excavating  one  of 
thofe  fifllires,  found,  at  a  great  depth  from  the  furface,twoflculIs,  which  were  fuppofed  to  be 
human  ;  but  to  me  one  of  them,  if  iTOt  both,  appeared  to  be  too  fmali  for  the  human  fpecies. 
The  bone  of  each  was  perfeflly  firm  and  folid;  from  which  it  is  to  be  prefumed  that  they 
were  in  a  ftate  of  maturity  before  they  were  encldfed  in  the  concretion.  Had  they  apper- 
tained to  very  young  children,  perhaps  the  bone  would  have  been  more  porous,  and  of  a  lefs 
firm  texture.  The  probability  is,  that  they  belonged  to  a  fpecies  of  monkey  which  ftill  con- 
tinues to  inhabit  in  confiderable  numbers  thofe  parts  of  the  rock  which  are  to  us  in- 
acceffible. 

This  concretion  varies  in  its  compofition  according  to  the  fituation  in  which  it  is  found. 
At  the  extremity  of  the  Prince's  lines,  high  in  the  rock  which  looks  towards  Spain,  it  is  found 
to  confift  only  of  a  reddifli  calcareous  earth,  and  the  bones  of  fmall  birds  cemented  thereby. 
The  rock  around  this  fpot  is  inhabited  by  a  number  of  hawks,  that  in  the  breeding  fcafon 
neftle  here  and  rear  their  young:  the  bones  in  this  concretion  are  probably  the  remains  of 
the  food  of  thofe -birds.  At  the  bafe  of  the  rock  below  King's  lines  the  concretion  confifts 
of  pebbles  of  the  prevailing  calcareous  rock.  In  this  concretion,  at  a  very  confiderable 
depth  under  the  furface,  was  found  the  under  part  of  a  glafs  bottle,  uncommonly  fliaped,  and 
•«f  great  thicknefs ;  the  colour  of  the  glafs  was  of  a  dark  green. 

In  many  parts  of  the  rock  I  have  found  concretions  in  which  there  are  no  bones  of  any 
kind ;  and  on  the  elevated  parts  of  the  mountain,  where  the  flopes  are  rapid,  I  have  found  a 
breccia  (if  I  may  fo  call  it)  entirely  confifting  of  fnail-fhells  combined  in  a  mafs  of  opaque 
ftala<Sitical  fpar  of  a  yellowifli  brown  colour.    The  various  progrellive  augaientations  of  this 

matter 


Difcovery  cf  Native  Goid  hi  Inland,  22  J^ 

matter. W£re  to  be  traced  in  various  fliadcs  of  the  fame  colour,  which,  like  the  zones  of  the 
antique  alabafter,  curve  round  and  follow  the  form  of  the  fhell.     The  purer  matter  of  this . 
fpar  has  penetrated  the  (hells,  and  in  their  interior  hollows  has.  formed  a  lining  of  fmall 
cryftals,  generally  colourlefs,  and  perfciSlly  tranfparint. 

I  have  beftowed   more  time  in  endeavouring  to  defcribe  the  compofition  and  the  real 
fituation  in  this  concretion  of  bones  than  the.  fubjccl,  in  tha  eftfmation  of  many,  will  feem 
to  deferve,  and,  indeed,  more  than  it  deferves  in  my  own  opinion  ;   but  where  an  erroneous  ■ 
t^inion,  has  obtained  a  footing  in  confequence  of  inaccurate  obfcryations  and  partial  de- 
foription,  .,it  is  the  duty  .of  every  new  obfcrver  to  endeavour  to  corre£l  it. 


VI. 

Accounts  of  the  Dtfcovery  of  Native  Gold  in   Ireland. 

H  E  public  attention  was  a  few  years  ago  greatly  excited  by  the  important  mineralogi- 
cal  difcovery  of  native  gold  in  Ireland;  foon  after  which  accounts  were  fent  to  the  Royr.'. . 
Society.  (Phil.  Tranf.  1796.)  It  may  caQly  be  imagined,  that  thcfe  works,  muft  have  been  i 
fufpended  by  the  convulfions  which  at  prefent  agitate  that  unhappy  kingdom.  But  as  I  hope  ■ 
by  enquiry  to  afcertain  what  has  been  done  fince  the  original  difcovery,  which  from  its  in- 
tereft  and  <:uriofity  is  highly  defer ving  of. attention,. I  fhall  hereprclciit  the  fubftaace  of  thefcs 
accounts  to  my  readers  with  very  little  abridgement. 

John  Lloyd,  Efq.  of  Havodynos,  gave   the  following  account,  dated  November  •  the 
4th,  1795: 

About  feven  miles  weftward  of  Arklow,  ialhe  county  of  Wicklow,  there  is  a  very  high' 
hill,  perhaps  fix  or  {^-zi^  hundred  yards  above  the  fea,  called  Croughan  KinQielly,  one  of  whofc  . 
N.  E.  abutments  or- buttrefles  is  called  Balinnagore,  to  wlwch  the  afcent  may  be:  made  in. 
half  or  three  quarters  of  an  hour.-    In  J-acob  Nevill's  map  of  the  coi:nty.of  Wicklow,  puh-> 
lifhed  in  1760,  by  carting  your  eye  oi>  the  river  Ovo,  which  runs  -by  Arklow,  3t:.aboiat  four 
miles  above  the  latter  place,  you  will  perceive  the-conflux  of  two  confiderable  ftreams,  and* 
of  a  third  about  half  a  mile  higher  up,  clofe  to  a  bridge.     By  tracing  this  laft  toits  fourc^,» 
you  will  come  to  a  place  fet  down  in  the  map  Ballinvally;  this  is  a  ravine  between  two 
others,- that -run  down  the  fide  of  the -hill  into-a  femi-circle,  or  more  properly  femi-elliptical 
valley,  which  extends'fn  breadth  from  one  fummit  to  the  other  of  the  boundary  of  the  valley,  > 
and  acrofs  the  valley  three  quarters  of  a  mile  or  fomewhat  lefs.     The  hollow  fid'e  of  the  hill 
forms  the  termination  of  the  valley,  and  down  which  run  the  three  ravines  abovementioned;  ■ 
At  their  jundlion  the  brook  aflumes  the  name  of  Ballinafloge:  at  this  place  the  defcent  is 
not  very  rapid,  and  fo  continues  a  hanging  level  for  about  a  quarter  of  a  mile  or  fomewhat 
more,  whett  the  valley  grows  narrower  and  t-he  fides  of  the  braok  become  fleeper ;  and  it  • 
Ihould  feem  that  fome  rocky  bars  acrofs  the  courfe  of  the  brook  .have  formed  the  gravelly  1 
beds,  above,  over,  and  through  which  the  ftream  flows,  and  in- which  the  gold  k  found.    The 
ted  of  the  brook,  and  the  adjacent  banks  of  gravel  on  each  fide,  for  near  a  quarter  of  a  mile ' 
in  length,  and  for  20  or  30  yards  in  breadth,  have  been  entirely  ftirred  and  wafhed  by  the  - 
peafants.of  the  country,  who  amounted  to  many  hundreds  at  work  at  a  time  whilft  th&y 
weic  i  erxnitted  to  fearch  for  the  metal. 

4  ,  A  geijtlemaa. . 


«a4  Acceunl  of  thj  Ir'ijh  Gold  Mine. 

A  gentleman  who  faw  them  at  work  affured  Mr.  Lloyd,  that  he  counted  above  three 
hundred  wom^en  atone  time,  befides  great  numbers  of  men  and  children. 

The  ftream  runs  down  to  the  N.  E.  from  the  hill,  which  iecms  to  confift  of  a  mafs  of 
fliiftus  and  quartz;  for,  on  examination  of  the  principal  ravine,  which  is  now  wafhed  clean 
by  the  late  heavy  rains,  the  bottom  confifted  of  fhiftus  interfedled  at  different  diftances  and 
in  various  places  by  veins  of  quartz,  and  of  which  fubftances  th'e  gravelly  beds  at  the  bottom, 
where  the  gold  is  found,  feem  to  confift. 

Large  tumblers  of  quartz  are  thickly  fcattered  over  the  furface  of  the  top  of  the  hill, 
under  a  turbary  of  confiderable  thicknefs,  upon  the  removal  of  which  thefe  tumblers  appear. 

The  gold  has  been  found  in  maffes  of  all  fizes,  from  thofe  of  fmall  grains  to  that  of  a  piece 
of  the  weight  of  five  ounces;  which  beautiful  fpecimen  is  intended  for  the  cabinet  of  a  noble- 
man adored  in  this  country,  and  not  lefs  refpefted  by  his  friends  in  England,  and  which  I  dare 
to  fay  you  will  fliortly  have  an  opportunity  of  feeing  in  London.  One  piece  of  twenty-two 
ounces  has  been  taken  up,  and  which  I  am  told  is  to  be  prefented  to  his  Majefty. 

Mr.  Graham  of  Ballycoage  informed  Mr.  Lloyd,  that  about  twenty-five  years  ago,  or 
more,  one  Dunaghoo  a  fchoolmafler,  refident  near  the  place,  ufed  frequently  to  entertain 
them  with  accounts  of  the  richnefs  of  the  valley  in  gold;  and  that  this  man  ufed  to  go  in  the 
night  and  break  of  day  to  fearch  for  the  treafure ;  and  thefe  gentlemen  with  their  fchool- 
fellows  ufed  to  watch  the  old  man  in  his  excurfions  to  the  hill,  to  frighten  him,  deeming  him 
to  be  deranged  in  his  lntelle<Sts.  However,  the  idea  of  this  treafure  did  at  laft  a(n;ually  de- 
range him. 

Mr.  Lloyd  learned  alfo  from  John  Byrne,  that  about  eleven  or  twelve  years  ago,  when  he 
was  a  boy,  he  was  fifliing  in  this  brook,  and  found  a  piece  of  gold  of  a  quarter  of  an  ounce, 
which  was  fold  in  Dublin  ;  but  that,  upon  one  of  his  brothers  telling  him  it  mufthave  been 
dropped  into  the  brook  by  accident,  he  gave  over  all  thoughts  of  fearching  for  more. 
Charles  Toole,  a  miner  at  Cronbane,  faid,  that  he  heard  of  this  difcovery  at  the  time,  but 
gave  no  credit  to  it,  as  he  never  found  any  gold,  and  lives  very  near  the  place ;  and  Mr. 
Lloyd  was  alfo  credibly  informed,  that  a  goldfmith  in  Dublin  has  every  year  for  eleven  or 
twelve  years  bought  four  or  five  ounces  of  gold  brought  conftantly  by  the  fame  perfon,  but 
not  John  Byrne. 

The  name  of  the  brook  where  the  gold  is  found  is  in  Irifli  Aughatinavought. 

The  account  of  the  mineralogy  and  other  clrcuraftances  by  Abraham  Mills,  Efq.  is  as 
follows :  * 

The  workings,  which  the  peafantry  recently  undertook,  are  on  the  north-eaft  fide  of  the 
mountain  Croughan  Klnfhelly,  within  the  barony  of  Arklow  and  county  of  Wicklow,  oii 
the  lands  of  the  Earl  of  Carysfort,  wherein  the  Earl  of  Ormond  claims  a  right  to  the 
minerals,  in  confequence  of  a  grant  in  the  reign  of  King  Henry  the  Second  by  Prince  John, 
during  his  command  of  his  father's  forces  in  Ireland  ;  which  grant  was  renewed  and  con- 
firmed by  Queen  Elizabeth,  and  again  by  King  Charles  the  Second  *. 

The  fummit  of  the  mountain  is  the  boundary  between  the  counties  of  Wicklow  and 
Wexford;  fevenEnglifli  miles  weft  from  ArkJk  w,  ten  to  the  fouth-weftward  of  Rathdrum,. 
and  fix  fouth-wefterly  from  Crojibane  mines ;  by  cftimation  about  fix  hundred  yards  above 

•  It  was  afterwards  found  that  this  grant  had  been  annulled  by  an  aft  of  the  Irifli  Parliament  near  the 
beginning  of  the  prefent  century.    Mr.  Mills  has  fince  worked  this  mine  on  account  of  Government.    N. 

6  the 


'jtccount  af  the  Ir'ijh  Gold  Mint,  jlj^ 

the  level  of  the  fea.  It  extends  W.  by  N.  and  E.  by  S.  and  flretches  away  to  the  north- 
eaftward  to  Ballycoage,  where  (hafts  have  formerly  been  funk,  and  feme  copper  and 
magnetic  iron  ore  has  been  found;  and  thence  to  the  N.  E.  where  extends  a  tra(£l  of  mineral 
country  ei^ht  miles  in  length,  running  through  the  lands  of  Baliymurtagh,  Ballygahan, 
Tigrony,  Cronebane,  Connery,  and  Kilmacoe,  in  all  which  veins  of  copper  ore  are  found ; 
and  terminating  at  the  flate  quarry  at  Balnabarny. 

On  the  higheft  part  of  the  mountain  are  bare  rocks,  being  a  variety  of  argillite  *,  whofe 
joints  range  N.  N.  E.  and  S.  S.jW.  hade  to  the  S.  S.W.  and  in  one  part  include  a  rib  of 
quartz  three  inches  wide,  which  follows  the  diredion  of  the  ftrata.  Around  the  rocks  for 
fome  diftance,  is  found  ground,  covered  with  heath ;  defcending  to  the  eaftward  there  is 
fpringy  ground  abounding  with  coarfe  grafs ;  and  below  that  a  very  extenfive  bog,  in  which 
the  turf  is  from  four  to  nine  feet  thick,  and  beneath  it  in  the  fubftratum  of  clay  are  many 
angular  fragments  of  quartz,  containing  chlorite  and  ferruginous  earth.  Below  the  turbary 
the  ground  falls  with  a  quick  defcent,  and  three  ravines  are  obferved.  The  central  one, 
which  is  the  moft  confiderable,  has  been  worn  by  torrents,  which  derive  their  fource  from 
the  bog ;  the  others  are  formed  lower  down  the  mountain  by  fprings,  which  uniting  with 
the  former,  below  their  juniflion  the  gold  has  been  found.  The  fmaller  have  not  v/ater 
fufficient  to  wafli  away  the  incumbent  clay  fo  as  to  lay  bare  the  fubftratum;  and  their  beds 
only  contain  gravel  confifting  of  quartz,  with  chlorite  and  other  fubftances  of  which  the 
mountain  confifts.  The  great  ravine  prefents  a  moft  interefting  afpcft  ;  the  water  in  its 
defcent  has  in  a  very  fhort  diftance  from  the  bog  entirely  carried  off  the  clay,  and  con* 
ftderably  worn  down  the  fubftrata  of  rock,  which  it  has  laid  open  to  infpeflion. 

Defcending  along  the  bed  of  the  great  ravine,  whofe  general  courfe  is  to  the  caftward, 
a  yellow  argillaceous  fhiftus  is  firft  feen ;  the  laminae  are  much  fhattered,  are  very  thin, 
have  a  flight  hade  to  the  S.  S.  W.  range  E.  S.  E  and  W.  N.  W.     Included  within  the  fliift 
is  a  vein  of  compaft  barren  quartz,  about  three   feet  wide,  ranging  N.E.  and  S.  W. ; 
below  this  is  another  vein  about  nine  inches  wide,  having  the  fame  range  as  the  former, 
and  hading  to  the  northward,  confifting  of  quartz  including  ferruginous  earth.     Lower 
down  is  a  vein  of  a  corhpa6l  aggregate   fubftance,    apparently  compounded  of   quart*, 
ochraceous  earth,  chert,  minute  particles  of  mica,  and  fome  little  argillite  of  unknown 
breadth,  ranging  E.  and  W.  hading  faft  to  the  fouthward,  and  including  ftrings  of  quartz 
from  one  to  two  inches  thick,  the  quartz  containing  ferruginous  earth.     The  yellow  argil- 
laceous fhiftus  is  again  feen  with  its  former  hade  and  range  ;  and  then  adjacent  to  a  quartz 
vein  is  laminated  blue   argillaceous  flilftus,    ranging  N.  E.  and  S.  W.  and  huding  S.  E.  j 
which  is  afterwards  feen  varying  its  range  and  hade,  running  E.  N.  E.  and  W.  S.  W.  and 
hadingN.  N.  W.     Lower  down,   the    blue  Ihift  is  obferved   more  compa£l,  though  ftill 
laminated.     The  ground,  lefs  fteep,  becomes  fpringy,  is  inclofed,  and  the  ravine,  (hallower, 
hasdepofited  a  confiderable  quantity  of  clay-fand  and  gravel.     Following  the  courfe  of  the 
ravine,  or,  as  it  may  now  more  properly  be  called,  the  brook,  you  arrive  at  the  road  which 
leads  to  Arklow  ;  here  is  a  ford,  and  the  brook  has  the  Irifti  name  of  Aughatinavought  (the 
river  that  drowned  the  old  man) :  hence  itdefcends  to  the  Aughrim  river,  juft  above  its  con- 
fluence with  that  from  Rathdrum,  which  after  their  jundicui  take  the  general  name  of  the 

•  Kirwan,  edit.  17941,  p.  i34- 
Vol.  IL—AvGU$T  1798.  Gg  Ovq, 


2i5  Difcovery  of  native  GjU  in  Irelaitd, 

pvo,  that,  difcharging  itfelf  into  the  fea  near  the  town  of  Afklovv,   forms  an  harbour  fc? 
Veffels  of  fmall  turthcn. 

The  lands  of  Ball'mvally  are  to  the  fouthward,  and  the  lands  of  BalRnagorc  to  the  northji 
Ward  (f  the  ford,  where  the  bTuc  (hiftiis  rock,  whofe  joints  are  nearly  vertical,  is  fcen  ran- 
ging E.  N.  E.  and  W.S.W.  including  fm.jU  ftrings  of  quartz  wi)ieh  contain  ferruginous 
earth.  The  fame  kind  of  earth  is  alfo  feen  in  the  quarts,  contained  in  a  vein  from  ten  ta 
twelve  inches  vi'fde,  ranging  E.  N.Il.  and  WiS.W.  and  hading,  to  tliefputltward,,  which  has 
been  laid  open  in  forming  the  Arklow  roa(i.' ^  '■  '    i    ^.      .  .      , 

There  the  valley  is  from  twenty  to  thirty  yv^ri^  in  wi'dt^i,  and  is  coAfered  wit-fa  fubftancea 
waftied  down  from  the  mountain,  which  An  the  fides  have  accumulated  to  the  depth  of 
iboiit  twelve  Vcet;  '■  A  thin  ftratum  of  vegetabk  foil  lies  uppermoft;  then  clay  mingled  with; 
fine  fandcompofed  of  "fmall  particles  of  quartz,  mica,  and  fhift  ;  beneath  which.the  fame 
ifwbft'aVrces  art  larger,  :aiidconftituteabeid'6f-gravel-th'at  alfocontains  nOdulfesof  fiile. grain* 
ed  iron-ft'oiie,'  which- protKices  50  per  cent.'of  lirude  ir6n  :  incumbent  oni' the  rock  are  large 
tumblers  of  quartz,'  a  variety  of  arj./illite  and  'fhi'itus  ;  many  pieces  of  the.  quartz  are  perfect* 
ly  pure;  others  are  attached  to  the  fliiftus  ;  others  contain  chlorite,, pyrites,  mica,  and  fer». 
ruginous  earth;  and' thearfenical  cubical  pyrites  frequently  occurs  imbedded  in  the  blua 
fhiftus^  In'thid  mafs  of  h:i'atter,  before  the  workings  began,  the  brook  had  formed  its  chan-. 
nel  down  to  the  furface  df  the  rock,  and  betvveen-fix  and  fevcn  feet  wide,  but  in,  times  of 
itlods  extended' itielfehtifoely  over  the  valley.  - 

Refearches  have  been  made  for  the  gold  amid  ft  the  fand  and  the  gravel  along  the  run  of 
the  brook  for  near  half  a  mile  in  length  ;  but  it  is  only  about  one  hundred  and  ^\ky  yards 
above,  and  about  two  hundred  yards  below  the  fopd,.  that' the  trials  have  been  attended  with, 
muchfucceft:  within  that  fpace  the  valley  is  tolerably  level,  and  the  banks  of  the  brox)khav« 
not  more  than  five  feet  of  fand  and  gravel  abov;?  the  rock:  added  to  this,  it  takes  a  fmall 
turn  to  the  fouthward,  and  confequently  the  rude  furfaces  of  the  fliiftus  rock  in  fome  degree 
trofs  its  courie,  and  form  natural  impediments  to  the  particlss  of  gpld  being  carried  furthec 
down  the' ftream,  which  flill  lower  has  a  more  rapid  defcent.  Befides,  the  rude  manner  ia 
which  the  country  people  worked  feldom  enabled  them  to  penetrate  to  the  rock  in  thofe. 
places  where  the  fand  and  gravel  were  of  any  material' (lepth.  Their  method  was  to  tura 
thecourfe  of  the  water  wherever  they  deemed  necefiary,  and  then'  with  any  inftruments  they, 
could  procure  to'dig  holes  down  to  the  rock,  and,  by  wafhing  in  bowls  and  iieves  the  fand 
and  gravel  they  threw  out,  to  feparate  the  particles  of  gold  which,  it  contained ;  and  from, 
flie  flovenly  and  hafty  way  in  which  their  operations  were  performed,  much  gold  moft  pro- 
bably efcaped  their  fearch  :  and  that  indeed  a£lually  appears  to  have  been  the  cafej  for,  finca 
the  late  rains  waftied  the  clay  and  gravel  which  had  been  thrown  up,,  gold  has  been  found 
lymg  on  the  furface.  The  fituation  of  the  place^  and  the  conftant  command  of  water,  do 
however  very  clearly  point  out  the  great  facility  with  which  the  gold  might  be  feparated  irom 
tiie  trarti,  by  adopting  the  mode  of  working  praftifed  at  the  beft  tin  ftream  works  in  the 
county  of  Cornwall  ;  that  is,  entirely  to  remove  (by  machinery)  the  whole  cover  off  the  rock, 
and  then  wafli  it  in  proper  buddies  and  fieves.  And  by  thus  continuing  the  operations, 
conftantly  advancing  in  the  ravine  towards  the  mountain,  as  long  as  gold  {hould  be  found, 
the  vein  that  forms  its  matrix  might  probably  be  laid  bare. 

The  difcovery  was  made  public,  and  the  workings  began  early  in  the  month  of  September 


Difc(A)ei'y  of  native  Gold  in  Inland.  ^•^ 

laft  (1795),  and  ontinued  till  the  18th  of  Odtober,  when  a  party  of  the  Kildare  militia  ar- 
rived, and  took  pol^iflion  by  order  of  goverplnent  j  and  the  great  concourfe  of  people,  wh« 
were  bufijy  engaged  in  endeavouring  to  procure  a  fhare  of  the  treafure,  immediately  defiftcd 
from  their  labour,  and  peaceably  retired. 

Calculation'!  h^ve  been  made,  that,  during  the  foregoing  period,  gold  to  the  amount  of 
three  thoufand  pounds  Irifti  fteriing  was  fold  to  various  perlbns ;  the  average  price  was 
three  pounds  fifteen  {hillings  per  oonce;  hence  eight  hundred  ounces  appear  to  have  been 
collefted  within  the  fhort  fpace  of  fix  weeks. 

The  gold  is  of  a  bright  yellow,  perfedtly  malleable  ;  the  fpecific  gravity  of  an  apparently 
clean  piece  19,000.  A  fpecimen  afiayed  here  by  iVIr.  Weaver  in  the  moid  way  produced 
from  24  grains,  22toV  E""^'"^  "^  P"''^  gold,  and  i  -j*^V  of  filver.  Some  of  the  gold  is  inti- 
mately blended  with,  and  adherent  to  quartz  ;  fome  (it  is  faid)  was  found  united  to  the  fine- 
grained iron-ftone,  but  the  major  part  was  entirely  free  from  the  matrix;  every  piece  more 
or  lefs  rounded  on  the  edges,  of  various  weights,  forms  and  fizes,  from  the  mod  minute  par- 
ticle up  to  2  oz.  17  dwt. ;  only  two  pieces  are  known  to  have  been  found  of  fupcrior  weight, 
and  one  of  thofe  is  five  and  the  other  twenty-two  ounces. 

The  bearings  are  all  taken  by  the  compafs,  without  allowing  for  the  variation. 

William  Molefworth,  Efq.  of  Dublin,  in  a  letter  to  Richard  Molcfworth,  Efq.  F.  R.  S. 
writes,  that  he  weighed  the  largeft  piece  of  gold  in  his  balance,  both  in  air  and  water,  and 
that  its  weight  was  20  oz.  2  dwt>  21  gr.  and  its  fpecific  gravity  to  that  of  fterling  gold, 
as  12  to  18.  Alfo,  that  Richard  KirWan,  Efq.  F;  R.  S.  found  the  fpecific  gravity  of  another 
fpecimen  to  be  as  13  to  i8.  Hence,  as  the  gold  was  worth  4I.  an  ounce,  Mr.  William 
Molefworth  concludes  that  the  fpecimens  are  full  of  pores  and  cavities  which  increafe  their 
bulk,  and  that  there  are  fome  extraneous  fubflances,  fuch  as  dirt  or  clay,  contained  in  thofe 
cavities. 

This  opinion  was  difcovered  to  be  well  founded,  by  cutting  through  fome  of  the  fmall 
Itimps.  '.■"'!•  '    . 

Stanefby  Alchorne,  Efq.  his  Majefty's  afTay-mafter  at  the  Tower  of  London,  affayed  two 
fpecimens  of  this  native  gold.     The  firft  appeared  to  contain  in  24  carats, 

2i|-  of  fine  gold, 
i^  of  fine  filver. 
^  of  alloy,  which  feemed  to  be  copper  tinged  witha  little  iron. 

The  feCond  fpecimen  differed  only  in  holding  21  ^  inftead  of  21  %  of  fine  gold.  ' 

Major  Johii  Brown,  of  the  royal  engineers,  tranfmitted  to  the  Right  Hon.  Thomas 
Pelham  a  fketch  of  the  fpot  where  the  gold  was  found,  which  Mr.  Pelham  permitted  to 
be  engraved  for  the  ufe  of  the  Royal  Society,  and  of  which  fig.  5.  plate  JX.  is  a  copy,  one 
ihird  of  the  fize  of  the  original. 


Gg4  yVL   Am 


tit  Pefcr'tpi'm  and  Effcn  ♦^ 

VII. 

An  Acctunt  of  the  Principles  and  EffeEl  of  Steam  Engines,  which  aB  hy  means  of  a  Tiflm, 
IVith  Defcriptions  of  the  Atmofpherical  Engine  of  NewCOMEN  and  C AW  LEY;  the  Engine 
tf  IVaTTi  which  works  in  Vacuo ;  and  a  new  Engine  ty  Mr.  SaDLEK,  in  -which  tht  direSi 
A3ion  of  Steam  and  the  Prejfurt  of  the  Attmfphere  are  tombined. 


s, 


^OME  account  of  the  original  fteatn-engme  of  the  Marquis  of  Worcefter^  and  its  fub- 
fcquent  improvements,  has  been  given  in  a  former  paper  in  this  work*.  One  of  the  chief 
imperfe£l:ions  of  that  engine  was  then  (hewn  to  confift  in  the  dircfl  aftion  of  the  ftsam,  for 
forcing,  being  neceflarily  more  than  equal  to  the  weight  of  the  column  of  water  required 
to  be  raifed ;  in  confequence  of  which,  it  became  in  moft  cafts  an  indifpenfable  condition, 
that  the  boiler  and  veffels  fhould  be  very  ftrong,  as  well  as  that  a  large  quantity  of  fuel 
fliould  be  confumed,  to  produce  fteam  fufficiently  denfc.  It  is  probable  that  thefe  inconve- 
tiiences  may  have  early  direcfted  the  thoughts  of  various  ingenious  men  to  the  application  of 
a  pifton,  though  the  difficulties  of  the  undertalcing  feem  to  have  retarded  this  purfuit  for  a 
confiderable  time.  The  firft  fteana-engine,  with  a  pifton,  made  in  1707  by  Papin  f ,  was 
little  calculated  to  remove  thefe  difficulties  ;  and  it  is  to  Newcomen  and  Cawley  that  we 
are  indebted  for  the  application  of  a  pifton  with  machinery,  by  which  the  indireft  a£tioa 
©f  fteam  little  ftronger  than  the  atmofphere,  or  rather  the  dire6t  adion  of  the  atmofphere,  is 
made  to  aft  with  fafety  and  efFeiSl-  againft  the  moft  fevere  piefTures.  It  appears  that  they  had 
brought  their  engine,  about  the  year  1713  |,  to  a  degree  of  perfection  little  different  front 
thofe  which  are  to  be  feen  at  prefent.  A  panicular  defcription  of  this  engine,  with  draw- 
ings of  its  parts,  and  a  corifiderablc  portion  of  the  hiftory  of  its  invention,  are  to  be  met  with. 
in  Defaguliers's  Courfe  of  Experimental  PhilofophVy  and  it  has  alfo  been  defcribed  in  many 
other  booics.  For  thefe  rcafojis,  I  fliall  in  this  place  give  merely  a  verbal  account  of  its 
principles  and  mode  of  operation. 

Suppofe  a  very  large  fyringe  to  be  fet  upright,  and  a  pifton  or  plug  inferted  at  the  upper 
end,  the  ufual  aperture  being  fuppofed  to  be  at  the  lower  extremity.  If  this  laft  aperture  be 
open,  riie  pifton  will  defcend  by  its  own  weight,  neglefting  the  effeft  of  friiVion  at  its  ciis- 
cumference.  But  let  it  be  imagined,  that  the  pifton  is  fupported  by  a  counter-weight  at  the 
oppofite  extremity,  by  a  lever  or  by  any  other  means.  In  this  cafe  the  pifton  will  not  defcend 
wnlefs  more  weight  be  added  to  it.  Among  the  various  ways  of  applying,  fuch  a  weight,, 
there  is  one  which  eonfifts  in  exhaufting  the  air  from  the  internal  part  of  the  cylinder 
beneath  the  pifton.  For,  if  this  were  done,  it  is  evident  that  the  whole  prefTure  of  the  atmo- 
fphere, which  amounts  to  about  twelve  pounds  on  every  circular  inch,  will  become  adiv© 
upon  the  upper  furface.  If  the  vacuum  were  to  be  produced  by  means  of  an  air-pump,  it  may 
eafily  be  allowed,  that  the  labour  of  effecting  it  would  be  at  leaft  equal  to  that  of  any  work 
Whick  might  be  performed  by  the  fijbfequent  defcent  of  the  pifton..  We  have  feen  that,  in 
Savery's  engine,  the  operation  of  fteam  is  twofold  j  namely,  by  the  direct  preffurc  from  its 

*  Philofophical  Journal,  I.  419. 
\  Loco  citato,  p.  421. 

J  Defaguliers  in  his  Leftures,  il.  467,  fays  that  it  had  been  in  ufe  near  thirty  jtm  at  the  time  he   wrote» 
Mtdthe  imprimatur  to  his  work  bears  date  November  1.7, 1743.    See  aUb  p.  531  of  the  fame  volume. 

elafticityj 


Steam  Engines  which  work  by  a  Pijon.  22$^ 

tlafticity,  and  by  the  indireft  confequence  of  its  condfenfation,  which  affords  a  vacuum. 
This  laft  is  the  only  principle  difplayed  in  Newcomen's  engine.  In  order  to  produce  the 
vacuum  at  pleafure,  it  becomes  requifite  that  various  apertures  fhould  be  formed  at  the  bot- 
tom of  the  cylinder  or  fyringe  we  have  been  fpeaicing  of: — one  to  commimicate  fteam  froni 
a  boiler  ;  another  to  admit  a  jet  of  cold  water,  to  condenfe  that  fteam  during  the  interval  in 
which  the  communication  from  the  boiler  is  cut  off;  a  third  provided  with  a  pipe  called  the 
educlion-pipe,  to  carry  off  the  condenfed  fteam  and  injeftion  water;  and  laftly,  a  fmall 
lateral  aperture  or  valve  through  which  the  permanently  elaftic  fluid,  which  cannot  de- 
fcend  through  the  edudlion-pipe,  may  be  driven  out.  This  laft  is  called  the  fnifting' 
clack.  By  thefe  provifions  the  operation  is  made  to  take  place  a'-  follows:  The  pifton 
being  up,  the  fteam-cock  is  opened,  and  fteam  iffues  from  the  boiler,  which  being  lefs 
than  half  the  weight  of  common  air,  rifes  to  the  top  and  expels  the  air  through  the 
edu£lion-pipc,  of  which  the  lower  extremity  is  covered  with  a  flap  valve  in  a  trough 
of  water.  When  the  noife  of  its  efcape  is  heard  the  fteam-cock  i$  (hut,  and  the  injeftionf 
pipe  being  opened  throws  a  ftream  of  cold  water  againft  the  bottom  of  the  pifton. 
The  fteam  becomes  immediately  condenfed,  and  the  preffure  of  the  atmofphere  fortes  the 
pifton  down  into  the  vacuum.  Upon  its  progrefs  downwards  the  injedlion  pipe  is  clofedj 
and  when  it  has  arrived  nearly  to  the  bottom  of  the  cylinder,  the  fteam-cock  is  a^ain  open- 
ed. The  elaftic  fteam  then  not  only  fills  the  fmall  fpace  between  the  cylinder  and  the  bot- 
tom, but  its  preffure  affifts  the  eduftion  water  to  pafs  off  through  its  pipe,  and  drives  the- 
difengagcd  elaftic  fluid  through  the  fnift.  In  this  ftate  therefore  the  fteam  is  foijiewhat 
ftronger  than  the  atmofphere,  and  counterpoifes  its  a£lion  on  the  upper  furface  of  the 
pifton;  whence  the  pifton  itfelf  rifes  by  the  action  of  the  counter-weight,  and  regains  Mi. 
original  pofition  at  the  top  of  the  cylinder.  A  fecond  repetition  of  the  procefs,  namely,  of 
fliutting  off  the  fteam  and  injefting  cold  water,  caufes  it  again  to  defcend,  and  in  this^ 
manner  the  alternations  may  be  continued  without  limit. 

As  the  preffure  requifite  to  wrork  an  engine  of  this  kind  with  fpeed,  and  to  overcome  the- 
friftion  of  its  parts,  may  be  eftimated  at  about  yf  pounds  for  every  round  inch,  the  effe£t 
•fa  pifton  three  feet  in  diameter,  with  ten  ftrokes  of  fix  teet  each  per  moment,  will  be  to. 
raife  a  weight  of  near  half  a  ton  at  the  rate  of  one  foot  per  iecond.  Such  a  power  will 
therefore  be  very  confiderable. 

It  is  to  be  underftood,  that  the  opening  and  ftiutting  of  the  fteam  and  injedtion  cocks 
are  performed  by  apparatus  fixed  to  the  working  beain^in  iuch  a  manner  as  to  ftrike  the 
levers  of  thofe  cocks  at  the  precife  inftants  of  time  when  their  effcfls  are  required  to  be  pro- 
duced.    The  attendant  has  no  other  office  to  perform  than  keeping  up  the  fire. 

This  curious  and  moft  eminently  ufeful  engine  became  an  objeft  of  the  refearches  of 
James  W;it',  then  of  Glafgow,  but  fince  alFociated  with  Matthew  Boulton  of  Birmingham. 
It  would  be  fuperfluous  for  me  to  enter  into  any  general  account  of  the  fcience  and  intelli» 
gence  of  either  of  tJiefe  engineers,  or  of  the  great  advantages  which  fociety  muft  ever  derive- 
when  the  fpirit  of  enterprife  is  joined  to  the  exertions  of  inenrjl  ability.  Neither  can  I  here 
attempt  to  detail  the  variety  of  new  refuks  which  are  exhibited  in  the  fpecificaiions  lodged- 
by  Watt  in  the  Chancery  offices  concerning  tnis  objtft.  My  prefent  limits  and  the  atten- 
tion which  the  world  has  already  paid  to  thefe  eminent  men^  and  the  produi^s  of  their  en- 
lightened 


130  Defcrtpthn  and  E^eEt  of  the  St  tarn  Engine  of  Watt  and  Bouiten. 

lightened  D<n:iA'ity,  render  both  unnecefiary.     I  fliall  therefore  coiitine  m|felf  to  remark,  that 
the  great  features  of  improvement  made  in  the  engine  of  Newcamen  by  W.ut  are,  firft,  that 
the  elafticity  of  the  fteam  itfelf  is  ufed  as  the  adive  power  in  his  qnginci  and  fecondly,  that  • 
tjefides  various  other  judicious  arrangements  for  the  economy  of  heat,  he  condenfes  the  ; 
fteam,  not  in  the  cylinder,  but  in  a  fcparate  veflel. 

In  the  great  cylinder  or  fyringe,  concerning  which  we  have  fpoken,  in  defcribing  the 
aigine  of  Newcomcn,  let.us  fuppofe  the  upper  part  to  be  clofed,  and  the  pifton-rod  to  Aide  ■ 
air-tight  through  a  collar  of  leathers.  In  this  fituation,  it  is  evident,  that  the  pifton  might  , 
be  deprefled  by  throwing  the  fteam  npi^n  its  upper  furface,  through  an  aperture  at  the  fuperior 
e«d  of  the  cylinder.  But  if  we  fuppofe  the  external  air  to  have  accefs  to  the  lower  furfacfi 
of  the  pifton,  we  (hall  find,  that  fleam  no  ftronger  in  its  elafticity  than  to  equal  the  weight  of 
the  atrriofphere  would  not  move  the  pifton  at  all  j  and  confcquently  that  this  new  engine 
would  require  much  denfer  fteam,  and  confume  much  more  fuel  tiian  the  old  engine.  The 
remedy  for  this  evil  is  to  maintain  a  conftant  vacuum  beneath  the  pifton.  If  fuch  a  vacuum 
were  originally  produced  by  fteam,  it  is  certain  that  its  permanency  could  not  be  depended 
Oiijunkfs  the  engine  contained  a  provifion  for  conftantly  keeping  it  up.  Mr.  Watt's  contriv- 
ance in  his  fimpleft  engine  is  as  follows  :  The  fteam  is  conveyed  from  the  boiler  to  the  upper 
part  of  the  cylinder  through  a  pipe,  which  alfo  communicates  occafionally  with  the  lower 
part,  and  beyond  that  fpace  with  a  veflel  immerfed  in  a  trough  of  water  ;  in  which  veftel  the 
condenfation  is  pe.rformed  by  an  inje6led  ftream  of  cold  water.  This  water  is  drawn  off^,  not  . 
by  an  eduflion- pipe  but  by  a  pump,  of  which  the  ftroke  is  fufficiently  capacious  to  leave 
room  for  the  elaftic  fluid,  feparated  during  the  inje(Slion,  to  follow  and  be  carried  out  with  the 
injeftion  water.  Suppofe  now  the  pifton  to  be  at  its  greateft  elevation,  and  the  communi- 
cation from  the  boiler  to  the  upper  as  well  as  to  the  lower  parts  of  the  cylinder  to  be  opened. 
The^  fteam  will  then  pafs  into  the  whole  internal  part  of  the  engine,  and  will  drive  the  air 
downwards  into  the  condenfer,  and  thence  through  the  valves  of  the  air-pump.  In  this 
fituation,  if  the  communication  from  the  boiler  to  the  lower  part  of  the  cylinder  be  ftopped, 
and  an  injection  be  made  into  the  condenfer,  a  vacuum  will  be  produced  in  that  veflel,  and 
the  fteam  contained  in  the  lower  part  of  the  cylinder  and  communication  pipe  will  expand 
itfelf  with  wonderful  rapidity  towards  the  condenfer,  fo  that  in  a  period  of  time  too  minute 
to  be  appretiated,  the  whole  of  the  fteam  beneath  the  pifton  will  be  pradically  condenfed. 
The  fteam  which  continues  to  a6t  .above  the  pifton  will  immediately  deprefs  it  into  the 
vacuum  beneath  ;  at  the  fame  time  that  by  conne<nion  with  the  external  apparatus  the 
pifton  of  the  air-pump  alfo  defcends  iu  its  barrel.  When  the  ftroke  is  nearly  com- 
pleted downwards,  the  requifite  part  of  the  apparatus  ftiuts  the  communication  with 
the  boiler ;  opens  that  between  the  upper  and  lower  parts  of  the  cylinder  and  condenfing 
veftei  ;  and  turns  the  injedion-cock.  At  this  very  inftant  the  pifton  lofes  its  tendency  to  de- 
fcend,  bccaufe  the  fteam  prefl"es  equally  on  both  furfaces,  and  continues  its  equality  of 
prefl'ure  while  the  condenfation  is  performed.  It  therefore  rifes  j  the  injedioij  is  ftopped ; 
and  the  air-pump  making  its  ftroke  fuflirs  the  injedion  water  and  a  confiderable  part  of 
the  elaftic  fluid  to  pafs  through  its  lower  valve.  The  vacuum  is  thus  kept  up  through  the 
whole. internal  capacity  of  the  engine.  As  foon  as  the  pifton  has  reached  the  upper  part  of 
itbc  cylinder,  the  communication  to  the  under  part  of  the  cylinder  is  ftopped,  and  that  with 

5  tht 


Comparifon  of  the  Steam  Engines  of  Newcomen'and  of  IVaii.  '231 

the  boiler  opened  as  before ;   the  confequence  of  which  is,  that  the  pifton  again  defcends, 
and  in  this  manner  the  alternations  repeatedly  take  place.  '  i   '' 

The  principal  augmentation  of  power  in  this  engine,  ccmipared  with  that  of  Newcomen, 
appears  to  arife  from  the  cylinder  not  being  cooled  by  the  injeiElion  water,  and  its  beinij 
practicable  to  ufe  fteam  fomewhat  ftronger  than  the  prefTure  of  the  atmofphere.  In  general 
thefe  engines  are  worked  by  fleam,  which  would  fupport  a  column  of  four  or  fivejnches  of 
mercury  befides  the  prelTure  of  the  atmofphere,  and  I  have  fometimes  feen  the  gage  as  hi»h 
as  eight  inches.  But  whether  the  comparative  profit  of  the  additional  work  was  fuch  as  to 
repay  the  extraordinary  confumption  of  fuel  in  fuch  cafes  may  be  doubted  ;  and  indeed  I  fup- 
pofe  this  praflice  is  never  adopted  but  when  the  work  of  a  manufadlory  is  fuch  as  to  eiceed 
the  power  or  rate  of  the  engine  conftrufled  for  performing  it. 

The  mofl:  ample  information  refpeiling  thefe  improvedfteam  engines,  which  rs  to  be  met 
with  in  print,  is  found  in  the  Nouvelle  Architecflure  Hydraulique  ofProny. 

When  we  contemplnte  thefe  engines  together  with  the  fimpler  engine  of  Savery,  one  of  the 
tnoft  ftriking  differences,  is,  that  the  latter  is  not  embarraffed  with  tlie  weight  and  expence 
of  the  beam  and  counterpoife.  I  believe  that  the  fly  was  firft  introduced  by  Meffrs.  Watt 
and  Boulton,  as  an  equalizer  of  the  adlion  in  fteam  engines,  which  in  various  conftru£tions 
renders  a  counterpoife  unneceflary,  but  is  faid  to  diminilh-  the  power  by  loading  the  work 
■with  friction  and  refiftance.  Of  this  however  I  can  fay  nothing  from  my  own  experience 
or  obfervation.  The  counterpoife  is  alfo  unneceflary  in  the  engines  called  doubl'e  engines,, 
in  which  the  fteam  is  made  to  a£l  alternately  on  each  fide  of  the  pifton,  by  proper  communi- 
cation from  the  boiler,  while  the  fpacc  into  which  the  pifton  is  to  move  is  made  to  com- 
municate with  the  condenfing  veflel,  where  a  conftant  injeftion  is  maintained.  I  was  alfo 
informed,  in  the  year  1794,  that  fome  engines  had  been  conftrudled  without  the  beam  ;  biit 
the  archite£l  from  whom  I  had  the  information  did  not  ftate  the  particulars. 

The  injeQion  water  and  elaftic  fluid  are  difpofed  of  in  Newcomen's  engine  with  fcarceljr 
any  lofs  of  power,  becaufe  the  former  flows  fpontaneoufly  through  the  eduftion-pipe-,  and, 
the  latter  is  driven  out  by  a  very  flight  effort  of  the  fteam  againit  the  atmofphere.     Wa'tt*s. 
engine  could  not  have  an  edudion-pipe  unlefs  the  column  were  at  leaft  34  or  35  feet  1011^,. 
to  exclude  the  atmofphere,  and  even  in  that  cafe  there  could  be  no  fnift  to  deliver  the  elaftic 
fluid.     It  was  therefore  neceflary  there  fliould  be  an  air-pump  to  carxy  off  both  >  and  this  is 
a  load  upon  the  engine  equal  to  the  amount  of  the  friction  of  thefe   additional  parts  and 
the  whole  weight  of  the  edudion  water.     I  am  not  well  informed  of  this  laft  cj^uantity;   but 
fuppofe  it  to  be  about  one  eightieth  *  part  of  the  power  of  the  engine. 

The  fteam-engine  for  which  a  patent  has  lately  been  granted  to  Mr.  Sadler,  is  worked 
without  a  lever  or  beam,  and  confequently  has  not  the  inertia  of  that  h.avy  mafs  to  over- 
come. The  greateft  part  of  its  adion  is  performed  by  the  elaftlcity  of  ftsam  ;  but  the  moft 
remarkable  character  of  his  invention  is,  that  part  of  the  fteam  previous  to  its  condenfation  is 
employed  a  fecond  time  in  another  cylinder,  the  pifton  of  which  is  fubje6l  to  the  prelfure  of 
the  atmofphere.  By  this  fecond  application  it  not  only  performs  the  ofEce  of  an  an -pump 
in  a  very  accurate  manner,  but  llkewife  adds  to  the  total  amount  of  force  in  the  uiuchuie. 

*  Suppofing  the  injeftion  water  to  be  about  -j-^ff  of  the  magnitude  of  the  cylinder  within,  aud  that, 
tjie  ftroke  would  ralfe  \  of  the  fame  magnitude  of  water  through  its  own  length. 

PlataX.. 


ajl  X  DefcriftUn  if  a  New  Steam  Engine. 

Plate  X.  exhibits  a  projedtion  of  part  of  this  engine,  the  boiler  and  the  working  parts 
being  left  out.  RSUT  reprefent  a  frame  of  wood.  A  is  the  largel-  cylinder,  of  which 
the  pifton-rod  is  kept  vertical  by  a  wheel  I,  which  runs  between  parallel  plates  with  a  very 
fmal!  degree  of  fiiake.  The  rife  and  fa'l  of  this  wheel  moves  the  arm  N  O  of  a  crank, 
which  drives  the  fly  P  Q_,  and  gives  motion  to  the  pumps  or  other  working  parts.  B  is  the 
fecond  cylinder  open  at  top,  the  pifton-rod  of  which  is  kept  vertical  in  lii<e  manner  by  a 
wheel  K.  A  connexion  is  formed  between  the  two  piftons  by  the  lever  L  M,  which  caufes 
them  to  make  their  (trokes  together.  D  is  a  valve  in  the  pifton  of  A,  which,  by  means  of  its 
tail  beneath,  is  opened  when  that  pifton  is  down,  and  continues  fo  during  the  whole  afcent, 
until  it  becomes  again  clofed  by  the  preflure  of  its  crown  againft  the  top  of  the  cylinder. 

Suppofe  the  pift:ons  to  be  near  the  tops  of  their  refpeftive  cylinders,  and  the  valve  D  to  be 
open  :  if  C  be  opened,  the  fteam  will  pafs  through  the  cylinder  A,  and  enter  B  by  the  pafTagc 
E,  driving  the  air  before  it  through  the  valve  G.  If  then  the  valve  D  be  clofed  by  raifmg 
the  pifton  or  otherwife,  and  an  injedion  of  cold  water  be  made  through  F  into  B,  the  fteam 
in  that  cylinder  and  beneath  the  pifton  of  A  will  be  condenfed,  and  both  piftons  will  de- 
fcend  ;  that  in  A  by  the  a£lion  of  the  fteam,  and  that  in  B  by  the  preffure  of  the  atmofphere. 
Near  the  termination  of  this  defccnt  the  valve  D  will  be  opened,  and  the  pifton  in  A  will  be 
left  at  liberty  to  rife,  in  confequence  of  the  equal  action  of  the  fteam  on  both  fides,  at  the  fame 
time  that,  the  valve  C  being  ftiut,  there  will  be  no  farther  fupply  from  the  boiler.  The  fteam 
■which  occupied  the  fpace  above  the  pifton  in  A  will  expand  through  E,  and  affift  the  rife  of 
the  pifton  in  B.  If  we  overlook  the  effe£l  of  refrigeration  in  the  paftage  E,  and  againft  the 
pifton  atB,  the  fteam  will  begin  to  zOl  beneath  this  pifton  with  a  force  not  greatly  different 
from  its  laft  a£lion  upon  that  in  A.  It  would  not  be  eafy  to  calculate  the  whole  effect  of 
the  fteam  in  its  fecond  application,  not  only  for  want  of  an  accurate  ftatement  of  theelafti- 
city  of  this  fluid  during  its  expanfion  ;  but  becaufe  the  pradical  effefl  of  the  temperature  of 
the  fecond  cylinder  in  diminifliing  that  force  is  ftill  more  difficult  to  be  appretiated.  I  fhall 
therefore  only  obferve,  t^hat  the  pifton  in  B  having  defcended  fo  as  to  touch  the  furface  of  the 
■injeftion  water,  and  the  elaftic  fluid  reding  upon  it,  not  only  caufes  that  air  but  a  portion  of 
the  hot  water  to  pafs  through  the  valve  W,  which  it  carries  up  and  difcharges  through  a 
conveyance  at  the  upper  part  of  the  cylinder  to  feed  the  boiler.  The  fteam  which  follows  it 
through  E,  drives  all  the  elaftic  fluid  through  the  valve  of  that  paflage,  whence  it  remains  in 
B  till  the  next  ft.roke  carries  it  off.  The  quantity  of  water  which  fhall  rife  above  the  pifton 
through  W,  may  be  regulated  by  the  height  of  the  external  furface  of  the  ciftern  into  which 
the  pipe  G  difcharges  itfelf.  The  excefs  of  the  a£lion  of  the  fteam  beneath  the  pifton  in  B, 
beyond  the  weight  of  that  pifton  and  the  water  it  carries,  will  be  an  acquifition  to  the  power 
•of  the  engine.  When  we  coarider  the  fafts,  we  may  obferve,  that,  if  B  were  too  fmalj,  the 
action  of  the  fteam  under  its  pifton  would  approach  more  nearly  to  equality  with  the  laft 
a£lion  in  A;  but  that  the  ftroke  would  be  infufBcient  to  carry  oiT  the  elaftic  fluid,  and  the 
addition  to  the  force  of  the  engine  inconfidcrable  ;  and  on  the  other  hand,  if  it  were  too  large, 
the  greateft  part  of  the  rihng  ftroke  would  be  performed  againft  the  prelFure  of  the  atmo- 
ifphere,  with  very  little  affiftance  from  the  expanded  fteam.  Whence  it  follows,  that  there  is 
a  certain  definite  proportion  under  like  circumftances  of  preffure,  temperature  and  work, 
between  the  two  cylinders,  which  will  produce  a  greater  effect  than  any  other.  To  deter- 
mine this  would  be  the  obje£l  of  computation,  if  the  data  were  at  hand-;  but  it  is  probable 
9  that 


Achromatic  Lenfes  rendereel  mire  itanfparettt,  233 

that  an  experimental  refult  with  regard  to  thofe  dimenfions  might  be  obtained  with  as  little 
trouble  as  the  mere  data  for  computation. 


VIII. 

On  thefuppofed  Improvement  of  Achromatic  Lenfes^  when  rendered  more  tranfparent  by  cementing 

than  together. 


A 


N  achromatic  glafs,  confiding  of  one  concave  and  two  convex  lenfes,  has  fix  fur- 
faci  s  at  which  the  reflexion  of  light  can  take  place.  Two  evils  of  confiderable  magnitude 
ar  produced  by  this  reflexion.  The  focal  image  becomes  obfcure  from  the  lofs  of  the 
light  fo  diverted,  and  the  ground  or  field  of  view  is  rendered  mifty  by  the  irregular  illumi- 
nation afford  d  by  part  of  this  light,  which  enters  the  tube.  Thefe  confequences  aref 
lirikingly  obferved  by  holding  an  achromatic  lens  in  fuch  a  manner  as  t6  throw  the  image 
of  a  window  upon  a  flieet  of  paper,  at  the  fame  time  that  a  like  image  is  afforded  by  a 
fimple  convex  lens  of  the  fame  focal  length.  The  latter  image  will  be  bright  and  clear,, 
while  the  former  is  very  faint.  As  the  reflexion  of  light  is  ftrongelt  at  furfaces  which  con- 
fine mediums  moft  different  in  denfity,  it  may  naturally  be  imagined  that  the  mifchievous 
efFe£l  of  the  four  furfaces,  at  which  the  lenfes  are  applied  to  each  other,  might  be  in  a. 
great  meafure  removed  by  the  interpofition  of  a  denfer  fluid  than  air.  *Many  years  ago  the 
Abbe  Rochon  made  fome  experiments  to  improve  achromatic  lenfes  by  this  invention,  and 
Mr.  Grateloup  afterwards  made  ufe  of  a  tranfp-irent  folid  for  the  fame  purpofe.  He  took  a 
very  pure  tear  of  maftic,  and  interpofeJ  a  piece  ot  fufHcient  magnitude  between  the  lenlesof  an 
achromatic  glafs.  Thefe  being  immerfed  under  water  of  which  the  temperature  Was  graduillyf 
raifed,  the  mafi-ic  at  length  became  foft,  and  by  prefTure  of  the  glalTes  was  made  to  occupy 
the  whole  of  the  two  fpaces  betv;een  the  concave  and  the  exterior  lenfes.  After  this  pro- 
cefs  the  compound  lens  was  beautifully  tranfparent ;  the  refledted  images  could  fcarcely  be 
difcerned;.  and  upon  trial  in  its  tube  the  telefcope  was- found  to  be  greatly  improved. 

My  attention  to  this  contrivance  was  excited  by  the  approbation  beftowed  upon  a  tele- 
fcope of  this  kind,  of  27  inches  long  and  aj  lines  aperture^  by  Citizen  Lalande,in  the  Con- 
jioiflance  de  Terns  for  the  fourth  year  of  the  French  Republic,  page  364.  It  appeared  to 
me,  as  it  certainly  will  to  the  reader,  to  be  a  matter-of  no  fmall  fiirprife,  that  an  improvement 

♦Count  CafKiii,  Inthe  Mtmoirs  of  the  Pafifian.  Academy  for  1787,  p.   19,  informs  us,  that  a  memoiri 
Jitr  les  moyens  deperfeHtonner  Us  lunettes  acbromaliques  par  I'iaterpqfiiwn  d'un  fiuick  eitire  Us  objcBif<)  -  by  the 
Abbe  Rochon,  was  read  before  that  Academy  in  January  1774,   and  iiilcrted  in  ihe  Rccueil  des  Memoires  de 
Mechsnique  etde  PhyfKjue,  whieh  1  have  not  feen;  and  in  a  noteon  tjiis  paflage  he   quotes  the.  Report  ofv 
the  Commiflioners  of  the  Academy,  who  exprefs  their  fatisfaftion  at  the  refult  of  their  trials  for  correfting 
great  part  of  the  dcfefti  arifing  from.- the  furfacss  of  the  gkfles  by  the  iuterpofition  of  a  fluid  between  them, . 
but  recommend  trials  with  the  telefcopes  of  aftronomers  on  celeftial  objcfts;  which  it  fliould  therefore  feein  had; 
n^  then  been  made.     The  fame  author  proceeds  to  acquaint  us,  that.Mf.  Grateloup  ufed  maftic  in  1785,  afcer-- 
w'hich  the  SieilrFutois  made  excellent  lerifds  ef  thiskiiid  ;  ahd  that 'tha  maftic' anfiveied  welf  with  compound, 
knfes,  whofeinterior  furfaces  were  only  ground  (douciei.)  but  not  pol'ilhed.     In  this  laft  experiment,  however, 
it  can  hardly  be  imag^ined  that  the  lens  would  have  (li-tiported  an  high  power-;  becaufe  the  maftic,  though  it-. 
»ight  afford  tranfparency,  muft  have  left  the  confines  of  the  mediums  as  imperfeft  as  befcre. 

Vofct  II.— August  179J5.  ILli.  «fc 


234  Expefimetlfs  iV'th  Jeht'ainattc  Lenfei  cemented  together. 

cffuch  value  ihould  never  have  been  adopted  in  this  kingdom.  As  it  is  no  where  faid  that 
lenfcs  were  conftrudled  with  a  particular  regard  to  the  deaftty  and  figure  of  the  interpofed 
maftic ;  but  there  feems  reafon  to  conclude,  that  in  every  cafe  an  achromatic  lens  of  the 
ufual  conftru£lion  was  dated  to  have  been  rendered  more  perfect  by  this  treatment, — I  thought' 
it  beft  to  overlook  the  theoretical  objeiStions,  and  confine  myfelf  in  the  firil  inftance  to  experi- 
ment and  enquiry.  .  For  this  purpofe  I  took  an  achromaticlens,  confiftingof  two  convex  lenfes 
and  one  concave,  of  which  the  radii  need  not  here  be  detailed.  "When  together  they  formed  a 
compound  lens  of  7|-  inches  focus,  with  an  aperture  of  nearly  li  inch,  which,  upon  a  rough 
trial  with  a  magnifying  power  of  30  times,  exhibited  fcarcely  any  colour.  .  Upon  filling  the 
interftices  of  this  lens  with  water,  the  focal  image  became  much  brighter;  but  the  focal 
diftance  was  diminilhed  to  fomewhat  lefs  than  fix  inches,  and  much  colour  was  produced 
with  as  low  a  magnifying  power  as  ten  times.  It  is  evident,  therefore,  that  the  lens  was 
greatly.injured  by  the  expedient  made  ufe  of  to  prevent  the  lofs  by  reflexion;  and  it  may 
eafily  be  inferred  that  a  denfer  fubftance,  fuch  as  maftic,  would  have  fhortened  its  focus  and 
difturbed  its  compenfations  in  a  ftill  greater  degree. 

".  Some  time  after  making  this  experiment,  I  applied  to  the  celebrated  Mr.  Ramfden,  to  whofe 
unequalled  ability  and  invention  the  arts  of  philofophical  obfervation  are  fo  higiily  indebted. 
I  did  not  expe£l  to  receive  any  information  tending  to  (hew  that  a  combination  of  lenfes, 
differing  in  curvature  at  the  furfaces  of  appofition  and  achromatic  in  the  air,  could  retain 
the  fame  .property  when  either  partially  or  totally  immerfed  in  another  tranfparent  medium 
of  different  refradlive  or  difperfive  power.  My  principal  object  was,  to  know  whether  the 
•French  philofophers  had  conftruded  leafes  of  fix  parts  duly  adapted  to  each  other ;  that  is  to 
fay,  confidering  the  two  portions  of  mafl:ic  as  lenfes,  and  not  merely  as  a  medium  to  prevent 
lofs  by  reflexion.  From  him  I  learned  that  the  fuppofed  improvement  had  long  fince  been 
-communicated  to  him  by  fome  gentlemen  of  the  Paris  academy,  who  affirmea  that  an 
achromatic  lens  of  Dollond's  make  had  been  much  improved  by  the  interpofition  of  mafliic 
between  its  parts,  at  the  fame  time  that  they  aflerted  in  general  terms  that  the  fame  might 
be  done  with  any  other  objedl:  glafs  of  this  kind.  He  put  a  good  objedl  glafs  into  their 
hands  for  this, purpofe.  The  experiment  was  made,  and  the  refult  proved  fimilar  to  that 
which  I  have  already  related.  The  aberrations  from  figure  as  well  as  colour  became  very 
perceptible ;— and  in  a  word  the  lens,  though  much  clearer,  had  loft  its  moft  valuable 
qualities. 

Such  is  the  refult  of  a  procefs  which  has  been  in  the  poffeffion  of  our  learned  neighbours 
for  about  four-and-twenty  years,  and  is  ftill  efteemed  by  them  ;  but  which  has  never  been 
adopted  by  our  opticians  : — a  procefs,  the  value  of  which,  it  ftiould  appear,  might  be  afcer- 
tained  in  an  inftant  by  mere  infpeftion  through  the  telefcope  in  queftion.  We  feem  as  if 
driven  to  the  fuppofition  that  fomething  might  yet  remain  unexplained.  Has  the  mifchief 
-of  this  procefs  been  overlooked  by  men  fo  acute  and  enlightened  ? — Or  has  it  happened  that 
the  interior  curvatures  of  the  lenfes,  on  which  they  operated,  were  nearly  parallel  to  each 
other  ;  ,fo  that  the  addition  of  light  (with  the  magnifying  power  commonly  ufed  with  an 
•index  telefcope)  might  be  thought  to  offer  an  advantage,  in  angular  obfervations,  more  than 
ifuflicient  tocompenfate  for  the  other  defedsi 


IX.  De. 


Jpparatusfor  the  Comhujm  of  Hydrogen^  i^t,  %^ 

IX. 

Defcrlption  of  a  very  fimple  Apparatus  for  performing  the  great  Experiment  of  producing  Water 
by-the  Combujiioa  of  Hydrogen  Gas.     Invented  by  Mr.  JOHN  CVTHB£JiTSON  *. 


A 


D  B C,  fig.  6,  plate  IX.,  reprefents  the  inftrument  {landing  in  a  velTel,  abed,  nearly 
filled  with  water. 

A  D  is  a  large  glafs  bottle,  holding  about  looo  cubic  inches  of  water,  mounted  at  the  top 
with  a  brafs  cap,  which  fcrews  oft"  at  A.  The  rifing  part  at  the  bottom  is  bored  through 
and  mounted  with  brafs,  in  which  fcrews  a  piece  reprefented  by  a  b,  fig.  7,  having  a  part; 
at  one  end  which  fits  into  the  hole,  and  the  other  end  a  fliank  with  a  fcrew  at  the  bottom. 
E  F,  fig-  6,  is  a  ftraight  bar  of  brafs ;  B  C  are  tw>>  glafs  receivers,  mounted  at  the  top  with 
trafs,  each  having  a  (hank  which  pafles  through  the  brafs  bar,  and  by  means  of  a  female 
fciew  is  fcrewed  fad  to  it :  thefe  mountings  are  perforated  perpendicularly,  and  havealfo  a 
fide  hole,  which  cor^efponds  with  a  hole  in  the  brafs  bar,  paffing  from  the  (hank  of  each  re- 
ceiver; which  hole  alfo  correfponds  with  two  holes  reprefcnted  in  fig.  7,  communicating 
with  the  infide  of  the  large  bottle.  At  L,  M,  in  the  brafs  bar,  are  two  air  cocks,  with  holea 
drilled  through  them  in  fuch  a  direction,  that  when  the  blades  of  the  cocks  (land  length- 
wife  with  the  bar  they  correfpond  with  the  holes  in  it.  FR  and  E  N  are  two  ftraight  ilat 
pieces  of  brafs ;  in  each  of  them  is  a  hole,  through  which  pafs  the  ends  of  two  fcrews,  that 
are  fcrewed  faft  into  the  fides  of  the  ve(rel  containing  the  water,  and  confine  the  bars  by 
means  of  two  female  fcrews.  O  P  is  a  long  brafs  wire,  with  a  piece  of  platina  wire  a^  the 
end  P :  this  wire  is  fixed  to  the  mounting  at  the  top  of  the  bottle,  and  is  bended  fo  that  the 
end  P  ftands  as  near  as  poffible,  but  not  to  touch  the  fmall  hole  which  pa(res  through  the  piece 
ab,  fi;^.  2. 

When  this  inftrument  is  to  be  ufed,  the  large  glafs  muft  be  firft  filled  with  oxygen  gas 
(or  common  air  when  mere,  exhibition  is  iji  tended) :  this  may  be  done  either  by  means  of  an 
air  pump,  or  by  filling  it  with  waer,    inveiting  it  and  fufFcrinj;  the  air  to  afcend.     When 
either  of  thefe  oper.itions  is  to  be  performed,  it  muft  firft  be  detached  from  the  receivers  by 
unfcrewing  the  two  femafe  fcrews  0.0^     All  the  other  parts  remain  annexed  to  it,  and  care 
Biuft  be  taken  that  the  two  air-cocks  are  fliut.     When  it  is  filled  with  the  air  required,  it  mufti 
be  fet  upon  the  receivers,  the  mountings  of  which  are  marked,  as  well  as  the  bar,  and  care 
muft  be  taken  that  they  are  not  mi'placed  :   the  whole  inftrument  muft  then  be  placed  iri^ 
the  water  velTel,  as  is  reprefented.    The  receiver  B  has  a  hole  about  the  middle.at  U    This 
receiver  muft  be  filled  with  oxygen  gas,  and  C  with  hydrogen  gas.     When  the  airs  or  gafes 
are  to  be  lighted,  eledtric  fparks  muft  be  made  to  pafs  from  the  end  of  the  platina  to  the : 
hole  in  a  continual  furceflion  ;  and  while  thefe  fparks  are  palhng,  the  cock L  muft  be  openedi 
by  degrees  till  the  air  is  feen  to  take  fire;   the  ele(ftric  fparks  muft  then  ceafe,  and  the  fize 
of  the  (lame  may  be  regulated  by  turning  the  cock  either  one  way  or  the  other.     The  otherr 
cock  muft  then  be  fet  either  quite  open,  or  partly  fo,  accordingly  as  you  find  the  flame  af.. 
fefted  by  it.     As  you  find  the  gafes  decreafe.  in  the  receivers,  fill  them  by  certain  known-, 
meafures,  and  continue  the  operation  f. 

SCIENTIFIC 
•  Communicated  by  George  Pearfon,  M.D.  F.R.S.  &c. 

f  The  above  deCcription  wasdrawn  up  by  Mr.  Cuthbertfon.     I  find,  upon  examination  of  the  apparatus  at  Dr». 
Pearfon's  houfe,  that  the  hole  throwgh  which  the  hydrogen  is  inuroduced  is  made  very  fmall,  but  that  the  otherhote  • 

Hhz.  thtoujlt, 


%^  TrteitdUgs  of  the  Natmel  IrJltluU  if  FraiKA, 

SCIENTIFIC    NEWS. 

Jccount  of  the  Public  Sitting  of  the  National  Injiiute  of  Sciences  and  Arts,  held  at  Paris  the 
l^th  Alejfulor,  in  the  Tear  VI.  (July  3,  lyyS.) 

CITIZEN  Bitaube  took  the  chair  at  half  paft  five  o'clock,  the  citizens  Villars  and  An- 
drieux  performing  the  office  of  fecretaries.  Citizen  Villars  afcended  the  tribune,  and  gave 
an  account  of  the  operations  of  the  clafs  during  the  laft  trimeflre,  of  which  the  following 
is  an  abftra^t  : 

A  memoir  of  Cit.  Camus  on  the  typograpTiic  art,  polytipage,  and  the  art  of  compofing 
■geographical  charts,  fuch  as  have  been  executed  by  the  celebrated  Haas  at  Bafle. 

A  memoir  of  Cit.  Langlee  on  the  Arabian  poets  who  preceded  Mahomet.  This  young 
and  laborious  ftudent  (hewed  that,  even  at  a  period  fo  remote,  the  greater  part  of  thefe 
writings  poflefled  confiderable  poetical  merit. 

Cit.  Monges  read  a  memoir  on  the  ruins  of  Perfepolis,  in  which  he  proves  that  the  de- 
ftrudlion  by  Alexander  was  not  total,  but  that  it  fubfifted  long  afterwards. 

Cit.  Papon,  aflbciate  correfpondent  of  the  clafs  of  moral  and  jsolitical  fcicnces,  read  to 
the  claCs  of  literature  a  memoir  on  the  advantages  which  may  be  obtained  from  the  ftudy 
of  Greek  and  Roman  infcriptions,  in  order  to  afcertain  a  variety  of  hiftorical  facls. 

Cit.  Lefevre-Gineau  gave  a  fhort  account  of  the  obje£t  of  the  various  mathematical 
tfnemoirs  which  had  been  read  during  the  lafl:  trimeflre. 

A  memoir  of  Cit.  Lamarck  concerning  the  aftion  of  the  moon  upon  the  atmofphere.  It 
lias  been  obferved,  that  when  this  fatellite  is  to  the  north  of  the  equator,  the  winds  blow, 
■ior  the  mod  part,  from  the  north  ;  and  that  they  pafs  to  the  weft  or  fouth-weft,  which  in 
thefe  climates  are  attended  with  rain,  when  the  moon  is  to  the  fouth  of  the  equator. 

Cit.  Flangaques,  aflbciate  correfpondent  at  Viviers,  tranfmitted  to  the  clafs  a  memoir  on 
ihe  refraftion  of  light. 

Cit.  Leboflut  communicated  a  memoir  on  the  integral  calculus,  which,  befides  the  pcr- 
fpicuous  difpofition  of  its  parts,  exhibits  fome  original  methods,  invented  by  the  author. 

A  memoir  of  the  laborious  and  indefatigable  Meflier,  on  the  comet  of  the  23d  Germinal, 
^April  12).  The  orbit  of  this  comet,  which,  after  having  been  feen  for  43  days,  difap- 
peared  in  the  conftellation  Urfa  Major,  has  been  calculated  according  to  the  method  of 
Laplace.  Fifty  comets  have  already  been  obferved  by  Meflier,  of  which  21  were  difcovered 
ty  him. 

Cit.  LafTus,  who  was  appointed  to  give  an  account  of  the  memoirs  on  natural  philofophy 
and  chemiftry,  mentioned  a  memoir  of  Cit.  Guy  ton  on  the  affinities  and  the  decompofitioa 
S)i  falts  at  a  temperature  beneath  the  freezing  point. 

through  which  the  oxygen  paffes  is  of  confiderable  magnitude.  I  conclude  that  thefe  dimenfions  of  the  aper- 
tures were  afcertained  by  experiment,  as  the  beft  fuited  to  the  complete  though  flow  cpmbullion  of  the  hydro- 
gen. As  the  bulk  of  hydrogen  gas  required  to  be  introduced,  for  perfeft  comb\i[lion,  it  more  than  twice  that 
of  the  oxygen,  and  the  friftion  througli  the  fmall  aperture  is  very  great,  it  becomes  neceffary  that  the  preflure 
to  extrude  the  former  fliould  be  the  ftrongeft.  The  hole  t  renders  it  impoflible  to  extrude  the  oxygen  by  the 
reaftion  of  any  longer  column  of  water,  than  from  that  hole  to  the  furface  of  the  water  in  the  tub;  but  the 
areffure  which  can  be  excned  in  tl\e  vtffcl  B  is  nearly  twice  as  much.  N. 
* .  Cit. 


Pneietiings  tf  tht  National  tnfittuU  if  Ffantiy  %«y 

Cit.  Clouet,  affbciate  correfpondent  at  Ouzour,  near  Gien,  «ranfmitted  a  mcmoijf  to  the 
clafs,  defcribing  a  method  of  converting  iron  into  fteel  witliout  cementation.  He  makes 
ufe  of  files,  alumine,  &c. 

Cit.  Baume,  likewife  aflbciate  correfpondent,  read  to  the  clafs  a  memoir  on  the  material 
of  which  artillery  is  made,  and  the  caufe  of  the  degree  of  heat  they  acquire  after  a  few  dif- 
charges.     He  offers  a  new  compofition  lefs  fufceptible  of  becoming  heated. 

Cit.  Gibert  treated  of  fleece-bearing  animals,  or  fheep,  and  the  advantages  which  com- 
merce may  derive  from  their  produce.  Lamarck  gave  an  account  of  the  cuttle  fifli  j  and 
Cit.  Cuvier,  of  the  internal  difpofition  of  the  iAroat  of  birds,  by  means  of  which  they  uttct 
founds  more  or  lefs  acute.  Cit.  Defeflarts  was  the  author  of  an  excellent  memoir  on  the 
fmall-pox,  with  a  (hort  account  of  Galvanifm. 

The  clafs  of  mathematical  and  phyfical  fclences  had  propofed  as  the  fubjeft  of  a  prize» 
to  be  determined  on  the  15th  Vendemiaire,  in  the  year  Vll,  (0£lober  6,  1798)  for  which 
the  produ6lions  of  candidates  were  to  be  received  until  the  firft  of  Germinal  laft,  (March 
21, 1798)  the  following  queftion  : 

What  are  the  ufes  of  the  liver  In  the  various  clafles  of  animals  ? 
One  memoir  only  has  been  received,  which  does  not  apply  to  the  queftion.     The  clifs 
has  therefore  thought  proper  to  divide  it,  in  order  to  facilitate  the  folution.     In  this  iox^ 
it  becomes  the  objeiSi:  of  two  prizes.     The  queftion  for  the  firft  prize  is, 

To  afcertain  the  form,  fituation,  magnitude,  comparative  weight,  texture  of  the  veflelsfc 
communications,  and  appendices  to  the  liver,  confidcred  in  the  principal  clafles  of  .animals 
from  man  to  infects,  mollufcae,  and  worms. 
The  obje£t  of  the  fecond  prize  is, 

The  analyfis  of  the  hepatic  or  cyftic  bile  in  the  feveral  clafles  of  animals  here  mentioned. 
Memoirs  will  be  received  till  the  firft  Nivofe,  in  the  year  VIII,  (December  21,  1799) 
and  the  prize  will  be  afcertained  on  the  15th  of  Germinal  following  (April  4).  The  prize 
for  each  queftion  will  be  a  medal  of  gold  weighing  one  kilogramme  (22966  grains,  or  4702* 
«7dwts.  troy).  The  Inftitute  has  pubhflied  a  program,  exhibiting  the  conditions  to  which 
candidates  muft  conform. 

A  prize  was  decreed.  It  was  divided  between  two  difl"erent  works ;  but  in  effect  it  proved 
but  one,  becaufe  the  fame  perfon  was  entitled  to  both.-  In  the  year  IV  the  clafs  of  mathe- 
matical and  phyfical  fciences  propofed  the  following  object  : 

To  conftruft  a  pocket  watch  proper  to  determine  the  longitude  at  fca,  by  obferving  fuch 
divifions  as  indicate  the  decimal  parts  of  the  day,  namely,  tenths,  thoufandths,  and  ten 
thoufandths ;  or  the  fyftem  in  which  the  day  fliall  be  divided  into  ten  hours,  the  hour  into 
one  hundred  minutes,  and  the  minute  into  one  hundred  feconds. 

The  Inftitute  divided  the  prize  between  two  watches,  No.  i,  bearing  the  epigraph  "  Ma 
*'  liberte  fait  ma  conftance ;"  and  No.  2.  having  the  Infcription  "  Au  tems  qui  inftruit." 
Cit.  Louis  Berthout  conftrudted  both  watches.    His  name  was  proclaimed  amidft  the  ap» 
plaufes  of  the  afllftants. 

The  clafs  of  moral  and  political  fclences  propofed  the  two  folbwing  queftions,  one  re- 
lative to  the  fecial  fcience,  and  the  other  to  geography  : 

What  ought  to  be  the  extent  and  the  limits  of  power  in  the  father  of  a  family  In  a  weU^ 
eonftitated  republic ,' 


338  'Ih-ocffdings  of  tbt  Nat'tcKal  Injituti  cf  t'rana. 

The  reception  of  memoirs  will  terminate  on  the  1 5th  MelTidor,  in  the  year  VII,  (July  j^ 
1799)  and  the  prize  will  be  diflributed  the  15th  Vendcmiaire,  in  the  year  VIII  (Odober  3, 
J799)- 

To  determine  the  great  changes  which  have  taken  place  in  the  globe  of  the  earth,  and 
are  either  indicated  or  proved  by  hiftoiy. 

The  concurrence  will  ceafe  on  the  <;th  Vendcmiaire,  in  the  year  VIII,  (OiElober  6j_ 
3799)  and -the  prize  will  be  diftributed  en  the  15th  NivoCe  following    (January  4,  1800). 

The  fame  clafs  had  two  prize;  to  diftribute  at  this  fitting.     One  on  the  quellion,  1.  For- 
what  objeils,  and  on  what  conditions,  is  it  proper  that  a  republican  Rate  fliould  open  a 
public  loan  ?     The  other  on  this  queftion :    2.  What  ate  the  inftitutions  moll  proper  to 
eftablifti  the  morals  of  a  people  ? 

The  inemorrs  tranfmitted  not  having  complied  with  the  condition^  of  the  program,  the 
Inflitute  propofes  again  the  quellion  refpecfling  loans  for  th«  year  Vll.  The  concurrence 
■will  clofe  on  the  7th  Meffidor  'June  25,  \'K^)),  the  piizf  will  be  given  on  the  15th  Vci> 
demiaire  following  (0£lober  6,  i  ,99)  ;  and  the  clafs  of  moral  and  political  fclences,  at  its 
next  public  lilting,  will  give  a  new  program  for  the  development  of  the  queftion  refpeft- 
Ing  inditutions.  Among  the  memoirs  which  have  been  received,  three  are  noticed  as  worthy 
of  diftinflion,  refpetlively  bearing  the  epigraphs,  i.  Si  forte  necefle  eft  . . .  hngere . . .  non 
exaudita  . . .  contingent ;  dabiturque  licentia  fumpta  prudenter.  2.  Nee  enim  ulla  res  vehe- 
mentius  rempublicam  continet,  quam  fides.  3.  On  n'honore  pas  la  vertu  ;  on  la  refpe£le. 
The  prize  propofed  for  thefe  four  queftions  will  be  a  gold  medal  of  the  weight  of  five 
tedogrammes  (U4S3  grains,  or  23  oz.  iSdwts.  troy). 

Cit.  Lacuee ,  fecretary,  in  a  fhort  account  of  the  labours  of  his  clafs,  fpoke  of  two  memoirs 
of  Cit  Delifle-Defalles,  and  another  of  Cit.  Rocderer,  all  three  concerning  the  government 
of  China.     It  cannot  be  diflembled,  that  it  will  always  be  very  difficult  in  France  to  acquire 
a  perfeft  knowledge  of  the  government  of  a  nation,  of  which  the  laws  cannot  be  Itudied  ia 
the  country  itfelf,  or  at  leaft  in  the  writings  of  that  peopie.    Depending  on  the  report  of. 
other  writers,  who  themfelves  may  sot;  have  been  pcrfedlly  Hiformed,  the  two  members 
of  the  Inftitute  have  maintained  different  opinions,  and  each  refers  to  his  authorities.     Q,\X, 
Defalks  affirms  that  this  government  is   tyrannical,  and   brings  fa£ls    in  proof  of  this . 
aflertion.    Cit.   Roederer,  from  the  ftabllity  of  the  government,  deduces  a  proof  that  its 
bafis  is  republican.     He  eftablifhes,  with  much  acutenefs,  a  difference  between  the  patrir 
archal  government,  in  which  a  fingle  chief  influences  the  whole  family,  and  the  paternal; 
government,  in  which  the  authority  is  divided  into  as  many  branches  as. there  are  married 
individuals.     He  likewife  treats  of  the  fyftem  of  t,he  Cbinefe  writing. 

Cit.  Villeterque,  affociate  correfpondent,  read  a  memoir  fomewhat  abftraded  on  the 
difference  between  experiment  and  reafoning  in  philofophy. 

Cit.  Goffelin  was  mentioned  as  the  author  of  another  memoir,  in  which  he  has  developed- 
the  geographical  fyftcm  of  Polybius.     It  is  known  that  this  expreffion  denotes  the  ideas 
which  that  hiftorian  entertained  refpedting  the  mathematical  divifions  of  the  furface  of  the 
globe,  and  the  fituations  of  places.     The  fame  flcilful  geographer  has  before  proved  that 
Jrat_Qfthe»eSj  Strabo,  and.  Ptolemy,  had  very  incorredl  notions  of  this  fcience. 

Certaki 


M 


Scientific  N'ews.-^SubierraneouS  Road  bentath  the  Thames,  239 

Certain  memoirs  of  Cit.  Bouchad,  on  the  legiflation  of  the  Romans,  and  their  numlfmatic 
hiftory,  were  mentioned  ;  and  after  theie  accounts  the  prefident  fucceflively  announced  the 
readings.     . 

Cit.  Lcfevre-Gineau  read  for  Cit.  David  Leroy  a  memoir  on  the  (hips  of  the  ancients, 
m  which  he  proves  that  we  may  derive  ufeful  in(lru£lion  from  them.  Cit..  Delambre  read  a 
memoir  on  the  meafure  of  a  bafe  talcen  in  the  neighbourhood  of  Melun,  for  determining  the 
length  of  the  meridian, 

Cit,  Fleurieu  read  a  memoir  on  the  civilization  of  the  north-weft  parts  of  America,  where 
the  traces  are  found  of  acquifitions  which  do  not  belong. to  nations  abfolutely  favage  ;  fuch 
as  ingenious  conftruftions,  fculptures  and  indifferent  paintings  reprefenting  animals,  the 
parts  of  the  human  body,  &c.  He  concludes  that  their  anceftors  fled  to  thefc  countries 
from  the  ravages  of  the  Spaniards  during  the  conqueft  of  Mexico. 

Cit.  Chaptal  read  a  memoir  on  the  yellow  colour  obtained  from  vegetables. 

Cit,  Monges  difcuffed  the  queftion,  whether  the  two  antique  ftatues  known  by  the  names 
of  the  gladiator  and  the  dying  gladiator  do  really  reprefent  gladiators,  He  clearly  efta^ 
blifhes  the  diiFerence  which  exifted  between  the  gladiators  of  the  Romans  and  the  athletics 
of  the  Greeks.  The  firft  were  barbarians,  whofe  lives  were  mercilefsly  expofed ;  the  fecond, 
Greeks,  and  fometimes  heroes,  who  diftinguifhed  themfelves  by  their  ability  in  perfonal  ac>- 
tivity.  The  author  does  not  believe  that  the  ftatues  in  queftion  are  entitled  to  the  deno- 
minations they  bear. 

■  Cit.  Colin  d'Harleville  himfelf  read  a  dialogue,  entitled,  "Man  and  his  confcience,"  a 
very  well  written  phllofophical  produ£tion.  Cit.  Lalande  read  a  piece  on  the  variation  of 
the  magnetic  pole. 

The  fitting  was  terminated  by  Cit.  Mole,  who  delivered  a  very  happy  tale  written  by  Cit.' 
Andrieux,  entitled,  The  Deaij  of  Badajoz. 


THE  public  attention  has  lately  been  much  excited  by  a  proje£l:  of  Mr.  R.  Dodd,  engineer, 
for  a  communication  between  the  counties  of  Kent  and  Effex,  by  a  tunnel  or  fubterraneous 
road  beneath  the  Thames,  from  Gravefend  to  Tilbury.  The  particulars  as  they  appear  in 
the  newfpapers,  inferted  as  I  apprehend  by  the  engineer  himfelf,  are  as  follow ; 

The  tunnel  is  to  be  cylindrical,  and  lined  on  all  fides  with  ftone  keyed  together  in  the 
manner  of  an  arch ;  the  internal  diameter  to  be  fixteen  feet,  which  Mr.  Dodd  imagines  will 
be  fufficient  for  foot,  horfe,  and  carriage  paflengers.  The  paflage  muft  of  courfe  be  illumi- 
nated with  lamps,  and  a  fteam-engine  is  propofed  to  be  erected  in  a  proper  fituation  to  draw 
off  the  drainage  water  if  any  ftiould  accumulate.  The  eftinute  is  ftated  as  follows: 
To  900  yards  (running  meafure)  of  tunneling,    including  excavations,  vaulting 

with  key-ftones,  &c.  at  12I.  per  yard  -  -  -  "    jC*  *Oj8oo 

To  relaying  the  bottom  with  new  made  ground  900  yards  at  il.  each  -  gao 

To  placing  lamps  and  lamp  irons  tlirough  the  tunnel,  colledors'  rooms,  and  gates 

at  each  end  .  .  -  «  .  j^qq 

To  making  good  the  entrance  roads  at  each  end  of  the  tunnel  -  -  160 

To  a  fteam-engine  to  draw  off  drainage  water  -  -  -  I>78o 

Neccffary  machinery  during  the  execution  -  -  -  ^00 

T»  ten  per  cent,  upon  the  whole  for  contingencies  •  5  ;  i»4tS 

■^■■"— ■-• 

9  Total  ;C-i5)95S 


i4J*  Yunnel  beneath  t^e  Thamn.—'Six  SateHties  of  the  Georgium  Stdus, 

I  do  not  find,  from  the  enquiries  I  have  yet  been  able  to  make,  that  any  effective  fteps  have 
been  taken  towards  carrying  this  plan  into  execution.  It  may,  as  Mr.  D.  obferves,  be  done 
either  at  the  expence  of  the  two  counties,  or  by  a  private  fharing  company  under  an  aft  of 
Parliament  of  the  fame  tenor  as  is  ufually  obtained  for  canals.  But  whatever  may  be  the 
mode,  there  can  be  no  doubt  of  the  very  great  commercial  advantages  of  fuch  a  communi- 
cation. It  would  demand  a  greater  degree  of  attention  and  refearch  into  the  circumftances 
of  local  fituation  ;  fuch  as  the  depth  and  pofition  of  the  main  channel,  the  elevations  of  the 
banks,  the  nature  of  the  ground,  with  the  prices  of  materials  and  workmanfliip,  than  on  the 
prefent  occaiion  can  be  thought  of,  to  form  any  judgment  of  the  eftimate  or  the  difficulties 
which  may  attend  this  important  work.  To  the  great  public,  Mr.  Dodd's  propofal  will  ap- 
pear interefting  in  a  more  general  point  of  view.  Wnen  it  is  confidered  that  the  praiTtice  of 
making  tunnels  has  now  been  known  for  a  confiderabie  number  of  years  in  this  king- 
dom ;  that  in  many,  if  not  moft  inftances,  a  tunnel  will  be  much  cheaper,  and  full  as  fafe, 
durable  and  convenient  as  a  bridge  ;  that  the  tunnel  may  be  made  (at  leaft  in  favourable  cir- 
cumftances of  the  ground)  in  fituations  where  a  bridge  would  be  impra£ticab'ie,  and  will  leave 
that  moft  valuable  defideratum  the  clear  navigation  above  unimpeded  : — this  happy  thought 
of  Mfr  Dodd  may  be  allowed  topromife  beneficial  confequences  of  the  greateft  magnitude  to 
the  community. 

Dr.  Herschel  has  difcovered  four  additional  fatellites  of  the  Georgium  Sidus.  His  paper 
on  this  obje£t  is  inlerted  in  the  late  publication  of  the  Royal  Society  *.  By  recurring  to  his- 
former  communication  on  this  fubjeift  fj  the  two  old  fatellites  are  found  to  revolve,  the  firfi; 
in  8  days  17  h.  i  m.  17  iec.  at  the  diftance  of  33'' from  its  primary,  and  the  fecondin  13  d.  11  h. 
j  m.  1,5  fee.  at  the  diftance  of  44''',23.  The  planes  of  their  orbits  form  fuch  large  angles  with 
that  of  the  planet  itfelf,  and  confequently  to  the  ecliptic,  as  to  be  almoft  perpendicular  to  it. 
-  To  this  remarkable  departure  from  the  analogy  of  the  old  planets  another  ftill  more  fingular 
is  now  announced.  They  movi  in  a  retrograde  dlreBion  !  The  new  fatellites  revolve  as  follows^ 
the  periodical  times  being  inferred  from  their  greateft  elongations :  The  interior  fatellite  in 
5.d.  21  h.  35  m.  at  the  diftance  of  25",S. — A  fatellite  intermediate  between  the  two  old 
bnes  in  lod.  23  h.  4  m.  at  the  diftance  of  38'',57. — The  neareft  exterior  fatellite  at  about 
double  the  diftance  of  the  fartheft  old  one,  and  confequently  its  periodical  time  38  d.  i  h, 
4p;m. — And  the  moft  diftant  fatellite  full  four  times  as  far  from  its  primary  as  the  old  fecond 
fatellite.  Whence  it  will  take  at  leaft  107  d.  16  h.  40  m.  to  complete  its  revolution.  Whether 
the  motions  of  thefe  four  be  direct  or  retrograde,  is,  I  fuppofe,  not  yet  determined. 

From  fome  obfervations  of  the  Do£tor,  with  an  excellent  feven  foot  teletcope,  certain  appear- 
ances refcmbling  that  of  two  rings  furrounding  the  planet,  and  croffing  each  other  at  right 
angles,  were  feen  on  feveral  different  days.  They  were  not  altered  in  pofition  by  turning  the 
fpeculum  in  its  cell ;  but  there  is  little  doubt  that  they  were  optical  deceptions,  becaufe  theV' 
kept  their  pofition  with  refpeci  to  the  tube,  after  the  relative  pofition  of  the  parallel  had  been 
much  changed  by  the  earth's  rotation,  and  becaufe  they  did  not  appear  with  larger  telefcopes 
applied  during  the  courfe  of  ten  years.  The  difk  of  the  Georgium  Sidus  is  flattened.  It  there- 
fore revolves  with  confiderabie  rapidity  on  its  axis.  From  the  very  faint  light  of  the  fatellites, 
they  are  obferved  to  difappear  in  thofe  jwirts  of  their  orbits  which  bring  them  apparently  neareft- 
the  planet.  This  does  not  arife  from  an  atmofphere  j  for  theefteCt  is- the  fame,  whether  tise; 
jbtcUite  be  withiji  or  beyond  the  planet. 

•  Phil.  Tranf.  178S,  p.  47.  f  Ibid.  178?. 


.0^ 


'^''^/if    (  (  <!//(>////<  ft/  ^u/^Wrl/^(r)% 


FhHivJoiimtJ  Yol.Il.BJX flii-inij  fi.  i4t>. 


f^  /yu'/(7l  i'f'//u    (/(•/</ ^    /////<■     ^ /)'//!/■     (    (>// It///  (•/    ///rAA'/i' 


Barhwj^llp 


(2y^ra/m^%j  n^^//f^  ^u,    /,C)_J/a^/e^  (/)^  „ 


Fhilos Journal  Vol JlJi.  X .  tarnutpi4'>. 


9B9a 


JOURNAL 

OP 

NATURAL   PHILOSOPHY,   CHEMISTRY, 

AND 

THE    ARTS. 


SEPTEMBER     1  7  Q  8. 


ARTICLE   L 

E'cperiments  tn  carlonatti  Hydrogenous  Gas  ;  nvith  a  Fieiu  to  determine  whether  Carhon  he  * 
ftmpk  or  a  compound  Subjance  *.     By  Mr.  Willi  AM  Henrt. 

X  H  E  .progrefs  of  chemical  fciencc  dcperfds  not  only  on  the  acqulfition  of  new  fadls,  but 
on  the  accurate  eflablifhment,  and  jufl  valuation,  of  thofe  we  already  poflefs  c  for  its  general 
principles  will  otherwife  be  liable  to  frequent  fubverfions ;  and  the  mutability  of  its  do£lrines 
will  but  ill  accord  with  the  unvaried  order  of  nature.     Imprefled  with  this  conviftion,  I 
have  been  induced  to  examine  a  late  attempt  to  withdraw  from  its  rank  among  the  element- 
ary bodies,  one  of  the  moft  intcrefting  objedls  of  chemiftry.     The  inferences  refpe6ling  the 
compofition  of  charcoal,  deduced  by  Dr.  Auftin  from  his  experiments  on  the  heavy  inflam* 
inablef  air  f,  lead  to  changes  fo  numerous  in  our  explanations  of  natural  phenomena,  that 
they  ought  not  to  be  admitted  without  the  ftrideft  fcrutiny  of  the  reafoning  of  this  philofo- 
pher,  and  an  attentive  repetition  of  the  experiments  themfelvcs.     In  the  former,  fources  of 
fallacy  may,  I  think,  be  cafiJy  deteded ;  and  in  the  latter  there  is  reafon  to  fufped  that  Dr. 
Auftin  has  been  mifled  by  inattention  to  fome  collateral  circumftances.     Several  chemifts, 
however,  of  dillinguiflied  rank  have  expreffed  themfelves  fatisficd  with  the  evidence  thus 
produced  in  favour  of  the  compofition  of  charcoal ;  and  amongft  thefe  it  may  be  fufEcienC 
to  mention  Dr.  Beddoes,  who  has  availed  himfelf  of  the  theory  of  Dr.  Auftin  in  explaining 
fome  appearances  that  attend  the  converfion  of  caft  into  malleable  iron  \. 

The  heavy  inflammable  air,  having  been  proved  to  confift  of  a  folution  of  pure  charcoal 

•  From  the  Plwl,  Tranf.  J797.  t  Phil.  Tranf.  vol.  Ixxx.  p.  51. 

%  Phil.  Tranf.  vol.  Ixxxi. 

Vox.  II.— Sept.  1798.  li  in 


842  Experiments  en  carltiiatcd  Hydrogen  Gas, 

in  light  inflammable  air,  is  termed  in  the  new  nomenclature,  carbonated  hydrogenou-s  gas. 
By  repeatedly  pafling  the  electric  (hock  through  a  fmall  quantity  of  this  gas,  confined  in  » 
bent  tube  over  mercury,  Dr.  Auftin  found  that  it  was  permanently  dilated  to  more  thaa 
twice  its  original  volume.  An  cxpaafion  fo  remarkable  could  not,  as  he  obferves,  be  oc- 
tafioned  by  any  other  known  caufe  than  the  evolution  of  light  inflammable  air. 

When  the  eloSlrified  air  was  fired  with  oxygenous  gas,  it  was  found  that  more  oxygen 
was  required  for  its  faturation  than  before  the  action  of  the  eledlric  fluid  ;  which  proves  that 
by  this  procefs  an  actual  addition  was  made  of  combuftible  matter. 

The  light  inflammable  air-difengaged  by  the  eledrization  proceeded  without  doubt  from 
the  decompofition  of  fome  fubftance  within  the  influence  of  the  eleftric  fluid,  and  net  mere- 
ly from  the  expanfion  of  that  contained  in  the  carbonated  hydrogenous  gas  :  for,  had  the 
quantity  of  hydrogen  remained  unaltered,  and  its  ftate  of  dilatation  only  beeachanged,  there 
would  not,  after  electrization,  have  been  anyincreafed  confumption  of  oxygen. 

The  only  fubftances  in  contad  with  the  glafs  tube  and  mercury,  in  thefe  experiments,  be- 
fides  the  hydrogen  of  the  denfe  inflammable  gas,  were  carbon  and  water  j  which  laft,  though 
probably  not  a  conftitueat  of  gafes,  is  however  copioufly  dilFufed  through  them.  If  the. 
evolved  hydrogen  proceeded  from  the  decompoHtion  of  the  former  of  thefe  two  fubftances,, 
it  is  evident  that  a  certain  volume  of  the  carbonated  hydrogenous  gas  muft  yield,  after 
electrization,  on  combuftion  with  oxygen,  lefs  carbonic  acid  than  an  equal  volume  of 
non-eleftrified  gas  ;  or,  in  other  words,  the  inflammation  of  2o  meafures  of  carbonated  hy- 
drogen expanded  by  eleCtricity  from  10,  {h9uld  no»  afford  fo  much  carbonic  acid  as  lo 
tncafures  of  the  uneleCtrified.. 

Frora'the  fa£t  which  has  been  before  ffated,  refpe£ting  the  increafed'  confumption  ofi 
exygen  by  the  electrified  air,  it  follows,  that  in  determining  the  quantity  of  its  carbon  by 
combuftion,  fuch  an  addition  of  oxygen  fliould  be  made,,  to  that  necefTary  for  the  faturation 
«f  the  gas  before  expofure  to  the  cleClric  {hock,,  as  will  completely  faturate  the  evolved 
hydrogen.  For,  if  this  caution  be  not  obferved,  we  may  reafonably  fufpeCt  that  the  product 
of  carbonic  acid  is  diminiflied,  only  becaufe  a  part  of  the  heavy  inflammable  air  has  efcaped 
combuftion.  It  might  indeed  be  fuppofed,  that  in  confequence  of  the  fuperior  affinity  of 
carbon  for  oxygen,  the  whok  of  the  former  fubftance  contained  in  the  denfe  inflammable 
gas  would  be  faturated  and  changed  into  carbonic  acid,  before  the  attraction  of  hydrogen  for 
oxygen  could  operate  in.  the  production  of  water.  But  I  have  found  that  the  refidue,  after 
inflaming  the  carbonated  hydrogenous  gas  with  a  deficiency  of  oxygen,  and  removing  the.- 
carbonic  acid,,  is  notfimply  hydrogenous,  but  carbonated  hydrogenous  gas. 

In  the  2d,  sth  and  6th  of  Dr.  Auftin's  experiments,  in  which  the  quantity  of  carbon  in 
the  electrified  gas  was  examined  by  deflagrating  it  with  oxygen,  the  combuftion  was  in*, 
complete  becaufe  a  fuflicicncy  of  oxygen  was  not  employed  ;  and  Dr.  Auftin  himfelf  was- 
aware  that  in  each  of  them  "  a  fmall  quantity  of  heavy  inflammable  air  might  efcape  un- 
altered." It  is  obf<  rvable  alfo,,  that  the  produCt  of  carbonic  acid  from  the  eleCtnfied  gas  in- 
creafed in  proportion,  as  the  combuftion  was  more  perfeCt  We  may  infer,  therefore,  that  if 
it  had  been  complete  there  would  have  been  no  deficiency  of  this  acid  gas,,  and  confequent- 
ly  no  indication  of  a  decompofition  of  charcoal.  A  ftrong  objection,  however,  is  applicable- 
to  thefe  as  well  as  to  moft  of  Dr.  Auftin's  experiments,  that  the  refidues  were  not  examined 
vith  fufficient  attention.    In  one  inftance,  we  arc  told^  that  the  remaining  gas  was  inflam-. 

mable, 


Expifimntts  »H  carbonated  Hydrogen  Gas,  243 

maWe,  and  in  another  that  it  fupported  combuftion  like  vital  air.  I  need  hardly  remark, 
that  a  fatisfaftory  analyfis  cannot  be  attained  of  any  fubftance,  without  the  moft  fcrupulous 
regard  not  only  to  the  qualities,  but  to  the  precife  quantities  of  the  produdls  of  our  opera- 
tions. 

To  the  8th  and  9th  experiments  the  objeftion  may  be  urged  with  additional  weight, 
which  has  been  brought  againft  the  preceding  ones,  that  the  quantity  of  oxygen,  inftead  of 
being  duly  increafed  in  the  combuftion  of  the  eledtrified  gas,  was  on  the  contrary  diminifli* 
ed.  Thus,  in  the  8th  experiment  2,83  meafures  of  carbonated  hydrogen  were  inflamed  with 
4,58  meafures  of  oxygenous  gas  ;  but  in  the  pth,  though  the  2,83  meafures  were  dilated  to 
|,i6,  and  had  therefore  received  a  confiderable  addition  of  combuftibie  matter,  the  oxygen 
employed  was  only  4,09.  To  the  reft  of  Dr.  Auftin's  experiments,  cither  one  or  both  of  the 
above  objections  are  applicable. 

The  firft  and  moft  important  ftep,  therefore,  in  the  repetition  of  thefe  experiments,  is  to  de- 
termine whether  the  carbonated  hydrogenous  gas  really  fuftains  by  the  procefs  of  ele£lrization' 
a  diminution  of  its  quantity  of  carbon;  becaufe,  fhould  this  be  decided  in  the  negative,  we 
derive  from  the  fa*Sl-  a  very  ufeful  direftion  in  afcertaining  the  true  fource  of  the  evolved 
hydrogen.  The  following  experiments  were  therefore  made  with  a  view  to  decide  this 
queftion,  and  the  error  of  Dr.  Auftin  in  employing  too  little  oxygen  was  carefull/ 
avoided  *, 

Experiment  1.  In  a  bent  tube  ftanding  inverted  over  mercury,  94,5  meafures  of  carbo- 
nated hydrogenous  gas  from  acetite  of  pot-afti  were  tnixed  with  107,5  of  oxygen.  The 
total,  202,  was  reduced  by  an  explofion  to  128,5,  ^"''  ^^'^^  further  contradled  by  lime  water 
1054.     A  folution  of  hepar  fulphuris  left  only  23  meafures. 

The  diminution  by  lime  water,  viz.  74,5  meafures,  makes  known  to  us  the  quantity  of 
carbonic  acid  afforded  by  the  combuftion  of  94,5  meafures  of  carbonated  hydrogenous  gas. 
And  the  refidue  after  the  a£lion  of  hepar  fulphuris,  viz.  23  meafures,  gives  the  proportion  of 
azotic  gas  contained  in  the  carbonated  hydrogen ;  for  the  oxygenous  gas  employed,  which 
was  procured  from  oxygenated  muriate  of  pot-afli,  was  fo  pure,  that  the  fmall  quantity  ufed 
in  this  experiment  could  not  contain  a  meafurable  portion  of  azotic  gas. 

Experiment  2.  The  fame  quantity  of  carbonated  hydrogen  was  expanded  by  repeated 
eleilrical  fliocks  to  188  meafures.  The  addition  of  hydrogenous  gas  therefore  amounted  to 
93,5.  The  gas  thus  dilated  was  fired  at  different  times  with  392,5  meafures  of  oxygenous 
gas  ;  and  the  refidue  after  thefe  feveral  explofions  was  203  meafures.  Lime  water  reduced 
it  to  128,5,  ^"^  fulphure  of  pot-afli  to  19,5.  In  this  inftance,  as  in  the  former  one,  the 
produdl  of  carbonic  acid  is  74,5  meafures. 

''  The  apparatus  employed  in  thefe  experiments  was  the  ingenious  contrivance  of  Mr.  Cavendifli,  and  is 
defcribed  in  the  Ixxvth  vol.  of  the  Philofophical  Tranfaftions.  In  dilating;  the  gas,  I  fometimes  ufcd  a 
ftraight  tube,  furnilhed  with  a  cenduflor  in  the  manner  of  Dr.  Prieftley  (fee  his  Experiments  on  At,  vol.  i. 
plate  I.  fig.  16.)  The  bulk  of  the  gafes  introduced,  and  their  volume  after  the  various  e.xperiments,  were 
afccrtained  by  a  moveable  fcale,  and  by  afterwards  weighing  the  mercury  which  filled  the  tube  to  the  marks 
on  the  fcale;  by  which  means  I  was  fparcd  the  trouble  of  graduating  the  fyphons.  Each  grain  of  mercury 
Indicates  one  meafure  of  gas  ;  and  though  the  fmallnefs  of  the  quantities  fubmitted  to  experiment  may  be  ob- 
jefted  to,  yet  this  advantage  was  gained,  that  the  elcftrified  gas  could  be  fired  at  one  explofion,  as  was  done  iii 
t!ie  4th,  6th  and  Sth  experiments.  Errors  from  variations  of  temperature  and  atmofpherical  prelTure  were 
carefully  avoided. 

I  i  2  Finding 


244  EnpirtmviU  m  carhnaUd  Hydrogen  Gati 

Fining  from  the  firfl  experiment  and  other  funilar  ones,  that  the  carbonated  hydrogenous 
gas  which  was  the  fubjefl  of  them  contained  a  very  large  niixture  of  azotic  gas,  I  a^'airj 
fubmitted  to  diftillation  a  quantity  of  the  acetite  of  pot-afh,  with  every  precaution  to  prevent 
the  adulteration  of  the  product  with  atmofpherical  air.  Such  an  adulteration,  1  have  obft-rved, 
impedes  confiderably  the  dilatation  of  the  gas,  and  for  a  time  even  entirely  prevents  it. 
This  explaiiis  the  failure,  which  fome  experienced  chemifts  have  met  with  in  their  attempts 
to  expand  the  carbonated  hydrogenous  gas  by  ele£lricity.  Gas  which  is  thus  vitiated  be-. 
comes,  however,  capable  of  expanfion  after  expofure  to  the  fulphure  of  pot-afh. 

Experiment  3.  Carbonated  hydrogen  340  meafures  were  exploded  with  the  proper  pro- 
portion of  oxygenous  gas.  The  carbonic  acid  produced  amounted  to  380  meafures,  and  the 
refidue  of  azotic  gas  was  20  meafures. 

Experiment  4.  The  fame  quantity,  when  expanded  to  690*  gave  on  eombuflion  380  mea« 
fiires  of  carbonic  acid,  and  19,8  of  azotic  gas. 

Experiment  5.  Three  hundred  and  fifteen  meafures  of  carbonated  hydrogen  yielded  35a 
Hieafures  of  carbonic  acid,  and  18,5  meafures  of  azote. 

Experiment  6,  The  fame  quantity,,  after  expanfion  to  6cOj  afforded  the  fame  produfls  of 
carbonic  acid  and  azotic  gafes. 

Experiments  7  and  8.  As  much  carbonic  acid  was  obtained  by  the  eombuflion  of  408 
meafures  of  carbonated  hydrogenous  gas,  expanded  from  200,  as  from  200  meafures  of  the 
non-eleftric  fired  gas  ;  and  the  refidue  of  azotic  gas  was  the  fame  in  both  cafes. 

It  is  unneceflary  to  flate  the  particula,rsof  fevcral  other  experiments  fimilar  to  thofe  above 
related,  which  were  attended  with  the  fame  refults.  They  fufEciently  prove  tbatr  the  adlion 
of  the  eleflric  fpark,  whenpafTcd  through  carbonated  hydrogenous  gas,  is  not  exerted  in  the 
decompofition  of  carbon ;  for  the  fame  quantity  of  this  fubftance  is  found  after  as  before 
eledtrization.  Even  granting  that  charcoal  is  a  compound,  the  conftituents  of  which  are 
held  together  by  a  very  forcible  affinity,^  it  does  not  appear  likely  that  the  agency  of  the 
de6lric  {hock>  which  feems  in  this  inflance  analogous  to  that  of  caloric,  fhould  cScSi  its 
decompofition  under  the  circumflances  of  thefc  experiments.  For  it  is  a  known  property 
of  charcoal  to- decompofe  water,  when  aided  by  a  high,  temperature ;  and  its  union  with 
oxygen  is  a  much  more  probable  event  when  this  body  is  prefsnt,  than  a  feparation  into  its 
conftituent  principles.  As  an^argument  alfo  that  water  is  the  fource  of  the  light  inflam- 
mable air  in  this  procefs,  it  may  be  obferved  that  the  dilatation  in  Dr.  Auflin's  experiments 
could  never  be  carried  much  farther  than  twice  the  original  bulk  of  the  gas  *.  This  fail 
evidently  implies  that  the  expanfion  ceafed  only  in  confequence  of  the  entire  deflruilion  of 
the  matter  whofe  decompofition  afforded  the  light  inflammable  air;. and  this  fubftance  could 
not  be  carbon,  becaufe  Dr.  Auftin  admits  that  a  large  portion,  and  I  have  fliewn  that  the 
whole  of  it,  flill  remains  unaltered. 

If  the  dilatation  of  the  carbonated  hydrogenous  gas  arofe  from  the  decompofition  of  water, 
the  efleii  fhould  ceafe  when   this  fluid  is  previoufly  abftracted.     To  afcertain  whether - 

•  "  After  the  inflammable  air  has  been  e.Npanded  to  about  double  its  original  bulk,"  fays  Dr  Auttin, 
*'  I  do  not  find  that  it  increafes  further  by  continuing  the  fliocks.  Conceiving  that  the  progrefs  of  the  decom- 
"pofition  was  impeded  by  the  mixture  of  the  other  airs  with  the  heavy  inflammable,  I  palTed  the  (pjrk 
"through  a  mixturf  of  the  heavy  inflammable  air  and  light  inflammable  -,  but  the  expanfion  fucceeded  nearly 
<*'»  well  ai  when  the  heavy  inflammable  wa*  eledlrifiud  alone."    Phil,  Tranf.  vol,  Uxx.  p.  j*. 

this 


Experiments  on  carhnated  Hydrogen  Gat,     ■  jxc 

this  confequence  would  really  follow,  I  expofed  a  portion  of  the  gas  for  feveral  days  before 
electrization  to  dry  cauftic  alkali.  On  attempting  its  expanfion,  1  found  that  it  could 
not  be  carried  beyond  one  fixth  the  original  bulk  of  the  gas.  By  160  very  ftrong  ex- 
plofions  it  attained  this  fmall  degree  of  dilatation,  but  80  more  produced  not  the  leaft 
e&eSt;  though  the  former  number  would  have  been  amply  fufficient  to  have  dilated  the  gas 
in  its  ordinary  ftatc  to  more  than  twice  its  original  volume.  A  drop  or  two  of  water  being 
admitted  to  this  portion  of  gas,  the  expanfion  went  on  as  ufual ;  and  I  may  here  obferve,  that 
when  a  little  water  gained  admiflion  into  the  tube  along  with  the  gas,  in  any  experiment, 
which  often  happened  before  I  had  acquired  fufficient  expertnefs  in  transferring  the  air  from 
Water  to  mercury,  the  dilatation  went  on  with  remarkable  rapidity. 

Carbonic  acid  gas,  according  to  the  difcovery  of  M  Monge  *,  undergoes,  when  fubmitted 
to  the  eleflric  (hock,  a  change  fimilar  to  that  efFeded  on  the  carbonated  hydrogen;  and  the 
expanfion  has  been  fhewn  by  MefTieurs  Landriani,  and  Van  Marum  f,  to  be  owuig  to  ihe 
fame  caufe,  viz.  the  extrication  of  light  inflammable  air.  The  added  gas,  M.  Montre  ably 
contends, cannot  proceed  from  any  other  fourne  than  the  water  held  aifolutionby  all  aenform 
bodies,  the  oxygen  of  which  he  fuppofes  to  combine  with  the  mercury.  That  the  decom- 
ponent  of  the  water,  however,  in  the  experiments  which  I  have  defcribed,  Is  not  a  metallic 
body,  will  appear  highly  probable,  when  we  reflect  that  there  is  prefent  in  them  a  combuftible 
fiibftance,  viz.  charcoal,  which  attrafls  oxygen  much  more  ftrongly  than  metals ;  and  the 
following  experiments  evince,  that  the  mercury  by  which-  the  air  was  confined  had  no  fliarc 
in  producing  the  phenomena. 

Experiment  C).  A  portion  of  carbonated  hydrogenous  gas  was  introduced  into  a  glafs  tube 
clofed  atone  end,  into  which  a  piece  of  gold  wire  was  infertedj  that  proje£led  both  within 
and  without  the  cavity  of  the  tube.  The  open  end  of  the  tube  was  then  clofed  by  a  flopper 
perforated  alio  with  gold  wire,  fo  that  eled^rlc  fhocks  could  be  paiTed  through  the  confined 
air  without  the  contaft  of  any  metal  that  has  the  power  of  decompofing  water.  On  open- 
ing the  tube  with  its  mouth  downwards  under  water,  a  quantity  of  air  immediately  rulhed 
out. 

Experimfht  10.  The  dilatation  of  the  gas  was  found  to  proceed  very  rapidly  when  (land- 
ing oVer  water,  and  expofed  to  the  aftion  of  the  ele£tric  fluid,  conveyed  by  gold  con- 
dudlors. 

We  have  only,  therefore,  in  the  two  preceding  experiments,  one  fubftance  in  contaft  with, 
the  gas  whici  is  capable  of  decompofing  water,  viz.  charcoal.  The  union  of  this  hody 
with  the  oxygen  of  the  water  would  be  rendered  palpable  by  the  formation  of  carbonic 
aci  ;  but  Dr.  Auftin  did  not  obferve  that  any  precipitation  was  occafionedin  lime  water  by 
agitating  it  with  the  eledlrified  gas.  On  palling  up  fyrup  of  violets  to  the  eiedrrified  air, 
with  the  expedtation  of  its  indicating  the  volatile  alkali,  as  in  the  experiments  of  Dr.  Aultin, 
no  change  of  colour  took  place,  though  the  teft  was  of  unexcepcionable  purity.  On  exa- 
minmg,  however,  whether  any  alteration  of  bulk  had  been  produced  in  the  air  by  the  con- 
tact of  this  liquid,  it  appeared  that  of  709  meafureS' 100  had  been  abforbed.  SufptCting 
that  the  abforption  was  owing  to' the^prefence  of  i;arbonic  acid,  t  introduced  fonie  ILmc- 
water  to  a  volume  of  the  expanded  gas,  amounting  to  5^6  meafu/es,  when  they  were  im-- 
mediately  reduced  to  512.     The  contra'dlion  would  probably  have  been  ftill  ludre  remark- 

•  Journal  de  Phyfique,  xxix.  177.  f  Annales  de  Chimie,  iU  473. 

able. 


246  -  Expert mtHis  m  carlanatetH  Ujdrogtn  Gat. 

able,  if  the  gas  had  been  farther  expanded  before  the  admifRon  of  the  liquid.  The  change  itt 
the  lime  water  was  very  trifling  \  but  my  friend  Mr.  Rupp,  who  witnefTcd  this  as  well  as 
feveral  of  the  other  experiments,  and  who  is  much  converfant  in  the  obfervation  of  chemical 
facls,  was  fatisfied  that  after  a  while  he  faw  fmall  flocculi  of  a  precipitate  on  the  furface  of 
the  mercury.  This  contra£lion  of  bulk  cannot  be  afcribed  to  any  other  caufe  than  the  ab- 
forption  of  carbonic  acid ;  for,  befides  the  fa£l,  that  the  colour  of  fyrup  of  violets  and  of 
turmeric,  which  I  aifo  tried,  were  not  affeited  by  expofure  to  the  electrified  gas,  I  have  this' 
obje£lion  to  the  abforbed  gas  being  ammoniac,  that  no  diminution  either  of  bulk  or  tranf- 
parency  occurred  on  the  admixture  of  muriatic  acid  gas  with  the  eleGrifled  air;  whereas 
ammoniac  would  have  been  exhibited  under  the  form  of  a  neutral  fait.  When  water  was 
pafied  up  to  this  mixture  of  the  two  gafes,  there  was  an  abforption  not  only  of  the  muriatic 
gas  but  of  fomething  more. 

Conceiving  that  the  demolition  of  charcoal,  by  the  a£lion  of  the  eleftric  fluid,  was  fuffi- 
ciently  proved  by  his  experiments,  Dr.  Auftin  afllgns  the  evolved  hydrogen  as  one  of  its 
conrtitueius,  and  the  other  he  concludes  to  be  azote.  This  inference,  however,  refts  almoft 
entirely  upon  eftimates  in  which  material  errors  may  be  difcovered.  Some  of  thefe  it  may 
be  well  to  point  out  for  the  fatisfadtion  of  fuch  as  have  acquiefced  in  Dr.  Auftin's  opinion. 

The  carbonated  hydrogenous  gas  fubmitted  to  Dr.  Auftin's  experiments,  clearly  appears 
from  his  own  account  to  have  been  largely  adulterated  with  azotic  gas.  One  fource  of  its 
impurity  he  has  difclofed,  by  informing  us  that  the  gas  "  had  been  very  long  expofed  to 
water*  ;"  for  Dr.  Higgins  has  fomewhere  fhewn,  that  the  heavy  inflammable  air,  after  land- 
ing long  over  water,  leaves  a  larger  refidue  of  azote,  on  combuftion,  than  when  recently  pre- 
pared f .  It  is  probable  alfo,  that  the  proportion  of  azote  derived  from  the  water  would  in- 
creafe  with  the  time  of  its  expofure ;  and  thus  a  fertile  fource  of  error  is  fuggefted,  which 
appears  wholly  to  have  efcaped  Dr.  Auftin's  attention.  In  repeating  his  experiments,  I  was 
careful  that  comparative  ones,  on  two  equal  quantities  of  the  electrified  and  uneledtrified  gas, 
{hould  be  made  without  the  intervention  of  any  time  that  could  vary  the  proportion  of  azote 
in  either  of  the  gafes. 

To  the  9th  experiment,  in  which  the  quantity  of  azote  feems  to  have  been  increafed  to 
eleflrization,  I  muft  repeat  the  objection,  that  a  fufiiciency  of  oxygenous  gas  was  not  ufed  iij 
the  combuftion.  In  the  8th  experiment,  2,83  meafures  of  the  uneledtrified  air  were  fired  with 
4,17  oxygenous  gas,  and  only  0,15  of  the  latter  remained  above  what  was  fufficient  for  fatura- 
tion ;  but  in  the  9th,  though  the  2,83  meafures  were  expanded  to  5,16,  the  quantity  of 
oxygen  employed  was  0,08  lefs  than  in  the  former  experiment ;  and  it  may  therefore  be 
prefumed,  that  a  fmall  quantity  of  inflammable  air  might  efcape  unaltered,  and  might  add 
apparently  to  the  product  of  azote.  In  the  8th  experiment,  alfo,  the  portion  of  oxygenous 
gas  that  was  more  than  fufficient  to  faturate  the  carbonated  hydrogen,  would  probably  com- 
bine in  part  with  the  remaining  azote,  as  in  the  experiments  of  Dr.  Higgins  J  and  Dr. 
Prieftley  §.    But  in  the  ytb,  the  quantity  of  oxygenous  gas  was  hardly  fufficient  to  faturate 

•  Phil.  Tranf.  Ixxx.  54. 

>{■  Similar  fafls  refpefting  the  deterioration  of  other  gafes  by  (landing  over  water  may  be  feen  in  Dr. 
Prieftlcy's  Experiments  on  Air,  vol.  i.  p.  59.  158.  I  found  that  oxygenous  gas  from  oxygenated  muriate  of 
pot-alh  acquired  by  expofure  a  few  weeks  to  water,  ,125  its  bulk  of  azotic  gas. 

J  Experiments  and  Obfervations  on  Acetous  Add,  fcc.  p.  295. 

§  Phil.  Tranf.  Ixxix.  7, 

6  both 


e. 


Experiments  on  carionated  Hydrogen  Gas.  247 

both  kinds  of  inflammable  air  after  elcftrization,  and  could  not  therefore  diminifli  the 
azotic  gas.     When  the  proportion  of  oxygen  is  duly  increafed,  and  the  inflammation  of  the 

ledtrified  air  is  performed  in  fmall  portions,  there  is  no  augmentation,  but  on  the  contrary  a 
decreafe  of  the  quantity  of  the  azote,  as  will  appear  on  comparing  the  ift  and  2d  of  the  ex- 
periments which  I  have  related. 

Two  circumftances  were  obferved  in  the  experiments  of  Dr.  Auftin,  which  have  not  been 
noticed  in  the  preceding  account  of  the  repetition  of  them,  viz.  the  appearance  of  a  depofit 
from  the  carbonated  hydrogenous  gas  during  its  eIe£lrization,  and  the  formation  of  am- 
rnoniac  by  the  fame  procefs.  In  fome  experiments  which  I  made  on  the  firft  portion  of  gas, 
both  thefe  fads  were  fufficiently  apparent;  but  neither  of  them  occurred  on  eleflrifying  the 
gas  which  was  afterwards  procured.  Sufpe£^ing  that  the  cefTation  of  them  arofe  from  the 
fuperior  purity  of  the  latter  portion  from  azotic  gas,  1  pafled  the  eleftric  fliock  through  a 
mixture  of  carbonated  hydrogen,  with  about  one  fourth  of  its  bulk  of  azote,  and  thus  again 
produced  the  precipitate,  which  would  have  been  of  a  white  colour,  if  it  had  not  been 
obfcured  by  minute  globules  of  mercury,  that  were  driven  upwards  by  the  force  of  the  ex- 
plofion.  An  infufion  of  violets  was  tinged  green,  when  admitted  to  the  eleitrified  gas ;  but 
the  change  of  colour  did  not  occur  inftantly,  as  happens  from  the  abforption  of  animoniacal 
gas  ;  and  required  for  its  produ£tion,  that  the  liquid  fhould  be  brougnt  extenfively  into  con- 
ta6l  with  the  inner  furface  of  the  tube.  From  this  efFeit  on  a  blue  vegetable  colour,  we 
may  infer  that  the  precipitate  was  an  alkaline  fubftance,  and  probably  the  carbonate  of  am- 
moniar: ;  but  the  quantity  was  much  too  minute  to  be  the  fubjedt  of  a  more  decifive  experi- 
ment. 

I  fhall  conclude  this  memoir  with  a  brief  fummary  of  the  fa£l:s  that  are  eftablifhed  by  the 
preceding  experiments  *.  Thofe  included  under  the  firfl  head  are  deducible  from  the  experi- 
ments of  Dr.  Auftin. 

1.  Carbonated  hydrogenous  gas,  in  its  ordinary  ftate,  is  permanently  dilated  by  the  efet^rie 
fhock  to  more  than  twice  its  original  volume ;  and  as  light  inflammable  air  is  the  only  fub- 
ftance  we  are  acquainted  with,  that  is  capable  of  occafioning  fo  great  an  expanfion,  and  of 
exhibiting  the  phenomena  that  appear  on  firing  the  eledtrified  gas  with  oxygen,  we  may 
afcribe  the  dilatation  to  the  produ(Eiiin  of  hydrogenous  gas. 

2.  The  hydrogenous  gas,  evolved  by  this  procefs,  does  not  arife  from  the  decompofition  of 
charcoal ;  becaufe  the  fame  quantity  of  that  fubftance  is  contained  in  the  gas  after  as  before 
eleiSlrization. 

3.  The  hydrogenous  gas  proceeds  from  decompofed  water;  becaufe,  when  this  fluid  i-s  ab- 
fl:ra£led  as  far  as  poflTible  from  the  carbonated  hydrogenous  gas,  before  fubmitting  it  to  the 
aflion  of  eleilricity,  the  dilatation  cannot  be  extended  beyond  one-fixth  its  ufual  amount. 

4.  The  decompf  nent  of  the  water  is  not  a  metallic  fubftance,  becaufe  carbonated  hydro- 
genous gas  is  expanded  when  in  contadl  only  with  a  glafs  tube  and  gold,  a  metal  which  has 
no  power  of  fi  par.iting  water  into  its  formative  principles. 

5.  The  oxygen  of  the  wa.ter  (when  the  eledric  fluid  is  pafletf  through  carbonated  hydro- 
genous gas,  that  holds  this  fubftance  in  folution)  combines  with  the  carbon,  and  forms  car- 

*  Since  this  paper  was  written,  I  have  extended  the  inquiry  to  phofphorated  hydrogenous  gas,  which  ex- 
pands eiiuall;^  with,  the  parboiiated  hydrogen  ;  lofes  its  property  of  inflaming  when  brought  into  contadt  with 
•jtyjjeiieus  gas,  and  affords  eyident  traces  of  a  produilion  of  pbofphorous  or  phofphoric  acid. 

benl< 


948  Obfervatmi  on  Bitumens, 

bonic  ac'd,    This  produ£tl0n  of  carbonic  acid,  therefore,  adds  to  the  dilatation  occafioncd 
by  the  evolution  of  hydrogenous  gas. 

6.  There  is  not,  by  the  adtion  of  the  cledric  matter  on  carbonated  hydrogenous  gas,  any 
generation  of  azotic  gas. 

7,  Carbon,  it  appears,  therefore,  from  the  united  evidence  of  thefe  faifls,  is  ftill  to  be  con- 
fjdered  as  an  elementary  body  s  that  is,  as  a  body  with  the  compoGtion  of  which  wc  are  unac- 
quainted, but  which  may  neverthelefs  yield  to  the  labours  of  fome  future  and  more  fuccefsful 
analyft. 


II. 

OlfervaUot7s   on  Bituminous   SubJIances,  with  a   Defcr'tplion  of  the  Farteties  of  the  Ehjlic 
Bitumen.     By  CHARLES  Hatchett,  Efq.  F.R.S.  Lond.  and  Edin.  F.L.S.  U'c 

£ConcIiided  from  Page  209,  Vol.II.] 

X  H  E  chara£ters  of  bitumen  are  much  more  apparent  in  turf  and  peat,  than  in  the 
greater  part  of  the  foflil  woods.  Turf  is  well  known  to  be  compofed  of  the  parts  of  vegetables, 
fuch  as  fmall  roots,  twigs,  &c.  mixed  with  a  portion  of  petroleum ;  and  peat  is  the  fame, 
excepting  that  it  generally  contains  more  of  earthy  matter,  or  that  the  vegetables  have 
undergone  a  more  complete  decompofition. 

The  boggy  nature  of  the  places  in  which  they  are  found,  proves  that  a  certain  degree  of 
maceration  is  neceflary  to  form  the  bituminous  matter  which  they  contain ;  and  I  have 
already  noticed,  that  every  fadi  appears  to  demonftrate,  that  the  bitumen  is  a  produ6l  of 
thofe  vegetables,  the  remains  of  which  conftitute  the  other  ingredient  of  turf  and  peat. 

The  different  proportion  of  vegetable  matter,  of  bitumen,  and  of  earth,  together  with  the 
different  ftate  of  the  bitumen,  as  well  as  the  degree  of  perfeiStion  refpefting  the  formation  of 
it  from  tlie  vegetable  principles,  contribute  to  alter  the  properties  and  charadlers  of  the 
compound,  and  thus  produce  varieties.  It  is  believed  that  thefe  fubftances  have  been 
materially  concerned  in  the  formation  of  pit-coal,  and  fome  eminent  mineralogifts  maintain 
that  there  is  an  uninterrupted  feries  which  conne6ls  the  varieties  of  turf  and  peat  with  thofe 
of  coal  *. 

SECT.   V. 

LITTLE  need  be  faid  concerning  thofe  mixtures  of  bitumen  with  meta'i  or  their  oxides 
which  are  fomctimes  called  the  bituminous  ores  of  mercury,  copper  and  iron,  for  they 
fhould  rather  be  arranged  with  the  adulterated  or  impure  bitumens.  Few  of  them  contaia 
the  metallic  ingredient  in  a  proportion  fufficient  to  caufe  the  compound  to  be  worked  as  an 
ore ;  and  the  only  exception  with  which  I  am  acquainted,  is  the  fubftance  found  at  Idria,  in 
Carniolia,  compofed  of  mercury  mixed  with  bituminous  matter,  a  quintal  of  which,  accord- 
ing to  Mn  de  Born,  affords  from  fifteen  to  twenty  pounds  of  mercury  f . 

•  Man  findet  in  der  natur  einen  vinunterbrochenen  ijbergang  von  dem  rafen  und  papiertorf  durch  den  moor 
■•der  fumpftorf  in  den  pcchtorf,  und  von  diefem  in  die  braun  fchiefer  und  pechkohle. — Widenmann,  p.  630, 
t  Catalogue  dela  Colkftion  des  Foffiles  de  Mite,  de  Raab,  torn.  ii.p.  i94,  348,  and  400. 

SECT.  VI. 


Kevj  Species  if  Bitunun  refanhUng  India  Ruhher.  249- 

SECT.  VI. 
■  FROM  the  preceding  obfervatlous  it  will  appear,  that  although  I  have  firft  mentioneu 
naptha  in  order  that  I  might  be  better  underftood  in  refpeft  to  the  degree  of  connexion 
prevailing  between  the  bituminous  fubftances  ;  yet,  to  have  follovfed  them  from  thcii*origira 
and  the  period  of  their  formation,  I  fliould  rather  have  begun  with  thofe  fubftances  which 
nioft  clearly  point  out  how  much  the  vegetable  kingdom  has  contributed  to  the  produdlion 
of  them,  with  the  probable  occafioual  concurrence  of  animal  fubftances. 

That  the  latter  have  contributed  in  fomemeafure  to  the  forming  of  bitumen,  we  can  only 
infer  from  the  veftiges  and  exuvire  of  animals,  which  fo  commonly  accompany  bituminous 
fubftances :  but  no  doubt  can  be  entertained  in  refpe£t  to  vegetables ;  for  it  appears  that 
bitumen  is  formed  from- them  by  long  maceration,  and  by  other  procefles  at  prefent  un- 
known to  us : 

That  when  certain  portions  of  vegetable  matter  remain  undecompofed,  and  are  mixed 
with  the  petroleum  thus  produced,  the  varieties  of  turf  and  peat  are  formed: 

That  wood  in  general  contributes  to  the  produdlion  of  bitumen  ;  but  does  not  fecm  to  re- 
tarn  it,  after  the  formation  of  it,  in  fo  confiderable  a  proportion  as  the  foregoing  fub- 
fl^^ances : 

That  the  bituminous  matter  thus  formed,  and  bccafionally  feparated,  is  in  different  ftates  ■ 
according  to  the  degree  of  infpiflation  : 

And  laftly,  with  various  proportions  of  carbonic  and  earthy  matter,  it  forms  jet,  coal,  and 
bituminous  fchiftus;  and  with  metallic  fubftances  it  produces  thofe  compounds  called  bitu-^ 
minous  ores, 

SECT.    VII. 

ABOUT  the  year  1786  a  new  fpecies  of  bitumen  was  difcovered  near  Caftleton,  ii; 
Derbyfhire,  which  much  refembles,  in  elafticity  and  colour,  the  fubftance  known  by  the 
name  of  cahout-chou,  or  Indian  rubber. 

M.  de  Born  was,   I  believe,  the  firft  who  mentioned  it*;  but,   as  he  appears  to  have 
known  only  one  variety  of  this  fingular  fubftance,  I  am  induced  to  hope  that  a  defcription  - 
of  many  other  varieties,   which  have  fmce  been  found,  will  not  be  unacceptable  to  this 
Society. 

The  elaftic  bitumen,  which  refembles  the  cahout-chou,  was  firft  difcovered  in  the  cavities 
of  a  vein  in  the  lead-mine  called  Odin,  which  is  near  the  bafe  of  Mamtor,  to  the  north  of  :' 
Caftleton.     The  ore  of  this  mine  (which  is  fuppofed  to  be  one  of  the  moft  ancient  in  Eng-  -  » 
land)  is  galena,  accompanied  by  fluor,  calcareous  and  heavy  fpars,  quartz,  blende,  calamine, 
felenile,  afphaltum,   and  the  elaftic  bitumen,  although  the  latter  is   now  rarely   found  f,  , 
Another  fpecies  of  the  elaftic  bitumen  has  within  about  three  years  been  found  in  a  neigh- 
bouring rivulet ;  but  I  fhall  not  at  prefent  notice  it,  as  I  intend  firft  to  deferibe  the  varieties 
of  that  which  was  firft  difcovered,  and  which  refembles  the  cahout-chou..    In  order  to  do  • 
this  with  mare  perfpicuity,  1  fhall  ciefcribe  the  fpecimens.belojiging  to  my.  ColleiStion,  ac«'- 
cording  to  the  mode  in  which  I  have  arranged  them. 

*  Catalogue  de  la  Colleftion  de  Mile,  de  Raab.tom.  ii.  p.  77. 

f  I  am  indtljted  to  the  ingenious  Mr.  White  VVatfon,  of  Bakewell,  .for  much  information.  reQ)e&ing  the  . 
local  ciicumftancts  which  attend  this  bilumeiu 

Voi.  Ik— Sept.  1798.:  Kk  SPECIES 


Sj«  New  SpicUt  if  Elajl'tc  SUumtn, 

SPECIES    theFIRST. 

A,  No.  I. — Elaftic  bitumen  of  a  yellowifli  brown  colour,  part  of  which  is  ahnoft  liquid 
like  petroleum,  and  adheres  to  the  fingers  ;  the  other  part  is  of  a  darker  colour,  of  a  mam- 
niiillary  form,  does  not  adhere  to  the  fingers,  and  is  foft  and  elaftic.  This  is  on  a  grey 
bituminous  limeftone,  with  white  calcareous  fpar  in  the  figure  of  hexaedral  pyramids,  form- 
ing that  which  is  called  the  dog-tooth  fpar. 

A,  No.  2. — Bitumen  of  a  yellowifh  brown,  partly  liquid,  and  partly  elaftic,  which,  how- 
ever, adheres  to  the  fingers ;  on  pale  grey  limeftone,  with  cryftals  of  white  fluor  fpar,  blende, 
and  galena. — On  another  part  of  the  limeftone  are  fome  globules  of  bitumen  of  a  rcddjfli 
brown,  perfedly  hard  and  brittle. 

A,  No.  3. — Dark  brown  bitumen  of  a  ftalaGitical  form,  hard,  but  in  fome  degree 
elaftic. 

A,  No.  4. — Bitumen  of  a  reddifti  brown,  in  the  form  of  globules,  fome  of  which  arc 
elaftic,  and  others  hard ;  on  brownifli-grey  limeftone,  accompanied  by  cryftallized  white 
fluor,  dogtooth  calcareous  fpar,  and  pyrites  in  fmall  cryftals,  fome  of  which  are  on  the  fur- 
face  of  the  globules  of  bitumen. 

A,  No.  5. — The  fame  of  a  darker  brown,  of  a  ftala£titical  form,  hard  and  brittle;  on 
pale  brown  calcareous  fpar,  impregnated  with  bitumen. 

A,  No.  6. — Bitumen  of  a  dark  reddifti  brown,  very  hard  ;  on  pale  brown  fparry  ftink- 
ftone,  with  grey  limeftone,  in  which  are  fome  coralloides. 

A,  No.  7. — Bitumen  of  a  dark  yellowiih  brown,  elaftic,  but  very  foft,  fo  that  it  adheres 
to  the  fingers. 

A,  No.  8.— The  fame  thinly  fpreadover  grey  fparry  ftink-ftone. 

A,  No.  9. — Bitumen  of  a  brownifli  olive  colour,  which  becomes  reddifti  brown  by  the 
air,  but  when  oppofed  to  the  light  it  appears  femi-tranfparent,  and  of  a  yellowifti  brown  in- 
clining to  or?.nge.     It  is  foft,  very  elaftic,  and  (when  recently  cut)  adheres  to  the  fingers, 

A,  No.  10. — ^The  fame  of  a  darker  brown,  and  harder  in  a  fmall  degree.  The  fpecific 
gravity  of  thisfpecimen  is  0,9053;  water  being  eftimated  at  10,000  (q.  !,ooo  ?)  at  temp.  60°. 

A,  No.  1 1 . — Bitumen  of  a  dark  brown,  harder  than  the  former.  This  exactly  refcmbles 
the  cahout-chou  in  the  degree  of  elafticity,  and  in  the  property  which  it  pofleircs  of  removing; 
the  traces  of  black-lead, 

A,  No.  1 2, — The  fame,  but  rather  harder. 

A,  No.  13. — The  fameof  ablackifhbrown,  which  is  flightly  elaftic  when  the  weather  is 
warm,  but  is  brittle  when  cold. 

A,  No.  14. — The  fame  of  a  blackifh  brown,  nearly  black,  which  fcarcely  poficiTes  any 
elafticity;  it  breaks,  and  rcfembles  afphaltum  in  luftre,  colour  and  fra£lure. 

A,  No.  IS.—- The  fame  of  a  reddifti  brown,  perfedly  hard  and  brittle.  The  charaflers 
of  afphaltum  are  complete  inthis  fpecimen.     The  fpecific  gravity  is  10,233.  (q.  1,233  '■) 

The  other  fpecles  of  elaftic  bitumen,  which  I  fhall  diftinguifli  by  the  letter  B,  has  been 
found  during  the  laft  three  years  in  a  rivulet  which  runs  at  the  bafe  of  Mamtor,  from  weft 
to  caft,  at  a  fmall  diftance  from  Odin  mine. — The  varieties  of  it,  in  my  poflbffion,  are  as 
fc/U»w :— — 

6  SPECIES 


Oh/ervatkns  tn  the  ElaJlUliy  df  Bltumm,  5}e| 

SPECIES    THE    SECOND. 

B,  No.  I. — Elaftic  bitumen,  which,  recently  cut,  cxadlly  refembles  fine  clofe  cork  in 
colour  and  texture,  but,  by  the  air,  in  a  few  days  it  becomes  of  a  pale  reddifh  brown.— This 
forms  a  thin  coat,  which  completely  covers  a  mafs  of  elaftic  bitumen,  which  is  foft,  and  of 
a  brownifti  olive  colour,  like  A,  No.  9. 

B,  No.  2. — ^The  fame,  excepting  that  the  coat  or  cruft  is  much  thicker. 

B,  No.  3. — ^The  fame,  but  the  coating  is  thicker  than  that  of  No.  2,  and  the  brownifh 
olive-coloured  bitumen  much  lefs  in  quantity. 

B,  No.  4.— The  fame,  excepting  that  the  greater  part  of  the  mafs  refembles  cork,  fo  that 
only  a  very  fmall  nucleus  of  the  brown  bitumen  remains  *. 

B,  No.  5. — The  fame,  excepting  that  the  bitumen,  which  is  coated,  is  in  the  ftate  of 
afphaltum.     The  fpecific  gravity  of  this  fpecimen  is  0,9881. 

B,  No.  6. — Elailic  bitumen,  the  whole  mafs  of  which  refembles  fine  cork. — The  fpecific 
gravity  is  0,9748. 

B,  No.  7. — The  fame,  but  friable,  and  apparently  paffing  by  decompofition  into  an 
ochraceous  coloured  powder. 


THE  varieties  of  the  firft  fpecics  of  the  elaftic  bitumen,  or  that  which  is  like  the  cahout- 
'chou,  evidently  appear  to  be  formed  from  a  naptha  or  petroleum,  which,  like  that  which  pro- 
duces the  other  fimple  bituminous  fubftances  formerly  mentioned,  is  fufceptible  of  various 
degrees  of  infpiflation. 

All  the  varieties  of  the  firft  fpecies,  from  No.  i,  to  No.  15,  may  be  regarded  as  thus  form- 
ed ;  for  in  thefe  we  can  trace  all  the  modifications  comprehended  between  petroleum  and 
afphaltum  :  with  this  difference,  that  the  intermediate  modifications  of  this  fpecies  have  the 
remarkably  property  of  elafticity  which  is  the  moft  complete  in  the  variety  which  occupies 
the  middle  place  between  petroleum  and  afphaltum. 

The  fecond  Ipecies  B,  or  that  which  resembles  cork,  appears  fo  different  from  that  marked 
A,  that  it  is  not  at  firft  eafy  to  conceive  how  they  are  connected,  or  at  leaft  the  difficulty 
muft  appear  great  to  thofe  who  have  only  feen  fpecimens  of  each   fpecies  complete  in  their 
refpe£tive  charailers.     But,  from  an  attentive  examination  of  many  fpecimens,  and  particu- 
larly of  thofe  which  I  have  defcribed,  I  am  convinced  that  the  varieties  of  the  fpecies  B  are 
only  modifications  of  the  fpecies  A,  produced  probably  by  long  maceration  in  the  water  of 
the  rivulet  in  which  this  fpecies  is  found,  to  the  effects  of  which  we  may,  with  fome  appear- 
ance of  reafon,  add  the  viciffitudes  of  the  feafons,   of  air,  and  of  the  weather  in  general,  as 
well,  as  thofe  of  reiterated  moifture  and  drynefs  occafioned  by  the  rife  and  fall  of  the  water  of 
the  rivulet  -,  and  what  feems  to  corroborate  this  opinion  is,  that  the  fubftance,  like  cork,  in- 
crufts  the  fpecies  A,  and  appears  to  be  only  a  change  which  has  penetrated  deeper  into  the 
fubftance  of  it  in  proportion  to  the  duration  of  the  caufes  which  I  have  mentioned,  fo  that  at 
length  the  original  fubftance  no  longer  remains  in  its  primitive  ftate.     I  do  not  believe, 
however,  that  this  change  arifes  from  any  alteration  in  the  conftituent  principles,  but  merely 

*  Oue  ef  the  fpecimens  in  my  poffeflion,  fimikr  toB,  No.  4,  weighs  between  13  and  i4pouads. 

K  k  2  feoia 


•5<;i  XJbftrvatlons  and  Experiments  on  ElaJ}ic  Bitumen, 

from  a  partial  and  minute  dif-union  or  difintegracion  of  the  particles  of  the  original  fiibfknct, 
as  both  fpecies  melt  into  one  whiclj  is  perfedlly  fiinilar.  I  muft  alfo  add,  that  the  fpecies  A 
burns  cafily,  and  with  rapidity  ;  but  the  fpecies  B  burns  with  fome  difficulty,  and  crackles  as 

'if  it  had  imbibed  a  quantity  of  water. 

I  have  remarked,  when  the  different  varieties  of  the  elaftic  bitumen  were  melted,  that  they 

-completely  loft  the  claftic  property,  and  a  quantity  of  air  or  gas  appeared  to  be  difenga^ed, 
particularly  from  the  fpecies  B.  I  alfo  obfcrvtd,  that  the  fubftanccs  which  remained  after 
this  operation,  correfpondcd,  in  refpeil  to  confiftence,  with  thofe  which  had  been  employed, 
as  the  following  table  will  fhevv  : 

A,  No.  7  and  8 produced  a  thick  h'quid  petroleum,  not  apparently  different  from  that 

which  is  commonly  known. 
A,  No.  9 produced  a  thicker  petroleum,  approaching  to  mineral  tar. 

A,  No.  1 1  and  I2  . . .  produced  mineral  tar. 

B,  No.  6 produced  the  fame,  approaching  to  mineral  pitch. 

A,  No.  13 produced  mineral  pitch. 

A,  No.  14  and  15  .. .  did  not  fuffer  any  change,  but  remained  as  at  firft,  with  all  the  cha- 

rafters  of  afphaltum. 

From  what  I  have  related,  I  fufpe£t  that  the  elaftic  property  is  occafioned  by  the  inter- 
vpofition  of  very  minute  portions  of  air  or  fome  other  elaftic  fluid  between  the  parts  of  the 
bitumen,  and  that  this  takes  place  by  reafon  of  iCcnQ  unknown  caufc  at  the  time  of  forma- 
tion ;  but  when  thefe  bitumens  are  melted,  the  elaftic  fluid  is  liberated,  and  the  mafs  lofcs 
that  fine  fpongy  texture  which  I  fufpect  to  have  been  the  caufe  of  the  elaftic  property  *. 

Derbyfhire  is  well  known  as  a  country  which  exhibits,  in  the  moft  ftriking  manner,  the 
remarkable  changes  which  our  globe  'has  fufFered.  In  every  part  of  it,  the  moft  indifpatablc 
evidences  appear  of  fome  great  and  extraordinary  revolution  j  and  there  is  not  any  place 
where  extraneous  foffils,  fuch  as  the  remains  and  imprefftons  of  vegetables  and  animals,  arc 
more  abundant. 

Bitumen,  in  other  countries,  is  moft  commonly  found  where  thefe  prefent  themfelves; 
and,  in  like  manner,  there  are  few  countries  which  abound  fo  much  with  bitumen  as  Derby- 
{hire. 

Whoever  has  examined  the  limeftone  rocks  about  Matlock,  and  moft  other, places  in  this 
county,  muft  be  convinced  of  the  truth  of  this  aflertion. 

The  limeftone  and  calcareous  fpars  alfo,  where  the  elaftic  bitumen  is  found',  are,  for  the 
greater  part,  in  the  fameftate  ;  fo  that  no  doubt  can  be  entertained  but  that  this  bitumen  has 
had  the  fame  origin  as  thofe  which  are  more  generally  known ;  and  it  would  undoubtedly 
have  been  confounded  with  them,  had  it  not  been  difcovcred  when  paffing  from  the  liquid 
to  the  folid  ftate. 

*  The  elaftic  bitumen,  A,  No.  9.  when  digeflcd  in  fulphuric  ether  in  a  temperature  of  about  55°,  is  partly 
diffolvcd.  The  folution  is  yellowiih  brown  when  oppofed  to  the  light ;  but,  vvhen  otherwife  viewed,  is  lil^c 
the  bitumen,  that  is,  of  a  browniih  olive  colour.  By  fpontancous  evaporation,  the  etheric  folutJon  leaves  a 
yeliowilb  brown  bitumen,  which  is  totally  devoid  of  elafticity.  The  undilTolved  portion  (like  the  cahout-efeou 
under  fimilar  circumflances;  is  foftened,  and  is  much  increafed  in  bulk. 

The  fpecies  B,  No.  6.  cut  into  very  thin  flices,  communicates  a  yellow  tinge  to  fulphuric  ether  j  in  other 
refpefts  It  is  but  Ihtle  affefted. 

The 


On  the  Fhyficnl  and  Political  Gcop'aphy  of  North  Africa.  253 

"The  elementary  principles  of  bitumen  are,  hydrogen,  carbon,  fometimes  azote,  and  pro- 
bably fome  oxygen,  which,  by  its  a£lion  on  the  other  principles,  tends  to  form  the  concrete,; 
bitumens,  and  alfo  produces  that  portion  of  acid  obtained  by  chemical  operations.  Thefe 
fame  principles,  hydrogen  and  carbon,  conflitute  the  vegetable  oils  and  refins ;  and  the  fame, 
with  fome  azote,  form  the  oils  and  greafe  of  animals.  Now  it  is  Icnown  that  very  fmall 
changes  in  the  rcfpeftive  proportions  of  thcfc  ingredients,  and  in  the  circurnflanccs  which 
attend  the  combination  of  them,  will  caufe  confiderable  variations  in  the  nature  of  the  pro- 
dufts;  and  in  like  manner,  it  appears  very  probable,  that  when  the  organized  bodies  in  their  ' 
recent  ftate,  and  in  the  full  poffeifion  of  the  above-mentioned  principles,  have  been  buried'in 
a  fituation  where  thefe  principles  have  been  long  elaborated  under  certain  favourable  circuin- 
ilances,  and  fubje<fled  to  the  adion  of  mineral  bodies  ;  I  fay  that  it  appears  highly  probable, 
that  a  new  combination,  which  we  call  bitumen,  may  be  formed,  which,  although  different 
in  fome  refpc£ls  from  the  vegetable  and  animal  products,  flill,  however,  retains  many  cha- 
rafters  of  thofe  fubftanccs  from  the  principles  of  which  it  has  been  formed. 

Hammersmith, 
April 26,  lyg-]. 


III. 

Olfervattorts  on  the   Phyfttal  and   Political  Geography  of  North    Africa. 

By  James  Rennml-,  Efq.  F.  R.  S.  * 

J.  O  our  view.  North  Africa  appears  to  be  compofed  of  three  diftinft  parts,  or  members. 
The  firft  and  fmalleft  is  a  fertile  region  along  the  Mediterranean^  lying  oppofite  to  Spain, 
Franc»,  and  Italy  (commonly  diflinguifhed  by  the  name  of  Barbary)  ;  and  which,  coiild  we  . 
fuppofe  the  weflern  bafon  of  the  Mediterranean  to  have  once  been  dry  land  (bating  a  lake  t 
or  recipient  for  the  furrounding  rivers),  might  be  regarded  as  a  part  of  Europe  j  as  pofTefling. 
much  more  of  the  European  than  the  African  charadcr.  \ 

The  fecond  part  is  what  may  be  deemed  the  body  of  North  Africa,  comprifed  betweetr' 
Cape  Verd   and  the  Red  Sea,   on  the  eaft  and   weft;  and  having  the  Great  Defert  (or ^ 
Sahara)  and  its  members,  on  the  North  ;    the  Ethiopia  ocean  and  South  Africa,  on  the  op-  - 
pofite  fide.     The  prominent  feature  of  -this  immenfe  region  Is  a  vaft  belt  of  elevated  land  of 
great  breadth,  often  fwelling  into  lofty  mountains,  and  running  generally  from  weft  to  eaft,    . 
about  the  tenth  degree  of  latitude.     Its  weftern  extremity  feems  to  be  Cape  Verd  j  the 
mountains  of  Abyffinia,  the  eaftern.     To  the  north,  its  ramifications  are  neither  numerous 
nor  extenfive,  if  we  except  the  elevated  tradt  which  turns  the  Nile  to  the  northward  beyond 
Abyffinia.     Towards  the  fouth  no  particulars  are  known,  fave  that  a  multitude  of  rivers 
fome  of  them  very  large,  defcet.c'  from  that  fide  and  join  the  Atlantic  and  Ethiopic  feas,  from 
the  Rio  Grande  on  the  weft  to  Cape  Lopez  on  the  eaft;  proving  inconteftably  that  by  far 
the  greateft  proportion  of  rain  water  falls  on  that  fide  during  the  periodical  feafon  of  the 

»  Copied  by  pcrmiflion  from  his  "  Geographical  Tlluftrationsof  Mr.  Park's  Journey,''  in  the  Proceedings  of 
the  African  Aflbciation,  1 798.    On  this  fubjeft  fee  likewife  our  Account  of  Books  in  the  prefent  Number     N. 


254      ,  Phyfical  and  Poltthal  Geography  of  North  Africa. 

S.  W.  winds ;  which  corrcfponds   in  all  its   circumllances  with   the  fame  monfoon   in 
India  *. 

To  tlie  north  of  this  belt,  with  the  exception  of  the  Egyptian  Nile,  the  waters  conform 
generally  to  the  dirc^Slion  of  the  high  land  ;  paffing  at  no  great  diftance  (comparatively) 
from  its  bafe  to  the  right  and  left ;  as  if  the  furface  of  the  Sahara  had  a  general  dip  to  the- 
fouthward  \.  Thefe  rivers  moreover  receive  all  their  fupplies  from  the  fouth  j  no  dreams 
of  any  bulk  being  collcded  in  the  Defert. 

In  order  to  produce  this  efFcft,  there  muft  neceflarily  be  a  vaft  hollow  in  the  interior  of 
Africa,  between  the  high  land  of  Nubia  on  the  eaft,  and  Manding  on  the  weft ;  and  of 
which  the  mountains  and  defert  form  the  other  two  fides.  Nor  is  this  ftate  of  things  un- 
exampled in  the  other  continents.  In  Afia,  the  hollow,  to  whofe  waters  the  Cafpian  and' 
Aral  ferve  as  recipients,  is  no-  lefs  extenfive  than  the  one  juft  mentioned  ;  reckoning  from 
the  fources  of  the  Wolga  to  thofe  of  the  Oxus ;  (which  latter  has  ever  communicated  with 
the  Cafpian,  cither  throughout  the  year  or  during  a  part  of  it :}  the  diiTcrence  is,  that  lit 
Afia  a  greater  portion  of  the  hollow  is  filled  up  with  water  than  in  Africa-. 

The  third  part  is  of  courfe  the  Great  Defert  (or  Sahara)  and  its  members;  confifting  of 
the  lefler  deferts  of  Bornou,  Bilma,  Barca,  Sort,  &c.  This  may  be  confidfered  as  an  oceah 
OF  SAND  J,  prefenting  a  furface  equal  in  extent  to  about  one  half  of  Europe^  and  having  its 
gulfs  and  bays  ;  as  alfo  its  iflands  fertile  in  groves  and  paftures,  and  in  many  inftances  con- 
taining a  great  population  fubjed  to  order  and  regular  government.  The  great  body  or 
weftern  divifion  of  this  ocean,  comprifed  between  Fezzan  and  the  Atlantic,  is  no  lefs. 
than  50  caravan  journeys  acrofs  from  north  to  fouth  ;  or  from  750  to  800  G.  miles  ;  and 
double  that  extent  in  length  :  without  doubt  the  largeft  defert  in  the  world.  This  divifion- 
contains  but  a  fcanty  portion  of  iflands  (or  oafes),  and  thofe  alfo  of  fmall  extent :  but  the 
eaftern  divifion  has  many ;  and  fome  of  them  very  large.  Fezzan,  Gadamis,  Taboo, 
Ghanat,  Agadez,  Augela,  Berdoa,  are  amongfl:  the  principal  ones  :  hefides  which  there  are 
a  vaft  number  of  fmall  ones.  In  effed  this  is  the  part  of  Africa  alluded  to  by  Strabo  11, 
when  he  fays  from  Cneius  Pifo,  that  Africa  may  be  compared  to  a  leopard's  fkin.  I  conceive. 
the  reafon  why  the  oafes  are  more  common  here  than  iii  the  weft,  is,  that  the  ftratum  of 
fand  is  fliallower  from  its  furface  to  that  of  the  earth  which  it  covers.  In  other  words,  that 
the  water  contained  in  that  earth  is  nearer  to,  the  furface  ;  as  in  moft  of  the  oafes  it  fprings 
up  fpontaneoufly  §.  Can  any  part  of  the  caufe  be  affigned  to  the  prevalent  eafterly  winds, 
which,  by  driving  the  finer  particles  of  fand  to  leeward,  may  have  heaped  it  up  to  a  hio^her 
level  in  the  Sahara  than  elfewhere  .' 

The 

•  A  ridge  ftretches  to  the  fouth  through  the  middle  of  South  Africa,  and  forms  an  impenetrable  barrier 
between  the  two  coafts.  M.  Correa  de  Scrra  informs  me,  that  the  Portuguefe  in  Congo  and  Angola  have 
never  been  able  to  penetrate  to  the  coaft  of  the  Indian  Ocean. 

Mr.  Bruce  learned  (vol.  lii.  p.  668.)  that  a  high  chain  of  mountains  from  b"  runs  fouthward  through  tke 
middle  of  Africa.     He  fuppofes  the  gold  of  Sofala  to  be  drp.wn  from  thcfe  mountains,  (p.  669.) 

+  Circumftances  have  fliewn,  that  it  declines  to  the  eaiiward  alfo. 

+  "  A  wild  expanfe  of  lifelefs  fand  and  fky  !"     Thomson, 

H  Page  130. 

I  Water  is  found  at  the  depth  of  afew  feet  in  Feizaa  (Africau  Aflbc.  Q^p.  96.  O,  p.  146.)    The  fame  ia 

fai4 


\ 


.^■^ 


Phyjfcal  and  Political  Geography  of  North  Africa,  aj  5 

The  fprings  no  doubt  have  produced  the  oafes  themfelves,  by  enabling  ufeful  vegetables 
to  flourifli,  and  confequently  population  to  be  cftablifhed.  That  the  Defert  has  a  dip  to- 
wards the  eaft  as  well  as  the  fouth,  feems  to  be  proved  by  the  courfe  of  the  Niger  alfo. 
Moreover  the  higheft  points  of  North  Africa,  that  is  to  fay,  the  mountains  of  Mandinga  and 
Atlas,  are  fituated  very  far  to  the  weft. 

The  Defert  for  the  moft  part  abounds  with  fait.  But  we  hear  of  fait  mines  only  in  the 
part  contiguous  to  Nigritia,  from  whence  fait  is  drawn  for  the  ufe  of  thofe  countries  as  well 
as  of  the  Moorifli  ftates  adjoining  ;  there  being  no  fait  in  the  Negro  countries  fouth  of  the 
Niger  *.     There  are  fait  lakes  alfo  in  the  eaftern  part  of  the  Defert. 

The  great  ridge  of  mountains  and  its  branches  arc  very  productive  in  gold;  but  more 
particularly  in  the  quarters  oppofite  to  Manding  and  Bambouk  on  the  weft,  and  Wano-ari 
on  the  eaft.  It  may  perhaps  admit  of  a  doubt,  whether  the  gold  is  brought  down  at  the 
prefent  time  by  the  numerous  fountains  that  form  the  heads  of  the  Niger  and  Senegal  rivers; 
or  whether  it  has  been  depofited  in  the  lower  parts  of  their  beds  at  an  earlier  period  of  the 
world  ;  and  that  the  fearch,  inftead  of  being  facilitated  by  the  periodical  floods,  is  on  the  con- 
trary only  to  be  purfued  with  cfFe£t  when  the  waters  are  low. 

Tombu£loo  is  reckoned  the  mart  of  the  Mandinga  gold,  from  whence  it  is  diftributed  over 
the  northern  quarters  of  Africa  by  the  merchants  of  Tunis,  Tripoly,  Fezzan,  and  Morocco  j 
all  of  VI  hom  refort  to  Tombucfloo.  Moft  of  it  no  doubt  afterwards  finds  its  way  into  Europe. 
It  may  be  remarked  alfo,  thst  the  gold  coaft  of  Guinea  (fo  called  doubtlcfs  from  its  being 
the  place  of  traffic  for  gold  duft)  is  fituated  nearly  oppofite  to  Manding:  but  whether  the 
gold  brought  thither  has  been  wafhed  out  of  the  mountains  by  the  northern  or  fouthern 
ftreams,  I  know  not :  it  may  be  both  \.     Uegombah,   another  country  faid  to  be  very  pro- 

duiSlivc 

faid  by  Pliny,  concerning  this  quarter  of  Africa ;  lib.  v.  c.  5.  But  farther  to  tli£  N.  W.  on  the  edge  of  th; 
Defert,  and  in  the  country  of  Wadreag  in  particular,  (Shaw,  p.  135.)  wells  are  dug  to  an  amazing  depth,  and 
water  mixed  with  fine  fanJ  fprings  up  fuddcnly,  and  fomctimes  fatally  to  the  workmen.  The  Doitor  tells  us^ 
ttiat  the  people  call  this  abyfs  of  faud  and  water,  "  the  fea  below  ground."  Exaflly  the  lame  ftate  of  things 
'  cxifts  in  the  country  round  London,  where  the  fand  has  in  fcveral  cafes  nearly  filled  up  tlic  wells.  (See  Phil. 
Traiif.  for  1797.)  The  famous  well  lately  dug  by  Earl  Spencer  (at  Wimbledon),  of  more  than  560  feet  in 
depth,  has  fevcral  hundred  feet  of  fand  in  it. 

*  This  quality  of  the  African  Defert  was  familiarly  known  to  Herodotus  (Mclpom.  c.  iSi,  et  fcq.)  He 
knew  alio  that  there  was  fait  in  abundance  in  the  northern  parts.  But,  as  the  inhabitants  in  that  quarter  can 
furiiifli  themfelves  with  fait  of  a  better  quality  from  the  fea,  the  mines  are  not  wrought. 

t  Some  writers  have  faid,  that  there  arc  gold  mines  in  the  neighbourhood  of  Mina,  on  tiie  gold  coaft  ;  others 
that  the  gold  is  rolled  down  by  the  rivers  to  that  neighbourliood.  Both  may  be  true.  But,  on  the  other  hand, 
it  is  faid  that  the  gold  of  Wangara  is  alfo  brought  forfale  to  the  fouthern  coaft. 

It  is  difficult  to  coliccive  any  other  adequate  caufc,  than  the  exchange  of  the  gokl  of  the  inland  countries 
for  the  introduftion  of  fo  vaft  a  quantity  of  kowry  (hells,  which  are  carried  from  Europe  to  the  coaft  of 
Guinea,  and  pafs  for  fmall  money  in  the  countries  along  the  Niger  from  Bambara  to  Kalfina,  both  inclufive. 

I  am  informed  from  authority,  that  about  100  tans  of  kowrics  are  annually  fljippcd  from  England  alone  to 
Guinea.  Thefe  are  originally  imported  from  the  Maldive  iflands  into  Bengal ;  and  from  Bengal  into  Eng- 
land. In  Bengal  1400  more  or  lefs  are  equal  to  a  (hilling:  and  yet,  notwithftanding  the  incredible  fmailnefs  of 
the  ^denomination,  fomc  article  in  the  market  may  be  purchafed  for  a  fingle  kowry.  But  in  the  inland  parts  of 
Africa  they  arc  about  ten  times  as  dear,  varying  from  izo  to  280.  Mr.  Beaufoy  was  told,  that  In  KalTina 
they  were  at  the  rate  of  about  250.    And  Mr,  Park  reports,  that  they  are  about  the  fame  price  at  Sego :   but 

cheaper 


2S6  Fmfical' and' Political  Geolt'a^hf  of  North  j^rim^  <i 

duftive  in  gold  *,  muft  by  tts.fituation  lie  diredly  oppofite  to  the  gold  coaft  :  for  it  lies  im- 
mediately to  the  ea(t  of  Kong  (the  Gonjah  of  Mr.  Beaufoy  and  the  Conche  of  D'Anville  +.J 
The  people  of  Fezzan  trade  to  Kong. 

.  The  trianguUr  hilly  tradt  above  commemorated,  (p.  71  of  the  "  Illuftrations")  which 
proje£b  northward  from  the  higheft  part  of  the  belt,  and  contains  Handing,  Bamhouk,  &c. 
is  alfo  abundant  in  gold;  particnlarly  in  the  quarter  towards  Bambouk,  where  it  is  found  in 
mines  -,  and  that  chiefly  in  the  middle  level  \.     (See  alfo  p.  71.) 

Wangara  appears  to  have  been  in  its  time  nearly  as  rich  as  Manding  in  this  metal.  The 
Arabs  name  it  Bclad  al  Tebr,  or  the  country  of  gold  \\.  Edrifi,  Ibn  Al  Wardi,  and  Leo,  bear 
teftimony  to  its  riches.  They  fay  that  the  gold  is  found  in  the  fands  after  the  periodical 
inundation  of  the  Niger  (which  is  generally  over  the  country)  is  abated  §.  Leo  alone  ** 
fays,  that  the  gold  is  found  in  the  fouthern  quarter  of  the  kingdom  ;  which  appears  very 
probable,  as  the  mountains  lie  on  that  fide  :  fo  that  it  may  be  concluded,  that  the  gold  fand 
has  not  been  brought  there  by  the  Niger,  but  by  fmaller  rivers  that  defcend  immediately 
from  thefe  mountains.  That  a  part  of  Wangara  is  bounded  by  mountains,  we  learn  from 
Edrifi :  for  the  lake  on  which  Reghebil  ftands  has  mountains  hanging  over  its  fouthern 
ihore  tt- 

It  is  fuppofed  that  moft  of  the  countries  bordering  on  thefe  mountains  fhare  in  the  riches, 
contained  within  them,  by  means  of  the  rivulets  {J.  But  conlldering  how  amazingly  pro- 
ductive in  gold  the  fkeams  of  this  region  are,  it  is  wonderful  that  Pliny  fhould  not  mention 
the  Niger,  as  one  of  the  rivers  that  rolls  down  golden  fands- :  for  although  he  fpeaks  of  the 
Tagus  and  others  in  different  quarters,  no  African  river  is  mentioned  |||].  And  yet  Herodotus 
knew  that  the  Carthaginians  bartered  their  goods  for  gold,  with  the  Africans  on  the  fea 
coaft  beyond  the  pillars  of  Hercules  ;  which  was  contrived  without  the  parties  feeing  each 
other  §§. 

The  common  boundary  of  the  Moors  and  Negroes  in  Africa  forms  a  fhriking  feature,  as. 
well  in  the  moral  as  the  political  and  phyfical  geography  of  this  continent.     The  Moors  de- 
fcendants  of  Arabs,  intermixed  with  the  various  colonifts  of  Africa  from  the  earliefi:  to  the.; 

cheaper  at  Tombuftoo,.  which   is  about  the  centre  of  the  kowry  country ;  dearer  towards  Mandiag,  which  is  . 
the  weftern  extremity  of  it.     Hence  they   are  probably  cair.ed  in  the  firft  inftance  to  Tombuftoo,  the  gold 
market;  and  thence  diflributed  to  the  eaft  and  weft.    Their  circulation  feems  to  be  confined  between  Bornou 
and  Manding.    In  Bornou  they  have  a  coinage  of  bafe  metal. 

*  African  Aflbc.  Q^p,  176.  O.  p.  264, 

f  Mr.  Park  fays,  that  Kong  fignifies  mountain  ia  the  Mandinga  language;  which  language  is  in  ufc  fronv 
the  frontier  of  Bainbarato  the  weftern  fea, 
J  Labat,  vol.  iv.  ch.  2. 
11  Bakui,  and  Herbelot;  article  Vankara. 
^See  Edrifi  in  particular,  pages  n  and  12. 

''■*  Page  254.  f  f  Edrifi,  page  11. 

JJ  Mr.  Bruce,  vol.  iii.  p,  647,  fays  the  fameof  the  mountains  of  Dyte  and  Tegla,  which  are  a  continuation  ol 
the  great,  belt,  towards  .^bylfmia. 

nil  Pliny,  lib.,xxxii(.  c,  4,  §§  Melpomene,  c.  196. 

Dr.  Shaw  (p.  302J  fpeaks  of  the  fame  mode  of  traffic  at-  prefent  between  the  Moors  and  Negroes ;  whence 
the  place  of  traffic  ought  to  be  very  far  removed  from  the  Mediterranean.  There  is  a  Similar  ftory  related  by 
Cadsmofta  of  the  exchange  of  &It  for  gold  in  Melli ;  and  by  Dr.  Wadftrom  on  the  windward  coall  of  Guinea. 

lateft 


l^ji/ual  and  Political  Geography  of  N^rth  Africa,  457 

btcft  times  overfpread  the  habitable  parts  of  the  Defert,  and  tke  oafes  within  It ;  and  have 
|)u£hed  their  conquefts  andeftabliflimentsfouthward  ;  preffing  on  the  Negro  aborigines,  wh» 
have  in  ftVeral  inftances  retired  to  the  fouthward  of  the  great  rivers;  but  in  others  preferve 
their  footing  on  the  fide  towards  the  Defert ;  according  to  the  ftrength  or  opennefs  of  the 
fituation.  It  is  probable,  however,  that  the  Negroes,  who  arc  an  agricultural  people,  never 
poflefTed  any  confiderable  portion  of  the  Defert,  which  is  fo  much  better  fuited  to  the  paftoral 
life  of  the  Moors.  It  appears  as  if  matters  had  not  undergone  much  change  in  this  refpeft 
fince  the  days  of  Herodotus;  who  fixes  the  boundary  of  the  Libyans  and  Ethiopians,  in 
other  words,  of  the  Moors  and  Negroes,  near  the  borders  of  the  Niger ;  and  he  apparently- 
pointed  to  the  quarter  in  which  Kalfina  or  Ghana  are  now  fituated  *. 

The  Negroes  in  the  weftern  quarter  of  the  continent  are  of  two  di{lln£l  races,  of  which 
the  leafl:  numerous  are  named  Foulahs  or  Foolahs.  Thefe,  although  they  partake  much  of 
the  Negro  form  and  complexion,  have  neither  their  jetty  colour,  thick  lips,  or  crifpsd  hair. 
They  have  alfo  a  language  diftin£l  from  the  Mandinga,  which  is  the  prevailing  one  in  this 
quarter. 

The  original  country  of  the  Foulahs  is  faid  to  be  a  trait  of  no  great  extent  along  the 
eaftern  branch  of  the  Senegal  river  ;  fituated  between  Manding  and  Kaffon  ;  Bambouk  and 
Kaarta  :  and  which  bears  the  name  of  Foola-doo,  or  the  country  of  the  Foulahs.  But 
whether  this  be  really  the  cafe,  or  whether  they  might  not  have  come  from  the  country  witlv- 
in  Serra  Leona  (called  alfo  the  Foulah  country),  may  be  a  queftion ;  of  which,  more  in  the 
feque!.  The  Foulahs  occupy  at  leaft  as  fovereigns  feveral  provinces  or  kingdoms,  inter- 
fperfed  throughout  the  tra£t  comprehended  between  the  mountainous  border  of  the  country 
of  Serra  Leona  on  the  weft,  and  that  of  Tombu£too  on  the  eaft  ;  as  alfo  a  large  tra£t  on  th« 
lower  part  of  the  Senegal  river;  and  thefe  provinces  are  infulated  from  each  other  in  a  ver/ 
remarkable  manner.  Their  religion  is  Mahomedanifm,  but  with  a  great  mixture  of 
•Paganifm;  and  withlefs  intolerance  than  is  praclifed  by  the  Moors. 

.  The  principal  of  the  Foulah  ftates  is  that  within  Serra;  Leona  ;  and  of  which  Teemboo 
is  the  capital.  The  next  in  order  appears  to  be  that  bordering  on  the  fouth  of  the  Senegal 
river,  and  on  the  JalofFs :  this  is  properly  named  Slratlk.  Others  of  lefs  note  are  Boiidou, 
with  Foota-Torra  adjacent  to  it,  lying  between  the  rivers  Gambia  and  Faleme  ;  Fooladoo 
and  Ikooko  along  the  upper  part  of  the  Senegal  river ;  Wiiflela  beyond  the  upper  part  of 
the  Niger ;  and  Maffina  lower  down  on  the  fame  river,  and  joining  to  Tombucloo  on  the 
we  it. 

The  Moors  have  not  in  any  inftance  el^abliflied  themfelves  on  the  fouth  of  the  great  rivers. 
They  have  advanced  fartheft  to  the  fouth  in  the  vveflern  quarter  of  Africa  ;  fo  that  the  com- 
mon boundary  of  the  two  races  paffes,  in  refpe6t  of  the  parallels  on  the  globe,  with  a  con- 
fiJerable  degree  of  obliquity  to  the  north,  in  its  way  from  the  river  Senegal  towards  Nubia 
and  the  Nile.  Mr.  Park  arranges  the  Moorifli  ftates,  which  form  the  ^owf/Vr  towards 
Nigritia,  together  with  the  Negro  ftates  oppofed  to  them  on  the  fouth,  in  the  Ime  of  his  pro- 
grcfs,  in  the  following  order : 

The  fmall  Moorifh  ftate  of  Gedumah,  fituated  on  the  north  bank  of  the  Senegal  river, 
and  the  laft  that  touches  on  itf,  is  oppofed  to  the  fmall  Negro  kingdom  of  Kajaaga,  on  the 

*  See  Euterpe,  c.  32  ;  and  Melpomene,  c.  197. 

\  The  Moors  appear  to  be  mafters  of  the  northern  bank  of  the  Senegal,  through  the  greateft  part  of  its, 
•navigable  courfe  ;  the  Foulahs  the  fouthern  bank. 

Vot«IL— Sept.  J798.  LI  fouti^ 


«58  Phyjica!  and  Political  Geography  of  North  Africa. 

fouth.  This  latter  occupies  the  extremity  of  the  navigable  courfe  of  the  Senegal,  terminated 
in  this  place  by  the  cataract  of  F'low. 

FroiTi  this  point  the  Negro  and  Foulah  flates  occupy  both  banks  of  the  Senegal  river  to 
its  fource  ;  and  beyond  that  both  banks  of  the  N'ger  (or  Joliba)  likewifc,  to  the  lake  Dibbie, 
fituated  beyond  the  term  of  Mr.  Park's  expedition.  This  fpace  is  divided  unequally  between 
Kaffon,  a  hilly  ftrong  country,  but  of  finall  extent ;  and  which  has  the  Moors  of  JafFnoo  on 
the  north  :  Kaarta  a  confiderable  ftate,  which  has  Ludamar  for  its  oppofite  (a  country  held 
by  Ali,  a  Moorifli  prince,  who  is  loaded  with  infamy  on  the  fcore  of  maltreatment  of  the 
only  two  Europeans  who  appear  to  have  entered  his  country  in  latter  times)  :  Bambara  of 
ftill  more  conI;der<ition,  having  the  Moorifli  kingdom  of  Beeroo  to  the  north  :  and  Maflina, 
a  Foulah  ftate  bordering  alfo  on  the  fouth  of  Beeroo. 

Here  Mi .  Park's  perfonal  knowledge  ends  ;  but  he  learnt  that  Tombucloo  and  Houfla, 
which  fuccced  in  order  to  Maflina,  and  occupy  both  fides  of  the  Niger,  are  Moorifh  dates,. 
though  with  greateft  proportion  of  Negro  fubjefts  :  fo  that  the  river  may  be  confidered  as  the 
boundary  of  the  two  races  in  this  quarter  *. 

Of  the  countries  between  Houfla  and  Kaffina  we  are  ignorant.  The  Defert  fcems  to  ap- 
proach very  near  the  river  (Niger)  in  that  quarter,  whence  a  Moorifh  population  may  be  in- 
ferred. South  of  the  river,  we  hear  of  KaiFaba,  Gago,  and  other  Negro  countries  j.  but 
without  any  diftindt  notices  of  pofition  ;  and  beyond  ihefe  Melli. 

Kaffina  and  Bornou,  two  great  empires  on  the  north  of  the  river,  appear  to  divide  the 
largeft  portion  of  the  remaining  fpace  to  the  borders  of  Nubia  ;  and  extend  a  great  way 
to  the  north  ;  this  region  being  compofed  of  defert  and  habitable  country  intermixed  ;  but 
perhaps  containing  the  largeft  proportion  of  the  latter.  In  both  thefe  empires,  the  fove- 
reigns  are  Mahomedans,  but  the  bulk  of  their  fubjefts  are  faid  to  adhere  to  their  ancient 
worftiip;  that  is  to  fay,  the  lower  orders  arc  almoft  univerfally  Negroes  f. 

From  what  has  appeared,  perhaps  the  boundary  of  Nigritia  as  it  refpeds  the  Negro  popu- 
lation may  be  exprefled  generally,  and  with  a  few  exceptions,  as  follows  r  beginning  from  the 
weft,  the  extent  upwards  of  the  navigable  courfe  of  the  Senegal  river,  generally  — thence  a. 
line  drawn  to  Silla  ;  from  Silla  to  Tombudfoo,  Houfla,  and  BeriflTa,  along  the  river  Niger^ 
and  thence  through  Afouda,  Kanem,  and  Kuku,  to  Dongola  on  the  Nile. 

\jio%  enumerates  I2  ftates  or  kingdoms  of  Nigritia  :  but  amongft  thefe  he  includes 
Gualata,  a  trail  only  300  miles  S.  of  the  river  Nun  :  as  alfo  Cano  (Ganat),  adjacent  tO« 
Fezzan  ;  and  Nubia.    Kaifina,  Bornou,  and  Tombudoo,  are  included  of  courfe  §.. 

The  kingdom  of  the  Foulahs,  before  mentioned,  fituated  between  the  upper  part  of  the 
Gambia  river  and  the  coaft  of  Serra  Leona,  and  along  the  Rio  Grande,,  has  alfo  a  Maho- 

•  The  emperor  of  Morocco  is  faid  to  have  held  at  one  period  the  fovereignty  of  fome  of  the  countries  on  the 
northern  banks  of  the  Senegal  and  Niger  rivers.    Labat,  vol.  iii.  p.  339,  fpeaksof  incurfions  made  by  his  troops^ 
•{■  African  Affoc.  Q;_p.  126.  O.  p.  191. 

X  Page  4- 

§  The  Arabs  and  Mc.ort  call  Nigritia  by  the  general  name  of  Soudan.  By  Belad  Soudan,  or  the  country  of 
Soudan,  Abulfeda  includes  all  the  known  part  of  Africa,  fouih  of  the  Great  Defert  and  Egypt.  With  him 
Soudan  is  the  fouthern  quarter  of  the  globe.  D'Herbclot  alfo  allows  it  a  wide  range.  Atfnoo  is  anothel 
term  for  Nigritia,  in  ufe  atnong  the  natives  themfelves.  (See  alfo  Proceedings  Afric.  AJToc.  Q;_p.  164. 
O.  p.  i^fc) 

medaa 


Phyjfcal  and  Political  Geography  of  N'ortb  j^frlca.  25,^ 

medan  fovercign,  but  the  bulk  of  the  people  appear  to  be  of  the  ancient  religion.  It  has  been 
already  faid,  that  although  they  are  a  black  people,  they  are  lefs  black  than  the  Negroes  gene- 
rally, and  have  neither  crifped  hair  nor  thick  lips ;  as  alfo  that  they  have  a  language  diftinft 
from  the  Mandinga.  From  thefe  circumflances,  added  to  that  of  fuualion,  they  appear 
clearly  to  be  the  Leucathiopes  of  Ptolemy  and  Pliny.  The  former  places  them  in  the 
(Itiiation  occupied  by  the  Foulahs  ;  that  is,  in  the  parallel  of  nine  degrees  north;  havinotto 
the  north  the  mountains  of  Ryjfadius,  which  feparate  the  courfes  of  the  Stachir  and  Nia 
rivers  (Gambia  and  Rio  Grande),  and  which  therefore  anfwer  to  the  continuation  of  the 
great  belt  of  high  land  in  our  geography  ;  in  which  there  is  moreover  another  point  of  agree- 
ment, the  Caphas  of  Ptolemy  being  the  Caftaba  of  the  map  *. 

Ptolemy  by  the  name  evidently  meant  to  defcribe  a  people  Iffs  black  than  the  generality  of 
the  Ethiopians;  and  hence  it  may  be  gathered  that  this  nation  had  been  traded  with,  and 
that  fome  notices  refpefting  it  had  been  communicated  to  him.  It  may  alfo  be  remarked, 
that  the  navigation  of  Hanno  terminated  on  this  coaft  ;  probably  at  Sherbro'  river,  or 
found.  And  as  this  was  alfo  the  term  of  the  knowledge  of  Ptolemy,  it  may  be  juftly  fuf. 
pefted  that  this  part  of  the  coaft  was  defcribed  from  Carthaginian  materials  f . 

Thofe  who  have  perufed  the  Journal  of  Meflrs.  Watt  and  Winterbottom,  through  the 
Foulah  country  in  1794,  and  recoiled  how  flattering  a  pidure  they  give  of  the  urbanity 
ahd  hofpitality  of  the  Foulahs,  will  be  gratified  on  finding  that  this  nation  was  known  and 
diftinguifhod  from  the  reft  of  the  Ethiopians  at  a  remote  period  of  antiquity  |. 

The  contraft  between  the  Moorifti  and  Negro  charafters  is  as  great  as  that  between  the 
nature  of  their  refpeflive  countries  ;  or  between  their  form  and  complexion.  The  Moors 
appear  to  poffefs  the  vices  of  the  Arabs  without  their  virtues ;  and  to  avail  themfelves  of  an 
intolerant  religion,  to  opprefs  ftrangers :  whilft  the  Negroes,  and  efpecially  the  Mandingas, 
unable  to  comprehend  a  do£trine  that  fubftitutes  opinion  or  belief  for  the  focial  duties,  are 
content  to  remain  in  their  humble  ftate  of  ignorance.  The  hofpitality  fliewn  by  thefe  good 
people  to  Mr.  Park,  a  deftitute  and  forlorn  ftranger,  raifes  them  very  high  in  the  fcale  of 
humanity :  and  I  know  of  no  fitter  title  to  confer  on  them  than  that  of  the  Hindoos  of 
Africa:  at  the  fame  time  by  no  means  intending  to  degrade  the  Mahomedans  of  India  by  a 
comparifon  with  the  African  Moors. 


• ' 


*  The  Soluentii  of  Ptolemy  may  alfo  be  meant  for  the  Solimani  of  Mr.  Park. 

■f  And  it  may  alfo  have  been  the  fcene  of  traffic  mentioned  in  page  155  ;  as  Dr.  Wadftrom  fpeaks  of  fuch  a 
cuftom  in  this  quarter  at  the  prefent  day. 

J  Pliny  (lib.  v.  c.  S.)  alfo  fpeaks  of  the  Leucaethiopes,  but  feems  to  place  them  on  this  fide  of  Nigritia.   M«y 
it  a«t  be  that  certain  tribet  of  Foulahi  were  then  eftablilhed,  as  at  prefent,  along  the  Senegal  river  ? 


h\i  lY.  Ohfer. 


9.6c  On  the  Orlg'iH  of  Moniy, 


IV. 


Obfervatlcns  on  Metallic  Money  \  chlejly  tiireiied  to  nfctrtain  the  moji  adv^intageous  Dljirlhutlm 
and  Figure  of  Gold,  Silver,  and  Copper  in  Coins, 


I 


F  the  value  of  fcience  be  meafured  by  its  utility,  there  is  no  part  of  human  knowledge 
that  will  rank  higher  than  political  economy.  If  we  juiHy  applaud  the  inventor,  who  by 
the  conftruftion  of  a  machine,  or  the  improvement  of  a  chemical  procefs,  has  added  to  the 
fum  of  our  enjoyments,  in  onefmsU  part  of  the  great  fcheme  of  fecial  life;  how  much  more 
is  due  to  thofe,  who,  by  inveftigating  the  procefies  upon  which  that  fcheme  itfelf  depends, 
have  added  to  the  facilities  of  mutual  intercourfe,  and  given  vigour  to  every  department  cf 
adive  induftry? 

When  we  contemplate  the  ftate  of  man,  fupported  merely  by  the  art  of  the  hunter,  or  by 
the  immediate  produiSls  of  the  earth  ;  aflbciated  lefs  for  the  purpofe  of  mutual  affiftance  in 
the  arts  than  for  predatory  enterprife  or  djreft  refiftance  againft  the  bppreffion  ofhws  neigh- 
brturs;  we  are  almoft  inclined  to  think  him  of  a  different  fpecies  from  the  fame  creature 
in  the  civilized  ftate.  Upon  examination,  however,  it  appears,  that  the  inevitable  neceffity 
of  events  has  produced  the  difference.  The  variety  of  productions,  of  wants  and  of  fabrica- 
tions, has  given  rife  to  barter  or  exchange.  Mutual  fupply  has  increafed  the  fubJivifion.of 
labour,  and  improved  the  means  of  conveyance.  Streams,  roads,  fhips  and  carriages,  have  ex- 
tended this  beneficial  intercourfe.  Confidence  between  man  and  man  has  advanced  the  moral 
principles  of  fociety,  and  afforded  a  progreffion,  of  which  the  part  gradations  may  indeed  be 
traced,  but  to  the  future  part  of  which  the  imagination  can  fcarccly  afford  a  probable  outline. 

Among  the  impediments  to  commerce,  the  greateft  undoubtedly  is  the  charge  of  convey- 
ance from  place  to  place.  This  is  the  great  obftacle  which  limits  the  exchange  of  com- 
modities from  one  extremity  of  the  world  to  the  other.  Whenever  the  charges  of  carriage 
arife  to  fuch  an  amount  as  to  equal  the  effe£l:ual  return  in  any  remote  market,  the  motive 
for  conveying  merchandize  to  that  place  ceafes.  If  goods  were  always  exchanged  for  goods,, 
it  is  clear  that  the  conveyance,  under  the  uncertainty  of  difpofal,  would  take  place  to  a  very 
fmall  diftance  indeed ;  and  the  labour  required  to  difcover  the  perfons  willing  to  exchange 
would  greatly  enhance  the  charge.  It  would  require  a  volume  to  enumerate  and  defcribe 
the  expedients,  moral  as  well  as  mechanical,  by  which  thefe  difficulties  are  in  part  fubdued, 
and  ftill  more  to  deduce  their  origin  and  general  effeils.  One  of  the  chief  of  thefe  expedi- 
ents confifls  in  the  ufe  of  fome  article  of  merchandize,  as  the  medium  of  exchange,  which 
fhall  be  acceptable  to  every  man,  and  will  therefore  be  received  and  held  by  the  feller  of  any 
commodity  until  he  fliall  meet  with  another  individual,  who  he  knows  will  again  take  it  for 
the  article  he  wants. 

In  the  ifland  of  Madagafcar,  it  is  faid,  that  the  exchangeable  value  of  goods  is  reckoned  in 
hatchets,  bullock?,  and  flaves ;  thefe  commodities  being  univerfaliy  vendible,  and  for  that 
reafoa  every  where  received.  Smith  affirms,  that  nails  anfwer  the  fame  purpofe  in  fome 
parts  of  Great  Britain.  Thefe  and  other  inftanccs  may  ferve  to  fhew  how  a  preferable 
medium  of  exchange  becomes  adopted,  and  it  will  without  difficulty  be  feen  that  the  fcarceft 
and  leaft  deflruftiblc  metals  muft  have  at  length  become  the  univetfal  fubflitutes.  For  their 
value  does  not  depend  on  their  figure  3  they  may  be  fubdivided  and  joined  again  without 

6  lofs; 


If^at  Metal)  are  htfl  atlapUd  f(ir  t«!n,  ifyi 

lofs ;  they  receive  no  injury  by  keeping  -,  and  the  labour  of  conveying  them  from  place  to 
place  forms  a  lefs  part  of  their  value  than  of  almoft  every  other  article. 

The  firft  moneys  were  mere  quantities  of  metal  afcertained  by  weight,  as  the 
names  of  mofl  fpecies  ftill  indicate.  The  interference  of  governments  was  found  ne- 
ceflary  to  aflure  the  weight,  and  more  particularly  the  finenefs  of  determinate  portions  of 
metal ;  and  this  has  given  rife  to  an  opinion,  that  a  part  of  the  value  of  coin  muft  depend 
on  the  edi£t  of  the  State  which  iffues  it.  Whether  ftatefmcn  themfelves  have  in  reality 
thought  this  to  be  the  cafe,  is  little  to  the  purpofe  ;  but  it  is  certain  that  they  have,  from 
time  to  time,  yielded  to  the  temptation  of  diminifliing  the  quantity  of  precious  metal  ifflied 
under  a  given  denomination,  eitlier  by  openly  deducing  from  the  weight,  or  fecretly  de- 
bafing  the  coin  *.  Tranfadtions  of  this  nature  muft  have  operated  to  the  lofs  of  all  the 
creditors  in  the  State  ;  but  they  have  never  deceived  the  fellers,  who  have  always  regulated 
their  prices  by  their  knowledge  of  the  real  quantities  of  the  metal,  and  not  by  the  denomi- 
.nation  or  the  fuppofed  weight  or  finenefs  it  might  denote.  The  imaginary  coin,  or  money , 
of  account,  to  be  found  in  the  mercantile  books  of  almoft  every  commercial  nation,  mull 
have  arifen  partly  from  this  caufe. 

I  was  led  to  the  prefent  examination  by  hearing  that  a  committee  of  the  Royal  Academy 
has  been  appointed  to  take  into  confideration  a  proper  defign  for  a  new  coinage ;  and,  upon 
enquiry,  I  find  that  his  Majefty's  Privy  Council  have  repeatedly  deliberated  on  this  fubjeft, 
and  referred  the  ornamental  part  to  the  Royal  Academy  for  their  difcuflion  and  report. 
On  fuch  occafions  it  has  always,  and,  I  think,  rightly,  been  confidered  as  a  becoming  tranf- 
aflion  on  the  part  of  individuals  to  give  their  thoughts  to  the  world  by  the  medium  of  the 
prefs  ;  and  under  this  convidion  it  is  that  I  have  ventured  to  place  tie  fubjeft  in  the  light . 
it  appears  to  me  to  require. 

The  metals  ufed  for  coinage  are  gold,  filver  and  copper.  According  to  the  exchange- 
able value  of  gold,  half  a  grain  of  this  metal  would  purchafe  as  much  bread  as  a  man  could 
eat  at  one  meal.  This  fmall  piece  of  gold,  if  as  thin  as  paper,  would  not  meafure  above 
the  tenth  part  of  an  inch  in  breadth,  and  would  therefore  be  perfectly  inconvenient  for 
ufe.  It  has,  in  faft,  been  found,  that  the  gold  coin  of  the  weight  of  32  grains  (or  the 
quarter  guinea)  was  too  fmall  to  be  conveniently  ufed.  The  fame  obfervations  will  apply 
to  the  fmaller  fub-divifions  of  the  fliilling  of  filver ;  whence  upon  the  whole  it  appears, 
that  coins  of  all  the  three  metals  are  required  to  facilitate  our  commerce  of  buying  and 
felling. 

Gold,  filver  and  copper,  like  every  other  produce  of  human  induftry,  depend  for  their 
value  principally  on  the  labour  employed  in  producing  and  bringing  them  to  market,  and 

•  This  diminution  has  taken  place  throughout  Europe.  With  us  the  pound  of  money,  which  about  the 
ytar  1087  contained  3.  pound  weight  of  filver,  hss  continued  at  lefs  than  one-third  (or  ^°)  of  that  quantity 
ever  fmce  the  reign  of  Elizabeth.  Our  neighbours  however  have  univerfally  exceeded  us  in  this  rcfpcft.  Thus 
the  pound  Flemilh  is  lefb  than  eleven  ftiillings  ;  the  French  livre  is  ten  pence,  and  the  Italian  Jire  is  lefs 
than  i{d. 

The  Chinefe  ftill  ufe  fine  filver,  which  they  adlually  cut  and  weigh  at  every  fingle  payment.  They  are  faid 
to  have  formerly  poffeffed  filver  coin  ;  but  whether  they  were  urged  to  their  prefent  praflicc  by  uncertain  va- 
ri«£Jons  in  its  value  caufedby  their  rulcrt,  or  by  the  difficulty  of  otherwife  refilling  the  artifices  of  coiners,  I 
{(now  not. 

io 


a62  The  Operations  of  Gold  and  Silwr  as  jixtd  Coin:, 

in  a  confulcrable  degree  upqiv  tfi£  aA-ual  demand.  As  thefe  articles  are  not  employed 
merely  in  the  fabricatlgii  of  jCQinj,  the  d^^niand  will  vary  in  each  according  to  circum- 
llaiices,  whicluadmit;  of  jio  permanent  ratio,  of  exchange  between  them.  If  the  State  were 
to  coin  certain  pieces  of  known  weight  and  finenefs  out  of  each  of  thefe  metals,  and  de- 
termine that  a  certain  number  of  the  filver  pieces,  for  example,  (hould  in  all  cafes  be 
equivalent  to  one  piece  of  the  gold,  it  would  naturally  follow,  fuppofing  the  individual  to 
pay  nothing  for  the  coinage,  that  a  debt  might  be  difcharged  with  mod  facility  to  the 
debtor,  and  confjquently  lof§  to  the  creditor,  in  the  cheapefl  of  thefe  two  metals,  whenever 
by  the  fluctuation  of  the  market  either  of  them  (hould  come  to  reprefent  a  larger  portion 
of  the  other  than  the  edi61:  of  the  government  had  determined.  This  confequence  of  fix- 
ing the  relative  value  of  coins  would  fhow  itfelf  in  a  variety  of  wjys,  which  need  not  be 
enumerated  ;  becaufe  it  is  certain  that  the  dearer  metal  would  occupy  the  greater  part  of 
the  circulation,  while  the  cheaper  pieces  would  either  be  melted  down  or  diminiflied,  if 
their  rated  value  were  too  high,  or  they  would  be  fabricated  by  individuals  if  it  were  too 
low,  in  defiance  of  every  public  regulation  which  might  be  adopted.  If  we  therefore  ad- 
mit, from  confideratlons  of  this  nature,  that  no  government  does  in  reality  poffefs  the  means 
of  fixing  a  ratio  between  two  articles  of  commerce,  intended  to  be  applied  as  the  tickets 
of  transfer  or  mediums  of  exchange,  we  fliall  be  naturally  led  to  the  adoption  of  one  of  the 
metals  only,  as  the  reprefentative  fign,  while  the  two  others  are  applied  merely  as  inftru- 
ments  of  accommodation  for  the  convenient  fub-dlvifions  of  value. 

With  regard  to  the  queftion  of  preference  in  thefe  three  metals,  experience  has  fliewn 
that  fociety  is  difpofed  to  afiume  the  dearefl: ;  namely,  gold.  With  a  fiiigle  ftandard  of 
value,  the  flu£luations  of  the  market  price  of  the  metal,  when  compared  with  other  com- 
modities, will  be  nearly  imperceptible,  becaufe  they  confound  themfelves  with  the  rife 
and  fall  in  the  prices  of  all  other  articles  to  which  the  ftandard  is  thus  applied.  If  a 
cheaper  metal  were  to  be  adopted  by  the  State,  and  gold  were  left  to  circulate  at  the  elec- 
tion of  individuals,  the  changes  of  price  in  this  metal  of  high  value  would  operate  fo  as 
to  produce  an  uncertainty  in  the  amount  of  large  fums,  and  greatly  dUturb  the  general 
tranfaftions  of  commerce.  Merchants  would  therefore  confider  the  gold  coinage  as  mere 
bullion,  and  the  community  would  in  a  great  meafure  be  deprived  of  its  ufe  as  a  coin  ;  as 
is  aftually  the  cafe  in  Holland  and  other  countries  where Yilver  is  the  legal  medium*.  Hence 
it  appears  moft  eligible,  that  gold  in  pieces  of  determinate  weight  and  finenefs  fliould  con- 
ftitute  the  efFe£live  coin  of  the  State,  or  legal  tender  of  payment ;  that  filver  and  copper 
(hould  be  formed  into  money  for  the  purpofe  of  reprefenting  fraftions  of  the  fmallefl  gold 
coin  }  and  that  the  creditor  or  feller  fhould  have  the  option  to  refufe  all  payments  in  thefe 
laft  metals  for  any  fum  exceeding  the  fmalleft  unity  of  the  gold  coin. 

By  this  diftribution,  though  the  coins  of  filver  and  copper  would  in  flri£tnefs  be  fubjedl 
to  fludluations  arifing  from  the  flate  of  the  market  with  regard  to  thofe  metals,  yet  thcdif- 

•  A  ftill  more  dcfeftive  fcheme  was  propofed  in  the  Report  presented  by  Prieur,  de  la  C4te  d'Or,  frdm  a  Com- 
mittee of  the  Council  of  Five  Hundred,  of  which  a  very  full  abftraft  is  given  in  thcMoniteursof  6and  7Floreal 
in  the  year  VI.  Nos.  ii6,  217.  It  is,  that  filver  coin  fliould  be  unchangeable  in  weight  and  denomination  of 
Talue ;  but  that  the  price  of  gold  (alfo  coineti)  fliould  be  fettled  every  fix  months  by  a  declaration  firom  the  Na- 
tional Treafury,  deduced  from  the  medium  price  of  that  metal  during  the  preceding  half-year.  It  was  rejeft- 
ed  by  the  Council  of  Ancients, 

fcrcnce 


Relative  Valuet^  IVear^  Alloy^  Figure-^  (sc.  of  Coin.  263 

ference  would  be  difrcgarded  in  the  difcharge  of  accounts,  hecaufe  it  could  never  amount 
to  a  fum  of  any  importance.  The  only  inconvenience  which  offers  itfeif  under  fuch  an 
iirrangement  is,  that  thefe  fubordinate  coins  would  alfo  be  melted  and  fold  when  the  metal 
was  dear,  or  they  would  be  fabricated  if  the  metal  ever  happened  to  be  fo  cheap  as  to  afford 
an  adequate  motive  of  profit  to  the  illegal  coiner.  The  State,  in  its  deliberations  on  this 
fubjeft,  might  determine  that  the  coins  of  filver  and  copper  Ihould  pafs  either  for  lefs 
than  the  medium  market  price  of  the  metal,  or  for  more,  or  for  that  value  precifely.  It  is 
eviilent  that  the  firfl  of  thefe  difpolitions  would  afford  coin  which  would  continually  vanifli 
in  the  melting-pot,  and  is  therefore  altogether  unadvifable.  The  medium  rate  of  intrinfic 
value  would  produce  a  fimilar  efFeft  whenever  the  market  price  was  low.  Whence  it  fol- 
lows, that  the  metal  contained  in  fuch  auxiliary  money  ought  to  be  of  lefs  value  than  the 
gold  it  reprefents  ;  and  to  prevent  the  introdudion  of  a  fimilar  coinage  from  private  manu- 
fa£lurcrF,  it  would  be  neceffiiry  that  the  difference  between  the  value  of  the  metal  and  that 
reprefented  by  the  coin  fliould  be  fomewhdt  lefs  than  the  coft  of  workmanfhip.  Under 
thefe  circumftances  the  public  would  be  fuppjied  with  an  ufeful  implement  or  ticket  of 
exchange,  which  would  operate  as  a  pledge  of  value,  very  nearly  to  the  amount  of  its  de- 
nomination, and  would  be  afforded  cheaper  from  the  extenfive  manufaftories  of  govern- 
ment than  it  could  poffibly  be  made  by  private  workmen. 

Coin,  like  every  other  utenfil  or  tool,  is  fubje£t  to  wear,  and  will  in  procefs  of  time  be 
more  or  lefs  deprived  of  its  diflindlive  figure,  and  rendered  lefs  valuable  by  the  lofs  of 
freight.  When  new,  it  is  the  real  pledge  or  meafure  it  pre! ends  to  be  ;  but,  if  it  be  fuftered 
to  circulate  after  its  weight  is  confiderably  diminlfhed,  it  may  become  a  defirable  obje£l  to 
the  coiner  to  fabricate  pieces  apparently  in  the  worn  (late,  or  otherwife  he  may  exercife 
his  induftry  in  fpeedily  reducing  the  new  coin  to  that  (late,  for  the  fake  of  the  precioua 
metal  he  may  thus  acquire. 

If,  on  the  contrary,  the  Legiflature  fhould  forbid  the  currency  of  pieces  worn  beyond  a 
certain  fmall  or  moderate  lofs,  the  confequence  will  be,  that  all  fuch  pieces  will  return  to 
the  Mint  to  be  recoined  ;  and  the  charge  of  coinage  may  become  fo  heavy  as  to  abforb  a 
confiderable  part  of  the  value  of  the  whole  circulating  medium  in  the  courfe  of  a  few 
years. 

To  diminilh  this  laft  inconvenience  as  much  as  poffiblc,  it  becomes  ueceflary  to:  attend 
to  the  nature  of  the  metal  as  well  as  to  the  figure  of  the  piece.  Whether  the  Dutch  ducat, 
of  fine  gold,  or  the  Englifh  guinea,  of  twenty-two  carats,  may,  under  like  circumftances,  be 
moft  difpofed  to  lofe  by  wear,  has  not  I  believe  been  determined  ;  but  it  feems  to  be  ge» 
nerally  underftood,  that  our  (landard  gold  in  watch-cafes  and  other  trinkets  is  lefs  durable 
than  the  coarfer  and  harder  gold  allowed  to  be  wrought  in  France  and  Geneva^  If  this 
be  true,  ii  (lionld  feem  as  if  there  exided  no  motive  for  raifing  the  (landard  of  our  gold, 
and  perhaps  the  fame  argument  may  apply  (till  more  to  our  filver  :  and  the  advantage,  if 
any,  in  lowering  the  (landard  without  dimiiu(h  ng  the  intrinfic  value,  has  not  yet  beea 
fliewn  with  fufficient  evidence  to  juflify  the  offence  againd  edablifhed  ufe  and  public  pre- 
judice which  fuch  a  proceeding  might  afford.  Admitting  thefe  obfervations  to  be  con- 
clufive  againft  altering  the  (landard,  it  would  follow,  that  the  greater  durability  of  cpia- 
mud  be  fought  for  in  its  figure. 

Let  tts  imagine  a  coin  to  pofTefs  the  figure  of  an  equilateral  triangle  5  let  it  be  tliin,  in. 

cxdez 


2<54.  Effl'ifs  of  the  Figure^  Indentation,  Relief,  i^e,  of  Metaltic  Money. 

order  that  it  may  prefent  a  large  furface  j  let  its  edges  have  the  figure  of  a  faw,  and  its  face* 
that  of  a  file.  Under  thefe  conditions  we  (hould  fabricate  one  of  the  ■worft  or  Icaft  durable 
coins  that  could  be  chofen.  For  the  angles  would  be  eafily  broken  and  worn,  and  the  edges 
and  faces  would  mutually  operate  on  each  other,  with  a  degree  of  rapidity  which,  it  may  b^ 
concluded,  would  very  foon  take  away  all  the  (harp  prominences,  and  greatly  diminilh  the 
weight.  On  the  other  hatid,  let  us  fuppofe  the  leafl  polhble  furface,  and  wc  fhall  obtain 
the  fpheiical  figure  *.  AgainR  this  it  appears  to  be  an  obje£\,ion,  that  if  it  be  nearly  per- 
fect, the  impreflions  dillinclive  of  its  purity  and  denomination  mud  be  indented,  and  will 
not  herefore  fufliciently  limit  its  apparent  magnitude  ;  and  if  they  be  prominent  it  will 
no  longer  ibe  a  fphere,  but  a  figure  prefenting  fharp  angular  parts  with  fmall  bearings  very 
liable  to  deftruftion. — What  then  is  the  figure  which  fliall  partake  fo  much  of  the  plane, 
as  to  prefent  furfaces  of  broad  contadt  or  bearing,  and  afford  the  leaft  quantity  nf  angular 
prominence  ?  It  is  evidently  the  cylinder:  and  this  is  the  figure  mod  generally  adopted  for 
money.  The  edge  of  tlse  cylinder  affords  the  fmallefl  bearing.  It  mud  therefore  be  veiy 
fliort  or  fiat,  in  order  that  the  weight  of  the  piece  may  be  difpofed  to  reft  on  the  bafe,  and 
not  on  the  edge. 

If  the  whole  furface  of  a  piece  of  metal  were  covered  with  figures  or  imprefflons,  it 
would  be  immediately  feen  whether  any  part  had  been  abraded  by  accident  or  defign.  If 
the  impreffions  were  concave,  they  might  eafily  be  renewed  by  the  punch  or  the  graver  ; 
but  if  they  were  in  relief,  it  would  be  almoft  impolTible  to  reftore  them  when  once  worii 
or  obliterated.  For  this  reafon,  the  preference  in  coinage  has  moftly  been  given  to  figures 
in  relief. 

It  is  however  a  very  ferlous  Inconvenience,  that  when  the  diftin£live  marks  are  thus  ren- 
dered prominent,  the  face  of  the  coin  no  longer  fuftains  the  preflure  and  wear  of  the  piece  ; 
but  the  marks  themfelves  are  made  to  fupport  the  whole.  Thus,  in  our  gold  money,  par- 
ticularly of  the  laft  recoinage,  the  edge  is  a  faw,  and  the  numerous  minute  prominencies 
on  the  face  conftitutc  a  file,  the  operations  of  both  which  are  feverely  felt  in  the  rapid 
deftru^tlon  of  the  piece  \. 

Hence  we  may  obferve,  that  neither  kind  of  mark  alone  is  fuited  to  a  coin  intended  to 
poflefs  durability,  and  at  the  fame  time  to  be  difficult  either  to  imitate  or  diminilh,     A  com  , 

•  The  pagoda  ancl  fanam  of  India  are  the  only  coins  I  recolleft  which  approach  towards  this  figure. 

f  To  place  this  in  a  more  ftriking  light,  it  may  be  obfcrved  that  the  amount  of  gold  coined  between  tl>e 
years  1764  and  1772.  both  incluGve,  v.  as  8,  ,203  1.  15s.  6  d.  and  between  1782  and  1792,  boih  inciufivc,  was 
19,675,6661.  14s.  6d,  and  between  1773  and  1777,  both  inclufive,  was  10,1591,833  1.  i  s.  During  the  middle 
period  laft  mentioned  the  great  recoinage  of  gold  took  place.  I  am  aware  that  other  caufcs  may  have  cccafioned 
a  demand  for  coin  bcfides  the  mere  wear  of  the  old  pieces,  and  that  the  increafeof  commerce  and  maniifaflures 
has  in  faft  produced  luch  a  demand ;  but  as  this  laft  event  (diftinguifliable  by  its  gradual  progrefs)  does  not  ajj- 
pear,  from  the  numbers  in  the  account,  to  have  influenced  the  coinage  in  any  great  proportion,  I  ihall  difregard 
it  in  the  pfcfent  rough  ftateraent  With  this  liberty,  we  may  proceed  to  remark,  ift.  That  as  moft  of  the  old 
pieces  ilifappeared  during  the  middle  term  of  time  the  number  of  nineteen,  or  fay  twenty  millions  muft  nearly  re- 
prefcnt  the  whole  of  our  gold  money.  2d.  That  the  national  lofs  by  wear  in  the  firft  period,  when  the  gold  was 
,.cld  and  fmooch,  reckoned  at  '  per  cent,  on  the  fum  recoined,  was  3708  1.  per  annum  ;  and  in  the  latter  period 
S943I.  per  annum:  and  3d.  That  the  whole  national  ftock  of  gold  coin,  under  the  regulations  and  figure  of 
the  laft  period,  wests  out  and  is  recoined  every  eleven  'years.  The  account  of  coinage  is  to  be  found  in  the 
Report  (^,Ae  fords'  Ctmmittee-of  Secrecy,  primed  April  »8,  1797. 

'  '     ■     ■  ■  ■  biuatioa 


Figure  of  tnctailic  Money.— ^Bleaching  of  Imprejfions  frem  Engravings.  "46^ 

binatlon  of  both  methods  is  neceff<iry.  If  a  coin  be  ftrucic  with  indentations  or  parts  de» 
prefTed  beneath  the  common  furface,  and  in  thefe  there  be  prominent  objefts  or  defigns,  not 
more  eievated  than  that  furfa-ce,  the  general  advantage,  with  regard  to  wear,  will  approach 
towards  that  of  the  plain  furface  itfelf,  and  the  impreffion  will  be  at  Icafl:  as  difficult  to  imitate, 
if  not  more  fo  than  that  of  a  defign  rifing  totally  above  the  common  (lirface  *.  The  late 
copper  coinage  of  pieces  of  one  and  of  two  pennies  are  of  this  kindf. 

To  fum  up  the  foregoing  conclufioiVs  i/i  a  few  words,  we  may  remark,  that,  i.  The  State 
is  unable  (from  the  natural  impradticability  of  the  thing)  to  appoint  two  dirtinct  articles  of 
commerce  as  the  circulating  mediums  of  exchange.  2.  The  meafure  of  value  or  legal  tender 
•ought  to  confift  in  the  metal  which  bears  the  higheft,  price,  namdy,  gold.  3.  Coin  of  filver 
and  copper  are  required  for  fmaller  fradiions  than  the  actual  fubdivifions  of  the  gold  coin,  but 
fliould  be  optional  in  the  receipt  for  any  larger  fums.    4.  Thefe  laft-mentioned  coins  ought 

xto  reprefent  a  value  in  gold  equal  to  their  own  quantity  of  metal,  at  the  higheft  (or  perhaps 
medium)  market  price  added  to  the  charge  of  fabrication.  5.  No  fufficient  reafon  has  yet 
been  given,  to  fjiew  tliat  the  ftandard  of  gold  coin  fliould  be  changed  in  order  to  render  it 
more  durable.    6,  The  beft  figure  of  coin  is  a  ftiort  cylinder  or  flat  round  plate  ;  and  7.  The 

ciiftindive  marks  or  impreffions  (hould  be  made  neither  altogether  hollow  nor  altogether  in 
relief,  but  by  a  combination  of  both  form?,  fo  as  to  leave  a  flat  bearing  furface  on  each 
fide. 


V. 

An  eafy  Method  of  cleaning  and  bleaching  Copper-Plate  Imprejfions  or  Prints.  ExtraEled  from  a 
Letter  of  Sig.  Gio.  FabbrONI,  SubdireSfor  and  Superiniendant  of  the  Royal  Cabinet  of 
Philofophy  and  Natural  Hijlory  of  -jjis  Royal  Highnefs  the  Grand  Duke  of  Tufcany,  to  Sig, 
D.  LUICI  TaSGIONI  at  Naples  %. 

Q 

O  I  N  C  E  the  happy  invention  of  engraving  in  copper,  which  no  doubt  owes  its  origin  to 
the  revival  of  the  art  of  chafing  and  ornamenting  plate,  colleilors  have  availed  themfelves  of 
this  means  to  accumulate  and  preferve  copies  of  the  moft  valuable  pi6l:ures  and  drawings. 
This  objeiSl  of  refearch  becomes  every  day  more  prevalent,  and  prints  of  the  early  and  moft 
celebrated  mafters  are  now  fought  for  with  the  utmoft  avidity. 

Ancient  prints  are  valuable,  not  only  for  their  own  intrinfic  merits,  but  as  monuments  of 

*  Few  coins  have  been  made  of  this  figure.  The  Chinefe  coin  of  mixed  copper  called  the  ca(h  is  the  moft 
Temarkable,  and  perhaps  the  only  one  of  extcnfive  circulation. 

t  Of  copper,  by  M.  Boulton,  Efq.  for  Government,  The  penny  is  rather  more  than  1.4  inch  in  diameter, 
ind  about  o.t  j  inch  thick  at  the  edge,  and  weighs  1  oz.  avoirdupois.  A  circular  part  of  the  face  on  each  fide 
rather  more  than  i.i  inch  in  diameter  is  depreffed  by  the  ftroke  of  the  dye,  in  one  of  which  is  feen  the  hebd  of 
the  King  in  relief,  and  in  the  other  a  figure  of  Britannia.  Upon  the  prominent  rim  on  one  fide  are  the  words 
"  Georgius  III.  D.  G.  Rex,"  and  on  the  other  "  Britannia  1797"  in  funken  letters.  The  edgi:  or  cylindrical 
furface  is  plain.  The  two-penny  piece  refembles  the  penny;  but  its  diameter  is  1.4  inch  :  funk  face  1.45  inch, 
and  weight  z  oz,  avoirdupois  wanting  jo  grains  in  the  piece  before  me.  I  fuppofe  the  average  weight  to 
be  2  ounces. 

X  Trariflated  from  the  Italian.  Communicated  by  Andrew  Duncan,  jun.  M.  D.  of  Edinburgh,  who  re- 
ceived it  from  the  author.     The  original  is  inlertcd  in  the  Giornale  Letterario  di  NapoU,  No.  85.   "    * 

Vou  II — Sept.  1798.  M  m  the 


a66  Bleaching  of  Imprej^om  ft  an  Engravings, 

the  hirtory  of  the  art.  But  their  fcarcity  renders  them  flill  more  Valuable.  Moftofthofe 
which  arc  ftiil  extant  are  defaced  by  negligence,  during  the  time  of  their  remaining  fufpend- 
ed  a^aiaft  walls  cxpofed  to  fmolte,  vapor,  and  the  excrements  of  infeiSs,  Colle£lurs  of 
prints  have  not,  however,  (hewn  the  fame  partiality  as  antiquarians  for  the  patina;  but  on  the 
contrary  they  have  fought  and  praiitilcd  a  method  of  clearing  prints  from  thefc  impurities. 

This  method  conTdls  in  hmple  wafhing  with  clear  water,  or  a  ley  made  of  the  afhes  of 
vine  ftallcs  or  reeds,  and  laftly  by  a  long  expofure  to  the  dew.  Aqua  fortis  is  alfo  ufed  for 
the  fame  pnrpofe,  but  with  a  degree  of  rifque  at  lead  equal  to  its  advantages.  The  ley 
difn>!ves  not  only  the  impurities  but  likewife  the  oil  of  the  printing  ink,  and  either  difcharges 
it  totally,  or  leav  s  a  cloudy  appearance.  The  aqua  fortis  afts  on  the  vegetable  fibre,  of 
which  the  paper  itfelf  is  compofed,  and  produces  a  dark  colour,  which  cannot  be  removed 
by  means  of  this  liquid,  but  by  an  adlion  which  would  confiderably  injure  the  paper  itfelf. 

The  difcovery  of  Prieftley,  of  the  fluid  erroneoufly  named  by  him,  but  fuice  known  by 
the  name  of  oxygen ;  and  the  information  we  have  obtained  from  Scheelc,  of  the  effecis  of  its 
combination  with  muriatic  acid,  have  led  Berthollet  to  the  ufeful  application  of  its  properties 
to  the  a£t  of  bleaching  cloths,  Chaptal  to  that  of  bleaching  prints  and  books,  and  Giobert  to 
the  art  of  painting.  But  the  method  of  making  this  preparation  is  too  inconvenient  for  a 
mere  amateur  and  colledior  of  prints,  and  the  oxygenated  muriatic  acid  is  not  yet  to  be  pur- 
chafed  ready  prepared  in  Italy.  It  may  not,  therefore,  be  unacceptable  to  defcribe  an  eafy 
method  of  effeding  this  purpofe  without  the  difficulties  of  chemical  procefTes,  and  within 
the  ability  of  any  perfon  to  perform. 

It  is  known  that  oxygen  is  abundantly  contained  in  the  combinations  called  metallic  calceSy 
though  in  a  ftate  of  inaftivity  ;  and  it  is  equally  well  afcertained,  that  thefe  fubftances  have 
a  very  flrong  af.raftion  for  it.  On  the  other  hand  it  is  a  faft,  that  fome  of  the  metallic 
calces  of  very  moderate  price  are  capable  of  eafily  yielding  the  whole  or  the  greateft  pro- 
portion of  this  conftituent  part.  Manganefe  is  not  very  well  adapted  for  this  purpofe  ;  but 
minium  is  much  better.  Nothing  more  is  required  to  be  done,  but  to  provide  a  certain 
quantity  of  the  common  muriatic  acid,  for  example,  three  ounces,  in  a  glafs  bottle,  with  a 
ground-ftopper,  of  fuch  a  capacity  that  it  may  be  only  half  full.  Half  an  ounce  of  minium 
mufl  then  be  added ;  immediately  after  which  the  ftopper  is  to  be  put  in,  and  the  bottle  fet 
in  a  colJ  and  dark  place.  The  heat,  which  foon  becomes  perceptible,  fhews  the  beginning 
of  the  new  combination.  The  minium  abandons  the  greateft  part  of  its  oxygen  with  which 
the  flu  d  remains  impregnated,  at  the  fame  time  that  it  acquires  a  fine  golden  yellow,  and 
emits  the  deteftable  fmell  of  oxygenated  muriatic  acid.  It  contains  a  fmail  portion  of 
muriate  of  leud  ;  bu  this  is  not  at  all  noxious  in  the  fubfequent  procefs.  It  is  alfo  necelTary 
to  be  obferved,  that  the  boitie  muft  be  ftrongj  and  the  floppcr  not  too  firmly  fixed,  other- 
wife  the  aftive  eLflic  vapor  might  burfi  it.  The  method  of  ufing  this  prepared  acid  is  as 
follows : 

Provide  a  fufHciently  large  plate  of  glafs,  upon  which  one  or  more  prints  may  be  feparate- 
)y  fpread  out.  Near  the  ed  es  'ct  there  be  raifed  a  border  of  foft  white  wax  half  an  inch 
high,  adhering  well  to  the  glafs  and  flat  at  top.  In  this  kind  of  trough  the  print  is  to  be 
placed  in  a  bath  of  fre'fh  urine,  or  water  containing  a  fmall  quantity  of  ox  gall,  and  kept  in 
this  fituation  for  three  or  fuur  hours.  The  fluid  is  then  to  be  decanted  off,  and  pure  warm 
water  poured  on,  which  mull  be  changed  every  three  or  four  hours  uatii  it  pafTes  iimpid  and 

clear. 


Bleaching  of  Prhits.-^Cunous  FaSfs  refptP.ing  the  Zebra,  267 

clear.  The  impurities  are  fometimes  of  a  refinous  nature,  and  refift  the  aflion  of  pure 
water.  When  this  is  the  cafe  the  wafhed  print  muft  be  left  to  dry,  and  alcohol  is  then  to  be 
poured  on  and  left  for  a  time.  After  the  print  is  thus  cleaned,  and  al!  the  moifture  drained 
off,  the  muriatic  acid  prepared  with  minium  *  is  to  be  poured  on  in  fufficient  quantity  to 
cover  the  print ;  immediately  after  which  another  plate  of  glafs  is  to  be  laid  in  contaiEt  witfct 
the  rim  of  wax,  in  order  to  prevent  the  inconvenient  exhalation  of  the  oxygenated  acid.  la 
this  fituation  the  yelloweft  print  will  be  feen  to  recover  its  original  whitenefs  in  a  very  fhorC 
time.  One  or  two  hours  are  fufficient  to  produce  the  defired  effc£l ;  but  the  print  will  re- 
ceive no  injury  if  it  be  left  in  the  acid  for  a  whole  night.  Nothing  more  is  neceflary  to  com- 
plete the  work,  than  to  decant  off  the  remaining  acid,  and  wafh  away  every  trace  of  acidity 
by  repeated  affufions  of  pure  water.  The  print  being  then  left  to  dry  (in  the  fun  if  p;){nbL') 
will  be  found  white,  clear,  firm,  and  in  no  refpeil  damaged  either  in  the  texture  of  the  paper 
or  the  tone  and  appearance  of  the  impreHlon. 


A, 


VI.     . 

On  the  Propagation  of  the  Zebra  with  the  Afs  \, 


L.N  experiment  was  made  in  the  year  1773  with  a  zebra,  in  the  colle£lion  of  the  late 
Lord  Clive,  the  rcfult  of  which,  though  of  confiderable  intereil  to  the  natural  hiftorian,  is  no 
where  upon  record  in  any  public  journal  or  printed  work.  A  fet  of  queftions  were  propofed 
at  the  time  of  the  event  to  Mr  Parker  %  by  Sir  Jofeph  Banks  ;  which,  together  with  the 
anfwers,  he  has  at  my  requeft  permitted  me  to  make  ufe  of. 

The  zebra  was  firft  covered  by  an  Arabian  horfe.  For  this  purpofe  it  was  found  neceflary 
to  bind  her,  and  flie  {hewed  great  difgull.  As  flic  did  not  conceive,  an  Englifli  afs  was 
procured  ;  to  which  (he  (hewed  a  degree  of  averfion,  fcarcely  if  at  all  lefs  than  to  the  horfe, 
and  was  fubj"e£led  to  him  by  the  fame  means.  The  refult  of  this  trial  not  being  more 
favourable  than  the  other,  recourfe  was  had  to  the  extraordinary  expedient  of  painting 
another  afs  fo  as  to  refemb'e  the  zebra.  Complete  fuccefs  attended  this  deception. 
When  the  animals  were  put  together,  the  zebra  at  firft  appeared  (hy  ;  but  (he  received  the 
embraces  of  the  painted  aft,  and  conceived.  The  offspring  was  a  fine  large  male  foal, 
which  was  juft  turned  of  fix  months  old  at  the  time  of  enquiry,  namely,  December  1773.  It 
refembled  both  parents  ;  the  father  as  to  make,  and  the  mother  as  to  colour ;  but  the  colour 
was  not  fo  (trong,  and  the  ftripes  on  the  (lioulders  were  more  confpicuous  than  on  any  other 
p-art.  In  anfwer  to  a  queftion  dire£ted  to  that  objeft,  the  relator  ftates  it  as  his  opinion, 
that  it  would  very  probably  propagate  its  fpecies,  as  it  did  not  appear  at  all  like  a  mule. 

In  the  courfe  of  the  year  after  this  information  was  received,  his  lardftiip  died  fuddenly,  and 

■'*  As  I  have  not  repeated  t^'is  procefs,  I  cannot  cftimate  how  far  the  prefence  of  the  lead  may  weaken  the 
corrofive  aftion  of  the  acid  onthc  paper;  but  I  (liould  be  dilpofcd  to  recommend  a  previous  dilution  of  the  acid 
with  w.iter.  Whoever  ufes  this  procefs  will  of  courfe  make  himfelf  mafter  of  the  proportion  of  water  re- 
quired to  dilute  the  acid,  by  making  his  firft  trials  with  an  old  print  of  no  v^lue.     N. 

■+  Communicated  by  the  Right  Hon.  Sir  Jofeph  Banks,  Bart.  K.  B.   P.  R.  S.  i:c.  &c. 

J  He  was  either  Steward  or  in  fome  other  confidential  employ  to  Lord  Clive. 

M  m  2  the 


269  Jmpraved  Pncefs  of  Bleaching, 

the  coIlefVion  of  ariimats  was  difpofed  of.  Sir  Jofeph  Banks  wa's  then  abfent  from  town ;  and 
upon  his  return  he  was  prevented^  by  this  circumftiiice,  either  from  purchaiing  the  animals 
or  acquiring  any  further  information  refpeftinjj  the  foal.  I  have  lately  endeavoured  to  dbtaiit 
feme  intelligence  on  this  behalf  among  the  dealers  in  animals,  but  hitherto  without  fuccefs. 


VII. 


On  tht  Proems  sf  Bleacbiug  with  the  Oxygenated  Muriatic  Acid ;  and  a  Befcription  of  a  new 
Jjiparaiits  for  Bleaching  Cloths  with  that  Acid  dijjolved  in  Water  without  the  Addition  of- 

Alkali.    By  Theophjlvs  Lewis  Rupp*. 


T. 


II  E  arts  which  fupply  the  luxuries,  conveniences  and  necefTarles  of  life,  have  derived 
but  little  advantage  fiom  pliilofopheis.  A  view  of  the  hiftory  of  arts  will  evince  the  juftice 
of  this  obfervation.  In  uieclianics,  for  inftance,  we  find  that  the  moft  important  inventions 
and  improvements  have  been  made,  not  through  the  rcafonings  ofphilofophers,  but  through 
the  ingenuity  of  artifts,  and  not  unfrequently  by  common  workmen.  The  chemift  in  parti- 
cular, if  we  except  the  pharmaceutical  laboratory,  has  but  little  claim  on  the  arts  :  on  the 
contrary,  he  is  indebted  to  them  for  the  greateft  difcoverics,  aiKJ  a  prodigious  ?iumber  of  facb,. 
which  form  the  bafis  of  his  fcience.  In  the  difcovery  of  the  art  of  making  bread,  of  the 
vinous  and  acetous  fermentations,  of  tanning,  of  working  ores  and  metals,  of  making  glafs 
and  foap,  of  the  adlion  and  applications  of  manures,  and  in  numberlefs  other  difcovettes  of 
the  higheft  importance,  though  they  are  all  chemical  proceffes,  the  chemift  has  no  fhare. 
But  no  branch  of  the  ufeful  arts  is  lefs  indebted  to  him  than  that  of  changing  the  colours  of 
fubftances.  The  art  of  dyeing  has  attained  a  high  degree  of  perfection  without  the  aid  of 
the  chemift,  who  is  totally  Ignorant  of  the  rationale  of  many  of  its  procefl'es,  and  the  little  he 
knows  of  this  fubjedl:  is  of  a  late  date.  Tlie  proc.efs  of  dyeing  the  Turkey  red  has  beea  known 
and  pra£l:ifed  from  time  immemorial  by  the  moft  uncultivated  nations,  but  its  theory  is  not 
yet  underftood  by  philofophers.  The  manufacture  of  indigo  and  its  application  have  been 
long  known  to  the  planter  and  the  dyer  ;  but  it  is  not  more  than  ten  years  fince  a  true  theory 
of  them  has  been  formed.  The  art  of  printing  or  topical  dyeing  is  of  the  greateft  antiquity ; 
but  the  theory  of  this  procefs,  and  of  adjeiStive  colours  in  plain  dyeing,  was  unknown  till 
Mr.  Henry  developed  it  in  the  Memoirs  of  this  Society  f.  The  bleaching  or  whitening  of 
vegetable  fubftances  has  been  long  pra£tifed  j  but  the  knowledge  of  its  theory  could  not  be 
antecedent  to  the  xra  of  pneumatic  chemiftry.  We  might  even  at  this  moment  have  been 
unacquainted  with  the  caufe  of  the  dettruction  of  the  colouring  matter  of  vegetable  fub- 
ftances, if  the  difcovery  of  the  oxygenated  muriatic  acid,  and  its  efFedts  on  colouring 
matter,  had  not  pointed  it  out  to  us.  For  this  difcovery,  and  its  ineftimable  advantages,  the 
arts  are  indebted  to  thejuftly  celebrated  Scheele ;  and  I  am  happy  to  pay  this  tribute  to 
chemiftry  after  the  mortifying  truths  which  I  have  ftated  above. 

M.  Berthollet  loft  no  time  in  applying  the  properties  of  this  curious  and  highly  intercft- 
ing  fubftance  to  the  moft  important  practical  ufes.  His  experiments  on  bleaching  with  the 
oxygenated  muriatic  acid  proved  completely  fuccefsful,  and  he  did  not  delay  to  communi- 

*  Manchefter  Memoirs,  vol.  v.  part  i.  \  Manchefler  Memoirs,  voL  iii. 

cate 


Improved  Procefs  of  Bkacbin^-  ^  j&> 

tate  his  valuable  labours  to  the  public.     The  new  method  of  bJeaching"  was  quickly  aiid 
fciccefsfully  introduced  into  the  manufaftures  of  Mancheftcr,    Glafgovv,  Rouen,  Valen< 
ciennes,  and  Courtray ;    and  it  has  fince  been  generally  adopted  in  Great  Britain,  Ireland, 
France,  and  Germany.     The  advantages  which  refult  from  this  method,  which  accelerates 
the  procefs  of  whitening  cottons,  linens,   paper,  &c.  to  a  really  furprifing  degree  in  every 
feafon  of  the  year,  can  be  juftly  appreciated  by  commercial  people  only,  who  experience  its 
beneficial  efFefts  in  many  ways,  but  particularly  in  the  quick  circulation  of  their  capitals. 
Great  difficulties  for  a  time  impeded  its  progrefs,  arifuig  chiefly  from  prejudice  and  the 
ignorance  of  bleachers  in  chemical  prcfvifes.     Thefe  obflades  were,  however,  foon  removed 
by  Mr.  Watt  at  Glafgow,  and  by  Mr.  Henry  and  Mr.  Cooper  at   Manchefter.     Another 
difficulty  prefented  itfelf,  which  had  nearly  proved  fatal  to  the  fuccefs  of  the  operation.    This 
was  the  want  of  a  proper  apparatus,  not  for  making  the  acid  and  combining  it  with  water 
(for  this  had  been  fupplied  in  a  very  ingenious  manner  by  Mr.  "Watt  and  Mr.  Berthollet  *), 
but  for  the  purpofe  of  immerfing  and  bleaching  goods  in  the  liquor.     Tfae  volatility  of  this 
acid,  and  its  fuiFocating  vapours,  prevented  its  application  in  the  way  commonly  ufed  in  dve- 
boufcs.     Large  cifterns  were  therefore  conftrudted,  in  which  pieces  of  ituff  were  (Iratified  ; 
arid  the  liquor  being  poured  on  them,  the  cifterns  were  clofed  with  lids.     But  this  method 
was  foon  found  to  be  defeclive,  as  the  liquor  could  not  be  equally  diffafed  ;  the  pieces  were 
therefore  only  partially  bleached,  being  white  in  fome  parts  and  more  or  lefs  coloured  in 
ethers.     Various   other  contrivances  were  tried  without  fuccefs,  till  it  wjs  difcovcred  that 
an  addition  of  alkali  to  the  liquor  deprived  it  of  its  fufFocating  efFefts  without  deftroyinsi  its 
bleaching  powers.     The  procefs  began  then  to  be  carried  on  in  open  veflels,  and  has  been 
continued  in  this  manner  to  the  prefent  period.     The  bleacher  is  now  able  to  work  his 
pieces  in  the  liquor,  and  to  expofe  every  part  of  them  to  its  aftion  without  inconvenience. 
This  advantage  is  unqueftionably  great ;  but  it  is  dimihiftied  by  the  heavy  cxpence  of  the 
alkali,  which  is  entirely  loft.     It  is  moreover  to  be  feared,  that  the  alkali  which  is  added  to 
the  liquor,  though  it  does  not  deftroy  its  power  of  bleaching',  may  diminifh  it;   becaufe  a 
folution  of  the  oxygenated  muriat  of  potafh,  which  differs  from  the' alkaline  bleaching  liquor 
in  nothing  but  in  the  proportion  of  alkali,  will  not  bleach  at  all.    This  is  a  well-known  h(\ ; 
from  which  we  might  infer,  that  the  oxygenated  muriatic  acid  will  lofe  its  power  of  deftroying 
the  colouring  matter  of  vegetable  fubftances  in  proportion  as  it  becomes  neutralized  by  an 

*  M.  BerthoUet's  apparatus,  hovvKver,  is  too  complex  for  the  ufe  of  a  manufaftory  ;  Mr.  Watt's  is  better; 
but  a  range  of  four,  five  or  fix  hogftcads  or  rum  puncheons  connedteil  \\ith  one  anottier  ie  the  manner  of 
Woulfe's  diftilling  apparatus  is  preferable  to  either  of  them.  Agitators  on  M.  BerthoUet's  principle  may  be 
applied.  The  retort  or  matrafs  fliould  be  of  lead,  ftanding  in  a  water  bath  ;  its  neck  fliould  be  of  fufficient 
length  tocondenfe  the  common  muriatic  acid,  which  always  comes  over ;  and  it  fliould  form  an  inclination  to- 
wards the  body  of  the  retort,  fo  that  the  condenfed  acid  may  return  into  it.  I  beg  leave  to  ohfcrve  here,  that 
I  always  found  the  liquor  to  be  ftrongcft  when  the  diftillation  was  carried  on  very  (lowly,  I  have  alfo  found 
that  the  ftrength  of  the  liquor  'v,  much  increafed  by  diluting  the  vitriolic  acid  more  than  is  ufually  done.  The 
following  proportions  aftbrded  the  ftrongeft  liquor : 

Three  parts  manganefe. 
Eight  parts  common  fait. 
Six  parts  oil  of  vitriol. 
Twelve  parts  water. 
Th«  proportion  of  manganefe  is  fubjeft  to  variation  according  to  its  quality. 

ftlkali. 


2/0  Itnprtved  Pracefs  of  BkaeUng, 

alkali.  But  as  we  fliould  not  content  ourfelvcs  with  inferences,  however  plaufible,  when  the 
truth  maybe  eftabli  (bed  by  experiment,  and  as  I  thought  the  matter  of  fufficient  importance, 
I  made  the  following  experiments  on  the  fubje£l : 

I  beg  leave  to  premife,  that  in  all  thefe  experiments  I  made  ufe  of  one  and  the  fame  acid, 
which  was  kept  in  a  bottle  with  a  ground  glafs  ftopper,  and  fecured  from  the  inflaence  of 
light.  The  manner  in  which  I  made  the  experiments  was  fimply  this :  I  weighed  firft  of 
all  a  bottle  filKd  with  the  colouring  fubftance  which  I  meant  to  employ :  I  then  weighed  in 
a  large  and  perfectly  colourlefs  bottle  half  an  ounce  of  the  acid,  to  which  I  immediately,  but 
very  gradually,  added  of  the  colouring  fubftance  contained  in  the  former  bottle  till  the  acid 
ceafed  to  deftroy  any  more  of  its  colour.  The  bottle  with  the  colouring  fubftance  was  then 
weighed  again,  and  the  difference  between  its  prefent  and  original  weight  was  noted.  The 
fame  method  was  obferved  in  all  the  experiments. 

Experime/it  I.  To  half  an  ounce  of  oxygenated  muriatic  acid  I  added  a  folution  of  indigo 
in  acetous  acid  *,  drop  by  drop,  till  the  oxygenated  acid  ceafed  to  deftroy  any  more  colour. 
It  deftroyedthe  colour  of  160  grains  of  the  acetite  of  indigo. 

Experiment  \\.  A  repetition  of  Experiment  I.  The  colour  of  165  grains  of  acetite  of 
indicfo  was  deftroyed  in  this  experiment. 

Experiment  III.  A  repetition  of  Experiments  I  and  II.  The  colour  of  160  grains  of  the 
acetite  was  deftroyed. 

Experiment  IV.  To  half  an  ounce  of  the  oxygenated  muriatic  acid  were  added  8  drops  of 
pure  potafti  in  a  liquid  ftate.  Thiis  quantity  of  alkali  was  about  fufficient  to  deprive  the 
acid  of  its  noxious  odour.  This  mixture  deftroyed  the  colour  of  150  grains  of  the  acetite 
of  indigo. 

Experiment  Y .  A  repetition  of  Experiment  IV.  The  colour  of  145  grains  of  the  acetite 
was  deftroyed. 

Experiment  VI.  To  half  an  ounce  of  the  oxygenated  muriatic  acid,  10  drops  of  the  fame 
alkali  were  added.     It  deftroyed  the  colour  of  i   5  grains  of  the  acetite  of  indigo. 

Experiment  VII.  A  mixture  of  half  an  ounce  of  the  oxygenated  acid,  and  15  drops  of  the 
alkali,  deftroyed  the  colour  of  120  grains  of  the  acetite  ot  indigo. 

Though  I  had  taken  the  precaution  of  avoiding  the  fulphuric  acid  for  the  reafon  ftated  in 
the  foregoing  note,  I  was  not  quite  fatisfied  with  thefe  experiments,  on  account  of  errors 
which  might  have  taken  place  through  a  double  affinity.  1  therefore  made  the  following 
experiments,  in  which  I  employed  a  deco£lion  of  cochineal  in  water  inftcad  of  the  acetite  of 
indigo. 

Experiment  VIII.  To  half  an  ounce  of  the  oxygenated  muriatic  acid,  a  decoclion  of 
cochi.  eal  was  added  till  the  acid  ceafed  to  a<St  on  its  colour.  It  deftroyed  the  colour  of  390 
grains  of  the  deco<5lion. 

•  It  has  been  ufual  to  cftimate  the  ftrcngth  of  the  oxygenated  muriatic  acid  by  a  folution  of  indigo  in  ful- 
phuricacid.  This  method  was  inadmiHii  le  in  thefe  experiments  on  the  comparative  llrcngth  of  the  blcacliing 
liquor  with  and  without  alkali ;  becaule  the  fulphuric  acid  would  have  decompofed  the  muriat  of  potafh,  and 
thLreby  produced  errois.  I  therefore  adiled  to  a  folution  of  indigo  in  fulphuric  acid  after  it  had  been  diluted 
in  water,  acitite  of  lead,  till  the  fulphuric  acid  was  precipitated  with  the  lead.  The  indigo  remained  diifoived 
ja  the  acetous  acid. 

Experiment' VX., 


Imprevid  Triftfi  of  Bleaching,  t<j  | 

Eypenmetit  IX.  A  repetition  of  Experiment  VIII.  The  colour  of  385  grains  of  the  de- 
codlion  was  deftroyed  in  this  experiment, 

Experiment  X.  To  half  an  ounce  of  the  acid  fix  drops  of  the  liquid  alicali  were  added. 
This  mixture  deftroyed  the  colour  of  315  grains  of  the  deco<flion. 

Experiment  XI.  Eight  drops  of  the  alkali  were  mixed  with  half  an  ounce  of  the  acid. 
This  mixture  deftroyed  the  colour  of  305  grains  of  the  decoction. 

On  a  comparative  view  cf  the  refults  of  thefe  experiments,  it  will  appear  that  an  addition 
of  potafli  to  the  bleaching  liquor  impairs  its  ftrength  confiderably.  This  diminution  of  power 
and  the  expence  of  potafti  are  a  ferious  lofs  in  an  extenfive  manufadlure.  It  would  there- 
fore be  defirable  to  have  an  apparatus  for  the  ufe  of  the  pure  oxygenated  muriatic  acid  fimply 
dificilved  in  water,  which  is  at  once  the  cheapeft  and  beft  vehicle  for  it.  This  apparatus  muft 
be  fimple  in  its  conftruflion,  and  obtained  at  a  moderate  e.xpence ;  it  muft:  confine  the 
liquor  in  fuch  a  manner  as  to  prevent  the  efcape  of  the  oxygenated  muriatic  acid  gas,  which 
is  not  only  a  lofs  of  power,  but  alfo  an  inconvenience  to  the  workmen  and  dangerous  to  their 
health;  and  it  muft  at  the  fame  time  be  fo  contrived,  that  every  part  of  the  ftufF  which  is 
confined  in  it  fhall  certainly  and  nece/Tarily  be  expofed  to  the  aftion  of  the  liquor  in  regular 
fiicceflion.  Having  invented  an  apparatus  capable  of  fulfilling  all  thefe  conditions,  I  have 
the  pleafure  of  fubmitting  a  defcription  of  it  to  the  Society  by  means  of  the  annexed  drawing. 

Explanation   of  Plate  XI. 

Fig.  I,  is  a  fe£lion  of  the  apparatus.  It  confifts  of  an  oblong  deal  ciftern,  A  BCD, 
made  water-tight.  A  rib,  E  E,  of  afh  or  beech  wood,  is  firmly  fixed  to  the  middle  of  the 
bottom  CD,  being  mortifed  into  the  ends  of  the  ciftern.  This  rib  is  provided  with  holes 
at  F  F,  in  which  two  perpendicular  axes  are  to  turn.  The  lid,  A  B,  has  a  rim  G  G  which 
finks  and  fits  into  the  ciftern.  Two  tubes  H  H  are  fixed  in  the  lid,  their  centres  being 
perpendicular  over  the  centres  of  the  fockets  F,  F,  when  the  lid  is  upon  the  ciftern.  At  I, 
is  a  tube  by  which  the  liquor  is  introduced  into  the  apparatus.  As  it  is  neceftary  that  the 
fpace  within  the  rim  G  G  be  air-tight,  its  joints  to  the  lid  and  the  joints  of  the  tubes  muft  be 
very  clofe,  and,  if  neceflary,  fecured  with  pitch. ,  Two  perpendicular  axes,  K,  L,  made  of  afh 
or  beech  wood,  pafs  through  the  tubes  H,  H,  and  reft  in  the  fockets,  F,  F.  A  piece  of  ftrong 
canvas,  M,  is  fewed  very  tight  round  the  axis  K,  one  end  of  it  projecting  from  the  axis. 
Ihe  other  axis,  is  provided  with  a  fimiljr  piece  of  canvas.  N,  are  pieces  of  cloth  rolled  upon 
the  axis  L.  Two  plain  pulleys,  O,  O,  are  fixed  to  the  axes  in  order  to  prevent  the  cloth  fron> 
flipping  down.  The  (hafts  are  turned  by  a  moveable  handle  P.  Q,,  a  moveable  pulley, 
round  which  pafl'es  the  cord  R.  This  cord,  which  is  faftened  on  the  oppofite  fide  of  the  lid 
ffee  fig.  2)  and  paffes  over  the  fmall  pulley  S,  produces  friftion  by  means  of  the  weight  T» 
By  the  fpigot  and  fauffet  V,  the  liquor  is  let  off  when  exhaufted. 

Fig.  2.  A  plan  of  the  apparatus  with  the  lid  taken  off. 

The  Manner  of  ujing  the  Apparatus^ 
The  dimenfions  of  this  apparatus  are  calculated  for  the  purpofe  of  bleaching  twelve  or 
fifteen  pieces  of  4-  4.  calicoes,  or  any  other  fluffs  of  equal  breadth  and  fubftance.  When  the 
goods  are  ready  for  bleaching,  the  axis  L  is  placed  on  a  frame  in  a  horizontal  pofition,,  and 
one  of  the  pieces  N  being  fattened  to  the  canvas  M,  by  means  of  wooden  (kcwers  in  the  man- 
aer  reprefcnted  in  fig.  1,  it  is  rolled  upon  the  axis  by  turning  it  with  the  handle  P.    This 

6  operation 


•2*j>l,  Improved  Prc^cefi  of  Bleaching. 

operation  muft  be  performed  by  two  perlons  ;  the  one  turning  the  axis,  and  the  other 
direttin"  the  piece,  which  muft  be  rolled  on  very  tight  and  very  even.  When  the  firft 
piece  is  in  the  axis,  the  next  piece  is  faftened  to  the  end  of  it  by  fliewers,  and  wound  on 
in  the  fame  manner  <is  the  iirft.  The  fame  method  is  puifued  till  all  the  pieces  are  wound 
upon  the  axis.  The  end  of  the  laft  piece  is  then  faftened  to  the  canvas  of  the  axis  K.  Both 
axes  are  afterwards  placed  into  thcciftcrn  with  their  ends  in  the  fockets  F,  F,  and  the  ltd  is 
put  on  the  ciftern  by  palling  the  axes  through  the  tubes  H,  H.  The  handle  P  is  put  upon 
the  empty  axis,  and  the  pulley  Q^upon  the.axis  on  which  the  cloth  is  rolled  •,  and  the  cord  R 
with  the  weight  T  is  put  round  it,  and  over  the  pulley  S.  The  ufe  of  the  irittion  produced 
by  this  weight  is  to  make  the  cloth  wind  tight  upon  the  other  axis.  Bat  as  the  efFc£l  of  the 
weiiTht  will  increafe  as  one  cylinder  increafes  and  the  other  IclTens,  I  recommend  that  three 
br  four  weights  be  fufpended  on  the  cord,  which  may  be  taken  ofF  gradually  as  the  petfoa 
who  works  the  machine  may  find  it  convenient.  As  the  weights  hang  in  open  hooks  which 
are  faftened  to  the  cord,  it  will  be  little  or  no  trouble  to  put  them  on  and  to  remove  them. 

Things  being  thus  difpofed,  the  bleaching  liquor  is  to  be  transferred  from  the  vefTels  in 
which  it  has  been  prepared  into  the  apparatus,  by  a  moveable  tube  paffing  through  the  tube 
J,  and  dcfcending  to  the  bottom  of  the  ciftern.  This  tube  biing  conncfted  with  the  vefleis 
by  means  oT  leaden  or  wooden  pipes  provided  with  cocks,  hardly  any  vapours  willcfcape  in 
the  transfer.  When  the  apparatus  is  filled  up  to  the  line  a,  the  moveable  tube  is  to  be  with- 
drawn, and  the  tube  I  clofed.  As  the  liquor  rifes  above  the  edge  of  the  rim  G,  and  abovs 
the  tubes  H,H,  it  is  evident  that  no  evaporation  can  take  place  except  where  the  rim  does  not 
apply  clofely  to  the  fides  of  the  box :  which  will,  however,  form  a  very  trifling  furface  if  tht 
carpenter's  work  be  decently  done.  The  cloth  is  now  to  be  wound  from  the  axis  L  upon 
the  axis  K,  by  turning  this  ;  and  when  this  is  accomplifhcd,  the  handle  P  and  pulley  Q_are  to 
be  changed,  and  the  cloth  is  to  be  wound  back  upon  the  axis  L.  This  operation  is  of  courfe 
to  be  repeated  as  often  as  neccllary.  It  is  plain,  that  by  this  procefs  of  winding  the  cloth 
from  one  axis  upon  the  other,  every  part  of  it  is  expofed  in  the  moft  complete  manner  to  the 
a£lion  of  the  liquor  in  which  it  is  immerfed.  It  will  be  ncceflary  to  turn  at  firft  very  brifkly, 
not  only  becaufc  the  liquor  is  then  the  ftrongeft,  but  alfo,  becaufe  it  requires  a  number 
of  revolutions,  when  the  axis  is  bare,  to  move  a  certain  length  of  cloth  in  a  given  time, 
though  this  maybe  performed  by  a  fingle  revolution  when  the  axis  is  filled.  Experience 
muft  teach  how  long  the  goods  are  to  be  worked ;  nor  can  any  rule  be  given  refpetting  the 
quantity  and  ftrength  of  the  liquor  in  order  to  bleach  a  certain  number  of  pieces.  An  in- 
telligent workman  will  foon  attain  fufficient  knowledge  of  thefe  points.  It  is  hardly  neceC 
fary  to  obferve,  that  if  the  liquor  fliould  retain  any  ftrength  after  a  fet  of  pieces  are  bleached 
with  it,  it  may  again  be  employed  for  another  fet. 

With  a  few  alterations,  this  apparatus  might  be  made  applicable  to  the  bleaching  of  yarn. 
If,  for  inftance,  the  pulley  O  were  removed  from  the  end  of  the  axis  K,  and  fixed  immediately 
under  the  tube  H.;  if  it  were  perforated  in  all  directions,  and  tapes  or  firings  paffed  through 
the  holes,  fkains  of  yarn  might  be  tied  to  thefe  tapes  underneath  the  pulley,  fo  as  to  hang 
down  towards  the  bottom  of  the  box.  The  apparatus  being  afterwards  filled  with  bleaching 
■liquor,  and  the  axis  turned,  the  motion  would  caufe  every  thread  to  be  aiSled  upon  by  the 
liquor.  Several  axes  might  thus  be  turned  in  the  fame  box,  and,  being  connedled  with  each 
other  by  pulleys,  they  might  all  be  worked  by  one  perfon  at  the  fame  time ;  and  as  all  would 

turn 


BUaehh^  Pi  oeefu'^Laieral  Mot'tou  of  Fluids.  273 

turn  the  fame  way,   and  with  the  fame  /peed,  the  fkains  could  not  pofllbly  entangle  eacli 
other. 

In  order  to  (hew  the  uferjlnefs  of  this  apparatus  ftill  more  clearly,  I  requeft  the  fociety 
to  attend  to  the  following  ftatement  of  the  expencc  of  a  given  quantity  of  bleaching  liquor, 
with  and  without  alkali,  but  of  equal  ftrength. 

TVith  ktHLAhi*.  jT.  s.     d. 

8olb.  of  fait,  at  I'd.  per  lb.                     —  —                —  o  10     o 

60 lb.  of  oil  of  vitriol,  at  6'd.  per  lb.                 —  —           __  i   12     6 

30  lb.  of  manganefe             —           —             —  —               —  026 

20  lb.  of  pearl-afhes,  at  6d.  per  lb.         —         —  —           — .  o  10     o. 


■J. 

But  It  appears  by  the  foregoing  experiments,  that  the  liquor  lofes  ftrength 

by  an  addition  of  alkali.  The  value  of  this  lofs,  vi'hich  on  an  average  amounts 

to  15  per  cent,  mud  be  added  to  the  expence  —  —  —  0 


IS 


Without  Alkali. 

80  lb.  of  fait                 —                —             —  _—                _  6  10 

60  lb.  of  oil  of  vitriol         -—             —                —  —             ^^  i   12     6 

36  lb.  of  manganefe                —               —  —                  —  026 


3    3    3 
o 


£'^     5 


It  appears  from  this  calculation,  that  a  certain  quantity  of  the  liquor  for  the  ufe  of  any 
apparatus  cofts  only  2/.  5J. ;  but,  that  the  fame  quantity  of  the  alkaline  liquor  cofts 
3  /.  3  X.  3  </.  which  is  40  per  cent,  more  than  the  other.  The  aggregate  of  fo  confiderable  a 
living  muft  form  a  large  fum  in  the  extenfive  manufactures  of  this  country. 


VIII. 

Experimental  Refearches  concerning  the  Principle  of  the  lateral  Communication  of  Motion  in  Fluids 
applied  to  the  Explanation  of  various  Hydraulic  Phenomena.  By  Citizen  f.  B.  FsNTVRif 
Profejfor  of  Experimental  Philofophy  at  Modena,  Member  of  the  Italian  Society  of  the  In/iitutt 
tf  Bologna,  the  Agrarian  Society  of  Turin,  (jfc. 

(Continued  from  Page  179  of  the  prefent  Volume.) 

IPropofttion  V. 
N  an  additional  conical  tube,  the  preflure  of  the  atmofphere  increafes  the  expenditure  lit 
the  proportion  of  the  exterior  feftion  of  the  tube  to  the  fe(3ion  of  the  contrafted  vein,  what- 
ever may  be  the  pofition  of  the  tube,  provided  its  internal  figure  be  adapted  throughout  to 
the  lateral  communication  of  motion. 
We  have  feen  (Propofition  III.)  that  the  preflure  of  the  atmofphere  increafes  the  expen* 

•  I  make  no  mention  of  the  expenCe  attending  the  preparation  of  the  liquor,  it  being  the  fame  in  both 
eafet.  J 

Yofc.  IL—Sept.  1798.  Nn  diture 


274  Exptrimtnts  on  the  laitral  Cammun't cation  of  Motion  h  Fluids. 

diture  through  additional  tubes,  whatever  may  be  their  pofition.  We  fhall  in  the  next  place 
examine  the  mode  of  aftion  hy  which  the  atmofphere  produces  this  augmentation,  and  de- 
termine the  refult  from  its  caufe.  I  {hall  begin  with  the  cafe  beft  adapted  to  favour  the 
action  of  the  atmofphere,  which  is,  that  of  conical  diverging  tubes  of  a  certain  form,  which, 
we  have  not  yet  confidered. 

Let  the  extremity  AB,  fig.  lo,  Plate  VHI,  of  the  tube  ABEF  be  applied  to  an  orifice 
formed  in  a  thin  plate.  The  part  A  B  C  D  is  nearly  of  tha  figur?  of  the  contra6led  vein, 
which  form  has  been  fliewn  to  make  no  perceptible  alteration  in  the  expenditure  (Experi- 
ment IV.}  The  fluid  which  iffues  through  C  D  is  difpofed  to  continue  its  courfe  in  the 
cylindrical  form  C  D  H  G.  But  if  the  lateral  parts  of  the  diverging  conical  tube  C  E  G,, 
D  F  H,  contain  a  mafs  of  the  fluid  at  reft,  the  cylindrical  flream  C  D  H  G  will  commu- 
nicate its  motion  to  the  lateral  parts  (by  Prop.  I.)  fuccefQvely  from  part  to  part.  And  pro- 
vided the  divergence  of  the  fides  CE,  DF,  be  fuchas  is  beft  adapted  to  the  fpeedy  and  com- 
plete lateral  communication  of  motion,  all  the  fluid  contained  in  the  truncated  cone  CDEF 
vAW  at  length  acqnire  the  fame  velocity  as  that  of  the  ftream  which  continues  to  iffue 
through  C  D.  On  this  fuppofition,  while  the  fluid  ftratum  C  D  Q_R,  preferving  its  velocity 
and  thicknefs,  would  pafs  into  R  Q_TS,  a  vacuum  would  be  formed  in  the  folid  zone- 
Rm  r  S  Q_n  o  T.  Or  othervvife,  if  it  be  fuppcfed  that  the  ftratum  C  D  Q_I\i  preferving  its 
progreflive  velocity,  fliould  enlarge  in  RQ_TS,  this  cannot  happen  without  its  becoming 
thinner,  and  detaching  itfelf  from  the  ftratum  which  follows,  and  by  that  means  leaving  a 
■"  vacuum  equal  in  magnitude  to  the  zone  laft  mentioned.  A  fimilar  effeOi  would  take  place- 
through  the  whole  of  the  tube  C  E;  and  if  the  quantity  C  m  be  fuppofed  to  be  invariable, 
the  fum  of  all  thefe  void  fpaces  will  be  equal  to  the  folid  zone  VExGzYFH. 

From  this  confideration,  we  fee  that  the  lateral  communication  of  motion  caufes  the  fame 
effeiSl  in  a  conical  tube,  whether  horizontal  or  vertical,  as  gravity  produces  in  the  defcendi 
ing  tube  of  Propofition  IV.  The  atmofphere  in  this  cafe  alfo  renders  part  of  its  preffure 
adlive  on  the  refervoir,  and  at  EF.  If  the  aftion  of  the  atmofpliere  upon  the  refervoir 
increafes  the  velocity  of  the  fedion  CD,  this  velocity  will  communicate  itfelf  likewife  t^ 
the  whole  fluid  C  D  F  E,  and  the  tendency  to  a  vacuum  will  take  place  as  before  ;  but 
fmce  the  a£tion  of  the  atmofphere  is  exerted  equally  at  E  F,  it  will  take  away  at  E  F  all  the 
velocity  which  it  added  at  C  D. ;  fo  that,  being  dedufled  from  the  fame  mafs,  and  in  tbfe. 
fame  time,  at  E  F,  the  fluid  will  not  ceafe  to  be  continuous  in  the  pipe.  It  is  found  by 
computation,  that  this  will  happen  when  the  velocity  of  CD  is  increafed  in  th&  ratio  of 
C  Dmo  E  ¥\ 

By  applying  the  general  laws  of  motion  to  the  lateral  fluid  filaments  of  the  ftream  which-, 
;fl"ues  through  AB,  it  is  found  that  they  tend  to  describe  a  curve  which  commences  withia. 
the  refervoir,  for  exam.ple,  at  A,  and  continues  towards  C  S  E.  To  determine  the  nature  of 
this  curve,  it  is  requifite  taknow,  and  to  combine  together  by  calculation,  the  mutual  con- 
yergency  of  the  fluid  filaments  in  A  B,  the  law  of  the  lateral  communication  of  motibti 
between  the  filaments  themfelves  and  their  divergent  progreffion  from  C  to  £.  Thefe  cam>. 
binations  and  calculations  are  perhaps  beyond  the  utmoft  efforts  of  analyfis..  While  tUt 
tube  ABFE  poflefles  a  diflMsrent  figure  from  this  natural  curve,  the  refults  of  experiment 
will  always  differ  more  or  lefs  from  the  theory. 

JExpmmetit  XIII.  The  compound  tube  A  fi  E  jE  ©f  the  fame  fig.  io>  having  the  following 


Exper'mir.is  en  the  lateral  Cetnmt/htcathn  if  Mothn  i»  Fluids,  fjg 

dimenfions  in  lines  AB  =  EF=  i8;  AC  =  ii;  CD=:  15,5  ;  CG  =^  49  ;  and  this 
fube  being  applied  to  the  orifice  P,  fig.  i,  under  a  charge  of  32,5  inches,  the  four  cubical 
fcQt  of  water  were  emitted  in  27",^. 

We  have  feen  that,  in  the  third  experiment,  under  like  circumfl;ance«,  the  orifice  through 
a  thtn  plate  nfforded  four  cubic  feet  of  water  in  41".  The  contra£led  vein  was  0,64  of  the 
orifice.  Confequently,  by  following  the  enunciation  of  the  theorem,  the  expence  through 
the  pipe  A  B  F  ought  to  be  made  in  26'',24.  The  experiment  falls  ftiort  in  the  quantity 
l",26. 

Experiment  XIV.  Between  the  two  Conical  tubes  of  the  preceding  experiment  is'inter- 
pofed  a  cylindrical  tube  three  inches  long  and  J5,5  lines  in  diameter.  The  interpofition  of 
the  cylir.der  between  the  two  cones  was  as  in  fig.  13.  This  addition  retarded  the  expendi- 
ture i",  the  time  now  being  2ii",^. 
;  Experiment 'K'V .  The  charge  of  the  refervoir  being  conftantly  32,5  inches,  the  portion 
of  the  tube  A  B  C  D,  fig.  1 1,  had  the  fame  dimenfions  as  before  ;  the  tube  C  D  F  E  was  78 
lines  in  length,  and  its  diameter  23  lines.  To  this  horizontal  tube  I  added  three  glafs  tubes  ; 
the  firfl:  D  X  at  C  D  ;  the  fecond  N  Y  at  the  diftance  of  26  lines  from  the  firft  ;  and  the 
third  O  Z  at  26  lines  diftance  from  the  fecond.-  The. lower  extremities  of  thefe  three  tubes 
\<'ere  plunged  in  the  mercury  of  the  veffel  C^  When  the  water  was  fufFered  to  flow  through 
the  tube  AE  F  B  the  mercury  rofe  53  lines  in  the  tube  D  X ;  20,5  in  NY,  and  7  in  O  Z. 
Thefe  quantities  correfpond  with  62  inches  hoight  of  water  in  DX  ;  24  inches  in  N  Y  ; 
and  8,1  in  O  Z.     The  expenditure  of  four  cubic  feet  was  efFcded  in  25''. 

I  cut  ofFthe  portion  PN  F  E  of  the  tube,  and  the  remaining  pipe  ABN  P  emitted  the 
<^'me  quantity  in  31^'. 

In  the  truncated  conical  tube  A  C  P  B  D  N,  the  fe£l:ion  P  N  is  to  the  fe£i!on  of  the  con- 
tracted vein  (namely  0,64  of  the  fe£tion  A  B)  as  41"  to  30".  In  the  experiment  with  this 
laft  truncated  tube  the  retardation  is  confequently  no  more  than  i"lefs  than  the  theory. 

In  the  entire  tube  C  D  FE  we  have  ^  62  +  32,5  :  a/  32>S  =  W  :  24".  The  difference 
of  38  inches  elevation  of  water  in  the  two  tubes  D  X,  NY,  muft  arife  from  the  motion  of 
the -fluid  from  C  to  P  ;  it  is  i-i3th  lefs  than  by  the  theory.  The  lofs  is  fucceffively  greater 
in  the  two  portions  P  Q.,  Q_E.  The  reafon  of  this  is,  that  the  ftream  defcends  as  it  moves 
from  C  D,  fo  that  the  lateral  communication  not  being  made  uniformly  through  the  whole 
of  any  one  feclion,  the  different  parts  of  the  current  acquire  irregular  motions,  and  even 
eddies  within  the  tube;  whence  the  jet  comes  forth  by  leaps  and  irregular  fcattering.— 
Thefe  uncertain  motions  cannot  be  reduced  to  the  theory,  and  manifefl  themfelves  the  more, 
the  longer  or  the  more  diverging  the  fides  of  the  tube.  The  efFc£ts  confequently  remain  to 
be  afcertained  by  experiment. 

Experiment  XVI.  I  conftru£ted  a  tube  CD  FE  as  before,  (fig.  11)  148  lines  5ong,  and 
27  lines  in  diameter  at  E  F,  the  refl  of  the  apparatus  being  the  fame  as  in  the  foregoing 
experiment.  The  expenditure  of  four  cubical  feet  was  efFefled  in  21''';  the  inequality  and 
irregularity  of  motion  in  the  flream  were  greater  in  this  experiment  than  in  the  foregoing. 

It  was  ufelefs  to  prolong  the  tube  CD  FE  beyond  148  lines  ;  for  the  ftream  did  not  in 
that  cafe  fill  the  portion  of  tube  added  beyond  that  length,  and  the  expenditure  remained 
conftantly  at  21^'.  This  expenditure  is  jiearly  double  what  took  place  through  the  fimple 
aperture  in  a  thin  plate  ;  and  it  is  the  greateft  I  have  been  able  to  obtain  by  additional 
tubes,  the  axis  of  which  had  an  horizontal  pofition  under  a  charge  of. 32,5  inches. 

N  n  a  It 


ijS  Lateral  Motion  of  Fluids, '^Overftwing  Well. 

It  is  true,  that  by  prolonging  the  tube  C  D  FE  to  the  length  of  204  lines  Jn  the  horizon- 
tal pofition,  the  four  cubic  feet  flowed  out  in  19".     But  to  obtain  this  effe£l,  i  found  it  ne-   . 
cefTary  to  fix  a  prominence  within  the  tube  at  O,   which  forced  the  fluid  to  fly  upwards, 
and  by  that  means  to  fill  the  whole  tube. 

Experiment  XVII.  In  this  experiment  the  horizontal  tube  CD  FE,  fig.  11,  was  mora 
(Tivergent'than  in  the  foregoing  trials.  It  was  117  lines  long,  and  36  lines  in  diameter  at 
E  F.  The  reft  of  the  apparatus  was  the  fame  as  before.  The  expenditure  was  made 
in  28''i  the  ftream  did  not  fill  the  whole  fedlion  E  F.  The  refult  was  the  fame  when  fuc-^ 
cefllve  portions  of  the  pipe  were  cut  off,  until  CE  was  no  longer  than  ao  lines,  and  the 
external  diameter  18  lines.  In  this  cafe  the  ftream  filled  the  pipe,  and  lUe  expenditure  was 
alfo  made  in  28". 

When  the  length  C  E  was  20  lines,  its  external  diameter  EF  was  increafed  to  20  lines^ 
In  this  cafe  the  ftream  was  detached  from  the  fides  of  the  tube,  and  the  expence  of  four 
feet  took  place  in  42  feconds,  as  in  the  Vlth  experiment. 

»Thefe  experiments  teach  us,  that  by  varying  the  divergence  of  the  fides  of  tubes,  the 
lateral  communication  of  motion  has  a  minimum  and  a  maximum  of  efFedl.  The  minimum 
is  feen  in  the  laft  experiment.  It  appears  that  the  lateral  comriiunication  cejfes  t  >  produce- 
its  efFe£t  when  the  angle  made  by  the  fides  of  the  tube  with  each  other  exceeds  16  degrees^ 
The  Xlllth  experiment  nearly  determines  the  maximum  of  the  efFed  when  the  fame  angle 
is  about  3  degrees.     Thefe  limits  may  alfo,  perhaps,  in  a  fmall  degree   depend  upon  fomc 

fundion  of  the  velocity. 

[2"o  he  continued-} 

IX. 

yf«  jtccount  of  the  Means  employed  to  obtain  an  overf  owing  Well. 
By  Mr.  Benjamin  Vvlliamy.* 

A  E  R  M  I T  m^,  in  compliance  with  your  requefl^,  to  give  you  a  fhort  account  of  thft 
well  at  Norland-houfe,  belonging  to  Mr.  L.  Vulliamy ;  a  woric  of  great  labour  and  expence^ 
executed  entirely  under  my  diredion,  and  finiftied  in  November  1794. 

Before  I  began  the  work,  I  confidt  red  that  it  would  be  of  infinite  advantage  fliould  a  /pring 
be  found  ftrong  enough  to  rife  over  the  furface  of  the  well ;  and  though  1  thought  it  very 
improbable,  yet  I  refolved  to  take  from  the  beginning  the  fame  precautions  in  doing  the 
work  as  if  I  had  been  aflured  that  fuch  a  fpring  would  be  found.  But  although  this  very, 
laborious  undertaking  has  fucceeded  beyond  my  expedtation,  yer,  from  the  knowledge  L 
have  acquired  in  the  progrefs  cf  the  work,  I  am  of  opinion,  tliat  it  will  very  feldom  happen 
that  the  water  will  rife  fo  high  ;  nor  will  people,  I  believe,  in  general,  bs  fo  indefatigable  as. 
I'have  been  in  overcoming  the  various  difficulties  that  did  and  ever  will  occur,  in  bringing^ 
fuch  a  work  to  perfedion. 

In  beginning  to  fink  this  well,  which  has  a  diameter  of  four  feet,  the  land  fpn'ngs  were 
flopped  out  in  the  ufual  manner,  and  the  well  was  funk  and  fteined  to  the  bottom.  Whea. 
the  workmen  had  got  to  the  depth  of  236  feet,  the  water  was  judged  not  to  be  very  far  oSy, 

•  Itt  aktter  to  the  Right  Honourable  Sir  Jofeph. Banks,,  Ban.  K.  B.  P.R.  S.  Pliil.  Traaf.  1797.. 


An  artificial  overflawtitg  TFell.  5 77 

and  it  was  not  thought  fafe  to  fink  any  deeper.  A  double  thicknefs  of  fteining  was  madS 
about  fix  feet  from  the  bottom  upwards,  and  a  borer  of  5-!^  inches  diameter  was  made  ufc 
of.  A  copper  pipe  of  the  fame  diameter  with  the  borer  was  driven  down  the  bore  hole  to 
the  depth  of  24,  at  which  depth  the  borer  pierced  through  the  rock  into  the  water  ;  and  by 
the  manner  of  its  going  through  it  muft  probably  have  broken  into  a  ftratum  containing 
water  and  fand.  At  the  time  the  borer  burft  through,  the  top  of  the  copper  pipe  was  about 
three  feet  above  the  bottom  of  the  well :  a  mixture  of  fand  and  water  inftantly  rufhed  in 
through  the  aperture  of  the  pipe.  This  happened  about  two  o'clock  in  the  afternoon,  and  by 
twenty  minutes  paft  three  o'clock  the  water  of  the  well  ftood  within  17  feet  of  the  furface. 
The  water  rofe  the  firft  124  feet  in  eleven  minutes,  and  the  remaining  119  feet  in  one  hour 
and  nine  minutes.  The  next  day  fcveral  buckets  of  water  were  drawn  out,  fo  as  to  lower 
the  water  four  or  five  feet ;  and  in  a  (hort  time  the  water  again  rofe  within  1 7  feet  of  the  fur- 
face.  A  found  line  was  then  let  down  into  the  well  in  order  to  try  its  depth.  To  our 
great  furprife,  the  well  was  not  found  by  96  feet  fo  deep  as  it  had  been  meafured  before  the 
water  was  in  it ;  and  the  lead  brought  up  a  fufficient  quantity  of  fand  to  explain  the  reafon 
of  this  difference,  by  fhewing  that  the  water  had  brought  along  with  it  96  feet  of  fand  into 
the  well.  Whether  the  copper  pipe  remained  full  of  fand  or  not,  is  not  eafy  to  be  deter- 
mined ;  but  I  fhould  rather  be  inclined  to  think  it  did  not. 

After  the  well  had  continued  in  the  fame  flate  fevcral  days,  the  water  was  drawn  outfo  as 
to  lower  it  eight  or  ten  feet;  and  it' did  not  rife  a  ain  by  about  a  foot  fo  high  as  it  had  rifen 
before.  At  fome  days  interval,  water  was  again,  drawn  out,  fo  as  to  lower  the  water  as  be- 
fore J  which  at  each  time  of  drawing  rofe  lefs  and  lefs,  until  after  fome  confiderable  time  it- 
would  rife  no  more  ;  and  the  water  being  then  all  drawn  out^  the  fand  remained  perfectly 
dry  and  hard.  I  now  began  to  think  tbe  water  loft ;  and  confequendy  that  all  the  labour 
and  expence  of  finking  this  well,  which  by  this  time  were  pretty  confiderable,  had  been  in< 
vain.  There  remained  no  alternative  but  to  endeavour  to  recover  it  by  getting  out  the" 
fend,  or  all  that  had  been  done  would  be  ufelefs  ^  and  although  it  became  a  more  difficuit 
tafk  than  finking  a  new  well  might  have  been,  yet  I  determined  to  undertake  it,  becaufe  t* 
knew  another  well  might  alfo  be  liable  to  be  filled  vf\t\\  fand  in  the  fame  manner  that  this 
was.  The  operation  of  digging  was  again  neceflarily  reforted  to,  and  the  fand  was  drawn 
up  in  buckets  until  about  60  feet  of  it  were  drawn  out ;  confequently  there  remained  only 
36  feet  of  fand  in  the  well  :  that  being  too  light  to  keep  the  water  down,  in  an  inftant  it 
forced  again  into  the  well  with  the  fame  violence  it  had  done  before  j.  and  the  man  ,.ho  wa^ 
at  the  bottom  getting  out  the  fand  was  drawn  up  almoft  fufFocated,  having  been  covered  all 
over  by  a  mixture  of  fand  and  water.  In  a  fhort  time  the  water  rofe  again  within  ly  feet  of 
the  furface,  and  then  ceafed  to  rife  as  before.  When  the  water  had  ceafed  riiing  the  found- 
ing line  was  again  let  down,  and  the  well  was  found  to  contain  full  as  much  fand  as  it  did  the 
firft  time  of  the  water's  coming  into  it. 

Any  fuit'ier  attempt  towards  recovering  the  water  appeared- now  in  vain  j  and  mr.ft  peo- 
ple vv<«ild,  1  believe,  have  abandoned  the  undertaking.  I  again  coniidered,  that  tne  labour 
and  the  expence  would  be  all  loft  by  fo  doing  ;  and  I  determined  without  delay  to  tet  about 
dr.iwing  the  fand  out  through  the  water  by  means  of  an  iron  box"'  made  for  that  purpofe,> 
without  giving  it  time  to  harden  as  before.  The  labour  attending  on  this  operation  was 
¥ery  great,  as  it  was  neceflary  continually  to  draw  outthe  fand,  and  thereby  to  prevent  the' 

iand 


Vjt  Jin  artificial  cverjlevjing  Well. 

fand  From  liardening.  What  rendered  this  operation  the  more  difcouragmg  was,  that 
frequently  after  having  drawn  out  6  or  y  feet  of  fand  in  the  courfe  of  the  day,  upon  found- 
ing the  next  morning  the  fand  was  found  lowered  only  one  foot  in  the  well,  fo  that  more 
fand  miift  have  come  in  again.  This,  however,  did  not  prevent  me  from  proceeding  in  the 
fame  manner  during  feveral  days,  tho-ugh  with  little  or  no  appearance  of  any  advantage 
arifing  from  the  great  exertions  we  were  making.  After  perfevering  however  for  fome 
confiderable  time,  we  perceived  that  the  water  rofe  a  little  nearer  the  fuiface,  and  I  bo"an 
to  entertain  fome  hopes,  that  it  might  perhaps  rife  high  enough  to  come  above  the  level  of 
the  ground  ;  but  when  the  water  had  rifen  a  few  fcst  higher  in  the  well  fome  difficulties 
Occurred,  occafioned  by  accidental  circumftances,  which  very  much  delayed  the  progrefs  of 
<he  work;  and  it  remained  for  a  confiderable  time  very  uncertain  whether  the  water  would 
run  over  the  top  of  the  well  or  not, 

Thefe  difficulties  being  at  length  furmounted,  we  continued  during  feveral  days  the  pro- 
cefs  before  mentioned  of  drawing  out  the  fand  and  water  alternately  ;  and  I  had  the  fatif— 
fa£lion  of  feeing  the  water  rife  higher  and  higher,  until  at  laft  it  ran  over  the  top  of  the  well  into' 
a  temporary  channel  that  conveyed  it  into  the  road.  I  then  flattered  myfelf,  that  every 
tlifficulty  was  overcome ;  but  a  few  days  afterwards,  I  difcovered,  that  the  upper  part  of  the 
well  had  not  been  properly  conftru6ted,  and  it  became  heceflary  to  take  down  about  ten 
feet  of  brick  work.  The  water,  which  was  now  a  continued  ftream,  rendered  this  extremely 
difficult  to  execute.  I  began  by  conflruiSting  a  wooden  cylinder  12  feet  long,  which  was 
let  down  into  the  well,  and  fufpended  to  a  ftrong  wooden  ftage  above,  upon  which  I  had 
fixed  two  very  large  pumps  of  fufficient  power  to  take  oft'  all  the  water  that  the  fpring 
could  furnifh  at  1 1  feet  below  the  furface.  The  ftage  and  cylinder  were  fo  contrived  as  to 
prevent  the  pnflibility  of  any  thing  falling  into  the  well  5  and  I  contrived  a  gage  by  which 
the  men  upon  the  ftage  could  always  afcertain  to  the  greatefl  exadnefs  the  height  of  the 
water  within  the  cylinder.  This  precaution  was  efTcntially  necefl'ary,  in  order  to  keep  the 
water  a  foot  below  the  work  which  was  doing  on  the  outfide  of  the  cylinder  to  prevent  the 
new  work  from  being  wetted  too  foon.  After  every  thing  was  prepared,,  we  were  employ- 
ed eight  days  in  taking  down  10  feet  of  the  wall  of  the  well,  remedying  the  defe<^s,  and  build- 
ing it  up  again ;  during  which  time  ten  men  were  employed,  five  relieving  the  other  five, 
and  the  two  pumps  were  kept  conftantly  at  work  during  one  hundred  and  ninetj'-two  hours. 
By  the  affiftance  of  the  gage,  the  water  was  never  fufil'red  to  rife  upon  the  new  work  until 
it  was  made  fit  to  receive  it.  When  the  cylinder  was  taken  out,  the  water  again  ran  over 
into  the  temporary  channel  that  conveyed  it  into  the  road. 

The  top  of  the  well  was  afterwards  raifed  18  inches,  and  conftrufled  in  fuch  a  manner  as 
to  be  able  to  convey  the  water  five  different  ways  at  pleafure,  with  the  power  of  being  able 
to  fet  any  of  thefe  pipes  dry  at  will,  in  order  to  repair  them  whenever  occafi^r.  fliould  re- 
quire. The  water  being  now  entirely  at  command,  I  again  refolved  upon  taking  out  more 
•fand,  in  order  to  try  what  additional  quantity  of  water  could  be  obtained  thereby.  I  cannot 
exadly  afcertain  the  quantity  of  fand  taken  out,  but  the  increafe  of  water  obtained  was  very 
great;  as  inftead  of  the  well  difcharging  thirty  gallons  of  water  in  a  minute,  the  water  was 
now  increafed  to  forty-flx  gallons  in  the  fame  time. 

If  you  think.  Sir,  that  the  above  account  of  an  overflowing  well,  the  joint  producEtion  of 
nature  and  art,  is  deferving  your  attention,  1  feel  myfelf  much  gratified  in  the  pleafure  I  have 

in 


Overflowing  Well. — Sctentifle  Newt,  Vf^ 

in  giving  you  this  defcription  of  it }  and  have  the  honour  of  being  with  the  greateft  re- 
gard, &C.  &C.  B»  VULLIAMVr 

Explanation  of  Plate  XIL- 

■  Fig.  r.  ■  . 

a  Top  of  the  welJj  with  the  water  running  ove*» 
-bb  Ground  line-. 
c  Sand  lying  in  the  well. 

d  Copper  pipe.  , 

ffffff  Steining  of  the  welf. 

^1^  Double  fteining  fix  feet  from  the  bottom  upward's, 
h  Stratum  which  the  end  of  the  copper  pipe  was  driven  inta» 
Fig.  II  and  III. 
Iron  box  for  drawing  fand  out  of  the  well,  weighing  about  6olbs,  one  foot  fquare,  and 
two  feet  nine  inches  long, 
a  Handle  of  the  box. 
h  A  flip  or  door  which  opens  inwards  by  a  Joint  at  c.  There  is  another  door  like  thiy 

on  the  other  fidfi,. 
c  The  joint, 
</  1  he  centre  or  pin  of  the  joints 


SCIENTIFIC  NEWS,  AND  ACCOUNTS  OF  BOOKS^ 

AN  a  Letter  from  Sig.  Fabbroni  to  Sig.  D.  Luigl  Targioni  of  Naples,  inferted  in  the- 
85th  No.  of  the  Giornale  Letterario  di  Napoli,  I  find  an  account  of  a  very  effe£lual  com- 
pofition  for  extinguilhing  fire,  invented  by  M.  Von  Aken.     The  compofition  is, 

Burnt  alunr  .  _  _  «         _     pounds     30 

Green  vitriol  powdered'  -  -  -  40 

Cinabrefe  or  red  ochre  in  powder  -  -  -  ao 

Potters'  clay,  or  other  clay,  alfo  powdered  -  -  ,  200 

Water  -  -  -  >  _  630 

With  40  meafures  of  this  mixture  an  artificial  fire  was  extinguifhed  under  the  direcftion  of 

the  inventor  by  three  perfons,   which  would  have  required  the  labour  of  20  men  and  1500 

meafures  of  common  water.     Sig.  Fabbroni  was  commiflioned  to  examine  the  value  of  this 

invention,  and   found  in  his  comparative  trials  with  engines  of  equar  power,  worked  by 

the  fame  number  of  men,  that  the  mixture  extinguiflied  the  materials  m  cnmbuttion  in  one- 

fixth  part  lefs  time,  and  three  eighths  lefs  of  fluid  than  when  common  water  was  ufed» 

He  obferved,  as  might  indfeed  have  been  imagined  fro  n  the  nature  of  the  material,  that  the 

flame  difappeared  wherever  the  mixture  fell,  and  that  the  faline,  metallic  and  earthy  matter*: 

formed  an  impenetrable  lute  round  the  hot  combuftible  matter,  which  prevented  the  accef3> 

of  the  air,  and  confequently  the  renewal  of  the  deffruflive  procefs. 

Sig.  Fabbroni  eftimates  the  price  of  this  compofition  at  about  one  foldo  (or  halfpenny); 
per  pound,  but  remarks,  that  it  requires  fewer  hands,  and  affords  the  incalculable  advantage 
of  a  fpeedier  extinftion  of  the  fire.     Whence  he  concludes,  that  it  might  be  advifeable  toi 

keep  the  ingredients  ready  powdered  to  mix  with  water. 

.9^  Ibavr 


•28o  Mr.  Fork's  Travels  in  the  iaierior  Parts  if  Africa. 

I  have  given  this  abridged  account,  becaufc  it  Is  evident  that  fuch  inventions  are  worthy 
the  attention  of  philofophers  and  economifts,  even  though  in  the  firft  applications  they  may 
prove  Icfs  advantageous  than  their  inventors  may  be  difpofcd  to  think.  It  is  fcarcely  proba- 
ble that  this  pradice  in  the  large  way,  with  an  engine  throwing  upwards  of  200  gallons  (value 
about  3I.  los.)  each  minute,  would  be  thought  of  or  adopted,  or  that  a  fufficient  ftore  of  the 
materials  would  be  kept  in  readinefs ;  fince  at  this  rate  the  expenditure  for  an  hour  would 
demand  a  provifion  to  the  amount  of  210I.  ftcrling,  Bui  in  country  places  the  procefs,  or 
fome  variation  of  it,  might  be  applied  with  fufficient  profit  in  the  refult ;  more  efpecially  if 
it  be  confidered  that  common  fait  or  alum,  or  fuch  faline  matter  as  can  be  had  and  mixed  with 
the  water,  together  with  clay,  chalk,  or  lime,  ochreous  earth  or  common  mud,  or  eventhefo 
laft  without  any  fait,  m^y  anfwcr  the  purpofe  of  the  lute  with  more  or  lefs  efFeft;  and  ex- 
tinguiih  iin  accidentjJ  fire  with  much  greater  fpeed  and  certainty  than  clear  water  would  do. 


Mr.  Parle  has  circulated  Propofals  for  publifhing  by  Subfcription  (under  the  Patronage  of 
the  African  Affociation)  his  "Travels  in  the  interior  Parts  of  Africa,  by  Way  of  the  River 
Gambia,  performed  in  the  Years  1795,  1796,  and  1797,  by  the  Diredlion  and  at  the  Ex- 
pence  of  that  Affociation."  The  Work  will  form  One  handfome  Volume  Quarto,  and  is 
expedled  to  be  ready  for  delivery  early  in  the  enfuing  Seafon.  One  Guinea  is  to  be  paid  at 
the  time  of  fubfcribing,  which  it  is  expedcd  will  be  the  price  of  the  Book;  but  as.  the 
charges  are  not  at  prefent  afcertained,  it  is  underftood  that  a  further  payment  of  Half-a- 
Guinea  wi![  be  expefted,  provided  the  Committee  of  the  African  Affociation  fhall  certify 
th4t  fuch  demand  is  rcafonable,  Subfcripiions  are  taken  by  G.  Nicol,  Bookfeller,  Pall- 
Mali. 

Proceedings  of  the  Affociation  for  promoting  the  Difcovery  of  the  interior  Parts  of  Africa, 
containing  an  Abftraft  of  Mr.  Park's  Account  of  his  Travels  and  Difcoveries,  abridged 
from  his  own  Minutes  by  Bryan  Edwards,  Efq,  Alfo  Geographical  Illuftratioos  of  Mr. 
Park's  Journey,  and  of  North  Africa  at  large.  By  Major  Rennell.  London  :  Printed 
for  the  Affociation.  Quarto,  162  pages,  with  the  following  Maps  by  Major  Rennell. 
1,  The  Rou1:e  of  Mr.  Mungo  Park  upon  a  large  Scale.  X.  The  Lines  of  Magnetic  Variatioa 
in  the  Seas  round  Africa  ;  and  3.  A  Map  fhowing  the  Progrefs  of  Difcovery  and  Improvc- 
metit  in  the  Geography  of  North  Africa,  The  Scale  of  this  interefting  Map,  which  com- 
prehends the  whole  of  Africa,  from  the  Mediterranean  Sea  to  the  Equator,  affords  five 
Equatorial  Degrees  in  two  Inches.  The  Work  has  no  Bookfeller's  name,  and  is  not 
vendible. 

The  title-page  renders  it  needlefs  to  repeat,  that  this  book  confifts  of  two  diftindl  works< 
^f  the  latter,  whicjh  adds  no  fmall  portion  to  the  well-acquired  fame  of  its  author,  1  have  not 
yet  been  able  to  fatisfy  myfelf  that  any  abridgment  can  be  offered  to  the  Public  without 
mutilations,  which  fuch  a  fubjeft  cannot  endure.  The  reader  has  already  been  prefented 
with  the  concluding  chapter  in  cur  prefent  number.  The  whole  will  be  re-printed,  to- 
gether with  the  Maps,  in  Mr.  Park's  own  work.  Mr.  Edwards's  abftraft  of  Mr.  Park's 
Travels  contains  the  following  particulars : 

from  the  houfe  of  Dr.  Laidley  at  Pifania,  on  the  banks  of  the  river  Gambia,  but  three 

degrees 


Mr.  Sari's  Travels  in  the  interior  Parts  of  Africa,  a8t 

degrees  more  wefterly  than  the  mouth  of  that  river,  Mr.  Park  departed  to  the  eaftward  for 
the  kingdom  ofWoolii  with  two  Negro  fcrvants,  himfelf  on  horfeback  and  his  fervants  each 
on  an  afs.  He  carried  a  fmall  aflbrtment  of  bead?,  amber,  and  tobacco,  a  fewchanges  of  linen 
and  apparel,  a  pocket  fextant,  a  magnetic  compafs,  and  a  thermometer,  together  with  two 
fowling-pieces,  two  pair  ofpiftois,  and  fomc  other  fmall  articles.  At  Medina,  the  capital  of 
Woolli,  he  was  hofpitably  received,  and  proceeded  to  the  kingdom  of  Bondou,  where  the 
foveicign  compelled  him  to  furrender  his  coat,  but  neverthelefs  gave  him  five  drams  of  gold 
dull  and  plenty  of  provifions.  From  the  capital  of  Bondou  he  travelled  through  Kajaaga, 
which  is  bounded  on  the  North  by  the  Senegal  river,  where  the  French  formerly  had  a  fmall 
fa£l(Ty.  The  king  commanded  that  he  fliould  be  brought  before  him  ;  but  Mr.  Park,  who 
had  been  cautioned  to  avoid  him,  declined  the  interview,  and  efcaped  with  the  lofs  of  about 
half  his  goods  and  apparel.  Hence  he  was  conduced  to  Kaflbn,  under  the  protei^ion  of 
the  nephew  of  the  king  of  that  diftriiSl',  where  he  was  treated  wdth  great  kindnefs  and  hofpi- 
tality,  but  det.iined  fome  weeks  an  account  of  the  extreme  curiofity  of  the  natives  to  behold 
an  European.  Hence  he  proceeded  ftill  furtlier  eaftward  to  Kemmoo,  a  large  and  populous 
town,  fince  deftroyed,  but  at  that  time  the  metropolis  of  an  extenfive  kingdom  called 
Kaarta.  The  king  of  this  place,  who  received  our  traveller  with  great  kindnefs,  was  at  that 
time  at  war  with  the  neighbouring  nation  of  Bambarra,  to  the  eaftward,  through  which  the 
Joliba  or  Niger  river  flows.  Unfortunately  for  Mr.  Park,  it  was  the  opinion  of  the  fovereign 
of  Kaarta,  that  he  could  not  with  fafety  pafs  into  Bambarra  immediately  from  his  dominions  ; 
in  confequcnce  of  which  he  advifed  him  to  fliape  his  couife  to  the  northward  into  the  terri- 
tory of  the  Moors,  called  Ludamar,  on  the  border  of  the  Great  Defert ;  through  which  ter- 
ritory he  might  continue  his  route  eafterly,  and  enter  Bambarra  on  the  northern  fide.  By 
complying  with  thefe  initruiSlions,  Mr.  Park  entered  the  frontier  town  of  the  Moors,  called 
Jarra,  about  a  degree  to  the  northward  of  Kemmoo,  near  which  he  pafled  through  the 
village  of  Simbing,  whence  the  laft  difpatch  of  Major  Houghton  written  with  pencil  was 
received. 

Thus  far  our  traveller  had  continued  his  journey  to  the  eaftward  declining  to  the  north, 
tllrough  fix  degrees  of  longitude  with  about  a  degree  and  a  half  of  northing,  the  town  of 
Jarra  being  placed  in  the  map  in  about  15°  5'  north  latitude.  The  territory  through  whicli 
he  pafled  was  very  generally  clothed  with  native  woods,  and  prefented  to  the  eye  an  appear- 
ance  of  great  uniformity.  In  his  progrefs  eaftward  the  country  rofe  into  hills,  and  the  foil  be- 
came various,  but  was  every  where  fertile  in  fuch  places  as  had  been  cleared.  Bondou  in 
particular  is  aland  abounding  with  black  cattle,  fheep,  goats,  and  poultry,  with  an  excellent 
breed  of  horfes,  though  the  ufual  beaft  of  burthen  in  all  the  Negro  territories  is  the  afs. 
Animal  labour  is  no  where  applied  to  agricultural  purpofes.  The  land  is  cultivated  by  flaves, 
and  affords  plenty  of  rice  and  Indian  corn.  The  Pagans  make  an  intoxicating  liquor  from 
honey.  The  woods  furnifh  a  fmall  fpecies  of  antelope,  of  which  the  venifon  is  highly 
efteemed.  Among  wild  animals  in  thefe  countries,  the  moft  common  arc  the  hyena,  the 
panther,  and  the  elephant.  The  latter  is  often  deftroyed  for  the  fake  of  its  teeth,  but  they 
have  not  yet  tamed  it  for  the  fervicc  of  man. 

Befides  the  grains  proper  to  tropical  climates,  the  inhabitants  cultivate  in  confidcrable 

quantities,  ground  nuts,  yams,  and  pompions.     They  likewife  raife  cotton  and  indigo,  and 

Vol.  II.'-'Skpt.  1798.  Oo  have 


aSl  Mr.  Pari*s  Travels  In  the  inUrisr  Parts  of  Africa, 

'  have  fufliclent  (kill  to  convert  thefe  materials  into  tolerably  fine  cloth  of  a  rich  blue  colour^ 
and  they  make  good  foap  from  a  mixture  of  ground  nuts  and  a  ley  of  wood  alhes. 

Their  trade  with  the  Whites  is  compofed  of  flaves,  gold-duft,  ivory,  and  bees-wax.  Their 
inland  trafSc  confifts  chiefly  of  fait  procured  from  the  Moors,  and  warlike  ftores  obtained 
from  the  European  traders  on  the  Gambia  river.  Thefe  articles  are  fold  again  to  itine» 
tant  merchants  called  Slatees,  who  come  down  annually  from  diftant  countries,  fome  of 
which  are  unknown  even  by  name  to  the  natives  of  the  coaft,  with  flaves  and  a  commodity- 
called  fhea-toulou,  or  tree-butter.  This  butter,  in  Mr.  Park's  opinion,  befides  the  advan- 
tage of  its  keeping  without  fait  the  whole  year,  is  whiter,  firmer,  and  of  a  richer  flavour 
than  the  beft  butter  he  ever  taftcd  made  from  cow's  milk.  The  tree  which  affords  it  very 
much  refembles  the  American  oak  ;  and  the  nut,  from  the  kernel  of  which  the  butter  is 
prepared  by  boiling  it  in  water,  has  fomewhat  the  appearance  of  a  Spanifli  olive,  and 
is  enveloped  in  a  fweet  pulp  under  a  thin  green  rind.  The  growth  and  preparation  of 
this  commodity  are  among  the  firft  objefts  of  African  induftry  in  the  Eaftern  States,  to 
which  Mr.  Park  had  accefs.  The  natives  of  the  Gambia  countries  are  alfo  fupplicd,  ia 
confiderable  quantities,  with  fweet-fmelling  gums  and  frankincenfe  from  Bondou. 

The  government  in  all  thefe  petty  States,  though  monarchical,  is  no  where  abfolute. 
The  chiefs  form  an  ariftocracy,  which  greatly  reftrains  the  powers  of  the  Sovereign,  and 
prevent  him  from  declaring  war  or  concluding  peace  without  their  confent.  Every  confi- 
derable town  is  governed  by  a  magiftrate,  whefe  ofKce  is  hereditary,  and  who  collefls  the 
duties  and  cuftoms  from  traders,  which  are  paid  in  kind.  The  lower  orders  or  bulk  of  the 
people  are'in  a  ftate  of  flavery  or  vaflalage  to  individual  proprietors;  but  the  power  of  the 
mailer,  as  well  with  regard  to  treatment,  as  the  difpofal  of  the  flave  to  a  ftranger,  is  limited 
with  regard  to  natives.  Thefe  indulgencies  are  not  however  extended  to  captives  taken  'n\ 
war,  or  obtained  in  traffxc. 

To  return  to  Mr.  Park,  whom  we  left  at  Jarra  in  the  power  of  the  Moors,  a  fet  of  the 
worft  fanatics,  who  confider  it  as  a  meritorious  a£t  to  deftroy  a  Chriftian.  After  a  fort- 
right's  waiting,  permiiEon  arrived  from  All,  the  Moorifli  chieftain  or  king  of  the  country, 
for  him  to  proceed  in  his  journey  to  the  eaftward.  With  much  difficulty,  danger  and  infult, 
he  fucceeded  in  palling  through  a  diftridl  of  near  two  degrees  in  length,  and  was  within 
two  days  journey  of  the  frontier  town  of  Bambarra,  when  he  was  carried  back  to  the 
Moorifh  camp  by  order  of  the  chief.  On  his  arrival  he  was  thrown  into  confinement,  in 
which  he  remained  for  eight  or  ten  weeks  expofed  to  daily  infult,  robbed  of  all  his  effeiSts, 
in  danger  of  perifhing  from  the  frequent  want  of  food  and  every  other  neceflary  of  life, 
with  no  other  probable  coufequence  to  expedt  than  ultimately  to  perifh  by  the  caprice  or  fa- 
naticifm  of  the  barbarians  around  him.  Here  it  was  that  he  learned  fome  particulars  of  the 
death  of  Major  Houghton,  who  was  feduced  into  the  Defert  by  the  Moors,  robbed  of  all 
his  property,  and  died  either  for  want  of  fuftenancc,  or  by  the  violence  of  thofe  who 
refufed  to  fuppiy  that  want.  For  the  particulars  of  Mr.  Park's  adventures  we  muft  wait 
till  his  work  appears.  He  fucceeded  in  July  1796  in  efcaping  from  his  oppreflbrs.  He 
was  fortunate  enough  to  procure  his  own  horfe,  faddle  and  bridle,  a  (tvf  articles  of  his  ap- 
parel, and  his  pocket  compafs,  which  he  had  concealed  in  the  fand.  The  joy  he  experienced 
at  his  efcape  foon  fubfiJed  into  more  anxious  emotions.  Alone  in  the  woods  of  Africa,  ex- 
pofed to  the  ferocity  of  wild  beafts,  and  the  dread  of  meeting  again  with  men  more  fero- 
cious 


Mr.  Park's  Travels  tn  the  htmor  Paris  of  jf/rlcg.  283 

cious  than  thofe  animals  }  finking  under  the  rage  of  hunger,  and  the  ftill  more  Intolerable 
torture  of  thirft,  it  was  in  vain  that  he  chewed  the  bitter  leaves  of  the  trees,  ortlimbcd 
to  look  around  him  for  a  watering-place.  A  feafonable  fhower  however  favcd  him  from 
perifhing  during  the  firft  night ;  and  after  a  weary  courfe  without  food  or  water  for  the 
grcatcft  part  of  the  day  follov.'ing,  he  had  the  good  fortune  to  meet  with  relief  among  a  few 
huts  of  Negro  {hepherds.  In  this  manner,  and  with  no  better  dependance  forfupport  than 
the  kindnefs  of  the  moil  wretched  of  human  beings,  he  proceeded  on  the  objedt  of  his 
miflion  for  fifteen  days ;  when,  on  the  morning  of  the  i6th,  having  been  joined  by  fome 
Negroes  who  were  travelling  to  the  town  of  Sego,  he  had  the  inexpreffible  fatisfaiSlion  of 
beholding  the  obje£l  of  his  wifhes,  the  long  fought  Niger  glittering  to  the  morning  fun  as 
broad  as  the  Thames  at  Weftminfter,  and  flowing  flowly  from  weft  to  eaft  through  the 
middle  of  a  very  extenfive  town,  which  his  fellow  travellers  told  him  was  Sego,  the  ca- 
pital ©f  the  great  kingdom  of  Bambarra,  which  Major  Rennell  places  in  14°  10'  Northt 
latitude,  and  z"  16'  Weft  longitude  from  Greenwich. 


\_ne  remainder  of  this  AbJraSl  in  our  next\ 


C    a84    ] 


A  TABLE  for  rcdncing  the  Ufiitics  of  the.Englifh  Inch,   Gallon,  and  Grain  Into 

Metres,  Litres,  and  Grammes. 


■-  '''  ■ 

Cubic      ~ 

Ale  GaN 

VVineGal- 

a 

Cubic 

Ale    Gal- 

WintGal- 

fnches    in 

Ions  of  282 

lonsof  13  1 

Grains    ir 

w 

[iiches    in 

lonsof  282 

!onsof  2ji 

Grains    in 

^ 

Metres. ' 

Litre?.  -  ■ 

Jnclies    in 

Inches    in 

Grammes. 

'd 

Metres. 

Litres. 

Inches    in 

Inches    in 

Grammes. 

bl. 

e: 
Ci 

Litres.-  - 

Litres. 

, 

to 

c 
U3 

Litres. 

Litres. 

1 

0.0254 

~0'.OI6T 

4.6168 

^.7-821 

0.0435 

5i 

1 .2950 

0.8349 

235.46 

192.89 

2.i!207 

9. 

0.0508 

0.0327 

9.2336 

7.5643 

0.0871 

52 

1.3204 

0.8513 

240.07 

196.67 

2.2642 

8 

0.0762 

0.0191 

13-850 

11.346. 

0.1306 

53 

1.3458 

0.8677 

244.69 

200.45 

2.3078 

4 

0.1016 

0.0655 

18.467 

15.128 

0.1742 

54 

1.3711 

0.8810 

249.31 

204.24 

2.3513 

5 

0-1270 
0.1523 

0  0819 

23.084 
27-701 

18.911 

0.2177 

55 

56 

1.3965 

0.9004 

253.92 

208.02 

2.3948 

fi 

0.0982 

22.693 

0.2613 

1.4219 

0.9168 

258.54 

211.80 

2.4384 

7 

0.1777 

0.1146 

32.318 

26.475 

0.3018 

57 

1 .4473 

0.9332 

263.16 

215.58 

2.4819 

R 

0.2031 

0.1310 

36.934 

30.257 

0.3483 

58 

1 .4727 

0.9495 

267.77 

219.36 

2.5255 

0 

0.2285 

0.1473 

41.551 

34.039 

0.3919 

59 

1.4981 

0.9659 

272.39 

223.15 

2.5690 

10 

0.2539 

0.2793 

0.1637- 

46.168 

37.821 

0.43  5  i 

60 
61 

1.5235 

0.9823 

277.01 

226.93 

2.6126 

11 

0.1801 

50.785 

41.601 

0.4790 

1.5489 

0.9986 

281.63 

230.71 

2.6561 

ly 

0.30^7 

0.1965 

55.402 

45.386 

0.5225 

62 

1.5743 

1.0150 

286.21 

234.49 

2.6996 

13 

0.3301- 

0.2128 

60.018 

49.168 

0.5661  - 

63 

1.5997 

1.0314 

290.85 

238.28 

2.7432 

14 

0.3555 

0.2292 

6  1.635 

52.950 

0-6096 

64 

1.6251 

1.0478 

■295.48 

242.06 

2.7867 

15 

0.3809 

0.2156 

69.252 

56-732 

0.653 1 
0.6967 

65 

1.6505 

1.0641 

300.09 

245.84 

2.8303 

16 

0.4063 

0.2619 

73.869 

60.514 

66 

1.6758 

1 .0805 

304.71" 

249.62 

2.8738 

17 

0.4317 

0.2783 

78.486 

64.297 

0.7402 

67 

1.7012 

1.0969 

309.33 

253.40 

2.9174 

18 

0.4570 

0.2947 

83.102 

68.079 

0.7838 

68 

1.7266 

1.1132 

313.94 

357.19 

2.9609 

m 

0.4824 

0.3111 

87.719 

71.861 

0.8273 

69 

1.7520 

1.1296 

318.56 

260.97 

3.0044 

20 

0.5078 

0.3274 

92.336 

75.643 

0.8709 

70 

71 

1.7774 

1.1460 

323.18 

264.75 

3.0480 

••^1 

0.5332 

0.3438 

96.953 

79.425 

0-9144 

1.8028 

1.1623 

327.79 

268.53 

3.0915 

m 

0.5586 

0.3602 

101.57 

83.207 

0.9579 

72 

1.8282 

1.1787 

332.41 

272.31 

3.1351 

V3 

0.5840 

0.3765 

106.19 

86.989 

1.0015 

73 

1.8536 

1.1951 

337.03 

276.10 

3.1786 

9  + 

0.6094 

0.3929 

110.80 

90.772 

1.0150 

74 

1.8790 

1.2115 

341.64 

279.88 

3.2222 

25 

0.6348 

0.4093 

115.42 

94.554 

1.0886 

75 
76 

1.9044 

1 .2278 

346.26 

283.66 
287.44 

3.2657 

9fi 

0.6602 

0.4256 

120.04 

98.336 

1.1321 

1.9298 

1.2442 

350.88 

3.3092 

97 

0.6856 

-0.4420 

124.65 

102.12 

1.1757 

77 

1.9552 

1.2606 

355.49 

291.23 

3.3528 

^8 

0.7110 

0.4584 

129.27 

105.90 

1.2192 

78 

1.9805 

1.2769 

360.11 

295.01 

3.3963 

•;q 

0.7364 

9.4748 

133.89 

109.68 

1.2627 

79 

2.0059 

1.2933 

364.73 

298.79 

3.4399 

30 

0.7617 

0.4911 

138.50 

113.46 

1.3063 

80 
81 

2.0313 

1.3097 

369.34 

302.57 

3.4834 

;-ii 

0.7871 

0.5075 

143.12 

117.25 

1.3498 

2.0567 

1.3261 

273.96 

306.35 

3.5270 

m 

0.8125 

0.5239 

147.74 

121.03 

1.3934 

82 

2.0821 

1.3424 

378.58 

310.14 

3.5705 

33 

0.8379 

0.5402 

152  35 

124.81 

1.4369 

83 

2.1075 

1,3588 

383.19 

313.92 

3.6140 

34 

0.8633 

0.5566 

156.97 

128.59 

1.4804 

84 

2.1329 

1.3752 

387.81 

317.70 

3.6576 

35 

0.8887 

0-5730 

161.59 

132.38 

1.5240 

85 
86 

2.1583 

1.3915 

392.43 

321.48 
325.26 

3.7011 

3b 

0.9141 

0.5894 

166.20 

136.16 

1.5675 

2.1837 

1.4079 

397.05 

3.7447 

37 

0.9395 

0.6057 

170.82 

139.94 

1.6111 

87 

2.2091 

1.4243 

401.66 

329.05 

3.7882 

33 

0.9649 

0.6221 

175.44 

143.72 

1.6546 

88 

2.2345 

1.4407 

406.28 

332.83 

3.8317 

S^l 

0.9903 

0.6385 

180.06 

147.50 

1.6982 

89 

2.2599 

1.4570 

410.90 

336.61 

3.8753 

40 

1.0157 

0.6518 

181.67 

151.28 

1.7417 

90 
91 

2.2852 

1.4734 

415.51 

340.39 

3-9188 

41 

1.0411 

0.6712 

189.29 

155.07 

1.7852 

2.3106 

1.1898 

420.13 

344.18 

3.9624 

49 

1.0664- 

0.6876 

193.91 

158.85 

1.8288 

92 

2.3360 

1.5061 

424.75 

347.96 

4.0059 

43 

1.0918 

0.7040 

198.52 

162-63 

1.8723 

93 

2.3614 

1.5225 

429.36 

351.74 

4.0495 

44 

1.1172 

0.7203 

203.14 

166.41 

1.9159 

94 

2.3868 

1.5389 

433.98 

355.52 

4.0930 

45 

1.1426 

0.7367 

207.76 

170.20 

1.9594 

95 
96 

2.4122 

1.5553 

438.60 

359.30 

4.1365 

46 

1.1680 

0.753  K 

212.37 

173.98 

2.0030 

2.4376 

1.5716 

443.21 

363.09 

4.1801 

47 

1.1934 

0.7694 

216.99 

177.76 

2.0465 

97 

2.4630 

1.5880 

447.83 

366.87 

4.2236 

48 

1.2188 

0.7858 

221.61 

181.54 

2.0900 

98 

2.4884 

1.6044 

452.45 

370.65 

4.2672 

4') 

1.2442 

0.8022 

226.22 

185.33 

2.1336 

99 

2.5138 

1.6207 

457.06 

374.43 

4.3107 

»0 

1.2696 

0.8186 

230.84 

189.11 

2.1771 

100 

2.5392 

1.6371 

461.68 

378.21 

4.3543 

[Phiios.  Journal.    To  face  page  284,  Vol.  II, 

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Sfif 


JOURNAL 

OB"  . 

NATURAL   PHILOSOPHY,  CHEMISTRY^ 

THE    ARTS. 


OCTOBER     1798. 


ARTICLE    I. 

Curious  Ctrcumjfauces  upon  ivh'tch  the  Vitreous  or  the  Stony  CharaEfer  of  Whinjlone  ancl Lavx 
refpeElively  depend ;  with  other  FaHs.  In  an  Account  of  Experiments  made  by  Sir  J  AMES 
Hall,  Bart.  F.R.  and  A.S.S.  Edin* 


G, 


'N  the  5th  March,  and  i8th  of  June,  Sir  James  Hall  read  to  the  Royal  Society  of 
Edinburgh  an  account  of  a  feries  of  experiments  on  whinftone  and  lava.  Thefe  experi- 
ments, which  relate  to  the  theory  of  the  earth  publiflied  by  the  late  Dr.  Hutton,  had  bcea 
projefted  by  Sir  James  Hall  in  1 790  ;  at  which  time  he  read  a  paper  to  the  fociety  on  the 
formation  cf  granite  and  other  unftratified-fubftances.  He  had  then  begun  a  few  experi- 
ments, but  ha.l  been  obliged  by  fome  circumftances  to  difcontinue  them.  Having  obtained^ 
however,  very  promifing  appearances  of  fuccefs,  they  were  again  refumed,  and  carried  into- 
elFedt  in  the  courfe  of  laft  winter  \,  In  the  execution  of  the  experimental  part,  Sir  James 
Hall  acknowledges  himfelf  greatly  indebted  to  the  affiflance  of  Dr.  Kennedy. 

The  fubjeiSl  of  the  communication  was  fuggefted  by  fome  obvious  and  plaufible  objec- 
tions which  have  lately  been  urged  againft  Dr.  Hutton's  fyftem.  Whinftone  or  bafaltes 
being  confidered  in  that  fyftem  as  having  attained  its  prcfent  pofition  in  a  ftate  of  igneous 
fufion,  it  has  been  alledged,  as  a  fufhcient  refutation  of  this  hypothefis,  that  whinftone, 
when  made  to  undergo  fufion  in  one  of  our  furnaces,  yields  glafs,  a  fubftance  very  different 
from  the  original  ftone }  the  formation  of  which  cannot  therefore  be  afcribed  to  the  a£lioa 
of  fire. 

*  Abftraft,  by  favour  of  the  Author,  from  his  Paper  which  will  appear  in  the  Edin.  Tranf.  vol.  v. 
+  Sir  James  Hall  fiiowed  the  refult  of  his  firft  fuccefsful  experiment  at  a  meeting  of  the  Society  on  the  5th: 
•f  February,  179?. 

Vol.  IL— Oct.  1798^.  Eg  .  This 


•286  Experimental  Inve/ligat'ioti  of  the  Caufes  of 

This  difficulty  had  formerly  occurred  to  Sir  James  Hall;  who  had  endeavoured  to  obviat*' 
It  by  ftating,  that  the  mafs  during  flow  refrigeration  in  the  bowels  of  the  earth  had  under- 
gone a  change  Cmilar  to  that  of  glafs  into  Reaumur's  porcelain  ;  and  that  by  cryftallization 
it  had  loft  the  vitreous,  and  aflumed  the  ftony  charafter.  The  truth  of  this  explanation 
has  now  been  amply  confirmed  by  thefe  experiments,  which  comprehend  feven  different 
fpccies  of  whinflone.  Each  of  the  original  fubltances  was  reduced,  by  fufion  and  fubfe- 
quent  rapid  cooling,  to  a  ftate  of  perfeft  glafs.  This  glafs,  being  again  placed  in  the 
furnace,  was  fubjefted  to  a  fecond  fufion.  The  heat,  being  then  reduced  to  a  temperature 
^encirally  about  28°  of  Wedgwood,  was  maintained  itationary  for  fome  hours  ;  when  the 
crucible  was  either  immediately  removed,  or  allowed  to  cool  with  the  furnace.  The  con- 
fequence  was,  that  in  every  cafe  the  fubftancc  had  loft  the  charadler  of  glafs,  and  by 
cryftallization  had  aflumed  in  all  refpeds  that  of  an  original  whinftone. 

It  muft  be  owned,  that  in  moft  cafes  the  new  produdtion  did  not  exaclly  refemble  the 
particular  original  from  which  it  was  formed,  but  fome  other  original  of  the  fame  clafs  j 
owing  to  accidental  varieties  in  the  mode  of  refrigeration,  and  to  chemical  changes  which 
unavoidably  took  place  during  the  procefs.  In  the  cafe,  however,  of  the  rock  of  Edin- 
burgh Caftle,  and  of  that  of  the  bafaltic  columns  of  Staffa,  the  artificial  fubftances  bear  a 
complete  refemblance  to  their  originals,  both  in  colour  and  texture. 

Sir  James  Hall  conceives,  that  the  objcftion  to  Dr.  Button's  fyftem,  mentioned  above, 
is  thus  completely  obviated ;  fince  the  ftony  character  of  whinftone  is  ftiown  to  be  the 
natural  confequence  of  the  flow  refrigeration,  which,  according  to  that  fyftem,  muft  have 
taken  place  in  the  bowels  of  the  earth,  as  the  fubftancc  of  whinftone  pafled  from  a  liquid  to 
a  folid  ftate. 

Experiments  were  made  with  equal  fuccefs  on  lava.  This  clafs  of  bodies  is  known  to 
pofl'efs  the  cryftalline  and  ftony  chara£ler,  in  common  with  whinftone,  and  to  refemble  it 
fo  much,  that  in  many  cafes  the  two  fubftances  cannot  be  diftinguiflied  by  their  external 
appearance  *.  In  others,  however,  certain  circumftances  occur  by  which  they  are  charac- 
terized. But  in  confequence  of  fufion  thefe  diftinguilliing  marks  dlfappear ;  and  the  glafs 
of  a  lava  feems  in  no  refpedt  to  differ  from  that  of  a  whin.  Sir  James  Hall  therefore  infers 
that  the  two  fubftances  are  intrinfically  the  fame,  and  afcribes  their  differences  to  the  cir- 
cumftances under  which  each  clafs  paffed  from  a  liquid  to  a  folid  ftate  ;  the  lavas  having 
cooled  in  the  open  air,  and  the  whins,  according  to  Dr.  Hutton,  in  the  bowels  of  the  earth. 
Six  lavas,  four  of  which  f  made  part  of  undoubted  currents  of  ^tna  and  Vefuvius,  and 
broken  from  thofe  currents  by  Sir  James  himfelf,  were  fubmitted  to  experiment.  The 
glafs  produced  by  fufion  and  rapid  cooling,  yielded,  when  treated  like  the  glafs  of  whin,  the 
fame  kind  of  cryftallized,  ftony,  or  earthy  maffes,  completely  refembling  an  original  whin  or 
lava. 

In  the  courfe  of  thefe  experiments,  the  fufibilities  of  the  various  original  fubftances,  and 
of  thofe  artificially  produced,  were  afcertained  with  much  care  by  Wedgwood's  pyrometer, 

•  Thefe  obfervations  are  applicable  to  lavas  in  general,  comprehending  all  thofe  of  iEtna  and  Vefuvius ;  but 
do  not  ftriftly  apply  to  fome  of  the  lavas  of  the  Lipari  Ifles,  and  of  Ifchla,  which  poflcfs  fome  curious  and  in- 
terefting  properties  to  be  mentioned  in  a  future  communication,    H. 

i  Ko.  S)  9)  II  anil  '^  0^  fhc  tabic. 

an(i 


the  Stony  and  the  Fitrecus  Char  alters  in  Lavas.  all 

and  are  dated  In  the  annexed  table,  which  may  be  depended  upon,  in  every  example,  to 
Mpithin  two,  or  at  mod  three  degrees.  The  artificially  cryllallized  fubftances  have  been 
denoted,  at  Dr.  Hope's  fuggeftion,  by  the  name  of  cryjiallite. 

The  various  fufibilities  ftated  in  the  table  afford  fome  conclufions  of  confequence.  The 
whins  fiibmitted  to  trial  are  more  refracSlory  than  the  lavas  j  though  their  excefs  in  this  re- 
fpc£l  is  not  great,  fince  the  mofl:  fuftble  of  the  former  clafs  equal  the  moft  refradory  of 
the  latter.  The  glafles  are  all  incomparably  more  fufible  than  the  original  ftones.  This 
laft  circumllance  has  long  been  known  as  a  fail  •,  but  Sir  James  propofes  to  fugged  the 
theory  of  it,  and  of  all  the  peculiarities  which  occurred  in  thofe  experinieots,  in  a  fecond 
communication  which  he  means  foon  to  lay  before  the  Society. 

It  is  obfervable,  that  the  lava  No.  12  is  fufible  at  i8  ;  that  is,  it  refembles  in  this  pro- 
perty the  moft  fufible  glafles.      And  it  is  in  fadt  a  glafs  ;  for,  being  lifted  in  a  foft  date  from 
n  flowing  lava  of  Vefuvius  by  Sir  James  Hall,  it  quickly  cooled,  and  has  of  confequence 
affumcd  the  vitreous  charafter  in  every  refpedl :  for,   befides  ks  eafy  fufibility,  it  pofleflbii 
the  fliining  furface  and  fradlure  of  glafs.     This  fubftance,  being  treated  like  the  artificial 
glafles  of  whin  and  lava,  crydallized  like  thefc,  and  aflumed  the  chara6ter  of  a  dony  laVa, 
both  in  texture   and  in  difficult  fufibility,  fince  it  foftencd  only  at  35°.     Here  then  is  a 
proof  beyond  difpute,  that  the  dony  chara£ter  of  a  lava  isoccafioned  folely  by  flow  cooling. 
Although  the  internal  drudure  of  lava  was  thus  accounted  fo_r,  yet  Sir  James  was  em- 
barrafled  with  the  date  of  its  external  furface ;  which,   though  cooled  in  conta6l  with  the 
open  air,  is  feldom  or   ever  vitreous,  holding  an  intermediate  dation  between  glafs  and 
done  ; — bqt  thi?  difficulty  was  removed  by  a  circumdance  which  took  place  in  the  courfe  of 
thefe  experiments.     It  was  found  that  a  fniall  piece  of  glafs  of  any  of  the  lavas,  or  of  feveral 
of  the  whins,  being  introduced  into  a  muffle,  the  temperature  of  which  was  at  any  point 
between  the  20th  and  the  22d  degree  of  Wedgwood's  fcale,  the  glafs  became  quite  loft  ia- 
the  fpace  of  one  minute ;  but,  being  allowed  to  remain  till  the  end  of  a  fecond  minute,  it  was 
found  to  have  become  hard  throughout  in  confequence  of  a  rapid  crydallization,  to  have 
lodits  character  of  glafs,  and  to  have  become  by  12  or  14  degrees  more  infufible,  being. 
iraafFefled  by  any  heat  under  30,  though  the  glafs  had  been  fufible  at  18°  or  at  16.     This, 
accounted  for  the  fcoria  on  the  furface  of  lavas  ;  for  the  fubdance  even  at  the  furface,  being 
in  contact  with  the  flowing  dream  and  furrounded  with  heated  air,  could  not  cool  with 
exceffive  rapidity;  and  the  experiment  fliows,  that  diould  any  part  of  the  mafs,  in  defcend- 
ing  heat,  employ  more  than  one  or  two  minutes  in  cooling  from  22  to  20,  it  would itii 
fallibly  lofe  its  vitreous  chara£ler.  ,       .! 

The  internal  phaenomena  of  volcanos  being  thus  explained  by  the  properties  of  commoa 
fire,  and  the  refemblancc,  or:identity,  of  many  lavas  and  of  whindone  being  thus  edablifh- 
ed.  Sir  James  Hall  conceives,  that  the  powerful  arguments  advanced  by  Dr.  Hutton  to 
prove  the  igneous  origin  of  whindone  and  other  mineral  bodies,  are  very  drongly  corrobo- 
rated ;  fince  thefe  experiments  fhow  that  thefe  fubdances  may  have  been  formed  by  a  fimple 
extenfion  of  the  fame  caufes  which  continue  at  this  day  to  agitate  various  parts  of  our 
globe. 

Independently  however  of  any  allufion  to  fyftem  or  to  general  theory,  Sir  James  Hall 
flatlets  himfelf  that  thefe  experiments  may  be  of  fome  importance  by  fimplifying  the  hiftory 
^f  volcanos }  and  above  all  by  fujcrfeding  fome  very  extraordinary,  and-,  he  conceives,, 

P  P  ?  Mnphilofophical 


'»S8  Reinaridhle  H-jhUmhs  af  Folcuntc  PraJuSIs, 

tiiiphllofoplilcal  opinions  advanced  with  regard  to  volcanic  heat,  which  has  been  dated  as 
po{refling  very  little  intenfity,  and  as  ailing  by  fome  occult  and  inconceivable  influence,  or 
with  the  help  of  fome  invifiblc  agent,  fo  as  to  produce  liquidity  v/ithout  fufion,  Thefe 
fuppofitions,  which  have  been  maintained  ferioufly  by  fome  of  the  moll  celebrated  na- 
turaliRs  in  Europe,  have  originated  from  the  difFicuky  of  accounting  for  the  ftony  charadler 
of  lavas,  when  compared  with  that  of  glafs,  which  they  aflume  in  confequence  of  fufion  in 
our  furnaces.  But  now  he  hopes  we  may  be  relieved  from  the  necefiity  of  fuch  violent 
efforts  of  imagination,  fince  the  pha^noniena  have  been  fully  accounted  for  by  the  fimple 
though  unnoticed  principle  of  refrigeration,  and  have  been  repeated  again  and  again  with 
enfe  and  certainty  in  a  fmall  chamber  furnace. 

T  ABLE. 
The  fufibilities,  according  to  Wedgwood's  pyrometer,  dated  in  the  following  table,  were 
afcertained  by  heating  the  fubffances  in  a  muffle,  in  which  they  could  be  dillindlly  ob- 
ferved,  while  expofed  to  the  a£lion  of  the  heat.  A  fmall  piece  of  the  fubftance  to  be 
examined  being  put  into  the  muffle,  a  pyrometer-piece  was  placed  clofe  befide  it,  and  the 
heat  raifed  gradually.  The  fubifance  was  touched  at  intervals  with  a  {lender  iron  rod  ; 
and  when  found  fo  foft  as  to  yield  eafily  to  flight  preffurc,  the  pyrometer  was  withdrawn, 
and  meafured. 
[  All  the  whins  except  No.  -were  taken  from  their  oriijinal  rocks  in  the  neighbourhood  of  Edinl  urgh.  ] 


Original 
fubftc-iiices  . 
foftened. 

Glafs 
foftened. 

Ciyftallite 
foftened. 

No.  I. 

Whin  from  a  quarry  on  the  Water  of  Leith, 

4^545 

'7515 

33 

No.  2. 

Whin  of  the  rock  of  Edinburgh  Caftle, 

45 

24;23 

35 

No.  3. 

Whin  of  bafaltic  columns — Hill  of  Arthur's  Seat, 

•  55 

18 

35 

No.  4. 

Wliin  from  the  fouth  fide  of  Arthur's  Scat,  near 
Duddyttone, 

43 

24 

38 

No.  5. 

Stone  of  the  nature  of  whin,  found  in  large  blocks 
in  the  bed  of  Water  of  Leith, 

55 

16 

37 

No.  6. 

,   Whin  of  Salllbury  Rock, 

55 

24 

38540 

No.  7. 

Whin  of  bafaltic  CiJumns,  StafFa, 

38 

— 

— 

No.  8. 

Lava  of  JEtaa,  T?hich  deftroyed.part  of  Catania  in 
1669, 

34 

20 

38 

No.  9. 

Lava  near  Pledmonte — iEtna, 

32 

18 

36 

No.  10. 

Lava  of  La  Motta  di  Catania — .5itna, 

38542 

i3 

36 

No.  1 1 . 

Lava  of  Torre  del  Greco — Vefuvius, 

40 

18 

27528 

No.  18. 

Lava  lifted  red  hot  from  a  flowing  ftream  on  Vefu- 
vius, by  Sir  James  Hall, 

18 

18 

35 

No.  13. 

Lava  from  Iceland, 

35 

'5 

43 

1 

Totaps  afd  Sfda /otiftJ  hi  Volcanic  Produflu  xif 


II. 

On  ihe  Anatyfn  of  Pumic(f  •which  is  found  to  contain  PotnJJj;  and  of  Bafaltes  and  Lava  containing 

Soda.      Bv  Dr.  KENNEDY' '*. 


o. 


'N  the  jth  of  February  1798,  an  analyfis  of  pumice  was  communicated  to  the  Royal  So- 
ciety of  Edinburgh  by  Dr.  Kennedy.  By  this  analyfis  he  (hewed  that  the  pumice  contained 
potafli  as  one  of  its  component  parts.  The  fpecimen  analyfed  was  of  the  common  kind, 
having  a  fibrous  texture  and  a  fiiky  luilre.  By  a  heat  of  60'  of  Wedgwood,  it  was  convert- 
ed into  a  kind  of  glafly  enamel ;  and  in  a  muffle,  even  at  a  heat  of  35  or  40,  was  fo  far 
altered,  that  its  fibrous  texture  could  no  longer  be  diftinguifhed.  Befides  potafli,  it  contain- 
ed files,  argill,  and  a  fmall  quantity  of  iron  ;  but  no  lime  or  magneCa. 

Several  other  varieties  of  the  common  kinds  of  pumice  ufed  in  the  arts,  were  found  at 
fufible  as  the  fpecimen  above  mentioned,  and  gave  the  fame  kind  of  glafly  enamel. 

The  refult  of  the  analyfis,  with  refpe£l  to  the  earths  and  iron,  correfponds  very  nearly 
ilvith  the  refult  of  Mr.  Klaproth's,  publiflied  in  the  2d  vol.  of  his  Beitrage ;  only  he  did  not 
find  potafli  in  the  fpecimen  he  analyfed  j  in  which,  however,  there  was  probably  fome  faline 
fubftance  ;  for  the  fame  kind  of  pumice  melted  in  the  porcelain  furnace  of  Berlin ;  in  which 
a  compound  confifting  only  of  files,  argill,  and  a  minute  portion  of  iron,  would  certainly 
not  have  melted.  The  heat  of  this  furnace  was  1 36  of  Wedgwood. — See  Klap.  Beytr,  vol.  2d, 
p.  88. 

On  the  6th  of  Auguft  Dr.  Kennedy  announced  to  the  Society,  that  he  had  difcovered 
mineral  alkali  in  feveral  varietiesof  bafaltes  or  whinftone.  He  found  by  chemical  analyfis, 
that  the  alkali  exifl;ed  in  thefe  fubftances  in  a  ftate  of  very  intimate  combination  withthck 
earthy  bafes ;  and  that  it  was  with  difiiculty  feparated,  even  by  the  ftrongefl:  acids. 

Dr.  Kennedy  alfo  analyfed  a  fpecimen  of  lava  from  iEtna,  at  the  requeft  of  Sir  James 
Hall,  who  thought  it  extremely  probable  that  alkali  would  be  found  in  lava,  as  well  as  ia 
bafaltes,  on  account  of  the  great  refemblance  which  thefe  two  fubftances  have  to  each  other, 
both  in  external  appearance  and  in  many  chemical  properties.  The  fpecimen  was  broken, 
by  Sir  James  Hall  and  Dr.  Hume,  from  the  celebrated  current  of  lava  which  in  1669  de- 
ftroyed  part  of  the  town  of  Catania.     It  was  found,  like  the  bafaltes,  to  contain  foda. 

One  of  the  fixed  alkalis,  potafh,  has  already  been  difcovered  in  fl;ony  fubftances  by  the 
celebrated  Mr.  Klaproth,  to  whom  the  world  is  indebted  for  fo  many  analyfes  performed 
with  the  greateft  flcill.  The  experiments  above-mentioned  fhow,  that  the  other  fixed 
alkali,  foda,  likewife  exifts  in  ftony  fubftances. 

*  Abflxail,  by  favour  of  the  Author.    This  paper  will  appear  in  the  5th  vol.  of  the  Edhiburgh  Tranfafttous, 


III,  Sfc^fnmenii 


j^bc  Preparation  of  the  Oxygenated  Muriat  ef  Pot^r^ 

III. 

Experiments  and  Ohfervations  on  the  Preparation,  and  feme  remarkable  Properties  (f  the  Oxygsnateif 
Muriatr  ef  Pct-ajh.     By  Mr.  ThoM-AS  HorZE,jiin.  * 


H. 


.AVING  an  opportunity  in  preparing  the  oxygenated  muriatic  acid  for  the  purpofe 
oi  bleaching,  by  a  fmall  extenfion  of  the  apparatus,  to  prepare  likewiCe  the  oxygenated 
muriat  of  potafh,  and  to  mal-ce  experiments  orrthat  fubilance,  I  have  been  induced  to  digeft. 
the  mod;  material  facls  and  ohfervations  which  occurred,  and  to  lay  them  before  the  Society  :. 
efpecially  as  I  do  not  find  much  on  the  fubjeft  in  the  writings  of  others,  and  as  many  haic 
probably  been  deterred  from,  the  inveftigation  by  the  exorbitant  price  of  the  article,  and  b*- 
fomc  apprchenfions  of  danger  attending  It. 

A  few  experiments,  which  are  not  new,  have  been  introduced,  in  order  to  bring. undec, 
one  point  of  vie\r  the  principal  chemical  fa£ls  which  relate  to  this  fait.  I  have  given  iiv; 
moft  cafes  an  exa£t  account  of  the  quantities  of  the  different  ingredients  compofing  tha 
mixtures  ;  and  as  perfons  not  much  accuftomed  to  fuch  experiments  may  be  inclined  to 
repeat  fome  of  them^  I  would  cautio:i  them  not  to  tife  greater  quantities  than  are  here  fpecifieJy^ 
particularly  where  the  terms  violent  detonation,  explofion,,5:c.  are  employed. 

I  would  not  by  any  means  wi(h  it  to  be  undcrftood  that  1  have  cxhaufted  the  fubjefi  : 
many  more  experiments  and  much  labour  and  afTiduity  are  required,  before  the  nature  au4 
ufes  of  fo  aftive  a  fubftance  can  be  fully  afcertained. 

I  find  it  has  been  introduced  Into  medicine  with  fuccefs  ;  and  I  hope  its  good  effecls,  in. 
that  refpeft  will  not  be  fruftrated  by  the  high  price  of  the  article,  as  it  may  be  procured  at  a 
flauch  cheaper  rate  than  it  is  commonly  charged. 

I.   On  the  Preparation  of  the  Salt,  and  its  Solution  in  Water  and  the  Aiids.- 

I'indirlg  that  a  quantity  of  gas  efcaped  occafionally  from  our  apparatus  for  making  the* 
new  bleaching  liquor,  more  efpecially  when  the  fire  was  not  properly  managed,  or  when 
by  any  other  means  a  greater  quantity  of  gas  was  produced  than  the  liquor  could  abforb  y 
I  thought  it  would  be  ufeful  to  adapt  to  the  large  apparatus  a  fmaller  one,  in  which  this 
fuperfluous  gas  might  be  condenfed  ;  as  the  efcape  of  it  was  fometimes  difagreeable  to  ther 
workmen.  This  I  did  by  filling  an  earthen-ware  bottle  with  a  ftrong  folution  of  potafli  in 
water  (confifting  of  about  three  pounds  of  alkali  to  the  gallon),  which  I  found  entirely  re. 
Keved  us  from  the  difagreeable  fmell  we  frequently  experienced  before,  and  at  the  fame 
time  yielded  a  confiderable  quantity  of  the  oxygenated  muriat.  Though  the  produdion  of 
the  oxygenated  muriat  in  this  way  be  fomewhat  precarious,  depending  upon  the  manage^ 
ment  of  the  perfon  who  conduds  the  process  (it  being  the  bleacher's  intereft  to  condenfe 
the  whole  of  the  gas  in  the  liquor  he  wants  for  his  bufinefs)  ;  yet  I  think,  if  the  portion 
which  commonly  efcapes  were  thus  difpofed  of,  a  confiderable  quantity  of  this  fait  might  be 
made  by  bleachers  with  little  additional  expence,  except  what  is  incurred  by  the  purchafe 
of  the  alkali,  and  fome  more  labour  and  attention.  At  fome  of  my  firft  trials,  about  two 
years  ago,  I  found  the  gas  which  efcaped  from  the  materials  of  one  diftillation  fufficient  to 
feturate  two  gallons  of  the  alkaline  folution,  from  which  I  procured  about  fix  ounces,  and 

•  Manchcfter  Memoirs,  v«l.  v.  part  J. 

fometimes^ 


Prepay aiian  of  the  Oxyget'tated  Muri'at  of  Potafb,  igr 

Ibmetimes  more  of  the  fait,  after  being  purified  by  feveral  cryftallizations.  But  having  mads 
"fome  alteration  In  the  apparatus,  I  now  find  that  the  fame  quantity  of  alkali  may  remain 
for  three  or  four  diftlliations  before  fufficient  gas  be  furniflied  to  form  the  fait ;  except  the 
perfon  employed  be  remarkably  inattentive  to  his  duty.  I  confuler  this  as  a  valuable'  im- 
provement, tlie  making  of  the  fait  being  only  a  fecondary  objeft.  The  fait  was  chiefly 
formed  during  the  dlilillation.  The  alkali  became  warm  toward  the  latter  end  of  the 
procefs,  cfpecially  if  the  abforption  of  gas  was  very  rapid,  a  quantity  of  caloric  being  dif- 
engaged.  In  this  cafe-,  a  confulerable  part  of  the  fait  foon  cryftallized,  on  the  lixivium  be- 
hig  fet  In  a  cool  place,  and  a  great  deal  of  gas  appeared  to  efcape  ;  which  on  one  occafion  1 
colle(n:ed,  and  found  that  it  precipitated  lime  from  its  felution  in  water,  and  extingulflied 
flame  :  and  tlierefore,  though  it  had  a  flight  fmell  of  the  oxygenated  muriatic  acid  gas,  I 
believe  that  it  confided  chiefly  of  carbonic  acid,  as  the  former  occafions  no  precipitation  of 
lime  water,  which  the  latter  uniformly  does.  A  glafs  jar  containing  32  ounce  meafures 
of  this  gas,  being  left  over  water  one  night,  was  reduced  to  about  one  fourth  its  "bulk.  The 
gas  that  remained  feemed  to  contain  more  oxygene  than  the  air  of  the  room ;  two  mea- 
fures of  it,  with  one  of  nitrous  gas,  gave  1.53,  whilft  an  equal  quantity  of  common  air 
gave  i.g. 

Before  any  of  the  fait  appeared  to  be  formed  in  the  alkaline  folutlon,  I  have  conftantly 
obferved  a  quantity  of  earthy  matter  to  be  precipitated.  This  was  cai'efully  feparated  from 
rive  fait,  and,  after  being  waflied  repeatedly  in  boiling  water,  was  fufFered  to  dry  ;  but  not. 
having  examined  it  with  fufllcient  minutenefs  to  fay  what  it  is,  I  (hall  content  myfelf  atpre- 
fent  with  flating  fome  of  its  properties.  It  did  not  detonate  with  fulphur,  and  was  totally  or. 
nearly  infoluble  in  water.  The  fulphuric  acid  diflblved  it,  and  gave  evident  figns  of 
muriatic  acid,  which  appeared  to  be  flightly  oxygenated.  After  being  expofed  to  a  red 
heat  for  half  an  hour,  the  above  properties  ftill  appeared  the  fame,  except  with  the  fulphuric 
acid.  I  thought  the  gas  that  was  difengaged  had  more  of  the  fmell  of  fimple  muriatic  acid 
gas,  though  along  with  it  a  little  of  the  oxygenated  gas  might  be  perceived.  The  muriatic 
acid  did  not  appear  to  diflblve  any  of  this  fubftance,  either  before  or  after  its  calcination. 
With  the  nitrous  acid  a  ftrong  fmell  of  the  oxygenated  muriatic  gas  was  produced.  From 
a  dram  of  this  fubftance  in  an  earthen  retort  expofed  to  a  ftrong  heat,  about  fix  ouncc- 
meafurcs  of  gas  were  produced,  confifting  of  a  mixture  of  carbonic  and  azotic  gas,  the 
latter  of  which  was  in  the  greateft  quantity,  forming  by  eftimate  about  three  fourtlis  of  the 
whole. 

The  form  of  the  cryftals  that  firft  appeared  in  the  folutlon  of  alkali  were  quadrangular 
plates  :  what  were  afterwards  formed,  when  the  lixivium  became  cool,  were  needle-like,  as 
were  thofe  that  were  produced  by  fpontaneoufly  evaporating  the  remainder  of  the  ley  :  they 
appear  to  have  the  fame  property  of  detonating  as  the  firft.  Thefe  different  forms  of 
cryftals  appeared  on  diffolving  the  fait  in  hot  water,  and,  when  cold,  feparating  the  fait,  and 
fuffering  the  water  to  evaporate  fpontaneoufly. 

I  frequently  obferved,  that  unlefs  the  alkali  began  to  part  with  a  confiderable  portion  of 
gas  without  the  admifliion  of  any  from  the  apparatus,  little  or  none  of  the  oxygenated 
muriat  was  procured  ;  and  that  as  this  gas  (which  I  have  before  obferved  to  be  chiefly  the 
carbonic  acid)  efcaped,  the  cryftallizatlon  took  place,  and  increafed  or  diminiftied  according 
to  the  evolution  of  that  gas.    This  I  found  uniformly  the  cafe,  whether  mild  or  cauftic 

alkaU 


3$f2  Prepcration  and  HaiUtiiei  of  the  Oxygenated  Muriat  of  Potafj, 

alkali  was  employed.  A  given  quantity  of  the  ftrong  folution  of  potafh  appeared  to  pro- 
duce more  of  this  fait  than  the  fame  quan;;ity  of  a  folution  of  pearlalh  of  the  fame  fpecific 
gravity.    - 

The  remaining  lixivium,  on  evaporation,  did  not  yield  this  fait,  though  a  muriat  of 
potafh  was  formed,  that  appeared  to  be  confiderably  oxygenated  :  fince,  with  the  addition 
of  the  fulphuric  or  muriatic  acid,  it  became  a  very  powerful  deftroyer  of  vegetable  colours ; 
it  would  not  detonate  with  fulphur,  or  inflame  combullible  fubltances,  with  acids  ;  it  was 
very  foluble  in  water,  much  more  fo  than  tlie  muriat  firft  formed  fiom  the  fame  alkali. 

I  may  here  remark,  that  I  think  the  French  chemifls  were  fight  in  calling  the  firft  fait 
the  hyperoxygenated  muriat,  as  the  fait  laft  mentioned  is  certainly  oxygenated  in  fome  de- 
gree :  however,  in  the  following  experiments  I  fliali  ufe  the  term  oxygenated  muriat,  when 
fpeaking  of  the  fait  formed  during  the  diftiilation,  and  on  cooling  the  lixivium  after  being 
faturated  with  the  gas. 

Experimetit  I.    One  part  of  the  oxygenated  muriat  of  potafh  required  about  feventeen 
parts  of  water  at  the  temperature  of  60°,  to  diflblve  it ;  whilft  five  parts  of  boiling  water  ■ 
diffolved  two  of  the  fait.  Repeated  folutions  did  not  appear  to  injure,  but  rather  to  increafe, 
its  detonating  property.     The  cryftals  became  much  whiter  ;  and  a  quantity  of  the  earthy 
matter  before  mentioned  was  feparated  at  every  frefh  cryftallization. 

Experime?it  11.  A  quantity  of  this  fait  was  put  into  a  bottle,  and  placed  in  a  fituation 
aiuch  expofed  to  the  light :  after  being  kept  there  more  than  twelve  months,  it  die!  not  ap- 
pear to  have  loft  any  part  of  its  detonating  property.  This  fa£t  is  contrary  to  Chaptal's 
aflcrtion,  that  the  mere  imprefllon  of  light  is  fufEcient  to  decompofe  it  *. 

Experiment  III.  Water  faturated  with  this  fait  was  expofed  to  the  light  for  feveral 
months,  without  appearing  to  be  at  all  changed.  It  was  put  into  a  bottle  with  a  ground 
Hopper  and  tube,  to  which  an  apparatus  was  adapted  to  receive  any  gas  that  might  come 
over  ;  but  no  gas  whatever  was  difengaged. 

Experiment  IV.  Sixty  grains  of  fait  w,ere  fufed  by  the  heat  of  a  lamp  in  a  bottle  with  a 
ground  ftopper  and  lube.  After  having  been  kept  in  a  fluid  flate  for  about  half  an  hour,  I 
found  that  it  had  loft  two  grains  in  weight,  and  that  a  fmall  quantity  of  air  was  given  out,, 
which  proved  to  be  oxygenous  by  the  teft  of  nitrous  gas.  The  fait  which  had  been  melted 
would  ftill  detonate  with  fulphur,  &c.  The  lofs  of  weight  was,  I  am  inclined  to  think,, 
chiefly  owing  to  the  efcape  of  the  water  of  cryftallization  ;  for  the  fait  when  cool  had  loft, 
its  tranfparency. 

Experiment  V.  From  forty  grains  of  the  fait  in  an  earthen  retort,  I  procured  by  the  ap- 
plication of  heat  about  thirty-fix  cubic  inches  of  oxygenous  gas  ;  the  evolution  of  which. 
was  very  rapid,  and  commenced  as  foon  as  the  retort  became  flightly  red.  Forty  grains 
expofed  in  a  crucible  to  a  ftrong  red  heat  appeared,  from  the  mean  of.  two  experiments,  to 
have  loft  about  feventeen  grains  in  weight.  The  remaining  muriat,  being  afterwards 
thrown  into  the  fulphuric  acid,  produced  a  very  ftrong  fmeil  of  oxygenated  muriatic  acid  j 
from  which  I  inferred  chat  the  whole  of  the  oxygen  hjd  not  been  expelled  by  the  heat  j. 
'ji hence  the  oxygenated  muriat  of  potafli  may,  1  liiink,  be  ftatcd  to  contain  about  half  its 
ufeight  of  o;£ygcu  in  a  concrete  ftate. 

•  Elements  of  Chcmiflry,  i,  a  50. 

Experiment- 


Expeflmmti  with  the  Oxygenated  Muriai  of  Potajlj.  2^3 

Expenment  VI.  Strong  nitrous  acid  difengaged  the  oxygenated  muriatic  acid  from  this 
fait.  During  the  folution  of  two  or  three  grains  of  the  oxygenated  muriat  in  this  acid,  a 
•grain  or  two  of  phofphorus  was  dropped  into  the  glafs  containing  the  mixture  ;  when  a 
number  of  vivid  flaflies  appeared  in  the  liquor,  darting  forth  at  intervals  for  a  confiderable 
time.  This  is  one  of  the  moft  ftriking  experiments  I  ever  faw ;  but  a  little  caution  i$ 
ficceflary  in  performing  it,  the  phofphorus  being  fomeciines  thrown  out  of  the  mixture  *. 

Experiment  VII.  The  muriatic  acid  diflblved  this  fait,  a  great  deal  of  the  oxygenated 
acid  being  given  out.  A  few  grains  of  the  fait  added  to  an  ounce  of  the  acid  rendered  it  a 
very  powerful  deftroyer  of  vegetaWc  colours.  This  mixture  may  probably  be  ufed  with 
advantage  in  taking  ftains  of  ink,  Sec.  out  of  linen  or  cotton. 

Phofphorus  addea  to  this  acid  along  with  the  fait  did  not  produce  the  fame  effeft  as 
with  the  nitrous  acid ;  no  light  appearing,  as  in  the  laft  experiment. 

Experhnetit  VIII.  On  putting  a  little  of  the  fait  into  the  fulphuric  acid,  a  violent  crack- 
ling, or  a  great  number  of  fmail  exploGons,  took  place,  and  a  very  firong  fmell  of  nitrous 
gas  was  produced  ;  the  mixture  at  the  fame  time  afluming  an  orange  colour,  which  difap* 
peared  after  it  liad  Itood  a  fhort  time.  A  very  fmall  piece  of  phofphorus  having  been 
dropped  on  about  two  grains  of  the  fait  (previoufly  thrown  into  the  acid),  an  cxplofion  im- 
mediately took  place,  which  blew  out  a  great  part  of  the  mixture  upon  my  handj  an  ac* 
cidentthat  might  have  proved  ferious  if  I  had  not  had  water  near  me. 

Experiment  l^.  Finding  a  great  quantity  of  gas  to  be  difengaged  from  this  fait  by  the 
fulphuric  acid,  which  had  a  very  ftrong  fmell  of  nitrous  gas,  I  put  forty  grains  of  the  fait 
into  a  glafs  retort,  and  poured  upon  it  nearly  an  equal  weight  of  fulphuric  acid  diluted 
•with  water.  With  the  heat  of  a  lamp  the  gas  began  to  come  over  very  rapidly,  and  was 
received  in  a  glafs  jar  placed  in  a  bafon  of  water.  A  conGderable  portion  of  it  appeared 
to  be  abforbed  by  the  water,  which  acquired  a  yellowifli  colour.  This  colour  difappeared  on 
(landing  a  few  days,  and  a  brown  matter  was  depofited,  which  being  carefully  collected 
and  dried  weighed  one  grain,  and  appeared  to  be  manganefe  ;  for  a  little  of  it,  being  put  into 
the  muriatic  acid,  fo  far  oxygenated  it  that  it  would  deftroy  the  blue  colour  of  a  diluted 
folution  of  indigo  in  the  fulphuric  acid.  The  precipitate  before  mentioned,  that  was  firll 
produced  in  the  alkali  employed,  did  not  appear  to  have  this  efFedV.  The  quantity  of  this 
fediment  that  I  had  an  opportunity  of  colle£ling  was  fo  fmall,  that  I  could  not  try  many 
other  experiments  with  it:  indeed  I  did  not  always  fucceed  in  procuring  it;  for  I  found 
that,  unlefs  the  difengagement  of  the  gas  was  very  rapid,  but  little  of  it  could  be  ob- 
tained. 

Experiment  X.  On  two  drams  of  the  fait  in  a  glafs  retort,  I  poured  an  equal  weight  of 
fulphuric  acid  diluted  with  a  little  water,  and  adapted  the  retort  to  Woulfe's  apparatus. 
The  heat  of  a  lamp  was  applied;  and  prefently  the  gas  began  to  efcape,  and  was  abforbed 
by  the  water  in  a  confiderable  quantity  ;  to  which  it  communicated  a  yellowifli  colour, 
and  a  liquid  began  to  trickle  down  the  neck  of  the  retort  into  the  receiver.  This  had  con. 
tinned  but  a  fliort  time  before  a  violent  expIoCon  took  place,  which  broke  the  retort  and 
two  of  the  receivers  to  pieces,  together  with  feveral  other  glafles  which  were  on  the  table. 
This  was  feveral  times  repeated,  but  with  more  caution  than  before ;  and  I  always  found, 

■s  This  curious  experiment  was  firft  noticed  by  J.  Collier,  and  was  coronruaicated  bjr  him  to  the  Society 
ibinc  time  ago, 

Voi.  II,- Oct.  1798.  Q.<1  A»t 


29-4  Injlammathn  of  comhujiibh  Bodies  •uiith 

that  when  the  mixture  acquired  a  certain  degree  of  heat  an  explofion  certainly  took  placr^ 
except  the  retort  Iv.i  n  pretty  wide  neck,  and  the  neck  was  fimply  introduced  into  a  re- 
ceiver with  a  confidcrable  opening  in  it  without  any  lute;  or  put  into  water,  as  in  the  lad 
experiment :  and  even  in  this  cafe  I  would  not  advife  fo  much  of  the  fait  to  be  ufed  at  one 
time  as  is  here  mentioned.  The  fmall  quantity  of  acid  I  was  able  to  colleft  in  this  way, 
by  adapting  a  loofe  receiver,  appeared  to  be  a  weak  muriatic  acid  flightly  oxygenated  ;  it 
v/as  of  a  dilute  purple  colour,  which  difappeared  on  its  being  expofed  a  (hort  time  to  the 
light  :  a  fmall  piece  of  iron  dropped  into  it  caufed  it  to  become  tranfparent  immediately. 

It  was  a  matter  of  much  furprife  to  me,  to  find  fo  ftrong  a  fmell  of  nitrous  gas  produced 
on  dctompofing  this  fait  with  fulphuric  acid.  Now>  as  nitrous  gas  confids  of  azot  and 
o;(ygen,  fuppofinjf  tliis  to  be  nitrous  gas  (for  I  do  not  aflert  it  to  be  fo,  though  I  fhould 
think  the  im.cll  in  this  inftance  an  almoft  fuflicient  criterion),  whence  comes  the  azot  ?  At 
firft  I  thought  it  might  come  from  a  decompofition  of  the  alkaline  bafe  of  the  fait ;  as  fomc 
chemifts  h;ivc  imagined  tl:e  vegetable  alkali  to  be  con-pofed  of  lime  and  azot :  in  that  cafe-, 
I  expefted  the  reuduum  would  have  been  the  fulphat  of  lime  ;  hut  I  found  it  to  be  chiefly 
fulphat  of  potafii,  with  a  little  of  the  oxygenated  muriat  that  remained  undccompofeJ 
along  with  it.  At  prefent  I  fliall  not  hazard  any  opinion  refpefling  the  origin  of  this  ni- 
trous fmell ;  but  hope  fome  experiments  I  am  at  prefent  engaged  with  will,  if  I  can  find 
time  to  profecute  them,  throw  fome  light  upon  this  fubje£l:. 

II.  On  the  Detonatian  and  Itiflammntion  of  comhuflihle  Subjlances  -with  the  Salt  produced  by: 

FriSilon  ami  the  Jdds. 

THE  detonating  properties  of  this  fait  were  tried  with  various  fubftances  in  the  following 
experiments  :  the  different  mixtures  were  intimately  combined  by  gently  rubbing  them  ii> 
a  ftone-ware  mortar :  after  this  was  done,  one  fmart  ftroke  acrofs  the  mixtures  would  caufc 
the  whole  of  fome  of  them  to  explode  at  once,  and  others  fucceffively  by  repeating  the 
friftion.  The  fulphuric  acid  inflamed  moft  of  thefe  mixtures  of  the  fait  with  combuftibla 
fubftances  :  the  nitrous  acid  alfo  had  the  fame  effefl:  with  fome  of  them. 

Experiment  I.  ivith  Phofphorus.  Half  a  grain  of  this  fubftance  rubbed  with  the  famo 
weight  of  the  fait  produced  violent  explofion  with  flame.  I  apprehended  it  would  be 
dangerous  to  ufe  much  greater  quantities,  as  the  phofphorus  is  frequently  thrown  out  with 
violence  before  it  is  confumed.  The  fulphuric  acid  inflamed  this  mixture,  as  I  have  before 
ftated. 

Experiment  II.  tuith  Charcoal.  Two  grains  of  fait  with  one  of  charcoal  intimately  mixedi 
and  perfe£lly  dry,  produced  by  a  fmart  ftroke  a  ftrong  flame  without  much  report.  The- 
fulphuric  and  nitrous  acids  inflamed  this  mixture,  the  latter  with  moft  rapidity. 

ExperimentWi.  luith  Pit-coal.  A  grain  of  4ry  pit-coal  rubbed  with  the  fame  quantity  of 
the  fait  produced  fparks  and  fomc  fmall  reports.  With  half  the  quantity  of  coal  the  reports 
were  much  louder. 

The  fulphuric  acid  added  to  about  twenty  grains  of  the  fait  with  ten  of  the  coal,  prcH- 
duced  a  bright  red  flame  rifing  up  to  a  confiderable  height. 

Experiment  IV.  tvith  Sulphur.  A  grain  of  the  fait  rubbed  with  half  a  grain  of  fulphur 
produced  a  very  loud  report,  attended  with  flame  and  a  itrong  fmell  of  fulphureous  acid. 
When  the  fulphur  was  reduced  to  a  quarter  of  a  grain,  the  explofion  was  not  made  at  once 

as. 


the  Oxygenated  Muriai  of  Potajh.  29f 

as  before,  but  fucceflively.  When  the  proportion  of  fulphur  was  increafed  to  three  fourths 
of  a  grain,  it  produced  a  very  loud  report,  much  the  fame  as  the  firft  ;  and  the  whole  ap- 
peared to  explode  at  once.  Equal  parts  of  fulphur  and  the  fait  did  not  caufe  fo  ftrong  re- 
ports as  when  a  lefs  quantity  of  fulphur  was  employed  :  this  mixture  exploded  fucceflively. 
The  fulphuric  and  nitrous  acids  inflamed  it. 

Experiment  Y .'  luiih  SulpJiuret  of  Potajb.  One  grain  of  the  fait  rubbed  with  tlie  fame 
iveight  of  this  fubfta:ice  produced  a  very  loud  explofion  with  flame.  With  half  a  grain  of 
the  fulphuret  I  thought  the  report  fully  as  violent.  A  little  of  thefe  mixtures  melted  over 
the  fire  had  not  the  effeft  of  the  fulminating  powder  made  with  nitre.  It  only  emitted  a 
ilafh  without  any  report,  nor  was  1  able  to  produce  a  fulminating  mixture  by  varying  the 
proportions  of  the  fait,  alkali  and  fulphur.  The  fulphuric  or  nitrous  acids  dropped  on 
this  mixture  gave  a  very  ftrong  bright  flame. 

Experiment  V\.  ivith  fulphuret  of  Mercury.  {CinimbarJ)  Equal  parts  of  this  fubflance 
and  of  the  fait  detonated  fucceflively  by  frittion,  a  grain  of  each  being  ufeJ.  A  change  of 
proportion  appeared  to  weaken  the  detonating  property  of  the  mixture.  The  fulphuric 
acid  inflamed  this  mixture,  but  not  fo  rapidly  as  in  the  laft  experiment.  The  nitrous  acid 
did  not  inflame  it. 

Experiment  VII.  -with  Sulphuret  of  Jrfenic.  [Orpimeiit.)  A  grain  or  two  of  the  fait  rubbed 
with  an  equal  weight  of  this  fubflance  produced  little  more  than  a  flafh  ;  but  a  grain  of  the 
fait  with  half  a  grain  of  the  fulphuret  gave  a  ftrong  report,  though  very  little  friction  was 
ufcd.  Reducing  the  quantity  of  fulphuret  to  a  quarter  of  a  grain,  the  explofions  were 
weak  and  fuccefllve.  A  larger  quantity  of  this  mixture  than  is  mentioned  above  makes  a 
report  which  is  very  unpleafant,  with  confiderable  flame.  I  was  greatly  furprifed,  the  firft 
time  I  made  the  experiment  with  two  or  three  grains  of  the  fait  and  a  portion  of  the  ful- 
phuret, by  their  exploding  in  a  moft  violent  manner,  though  a  very  flight  fridion  had  been 
ufed.  The  fulphuric  or  nitrous  acids  gave  a  very  ftrong  flame  the  moment  they  were 
dropped  upon  this  mixture. 

Evperitnent  VIII.  <iuiih  Cotton-wool.  A  fmall  quantity  of  very  dry  cOtton-wool  was  rubbed 
with  a  little  of  the  fait ;  no  detonation  took  place.  The  wool  was  afterwards  dropped  into 
the  fulphuric  acid,  and  took  fire  immediately  ;  but  the  nitrous  acid  would  not  inflame  it. 

Experiment  IX.  tvith  Loaf-fugar.  One  grain  of  this  fubftance  rubbed  with  two  of  the 
fait  gave  a  number  of  fucceffive  reports.  The  fulphuric  or  nitrous  acids  dropped  on  thi* 
mixture  inftantly  produced  a  ftrong  flame  afcending  to  a  confiderable  height. 

Experiment  X.  with  fixed  and  ejfential  Oils.  A  few  drops  of  fpermaceti  oil  rubbed  with  a 
grain  or  two  of  the  fait  produced  a  number  of  loud  reports.  The  fulphuric  acid  inflamed 
this  mixture  •,   the  nitrous  acid  did  not. 

Olive  oil,  the  effential  oils  of  rofemary,  juniper,  cloves,  carraway,  anifeed,  cinnamon, 
nutmeg,  amber,  mint,  and  eflence  of  lemon,  were  rubbed  with  the  fait :  all  of  them  de- 
tonated fucceflively,  and  fuch  of  the  mixtures  as  were  tried  took  fire  with  the  fulphuric  acid. 
Experiment  XI.  ivith  Spirit  of  Turpentine.  A  few  drops  of  fpirit  of  turpentine  rubbed 
with  a  little  of  the  fait  detonated  in  much  the  fame  manner  as  the  fubftances  ufed  in  the 
laft  experiment.  The  fulphuric  acid  dropped  on  this  mixture  produced  a  ftrong  flame,  with 
a  cloud  of  very  black  fmoke. 

Experiment  XII.  with  Camphor.    A  little  of  this  fubftance  on  being  rubbed  with  a  grain 

Q.q  2  9f 


3^6  Itifammaikn^  isfc.  nvith  Oxygfffafcd  Murlat  of  Bofajh, 

of  the'  fait  prodDced  a  number  of  fucccflive  detonations.     The  fulpburic  acid  produced 
fhi'rr.e  with  fome  explofions. 

'Mxp^'hmut  XIII.  ivhh  Rofni.  One  part  of  this  fubftance  wiih  two  parts  of  the  fait  de- 
tonated fucceffively  when  well  rubbed  together,  llie  fulphuric  acid  inflamed  this  mixture;^ 
but  the  nitrous  ac'wl  did  nor. 

Experiment  XIV.  loiih  Gitm-Ai-nl'ic.  The  aetonations  M-ere  very  flight.  It  was  mixed 
with  twice  its  weight  of  the  fait.  The  fulphuric  acid  fet  fire  to  the  mixture,  but  the  ni* 
trous  acid  would  not. 

Experment  XV.  iv\th  Priijfian  Blue.  No  detonations  whatever  were  produced  hf 
friftion,  nor  did  the  acids  inflame  a  mixture  of  this  fubftance  with  the  fait*. 

E.rperiment  XVI-  nvith  Indigo.  Half  a  grain  of  fine  Spanifli  indigo  rubbed  with  a  graia 
of  the  fait  detonated  fucceflivefy,  like  the  mixture  with  roGn  or  gum.  The  fulphuric  acid 
inflamed  this  mixture,  but  the  nitrous  acid  did  not. 

Experlmtnt  XVII.  •with  Elher.  A  few  drops  of  ether  on  about  two  grains  of  the  fait 
rubbed  to  a  very  fine  powder  produced  no  detonation  by  friifiion.  The  fulphuric  or  ni- 
trous acids  poured  fuddenly  upon  it  produced  flame. 

Experiment  XVIII.  luith  Tron-fiVings.  Thefe  alone  rubbed  with  the  fait  produced  no  de- 
tonation by  fimple  friftion  ;  but  two  grains  of  the  fait,  one  grain  of  iron-filings,  and  half 
a  grain  of  fulphur,  being  well  rubbed  together,  about  a  quarter  of  a  grain  of  this  mixture  ex- 
ploded violently  with  friftion.  The  fulphuric  acid  added  caufed  a  few  fparks  to  appear  \ 
but  the  nitrous  acid  did  not  produce  any.  Varying  the  above  proportions  did  not  appear  to 
improve  the  detonating  property  of  the  mixture. 

Experiment  XIX.  ivith  Aurum  Mufivum.  Equal  parts  of  this  fubftance  and  of  the  fait 
detonated  ftrongly  with  flame,  on  being  rubbed  together  in  an  iron  mortar :  a  very  flight 
fri£lion  was  necefl"ary.  The  fulphuric  acid  gave  a  fmall  flame,  but  with  the  nitrous  I  could 
not  procure  any. 

From  the  foregoing  experiments  I  think  we  may  venture  to  conclude,  that  the  oxy- 
genated muriat  of  potafli  is  equally  harmlefs  as  common  nitre  ;  except  it  be  brought  into  an 
intimate  union  with  fomething  that  has  a  greater  aflSnity  with  one  of  its  conftituent  parts, 
than  exifts  between  thofe  parts  when  combined  in  the  fait,  and  that  fome  combuftiible  fub- 
ftance be  prefent :  but  its  oxygen  being  fo  eafily  dlfengaged  renders  a  little  caution  necef- 
fary ;  and  as  the  fulphuric  or  nitrous  acids  feem  fo  readily  to  inflame  many  of  the 
mixtures,  I  would  not  advife  any  perfon  to  make  more  of  them  than  is  neceflary  for  imme- 
diate experiment.  This  precaution  may  prevent  any  unpleafant  circumftance  from  acci- 
dental mixture  with  the  acids,  which  appear  to  difengage  a  great  part  of  the  oxygen  almoft 
inftantaneoufly. 

I  fhall  not  fay  much  about  the  theory  of  thefe  detonations,  none  of  the  foregoing  experi- 
ments having  been  fo  carefully  conduced  as  to  determine  accurately  what  changes  took 
place ;  yet  I  think  we  may  attempt  to  explain  fome  of  them  in  the  following  manner :  With 
phofphorus  the  oxygen  feems  to  combine,  and  form  phofphoreous  acid  gas,  or  phofphoric 
acid  ;  with  fulphur,  the  fulphureous  acid  gas,  or  fulphuric  acid,  according  to  the  rapidity  of 

*  Chaptal  (Elements  of  Chemiftry,  vol.  ii.  page  377 J  fiys,  "  Pruflian  blue  takes  fire  more  eafily  than  ful- 
^ur,  and  eletopatts  ftrongly  with  the  oxygenated  muriat  of  potafli.  (Quaere,  Did  he  not  make  uie  of  indigo 
Iwr*?) 

the 


DetonaiionSt  £s*^. — Natural  HiJ!ory  of  Gutana.  7gj 

the  combuftion  ;  with  charcoal  and  other  vegetable  fubftances,  the  carbonic  acid  ;  with  ful- 
phuret  of  arfenic  there  may  be  fulpureous  acid  gas  and  arfenic  acid  produced. 

The  fudden  produftion  of  gas  ftriking  the  furrounding  air,  is  moft  probably  the  caufe  of 
the  loud  reports  produced  by  fri£lion,  &c.  agreeably  to  the  conclufions  of  Berthollet ;  and 
the  muriatic  acid  may  remain  combined  with  the  potafti,  and  a  portion  of  the  combuftiblc 
fubflance  employed:  but,  when  the  fulphuric  or  nitrous  acida  are  ufed,  the  muriatic  acid  is 
certainly  difeiigaged. 

Since  the  above  experiments  were  made,  I  have  found  that  a  paper  has  been  rea4  before 
the  National  Inftitute  of  Paris,  On  detonation  by  concuffion,  by  Citizens  Fourcroy  and 
Vauquelin  *.  They  there  mention  fome  of  the  mixtures  1  have  defcribed,  and  their  in- 
flammation with  the  fulphuric  acid.  They  likewife  notice,  that  very  loud  reports  and 
fparks  were  produced,  on  a  very  fmall  quantity  of  different  mixtures  being  ftruck  with  a' 
hammer  on  an  anvil.  This  on  trial  I  found  to  be  the  cafe;  and  a  little  cotton-wool  well 
impregnated  with  the  fait  being  ftruck  in  that  way  immediately  took  fire.  But,  to  get  this^ 
to  fucceed,  the  fait  and  crftton  fliould  be  perfeftly  dry :  this  is  a  neceflary  precaution  [n  all 
experiments  on  the  detonating  property  of  this  fait  by  fridlion,  &c.  In  the  paper  abovfr 
alluded  to  it  is  ftated,  that  fugar,  the  gums,fixed  and  volatile  oils,  alcohol  and  ether,  do  not 
detonate  or  take  fire  by  fimple  trituration :  but  the  experiments  I  made  feem  not  to  agree 
with  this  afTertion  ;  for  all  the  above  fubftances  that  I  tried,  except  ether,  detonated  either 
more  or  lefs,  on  rubbing  them  brifkly  in  a  ftone-ware  mortar;  fome  of  them  required  to  be 
intimately  mixed,  as  fugar  and  gum  ;  but  others  produced  very  loud  reports,  as  when  fixed 
and  efTential  oils  were  ufed. 


IV. 

Obfervatlons  6n  the  Natural  Hijlory  of  Guiana.  In  a  Letter  from  WiLLIAM  LoCTlEADr 
Efq.  F.R.  S.  Edin.  to  the  Rev.  Dr.  Walxer,  F.  R.  S.  Edin.  Regius  Profejor  of  Natural 
Htflory  in  the  Univerfty  of  Edinburgh  f . 

Dear  Sir, 


A 


LLOW  me  at  prefent  to  trouble  you  with  a  few  general  obfervations  on  natiral 
hiftory,  which  I  had  an  opportunity  of  making  while  on  a  botanical  excurlion,  with  my 
friend  Mr.  Anderfon,  to  the  Dutch  colony  of  Demerary,  Guiana  is  a  country  but  little 
known  in  Europe,  though  its  animals  and  vejjetables  have  added  confiderably  to  the  cata- 
logue of  natural  productions.  It  is  not,  however,  the  organic  kingdom  which  I  mean  at 
prefent  to  touch  upon  ;  all  I  aim  at  is,  to  give  you  fome  idea  of  the  face  of  the  country,,  as 
leading  to  the  knowledge  of  its  formation  and  prefent  ftate.  It  is  not  a  field  for  the  mine- 
ralogift,  as  its  interior  is  unexplored.  But  to  the  geologift,  who  wifhes  to  trace  revolutions 
of  the  lateft  date,  it  is  not  unintercfting  to  contemplate  fuch  a  recent  and  fingular  country 
as  Guiana. 

I  need  not  inform  you,  that  under  Guiana  is  comprehended  all  the  coaft  of  South  Ame» 


•  Annales  de  Chimie,  torn.  xxi.  p,  ^35.   Nicholfon's  Chemical  Journal,  i.  p.  169. 
f  Edinburgh  Traniafiions,  iv. 


(ica^ 


298  On  the  Natural  Hijory  of  Gu'mna. 

rica,  from  the  Amazons  to  the  Oroonoko  ;  that  it  trends  nearly  N.  W.  and  S.  E. ;  that  if 
is  in  genera!  a  very  low  and  flat  country,  efpecially  the  Dutch  or  wefternmoft  part  of  it; 
and  that  it  is  watered  by  feveral  rivers  and  creelcs,  which  rife  in  a  chain  of  mountains 
running  nearly  E.  and  W.  and  dividing  Guiana  from  the  inland  parts  of  South  America, 
which  form  the  banks  of  the  Amazons  and  its  numerous  branches. 

Coajl. — No  coaft  can  be  more  eafy  to  make  tlxan  that  of  Guiana.  The  changed  colour 
of  the  water  indicates  foundings  long  before  you  make  the  land,  and  you  may  run  on  in 
feven  fathoms  before  you  can  difcover  it  from  the  deck.  The  bottom  is  at  that  diftance  a 
foft  mud.  All  along  the  coaft  near  Demerary,  you  have  only  about  two  fathoms  at  a  good 
league  from  the  (liore  ;  to  leeward  of  Efiequebo,  it  deepens  flill  more  gradually.  In  Hand- 
ing off  or  on  five  or  fix  miles,  you  will  hardly  deepen  or  (hallow  the  water  as  many  feet. 
When  a  high  fea  fets  in  upon  fuch  a  coaft,  it  is  eafy  to  conceive  that  at  a  very  confiderable 
diftance  from  the  land  it  muft  be  affefted  by  the  bottom.  The  interval  betwixt  wave  and 
wave  becomes  more  diftindl.  As  they  roll  on  in  fucceffion,  the  lower  part  is  retarded,  tl:e 
uppcrfurface  accelerated:  each  billow  of  courfe  becomes  fteeper  and  more  abrupt,  till  at  laft 
it  gradually  ends  in  a  breaker,  when  it  has  come  to  the  depth  of  only  a  few  feet.  Thefe 
rollers  as  they  are  called  are  the  dread  of  feamen,  efpecially  betwixt  Efiequebo  and  Po- 
nieroon,  where  the  water  is  (hallow,  and  the  bearing  of  the  coaft  very  much  north  and  fouth, 
and  expofes  it  fully  to  the  a£tion  of  the  trade  winds.  In  fmall  craft,  thofe  acquainted  with 
navigation  do  not  hefitate  to  run  along  the  coaft,  even  among  the  rollers  themfelves  ;  but 
'■tlTels  drawing  from  eight  to  twelve  feet  water,  efpecially  if  the  fwell  be  heavy  and  it  falls 
calm,  can  hardly  get  oS.  If  anchor  and  cables  fail,  they  drift  on  till  they  are  faft  in  the 
mud,  and  there  they  will  continue  fometimes  for  weeks  together  before  they  go  to  pieces. 
The  fea  water  becomes  exceedingly  thick  and  muddy  within  a  few  leagues  from  the  coaft 
of  Demerary,  as  much  or  more  fo  than  the  Thames  is  at  London.  A  ftranger  would 
naturally  take  this  for  the  difcharge  of  large  flooded  rivers  after  a  rainy  feafon.  By  and  by 
I  (hall  explain  the  true  caufe  of  it. 

On  approaching  the  continent  of  South  America,  a  change  on  the  face  of  the  (ky  will 
ftrike  the  attentive  obferver.  The  clouds  become  lefs  diftin£l  from  each  other,  and  the 
intervals  between  them  lefs  clear.  They  are  blended  into  one  another  as  it  were,  and 
fuffufed  more  generally  over  the  atmofphere.  They  appear  to  be  furchargcd  with  vapour, 
•r  toliave  a  ftronger  difpofition  to  depofit  it. 

There  is  a  particular  prevailing  appearance  of  the  heavens  within  the  tropics,  when  you 
are  at  a  diftance  from  continents  or  very  high  iflands,  which  has  fo  often  ftruck  me  that  I 
wonder  it  has  not  been  taken  notice  of.  I  call  it  a  tropical  fky,  and  thus  defcribe  it.  The 
clouds  in  fine  weather  are  in  a  fingle  feries  or  ftratum,  failing  away  regularly  with  the  trade- 
winds.  They  are  fmall,  and  diftindlly  feparated  from  each  other.  The  intervals  or  fky 
above  them  of  a  clear  azure.  The  lower  furface  of  the  clouds  is  perfedly  horizontal.  As 
the  temperature  is  commonly  very  equal  over  the  fea,  the  condenfation  takes  place  every 
wbere  at  an  equal  height  from  the  furface  of  the  water.  In  the  clouds  that  are  over  head 
you  cannot  indeed  perceive  this  ;  but  it  becomes  more  and  more  vifible  as  the  eye  recedes 
from  the  zenith.  The  lower  limb  of  each  diftant  cloud  appears  perfeclly  level  and  well 
defined,  brighter  than  the  fuperincumbent  part.  At  a  diftance  nothing  is  to  be  feen  but 
thefe  limbs  clofer  and  clofer  in  gradation,  one  behind  the  other ;  and  the  whole  horizon 

roun4 


On  tie  Natural  Hijlory  of  Guiana.  igg 

round  refembles  the  roof  of  a  ftage  with  an  infinity  of  half  dropt  cuftalns  as  far  as  the  eye 
can  reach.     In  two  voyages  from  Europe,  I  have  met  with  this  tropical  fky  as  far  north  as 
Cape  Finifterre.     It  came  with  a  fair  wind,  which  continued  with   us  like  a  regular  trade 
wind,  accompanied  with  the  fame  appearance  of  the  clouds  till  we  made  the  Weft  Indies. 
In  running  down  the  trade  winds,   every  one  has  an  opportunity  of  'verifying  this  defcrip- 
tion,   and  muft  be  ftruck  with  tlie  beauties  which  this  (ky  prefents  at  the  fetting  of  the  fun. 
The  inliabitants  of  the  lower  iflands  may  alfo  be  well  acquainted  with  it.     In  the  higher 
ones,  the  attradlion  of  the  mountains  ever  forms  fets  of  clouds  of  other  appearances,  as  ' 
being  produced  by  other  caufes.     With  our  prefent  knowledge  of  meteorology,  hardly  any 
other  caufe  can  be  affigned  for  the  phenomena  above  mentioned,  than  the  conftant  equal 
temperature  that  every  where  prevails  on  the  intertropical  feas.     One  analogous  faft  how- 
ever may  be  mentioned  ;  the  exceeding  fmall  range  of  the  barometer  in  tlie  torrid  zone. 
Does  the  fame  caufe  regulate  fo  exa£lly  the  height  of  the  clouds,  and  maintain  the  uniform 
fufpenfion  of  the  mercury  ?  We  might  almoft  fufpeft  it  did,  were  it  not  well  known  that 
the  barometer  varies  as  little  upon  continents,  and  in  the  vicinity  of   mountains  in  thefe 
regions  as  elfewhere,  though  the  condenfation  of  vapours  is  in  fuch  cafes  much  more  irre- 
gular.    Upon  the  continent  you  will  frequently  obferve  this  tropical  Iky  alfo,  efpecially  in 
fine  fettled  weather ;  but  much  more  commonly  you  will  find  the  Iky  there,   and  even  be- 
fore you  make  the  coaft,  covered  with  heavy  large  dark  clouds  in  fome  places,  and  in  others 
at  a  greater  height,  the  ferene  dappled  fky  fo  often  feen  in  Europe. 

Winds. — The  trade  -zmW  generally  prevails  all  the  day  long,  and  on  the  fea  coaft  feldora. 
fails  even  at  night ;  but  in  lefs  than  fifty  miles  up  the  river  it  is  a  dead  calm  at  night,  and 
the  breeze  is  not  able  to  penetrate  fo  far  till  towards  noon.  Still  farther  up  we  had  whole 
days  of  a  flark  calm,  and  the  heat  very  intenfe. 

Dews,  fogs  and  temperature. — The  dews,  following  the  law  which  they  generally  obferve,, 
are  very  heavy  when  and  wherever  there  is  but  little  wind,  and  the  hotter  the  day  and  even- 
ing they  fall  the  more  copioufly  ;  they  were  of  courfe  more   abundant  up  the  river  than 
near  the  fea-coaft.     The  exhalations  in  the  day-time  from  a  hot  and  mifty  country  covered 
with  vegetables  being  very  great,  the  condenfation  occafioned  by  the  abfencc  of  the  fun  and 
the  cold  accompanying  that  condenfation  are  in  proportion.     Near  the  coaft,   the  diurnal 
difference  of  temperature  is  but  trifling,  the  conftant  trade -wind  preferving  in  the  air  nearly 
the  fame  medium  of  heat  as  in  the  body  of  the  ocean  ;  but  far  up  the  river  the  range  of  the 
thermometer  was  very  great.     1  he  heat  of  the  day  was  intolerable.     In  the  fliade  it  was 
frequently  above  90".     This,  when  there  is  no  breeze,  forces  you  into  the  woods  for  flielter. 
Towards  evening  it  cools  ;  during  the  night  the  cold  increafes,  and  is  greateft  about  five 
in  the  morning.     The  thermometer  would  then  be  from  72°  to  74°.     The  body  of  tha 
river  being  large  enough  to  retain   its  heat,  the    evaporation  goes  on  from  its  furface 
through  the  night,  and  is  condenfed  into  thick  fog,  which  hangs  over  it,  and  is  feldom  dif- 
perfed  before  eight  or  ten  next  day.     While  the  air  was  as  above  in  the  morning  at  72°,. 
the  water  along  fide  gave  80°  to  83%  and  feldom  rofe  two  degrees  higher  at  noon.     We 
had  an  opportunity  of  verifying  an  obfervation  made  by  the  few  inhabitants  who  live  far  up 
the  river  Demerary,  that,  when  it  feels  very  cool  in  the  morning  before  day-break,  they 
are  fure  of  fine  weaiher ;  when,,  on  the  contiary,  it  feels  warm,  they,  expes^  rain.     ThejR 

fleep, 


•goo  t5«  the  Natural  Hijlory  if  Gulatia. 

•fleep  in  hammocks,  and  the  houfes  they  have  are  pervious  enough  to  the  air  ;  fo  they  arii 
fenfib'y  affected  by  any  change  in  its  temperature. 

Seafoiis. — As  to  the  feafons,  it  is  not  an  eafy  matter,  from  the  accounts  given  by  the 
colonifts,  to  afcertain  them  exa£tly.  All  feem  to  agree,  that  fince  cultivation  has  been  fome- 
what  extended  they  are  not  fo  regular  as  before  ;  that  the  dry  feafon  encroaches  on  the 
rainy,  and  that  during  the  latter  they  have  often  feveral  dry  days  in  fucceffion.  1  he  ac- 
count given  by  Dr.  Bancroft  was  the  one  generally  allowed ;  that  it  is  dry  about  the 
equinox,  and  rainy  about  the  folfticcs ;  that  of  confequence  the^  have  two  wet  and  two  dry 
feafons  every  year.  We  thought  it  difficult  to  reconcile  this  with  the  account  given  of  the 
feafons  of  other  countries  in  firailar  climates,  and  with  what  nftually  takes  place  in  the 
Carib  iflands.  I  will  give  you  my  ideas  on  the  fubjecl.  It  is  within  the  tropics  a  very  gene- 
ral rule,  that  the  vicinity  of  the  fun  brings  the  rainy  feafon.  To  the  northward  of  the 
line,  therefore,  this  muft  be  our  furamer  months.  It  is  aiiother  invariable  law,  that  as  in 
lunar  influences,  fo  in  the  change  of  feafons  produced  by  the  fun,  fome  time  is  necefTary 
after  the  maximum  of  the  caufe  to  produce  the  full  cffeci.  The  highed  tides  are  not  till 
two  or  three  days  after  the  full  and  change.  The  greateft  heat  of  the  day  is  tv/o  hours 
afternoon,  and. the  hotted  months  in  Europe  are  July  and  Auguft,  not  June,  when  the 
fun  is  highcft.  Among  the  Weft  India  iflands  the  full  effeft  of  the  fun's  vicinity  is  ftill 
later.  1  have  found  Auguft,  and  more  efpecially  September,  to  be  the  liotteft  months  in 
the  year,  and  they  are  accordingly  the  height  of  tHe  rainy  feafon.  It  begins  thus  :  No 
fooner  has  the  fun  come  to  the  northward,  and  begun  to  be  vertical  among  the  iflands  in 
April  and  May,  than  his  force  is  felt,  the  (ky  is  more  difturbed,  the  wind  is  more  frequent- 
ly from  the  fouthward  and  in  fqualls,  and  now  and  then  there  are  heavy  fliowers.  In 
June  the  fame  effefts  continue,  and  increafe  in  July,  when  the  proper  rainy  feafon  may  be 
faid  to  begin,  and  continues  in  force  more  or  lefs  till  the  middle  of  O£lober.  Auguft  and 
September,  with  part  of  July  and  Oclober,  when  thefe  effefts  are  at  their  greateft  height, 
are  ftyled  the  hurricane  months,  and  by  the  French  I'hivernage.  During  them  the  full 
force  of  the  great  luminary  which  diftributes  light  and  life,  however  neceffary,  feems  fome- 
times  too  much  for  nature.  She  is  oppreffed  and  fickens  ;  her  refpiration  is  difordered  by 
intenfeheat ;  fometimes  calms,  fometimes  heavy  fqualls;  the  agitated  elements  vent  them- 
felves  in  lightning,  with  thunder  and  torrents  of  rain,  or  are  fometimes  thrown  out  into 
thofe  horrid  convulfions,  hurricanes,  which  feem  to  threaten  inftant  diflblution.  Guiana  is 
happily  free  from  thefe  fcourgesof  the  Antilles.  Their  force  has  lately  been  partially  felt 
at  Tobago,  which  was  thought  beyond  their  reach.  In  Trinidad,  the  greateft  ftorms  they 
have  hitherto  experienced  do  not  deferve  the  name  of  hurricanes ;  and  to  the  fouthward  on 
the  main  of  America  they  are  utterly  unknown.  The  difference  then  between  Guiana  and 
the  iflands  is  this :  In  the  former,  the  rainy  feafon  fets  in  earlier,  as  indeed  the  fun  is 
fooner  vertical.  Their  principal  rains  are  in  the  end  of  April,  in  May,  June  and  July, 
They  are  alfo  fooner  over ;  for  Auguft,  September  and  Odlober,  and  I  believe  part  of 
July,  arc  commonly  fair  wcatlier.  But  again  November,  in  part  December,  January  and 
February,  reckoned  dry  months  among  the  iflands,  are  in  Guiana  a  fecond  rainy  feafon. 
The  caufe  of  this  I  take  to  be  as  follows :  North-eafterly  winds  prettty  ftiff,  cold  and  bleak 
comparatively  in  thefe  climates,    are  frequently  among  the  iflands  during  the  winter 

monilji. 


Oft  the  Natural  H'ljlory  of  Guiana,  3OI 

ibontlis.  They  are  well  known  by  the  name  of  Norths.  They  are  -often  accompanied 
with  rain ;  but  Ft  is  not  very  heavy,  nor  thouglit  of  confequence  enough  to  give  the  denomi- 
nation of  a  rainy  feafon.  Thefe  winds  virc  know  to  reach  as  far  as  the  coaft  of  Guiana; 
and  there  I  have  reafon  to  believe  they  are  productive  of  more  rain  than  in  the  iflands. 
The  face  of  a  large  continent,  and  its  effects  upon  the  atmofphere,  may  very  probably 
make  them  give  up  more  of  their  humidity  than  they  do  among  the  Antilles,  though  at 
the  fame  time  their  force  and  bleaknefs  may  not  be  fo  much  felt.  If  this  conje£lure  hits 
the  truth,  the  following  ought  to  be  the  corollaries,  and  are  left  to  future  obfervation  : — In 
this  rainy  feafon,  when  the  fun  is  near  the  fouthern  folftice,  their  rains  will  be  with  pretty 
fteady  northerly  breezes  on  the  coaft.  They  may  be  of  longer  continuance  at  a  time,  but 
they  will  not  be  fo  heavy  as  thofe  of  funimer,  and  they  will  be  chiefly  on  the  fea-coaft,  and 
probably  will  not  extend  a  great  way  up  the  country.  It  remains  even  a  query  with  me, 
whether  the  rain  that  accompanies  the  norths  among  the  iflands,  efpecially  thofe  mod  re- 
mote from  the  line,  be  not  generally  in  a  greater  proportion  than  is  commonly  fuppofed.* 

Country. — I  will  now  endeavour  to  give  you  fome  idea  of  the  face  of  the  country. 
Though,  as  is  well  known,  Guiana  is  flat  and  fwampy,  yet  it  aftbrds  to  the  attentive  eye  an 
Interefling  variety.     The  fea- coaft  is  little  if  at  all  raifed  above  the  level  of  high  water, 
and  is  continued  at  this  level  for  many  miles  inland.     It  is  properly  an  iramenfe  woody 
fwamp,  never  dry  in  the  drieft  feafon,  covered  with  feveral  feet  of  water  in  the  wet.    Next 
tlie  (hore,  as  far  as  the  brackifli  water  extends,  it  is  covered  with  mangrove^,  which  grow 
to  a  conGderable  height  and  form  a  thick  (hade.     They  are  elevated  on  their  branchy  in- 
termingled roots  from  the  bare  wet  clay  or  mud,  on  which  there  is  fcarcely  one  herb  or 
plant,  but  which  feems  to  be  all  in  motion  from  the  prodigious  number  of  crabs   whicli 
make  their  holes  in  it.     Further  on,  when  the  under  water  is  frefli,  you  meet  with  a  ne\f 
fet  of  vegetables,  principally  fmall  trees,  which  from  their  fituation  are  obliged  to  adopt 
the  habits  of  mangroves,  having  the  bottom  of  their  trunks  fupported  three  or  four  feet 
above  ground  by  their  ramified  roots.     Several  climbing  plants   are   mixed  with  them. 
Arunis  in  great  variety  and  profufion  emerge  from  the  water,  or  embrace  the  ftems  of  the 
trees  j  and  feveral  broad-leafed  plants  of  the  hexandria  and  triandria  clafles  aflTift  the  aruni* 
in  forming  an  herbage.     In  all  this  low  part  of  Demerary  there  is  not  one  tree  of  a  large 
fize,  nor  among  them  all  above  two  or  three  fpecies  which  can  be  applied  to  ufe  as  timber. 
Proceeding  ftill  up  the  river,  its  banks  are  found  generally  to  raifc  themfelves  above  the 
level  of  the  water ;  and  when  you  have  gone  up  one  tide  (betwixt  twenty  and  thirty 
miles),  they  are  fo  high  that  there  is  no  farther  occafion  for  dams  to  keep  the  plantation! 
from  being  overflowed  at  high  water,    as  below  :  canals  or  ditches  are  fuflicient  to  drain 
the  land,  which  is  ftill  perfeftly  flat.      The  trees  are  here  different  in  fpecies  and  larger  ia 
fize  than  below,  and  the  woods  are  much  more  pradlicable.     As  they  are  drier,  the  ground 
has  acquired  a  regular  fort  of  furface,  and  there  is  neither  that  plexus  of  roots  nor  the 
fame  number  of  vines  (the  common  name  in  the  Weft  Indies  for  all  climbrng  plants)  to 
entangle  thofe  who  choofe  to  traverfe  them.     The  foil  here  is  generally  a  ftjfF,  cold,  reddilh 
clay,  tnixed  a -top  with  a  portion  of  vegetable  mould. 

The  fand-hills  prefent  to  the  admiring  eye  a  fcene  very  different  from  what  it  had  beea^ 
accuftomed  to  btlow.  The  hrft  you  meet  with  upon  t!ie  Demerary  is  upwards  of  thirty 
miles  from  the  mouth  of  the  river,  and  on  the  right  hand  afcending,  or  on  its  weftcrn  (hore. 

Vol.  II.— Oct.  1758,  Rr  There 


f 


^oa  Oti  the  Natural  Hj/lory  of  Guiana. 

There  are  of  them  further  down  in  the  coutitry,  but  not  clofe  to  the  river  fide.  This  one- 
is  the  extremity  of  a  ridge  which  extends  to  the  weft  ward  feveral  miles.  As  you  aicen^ 
the  river  you  meet  with  many  more  of  the  fame  kind  on  both  fides,  whofe  direction  feems 
likewife  to  be  eaft  and  weft,  or  nearly  at  right  angles  with  the  average  courfe  of  the  ftream. 
They  vary  from  50  to  ico,  150  or  200  feet  of  perpendicular  height  above  the  level  of  the 
river  and  the  intervening  flat  country.  Their  breadth  and  extent  vary  fometimes  only  a 
few  hundred  paces,  fometimes  many  miles.  Their  length  is  great ;  with  fome  interrup- 
tions, 1  have  reafon  to  believe  they  are  generally  continued  from  one  fide  of  the  colony  to 
the  other,  only  interfered  in  different  places  by  the  rivers  and  their  branches.  They  confill 
of  a  pure  filiceousfand,  fo  white  that  it  da-^zles  the  eyes,  commonly  fine-grained  and  loofe, 
but  not  unfrequently  mixed  with  littlt;  ftrata  of  coarfer  pebbles,  mofily  quartz,  and  fome- 
times concreted  into  a  proper  fand-flone.  In  the  laft  cafe,  a  black  or  rcddifh"  tinge  is  in 
many  cafes  communicated  to  it  from  clay,  decayed  vegetables,  or  other  extraneous  matter. 
There  is  no  regular  ftratification  to  be  found  in  it,  more  than  what  is  common  to  all  funds 
the  produce  of  depofitions  oftiifferent  dates;  and,  as  they  are  of  different  materials,  thicker 
in  one  place,  thinner  in  another,  fometimes  horizontal  but  oftener  inclined,  and  convex 
or  concave  according  to  circumftances.  We  could  meet  with  no  appearance  of  (hells  or 
other  marine  produftions,  but  in  a  few  places  pieces  of  broken  vegetables  buried  in  the 
fand  where  it  was  concreted.  They  were  black,  as  all  the  foffil  vegetables  that  I  have  ever 
feen  in  (\md-ftone.  Upon  and  by  the  fides  of  the  fand-hills  grows  the  moft  valuable  timber 
of  thefe  colonies.  The  trees  there  are  of  a  good  fize,  and  very  clear  of  obllruding  under- 
woods or  vines.  The  wallabba  (parivoa  grandiflora  of  Aublet) ;  the  fipiri  or  green-heart 
(a  new  fpeciesof  laurel);  the  coumarou  or  tonqusebean  tree,  coumarouna  odorata  of 
Aublet ;  the  mora,  valuable  for  boat  timbers  ;  and  many  others  whofe  wood  is  equally  hard 
and  beautiful. 

Continuing  to  afcend  the  river,  the  fand-hills  become  rather  more  frequent  i  but  the  in- 
tervals ftill  remain  a  perfeifl  flat,  though  now  feveral  feet  above  the  level  of  the  ftream, 
and  the  foil  is  ftill  a  ftiff  clay.  Hitherto  the  river  is  deep  all  over,  generally  from  two  to  fiv« 
fathoms ;  the  bottom  is  mud  or  clay,  and  the  (hores  on  either  fide  at  low  water  covered 
with  ooze.  About  1 30  miles  up,  however,  or  juft  before  it  begins  to  fliallow,  the  bottom 
is  covered  with  banks  of  a  hard  white  or  brown  fand.  It  was  a  problem  for  fome  time, 
whence  all  this  fand  originated  in  fuch  a  country.  It  was  foon  folved.  Leaving  here  the 
veflel  that  had  hitherto  carried  us,  we  proceeded  in  a  canoe  ;  and  at  about  160  or  170 
miles  diftance  from  the  mouth  of  the  river  we  met  with  the  firft  proper  hills  of  folid  mate- 
rials. The  neareft  to  us  was  a  rock  of  granite  pvojed"ling  into  the  ftream,  whofe  dire£lion 
it  gave  a  change  to  at  this  place ;  and  it  ferved  for  a  landing  place  to  the  higheft  piece  of 
cleared  land  upon  the  river  not  to  the  poft-holders.  It  was  part  of  a  low  ridge  of  the 
fame  flone  which  croffed  the  country  probably  to  Berbia  or  beyond  it,  and  was  fucceeded 
by  many  other  feries  of  hills  more  inland,  and,  as  far  as  we  could  examine  them,  of  the  fame 
materials.  The  granite  was  both  of  the  red  and  the  gray  kinds,  but  chiefl^y  of  the  latter. 
A  number  of  feams  or  dikes  crofl'ed  it  here  and  there  in  all  direi^ions,  not  diftincflly  feparate,, 
but  firmly  united  to  the  reft,  making  as  it  were  but  one  body  with  it,  and  confifting  of  the 
fame  materials  differently  modified.  Their  component  parts  were  generally  fmaller;  they 
were  more  compaft  and  clofer  in  the  texture  than  what  furrounded  them ;  and  where  they 

had 


On  the  Natural  HiJ»ry  of  Guiana.  303 

had  been  equally  expofed  to  the  aftion  of  the  weather,  they  appeared  to  have  borne  it  much 
better  than  the  furrounding  granite.  The  origin  of  the  fanJ  was  now  accounted  for.  This 
ftonc,  in  fome  cafes  exceedingly  firm  and  durable,  is  in  others  very  liable  to  decay  ;  and  the 
wafli  of  thefe  enormous  chains  of  hills  was  able  to  furnifh  abundance  of  fuch  fand  as  we 
had  met  with  below.  The  granite  afforded  many  varieties ;  indeed,  every  fliade  from  large 
and  diftinft  grained  to  that  whofe  component  parts  of  feltfpar,  fcliorl,  or  quartz,  were  fo 
fmall  as  to  refenible  pretty  compact  compound  lavas,  or  fome  of  our  mixed  whin-flones  in 
Scotland.  All  thefe  varieties  would  be  found  at  no  great  diftance  from  each  other.  I 
brought  fome  fpecimens  from  Tiger's  Berg,  a  hill  about  500  feet  perpendicular  height, 
which  have  every  appearance  of  having  undergone  the  action  of  fire.  They  refemble  half 
vitrified  fcoriae,  and  would  be  taicen  for  them,  but  that  they  were  a£lually  broken  off  from 
the  granite,  and  difcover  all  its  parts  in  the  fradture.  The  fummit  of  this  hill  is  irregular, 
with  fcveral  pits  and  holes  among  the  rocks.  A  little  higher  than  it,  and  I  fuppofe  nearly 
about  200  miles  from  the  fea,  you  meet  what  are  called  the  falls.  They  are  only  five  or  fix 
rapids  within  the  fpace  of  a  mile  or  two,  formed  by  ledges  of  very  clofe-grained  gray  granite 
that  run  acrofs  the  river.  There  are  breaks  in  each  of  them,  through  which  the  dextrous 
Indians  are  able  in  their  light  canoes  to  pafs  up  at  any  feafon,  even  the  driefl: ;  and  when  the 
.  river  is  fwelled  by  the  rains  they  become  totally  obliterated.  Two  days  journey  or  two  and 
a  half  above  this  is  the  great  fall,  where  the  ftream  comes  over  the  face  of  a  rock,  as  we  are 
informed,  twenty  feet  high. 

.  Savannahs. — Savannahs,  ever  fince  the  difcovery  of  America,  have  been  known  to  oc- 
cupy large  fpaces  in  the  fouthern  parts  of  that  continent.  They  are  to  be  met  with 
abundantly  in  Guiana,  and  are  of  two  kinds  very  dillinfl;  from  each  other,  the  luct  and  the 
dry.  Of  the  former  many  are  extenfive  as  the  eye  can  reach — immenfe  verdant  plains  occupy- 
ing the  whole  face  of  a  country,  with  or  without  a  few  ftraggling  infulated  patches  of  wood. 
In  the  dry  feafon  they  appear  meadows  of  long  grafs  or  reeds,  and  are  feldom  prafticable 
for  any  diftance,  for  the  bottom  is  very  rarely  dry.  In  the  wet  feafon  they  are  all  one  entire 
plain  of  water,  over  the  furface  of  which  the  grafs  ftill  rifes,  but  which  may  be  every  where 
navigated  in  the  courialls  or  canoes.  Towards  the  end  of  the  drought  the  Indians  fet  fire 
to  them.  The  young  growth  which  fucceeds  attracts  the  deer  ;  and  the  native,  on  the  re- 
turn of  the  half  deucalion  days,  purfues  them  in  his  little  bark  acrofs  their  former  plains. 
The  foil  upon  thefe  favannahs  can  neither  be  very  deep  nor  very  good;  yet  water  may  be 
always  commanded,  and  labour  and  induftry  might  convert  thefe  deferts  into  rice  fields. 
It  is  a  queftion  whether  the  days  of  flavery  will  ever  fee  that  event.  The  culture  of  this 
ufeful  vegetable,  which  in  the  eaft  has  for  ages  been  the  ftanding  food  for  millions,  brings 
too  moderate  a  return,  at  leaft  in  an  infant  colony,  for  the  rapacious  agricultural  fyftem  of 
the  Weft  Indies. 

The  dry  favannahs  are  neither  fo  frequent  nor  fo  extenfive,  yet  we  have  paffed  through 
fome  of  them  feveral  leagues  in  circumference.  They  are  formed  along  the  flats  on  the 
top  of  the  fand  ridges,  and  covered  by  a  very  thin  coat  of  verdure.  They  refemble  exactly 
enough  fome  of  the  bare  moors  in  Scotland.  Many  beautiful  plants  of  the  clafs  gynandria 
are  their  chief  ornaments,  as  is  alfo  the  orchis,  which  grows  in  fimilar  fituations  with  you. 
Some  melaftomas  and  more  rhexias  fupply  the  place,  and  bear  fomewhat  of  the  habit  of 
the  ericje;  for  your  fedums  and  faxifrages  is  the  little  fauvagefia;  and,  in  hollows  of  the  ' 

R  r  2  fame 


|04  0"  *^^  Airtrkan  Sugar  Maf  It, 

fame  favftnnalis  wlicre  mo'ifture  prevails,  what  I  never  could  have  expe^ed  to'fee  wJthm 
five  degrees  of  thf  line,  and  not -more  than  50  or  100  feet  above  the  level  of  the  fea,  th« 
drofera  lifts  its  humble  head  from  a,  hed  of  the  fphagnum  paluftre. 

[_To  le  coiitinued.l 


s, 


V. 

On  the  Sugar  Maple.    By  Citizen  TesSIER  *. 


'UG  AR  is  one  of  the  aiofl  common  produ£ls  of  the  vegetable  kingdom,  and  is  found 
ready  formed  in  a  great  number  of  fpecies.  It  is  'obtained  from  the  wild  cherry-tree, 
(merifier),  the  poplar,  the  birch,  the  nut-tree,  the  pods  of  gleditzia,  maize,  the  afclepias 
fyriac?.,  &c. ;  but  the  tree  which  next  to  the  fugar-cane  affords  this  produdl  in  the  greateft 
abundance  and  heft  quality  is  the  fu gar  maple  (acer  faccharinam). 

Many  fpecies  of  maple  grow  naturally  in  France,  Germany,  Switzerland,  and  England. 
The  acer  opalus  is  found  particularly  in  Italy,  and  that  which  Linn.eus  diftinguidies  by 
the  name  of  acer  tataricum  in  Afia.  But  America  is  the  country  of  mod  of  the  fugar 
maples.  It  was  from  Quebec  that  Mr.  Sarafm  forwarded  this  tree  to  the  Jardin  des  Plantes. 
Father  Charlevoix,  at  the  diftance  of  a  league  and  a  half  from  Quebec,  was  regaled,  to  ufe 
his  own  exprefTion,  with  the  faccharine  juice  of  maple.  Kalm,  at  the  pod  of  Tliree  Rivers, 
between  Montreal  and  Quebec,  faw  the  procefs  of  making  fugar  with  the  fap  of  the  maple. 
The  acer  faecharinum  is  there  fo  common  that  it  is  ufed  for  fuel. 

A  climate  in  which  the  winters  are  long  and  fevere  is  bed:  adapted  to  the  fugar  maple. 
I  do  not  know  whether  it  is  found  in  a  more  northerly  latitude  than  that  of  Canada.  In 
that  country,  though  fituated  in  the  latitude  of  about  44°,  the  cold  lafts  longer,  and  is  more 
intenfe  than  in  France,  on  account  of  the  enormous  mafles  of  water,  the  woods  and  the 
mountains.  Towards  the  fouth,  the  maple  becomes  very  rare,  fo  that  few  are  feen  beyond 
the  lower  part  of  Louifiana.  Kalm  has  remarked,  that  they  grow  to  a  lefs  height  in  the 
fouthern  parta  of  the  United  States  than  in  Canada,  and  that  they  do  not  grow  in  New 
Jerfey  and  Pennfylvania,  except  on  the  fides  of  the  Blue  Mountains,  and  the  fteep  banks  of 
livers  expofed  to  the  north.  And  even  in  this  expofhion  they  io  not  obtain  more  than 
one  third  or  a'  quarter  of  the  height  they  acquire  in  Canada.  The  intelligent  Dupratz', 
author  of  the  Hiftory  of  Louifiana,  confirms  what  Kalm  has  advanced.  The  fpecies  o£ 
maple  which  we  poffefs  in  France  do  not  thrive  excepting  in  places  where  the  cold  is  of 
long  duration.  Kalm  aflures  us,  that  being  in  the  neighbourhood  of  Chefter,  a  fmall  town 
on  the  Delaware  in  Pennfylvania,  he  faw  red  maples  on  a  marfhy  foil  accompanied  by  the 
alder— an  obfervation  which  points  out  the  foil  in  which  this  tree  ought  to  be  planted.  The 
Aigar  maple  is  alfo  found  in  the  State  of  Vermont  in  Kenrucky,  in  the  country  beyond  the 
Ohio,  oppofite  to  Pennfylvania  and  Virginia.  According  to  the  author  of  the  Amcricaw 
Geography,  fugar  is  made  from  it  in  thefe  countries  ;  but  it  does  not  feem  to  be  an  obje6t' 
«f  great  intereft,  as  the  author  of  that  geography  fimply  mentions  the  fad". 

•  Inferred  in  the  Arnales  d'Agriculture,  and  thence  c^i^  into  La.  Decade  Philofophique,  &c.  Noj  9^^ 
•tm  f  L  from  which  lad,  wprk  the  preferu  trawflation  is  made, 

6  Citizen 


On  the  jfmermn  Sugar  Mtipk.  305 

Ch'iXen  Michau,  nurfcryman  at  Charles  Town,  has  a  confiderable  quantity  near  the 
banks  of  the  Ohio  in  the  ftate  of  Virginia,  beyond  the  Apalachian  mountains.  They 
were  planted  in  a  good  foil.  In  this  country  the  maples  have  fuch  a  growth,  that,  if  the 
author  of  the  American  Geography  may  be  credited,  fycamores  are  to  be  met  with  forty- 
four /ect  in  circumference  *. 

The  Canadians  have  long  been  accuftomed  to  ufe  the  juice  of  the  maple  as  a  refrefliing 
beverage.  When  it  ifTues  out  of  the  tree  it  is  clear,  whitifli,  and  of  a  cool  faccharine  tafte. 
By  expofure  to  the  fun  in  fummeJr,  it  is  converted  into  good  vinegar.  It  is  obtained  by 
boring  the  trunk  of  the  tree,  .taking  care  to  dire£l  tlie  inftrument  upwards.  The  blade  of 
a  knife,  or  a  piece  of  thin  wood  in  the  form  of  a  ruler,  is  inferted  to  conduft  the  fluid  to 
a  veflcl  placed  beneath  for  its  reception :  without  this  precaution,  it  would  flow  down  the 
bark  of  the  tree  and  be  loft.  A'lr.  Gaultier  obferves,  that  the  perforation  muft  be  made 
into  the  proper  ligneous  circles,  and  that  the  faccharine  juice  is  flot  to  be  obtained  by  making 
incifions  in  the  middle  bark  or  the  liber,  or  at  leaft  that  the  quantity  obtained  will  be  very 
fmall.  At  the  commencement  of  the  thaws  the  fap  flows  abundantly  for  about  three 
weeks;  after  which  it  thickens  and  entirely  flops.  The  maples  afibrd  more  fap  the  greater 
the  quantity  of  fnow  has  been,  and  the  more  rigorous  the  winter.  The  moft  favourable 
period  is  when  the  fnow  begins  to  melt,  and  the  cold  weather  ftill  continues.  The  flow  is 
confiderable  in  the  fprlng,  when  the  thaws  are  great  and  decided.  The  colder  the  nightsi 
die  greater  the  quantity  of  fap  which  flows  on  the  following  day.  It  feldom  flows  during 
the  night,  unlefs  the  weather  be  mild.  If  thefe  obfervations  had  been  made  in  all  parts 
where  there  are  fugar  maples,  they  would  afford  reafon  to  conclude,  that  the  regular  alter- 
nation of  great  cold  during  the  night  and  very  perceptible  heat  during  the  day-time,  which 
takes  place  in  the  northern  parts  of  America,  contributes  to  elaborate  the  fap  of  the  maple 
and  render  it  fweet. 

The  juice  of  the  maple  is  colle£l:ed  earlier  or  later  according  to  the  country.  In  the 
vicinity  of  Quebec,  Three  Rivers,  and  Montreal,  it  lafts  from  the  middle  of  March  to- 
the  middle  of  May,  when  the  fun  begins  to  have  power ;  but  near  Lake  Champlain  it  is 
collected  from  the  middle  of  February  to  the  early  part  of  March.  In  this  country  the 
thaws  commence  about  the  end  of  January. 

If  we  give  credit  to  Mr.  Gaultier,  the  French  taught  the  favages  to  extradl  fugar  froni 
the  fap  of  the  maple ;  but  if  we  depend  on  Kalm,  the  favages  knew  this  art  before  the 
Europeans  had  difcovered  America,  and  the  latter  people  have  only  followed  the  pradlice 
-  of  the  favages.  Whatever  may  be  the  value  of  thefe  two  unfupported  afl^ertions,  it  is 
certain,  that  in  order  to  extraft  this  fugar  the  liquor  is  boiled  over  the  fire,  taking  care  to 
ftir  and  flcim  it  until  it  has  obtained' a- very  thick  confiftence.  If  it  be  kept  too  long  over 
the  fire,  it  acquires  a  tafte  of  honey  like  melafles.  This  fugar  becomes  fpontaneoufly  pu- 
rified. It  is  fometimes  clarified  with  whites  of  eggs  before  it  is  fufiicientiy  boiled,  and  after 
the  clarification' the  ebullition  is  continued  :  when  the  boiling  is  fufEcietit,  the  fugar  is 
poured  into  a  vefleh  which  gives  it  its  form.     In  Canada^   wherever  the  maples   abound^ 

•  This  appears  to  me  tO'be  greatly  exaggerated;  the  largeft  American  fycamores,  according  to  the  report  of 
perfons  who  have  raeafujreditheni,  being, no  more  than-from  twenty  to  twemy.-fout  feet  round.     JVc/s  of  the 

they 


3o6  On  the  Jmerican  Sugar\MapIt, 

they  make  this  fugar,  as,  In  France,  cherry  brandy  is  made  In  fuch  places  as  abound  with 

cherries. 

The  firft  juice  which  is  extracted  from  the  maples  In  the  fpring  is  fweeter  than  that 
which  flows  at  the  end  of  the  feafon,  when  it  has  the  tafte  which  in  Canada  is  called  the 
tafte  of  the  fap.  This  lafl,  from  which  the  fugar  is  more  difficultly  extra£led,,  is  kept  in 
the  ftate  of  fyrup.  It  contains  more  fugar  in  proportion  as  the  weather  is  colder.  Trees 
of  the  fame,  age  do  not  afford  the  fame  quantity  either  of  fap  or  of  fugar,  neither  do  the 
quantities  of  fugar  in  like  quantities  of  fap  agree.  That  of  the  old  maples,  which  is  lefs 
abundant,  is  more  faccharine.  The  fap  of  maples  which  grow  in  a  mountainous  and  ftony 
foil  is  more  faccharine  than  that  of  fuch  trees  as  grow  in  low  humid  foils.  This  obferva- 
tion  holds  good  with  regard  to  all  vegetable  produdlions. 

A  tree  of  three  or  four  feet  in  circumference  may  afford  from  thirty  to  fixty  pints  of 
liquor,  and  foroetimes  more;  and  a  pound  of  fugar  is  about  the  quantity  obtained  from  fix- 
teen  pints,  that  is  to  fay,  nearly  three  pounds  of  fugar  per  tree.  Care  muft  be  taken  to 
make  the  openings  on  the  fame  fide  every  year,  in  order  that  the  tree  may  not  die.  The 
fouth  or  fouth-wcft  is  the  proper  fide.  Mr.  Gaultier  obtained  in  a  quarter  of  an  hour  a 
pint  of  this  faccharine  fluid  from  a  perforation  three  inches  deep,  made  on  this  fide  of  a 
tree  four  feet  in  circumference  ;  at  the  fame  time  that  a  perforation  in  the  fame  tree  on 
the  north  and  north-eaft  afforded  him  only  a  chopine  or  half  pint  in  the  fame  time.  If 
the  perforations  be  multiplied  the  tree  becomes  exhaufted,  and  its  old  age  is  accelerated.  It 
feems  to  me  that  It  would  be  advifable  to  leave  the  tree  untouched  every  fecond  year,  in 
the  fame  manner  as  good  economllls  fuffer  their  mulberry  trees  to  repofe  at  like  periods. 

Father  Charlevoix  caufed  a  refiner  at  Orleans  to  make  a  trial  to  refine  the  maple  fugar. 
He  found  feme  difl^icuities  in  the  attempt ;  but  with  attention  thefe  difficulties  have  been 
furmounted,  for  it  Is  at  prefent  refined  in  America.  This  fugar,  in  the  ftate  we  ufually  re- 
ceive it  from  that  country,  may  be  kept  a  long  time  without  alteration,  as  I  have  feen  in  a 
piece  in  the  colleftion  of  Citizen  Juffieu. 

Gaultier  and  Kalm  affirm,  that  the  maple  fugar  of  the  favagcs  of  Canada  Is  mixed  with 
flour,  whether  to  rciuder  It  more  nutritious  or  to  augment  the  quantity;  but  this  kind  of 
fophiftication,  if  the  maple  fugar  fliould  become  an  obje£i:  of  commercial  intereft,  would 
be  eafily  difcovered.     Such  fugar  is  whiter  than  other  famples  not  fo  adulterated. 

The  fugar  of  the  maple  Is  employed  by  the  inhabitants  of  the  remote  parts  of  Canada, 
for  the  fame  ufes  as  the  fugar  of  the  cane  with  us,  becaufe  they  are  poor ;  and  this  fugar, 
though  lefs  pleafing  to  the  fight  and  tafte,  cofts  them  nothing  but  the  trouble  of  tapping 
the  trees  and  evaporating  the  fluid.  This  fugar  is  more  difficultly  foluble  in  water  ;  and  its 
fweetening  quality.  If  I  may  ufc  this  expreffion  after  Kalm,  is  to  that  of  the  fugar-cane 
as  one  to  two.  The  richer  inhabitants  of  towns  which  by  commerce  have  Intercourfe  with 
the  colonies  where  the  fugar-cane  Is  cultivated,  prefer  for  their  ordinary  confumption  the 
fugar  of  this  laft  plant,  and  ufe  that  of  the  maple  as  an  agreeable  medicament.  It  is 
particularly  recommended  for  coughs  and  colds,  and  its  ufe  is  even  prefcrlbed  for  diforders 
of  the  lungs. 

It  is  eftimated  that  between  twelve  and  fifteen  thoufand  pounds  weight  of  maple  fugar 
18  annually  made  In  Canada.  It  is  the  product  of  four  or  five  thoufand  trees.  From  this 
izStf  fuppofing  an  arpent  of  land  of  a  hundred  perches,  at  eighteen  feet  the  perch,  planted 

7  with 


On  the  American  Sugar  Maple,  '  3c  7 

with  maples  in  full  growth,  each  affording  fixty  pints  of  liquor,  the  produ£l  would  be  fix 
hundred  and  fixty-fix  pounds  of  unrefined  fugar.  For  the  arpent  may  fupport  two  hundred 
and  twenty-two  trees,   placing  the  flems  at  twelve  feet  diftance  from  each  other. 

I'he  maples  begin  to  afford  a  certain  quantity  of  fugar  at  the  age  of  18  years,  and  ceafe 
to  afford  any  at  bz>  or  70  years.  In  America,  thofe  trees  are  reckoned  large  which  rife 
above  60  feet.  I  here  are  fome  which  are  tw6  feet  in  diameter.  The  wood  of  certain 
fpecies  is  hard,  and  of  a  clofe  texture,  if  they  be  tapped  too  foon,  there  is  reafon  to  fear 
that  it  may  injure  the  growth,  and  render  the  produdt  of  fugar  inconfulerable.  It  is  there- 
fore of  advantage  to  determine  the  period  of  life  at  which  the  tapping  ought  to  be  com- 
menced.  And  on  this  head  it  has  been  afcertained,  that  the  bed  and  moll  abundant  pro- 
duce is  obtained  from  trees  of  the  middle  fize,  and  that  fcarcely  any  is  afforded  by  maples 
which  are  large  and  old. 

The  fugar  maple  has  not  hitherto  been  cultivated  in  France,  but  as  an  objefl  of  cu- 
riofity.  Some  enlightened  cultivators,  who  endeavour  to  dire£l  all  their  purfuitsto  objedls 
of  utility,  have  entertained  the  hope  that  fome  advantage  might  be  derived  from  this  tree. 
There  are  a  fufncient  number  of  thefe  trees  at  prefent  in  France,  to  afford  the  means  of 
determining  whether  they  produce  fugar  in  our  climate,  and  in  what  quantity ;  and  this 
decifion  is  neceffary  to  be  had  before  the  cultivation  in  the  large  way  ought  to  be  propofed. 
For  it  is  poffible  that  they  may  afford  a  very  faccharine  liquid  in  America,  and  much  lef* 
in  Europe,  as  happens  with  the  liquid  amber;  which,  according  to  Kalm,  affords  mucb 
balfam  in  New  Mexico  and  South  Carolina;  but  produce  lefs  in  Virginia,  and  none  at  all 
in  Penfylvania  and  New  York. 

The  difference  which  exifts  between  the  cold  of  the  nights  in  the  American  countries 
and  thofe  of  Europe  under  the  fame  degrees  of  latitude,  the  heat  of  the  fun  being  equal, 
mud  neceffarily  influence  the  progrefs  of  vegetation. 

In  the  mean  time,  until  we  (hall  acquire  the  neceffary  information,  if  it  Ihould  be  thought 
fit  to  increafe  the  number  of  thefe  trees,  the  following  is  the  method  of  proceeding :  —  The 
fureft  and  moft  ufeful  is  to  fet  the  feeds.  They  may  be  found  in  the  plantations  of 
M.  Duhamel,  M.  LesMalelherbes,  and  feveral  other  curious  gardeners.  It  is  obferved,  that 
the  acer  faccharinum  brought  from  America  is  not  raifed  but  with  difficulty,  either  becaufe 
it  is  not  tranfplanted  at  the  proper  time,  or  becaufe  it  has  failed  of  receiving  proper 
care  during  the  paffage.  ft  would  perhaps  be  neceffary  to  fend  exprefsly  to  America  an 
intelligent  gardener,  or  to  give  inftruftions  in  the  country  to  an  attentive  perfon  to  fend 
the  bell  feed  to  France,  and  even  the  plant,  in  order  to  accelerate  our  progrefs  T'hc- 
acer  faccharinum  never  grows  from  flips ;  but  it  grafts  very  well  on  the  fycamore.  Its 
refemblance  to  the  plane  maple  of  Europe,  which  is  fuch  that  the  two  trees  are  con- 
founded, feem«  to  (hew  th*t  it  would  be,mofl  convenient  to  graft  upon  this  tree;  but  a- 
gardener  has  feveral  times  attempted  this  m  vain.  An  opaque  matter  which  lies  between 
the  wood  and  the  bark  oppofes  the  union.  The  maple  negundo,  the  only  one  which  is 
multiplied  by  flips,  is  likewife  propagated  by  feed  and  by  layers.  The  jafper- maple  is 
grafted  with  the  greateft  fuccefs  on  the  fycamore.  It  rifes  with  a  better  ftem  v.'hen  grafted 
in  this  manner ;  but  care  mull  be  taken  to  graft  very  low.  Ripe  feeds  of  the  red  maple- 
have  not  jet  been  obtained  j  but  it  may  be  raifed  from  American  feed,  and  in  this  manner 

the 


jog  On  the  Afnerican  Sugar  Maple. 

the  two  indivic'.uals  may  be  obtained.     The  accr  tomentofum,  laftly,  Is  one  of  tliofe  wluch 
IS  moft  eafily  multiplied  in  our  climates. 

Though  it  is  laid  that  fome  fpecies  of  maple  may  grow  in  light  ftoney  foils,  they  profper 
better  in  good  ground.  The  foil  of  the  mountains  cannot  always  be  conGdered  as  bad. 
The  red  maple  delights  in  the  plains  and  valleys,  and  all  the  fpecies  are  injured  by  a  flrong 
fun.  They  fucceed  well  if  flieltered  to  the  fouth  by  mountains  or  woods,  as  I  conclude 
from  the  flate  of  tlie  fugar  maples  of  Maleflierbes  and  Rambouillet. 

The  advantages  which  would  refult  from  cultivating  the  fugar  maples  in  Europe,  and 
particularly  in  FrancCj  are  relative  to  the  quantity  of  fugar  they  may  all'ord.  When 
it  fliall  be  proved  that  a  great  quantity,  or  at  lead  feveral  pounds  per  tree,  can  be  obtained, 
lands  which  are  even  fufceptible  of  cultivation  will  be  devoted  to  this  obje£l.  Some  fpecies 
will  require  to  be  placed  on  the  flopes  of  mountains,  where  the  fnow  and  cold  weather 
pr^;vail  for  a  long  time.  Others  will  be  planted  in  low  fituations  on  the  borders  of  mea- 
dow lands,  lakes,  rivers,  and  grounds  approaching  to  marfli  lands,  fuch  as  thofe  where  the 
»JJer  delights  to  grow.  Such  plantations,  which  may  contribute  to  ii:creafe  the  produc- 
tion of  fugar  .without  a;ny  other  care  than  that  of  tapping  the  trees  and  concentrating  the 
liquor,  will  be  of  great  utility  in  fupplying  our  habitual  want  of  this  article.  Befides 
\yhich,  the  fugar  maple  prefents  to  turners,  mufical  inftrument  makers,  inlayers,  the  work- 
ers in  ftaining  wood,  and  gunfmiths,  a  valuable  material,  which  in  fome  of  the  fpecies  is 
reined  and  marbled.     It  is  proper,  therefore,  to  encourage  the  growth  of  this  tree. 


In  addition  to  the  fa£ls  and  obfervations  contained  in  the  foregoing  memoir,  which,  if 
conclufive  with  rcfpefi;  to  France,  would  probably  be  much  more  fo  with  regard  to  the 
northern  diftrifts  of  our  illand  ;  it  may  be  added,  that  Dr.  Benjamin  Rufll  of  Philadelphia 
communicated  an  excellent  paper  on  the  fame  fubjeft  to  the  American  Philofophical  So- 
ciety, which  was  publiflied  in  their  Tranfaftions,  vol.  iii.  in  the  year  i  793.  The  abfl;ra<3: 
of  his  paper  is  as  follows  : 

The  acer  faccharinum  of  Linne,  or  fugar  maple  tree,  grows  in  great  quantities  in  the 
weflern  countries  of  all  the  middle  ftates  of  the  American  Union.  It  is  as  tall  as  the  oak, 
and  from  two  to  three  feet  in  diameter;  puts  forth  a  white  bloflbm  in  the  fpring  before 
any  appearance  of  leaves  :  its  fmall  branches  afford  fuftenance  for  cattle,  and  its  aflies 
afford  a  large  quantity  of  excellent  pot-afli.  Twenty  years  are  required  for  it  to  attain 
its  full  growth.  Tapping  does  not  injure  it ;  but,  on  the  contrary,  it  affords  more  fyrup, 
and  of  a  better  quality,  the  oftener  it  is  tapped.  A  fingle  tree  has  not  only  furvivetl,  but 
flourifhed  after  tapping  for  forty  years.  Five  or  fix  pounds  of  fugar  are  ufually  afforded 
by  the  fap  of  one  tree— though  there  are  inftances  of  the  quantity  exceeding  twenty 
pounds.  The  fugar  is  feparated  from  the  fap  either  by  freezing,  by  fpontaneous  evapora- 
tion, or  by  boiling.  The  Ijtter  method  is  the  mod  ufed.  Dr.  Ruih  defcribes  the  procefo, 
\vhlch  is  fimple,  and  praclifed  without  any  difficulty  by  the  farmers. 

From  frequent  trials  of  this  fugar,  it  does  not  appear  to  be  in  any  refpeiE^  inferior  to 
that  of  the  Weft  Indies.  It  is  prepared  at  a  time  of  the  year  when  neifher  infed  nor 
the  pollen  of  plants  exifts  to  vitjst?  it,  as  is  tb§  cafe  with  common  fugar.  Frooj  calcula- 
tions 


M.ipU  Strgar.'-^ChemUal  affJ  Mechamcol  InvefiiUfi,  JOj 

tlons  grounded  on  exifting  fads,  it  is  afcertained  fhat  America  is  now  capable  of  pro^ 
ducing  a  furplus  of  one  eighth  more  than  its  own  corifumption  i  that  is,  on  the  whole, 
about  135,000,000  pounds,  which  in  the  country  may  be  valued  at  15  pounds  weight  for 
6ne  dollar.  Dr.  Rufli  mentions  many  other  benefits  his  country  may  derive  from  this  in» 
valuable  tree,  and  concludes  his  paper  with  an  account  of  fome  of  the  advantages  of  fugar 
to  mankind ;  not  merely,  as  commonly  confidered  to  be  a  luxury,  but  as  an  excellent 
wholefome  and  nourifliing  article  of  food.  Annexed  alfo  is  an  extrafl  from  the  report  of 
the  committee  of  the  Britifli  privy  council  on  the  fubjedl  of  the  African  flave  trade> 
Containing  Mr.  Botham's  ftatement  of  the  mode  of  cultivating  a  fugar  plantation  at 
Batavia*. 


VI. 

T'/je  Progre/i  of  Mechanical  Di/covery,  exemplified  in  an  Account  of  a  Machine  for  cutting 

Files.     iW.M.\) 

X  HE  folly  and  confequcnt  diftrefs  of  purfuiiig  experiments  In  chemiflry,  for  the  fok 
{jurpofe  of  commercial  advantage,  has  been  repeatedly  obferved  both  by  public  Writers  and 
in  private  life.  The  obfcurity  which  attends  the  procefles  of  this  art,  the  imperfe£lion« 
of  theory,  and  the  feduftions  of  hope,  have  united  to  lead  men  in  purfuit  of  medicines  of 
uncommon  powers,  and  agents  which  fliould  convert  the  cheaper  ftietals  into  gold  and' 
filver.  It  is  a  fubje£]t  of  no  wonder,  to  thofe  who  have  not  fufFered  their  mental 
habits  to  be  vitiated  by  thefe  fedudive  analogies,  that  difficulties  and  difappointment 
fliould  attend  the  life  of  a  man  thus  employed.  But  mechanics  have,  in  general,  been 
more  favourably  regarded.  A  number  of  fimple  and  admirably  ufeful  efFeds  are  produced 
by  the  operation  of  machines.  We  daily  fee  improvements  produced  by  means  eafily 
underftood.  The  mechanic  who  endeavours  to  ftrikc  into  a  new  path,  finds  he  can 
reafon  from  what  has  been  done  before  him,  and  ufually  begins  his  work  with  a  convic- 
tion that  the  refults  he  is  dcfirous  of  obtaining  will  infallibly  happen.  Hence  it  is  that 
a  prodigious  number  of  new  fchemes  find  their  way  into  books;  on  which  both  the  author 
and  the  reader  fet  a  high  value,  and  of  which  the  futi'Uy  is  difcerned  only  by  a  few  prac- 
tical men.  Some  of  my  readers  have  fuppofed  this  fource  of  information  to  be  much 
more  produftlve  than  it  really  is.  A  very  flight  enquiry  concerning  new  machines  and 
,inventioi?8,  whether  they  have  been  carried  into  efFed,  and  whether  they  have  fuperfeded 
the  old  methods  of  operation,  will  immediately  ftrike  out  of  the  lifl;  of  valuable  articles 
not  lefs  than  nine  tenths  of  the  objeds  to  which  the  public  attention  is  folicited.  And 
if  it  be  aflerted  that  the  defcription  of  fuch  abortive  projeds  might  be  of  ufe  to  afford 
hints  to  fpeculators,  I  muft  take  the  liberty  to  obferve,  that  it  is  a  mofl  ferious  thing  to 
engage  in  a  new  invention,  and  a  no  lefs  ferious  duty  in  the  editor  of  a  public  work  to 

*  To  avoid  the  impHtation  of  plagiarifm,  I  muft  take  notice  tliat  the  two  laft  paragraphs  appeared  in  an 
anonymous  publication  in  the  year  1794,  but  were  written  by  myfclf.     N. 

f  As  the  obfervation  on  the  wrapper,  thai  all  fafers  tvitboni  r.ame  or  fi^nature  are'tvritten  by  the  Editor,  has 
been  overlooked  by  fome  readers,  who  have  made  enquiry  refpefling  the  authors  bf  fuch  papers,  he  ha*  thought 
it  expedient  in  future  to  add  his  initials.  ' 

Vol.  II.— Oct.  1798.  Sf  ^  j«r 


3?0  ^f'f  Prcgrefs  ef  Mechanical  Invention. -^Machine  f«r  cutllng  FilfJ^ 

be  well  afTured  of  the  value  of  what  he  recommends  or  fufFers  to  recommend  itfcff  to  his 
readers.  From  views  of  this  kind,  it  has  appeared  to  me,  that  1  fliould  do  fome  fervice  to 
«n  a£t:ive  fet  of  men,  foiiie  of  whom  have  efFeclually  farved  this  country,  if  I  were  con- 
cifcly  to  point  out  the  courfc  of  mechanical  invention,  in  order  that  thofe  individuals  only 
may  be  induced  to  engage  in  it,  who  poflefs  the  acquifitions  and  means  to  do  it  with  fomc 
effect. 

We  will  therefore  fuppofe  a  very  acute  theorift,  who  Is  not  himfclf  a  workman,  nor  in 
the  habit  of  fuperintending  the  pra£lical  execution  of  machinery,  to  have  conceived  the 
notion  of  fomc'  new  combination  of  the  mechanical  powers  to  produce  a  determinate 
clTedl  -,  and  for  the  fake  of  perfpicuity,  let  us  take  the  example  of  a  machine  to  cut  files*. 
His  firft  conception  will  be  very  fimple  or  abftra£l;ed.  He  knows  that  the  notches  in  a 
file  are  cut  with  a  chizel  driven  by  the  blow  of  a  hammer,  by  a  man  whofe  hands  are 
employed  in  applying  thefe  inftruments,  while  his  foot  is  exerted  in  holding  the  file  on  an 
anvil  by  means  of  a  (trap.  Hence  he  concludes,  that  it  muft  be  a  very  eafy  operation  60 
fix  the  chizel  in  a  machine,  and  caufe  it  to  rife  and  fall  by  a  lever,  while  a  tilting  hammer 
of  the  proper  fize  and  figure  gives  the  blow.  But,  as  his  attention  becomes  fixed,  other 
demands  arife,  and  the  fubjeft  expands  before  him.  The  file  muft  be  fupported  upon  a 
bed  or  mafs  of  iron,  of  wood,  of  lead,  or  other  material : — it  muft  be  fixed  either  by 
fcrews  or  wedges,  or  weights,  or  fome  other  efFedual  and  ready  contrivance  : — and  the 
file  itfelf,  or  elfe  the  chizel,  with  its  apparatus  for  ftriking,  muft  be  moved  through  equal 
determinate  fpaces  during  the  interval  between  ftroke  and  ftroke,  which  may  be  done 
either  by  a  ratchet  wheel  or  other  efcapement,  or  by  a  fcrew.  He  muft  examine  all  thefe 
objefts,  and  his  ftock  of  means  in  detail;  fix  upon  fuch  methods  as  he  conceives  to  ha 
moft  deferving  of  preference  ;  combine,  organize,  and  arrange  the  whole  in  his  mind ; 
for  which  purpofe  folitude,  daiknefs,  and  no  fmall  degree  of  mental  effort,  will  be  re- 
quired : — and  when  this  procefs  is  confiderably  advanced,  he  muft  have  recourfe  to  his 
drawing  board.  Meafured  plans  and  fe£lions  will  then  fhew  many  things  which  his 
Imagination  before  difregarded.  New  arrangements  to  be  made,  and  unforefeen  difB- 
culties  to  be  overcome,  will  infallibly  prefent  themfelves.  The  firft  conception,  or  what 
the  world  calls  the  invention,  required  an  infinitely  fmall  portion  of  the  ability  he  muft 
now  exert.  We  will  fuppofe,  however,  that  he  has  completed  his  drawings.  Still  he 
poffeffes  the  form  of  a  machine  only ;  but  whether  it  fliall  anfwer  his  purpofe,  depends  on 
his  knowledge  of  his  materials.  Stone,  wood,  brafs,  lead,  iron  forged  or  caft,  and  ftecl 
in  all  its  various  modifications,  are  before  him  ;  the  general  proceffes  of  the  workfliop  by 
which  firmnefs,  truth,  and  accuracy,  are  alone  to  be  obtained  ;  and  thofe  methods  of 
treatment,  chemical  as  well  as  mechanical,  which  the  feveral  articles  demand  : — thefe  and 
numberlefs  other  pradlical  obje£ls  call  for  that  (kill  and  attention,  which  may  either 
lead  to  fuccefs,  or,  by  their  deficiency,  expofe  him  to  the  Ignorance  or  obftlnacy  of  his 
workmen.    If  he  fliould  find  his  powers  deficient  under  a  profped  fo  arduous— if  tc 

*  Tranfaftions  of  the  American  Philof.  Society,  vol.  ii.  or  Repertory,  v.  184.  The  file  is  fixed  on  a  bed 
•f  lead,  and  a  chizel  fixed  at  the  end  of  a  lever,  is  ftruck  down  with  a  hammer.  This  lever  rifes  again  of  itfelf 
ky  means  of  a  fpring,  and  during  its  rife  it  moves  a  ratchet  wheel,  conneftid  with  the  fupportof  the  bed;  whi(b 
confe^uently  it  ibifts  together  with  the  file  after  every  llroke. 

3  »nn6t 


Mechanical  Invention.'— Dutch  Proce/s  .for  making  Turnfol  blue.  311 

cannot  fubmit  to  the  fevere  difcipline  of  feeing  his  plans  reverfed,  and  his  hopes  repeatedly 
deferred — if  unfuccefsful  experiment  fhould  produce  anguifli  without  affording  inflruc- 
tion,  what  will  then  remain  for  him  to  do  ? — Will  he  embitter  his  life  by  directing  his 
inceflant  efforts,  his  powers  and  refources,  to  a  fafcinating  objeft,  in  which  his  diflicul- 
ties  daily  increafe  j  or,  will  he  make  that  ftrong  exertion  of  candour  and  fortitude,  which 
will  lead  him  to  abandon  it  at  once? 

Thefe  are  the  inevitable  (lages  of  operation,  through  which  every  inventor  in  mechanics 
muft  pafs.  To  the  mere  habit  of  viewing  objefts  in  new  lights,  the  habit  which  leads  ttJ 
the  outline  of  invention,  he  mull  add  the  power  of  difpoling  his  notions  in  the  form  of 
an  individual  engine  or  inflrument ;  and  he  mufl  himfelf  become  a  workman,  capable  of 
difcerning  the  means  by  which  his  ideas  may  become  realized  in  the  proper  materials.  It 
may  perhaps  feem  as  if  I  had  felefted  an  inflance  of  difficulty,  and  indulged  my  imagina- 
tion in  a  fketch  of  obflacles  feldom  likely  to  be  met  with.  This,  however,  is  far  from 
being  the  cafe.  Nothing  feems  more  fimple  and  eafy  at  firfl  fight,  than  to  make  an 
engine  to  cut  notches  in  a  piece  of  fteel ;  and  a  very  ingenious  perfon,  in  the  work  above 
referred  to,  has  accordingly  given  an  accurate  defign  of  an  engine  for  that  purpofe,  which 
no  doubt  he  thinks  mufl  fucceed.  But  manufafturers  well  know  the  value  of  fuch  an 
engine,  and  have  long  ago  attempted  to  make  it  by  that  3S\A  various  other  methods  without 
fuccefs.  That  engine  in  particular,  promifmg  as  it  appears,  is  utterly  incapable  of  work- 
ing, for  feveral  reafons,  fcarcely  to  be  difcovered  but  by  practical  men,  but  which  cannot 
with  fufficient  brevity  be  here  detailed.  And  with  regard  to  general  obflacles  in  the  detail 
of  inventions,  I  am  fo  far  from  magnifying  them,  that  I  am  warranted  by  much  ex- 
perience, as  well  on  my  own  behalf,  as  that  of  others  whofe  plans  and  operations  have 
come  before  me,  to  affirm,  that  no  mechanical  invention  really  new  was  ever  brought  to 
its  cpmplete  or  perfe£l  ftate,  at  fo  fmall  a  charge  as  three  times  the  coft  of  the  finifhed 
engine,  cxclufive  of  the  incalculable  labour  of  the  contriver. 


VII. 

The  Dutch  Procefs  for  making   the  Blue  dijiinguijhed  by  the  Name  of  Turnfol  *. 

i"  ^  ICHEN,  Archil,  or  in  cafe  this  lad  caanot  be  obtained,  the  greater  mofs  of  the  oak, 
is  dried,  cleaned,  and  pulverized  in  a  mill,  refembling  the  oil  mill,  and  then  lifted  through 
a  brafs  wire  fieve,  the  interftices  of  which  do  not  exceed  one  millimetre  in  width  (i -250th 
of  an  inch).  The  fitted  powder  is  then  thrown  into  a  trough,  and  mixed  with  an  alkali 
called  vedas,  which  is  nothing  elfe  but  the  cendres  gravelees  in  powder.  The  proportioij 
is  one  part  by  weight  0/  the  alkali,  to  two  parts  of  the  pulverized  vegetable.  This  mix* 
tare  Is  moiflened  with  a  fmall  quantity  of  human  urine  ;  the  urine  of  other  animals 
does  not  contain  a  fufficient  quantity  of  ammoniac.  The  mixture  ferments,  and  is  kept 
molll  by  fucceffive  additions  of  urine.  As  foon  as  the  materials  have  become  red,  they 
are  transferred  into  another  trough,  where  they  are  again  moiflened  with  urine,  and  ftirred 
■to  renew  the  fermentation.  Some  days  afterwards  the  pafle  acqulrcis  a  blue  colour,  iq 
which  ftate  it  is  carefully  mixed  with  one  third  of  excellent  pot-afh  well  powdered ;  and 

*  Sfom  the  Journal  du  Commerce,  copied  in  the  Decade ^'hilof,  &c.  No.  57. 

Sf  2  with 


312  L'ttmui.—J^cwicnhn  Doflriue  of  Trart/m'JpiU  tind  RefeB'toiu 

with  this  new  mixture  certain  trays  are  filletf,  which  are  one  metre  (39^  inches)  deep,  and 
eight  decimetres  {314^  inche>)  wide.  When  the  fermentatioa  which  takes  place  for  the 
third  time  has  given  the  parte  a  confiderably  deep  blue  colour,  chnlk  or  powdered  marble 
i«  added,  and  the  whole  is  well  and  perfeftly  mixed.  TIils  laft  addition  is  made,  not  to  im- 
prove the  quality  of  the  blue,  but  to  add  weight.  It  is  merely  an  affair  of  profit.  The  blue 
thus  prepared  is  put  into  iron  moulds  32  centimetres  long  and  22  fquare  at  the  end 
(i|  inch  by  x-^  of  an  inch).  The  moulded  pieces  are  then  placed  upon  deal  planks,  in  welU 
aJred  lofts,  to  dry  ;  at*ter  which  they  are  packed  in  cafks  for  fale. 

The  Hollanders  made  a  fecret  of  this  procefs:  and  in  order  to  miflead,  they  have  publifh- 
ed,  that  the  blue  was  made  with  rags  coloured  by  the  plant  turnfol ;  whence  it  has  obtained 
its  denomination  *.     We  may  derive  much  profit  by  carrying  this  difcovery  into  praclice. 


VIII. 

Experiment!  and  Remarij  on  certain  Ranges  of  Colours  hitJierto  unohferved,  ivhich  are  productd 
by  the  relative  Pofition  of  plain  Glajfes  -with  regard  to  each  ether.  {W,  N.) 


T. 


HOSE  ranges  of  colours  which  are  afForded  by  the  refleflion  and  tranfmiffion  of  light 
through  thin  tranfparent  plates,  have  been  an  obje£t  of  much  attention  to  philofophers,  evet 
Cnce  the  experiments  made  by  Robert  Hooke  and  Sir  Ifaac  Newton.  The  latter  of  thefe 
philofophers  endeavoured  to  generalife  the  fads  by  a  ilatement,  which,  becaufe  in  part  hy- 
pothetical, has  been  treated  with  contempt  by  fomc  eminent  men,  though  it  has  been  re- 
ferred to  in  moft  difquifitions  on  thefe  phenomena.  When  a  convex  lens  is  applied  to  a 
plain  glafs,  it  is  well  known  that  coloured  circles  furround  the  place  of  contaft  j  and  as 
thefe  circles  are  found  to  vary  in  their  dimenfions,  the  nearer  the  glafles  lie  with  refped  to 
each  other,  whether  by  means  of  the  curvature  or  of  preffure,  it  has  been  concluded  thafr 
tlie  effeds  are  caufed  or  governed  by  the  diftances  of  the  furfaces.  From  various  confidera- 
tions  Sir  Ifaac  was  led  to  conclude,  that  the  rays  of  light  are  themfelves  poffefled  of  a  pro- 
perty, by  which,  in  certain  equidiftant  points  of  their  length,  they  are  difpofed  to  entCF 
tranfparent  bodies,  and  in  certain  other  points,  intermediate  between  thefe,  they  are  dif- 
p6fed  to  be  refleded.  From  this  aflumption  he  deduced,  that  if  a  ray  of  light  pafled 
through  the  firft  furface  of  a  medium,  it  would  be  either  tranfmitted  or  teflcfled  at  the 
fecond  furface,  accordingly  as  the  diftance  might  happen  to  coincide  with  a  point  of  tranf- 
miffion or  refle£lion.  According  to-  this  doftrine,  it  muft  follow  that  the  interval  will 
govern  the  effect,  not  in  confequence  of  its  own  magnitude,  but  of  the  precife  number  of 
»neafures,  or,  as  he  calls  them,  fits  of  tranfmiffion  or  refledion  it  may  contain. 

Thus,  for  example,  if  we  fuppofe  a  ray  of  indefinite  length  to  be  divided  into  equal  parts,, 
and  imagine  certain  marks  of  divifion  to  fubfift  ;  if  the  ray  pafs,  through  the  firft  furface  of  a 
medium  exadly  at  one  of  thefe  marks,  it  will  be  tranfmitted  through  any  furface,  however 
diftant,  which  (hall  be  remote  from  the  firft,  either  nearly  or  accurately  fome  precife  num- 
ber of  parts ;  beeaufe  the  fits  of  tranfmiffion  are  refpedively  at  thofe  points  or  marks :.  and 

•Englilh  writers  have  ufed  this  denomination.    But  the  dry-falters,  «  dealers  in  drugs,  diftingui/h  thefe 


M&ih  by  the  name  of  litmus. 


Vticewmon  C*hUrt  preJuftd  in  flat  Phtes  of  Glafs,  3  rj 

en  the  other  hand,  it  will  be  refle(fted  Trotn  any  furface  whofe  diftance  is  meafured  by  fome 
f  number  of  whole  parts,  together  with  half  a  part ;  becaufc  the  fits  of  refleftion  lie  half-way 
between  the  divifions.  In  this  ftatement  I  have  merely  enunciated  what  are  fuppofed  to  be 
the  fails,  aird  have  not  attended  to  his  fuppofition  of  an  etherial  elaftic  fluid,  pervading 
«11  fpace  and  thrown  into  undulations  more  rapid  than  the  velocity  of  light  itfelf.  Neither 
can  I  at  prefent  enter  into  any  dlfcuffion  concernit/g  its  probable  value.  My  prefent  obj/idV 
is  to  relate  a  few  experiments,  which,  at  the  fame  time  that  they  (hew  the  exiftence  of 
thefe  fits  at  very  confiderable  intervals,  appear  to  prove  that  the  refle(!^ion  and  tranfmifiioii 
of  light  in  the  fame  medium  is  governed  by  other  circumflances  as  well  as  by  the  diftance 
between  the  confines  or  furfaces.  Thefe  experiments  lead  to  many  fpeculations  and  ex- 
tended paths  of  enquiry.  It  has  long  been  my  intention  to  multiply  and  repeat  them,  in 
order  to  difcover  the  laws  upon  which  they  depend :  but  other  avocations  have  already  de-^ 
layed  the  accomplilhment  of  this  purpofe  for  more  than  feven  years  ;  for  which  reafon,  I 
hope  that  my  defire  to  fee  the  objed  purfued  by  others  may  operate  as  an  apology  for  the 
imperfe£l  ftate  of  the  refearch,  of  which  I  here  prefent  the  commencemen^ 

The  experiments  of  the  Abbe  Mazeas  on  colours  produced  by  applying  flat  plates  of  glafs 
to  each  other,  are  related  at  full  length  in  Prieftley's  Hiftory  of  Light  and  Colours,  p.  499. 
This  philofopher  found,  that  rubbing  the  glafles  together  caufed  the  colours  to  appear  at  the 
fame  time  that  adhefion  took  place  between  them,  and  Mufchenbroeck  found  thatlenfes  of 
long  focus  do  not  afford  colours  after  having  been,  laid  by  for  a  length  of  time  unlefs  they 
be  wafhed  and  wiped.  One  of  the  moft  remarkable  circumftances  in  the  experiments  of 
Mazeas  was,  that  the  colours  of  his  flat  plates  are  moveable  by  a  very  flight  increafe  of 
temperature;  which  produces  an  efte£l  fimilar  to  what  would  have  arifen  from  removing 
the  glafles  further  afunder,  or  diminifliing  the  preflure  which  might  have  been  applied  to 
them.  Beccaria  was,  I  believe,  the  firft  who  obferved  that  thefe  colours  may  be  produced 
by  fuperinducing  an  eledric  charge  on  the  external  furfaces  of  two  plates,  which  are  by 
this  means  made  to  adhere.  But  in  all  the  obfervations  I  have  met  with,  whether  made  by 
Prieftley  in  his  Hiftory,  or  by  any  other  writer,  thefe  powers  have  been  fuppofed  to  operate 
by  increafing  or  diminifliing  the  diftance  between  the  furfaces.  The  following  fadts  will 
fliew  that  this  conclufion  requires  to  be  modified. 

In  the  year  179 1  I  cut  a  plate  of  very  clear  glafs  into  portions,  which  were  intended  to- 
be  ufed  to  defend  a  veflel  of  quickfilver  from  the  agitation  of  the  air.     Its  colour,  whea- 
viewed  edgewife,  was  a  very  light  green,  and  it  had  been  carefully  ground  by  an  optician^ 
■with  its  fides  truly  parallel  to  each  other.     The  thicknefs  was  twelve  hundredths  of  aa 
inch.     A  piece  3,2  inches  long  and  2,4  \ii'ide  was  laid  upon  another  larger  piece,  both 
having  been  previoufly  wiped.     The  refult  was,  that  faint  colours  appeared  in  rows  about 
fix  or  feven  in  number.     Preflure  appeared  to  alter  thefe  very  little  in  pofition  5  but  it  pro- 
duced other  more  vivid  colours,  which  were  much  more  moveable,  and  crofled  the  former 
without  afFe£ling  them.    The  fcarcely  moveable  ranges  were  very  little  diftuxbed  by  the  heat 
of  the  finger  applied  againft  the  undermoft  glafs;  though  this  application  was  fuSicient  to 
produce  a  very  great  alteration  in  the  figure  of  the  other  ranges^     When  the  upper  glafs. 
was  lightly  placed  upon  the  lower,  the  faint  and  fcarcely  moveable  ranges  appeared  alone,, 
and  the  glafles  had  very  little  adhefion  ;  fo  that  the  uppermoft  Aided  about  on  the  larger 
jilate  beneath,  without  feeming  to  carry  the  ranges  with  it,  but  arrived  at  other  ranges^ 

whichi 


3^4  iJew  Phenomena  of  the  Tranftriijfton  and  ReJleB'ton  of  Light, 

\Fhich  from  their  immobility  feemed  as  if  attached  to  the  lower  glafs.  Thefc  fcarcely 
moveable  colours,  however,  were  quickly  moved;  and  brought  nearer  to  each  other  by  raifing 
one  edge  of  the  glafs  with  the  hand  ;  and  they  continued  vifible  when  the  glafs  was  lifted 
as  high  as  one-fortieth  or  thirtieth  of  an  inch,  by  flipping  a  knife  under  its  edge.  When 
I  plate  of  metal  was  placed  beneath  the  lower  glafs,  and  eleftricity  (which  from  the  difpofi- 
tion  of  the  machine  happened  at  that  time  to  be  negative)  was  communicated  to  the  upper 
plate,  the  vivid  colours  appeared,  and  the  adhefion  of  the  glafles  was  increafed ;  but  the 
fcarcely  moveable  ranges  remained  little  if  at  all  afFe£ted.  When  the  glafles  were  taken  from 
the  machine  towards  the  window,  the  vivid  colours  flowly  receded  as  the  eleilricity  was 
difperfed,  and  in  this  ftate  they  were  very  advantageoufly  and  evidently  feen  crofling  the 
ether  lefs  moveable  ranges. 

Thefe  fads  appeared  at  that  time  to  lead  to  no  other  conclufion  than  that  the  moveable 
ranges  had  been  difturbed  by  fome  other  circumftance  befides  that  of  the  mere  diftancc  of 
the  plates :  for,  if  the  diftance  had  indeed  been  varied,  it  feems  reafonable  to  fuppofe  that 
both  fets  of  ranges  would  have  been  affe£ted. 

Soon  afterwards,  upon  making  fome  obfervations  with  the  artificial  horizon,  and  a 
fextant  conftruded  by  Troughton,  I  obferved  a  feriesof  colours  in  the  horizon-,glaf3,  when 
the  pofition  of  zero  was  to  be  afcertained.  They  appeared  both  in  the  filvered  and  the 
clear  part.  The  pofition  of  the  glafles,  when  the  colours  were  feen,  was  very  nearly 
parallel  as  to  the  vertical  fituation  of  the  planes  ;  but  it  admitted  of  the  index  being  moved 
through  nearly  forty  minutes  before  they  difappeared.  Thefe  glafles,  namely  the  index-" 
glafs,  and  the  horizon-glafs,  were  3!  inches  afunder. 

This  laft  fa£b  appears  to  juftify  the  inference  of  Newton,  who  confidered  the  colours  of 
thick  and  thin  plates  as  depending  on  the  fame  caufe  ;  which  dodrine  was  applied  by  Dr. 
Pemberton,  to  account  for  the  numerous  ranges  of  colours  fometimcs  obferved  beneath  the 


common  rainbow  *. 


As  one  of  the  greateft  difliculties  in  Newton's  dodrine  feems  to  have  been  that  the  fits 
of  refledion  and  tranfmiflion  are  fuppofed  to  extend  to  vaft  diftances,  it  feemed  defirable  to 
repeat  this  experiment  with  as  great  an  interval  between  the  glafles  as  could  conveniently  be 
had.  With  this  view  I  placed  one  plate  of  glafs  on  the  furfacc  of  a  veflel  of  mercury,  and 
held  anotTier  in  my  hand  parallel  to  it,  in  fuch  a  pofition  that  the  refleded  light  from  the 
firfl:  pafled  through  the  fecond  glafs  to  my  eye.  The  white  clouded  fky  and  the  chimney 
of  an  oppofite  houfe  were  feen  by  refledion  in  both  glafles,  and  it  was  eafy  to  move  the 
Mpper  glafs  till  both  images  of  the  chimney  coincided.  In  this  pofition  the  glafles  would 
have  been  parallel  if  the  objed  had  been  indefinitely  dift;ant ;  but  in  the  prefent  cafe,  the 
parallelifm  could  not  be  obtained  but  by  a  flight  elevation  of  the  moveable  image.  By  this 
difpofition  the  colours  were  made  to  appear  when  the  plates  were  four  feet  afunder,  and  I 
have  no  doubt  but  that  the  fame  would  have  happened  at  much  greater  diftances  if  the  im- 
perfed  method  of  adjufting  the  parallelifm  could  have  been  applied. 

The  fame  eff*ed,  as  might  naturally  be  expeded,  took  place  when  the  eye  was  fo  placed 
as  to  receive  the  refleded  light  from  the  lower  glafs,  after  it  had  been  tranfmitted  through  th« 
vpper. 

♦  Philof.  Tranf.  abridged,  vol.  vii.  or  Prieflley's  Optics,  p.  j9«,  , 

In 


■  Gauntry  and  CUmatf  near  the  American  Laktt^  315 

"  *!«»  addition  to  thefc  obfervations,  it  maybe  remarked,  that  1  have-not  obferved  thefs 
colouri  ill  fuch  plates  of  common  looking-glafs  as  I  have  tried  ;  that  they  do  not  appear  in 
a  fmall  pocket  fcxtant  which  I  poflefs;  that  the  difpofition  to  exhibit  thefe  colours  fcems  to 
be  iacicafed  by  wiping  or  fiidUon,  and  alfo,  as  I  think,  by  a  continuance  of  the  acSlion  which 
is  ncceflUry  to  produce  them,  or  caufe  them  to  run  along  the  furface  of  the  glaflcs. 


IX. 

Some  Account  of  the  Count n  and  Climate  of  the  North-ivejlem  Lakes  of  America.     By  Majof- 
C,  Sh'AN,  Faymii/Ier  to  the  Wefern  Army  *. 

D'Etroit,  oa.  10,  1797. 
«  *  *  *  *  *  *'**  *  *  *  4 

*  *  *  *  *  *  *       •'•'*-'^^'^  *-         *  *  ^.         ^ 

"  This  country  is  yet  new,  and  almoft  in  a  ftate  of  nature,  like  Its  inhabitants.  It  is  true 
the  foil  is  extremely  rich  and  fertile  ;  and  it  is  to  a  fuperabundant burden, of  vegetation, 
and  a  flat  furface  for  hundreds  of  miles  together  producing  much  ftagnant  water,  that  we 
may  attribute  the  unwholfomenefs  of  the  climate,  which  is  almoil  certain  to  afFe£l  the  in- 
habitants with  bilious  complaints  every  fall  f . 
************ 

«  *  •  *  *  *  *,  *  *  *  *  * 

"  Gen.  Wilkinfon  arrived  here  in  June  this  year,  and,  after  making  fome  prompt  arrange- 
ments for  the  garrifon,  propofed  a  voyage  to  Michilimackinac,  and  invited  me  to  accompany 
him ;  and  on  the  4th  day  of  Auguft  we  embarked  in  a  floop  of  about  70  tons  burthen. 
We  had  a  fafe  and  pleafant  trip,  not  only  to  Michilimackinac,  but  even  Into  Lake  Superior  v 
and  returned  to  this  place  on  the  4th  of  laft  month,  highly  gratified  indeed. 

«*  We  firft  left  this  place,  and  traverfed  Lake  Sinclair,  a  handfome  circular  lake  about 
twenty-five  miles  acrofs.  We  then  proceeded  up  the  river  of  that  name,  which  is  broad 
and  very  handfome,  for  about  forty  miles,  to  a  rapid  at  the  entrance  of  Lake.  Huron ; 
traverfed  this  immenfe  beautiful  lake,  three  hundred  miles  long  ;  and  arrived  on. the  i5th.of 
Auguft  at  the  ftreight  which  unites  it  to  Lake  Michigan.  This  ftreight  is  broad  j  and  the 
Ifle  de  Bois  Blanc,  or  White  Wood  Ifland,  Round  Ifland,  and  Michilimackinac  Ifland  form . 
a  clufter  in  the  middle  of  the  ftreight,  and  afford  a  romantic  and  majeflic  landfcape  from]the 
fea.  The  Ifle  de  Bois  Blanc  is  eleven  miles  and  a  half  long,  and  from  two  to  three  wide,, 
lying  parallel  to  the  two  coafts of  the  ftreight,  but  neareft  to  the  fouth-fide.     Round  Ifland: 

*  From  the  Medical  Rcpofitory,  printed  at  New  York,  vol.  i.  p.  526.  It  is  introduced  by  the  following 
Note  of  the  American  Editor  ; 

Note.  The  following  Article  confifts  of  Extra£ts  from  a  Letter  of  Major  Swan  to  Capt.  Frye,  command- 
ant of  the  garrifon  at  Governor's  Ifiand,  who  was  fo  obliging  as  to  communicate  them  to  one  of  the  Editsrs  ; 
and  they  are  now  made  public  with  the  confent  of  the  Author.  Thefe  Extradts  are  briefly  made  from  a 
Journal  kept  by  Major  Swan  at  the  time  ;  and  are  ioferted  for  the  threefold  purpofe  of  illuftrating  the  table  of 
thermometrical  obfervations  which  follow,  of  commutiicating  a  fliort  but  authentic  view  of  a  part  of  the  north-  - 
weftern  territory,  and  of  inviting  further  information. 

+  Thefe  remarks  have  particular  reference  to  the  neighbourhood  of  D'Etroit, 


31 6  Countff  ani  Climate  near  tin  Jmencan  Laiei. 

it  about  tlirce  miles  in  circumference,  and  lies  at  the  upper  or  fonth-wcft  end  of  Dc  Bols 
Blanc.  The  ifland  of  Michilimackinac  is  circular,  and  lies  between  the  upper  end  of  Dc 
Bois  Blanc  and  the  north- weftern  coaft  of  the  ftreight;  having  a  chanhel  of  about  one  mile 
and  a  half  between  it  and  De  Bois  Blanc,  and  a  channel  of  nine  miles  between  it  and  the 
north-weftern  coaft  of  the  ftreight.  It  meafures  feven  miles  and  tliree  quarters  in  circum- 
ference, and  is  nearly  circular.  On  the  fouth-fide  of  this  ifland  there  is  a  fmall  bafon  of  a 
fegment  of  a  circle,  ferving  as  an  excellent  harbour  for  veflcls  of  any  burthen,  and  for  canoes. 
Around  this  bafon  the  village  is  built,  having  two  ftireets  of  nearly  a  quarter  of  a  mile  in 
length,  a  Roman  chapel,  and  containing  eighty-nlhe  houfes  and  ftores  ;  fomc  of  them 
fpacious  and  handfome,  with  white  lime  plaftering  in  front,  which  fliews  to  great  advan- 
tage from  the  fea.  At  one  end,  and  in  the  rear  of  the  town,  is  an  elegant  government- houfc 
of  immenfc  fize,  and  finiftied  in  great  tafte.  It  is  in  the  form  of  |1^  |1  ;  one  ftory  high,  the 
rooms  fifteen  feet  and  a  half  in  the  clear.  It  has  a  fpacious  garden  in  front,  laid  out  with  tafte, 
and  extending  from  the  houfe  on  a  gentle  declivity  to  the  water's  edge.  There  are  two  na- 
tural limpid  fprings  in  the  rear  of  the  houfe,  and  a  very  lively  grove  of  fugar-trees  called  the 

'  Park.  Suitable  out-houfes,  fl;ablcs  and  offices  are  added  ;  and  it  is  enriched  on  three  fides 
with  beautiful  diflant  profpefls.  Twenty  rods  from  the  rear  there  is  a  fudden  and  almolt 
perpendicular  afcent  of  about  a  hundred  feet  of  rock,  upon  the  top  of  which  ftands  the  fort, 
built  of  ftone  and  lime,  with  towers,  baftions,  &c.  occupied  by  our  troops,  and  command- 
ed by  Major  Burbeck.  About  half  a  mile  from  the  fort,  in  the  rear,  there  is  an  eminence 
which  I  eftimate  to  be  about  two  hundred  and  fifty  feet  from  the  furface  of  the  water.  This 
fpot  commands  an  extenfive  and  fublime  view  of  the  adjacent  country.  The  fort,  the  vil- 
lage, the  neighbouring  iflands  and  channels  feem  proftrated  at  your  feet ;  while  to  the 
fouth-weft;  you  look  into  the  immenfity  of  Lake  Michigan,  which  lofes  itfelf  in  the 
fouthern  hemifphere  ;  and  to  the  north-weft  the  great  Lake  Huron  lies  expanded  to  the 
bounds  of  the  horizon.     It  was  a  beautiful  morning  when  I  had  this  view. 

"  This  celebrated  ftreight  is  the  only  key  to  the  immenfe  lucrative  fkin  trade  now  folelj 
carried  on  by  Britifli  fubjeds  from  Montreal,  with  the  nations  of  Indians,  called  th« 
Sauteurs  or  Chipewas,  Sioux,  Reynards,  &c.  who  inhabit  the  water-courfes  that  fall  into 
the  Mifliffippi  between  the  Illinois  and  the  falls  of  St.  Anthony.  Canoes  are  loaded  and 
fitted  out  by  thefe  traders  every  year  from  Michilimackinac.  They  commonly  fet  out  in 
July,  and  return  in  June,  July  or  Auguft  the  year  following,  to  Michilimackinac,  from 
whence  they  ftarted.  Here  they  are  again  met  by  the  Montreal  canoes  with  frefh  goods, 
exchange  loading,  and  each  return  from  whence  they  came.  The  Montreal  canoes  pene- 
trate to  Michilimackinac  by  way  of  Grand  River ;  which,  with  the  exception  of  a  fmall 
portage,  conveys  them  to  the  northern  point  of  Lake  Huron ;  and  return  by  the  fame  route. 
Thofc  from  Michilimackinac  penetrate  the  interior  or  Indian  country  by  way  of  Green 
Bay,  an  arm  of  Lake  Michigan,  thence  through  Fox  River  into  the  Miffiflippi  and  its* 
tributary  ftreams  j  and  return  alfo  to  Michilimackinac  by  the  fame  route. 

**  On  the  22d  of  Auguft  we  left  Michilimackinac,  and  on  the  23d  anchored  in  the 
"ftreight  of  St.  Jofeph,  which  leads  to  Lake  Superior.  At  this  place  nature  has  dilplayed 
▼ery  handfomely  again.  The  mouth  of  the  ftreight  is  about  thirty  miles  wide,  but  fo 
ftrewcd  over  with  innumerable  fmall  circular  Iflands  that  it  is  difficult  to  obtain  a  view  in 

.  any  dire^ion  of  more  than  fix  or  eight  miles.     Indians  have  forqetimes  been  ioft  among 
9  theft 


Coantty  a»d  Clhtiate  near  the  Amcr'icsn  Lakes,  31^ 

tliefe  Iflands  for  weeks  together.  They  extend  into  Lake  Hnron,  and  continue  along  the 
north-weft  coaft  of  the  lake  for  an  hundred  and  eighty  miles,  and  are  called  by  the  favages 
the  Meneto  or  Devil's  iflands.  From  the  entrance  of  the  ftreight  at  a  place  called  the 
Detour,  it  is  nine  miles  to  the  new  Britidi  garrifon  built  on  the  point  of  the  ifland  of  St. 
Jofeph,  commonly  called  the  Carraboo  ifland.  This  is  the  largeft  in  the  ftreight  5  being 
iLOont  twenty-five  miles  long,  and  from  ten  to  three  broad. 

"  On  the  13d  of  Auguft  we  left  tlie  veflel,  embarked  in  three  canoes,  afcended  the 
drcight  in  what  is  called  the  Canoe  channel,  and  encamped  at  Mufkito  Point. 

"  The  24th,  at  one  o'clock  P.  M.  we  arrived  at  the  falls  of  St.  Marie,  called  le  Saut  de 
St.  Marie.  Thefe  falls  are  about  three-quarters  of  a  mile  long  and  half  a  mile  wide  ;  the 
rapid  not  violent;  and  the  perpendicular  of  the  whole  fall  about  thirty  feet.  There  is  a  fmall 
kind  of  village  on  the  United  States  fide  containing  fundry  large  warehoufes,  and  a  few 
decent  dwelling-houfes  occupied  by  the  Agents  of  the  Canada  North-weft  Trading  Com- 
pany.   There  is  not  a  clear  white  woman  in  the  place. 

*  •  »  *  «  The   25th  it  rained         *  *  *  *  # 

*■  •■  *  **  On  the  26th  we  fet  off  In  two  bark  canoes  from  the  upper  end 

■^  the  portage  for  Lake  Superior.  *  •  *.  At  one  o'clock  P.  M.  we  entered 
Lake  Superior  ;  looked  fairly  into  it ;  drank  of  its  waters;  ate  our  dinner  ;  and  put  about 
with  a  fine  fair  wind.  We  reached  the  falls  a^ain  at  four  o'clock  in  the  afternoon  ;  placed 
experienced  guides  with  ftrong  paddles  in  the  bow  and  ftern  of  each  canoe;  hoifted  the 
fifteen  ftripes ;  and  launched  into  the  bofom  of  the  cataraft.  In  a  moment  we  were  fafe 
*jn  the  bafon  at  the  bottom  of  the  falls  ! 

"  We  embarked  early  on  the  27th.  Having  a  ftrong  current  and  fair  wind  we  defcend- 
•ed  in  the  fhip  channel,  and  reached  the  vefTel  at  Carraboo  ifland,  at  nine  o'clock  in  the 
evening. 

"  The  28th  we  put  to  fea  again ;  and  on  the  4th  of  September  at  fun-down  reached 
this  placci 

"  I  inclofe  to  you  herewith  degrees  of  heat  which  were  afcertained  by  regular  obferva- 
tion  with  Fahrenheit's  thermometer  every  day ;  by  which  you  will  perceive  that  the  tempe- 
rature of  the  Lakes  differs  widely  from  that  of  the  Atlantic  country." 


On  comparing  the  Table  of  Obfervations  which  is  annexed  with  obfervatlons  made  ohj 
the  fame  days  in  this  city,  the  difl^erence  will  appear  fo  remarkable  that  the  reader  may  fuf- 
peft  fome  error  in  the  inftrtiment  made  ufe  of  by  Major  Swan  :  and  fuch  were  my  fufpi« 
cions.  But  croflSng  the  Eaft  river  to  Governor's  Ifland  in  company  with  that  gentleman 
on  the  4th  of  March  1798,  he  obferved,  that  the  wind  which  we  then  felt,  and  which  was 
very  briflc,  rcfembled,  in  point  of  temperature,  that  which  he  experienced  on  Lake  Huroij 
on  the  14th  and  15th  of  Auguft  1797  ;  and  added,  that  on  the  fame  evening  a  froft  affefte^ 
the  gardens  at  Michilimackinac  fo  feverely  as  to  deftroy  the  greater  part  of  the  vegetable?. 


Vol.  11.— Oct.  1798.  Tt  TABLE 


Zil^. 


Climate  near  the  American  Laiis. 


TABLE 


OF    THE 


Degrees  of  Heat  obfervcd  on  Fahrenlieit's  Thermometer,  from  Augufl:,4^ 

to  September  4,   1797. 


1797. 


Auguft  4 

5 
6 

7 
8 

9 
10 

II 

12 

J3 

14 

15 

16 

17 
18 

^    19 

20 

21 

22 

*3 

24 
25 

26 

•27- 
28 
29 
30 

Ji 
I 

2 

3 

A 


5ept. 


6  o'clock 

A.M. 

u  o'clock 
M. 

70'ciock 

P.M. 

Average 

66 

63  i 

59 

62i- 

59 

66 

63. 

62- 

55i 

6? 

66 

62 

60 

67 

67 

64 

59 

61 

61 

60 

57 

62. 

52 

57 

58. 

62 

6j 

60 

63 

•  591: 

6b  - 

60 

57 

60 

61 

59 

55 

5  si 

5.5 

55 

50 

49 

47 

48 

45 

bb 

54 

55 

52 

70 

53 

58 

54 

69 

60 

6i 

52 

67 

62 

60 

54 

64 

56 

58 

53 

64 

58 

58 

62 

63 

^3 

62 

54 

61 

59 

58 

57 

65 

6oi 

62 

50 

63 

6oi 

57 

46 

53 

49 

49 

46 

49 

50 

48 

50 

56 

49 

51 

40 

50 

46 

45 

51 

54 

5» 

54 

49 

57 

53 

53 

50 

56 

49 

51 

48 

57. 

47 

50 

5' 

59 

50 

53 

49 

5« 

50 

52 

48 

56 

49 

51 

RtmarkSj    where. 


Lake  Sinclair. 

Ditto. 

RFver  Sinclair. 

Ditto, 

Ditto. 

Ditto. 

Ditto. 

Lake  Huron. 

Ditto. 

Ditto. 

Ditto. 

Michilimackinac. 

Ditto. 

Ditto. 

Ditto. 

Ditto. 

Ditto^ 

Ditto. 

Streights  of  St.  Jofeph.. 

Ditto. ' 

Ditto. 

1-  alls  of  St.  Marie. 

Lake  Superior. 

Streights  of  St.  JofepIt^_ 

Lake  Huron. 

Ditto. 

Ditto. 

Ditto. 

Ditto. 

Dito. 

River  Sinclaisi. 

Lake  Sinclair. 


sX.'>f/t'. 


Telegraphs  of  thi  French  an^  of  Robert  'lionh.     *  4f* 


^n  EJay  on  the^rt  of  conveying 'Secret  and  Sivift  Intelligence,      By  RlCHAKJi  -LorELt. 
'      '''EvGEWORTiiyEfq.F.R.S.andM.R.I.J.*. 


M, 


.ODELS  of  the  French  T'elegraph  have  been  fo  often  exhibited,  and  the  machine 
iifelf  is  To  well  known,  that  it  is  not  neceiTary  to  defcribe  it  minutely  in  this  place.  Ic  is 
fufEcient  to  fay,  that  it  Gonfifts  of  a  tall  pole,  with  three  moveable  arms,  winch  may  be 
fceri  at  a  confiderable  diilance  through  telefcopes  ;  chefe  arms  may  be  fet  in  as  many  dif- 
ferent pofitions  as  are  requifite,  to  exprefs  all  the  letters  of  the  alphabet : — By  a  fuccefhve 
combination  of  letters  ihewn  in  this  manner,  words  and  fentences  are  formed,  and  intel- 
ligence communicated.  No  doubt  can  be  made  of  the  utility  of  this  machine,  as  it  has 
been  applied  to  the  mod  important  purpofes.  It  is  obvioufly  liable  to  miftakes,  from  the 
number  of  changes  requifite  for  each  word,  and  from  the  velocity  with  which  it  muft  be 
moved  to  convey  intelligence  with  any  tolerable  expedition. 

The  name,  however,  which  is  -well  chofen,  has  become  fo  familiar,  that  I  fliall  with  a 
flight  alteration  adopt  it  for  the  apparatus  which  I  am  going  to  defcribe.  Telegraph  is  a 
proper  name  for  a  machine,  wliich  dcfcribes  at  a  diflance.  Telelograph,  or  contrafledly 
Tellogrdph,  is  a  proper  name  for  a  machine  that  defcribes  -words  at  a  diilance. 

Dr.  Hooke,  to  whom  every  mechanic  philofopher  muft  recur,  has  written  an  eflay  upon 
the  fubjedt  of  conveying  fwift  intelligence,  in  which  he  propofes  to  ufe  large  wooden 
letters  in  fucceffion.  The  fiege  of  Vienna  turned  his  attention  to  the  bufinefs.  This 
method  is  more  cumbrous  than  the  French  Telegraph,  but  far  lefs  liable  to  error. 

I  tried  it  before  I  had  feen  Hooke's  work  in  the  year  1 767,  in  London  ;  and  I  could 
diftinftly  read  letters  illuminated  with  lamps  in  Hampflead  church-yard,  from  the  houfe 
of  Mr.  Elers  in  Great  Ruflel  Street,  Bloomfbury,  to  whom  I  refer  for  the  date  and  cir- 
cumftance. — ^To  him  and  to  Mr.  E.  Dclaval,  F.R.S.  to  Mr.  Perrot  of  Harehatch,  and  to 
Mr.  Woulfe  the  chemift,  I  refer  for  the  precedency  which  I  claim  in  this  invention.  In 
that  year  I  invented  the  idea  oF  my  prefent  tellograph,  propofing  to  make  ufe  of  windmill 
fails,  inftead  of  the  hands  or  pointers  which  I  now  employ.  Mr.  Perrot  was  fo  good  as 
to  accompany  me  more  than  once  to  a  hill  near  his  houfe,  to  obferve  with  a  telefcope  a 
windmill  ait  Nettlebed  }  which  places  are,  I  think,  fixteen  miles  afunder.  My  intention  at 
that  time  was,  to  contrive  not  only  a  fwift  but  an  unfufpedled  mode  of  intelligence  :  By 

■•  Tranfaftions  of  the  R.  Irifli  Academy,  vi.  125.  The  firft  part  of  this  pap«r  confifts  of  near  thirty  pages 
of  very  iaierefting  hiftorical  detail,  refpeftin^  the  art  of  conveying  inrclliiicncc  by  founds  and  llgnaU.  Jt  was 
praftifed  by  Thefeus,  in  the  Argonautic  expedition  ;  by  Agarnemnon,  at  the  fuge  of  Troy  ;  arnl  by  Mardonius, 
in  the  time  of  Xerxes.  It  is  frequently  mentioned  in  Thucydides;  it  was  ufed  by  Tamerlane;  by  the  Moors 
in  Spain ;  and  by  the  Welch  in  Britain  ;  by  the  Irifli ;  and  by  the  Chinefc,  on  their  famous  wall  of  fifteen 
hundred  miles,  by  which  they  fcparatcd  themfelvcs  from  Tarcary.  I  have  omitted  litis  part  on  account  of  its 
length.  • 

T  t  2  means 


320  0»  fie  Art  ef  ceiweying  Secret  and  S-wlft  Tnielllgtrtee, 

means  of  common  windmills  this  might  have  been  cffefted,  before  an  accountof  the 
French  Telegraph  was  made  public  *. 

My  machinery  confifts  of  four  triangular  pointers  or  hands,  each  of  which  points  like  ' 
the  hands  of  a  clock  to  different  fituations,  in  the  circles  which  they  defcribe. 

It  Is  eafy  to  diftinguilh  whether  a  hand  moving  vertically,  points  perpendicularly  down- 
wards or  upwards,  horizontally  to  the  right  or  left,  or  to  any  of  the  four  intermediate 
fituations. 

The  eye  can  eafily  perceive  the  eight  different  pofitions  in  which  one  of  the  pointers  is 
reprefented,  plate  xiii.  fig.  i.  by  turning  the  eye  to  the  circle  A. 

A  fimilar  circle  may  be  imagined  round  each  of  the  pointers,  by  which  the  numbers 
which  they  are  intended  to  exprefs,   may  be  difcovered  with  much  facility. 

Of  thefe  eight  pofitions,  feven  only  are  emj)]oyed  to  denote  figures ;  the  upright  pofition 
of  the  hand  or  pointer  being  referved  to  reprefent  O  or  Zero.  The  figures  thus  denoted,, 
refer  to  a  vocabulary  in  which  all  the  words  are  numbered.  Of  the  four  pointers,  plate  1. 
that  which  appears  to  the  left  hand  of  the  obferver,  reprefents  thoufands,  the  others  hun- 
dreds, tens  and  units  in  fucceffion,  as  in  common  numeration. 

t  In  the  annexed  plate  the  four  large  pointers  (land  at  2774,  which  in  the  common  ar^ 
rangement  of  my  vocabulary,  denotes  the  Royal  Irifh  Academy.  For  permanent  ftations, 
which  may  be  feen  clearly  with  tolerable  glaffes  at  twenty  miles  dillance,  ftone  or  wooden 
pillars  fixteen  or  twenty  feet  high  mud  be  folidly  erefted  :  on  the  top  of  thefe  a  move- 
able circle,  or  platform,  turns  horizontally  upon  a  centre:  on  this  platform  an  axis  moves- 
vertically,  and  carries  the  arm  or  pointer  along  with  it.     Eight  handles  turn  the  pointers, 

•  Since  this  paper  was  written  I  received  a  letter  from  Mr.  Perrot,  which  lias  been  feen  by  the  Prefidcnr, 
containing  the  following  paffage. 

"  I  pcrfeftly  recoUeft  having  feveral  converfationt  with  you  in  t^(>7,  on  the  fubjtft  of  a  fpeedy  and  fecrer 
"  conveyance  of  intelligence  t  I  recolleft  our  going  up  the  hills,  to  fee  how  far  and  how  diftinftly  the  arms 
«' (and  the  pofition  of  them)  of  Ntttlebed  windmill  werc^  to  be  difcovered  with  cafe.  As  to  tlie  experiments 
'y  from  Highgate  to  London,  by  means  of  lamps,  1  was  not  prefent  at  the  time  ;  but  J  remember  your  mentinn- 
"  ing  the  circumftance  to  me,  I  believe  in  the  fame  year.  All  thefe  particulars  were  brought  very  ftrongly  to 
'•my  memory,  when  the  French  a  few  years  ago  conveyed  intelligence  by  fignals;  and  I  then  thought  and 
"  declared,  that  the  merit  of  the  invention  undoubtedly  belonged  to  you. ---I  am  very  glad  that  I  have  it  in 
"  my  power  to  lend  you  this  confirmation,  bccaufe  I  imagine  there  is  no  other  perfon  now  living  who  can  wit- 
"  nefs  your  obfervations  in  Berkihire."' 

f  I  infcrr,  Plate  xiii.  fig.  »•  a  line  defcrjbed  by  telegraphs  as  an  example. — It  is  the  firft  lineof  thefallowins- 
verfes,  written  on  the  profpeft  of  correfponding  between  England  and  Ireland  by  the  Telegraph  : 
Hark  from  Bafaltic  rocks  a^d  giant  walls. 
To  Britain's  (bores  the  glad  Hibcrnia  calls; 
Her  voice  no  longer  waits,  retarding  tides. 
The  meeting  coafls  na  more  the  fea  divides. 
Quick,  at  the  voice  of  forttinc,  or  of  fame, 
Kindles  from  fhore  to  fbore  the  patriot  rtamc ; 
Hov'rin"  in  air,  each  kindred  genius  I'miles, 
And  binds  with  clofer  bands  the  filler  iije.4. 
The  numbtrs  are,  4645,  2331,  573>  >"3>  *44'  '4")  ^il^- 

which 


On  the  Art  of  eonvtying  Secret  end  S^vi/t  Inielligetice.  ^VL 

wliicfi  are  fixed  in  their  different  pofitions  by  a  catch  or  alidad.  By  means  of  the  platform, 
the  piimter  may  be  turned  to  any  part  of  the  compafs;  and  as  one  fide  of  it  is  painted 
black  and  the  other  white,  either  fide  may  be  employed,  as  th^  colour  of  the  clouds,  or  the 
Ctuation  of  the  place,  may  require. 

Befides  thefe  permanent  machines,  of  which  dimenfions  and  a  defcription  are  fubjoined 
in  plate  xiii.  I  make  ufc  of  portable  machines,  (which  may  be  detached  like  tentacula  from 
the  main  body  in  hazy  weather,)  confiding  of  pointers  ten  or  twelve  feet  high,  and  of  a 
light  triangular  (land,  which  can  be  eafily  fattened  with  tent  pegs  to  the  ground :  thefe  may 
be  lodged  i;i  any  houfe  near  the  place  where  they  are  ufed,  or  in  times  of  danger  may 
be  carried  bsck  to  the  permanent  ftations  every  night. 

In  managing  a  correfpondence  by  thefe  machines,  it  is  neceflary  to  have  certain  fignals- 
eflabliflied :  nor  are  thefe  fignals  merely  arbitrary ;  it  is  abfolutely  neceflary  that  they 
fhould  be  made  by  the  two  external  or  by  the  two  internal  pointers,  elfe  they  could  not 
be  repeated  by  the  intermediate  flations  without  confufion  ;  becaufe,  in  the  middle  flations, 
that  pointer  which  reprefents  thoufands  when  conveying  a  mefiage  eaftward  for  inftartce,. 
mult,  when  anfwer  is  returned  in  an  oppofite  dlredion,  reprefent  units  ;  the  fame  change 
will  take  place  between  the  pointers  that  denote  hundreds  and  tens. 

Certain  hours  of  the  day  muft  be  appointed  for  ordinary  communication.  Suppofe 
ten  o'clock  in  the  morning,  and  five  in  the  afternoon  in  fummer.  Every  communication 
begins  from  the  capical.  If  no  intelligence  is  required  to  be  conveyed  from  thence,  the 
word  BEGIN  is  fent  to  the  county  ftation,  which  may  then  proceed  or  difmifs  the 
meeting. 

When  any  communication  is  to  be  commenced,  the  pointers  that  denote  thoufands  and 
units  are  whirled  round,  till  the  fame  is  done  at  the  correfponding  ftation.  When  this 
fignal  has  been  anfwered,  the  perfon  who  gave  it  proceeds  to  fend  his  intelligence.  As 
foon  as  he  begins,  the  pointer  of  hundreds  at  the  oppofite  ftation  is  turned  to  two,  and 
kept  in  that  pofition  till  the  word  is  made  out  from  the  vocabulary}  it  is  then  turned  up 
to  O  or  Zero.  The  perfon  who  is  fpeaking,  when  he  perceives  by  this  fignal  that  he  is 
underftood,  turns  all  the  machines  to  nought,  wliich  is  always  to  be  done  at  the  conclu- 
fion  of  every  word. 

When  all  his  machines  are  in  this  pofition,  his  correfpondent  again  turns  his  pointer  be- 
longing to  the  place  of  hundreds  to  two,  where  it  is  to  remain  till  he  receives  another  word,, 
and  fo  on  till  all  that  is  meant  to  be  faid  is  finifhed.     To  denote  that  his  communication^ 
is  finifhed  * — thousands  and  units  are  to  be  vibrated  backwards  and  forwards  with 
the  point  downwards  like  a  pendulum,  till  the  fame  is  done  at  the  oppofite  ftation. 

If  any  interruption  takes  place  on  either  fide,  from  a  cloud,  a  fliower,  or  any  accident,, 
it  is  pointed  out  by  vibrating  thousands  and  units  with  their  points  upwards;  which 
fignal  muft  be  repeated  from  the  oppofite  ftation.     Whoever  has  made  the  fignal  of  inter- 
ruption, muft  make  a  fignal  of  recommencement,  when  he  is  ready  to  proceed,  by  vibrating: 
HUNDREDS  and  TENS,  wlth  their  points  upwards;  when  this  is  anfwered  (but  not  before,) ' 

*  I  ufe  the  words  Thoufands  and  Units  here,  and  in  the  reft  of  this  defcription,  for  the  ppinters  or  machines 
tliat  ftand  in  tlve  nuiperical  place  of  thoufands  asd  units, 

the.; 


^1*  -t)/;  the  Art  of  conveying  Secret  and  Swift  Intelligent. 


<^.^ 


<lie  biifinefs  may  proceed.     It  (hould  be  obferved  in  generd,  that  every   fignal  flionld  T>e 
•wnfwered. 

It  requires  fome  fteadinefs  to  abide  by  thefe  iignals;  but  if  they  are  patiently  adhered  to, 
the  fuccefs  that  they  enfure  will  foon  convince  the  operator  of  their  utility.  Without  them 
every  thing  would  be  in  confufion  ;  by  their.  interpoCtion,  perfpicuity  and  order  are 
perfedlly  enfured. 

In  my  firfl  experiments  the  impatience  of  friends  who  Were  prefent,  was  forcetimes  fo 
great  as  to  make  it  very  difficult  to  adhere  to  previous  arrangements  ;  but  a  very  little 
practice  (I  mean  the  praftice  of  five  or  fix  days)  reduced  the  routine  of  communication  to 
as  much  facility  as  could  be  defired,  fo  that  a  word  (or  a  fcntence,  if  contained  in  the  vo- 
tabulary)  could  be  fent  in  twenty  feconds. 

Any  perfon  who  has  the  flighted  tafte  for  fcience  or  literature  mud  be  druck  when  he 
fees  inflantaneous  interpretation  of  fignals  which  arc  made  at  the  diflance  x)f  fifteen  or 
•twenty  miles,  and  when  he  perceives  the  power  which  is  obtained  of  tranfmitting  thought 
•w  ith  fuch  aftonifliing  rapidity. 

I  fhall  not  enter  into  a  detail  of  the  fignals  which  are  necefiiiry  for  intermediate 
ftations  -,,  it  would  take  up  fome  time  to  explain  them,  and  they  will  readily  occur  froiB 
•what  has  been  faid  already. 

Wha:  I  have  hitherto  defcribed  relates  to  a  large  and  permanent  eftablifliment  *  ;  for 
•the  management  of  which  one  man  is  required  at  each  pointer,  one  at  the  tekfcope, 
•and  another  at  the  vocabulary  ;  but,  foT  ordinary  purpofes,  a  fingle  pointer,  with  one  man 
to  work  it,  and  another  at  the  telefcope,  with  a  fmaller  vocabulary,  are  fufficient.  With 
this  reduced  apparatus  we  can  with  cafe  fpcak  at  the  rate  of  one  *ord  per  minute  to  a 
great  diftance,  as  the  time  loft,  by  intermediate  ftations  Is  but  fmall. 

The  vocabulary  corrcfponding  with  the  numbers  denoted  by  this  machinery,  is  com- 
pofed  of  a  large  book  with  mahogany  covers  framed,  to  prevent  them  from  warping.  Its 
fize  is  forty-feven  inches  by  twenty-one  ;  it  confifts  of  forty-nine  double  pages,  that  is  to 
fay,  each  fheet  is  folded  in  the  middle,  where  it  opens  from  one  page. 

The  book  is  divided  into  feven  parts,  confiding  each  of  feven  pages,  by  thin  flips  of  ma- 
hogany, which  ferve  to  open  it  eafily  at  each  of  thefe  divifions.  Every  one  of  thefe  feven 
divifions  contains  feven  pag-es,  and  each  page  contains  forty- nine  words. 

No  more  than  forty-nine  words  are  contained  in  a  page,  becaufe  the  numbers  of  8  and 
0,  and  Zero,  are  omitted.  This  omiffion  arifes  from  the  ftrudure  of  the  machinery, 
which  points  only  to  feven  numbers,  referving  O  for  a  point  of  reft,  at  which  point  th« 
Hands  indicate  nothing.  In  every  hundred,  therefore,  only  forty-nine  numbers  are  ufed; 
and  in  every  thoufand  only  feven  hundred  is  counted.  Each  divifion  of  the  book  feparated 
by  the  mahogany  rulers,  contains  all  the  efficient  numbers  in  feven  hundred.  Each  of 
thefe  rulers  projefts  (Plate  xili.  fig.  3.)  beyond  the  fides  of  the  pages,  and  each  is  num- 
bered in  fucceffion  from  one  to  fev-en  ;  and  they  are  fo  placed  below  one  another,  as  to 
permit  the  numbers  on  all  fides  of  them  to  be  feen  at  once,  as  in  plate  xiii. 

When  any  number  of  thoufands  is  pointed  out,  it  can  by  means  of  thefe  rulers  be  im- 

•  The  houfe  belonging  to  this  eftablifoment  might  be  made  tenable  againft  a  mob,  or  mufquetry,  at  a  fma|l 
(xpence,  by  port  flankers  of  elm  or  aih  adapted  occafionally  to  the  windows.     See  plate  xiii.  fig.  4. 

mediately 


On  the  Jrt  of  conveying  Secret  and  Swift  Inielligenct.'  "'  32 j 

mediately  felefted  ;  the  ferie&of  feveh  pages,  which  one  of  thefe  rulers  opens,  is  cut,  liice 
the  alphabet  of  a  ledger,  at  the  edge  in  feven  divifions.  By  thefe  means  the  page  con- 
taining the  hundred  which  is  wanted,  is  inltantly  found..  In  the  page  thus  found  the 
tens,  from  ten  to  feventy  inclufive,  are  divided  from  each  other  fo  as  to  be  inliantly.dif- 
tinguifhable,  and  the  units  under  each  diviiion  are  in  like  manner  eauly  felefled. 

Plate  III.  is-a  fpecimen  of  the  firft  page  of  the  vocabulary ;.  and  though  it  is  but  one- 
fifth  of  the  real  fize,  it  is  fufficiently  diitinft.  It^  is  divided  into  eight  clafTes  f  ail  the: 
dalles  are  numbered  downwards  feriatim  from  i  to  77,  omitting  cyphers  or  zero,  and 
eights  and  nines.  When  once  the  clafs  required  is  afcertained,  any  number  on  the  page 
can  be  found  immediately :— As  for  inftance,  the  reader  will  cafily  fcle£t  clafs  iv. . 
number  36^,  or  clafs  vii.  number  77,  and  fo  of  the  refL 

Nothing  remains  to  be  explained  but  the  manner  in  which  the  clafs  in  each  page  Is 
pointed  out  by  the  machinery.  For  this  purpofe,  before  the  pointers  are  turned  to  any  fet 
of  figures,  the  polfiter  that  reprefents  thoufands  is  turned  to  the  claf,  that  is  wanted  ;  as 
foon  as  the  correfpondent  anfwers  this  fignal,  thousands  is  returned  to  O,  and  inftantly 
all  the  pointers  are  moved  to  the  places  which  denote  the  figures  required  for  any  word , 
or  fentence. 

When  the  cl&fs  is  thus  afcertained,  an  index,  which  fiides  on'  the  mairogany  covcp  of 
the  book,  is  fet  to  the  column  belonging  to  this  clafs;  the  nunbr  of  thoufands  is  then: 
opened  by  the  ruler,  as  foon  as  it  is  read  off  by  the  teiefcope  ;  the  number  of  hundreds 
IS  opened  by  the  pages  when  they  are  cut  away,  and  the  number  of  tens  and  units  is  feen. 
on  the  page.  As  the  pointers  are  moved  in  fucceffion  from-thoufands  to. unito,  the  dif- 
ferent divifions  of  the  book-  can  be  opened  as  fait  as  the  pointers  are  moved..  The  order 
of  this  book  might  be  reverfed  with  apparent  advantage,  by  dividing  the  bsok-into  clafles 
by  the  mahogany  rulers,  &c.  Uut  I  prefer,  for  reafons  which- it  would  bs  tedious  to  infill 
upon,  the  arrangement  which  I  have  followed. 

As  fecrefy  is  an  obje6l  of  the  greatell  confequence,  I  (half  endeavour  to  point  out  in  a 
few  words  the  fuperiority  of  this  mode  of  communication  over  any  alphabetical  arrange- 
ment, not  only  in  point  of  expedition,  but  of  concealment. 

Although  the  common  alphabet-may  be  varied  at  pleafure,'  and  any  arbitrary  figns.may 
be  employed  to  convey  the  powers  of  each  letter,  yet,  by-certain  rules,  any, of  thefe  arrange- 
ments may  be  deciphered.  Whoever  fees  the  movements  of  the  French  telegraph. (I'mean 
of  that  which  is  commonly  known  as  fuch)  may  unfold  the  intelligence  which  it,  conveys, 
by  merely  marking  down  the  changes  which  he  fees,  and  putting  them  into. the  biiads  of 
a  decipherer.  The  rules  for  deciphering  depend  upon  the  ufual  arrangements  bf  letters. 
In  our  language  a  fingle  letter  my  ft  be  A  or  I.  The  proportions  which  exift  between 
words  of  one,  two,  thrccj  and  any  greater  number  of  letters,  are  clafled  in-  catalogues; 
and  from  thefe  the  monofyllables  of  any  cipher  are  eafily  obtained,  and  from  the.  letters 
of  thefe' menofyllables  the  letters  of  longer  vfords  are  difcovered.  By  fimilar  rules,  fomc 
of  which  are  very  ingenious,  and  which  depend  upon  the  general  philofophy  of  language, 
any  alphabetical  cipher  may  be  e;ifiiy  unfolded.  But  thefe  rules,  except  a  very  fewof  them^ 
are  ufelefs,  when  we  employ  ciphers  which  denote  entire  words.  Here  the  moll  obvious 
means  of  difcovety  may  be  avoided,  by  omitting  thofe  common  words  which  occur  fo 
frequ'titly  in  every  language,  the,  and-,  that,  to,  &g.  But,,  fuppofing  that  from  its. fre^ 
aijent.iccurrepce  any  particular  word  ihould  be  difcovered,  no  progrcfs  can  be  made  from 

tkefft. 


,J»4  ''0»  tin  Art  of  cmveyitig  Secret  and  Smlp  Intel/igf»ee. 

thcfe  data.  The  cipher  of  each  word  is  an  ifolatecL  fa£t,  which  teads  to  nothing  farther. 
Suppofe  the  knowledge  of  any  panicuhir  vocabulary  AkmiM  fall  into  han'd«  for  which  it 
was  not  intended,  a  flight. change  in  the  numeration,  without;  any  aflual  change  of  the 
figures,  would  entirely  prevent  difcovery :—- For  inftance,  if  die  Lord  Lieutenant  wiflied 
to  fend  orders  to  the  Commander  in  Chief ;  if  he  made  ufe  of  the  numbers  written  in  the 
vocabulary  in  one  day,  he  might,  after  previous  communication,  employ  a  different  nu- 
meration by  ordering  that  i  (for  inflance)  fliouul  be  added  to  every  figure.  If  clafs  ii. 
number  3664,  ftood  in  the  vocabulary  for  gunpowder  by  the  addition  which  I  have  pro- 
pofed,  the  number  would  ftand  clafs  iii.  number  4775,  which  might  mean  a  crocodile,  or 
'I  ippoo  Saib,  or  any  thing  foreign  to  the  real  word.  Gy  fimilar  provifions  any  number  of 
feparate  correfpondents  might  carry  on  a  mutual  intercourfe,  without  interfering  with  one 
another. 

In  the  courfe  of  twelve  months  I  tried  a  great  number  of  experiments^  and  carried  on 
a  great  number  of  converfations  with  the  tellograph  ;  of  all  thefe  a  regular  journal  has 
been  kept,  containing  what  was  unfuccefsful,  as  well  as  what  fucceeded.  If  fuch  journals 
were  kept  in  the  profecution  of  philofophical  puifuits,  they  would  pay  for  the  trouble  of 
keeping  them  by  the  accuracy  of  the  experience  which  they  enfure. 

I  fhall  not  at  prefent  enter  into  any  detail  of  my  No6turnal  Tellograph.  Its  velocity 
far  exceeds  what  can  be  done  by  day,  as  in  clear  weather  flations  at  fifty  miles  diftancc 
may  be  plainly  diftinguiflied. 

When  this  paper  was  firfl  prefented  to  the  Academy,  I  had  determined  to  try  an  expe- 
riment acrcfs  the  Channel  from  Donaghadee  to  Port- Patrick.  I  was  ambitious  of  being 
the  firft  perfon  who  (hould  conneft  the  iflands  more  clofely,  by  facilitating  their  mutual 
Intercourfe.  Public  bufinefs  prevented  me  from  going  to  the  fea-fide  at  the  time  I 
had  intended,  and  from  carrying  on  a  feries  of  converfations  by  day  and  night  be- 
tween the  two  kingdoms ;  but  Mr.  Lovell  Edgeworth,  my  fon,  had  the  fatisfa£lion  of 
fending  four  mefTages  acrofs  the  Channel  at  four  o'clock  P.  M.  on  the  24th  of  Augufl 
1795,  and  of  receiving  immediate  anfwers  before  a  vaft  concourfe  of  people.  The  ma- 
chines by  which  this  communication  was  made,  were  thirty  feet  high,  and  fifteen  feet  at 
the  bafe.  A  child  of  four  years  old  could  turn  them.  Mifly  weather  prevented  them 
from  being  feen;  but  when  the  weather  cleared  up,  a  pointer  of  twelve  feet  high  could 
have  been  plainly  diflinguifhed  acrofs  the  Channel. 

Though  I  have  beftowed  much  attention  and  labour  upon  this  fubjeft,  I  do  not  pretend 
to  fay  that  the  means  of  tellographic  communication,  which  I  have  invented,  arc  the  beft 
that  can  be  devifed.  Imitations  without  end  may  be  attempted;  pointers  of  various  fhapes 
and  materials  may  be  employed  ;  real  improvements  will  alfo  probably  be  made;  and,  per- 
haps, new  principles  may  be  adopted.  1  he  varieties  of  art  are  infinite,  and  none  but 
perfons  of  narrow  underftanding,  who  feel  a  want  of  refources  in  their  own  invention, 
are  jealous  of  competition  and  difpofed  to  monopolize  diftoveries.  The  thing  itfelf  mufl 
fooner  or  later  prevail,  for  utility  convinces  and  governs  mankind  ;  and  however  inatten- 
tion or  timidity  may  for  a  time  impede  its  progrefs,  1  will  venture  to  predift,  that  it 
will  at  fome  future  period  be  generally  pra£lifed  not  only  in  thefe  iflands,  but  that  it  will 
jn  time  become  a  means  of  communication  between  the  moft  dillant  parts  of  the  world, 
wherever  arts  and  fciences  have  civilized  maakind. 

TABLE. 


[     32S    ] 


SPECIMEN   OF    THE   VOCABULARY 

BELONGING     TO 

MR.    EDGE  WORTH'S    TELLOGRAPH. 


Common  Words. 

Words  lefs  common. 

Technical  Terms,  c.  n.  m. 

Perfons. 

Clals  o. 

Clafs  I. 

Clafs  z. 

Clafs  3. 

I. 

I. 

I. 

I. 

11  A 

II   Abafe 

II   Aback 

II  Abbot 

12   Ab 

12  Abate  , 

12  Abacus 

12  Ackland 

13  Ac 

I J  Abbey 

13  Abaft 

13  Adon     . 

14  Ad 

14  Abbefs 

14  Abatis 

14  Achefon 

15  Ae 

1 5 .  Abbot 

1 :;  Abdomen 

i_5  Adams 

16  Af 

16  Abdicate 

16  AbduAor 

16  Adamfon 

17   Ag 

2. 
21  Ah 

17  Abed,  Abet 

17  Abeal 

17  Adair 

2. 

21  Abide 

2* 

2  1  Aberration 

2. 

21  Adolphus 

22   Ai 

22  Abjure 

22   Abeyance 

22  Addington 

23  Ak 

23   Ablative 

23  Ablution 

23  Ahmuty 

24  Al 

24  Able-bodied 

24  Abortion 

34  Aikin 

25  Am 

25  Abolirti 

25  Abreaft 

25  Alcock 

26  An 

26  Abcinlnation 

26  Abrogation 

<6  Aldridgc 

27  Ap 

27  Abortive 

27  Abfcefs 

27  Allot 

3- 

3- 

3- 

3' 

31  Aq 

31    Above-all 

31   Abfcia 

31  Alley 

32  Ar 

32  Above-board 

32  Abfcenthium 

32  AUett 

33  As 

33  Above-mentioned 

33  Abforbent 

33  Allen 

34  At 

34  Abridge 

34  Abforptlon 

34  Alder 

35  Av 

35  Abridgement 

35  Abftergent 

35  Alexander 

36  An 

36  Abruptly 

36  Acacia 

36  Amyatt 

37  Aw 

37  Abfentee 

37  Academic 

37  Ambrofe 

4- 

4- 

4- 

4- 

41  Ay 

41   Abfolve 

41  Acantlia 

41  Anderfon 

42  Ax 

42  Abfolution 

4a  Accretion 

42  Andre 

43  Az 

43   Abforb 

43  Acefcent 

43  Andrew* 

44  Abandon 

44   Abftraft 

44  Acetous     .' 

44  Ar.gel 

41;  Abiife 

4?    Abflrufe 

45  Achromatic 

45   Anger 

46  Abhor 

46  Abfurdly 

46  Acids 

46  Annefly 

47  Abjed 

47  Abyfs 

47  Acidity 

47  Annefdale 

.     5- 

5- 

5- 

S- 

51    Abibty 

51  Academy 

51  Acme 

51  Antrim 

52  Able 

52   Accelerate 

52  Aconite 

52  Anfon 

53  Above 

53  Accent 

53  Acouftics 

53  Anftruther 

54  Abound 

54  Accefs 

54  Acroih'c 

54  Antonle 

55   About 

55   AccefTary 

55  Adamant 

^;  Anthony 

56  Abiiiidance 

56  Acceflible 

56  Adder 

56   Alfred 

57   Abroad 

57  Acclamation 

57  Adder's-tonaue 

57  Alphonfuj 

6. 

6. 

6. 

6. 

61   Abrupt 

61  Accommodate 

61   Adduftor 

6t  Amadeus 

62  Abfent 

62  Accomplice 

62  Adelphi 

62  Anne 

63  Abfence 

63  Accofl 

63  Adcs 

63  Anfolm 

64  Abfolute 

64  Accountant 

64  Adit 

64  Appleby 

65   Ablbin 

65  Account-book 

65  Adjutant 

65  Apfley 

66  Abfurd 

66  Accretion 

66  Adnata 

66  Archer 

67  Abflain 

67  Accrue 

67  Adonis 

67  Auftin 

7« 

7-  , 

7-  . 

7- 

71   Abiife 

71  Accumulate 

71  Adofculation 

71  Archdale 

72  Accede 

72  Accufative    ' 

72  Adracanth 

72  Arran,  Ld. 

73  Accept 

73  Ace 

73   Adrift 

73  Archdall 

74  Acceptable 

74  Achieve 

74.  Advancc-fofTe 

74  Afhe 

75  Accident 

7  5  Acquifition 

7  5   Advance-gua  rd 

75  Atkinfon 

76  Accompany 

76  Acquittance 

76  Advancement 

76  Aylward 

77   Accomplifh 

77  Acre 

77  Advcrtifement 

77  Ayre 

Vol.  11.— Oct.  1798. 

I 

Ju' 

[    3i6    ] 


Officers. 
Chifc  4. 


Places. 
CLils  5. 


N.ivy  aadMerchaiit  Ships! 
CUls  6. 


Pliralcs  aiu!  Ssiitentes. 
CJafs  7. 


I. 

li   Academyoflnfcriptions 

12  Academy  of  B.L.  Paris 

13  Academy 

14  Account  Office 

1 5  Admiralty 

16  Agent  to  the  — 

17  Admiral 

2. 
21  Adjutant 
2  2   Alderman  of  Briftol 

23  Alderman  of  Cork 

24  Alderman  of 

25  Arclideacon  of  — 

26  —  Ardagh  — 

27  — Ardfert  — 

3- 

31  —  Armagh 

32  —  Acowry 

33  —  Aghadoe 

34  —  Clogher 

35  —  Clonfcrt 

36  —  Cloyne 

37  —  Connor 

4- 

41  —  Dublin 

42  Archbiftiop  of — 

43  —  Dublin 

44  —  Armagh 

45  —  Calhel 

46  —  Cock 

47  —  Canterbury 


5» 
52 
53 
54 
$5 
S6 
57 


—  Tuam 

—  York 
Admiral  of 

—  the  Fleet 

—  the  White 

—  ditto  I 

—  ditto  2 


6, 

61  —  ditto  3 

62  —  ditto  4 

63  —  ditt..  5 


—  ditto  6 

—  ditto  7 
ditto  8 
ditto  9 

7- 

—  ditto  I  o 

—  ditto  1 1 
Admiral  of 

the  Blue 

—  ditto  I 

76  —  ditto  2 

77  —  d;tto  3 


64 

6; 
66 
67 

7' 

72 
73 

74 
75 


1 1  Abbeville 

12  Aberdeen 

13  Abergavenny 

14  Abiiigton 

15  Abydos 

16  AbyfTuiia 
I  7  Acadia 


21 

Acauiboo 

22 

Acipulca 

2l 

Acam 

24 

Ajda 

2; 

Adrianople 

26  iEtna 

27 

Africa 

3- 

^i 

Aa;incourt 

^2 

AixlaChapellt 

33 

Albany 

34 

Alcantara 

3? 

Aleppo 

^6 

Alcxa'idria 

37 

Algiers 

4- 

41 

Alicant 

42 

Ali.^s 

43 

Alfacc 

44 

Antrim 

4? 

Aylefbury 

46 

Avrfllire 

47 

All  Saints 

<;i 

Alnwick 

•la 

Aluft 

S3 

Alresford 

"J-t 

Aldborough. 

.S9 

Alen<;on 

s& 

Andes 

57 

Anglcfey 

6. 

61  Angola 

62  Anjou 

63  Anhalt 

64  Antioch 

65  Aitwerp 
6)  Archangel 
67  Argenton 

7- 

71  A'lierflone 

72  Ai'-'ee 

73  A.  klowr 

74  Armagh 

75  Athcnry 

76  Atiilow 

77  Athy    . 


11  Aths 

12  Ajjx 

13  Albiori 

14  Africa 

J  5   Audacious 

16  Agamcmnc 

17  America 

2. 

Anion 
Alcide 
A   xaiider 
Alfred 
Arrogant 

26  Alia 

27  Ardent 

3- 

31  Achdles 

3  1  Adamant 

33  Afilltance 

34  A:teon 

35  ^rgo 

36  Arto  s 

37  AfFiirance 


41 

42 
43 
44 
4S 
46 


4» 
Arethufa 
MAas 
Adive 
Alarm 
Amazon 
Ambufcade 


47   Amphion 


5' 

52 
53 
54 
^5 


,  5 

Apo'lp 

Allrea 

Alcmene 

Andromache 

Albemarle 

Aurora 


57  Amphitrite 


6: 
62 
63 

64 

65 
66 


6. 

Ariadne 

Alfred 

Atalanta 

Ariel 

Allegiance 

Albany 


67  Alderney 

7' 

7 1  Alert 

72  Alligator 
7?  Avuigcr 
71  ^na 

75  Alcdlo 

76  Aquillone 

77  Argus 


1 1    Attend  to-day  at  A,  M. 
at  P.  M. 


—  tomoiiow  at  A.M. 
at  P.  M. 


—  to-night  at ' 

—  to-moi  row  niglit  at  ~ 

—  on  iVlonday  at  A.M. 

2. 
at  P.  M, 


•  on  Turldayat  A.M. 
at  i'.  M. 


■  on  Wcdncld^yatA.M.. 
at  P.  M. 

■  on  Ttiurldav  at  A.  M,, 
at  P.  M. 


3- 
■  on  Friday  at  A.M. 

at  P.M. 


•on  Saturday  at  A.  M. 
at  P.M. 


12 
'J 
14 

'5 

16 

17 

2t 
22 

23 
24 

25 

26 

27 

3' 

32 
33 

■4 

35    Alarming  Intelligence  13  re- 
ceived trom  — 

37  Acquaint  the  Commiffioner'si 
Officers  at  — 
4. 

41   — principal  Magiflratesat —^ 

4     — the  High  Shei  iff  at — .. 

43  —  the  Secretary  of  \Var 

44 of  State 

45    Agreeable  to  the  Orders  of  hv». 
M:ijclly 

47  —oi  tiie  Lord  Lieutenant. 


51  —  of  Government 

52  —  of  the  Commanding  OfHterj 

at  — 
^c^  — of  the  Magillrite  of  — 
54' Agreeable  to  your  Orders 
5  5  All  is  well 

56  Alter  yourTelegraphs  to  Black; 

57  ■ to  White 

6. 

61  Admit  no  S' rangers 

62  Admiralty  hus  ifl'iied  Orders- 

63  -.-  has  received  Intelligence    ■ 

64  Arms  been  found  hidden  at  — . 

65  Army  approaches  in  Number 

66  An  armed  Mob  at  — 

67  Art.  of  Capitulation  agreed  to, 

.  7-      . 

71  AfGftance  is  required  at — 

72  Appearances  arc  againll .— .^ 

73  Anlwer  my  lall  to-morrowr 

74  .VrriveJ  fiuce  my  lalt  at  — 

7  ;   Arrived  N<  ws  from  E.  Indies 
7b  Ai  rived  Mails  from  — 
y7  Agreeable  Intelligence  is   IC.- 
ceived 


tlefcriptlon  of  a  Portable  Telegraph,  ,  J2.^ 


SUPPLEMENT. 


S, 


'INCE  the  Royal  Irifh  Academy  did  me  the  honour  to  accept  of  my  eflay  on  the  Tele- 
graph, I  have  made  material  improvements  in  its  conftrui^ion,  which  I  think  it  my  duty  to 
communicate. 

In  September  i79<5,  the  Lord  Lieutenant  ordered  me  to  prepare  Telegraphs  for  an  expe- 
riment before  his  Excellency.  In  confequence  I  con(lru£ted  four  new  Telegraphs. — I  had 
found  that  the  large  machines  thirty  feet  high,  with  which  my  fons  talked,  in  September 
1794,  acrofs  the  channel  between  Ireland  and  Scotland,  were  liable  to  accidents  in  ftormy 
weather :  my  firft  confideration  therefore  was  to  contrive  fome  means  of  furling  their 
canvas  when  they  were  not  in  in  ufe  ;  and,  from  the  rigging  of  fliips,  it  was  obvious  that 
cordage  was  for  this  purpofe  preferable  to  inflexible  braces  of  wood.  I  therefore  adopted 
die  following  conflruftion  : 

A.  (fig.  4.  Plate  XIV.)  a  hollow  axle-tree  made  in  feparate  pieces  hooped  together  in 
the  form  of  a  double  truncated  cone,  on  the  middle  of  which  is  faftened  a  wheel  of  wood 
(b,  fig.  4)  with  eight  notches  cut  out  (a,  fig.  4)  to  receive  eight  ribs  (r.  r.  r.  r,  r.  r.  r.  r 
fig.  I  and  2.)  Thefe  ribs  turning  on  a  ftrong  iron  ring,  fhut  up  like  the  ribs  of  an  um- 
brella, and  are  raifed  and  adjufted  by  cords  paffing  through  eight  holes  in  the  flanches  or 
fhoulders  (F  fig.  I.  4.)  Thefe  flanches  and  tliofe  at  (f.  fig.  2  and  4)  ferve  to  keep  the 
machine  in  its  place  upon  the  ftands  which  fupport  it  (fig.  2) ;  the  cords  are  drained  and 
faftened  like  the  cords  of  a  tent  (c.  c.  &c.  fig.  2.) 

Where  permanent  buildings  are  not  required,  fupports  for  thefe  machines  may  be  con- 
ftrudled  in  the  following  manner.  Two  ftands,  each  of  them  made  of  two  pieces  of  wood 
fimply  bolted  together,  as  (fig.  3 ),  muft  be  ere£l:ed,  and  held  fteady  by  means  of  cords  (c.  c.) 
faftened  to  common  tent  pegs,  as  in  (fig.  2  P.  P.  P.)  When  the  machines  are  large,  fmall 
piles  fliould  be  ufed  inflead  of  pegs,  and  running  tackle  (t.)  fliould  be  ufed  both  for  the 
cords  of  the  pointers,  and  the  ftands.  A  number  of  minute  circumftances  Ihould  be 
attended  to  in  the  conftru£tion  and  ufe  of  thefe  machines  •,  but  I  do  not  think  it  proper  to 
detail  them  to  this  Academy ;  they  fhould  appear  in  a  different  place  *. 

Befides  rendering  the  Telegraph  fafe  againft  ftorms,  and  more  eafily  manageable,  I  found 
by  experience  that  one  machine  could  be  made  to  perform  the  fame  eflieft  as  four,  with  but 
little  lofs  of  time  ;  what  took  up  four  minutes  with  four  pointers,  can  be  conveyed  in  five 
mJnutes  by  one.  I  have  alfo  found  that,  by  anfwering  each  fignal  or  number  ftiown  at 
every  ftation,  all  poftibility  of  miftake  is  avoided. 

I  believe  that,  in  other  eftabliftimerits  of  this  fort,  it  has  been  found  that  thick  and  foggy 
weather  has  occafioned  more  interruptions  than  were  expedted.     With  my  Telegraphs,  I 

•  Formerly,  in  France,  every  engineer  who  condufted.any  public  work,  was  obliged  to  lodge  in  a  public  office 
exaft  drawings,  with  minute  defcriptions,  of  every  part  of  and  procefs  of  his  operations.  Numberlefs  fmall  im- 
provements in  workmanfliip  and  tools  were  prcferved  by  thefe  means,  and  by  degrees  were  coUedled  inta 
publications  of  general  circulation. 

I  was  required  to  deliver  drawings  of  all  the  machinery  I  employed  in  the  work  carried  on  at  Lyons'in  1772, 
for  turning  the  courfe  of  the  Rhone  : 

But,  in  the  tranfiftiont  of  a  literary  Society,  fuch  details  would  be  tedious  and  improper. 

U  u  2  hare 


Jit  Portable  Telegraph. — Scientific  Newt. 

have  good  reafon  to  aflert,  that  there  do  not  commonly  occur  above  eight  or  ten  days  in 
the  year  when  intelligence  might  not  be  conveyed  by  land. 

If .  eight  men  were  pofted  at  each  permanent  ftation,  at  the  diftance  of  eighteen  or 
twenty  Englifh  miles  afunder,  with  machines  of  twenty-five  feet  high,  in  h.izy  weather  they 
might  detach  two  men  with  portable  Telegraphs,  to  the  diftance  of  about  fix  miles  from 
each  Nation,  who,  with  eight  foot  Telegraphs,  could  keep  up  a  regular  communication. 

The  portable  Telegraph  refembles  that  which  I  have  defcribed  ;  it  differs  only  in  two 
circumftances  :  for  convenience,  as  it  is  fmall,  and  does  not  oppofe  much  furface  to  the 
wind,  it  may  be  diftehded  with  ribs  of  wood  inftead  of  cords. 

The  portable  Telegraph  which  my  fon  had  the  honour  of  fliowing  to  his  Royal  Highnefs 
the  Duke  of  York  in  Kenfington  gardens,  in  Oftober  laft,  was  furniflied  with  filken  cords, 
on  purpofe  to  fhew  how  my  larger  Telegraphs  were  conftrufted  ;  but  it  was  intended 
merely  for  reconnoitring  near  an  arniy,  and  was  only  fix  feet  high. 

In  the  eflay  which  the  Academy  has  already  received,  I  faid  that  imitations  without  end 
might  be  made  of  my  Telegraph.  Every  index  or  pointer  that  moves  circularly,  dividing 
an  imaginary  circle  into  parts,  and  denoting  figures  or  figns  that  correfpond  with  a  voca- 
bulary, is  founded  on  the  fame  principle  as  mine.  The  French  have  laid  afide  their  former 
clumfy  apparatus,  and  have  conftrufted  a  Telegraph  on  thefe  principles  ;  and  the  Admi- 
ralty in  England  have,  as  I  am  informed,  very  lately  done  the  fame. 

The  firfl;  pointers  I  employed  in  1767  were  windmill  fails.  I  then  tried  indexes  of  the 
(hape  (fig.  5.)  Fig.  8.  A  pointer,  like  a  fword-cutler's  fign,  was  recommended  to  me  by 
a  member  of  the  Academy,  as  a  fecond  or  additional  hand  to  move  on  the  fame  centre 
as  the  principal  hand.  But  a  triangle,  whofe  bafe  is  equal  to  half  its  fide,  is,  of  all  the 
figures  I  have  tried,  the  moft  diflindt. 

The  Night  Telegraph  remains  ftill  to  be  defcribed  ;  its  ufes  are  perhaps  more  extenfive 
than  thofe  of  the  Telegraphs  I  have  already  publiflied  ;  and  I  propofe  to  make  it  the  fubjeiSk 
of  another  paper  upon  a  future  occafion. 

The  art  of  conveying  fwift  and  fecret  intelligence  is  not  one  of  thofe  inventions  which 
attracts  attention  only  by  its  novelty ;  on  the  contrary,  I  am  convinced  that  it  will  be 
thought  more  valuable,  the  longer  it  has  been  fubmitted  to  the  teft  of  time  and  experience. 


SCIENTIFIC  NEWS,  AND  ACCOUNT  OF  BOOKS. 

Copenhagen,  y/^/_y  12,  1798. 


T, 


H  E  Royal  Society  has  propofed  the  following  Prize  Queftions.    The  Prize  for  each 
is  a  Gold  Medal,  value  one  hundred  rixdollars  (22I.  los.) 

I.  Hijlory.  What  nations  difcovered  America  before  the  Norwegians,  and  performed 
voyages  by  fea  to  this  part  of  the  globe  ?  How  far  did  the  Norwegians  extend  their  difco- 
veries  in  America,  particularly  to  the  fouthward  ?  What  conclufions  may  be  deduced  on 
thefe  points,  either  from  decifive  reafons  or  fimple  conje£lures,  from  the  writings  and 
monuments  which  flill  fuBfift,  fuch  as  forts,  buildings,  languages  and  traditions  ? 

II.  Mathematics.  To  find  the  funftion  of  all  the  quantities,  which  ferve  conjointly  to 
determine  the  magnitude  of  the  calorific  efie£t  of  every  combuftible  material  in  common 

ufe  i. 


Scknti/ic  News, -^Account  of  Boo^t.  329 

ufe  ;  fuch  as  wood,  turf,  and  pitcoal,  whatever  may  be  their  peculiar  charaftcrs  in  other 
rcfpe£ls.     The  required  equation  muft  be  determined  for  at  lead  four  different  cafes : 

Cafe  I.  Where  the  wood,  turf,  or  coal  is  burned  in  a  furnace  to  heat  a  certain  volume  of 
air,  as  for  example^  that  of  a  chamber. 

Cafe  2.  Where  the  heat  is  employed  in  producing  the  flate  of  ebullition,  in  a  fluid  pro- 
per to  boil  certain  fubflances  plunged  in  it. 

Cnfe  3,,  Where  the  heat  is  employed  to  harden  foft  matters,  fuch  as  clay  for  tiles. 

Cafe  4.  And  where  certain  hard  or  confidant  matters,  fuch  as  metals,  are  required  to 
be  liquified  by  heat  in  a  furnace  or'forge.  Each  of  thefe  equations  grounded  on  various 
experiments  muft  be  found  and  eftabliftied  analytically,  fo  that  it  may  be  poffible  to  deter- 
mine with  precifion  the  ratio  of  the  calorific  efFeft,  and.confequently  the  degree  of  utility^ 
in  economical  applications  of  every  kind  of  wood,  turf,  or  pitcoal.     . 

III.  Natural  Philcfophy. — To  find  by  experiment  the  greateft  degree  of  heat  which  water 
in  the  ftate  of  vapour  can  communicate  to  other  bodies  ;  and  to  anfwer  the  queftion,  whether 
that  part  of  the  water  in  Papin's  digefter,  which  is  not  converted  into  fteam,  can  acquire 
a  more  elevated  temperature  than  21 2"  of  Fahrenheit. 

IV.  Philofophy. — What  are  the  moft  remarkable  degrees,  through  which  pra6llcal  philcfo- 
phy has  palled  from  the  time  in  which  it  was  firft  treated  fyftematically  to  the  prefent  time. 

The  memoirs  in  anfwer  to  thefe  queftions  are  required  to  be  written  in  Latin,  Danifh, 
or  German,  and  fent.  before  the  end  of  June  1799)  to  the  Secretary  of  the  Society, 


Profeflbr  Abilgaard. 


Berlin,    " 
The  Phyfical  Society  at  Berlin  has  announced  the  following  Queftion,  for  a  Prize  of  20 

Holland  Ducats.  (9I.  5s.) 
ADMITTI NG  that  Eledricity  is  a  neceflary  Agent  for  the  formation  of  Hail,  are  there 
any  grounds  for  concluding,  that  the  Eleftrical  Cloud  can  be  rendered  incapable  of  gene- 
rating Hail,  as  Lightning  is  prevented  by  Conduftors  ?  What  are  the  means  to  be  adopted 
for  this  purpofe,  and  the  fa£ts  or  obfervations  in  general  upon  the  fubjedl  which  deferve 
notice  ? 

Proceedings  of  the  Aflbciation  for  promoting  the   Difcovery  in  the  interior  Parts  of 

Africa,  &c. 
Abftraft  of  Mr.  Park's  Travels.     [Continued  from  page  283.] 

INFORMATION  of  a  confiderable  river  flowing  through  the  centre  of  Africa,  be- 
tween the  latitude  of  15°  and  2C°  north,  had  been  received  at  very  early  periods  from  differ- 
ent quarters,  which  at  difl^erent  times  was  fuppofed  to  be  part  of  the  Senegal  and  of  the 
Gambia.  Further  enquiries,  however,  though  they  confirm  the  ancient  accounts,  (hewed 
that  this  river  was  not  only  of  greater  magnitude  than  either  the  Senegal  or  Gambia,  but 
flowed  in  a  contrary  direction,  running  not  to  the  weftward  into  the  Atlantic,  but  from 
weft  to  eaft,  to  regions  unknown.  The  Moors  defcribed  it  by  the  name  of  Nil  il  Abeed,  or 
tlie  River  of  Slaves :  the  Negroes  beftowed  upon  it  the  appellation  of  Joliba,  or  the  Great 
Waters.    Something,  however,  of  doubt  ftill  remained,  particularly  with  regard  to  its 

eaftera 


33»  Mr.  Parkas  Travels  in  the  unexplored  Tarts S)f  Africa. 

eaftern  direction,  which  was  not  received  by  geographers  without  difficulty  and  hefitatiofl. 
Mr.  Park's  teftimony  is  decifive,  not  only  that  the  two  names  denote  the  fame  dream,  but 
tlfothat  it  flows  from  weit  toeaft,  which  he  afcertaincd  by  a  perilous  ambulation  of  fome 
hundred  miles  along  its  bank.  All  quedion  refpefting  the  fource,  the  exillence,  and  the 
diredion  of  this  g'reat  river  is  therefore  obviated,  but  its  termination  ftill  remains  unknown. 

The  city  of  Sego,  at  which  Mr.  Park  now  arrived,  confifts  of  four  divifions  or  quarters, 
two  on  each  fide  of  the  water.  The  houfes  are  built  of  clay  with  flat  roofs  :  fome  of  them 
have  two  (lories,  and  many  are  white-waflied.  Moorifh  Mofques  are  feen  in  every  quarter. 
Thefe  objefts,  with  the  numerous  boats  on  the  river,  a  crowded  population,  and  the  culti- 
Tated  date  of  the  furrounding  country,  formed  altogether  a  profpeft  of  civilization  and 
magnificence,  which  our  traveller  little  expeded  to  find  in  the  bofom  of  Africa.  From 
the  beft  enquiries  he  could  make,  he  had  reafon  to  believe  that  Sego  contained  thirty 
thoufand  inhabitants. 

The  boats  on  the  Niger  are  of  a  fingular  conftruflion,  each  being  formed  of  the  trunk 
of  two  large  trees,  hollowed  out  and  joined  together  endways,  the  jundion  being  exa£lly 
acrofs  the  middle  of  the  boat.  They  are,  therefore,  very  long  and  narrow,  and  have 
neither  decks  nor  mafts.  Mr.  Park  proceeded  to  the  ferry,  in  order  to  crofs  to  the  King's 
refidence,  which  was  on  the  other  fide  ;  but  before  he  could  obtain  a  paflage,  the  King  had 
fent  to  enquire  concerning  the  objeft  of  his  journey.  Mr.  Park  gave  the  beft  anfwer  he  could, 
adding,  that  he  had  been  robbed  of  all  he  pofleflcd,  and  implored  the  King's  bounty  and 
proteclionv  The  meflenger  told  him  to  go  to  a  diftant  village,  which  he  .pointed  out,  and 
wait  for  the  King's  further  orders.  He  found  the  inhabitants  either  afraid  or  unwilling  to 
give  him  lodging  or  entertainment,  and  having  turned  his  horfe  loofe,  he  fought  (belter 
from  a  dorm  of  thunder  and  rain  under  a  tree.  At  length  as  night  approached,  thatkind- 
nefs  and  humanity  inherent  in  the  female  fex,  to  which  Tie  had  often  been  indebted  on 
former  occafions,  came  to  his  relief  on  the  prefent.  A  poor  Negro  woman  returning  from 
the  labours  of  the  field,  obferved  that  he  was  wet,  weary,  and  dejefted  ;  and  taking  up  his 
faddle  and  bridle  told  him  to  follow  her.  She  led  him  to  her  cottage,  lighted  up  a  lamp, 
procured  him  an  excellent  fupper  of  fifh,  and  plenty  of  corn  for  his  horfe  ;  after  which,  (he 
fpread  a  mat  upon  the  floor,  and  faid  he  might  remain  there  for  the  night.  Vox  this  well- 
timed  bounty  our  traveller  prefented  her  with  two  of  the  four  brafs  buttons  which  remain- 
ed on  his  waiftcoat. 

"Mr.  Park  adds  other  particulars  Concerning  his'benefaflrefs,  which  heigliten  the  pi£lure. 
He  relates,  that  the  good  woman  having  performed  .the  rites  of  hofpitality  towards  himfelf, 
called  in  the  female  part  of  the  family,  and  made  ihemfpin  cotton  for  a  greatpart  of  thenight. 
They  lightened  their  labours  by  fongs:  one  of  which  mud  have  beencompofed  extempore, 
for  our  traveller  was  himfelf  the  fubje£l  of  it ;  and  the  air  was,  in  his  opinion,  the  fweeteft 
and  mod  plaintive  he  ever  heard.  The  words,  as  may  be  expected, were  fimple  ;  and  may 
be  literally  tranflated  as  follows-  "  The  winds  roared,  and  the  rain  fell.  The  poor  white 
*'  man  faint  and  weary,  came  and  fat  under  our  tree.  He  has  no  mother  to  bring  liim  milk, 
"no  wife  to  grind  his  corn." — Chorus — "  Let  us  pity  the  white  man,  no  mother  has  he, 
••  &c.  &c."  Simple  as  thefe  words  are,  they  are  natural  and  affecting;  and  contain  a  cu- 
rious allufion  to  the  date  of  manners  in  favage  life,  in  which  the  women  perform  all  the  do- 
jneftic  duties. 

H« 


Mr.  Park's  Travels  in  the  unexplored  Parts  of  Jfrica,  33 1 

He  continued  all  the  next  day  in  the  village  without  receiving  any  orders  from  the  king, 
«nd  found  himfelf  the  obje£l  of  utiiverfal  obfervatlon  and  enquiry.  He  foon  heard  enough 
to  convince  him  that  the  fufpicions  of  the  Moors  and  flave-traders  refiding  in  Sego  were 
Tery  inimical  to  him;  and  that  many  confultations  had  been  held  with  the  king  concerning 
his  reciption  and  difpofal.  On  the  third  day  however  the  meflenger  arrived  with  a  prefent 
of  five  thoufand  kowries,  to  enable  him  to  purchafe  provifions  in  his  journey  from.  Sego, 
from  the  vicinage  of  which  he  was  commanded  to  depart  immediately.  From  various  cir- 
cumftances.itfeemed  probable  that  the  king  would  have  admitted  Mr.  Park  into  his  prefence, 
if  he  could  have  protcfled  him  againft  the  malice  and  fanaticifm  of  the  Moors,  and  if  the 
ftory  of  Mr.  Park  had  been  more  comprehenfible  by  men,  who  could  not  conceive  how  the 
defire  of  extending  knowledge  could  have  induced  him  to  travel  through  fuch  an  extent  of 
country,  vviihout  other  views  of  a  more  objectionable  nature.  From  other  enquiries  it 
was  alfo  rendered  certain,  that  our  traveller  would  have  expofed  himfelf  to  certain  dellruc- 
rion  from  the  iMoors,  if  he  had  ventured  to  proceed  much  further  to  the  weftward  without 
the  proteftion  of  feme  leading  man  among  them,  which  he  had  no  means  of  procuring. 
Notwithftanding  thefe  difcouraging  circumftances,  he  determined  to  endeavour  to  pene- 
trate further  aiong  the  banks  of  the  Niger.  The  firft  town  of  note  at  which  he  arrived 
after  leaving  Sego,  was  called  Kabba.  This  town  is  fituated  in  the  midil  of  a  beautiful 
and  higlily  cultivated  country,  bearing  a  greater  refemblance  to  the  centre  of  England  than 
Mr.  Park  could  have  fuppofed  to  have  been  in  the  middle  of  Africa,  and  the  feafon  was  that 
ef  the  fliea  harveft,  or  gathering  in  the  fruit  which  produces  the  fliea-toulou  or  tree-butter, 
the  great  abundance  of  which  in  this  quarter  was  altonilhing.  The  growth  and  preparaton 
of  this  commodity  feem  to  be  among  the  firft  objeif^s  of  African  indullry,  in  this  and  the 
neighbouring  ftates,  and  it  conftitutes  a  main  article  of  their  inland  commerce.  From 
Kabba,  Mr.  Park  and  his  guide  proceeded  to  Sanfanding,  where  notwithitanding  his  endea- 
Tours  to  avoid  the  notice  of  the  Moors,  he  underwent  their  infults  for  a  confuierable  time. 

Leaving  Hiis  place  early  in  the  morning,  he  proceeded  to  a  town  called  Nyara,  and  thence 
to  Modiboo,  a  delightful  place  on  the  banks  of  the  river,  which  is  here  very  broad  and  en- 
livened with  many  fmall  and  verdant  iflands,  all  of  them  flocked  with  cattle,  and  crowded 
with  villages.  Here  he  was  again  compelled  to  fet  off  abruptly  for.fear  of  the  Moors.  Tiie 
limit  of  his  expedition  to  the  weftward  was  Silla,  a  large  town  on  the  fouthern  fide  of  the 
Niger,  in  1°  24'  Weft  of  Greenwich,  and  latitude  14°  4,8'  North,  where,  from  the  aggregate 
of  unfavourable  circumftances,  it  became  abfoluteiy  neceflary,  for  him  to  return. 

The  town  of  Silla,  whence  Mr.  Park  began  his  journey  homeward,  is  within  two  (hortdays 
journey  of  Jcnne,  which  is  fituated  on  an  ifland  in  the  river.  At  the  diftance  of  two  dayS' 
more,  the  river  empties  itfclf  into  a  confiderable,  lake  called  Dibbie,  (or  the  dark  lake)  con- 
cerning the  extent  of  which,  all  the  information  which  could  be  obtained  was,  that,  in  croft- 
ing it  from  weft  to  eafl-,  the  canoes  lofe  fight  of  land  one  whole  day.  From  this  lake  the 
water  iffues  in  many  different  ftreanis,  which  terminate  in  two  large  branches,  one  whereof 
flows  towards  the  north-eaft,  the  ( ther  to  the  eaft ;  but  they  join  again  at  Kabra,  one  day's 
journey  to  the  fouthward  of  Tombucloo,  and  the  port,  or  Ihippmg  place,  of  that  city.  I  "he 
tradt  of  land  which  the  two  ftreams  encircle,  is  called  Jinbala,  and  is  inhabited  by  negroes  j-, 
and  the  whole  diftance  by  land  from  Jenne  to  Tombudtoo,  is  twelve  days  journey. 

From  Kabra,  at  the  diftance  of  eleven  days  journey  down  the  ilrearti,  the  river  paffes  to  = 

th»^. 


332  Mr.  Park's  Travels  in  the  unexplored  Parts  of  Africa. 

the  fouthwarcl  of  Houfla,  which  is  two  days  journey  diftant  from  the  river ;  and  fo  far  our 
information  feen«  to  be  authentic.  Gf  the  further  progrefs  of  this  great  river  and  its  final 
exit — whether  it  be  the  fame  which  pafTes  by  Kafllna  * — whether  (as  ancient  charts  fecm 
to  indicate)  it  fpreads  into  one  or  more  inland  laites ;  or,  at  an  immenfe  diftance,  intermixes 
with  the  waters  of  the  Egyptian  Nile — thefe  are  qucftions  which  future  dKcovery  can  alone 
refolve.  On  each  of  thefe  points  enquiry  of  the  natives  was  not  negledted,  but  fatisfadlory 
and  certain  information  could  not  be  obtained. 

Such  is  the  intelligence  that  was  coUeded  by  Mr.  Park  concerning  the  courfe  of  the  Niger 
from  its  leaving  Sego,  where  he  firft  difcovered  it.  Of  the  chief  towns  of  Jenne,  Tombuc- 
tco,  and  Houfla,  fituated  on  its  banks,  the  laft  wSs  faid  to  be  the  moft  confiJerable,  and  the 
leaft  of  them  of  far  greater  magnitude  than  Sego.  But  there  is  a  place  between  Jenne 
and  Tombu£too  deferving  notice,  as  containing  a  very  confiderable  pottery :  it  is  called 
Downie  ;  and  the  earthen  ware,  which  Mr.  Park  frequently  met  with,  appeared  to  be  of  ex- 
traordinary good  confiftency,  but  not  glazed.  He  was  told  that  caravans  frequently  arrive 
both  at  Tombudloo  and  Houfla,  from  the  countries  on  the  Mediterranean,  travelling  acrofs 
the  Defert,  by  the  way  of  Fezzan,  with  European  goods  and  other  merchandize.  Ey  one  of 
thefe  the  news  was  conveyed  to  the  centre  of  Africa  of  the  capture,  by  the  French,  of  the 
Mediterranean  convoy,  in  Oitober  1 795.  Mr.  Park  received  this  information  from  a  Moor 
who  had  come  from  Fezzan. 

On  his  return  back,  Mr.  Park  learned  that  the  fovereign  of  the  country  had  given  orders 
to  feize  him,  for  which  reafon  he  avoided  the  town  of  Sego.  His  courfe,  in  afcending  the  river, 
was  to  the  fouth-weft  ;  and  his  fubfiftence,  in  travelling  through  the  territories  of  the  benevo- 
lent Negroes,  was  in  a  great  meafure  afforded  him  by  the  Dooty,  or  chief  man  of  the  towns 
through  which  he  pafTed,  it  being,  highly  to  the  credit  of  the  African  police,  part  of  the 
duty  of  this  officer  to  provide  food  for  the  neceffitous  traveller.  On  many  occafions  he 
■offered  to  pay  for  what  he  received  out  of  the  kowries,  which  had  been  prefented  him  by  the 
'king,  and  his  offer  was  fometimes  accepted  and  fometimes  refufed.  On  other  occafions 
Tie  rewarded  his  hoft  in  a  manner  which,  from  its  fingularlty,  deferves  to  be  noticed. 
Among  the  various  impoflures  pradlifed  by  the  Moors  towards  the  poor  Negroes,  they 
frequently  fell  them  fcraps  of  paper  with  an  Arabic  infcription  (commonly  a  paffage  from 
the  Koran)  which  are  caWeAfaph'us  or  charms.  With  one  of  thefe  about  his  perfon,  the 
fond  poffeffor  conceives  himfelf  invulnerable:  neither  the  lurking  ferpent  nor  the  prowling 
•tiger  is  any  longer  the  obje6l  of  his  dread. 

In  the  circumftances  to  which  Mr.  Park  was  reduced,  he  had  the  good  fortune  to  difcover 
that  the  negro  natives  afcribed  to  him  the  power  of  granting  faphies  of  more  than  Arabic 
virtue.  ^'  If  a  Moor's  faphie  is  good  (fays  the  Dooty  of  .^anfanJing),  a  white  man's  mull 
needs  be  better ;"  and  Park,  at  his  requeft,  gave  him  one  poffeflcd  of  .all  the  virtues  he 
could  concentrate,  for  it  contained  the  Lord's  Prayer.  The  pen  with  which  it  was 
written,  was  made  of  reed  ;  a  little  charcoal  and-gum-water  made  very  tolerable  ink,  and 
a  thin  board  anfwcred  the  purpofe  of  paper.  In  his  journey  we  tward,  this  merchandize 
turned  to  extraordinary  good  account ;  and  it  is  furely  neediefs  (fays  Mr.  Edwards)  foi^ 
Mr^  Park  to  frame  any  apology  fot  having  availed  himfelf  of  fuch  a  refource  in  his  fituation. 

*  Erroneoufly  fpclt  in  the  former  memoirs,  Caflina. 
[Ti  he  continued.'] 


yytt  (Tr  c^m'~eiJ^?ia  '  i^yn./:e,cua€?tc^_J^ 


rhi2ajJourTudyol.Un.Sin.faajlffp.334- 


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JOURNAL 


OF 

NATURAL   PHILOSOPHY,   CHEMISTRY, 

AND 

THE    ARTS. 


NOVEMBER     1  7  9  8. 


ARTICLE   L 

An  Account  of  three  different  Kinds  of  Timber-Trees,  ivhich  are  likely  to  prove  a  great  Ac- 
quifition  to  this  Kingdom,  both  in  point  of  Profit  and  as  Trees  for  Ornament  and  Shade, 

.  By  Charles  White,  Efq.  F.R.S.* 


I 


N  making  a  collection  of  fuch  hardy  trees  and  flirubs  as  would  grow  and  even  flourifli 
in  the  open  air,  at  Sale,'  in  the  county  of  Chefter,  I  foon  obferved  that  there  were  three 
foreft  trees,  of  different  genera,  which  grew  much  farter  than  the  others  in  the  fame  foil 
and  fituation,  viz.  the  Black  American  Birch  with  broad  leaves,  the  AtheniaQ  Poplar,  and 
the  Iron  Oak  with  prickly  cups.  r 

The  Broad  leaved  American  Black  Birch,  Betula  nigra  hmn.  Spec.  Plant.  1394,  is  de- 
fcribed  by  Mr.  Alton  in  his  Hortus  Kewenfis  :  B.  foliis  rhombeo-ovatis,  duplicato-ferratis^ 
acutis,  jubtus  puhefcentibus,  baft  iiitegris ;  flrobilorum  fquamis  villofis ;  laciniis  linearibus, 
aqualibus.  It  is  a  native  of  Virginia  and  Canada,  and  was  firft  introduced  into  England 
(where  it  grows  in  the  greateft  luxuriancy,-and  perfefts  its  feeds)  by  Peter  Collinfon,  Efq. 
in  the  year  1736.  There  is  no  doubt,  therefore,  that  it  will  foon  bec6me  very  plentiful 
and  cheap.  It  is  very  defirable  in  pleafure-grounds,  as  it  is  the  firft  foreft  tree  in  the 
fpring  which  prefents  us  with  its  leaves  ;  thefe  are  of  a  light  and  lively  green.  Its  bark, 
which  is  white,  makes  at  all  times  a  beautiful  variety  when  intermixed  with  other  trees. 
It  is  faid  to  be  the  moft  ufeful  timber  tree  in  North  America  for  building  both  of  houfes 
and  boats,  and  will  grow  faft  in  any  foil  or  fituation,  whether  wet  or  dry. 

?  Manchefter  Memoirs,  yqJ.  v  pan  i. 
Vol.  II.— Nov.  1798.  Xx  Miller, 


/*■■ 


334  Account  of  three  Timber-Trees  tvhkh 

Miller,  fpeaking  of  trees  of  this  defcription,  fays  "  that  they  may  be  propagated  by 
feeds,  in  the  fame  manner  as  the  common  birch-tree,  and  are  equally  hardy.  Some  of  the 
trees  now  begin  to  produce  their  catkins  in  England,  fo  that  we  may  hope  to  have  plenty 
of  their  feeds  of  our  own  growth,  for  at  prefent  we  are  fupplied  with  them  from  America. 
As  thefe  grow  more  vigaroufly_; than,  the  cptumorv  fort,  and  thrive  on  the  moll  barren- 
ground,  they  may  be  cultivated  to  great  advantage  in  England  ;  for  their  wood  is  much 
efteemed  in  Canada,  where  the  trees  grow  to  ^  large  fize  :  and  they  are  by  no  means  an 
unfightly  tree  in  parks  ;  for  their  flems  are  ftraight,  the  bark  fmooth,  and  their  leaves  arc 
much  larger  thgn.thofe  of  the,  common  birch  ;  fo  may  be  planted  in  fuch  places  where  few 
ether  trees  will  thrive." 

Mr.  Hanburyfays  :  "  The  black  Virginian  birch,  being  of  foreign  growth.  Is  propagated 
for  wildernefs  and  ornamental  plantations  j  but  as  it  begins  now  to  become  pretty  com- 
mon, it  is  to  be  hoped  it  will  foon  make  a  figure  among  our  foreft  trees,  it  being  equally 
hardy  with  our  common  birch,  and  vi'ill  arrive  at  a  much  greater  magnitude.  This  fpecies 
will  grow  to  be  upwards  of  fixty  feet  in  height.  The  branches  are  fpotted,  and  more 
fparingly  fet  on  the  trees  than  the  common  forts.  The  leaves  are  broader,  grow  on  long 
footftalks,  and  add  a  dignity  to  thp,  appearance  of  the  tree  ;  and  as  it  is  naturally  of  up- 
jight  and  fwift  growth,  and  arrives  at  fo  great  a  magnitude  in  few  years,  prudence  will 
diredl  us  to  let  it  have  a  (hare  among  our  foreft  trees,  to  plant  them  for  ftandards  in  open 
places,  as  well  as  to  let  them  join  with  other  trees  of  their  own  growth,  in  plantations 
more  immediately  defigned  for  relaxation  and  pleafure."  I  planted  one  of  thefe  trees 
nineteen  years  ago,  and  it  is  now  forty-five  feet  fix  inches  in  height,  and  three  feet  feven- 
inches  in  the  girth. 

The  Athenian  Poplar  Tree,  Populus  (Gra^a)  foli'is  cordaiis,  glahris,  hafi  glandnhfis^  rumti 
crenaih  ;  petioUs  comprejfts ,-  rmnis  iereiibus.  The  Athenian  poplar  is  a  native  of  tlie  iilands 
of  the  Archipelago,  and  was  firft  cultivated  in  England  by  Hugh  duke  of  Northumberland,- 
in  the  year  1779-  Perhaps  there  is  no  deciduous  tree  fo  beautiful,  or  fo  proper  for  plea- 
fure-grounds  intended  for  ornament  and  {hade,  as  this  poplar;  having  a  fine  upright 
ftem ;  the  branches  well  difpofed ;  the  bark  fmooth,  and  of  a  filvery  hue,  refembling 
fatin-wood.  The  leaves,  which  are  of  a  light  green,  are  produced  very  early  in  the 
fpring,  and  are  retained  on  the  tree  longer  than  on  any  deciduous  tree  in  this  country, , 
not  falling  off  till  late  in  the  autumn  :  they  are  never  blighted  nor  infefted  with  infedls,. 
n,or  does  it  lofe  a  leaf  during  the  whole. fummer.  Though  the  poplar  is  generally  termed 
an  aquatic,  this  will  grow  in  any  foil  or  fituation;  and  is  of  quicker  growth  in  dry  up- 
land than  any  tree  we  are  acquainted  with  in  this  climate,  though  not  quite  of  fuch  quick 
growth  as  the  Huntingdonlhire  willow  in  rich  moift  meadow  land.  In  fuch  a  fituation,  I 
have  fallen  a  Huntingdonfhire  willow*,  from  which  I  made  a  ftaircafe  when  it  was  only 
of  nineteen  years  growth,  from  a  cutting.  The  Atheeian  poplar  is  propagated  with  the  . 
greateft  advantage  by  fuckers  and  layers ;  but  it  Is  with  great  difficulty  raifed  from  cuttings 
or  truncheons.  The  common  way  of  raifing  them,  amonglt  the  nurferymeri,  is,  by 
engrafting  them  on  fome  other  poplar  :  but  the  trees  thus  raifed  are  of  little  value,  being 
very  flow  in  their  growth  }  and  it  is  owing  to  this  circumftance,  perhaps,  that  tjieir  real 

•  I  cannot  find  that  this  fpecies  of  willow  has  been  defcribed  by  any  botanical  writer  j  but  it  is  we)l  known 
among  the  nurferyraen  by  this  name. 

wortJi 


art  like! J  to  prove  a  ^Yfat  'fiatkm!  JJvantage.  333 

tponh  has  not  before  been  dlfcovered.  About  twelve  years  ago  I  purchafed  two  plants  of 
this  poplar,  from  two  different  nurferymen  in  London,  at  one  guinea  each  ;  one  of  them 
was  grafted  upon  a  dlfl'crent  kind  of  poplar,  the  other  was  upon  its  o\yn  foots.  I  placed 
them  near  together,  in  a  dry  fituation,  in  a  light  foil,  underneath  which  was  a  ftratum 
of  gravel.  The  grafted  one  made  very  little  jprogrcfs ;  I  therefore  converted  it  into  a 
•ftool,  and  raifcd  fevcral  plants  from  it.  The  other,  which  is  upon  its  own  roots,  has 
•  made  a  rapid  progrefs,  being  at  lead  fifty-one  feet  high,  and  two  feet  nine  inches  in  the 
girth.  It  produces  annually  a  great  number  of  fuckers,  with  which  I  have  fupplied  many 
of  my  friends*. 

The  third  is  The  Iroti,  Waitifcot,  or  Turkey  Oak,  fo  called  by  Mr.  Luccomb.  I  have 
long  been  in  doubt  what  fpecies  of  oak  this  really  was ;  but  one  of  mine  having  borne 
fome  acorns  this  year,  has  afcertained  it  to  be  a  variety  of  the  querau  cerrii ;  and  it  ap- 
pears to  me  to  be  either  a  noiidejcript,  or  what  Mr.  Aiton,  in  his  Hortus  Kewenfis,  calls 
frondoja :  foliis  ovato-obhngis,  leviter  finuatis,  planiufculis :  commonly,  Turkey  oak  tree. 
It  is  what  Mr.  Luccomb  generally  grafts  his  Luccomb  oaks  upon  -,  and  the  plants  certainly 
grow  falter  when  grafted  upon  this  'oak  than  upon  any  other.  About  twenty  years  ago, 
in  making  a  colle£lion  of  oaks,  I  received  feveral  from  A4r.  Luccomb^  both  of  the  iron 
and  the  Luccomb  oak ;  but  I  foon  ■  found  that  the  iron  oak  overgrew  all  the  others,  and 
*ras  equally  ornamental  as  the  Englilh  oak.  From  a  branch  which  I  have  fawed  off,  the 
wood  appears  to  Be.as  hard  and  as  ponderous  as  the  Eiiglifli  oak. 

The  following  is  an  account  of  the  fize  and  age  of  fome  Iron,  Luccomb,  and  Englifli 
Oaks,  growing  in  my  collection  at  Sale  : 


Height.                  Girth. 
Feet.     Inches.            Feet.     Inches. 

36  0     3           3 

37  0               30 

32        2    2 

28        0    2 

S 
6 

39        0    2 

54        0     3 

10 

4 

An  iron  oak,  20  yeari  old            —  . 

Another,  of  the  fame  age             —  — — — 
A  Luccomb  oak,  of  the  fame  age,  grafted  on  an 

Englifh  oak  —  

An  Englifli  oak,  of  the  fame  age  — — 

Another,  40  years  old               —  — .^_ 

Another,  56  years  old  —  • 

The  following  is  a  Copy  of  a  Letter  from  Mr.  Luccomb  to  Mr.  Babington,  dated  New- 
bridge, Exeter,  September  17,  1795  : 

«'  All  I  can  fay  of  them  (the  iron  oaks)  is,  that  my  father  had  a  few  of  them  as  a  pre- 
fent  from  William  Ball,  Efq.  of  Manhead-houfe  (now  lord  Lefburne's,  near  Chudleigh, 
Devonfliire),  about  fifty  years  fitice,  by  the  name  of  the  iron  or  wainfcot  oak,  which  ,Mr. 
Ball  received  from  Turkey  by  one  of  his  own  fliips  trading  there.  They  are  the  fame 
fort  which  you  have  noticed  at  Hillerfdon,  as  my  father  fold  fome  of  them  to  Mr.  Creroy 
about  forty  years  fince.  They  have,  as  you  obferve,  a  very  jagged  leaf,  and  the  cup  of 
the  acorn  is  rough  Hke  a  bur.     They  are  hot  evergreen." 

■^  There  is  another  psplar  of  very  fwift  growth,  which  rtiakes  a  very  handfome  tree,  and  will  flouriih  in 
any  fituatioi\  or  foil.  It  is  tl^e  Popitlns  cordifolia  canadaifis,  or  Berry-bearing  Poplar,  as  it  is  commonly 
cai!e<i,    This  tree  will  grow  freely  from  cuttings. 

X  X  2  Th« 


■  •^^ 

336  Account  t>f  three  Tmief'Trees  luhich 

The  following  is  a  Letter  I  received  from  my  worthy  friend  the  Rev.  Thomas  Gifborne, 
author  of  feveral  ufeful  publications  : 
«  Dear  Sir, 

"  Yoxall  Lodge,  Oft.  10,  1795. 
**  I  have  this  evening  received  a  letter  from  m^  brother-in-law,  Mr.  Babington,  re- 
fpe(Sling  the  meafurements  of  the  iron  oaks  at  Hillerfdon,  near  CuUompton,  where  he  now 
is :  I  fubjoin  what  he  fays  on  the  fubjeft,  and  have  pleafure  in  finding  the  refult  fo  ho- 
nourable to  the  tree  which  you  recommend. 

"  I  am,  Sir,  &c. 

"  Thomas  Gisborne.    « 

«* To-day  I  have  meafured  fome  of  the  oaks  about  three  feet  and  a  half  from  the 

ground ;  and  give  you  the  refult,  which  I  thought  would  be  fair  and  fatisfailory,  in  tlie 
following  way :— — 

**  No.  of  Englifli  oaks.  Circumference. 

Feet.     Inches. 

8  " 31        I 

9  . 30        I 

9  32        8 

16  a6)  93      10 

;  Average  circumference  3        7^- 

**  No,  of  iron  oaks.  Circumference. 

Feet.     Inches. 

6  31        6 

6  •  — 32      10 

6  31        9 


18  18)  96 


Average  circumference  5         4 

**  As  circles  are  as  the  fquares  of  their  circumferences,  pieces  of  the  buts,  at  this 
height,  a  foot  long,  would  be  to  each  other  331877:4096.  Now,  fuppofing  the  iron 
oaks  to  carry  their  buts  as  much  higher  than  the  others  as  their  fubllance  below  would 
lead  us  to  expe£l:  (and  they  feem,  in  fa£l,  to  do  this  or  more),  there  muft  be  four  or  five 
times  as  much  wood  in  them  as  there  is  in  the  Englifli  oaks.  An  old  labourer  here  in- 
forms me,  that  all  were  planted  at  the  fame  time,  between  forty  and  fifty  years  fince. 
They  ftand  in  rows,  ten  feet  afunder,  and  the  trees  are  twenty  feet  from  each  other  in 
each  row.  I  meafured  fuch  trees  as  firft  prefented  themfelves,  with'  the  exception  of  one 
or  two  which  feemed  unhealthy.  They  are  on  a  fteep  bank  and  a  gravelly  foil.  The 
trunks  of  the  iron  oaks  are  covered  with  a  lighter  mofs,  on  the  whole,  than  fixes  kfelf  on 
the  EngKlh  oak ;  but  make  a  fine  appearance.  I  meafured  many  outfide  trees,  and  oh- 
ferved  that  the  iron  oak  feemed  to  have  as  great  a  fuperiority  over  the  other,  in  this  fitua- 
tion,  as  it  has  when  furrounded  by  neighbours.  As  to  the  height,  the  iron  oaks  very  ge- 
nerally out-top  the  others,  and  are  the  mailer  trees  j  but  you  know  that  in  a  plantation^ 
Header  tree  will  pften  be  nearly  as  tall  as  its  fturdy  neighbour.  \ 


are  liitly  to  prove  a  greet  .national  Advantage,  I37 

*'  P.  S.  On  looking  over  the  oaks  again,  I.  think  the  iron  oaks  carry  up  the  thicknefs  of 
their  buts  a  good  deal  better,  cateris  paribus,  than  the  others  ;  and  therefore  they  have  five 
or  fix  times  the  quantity  of  wood  in  them. 

"  There  are  but  two  beeches,  and  they  arc  both  outfide  trees,  and  therefore  larger  than 
they  othcrwife  would  be.  The  circumference  of  the  two  was  12  feet  4  inches;  average, 
6  feet  2  inches. 

"  Spanifh  chefnuts,  No.  Circumference. 

Feet.     Inches. 

6  31        3 

8  u-  34        3 

4  24        3 

18  •  ■■■..  18)  89        9 


Average  circumference  4       1 1 J  nearly." 

N.  B.  Mr.  Bablngton  fays,  "  that  there  are  gates  and  pales  on  the  premifes  at  Hillerfdon, 
which  have  been  made  of  the  iron  oak  ;  and  that,  as  far  as  he  can  judge,  the  wood  appears 
as  hard  and  as  tough  as  that  of  the  common  oak." 

It  has  always  been  confidered,  that  when  men  have  planted  oak,  they  have  not  planted 
for  themfelves,  or  for  their  children,  but  for  dillant  poflerity ;  and  even  they  could  never 
be  repaid  where  land  bore  any  annual  value  :  and  to  the  planter  himfelf  little  pleafure  could 
arife  from  trees  of  fuch  very  flow  growth.  But  the  fame  perfon  who  plants  the  iron  oak 
may  poffibly  live  to  reap  fome  little  profit  as  well  as  pleafure ;  and  it  is  not  at  all  unrea- 
fonable  to  fuppofe  his  immediate  fucceffor  may  fee  it  arrive  to  fome  degree  of  perfecflion. 
From  what  I  have  feen  of  the  wood  of  this  oak,  and  from  the  account  given  by  Mr.  Ba- 
bington  of  the  gates  and  pales  made  with  it,  there  is  great  reafon  to  fuppofe  it  will  be 
equally  ufeful  as  the  Englifh  oak  for  any  purpofe  whatever. 

The  general  decreafe  of  timber  in  this  ifland,  the  many  wafte  lands  unemployed,  and  the 
bill  now  propofed  to  be  brought  into  Parliament  by  that  great  friend  to  agriculture  Sir 
John  Sinclair,  will  be  my  apology  for  troubling  the  Society  with  this  paper  ;  for  the  planter 
ought  certainly  to  be  furniflied  with  every  advantage,  and  every  poffible  inducement  (hould 
be  held  out  to  him  for  promoting  fo  ufeful  and  fo  national  a  work. 

Explanation  of  Plate  XV.  fig.  1. 

A.a.  a.a.  Leaf,  acorn,  and  prickly  cup  of  the  Iron,  Wainfcot,  or  Turkey  Oak. 

B.B.b.b.  Leaf,  acorn,  and  prickly  cup  of  thri  ^urcus  Cerris  of  LinnteuSy  fol.  oUonght 
hrato-pinnatifidis  ;  laciniis  tranfverft!,  acutis,  fubtus  fuhtomentojis  ;  calyce  hifpido  ;  glande  mi- 
nore.     Small-acorned  Spanifli  Oak  with  prickly  cups. 


n. 

Ahjlra^  of  a  Memoir  of  M.  PsOUSTon  the  Tanning  Principle*.      By  Citizen  DESCQTILt. 

x\.  SOLU  riON  of  muriate  of  tin,  at  any  degree  of  oxydation  whatever,  being  poured 
into  a  deco6lion  of  nut-gall,  forms  an  abundant  yellowifh  precipitate.    After  having  di- 

•  AnnaUs  de  Chimic,  jutv,  iiy 

luted 


338  ExperlmtKii  en  the  Tanning  Prtnc'tpk  and  Add  of  Galls. 

luted  tills  mixture  with  a  quantity  of  water  fuflicient  to  feparate  the  lad  portions  of  preci- 
pitate which  the  acids  may  hold  in  folution,  it  is  filtered,  and  the  liquor  contains  the  acids 
of  galls,  muriatic  acid,  and  muriate  of  tin.  The  precipitate  is  a  combination  of  the  tanning 
principle,  and  the  oxyde  of  tin.  It  cannot  contain  the  gallic  acid,  becaufe  this  acid  is  not 
precipitated  by  tin.  The  folutions  of  lead,  on  the  contrary,  precipitate  the  gallic  acid,  as 
•well  as  the  tanning  principle ;  and  on  this  account  it  was  that  Scheele  could  not  feparate 
the  acid  of  galls  from  the  principle  of  aftringency. 

In  order  to  obtain  the  acid  of  galls,  the  tin  mud  firft  be  feparated  by  fulphurated  hydro- 
genous gas.  The  fulphurated  oxyde  falls  down  in  the  form  of  a  brown  powder.  After 
having  left  the  fluid  expofed  to  the  fun,  with  a  covering  of  paper,  in  order  that  the  excefs 
of  fulphurated  hydrogen  gas  may  be  diflipated  or  entirely  decompofed,  it  is  to  be  filtered, 
and  then  evaporated,  in  a  vefTel  of  filver,  to  the  reqiiifite  point  for  the  crydallization  of  the 
gallic  acid  by  cooling.  The  cryftals  being  then  thrown  on  a  filter  muft  be  wafhed  with  a 
fmall  quantity  of  cold  water.  The  remaining  fluid  is  to  be  treated  by  evaporation,  and 
cooling  in  the  fame  manner,  in  order  to  deprive  it  as  much  as  poffible  of  gallic  acid.  At 
the  end  of  the  operation,  it  is  neceflary  to  ufe  capfules  of  glafs,  becaufe  the  muriatic  acid 
becomes  concentrated.  The  earths  which  fome  chemifts  have  pretended  to  exift  in  the 
decodtion  of  nut-galls  ought  to  be  found  in  this  refidue.  Mr.  Proud;  met  with  none ;  but 
he  propofes  to  examine  the  refidue  with  more  particular  attention  to  this  point. 

To  feparate  the  tanning  principle  from  its  combination  with  the  oxyde  of  tin,  tliis  lad 
powder  is  difFufed  in  a  quantity  of  water,  through  which  a  current  of  fulphurated  hydro- 
genous gas  is  pafled.  The  fulphurated  oxyde  falls  down,  and  the  pure  tanning  principle  at 
the  fame  time  becomes  diflblved  in  the  water.  After  filtration,  the  folution  Is  evaporated  in 
a  filver  bafon,  in  which  it  acquires  the  deep  colour  of  a  decoftion  of  nut-galls,  and  its  pe- 
culiar fmell,  which  is  one  of  the  diftindive  charaQers  of  the  aflringent  principle.  Its  tafte 
is  exceedingly  acerb,  and  rather  bitter,  without  being  difagreeable.  It  lathers  like  foap- 
water,  without  feeling  unftuous  to  the  touch.  It  becomes  turbid  by  cooling,  and  lets  fall 
a  light  brown  powder,  which  is  diflblved  again  by  heat.  It  refembles  the  laft  decodtions  of 
nut-galls,  which  do  not  become  mouldy,  and  are  thought  by  Mr.  Prouft  to  contain  the 
tanning  principle  nearly  in  a  ftate  of  purity. 

The  fubflance  which  remains  after  its  evaporation  is  dry,  brown,  friable,  breaks  with  a 
vitreous  fra£lure,  like  aloes,  and  does  not  attract  the  humidity  of  the  air.  Its  tafte  is 
very  rough  and  harfh  :  it  is  totally  foluble  in  hot  water,  and  flill  more  readily  in  alcohol. 

All  the  acids  precipitate  the  tanning  principle  from  its  aqueous  folution,  by  uniting  with 
it.  As  this  fad  belongs  to  the  analyfis  of  galls,  which  Mr.  Prouft  has  made  by  means  of 
the  fulphuric  and  muriatic  acids,  he  promifes  to  treat  of  it  again  in  the  fecond  part  of  his 
work. 

The  aqueous  folution  of  the  tanning  principle,  poured  into  a  folution  of  glue,  imme- 
diately converts  it  into  a  magma,  which  pofl"efles  the  elaftic  properties  of  the  gluten  of 
wheat.  This  fubflance,  when  left  to  dry,  contrafls  in  its  dimenfions,  and,  when  perfectly 
dry,  has  the  appearance  of  a  brown  mafs,  vitreous  in  its  fradture,  not  capable  of  putre- 
faction, perfedly  infoluble  in  water,  yielding  little  to  alcohol,  and  capable  of  refuming  its 
elaftic  property  by  foftening  it  in  hot  vi'ater.  It  is,  in  a  word,  favs  the  author,  the  com- 
bination dlfcovered  by  Seguin,  the  preferving  principle  of  tanned  leatlier.  It  is  alfo  ob- 
tained with  the  folution  of  the  nut-gall. 

Albuminous 


Expertmenfs  in  th  Tanning  Principle  nnd  Jcid  of  Galh.  339 

Afbumlnous  liquors  are  precipitated  by  the  tanning  folmion,  but  the  refult  is  not  a  mag- 
ma fulccptiblc  of  the  fame  concentration. 

The  green  fulphate  of  iron  is  no  more  altered  by  the  tanning  principle  than  by  the  acid 
of  galls  *. 

7  he  red  fulphate,  on  the  contrary,  is  precipitated  in  a  fomewhat  tarnifhed  blue  depofi- 
tion,  which  is  abundant,  coarfe,  and  of  a  black  colour  when  dry.  If  the  precipitate  which 
this  fulphate  aflbrds  with  the  gallic  acid  be  compared  with  this,  it  will  be  feen  that  they 
greatly  differ.  The  former  is  of  an  extreme  fubtlety,  and  remains  long  fufpended  in 
water :  it  is  perfedlly  black,  &c. 

The  gallate  of  iron  is  foluble  in  acids ;  the  tannate  of  iron  is  decompofed  by  thofe  falts. 
It  abandons  its  iron,  and  the  tanning  part  falls  down. 

If  th*;  red  fulphate  be  poured,  rather  in  excefs,  into  a  folution  of  the  tanning  principle,  the 
difengaged  fulphuric  acid  re-diflblves  the  precipitate,  and  affords  a  black  fluid  in  its  greatefl 
jntenfity,  which  is  blue  when  much  diluted.  To  feparate  the  precipitate,  without  depriving 
it  of  the  tanning  principle.  It  is  neceffary  that  the  excefs  of  acid  in  the  fluid  (hould  be  gra- 
dually faturated  by  pot-afh.  With  a  little  attention,  the  operator  may  fucceed  in  rendering 
the  liquor  colourlefs,  without  affecting  the  fuperabundant  portion  of  fulphate;  or  other- 
wife.  If  a  fmall  portion  of  oxyde  of  Iron  has  been  thrown  down  along  with  the  black  pre- 
cipitate, which  may  be  known  by  the  rult  which  is  formed  upon  the  filter,  a  few  drops  of 
acid  will  re  diffolve  it. 

But  it  is  a  remarkable  fa£l,  that  all  the  red  fulphate  remaining  in  the  fluid  is  brought 
back  to  the  ilate  of  green  fulphate.  The  quantity  of  oxygen  which  conftitutes  the  diffe- 
rence between  the  one  and  the  other,  is  feized  by  a  portion  of  the  tanning  principle. 
The  latter  thus  oxyded,  and  by  that  means  rendered  incapable  of  precipitating  the  red  ful- 
phate, remains  in  folution.  This  oxydation  of  the  tanning  principle  is  direftly  and  eafily 
obtained  by  the  oxygenated  muriatic  acid.  The  folution  of  the  tanning  principle,  inflead  of 
becoming  clearer,  acquiies  a  deeper  colour,  and  lofes  all  its  peculiar  characters  in  its 
tranfition  to  a  new  Itate,  which  Mr.  Proud  has  not  yet  examinedf. 

The  gallic  acid  undergoes  .the  fame  alterations  by  the  oxygenated  muriatic  acid,  and,  like 
the  folution  of  the  tanning  matter,  becomes  incapable  of  precipitating  the  red  fulphate. 
This  is  the  effeft  which  age  produces  upon  ink.  The  gallic  acid  is  deftroyed,  the  red  oxyde 
remains,  and  may  eafily  be.  rendered  blue  by  the  method  of  Blagden. 

As  the  aftringent  juices  cannot  afford  indeflru£lible  inks,  we  mud  therefore  return  to  the 
method  of  the  antients,  who  ufed  coal  for  this  purpofe.  Perhaps,  fays  Mr.  Proufl,  there  is 
no  fubftance  fo  proper  as  Spanifti  chalk.  This  Hone,  which  is  neither  bituminous  nor  am- 
pelite,  is  found  with  the  amianthus,  and  is  compofed  of  alumine  with  fix  or  feven  per  cent, 
of  pure  charcoal. 

The  fame  phenomenon  of  the  oxydation  of  the  blackening  principle  at  the  expence  of  the 
red  fulphate.  Is  alfo  obferved  in  black  dyes  made  with  fumac  and  this  metallic  fait.  Mr. 
Proud  had  occafion  to  obferve  it  in  a  oath  of  this  kind,  which  no  longer  added  to  the  black  co- 
lour of  the  piece  goods.  The  liquor  was  greenifli;  the  red  fulphate,  or  the  oxygenated  muriatic 

•  On  tljis  fubjedl,  fee  the  interefting  paper  of  this  author,  in  our  Journal^  I.  453.  N, 
t  See  the  obfervations  of  Seguin,  Philof.  Journal,  I.  475. 

acid^ 


340    .  jBIack  D^e.-^DouhU  EleBhf  Aiiraliiotis. 

acid,  Immediately  formed  black.  Hence  he  concluded  that  the  gallic  acid,  or  the  aftringent 
principle  and  the  green  fulphate,  exifled  together  in  the  bath.  The  red  fulphate  which  was 
poured  in,  combined  with  the  vegetable  principle  ;  the  oxygenated  muriatic  acid,  by  con- 
verting the  green  fulphate  into  red,  gave  it  the  facility  of  combining  and  affording  black 
with  the  fame  principle. 

From  thefe  fafts  it  follows,  that,  in  the  procefs  of  dyeing  black,  a  portion  of  the  blackening 
principle,  whether  it  be  the  tanning  matter  or  the  acid  of  galls,  is  deftroyed  by  oxydation  ; 
that  a  certain  period  arrives  at  which  the  bath  canno  longer  afford  the  black  dye,  unlefs,  by 
expofure  to  the  air,  the  iron  can  refume  the  quantity  of  oxygen  neceflary  to  bring  It  to  the 
ftate  of  red  oxyde  ;  and  lafliy,  that  dyers  would  confiderably  accelerate  their  work  by  ufing 
the  red  fulphate.  It  would  only  be  neceflary  in.  that  cafe  to  provide  againft  the  excefs  of 
fulphuric  acid,  which  always  is  found  in  the  fulphate  of  iron  when  it  paffes  from  green  to 
red.  "With  regard  to  the  ufe  of  logwood,  verdigris,  &c.  Mr.  Prouft  is  convinced  th^ 
thefe  fubftances  are  not  necefTary,  and  that  the  mod  beautiful  blacks  may  be  obtained  by 
afiringents  alone  with  iron. 


III. 

Notice  of  a  Memoir  of  Citizen  GuTTON,  upon  the  Tables  of  the  Compofttion  of  Salts,  and  the 
Means  of  verifying  the  Proportions  indicated  by  thofe  Tables*.  '    - 

A  H  E  little  agreement  between  the  tables  of  Bergman,  Wenzel,  and  Klrwan  fliews  all 
the  difHculty  of  determining  with  exadlncfs  the  proportions  of  the  component  parts  of 
falts.  A  method  of  verifying  fuch  tables  would  therefore  be  ufeful  to  the  progrefs  of  fclence. 
.The  following  appears  fo  fimple  and  appropriate,  that  it  is  aftonifliing  it  has  not  yet  been 
attempted.  It  confifts  in  a  comparifon  of  the  rcfults  of  experiment  and  computation,  with 
regard  to  the  agreement  of  the  very  perceptible  effect  arifing  from  the  excefs  or  deficiency 
of  one  of  the  fubftances  after  mutual  decompofition. 
For  example,  according  to  Bergman  : 

Sulphate  of  Barytes  contains   Acid      13.' 

Barytes  84. 
Sulphate  of  Soda  contains        Acid       28. 

Soda       1(5. 
Muriate  of  Barytes  contains    Acid      23,57 

Barytes  76,43 
Muriate  of  Soda  contains  Acid       52. 

Soda  42. 
Negleding  the  water,  which,  though  of  fome  confequence  in  the  efTefl,  Is  of  none.In  the 
rcfult  J  we  fee  that,  in  the  cafe  of  an  exchange  of  bafes  between  two  falts,  the  refult  of  the 
mixture  mufl  either  be  neutral,  or  poflefs  an  excefs  of  acid,  or  an  excefs  of  the  bafe  ;  and 
that,  by  rendering  the  decompofition  of  one  of  the  falts  complete,  we  ought  to  obtain  the 
fame  refult  from  calculation  as  that  which  lliall  be  afforded  by  experiment. 

*  Head  to  the  National  Inftitute  of  France,  the  16th  Praid»l,  in  the  year  V.    This  notice  is  tranflatcd  from 
the  Annaks  de  Clumie,  xxr.  292. 

Now, 


Remarkable  Effecl  of  the  Double  Ele^ive  AUraElions,  341 

Now,  if  by  the  fulphate  of  foda  \<'e  decompofe  a  quantity  of  muriate  of  barytes  contain- 
ing, according  to  the  above  table,  25,906  of  muriatic  acid,  there  ought  to  remain  difen- 
gaged,  or  in  excefs,  16,710  ; — nevertheiefs  the  mixture  remains  neuter. 

The  fluid  remains  alfo  neuter,  if  we  ceafe  to  add  the  folution  of  fulphate  of  foda  when  the 
precipitate  no  longer  falls  down.  The  computation  Ihews,  that  in  a  hundred  parts  of  the 
mixture  of  thefe  two  falts,  in  which  the  muriatic  acid  would  be  reprefented  by  ao,  there 
ought  to  remain  1 2  unfaturated,  or  in  excefs. 

Let  us  apply  the  fame  method  of  verification  to  the  proportions  determined  by  Kirwan  in 
the  new  tables  in  the  fecond  edition  of  his  Differtation. 

It  is  known,  that  an  exchange  of  bafes  takes  place  between  fulphate  of  foda  and  muriate 
of  magnefia.  The  computation  eftabliflied  on  the  proportions  indicated  by  the  tables  fo 
rigoroufly  affumed  from  the  real  acids,  always  {hews  a  notable  excefs  of  acid,  either  muria- 
tic or  fulphuric,  accordingly  as  the  quantity  of  one  or  the  other  of  thefe  falts  is  increafed  in 
the  mixture. 

The  doubts  entertained  by  certain  chemlfts  on  the  refpeftive  decompofition  of  thefe  two 
falts,  have  induced  me  to  apply  the  fame  calculation  to  the  inverfe  operation,  that  is  to  fay, 
by  mixing  the  folutions  of  fulphate  of  magnefia  and  muriate  of  foda  ;  and  in  this  cafe  alfo 
the  refults  do  not  agree. 

Laftly,  the  method  has  been  tried  on  a  cafe  of  affinity,  in  which  the  decompofition  Imme- 
diately fliews  itfclf  by  unequivocal  figns;  that  is  to  fay,  in  the  mixture  of  a  folution  of  ful- 
phate of  potafti  and  nitrate  of  lime. 

According  to  the  lafl;  data  of  Kirwan,  the  proportions  of  the  component  parts  of  thefe  two 
falts,  and  the  two  others  which  ought  to  be  formed,  are  as  follows  : 

Sulphate  of  Potalh  -     {^^^  J^^ 
Sulphate  of  Lime      .     j^cid     loo^ 

Nitrate  of  Potafh      -     {^f^^'H^^ 

f  Acid     100 
ime      34,4 

It  is  eafy  to  form  the  mixture  of  a  quantity  of  fulphate  of  potafli^of  which  the  acid  fhall  be 
reprefented  by  the  number  100,  together  withfomuchof  the  nitrate  of  lime  that  there  fhall  be 
more  than  fufficient  to  caufe  the  whole  of  the  fulphuric  acid  to  pafs  into  a  new  combination. 
It  is  evident  that,  to  effeft  this,  80,6  of  lime  will  be  required,  which  will  therefore  be  difen- 
gaged  from  234,4  of  nitric  acid  ;  a  quantity  which  would  require  for  its  faturation  195,32 
of  potafii.  But  it  finds  only  10,87.  The  quantity  of  nitric  acid  remaining  without  any 
bafe,  or  in  excefs,  mufl;  confequently  be" 64,87. 

Such  is  the  refult  of  calculation  ;  but  experiment  pronounces  otherwife.  The  fluid  di- 
luted or  concentrated,  and  even  carried  to  cryflallization,  did  not  at  any  period  prefent  the 
leaft.  trace  of  difengaged  acid. 

The  author  declares  in  conclufion,  that  his  intention  is  not  to  criticife  experiments  made 

with  no  lefs  care  than  fagacity  ;  but  to  offer  to  chemifts  a  problem  which  is  interefi;ing  in 

many  refpefts,  theoretical,  praftlcal,  and  even  pharmaceutical ;  a  problem  of  which  the 

folution  is  no  longer  to  be  fought  in  the  amendment  of  fuch  errors  as  are  unavoidable  in 

Vol.  II. — Nov.  1798.  Yy  manipu- 


Nitrate  of  Lime       -     <  ^  . 
ILir 


342  P^^gi'ophj !  oryXIniverfal  Writing. 

manipulations  of  great  delicacy  ;  but  which  alfo  leads  u}  to  confukr  the  confequences  of 
the  affinities  in  faline  mixtures  under  a  new  point  of  view,  in  order  to  difcover  the  caufe  of 
a  refult  fo  little  agreeing  with  all  the  obfervations  which  have  yef  been  made  upon  their 
compofition*. 


IV. 

On  Pafigraphy\  or,  the  Art  of  Writing  nvhich  Jball  be  intelligihk  to  all  Nat  ions  f. 

V>*ITIZEN  Memieux  has  promlfed  to  affift  us  with  a  pafigraphy,  or  univerfal  writing, 
by  means  of  twelve  characters  which  may  be  learned  in  twelve  hours.  This  extreme  fim- 
plicity  is  entitled  to  the  utmoft  attention  of  philofophers,  and  feems  to  indicate  a  very  fuperiof 
mind  in  the  author.  We  mud  neverthelcfs  enquire,  what  may  be  the  nature  of  tliefe  cha- 
racters ;  for  their  form  is  of  no  great  confequcnce.  Are  they  alphabetical  ?  Or,  are  they 
a  kind  of  hieroglyphic,  each  exprefling  an  idea,  like  the  charafters  of  the  Chinefe  writing  ? 

If  the  queftion  relate  to  an  alphabet,  the  fecret  is  certainly  not  uncommon  ;  bu:,  if  the 
characters  be  hieroglyphical,  It  will  be  difficult  to  comprehend  how  twelve  primitive  ideas 
and  their  reprefentative  figns  can  be  fufficient  for  every  combination.  In  either  cafe,  there 
is  a  new  language  to  be  learned,  which,  it  is  expefled,  the  various  nations  will  adopt.  A 
Portuguefe  receives  the  information  that  a  certain  character,  a  crofs  for  example,  is  to  be 
made  ufe  of  to  denote  a  fhip;  the  fame  information  is  communicated  to  an  Indian;  and, 
when  thefe  two  men  meet,  If  they  trace  a  crofs  upon  their  tablets,  they  will  both  compre- 
hend that  a  fliip  is  meant, — and  fo  of  the  reft.  Without  proceeding  fo  far  from  the  ordinary 
practice,  I  might  fay  both  to  the  Portuguefe  and  the  Indian,  Write  the  word  navls,and  you 
will  equally  underftand  each  other  ;  or,  in  fliort,  I  might  command  all  the  people  on  the 
face  of  the  earth  to  learn  Latin,  or  any  other  common  language,  and  then  acquaint  them, 
that  this  qualification  would  enable  them  to  underftand  each  other. 

In  this  manner  it  is,  that  all  the  nations  who  have  adopted  the  Arabian  cyphers  caa 
readily  communicate  all  their  ideas  of  numbers  and  their  combinations,  notwithftanding  the 
difference  of  their  languages.  When  a  native  of  France  fees  a  German  write  234,  both 
have  a  perception  of  the  fame  objedt,  and  underftand  each  other  perfeftly,  though  the  one 
in  oral  fpeech  would  ^z.^  dei4x  cents  trente  quatre,  and  the  other  ztu^  hundert  vier  und  dreiftg. 
Let  the  German  continue  to  write  numbers,  and  to  perform  the  moft  complicated  opera- 
tions, the  Frenchman  will  follow  and  comprehend  them  without  difficulty.  The  algebra- 
ifts  of  all  nations  underftand  at  firft  fight  the  procefles  written  by  nations  pofleffing  other 
idioms.  The  fame  thing  happens  with  regard  to  the  figns  of  pharmacy,  the  ancient  chemiftry, 
aftronomy,  and  mufic.    Let  a  number  of  Italians,Englifli, French,  and  Germans,bc  colle£ted 

*  At  the  end  of  this  paper,  the  author  does  juftice,  in  a  notei  to  M.  Richter,  who,  in  his  Neuern  Gcgen- 
ftande  dcr  Chymie,  &c.  makes  the  fame  obfervation,  to  which  he  was  led  by  the  great  difference  between  the 
proportions  indicated  in  the  tables  already  known,  and  thofe  he  had  determined  by  a  new  method,  which  he  calls 
ftachiometrique.     I  hope  to  proc\ire  this  work  foon.     N. 

t  From  the  Sptftateur  du  Nord,  Mai  1798.  The  fignature  V*'*  **•*  is  annexed  to  this  paper.  I  have 
omitted  the  two  firft  paragraphs,  which  form  no  eflential  part  of  the  fubjeft,  and  are  written  in  a  ftyle  of  levity 
which  can  fcarcely  accord  with  the  reft  of  this  excellent  paper. — Reference  to  two  Memoirs  on  the  fame 
fubjeft,  with  a  few  remarks,  is  made  in  our  Journal,  11.  189—191.    N, 

together 


On  the  Hijtory  of  a  Ph'ihjophical  Language,  34iS'^ 

together  in  an  orchellra,  perfectly  unacquainted  with  each  other,  let  the  parts  of  the' 
fame  fymphony  be  diftributed  among  them,  and  they  will,  by  performing  the  mufical  compo- 
fition,  afford  a  convi6lion,  that,  in  fpite  of  the  difference  of  language,  the  mufical  pafigraphy 
reprefents  the  fame  ideas  to  them  all. — But  in  thefe  feveral  cafes  of  arithmetic,  algebra^ 
mufic,  &c.  it  is  evident,  that  nothing  more  has  happened,  than  that  all  the  profeflbrs 
have  been  previoufly  induced  to  learn  one  common  language.  This  confideration  caufes 
the  miracle  to  vanifh. 

As  an  univerfal  language,  the  pafigraphy  is  therefore  a  mere  pretenfion  :  but  there  is 
another  point  of  view  under  which  it  may  be  confidered  ;  as  a  philofophical  language, 
better  conflruifled  than  all  our  ancient  languages,  which  are  the  produ6ls  of  chance,  ca- 
price, and  frequently  of  ignorance.  There  is  no  doubt  but  a  profound  metaphyfician,  medi- 
tating at  leifure  in  his  clofet,  and  modeliing  all  his  exprefllons  from  the  type  of  the  original 
ideas,  might  fucceed  in  forming  a  language  more  fimple,  and  in  every  refpedl  fuperior  to 
that  which  we  fpeak.  This  would  be  the  language  which  we  might  then  advife  all  nations 
to  adopt,  if  they  would  confent  to  abandon  their  mother^ tongue  and  acquire  a  language 
common  to  all  men  :  but  this-  language,  perfeft  as  it  might  be,  would  not,  in  its  own 
nature,  be  an  univerfal  language.  We  fhould  always  fpeak  erroneoufly,  if  we  were  to  affert, 
that  the  Portuguefe  and  the  Indian,  each  writing  his  own  language  but  with  other  cha- 
racSlers,  might  underftand  each  other.  On  the  contrary,  we  ought  to  fay,  that  if  both 
acquire  the  philofophical  language,  or  pafigraphy,  they  will  underftand  each  other. 

The  whole  edifice  of  this  pretended  difcovery  is  therefore  reduced  to  the  propofal  of  a 
new  language  more  fimple,  more  accurately  eftabliflied  upon  the  generation  of  our  ideas, 
and  which,  on  that  account,  is  better  adapted  than  any  other  to  become  the  univerfallan- 
guage,  admitting  it  to  be  poffible  to  introduce  fuch  a  general  medium. 

But  this  propofition  is  not  at  all  new,  and  cannot  therefore  be  called  a  difcovery.  It  has 
already  been  made  by  feveral  men  of  the  firft  rank  in  point  of  ability,  who  have  acquired 
nothing  more  than  the  name  of  ingenious  inventors,  without  prevailing  on  other  perfons  to 
fecond  their  efforts. 

A  good  hiftory  of  pafigraphy  would  not  be  an  ufelefs  work  ;  neither  would  it  be  very 
eafy  to  write  fuch  a  treatife.  The  materials  are  fcattered  through  a  multitude  of  fcarce 
books  not  eafy  to  be  colleded. 

In  this  hiftory  we  fhould  fee  what  efforts  have  formerly  been  employed  to  confine 
human  language  within  general  and  determinate  rules  ;  what  principles  have  already  been 
laid  down,  and  the  progrefs  which  this  art  has  made  in  a  few  philofophical  minds.  We 
fhould  judge  to  what  extent  the  modern  pafigraph  has  availed  himfelf  of,  or  departed  from, 
the  ideas  of  his  predeceffors.  We  can  only  prefent  a  few  unconnected  portions  of  this 
hiftory*. 

It  is  known,  that  lord  Bacon  of  V'erulam  comprehended  nearly  the  whole  of  human 
knowledge  ;  that  he  difcerned  almoft  every  thing  which  was  wanting  In  the  entire  fyftem, 
and  forefaw  moft  of  the  difcoveries  which  have  fince  been  made.  He  laid  the  foundations 
of  an  Encyclopaedia,  and  was  very  near  difcovering  various  important  philofophical  refults 

•  In  the  Geniusder  Zeit,  i.  108,  for  the  prerent  year,  an  article  is  found,  to  which  rccourfe  has  been  had  in 
drawing  up  the  prefent  memoir.    Note  of  the  Author. 

Yya  •£ 


344  On  the  Sterns  of  an  tJmverfal  or  PhUofiphkal  Language. 

of  experiments,  fuch  a-s  the  weight  of  the  air,  &c.  If  we  open  his  book  on  the  proprrerg 
of  the  fciences,  we  fliall  find  the  notion  of  a  pafigraphy  in  the  chapter  entitled  The  Inflru- 
ment  of  Difcourfe.  "  It  is  pofTibleto  invent  fuch  figns,"  fays  he,  "  for  the  communication 
of  our  thoughts,  that  people  of  different  languages  may,  by  tliis  means,  untlerflaad  each 
other ;  and  that  each  may  read  immediately,  in  his  own  language,  a  book  which  fliall  be 
written  in  another."  But  Bacon  did  not  think  of  confining  this  to  twelve  charafters  :  on 
the  contrary,  he  requires  a  gieat  number,  at  lead  as  many  as  the  number  of  radical  words  j 
on  which  head  he  quotes  the  example  of  the  Chinefe  ;  "  and  although,"  adds  he,  "  our 
alphabet  may  appear  more  commodious  than  this  method  of  writing,  the  thing  itfelf  is  never- 
thelefs  well  deferving  of  attention.  The  problem  relates  to  the  fignsby  wliich  thoughtb  may 
be  rendered  current ;  and  as  money  may  be  ftruck  of  other  materials  as  well  as  gold  and 
filver,  it  is  polhble  likewife  to  difcover  other  figns  of  things  as  well  as  letters  and  words*." 

Des  Cartes,  in  his  third  letter  to  father  Mcrfennus,  difcufles  the  invention  of  a  French- 
man, whom  he  does  not  name,  but  who,  by  means  of  a  certain  language  and  an  artificial 
writing,  pretended  to  underfland  all  the  different  idioms.  He  remarks  on  this  fubje£t,  that 
it  would  be  very  poflible  to  compofe  a  fhort  and  convenient  grammar,  with  general  figns» 
which  {liould  render  all  foreign  languages  intelligible.  Here  are  already  two  works  on  the 
pafigraphic  art ;  but  we  fhall  proceed  to  exhibit  circumflances  of  a  more  pofitive  nature. 

In  the  year  i66i,  John  Joachim  Becher  publifhed  a  Latin  folio,  the  title  of  which  was 
*'  Charaflers  for  the Univerfal Knowledge  of  Languages:  a  Steganographic  Invention  1  itherto 
unheard  of"  t«  This  unheard  of  invention  was  no  other  thing  than  what  is  now  announced 
to  us  under  the  name  of  Pafigraphy ;  it  is  a  method  of  making  one's  felf  underftood  by  all 
foreigners  by  writing  in  one's  own  language,  and  alfo  of  comprehending  what  they  write  in 
theirs.  It  was  truly  at  that  time  a  thing  unheard  of  ;  for  Becher,  being  the  firfl;  who  had 
given  a  complete  treatife  on  this  art,  may  be  confidered  as  the  inventor.  He  begins  hia 
work  by  a  fet  of  very  delicate  and  highly  interefting  obfervations  upon  general  grammar, 
and  the  fundamental  relations  of  all  languages  with  regard  to  each  other.  He  gives  a 
learned  comparative  table  of  the  relations  and  harmony  of  the  Latin,  the  Greek,  the  He- 
brew, the  Arabian,  the  Sclavonian,  the  French,  and  the  German.  This  work  cannot  be 
too  highly  efteemed,  and  afl'uredly  was  not  unknown  to  the  author  of  the  work  Du  tnonde 
primitif.  A  Latin  diiSionary  then  follows,  in  which  every  word  correfponds  with  one  or 
more  Arabic  numeral  figures  arbitrarily  taken.  Every  number  is  aflumed  as  diftinftive, 
or  denoting  the  fame  word  in  all  languages  ;  and  confequcntly  nothing  more  is  required 
than  to  compofe  a  diftionary  for  each,  finiilar  to  that  which  he  has  given  for  the  Latin. 
There  is  likewife  a  table  of  declenfions  and  conjugations,  which  prefents  certain  determi- 
nate numbers  for  all  the  cafes,  moods,  tenfes,  or  perfons.  By  means  of  this  general  difpo- 
Ction,  when  a  Frenchman  is  defirous  of  writing  to  a  German  the  following  phrafe,  La 
guerre  ijl  un  grand  mal  (war  is  a  great  evil),  he  feeks  in  his  index,  guerre^  etre,  gratid,  mal  \ 
and  he  writes  the  correfpondent  numbers, 

J3)    33»     67,    68. 

♦  T  have  tranflated  from  ray  original,  infleaJ  of  recurring  to  the  book  of  chancellor  Bacon,  which  I  do  not 
pcffefs      The  paffages  marked  as  quotation,  are  not  therefore  the  words  of  Bacon,  but  his  fenfe.     N. 

f  The  author  has  not  given  thcLatin  title  of  this  work.  I  have  therefore  tranflated  his  Freneh  title  word 
lor  word.    N. 

The 


On  the  Syjiems  ef  an  Utiiverfal  or  Philofcphica!  Lattguage,  345 

The  fentcnce  might  ha  undcrftood  by  thefe  four  charadtcriflic  numbers;  but  to  leave  no 
room  for  ambiguity,  he  fays,  Guerre  is  the  nominative  cafe,  and  finds,  as  the  charafleriftic 
of  the  nominative,  the  Arabic  figure  J.  Efl  is  the  third  perfon  fingular  of  t_he  indica- 
tive mood,  prcfcnt  tenfe,  of  wliicli  the  charadleriftic  is  15.  'Yo  grand ^  and  to  inaly  belong 
liliewife  the  figure  i,  for  tlie  nominative  cafe  ;  he  will  therefore  write 

J3-I       I       33'iS       I      67.1       1      68.1       I 
where  the  numbers  are  feparated  by  fmall  vertical  bars  to  prevent  confufion.    It  may  eafily 
be  conceived  how,  by  the  inverfe  method,  the  German  will  find  in  his  tables  the  words  der 
noted  by  the  cyphers,  which  will  form  Der  krjeg  IJI  ein  groffes  uebel. 

This  invention  of  Becher,  which  is  the  fame  thing  nearly  vs-ith  regard  to- language,  as 
algebra  is  to  arithmetic,  could  not  have  cofi:  him  any  great  effort  of  the  imagination  ;  aud- 
it evidently  reduces  itfelf,  as  I  have  obferved  with  regard  to  all  pafigraphy,  to  the  learning 
a  new  language,  or  having  a  ditlionary  at  hand  for  ufe.  It  is  befides  poffefled  of  confider.- 
able  fimplicity,  and  even  a  few  hours  pra£lice  will  render  it  eafy.  If  any  reader  fhould  be 
curious  to  fee  more  applications  of  this  kind,  he  may  have  recourfe  to  the  Latin  work  of 
Sturmius,  Ejpiis  d' Experiences  curieu/es  *. 

In  the  fame  year  George  Dalgaru,  an  Englifhman,  publilhed  at  London,  a  work  of  which 
the  prolix  title  is  fuflicient  to  Hiew  its  obje£l.  It  is,  "  The  Art  of  Signs,  or  an  Unive'rfal 
Character  and  Philofophical  Language,  by  Means  of  which.  Men  of  the  moft  different 
Idioms  may,  in  the  Space  of  two  Weeks,  learn  to  communicate,  whether  by  Word  of 
Mouth  or  by  Writing,  all  their  Thoughts,  as  clearly  as  in  their  Mother-tongue.  Befides 
which,  young  Perfons  may  therein  learn  the  Principles  of  Philofophy,  and  the  Pradice 
of  true  Logic,  more  fpeedily  and  more  readily  than  in  the  ordinary  philofophic  Writinga." 
The  book  of  Dalgaru  is  written  in  Latin  f.  Becman  accufes  him  of  extreme  pedantry.  I 
do  not  know  whether  this  book  is  common  in  England,  but  it  is  very  fcarce  on  the  ContI-  ' 

nent.     His  chara6lers  likewife  were  cyphers. 

Joachim  Frifichius,  profefTor  at  the  Gymnafium  at  Riga,  was  employed  on  a  fimilar  atr 
tempt,  namely,  to  introduce  a  natural,  rational,  and  univerfal  language,  of  which  fomc 
(heets  printed  at  Thorn  in  168  r  may  give  an  idea.  The  death  of  the  author  interrupted 
his  labours.  He  purpofed  to  call  his  new  language  Ludovicean,  in  honour  of  Louis  XIV. 
under  whofe  patronage  he  purfued  his  labours  ;  a  prince  who  extended  his  generoCty  to  the 
learned  of  all  countries. 

The  curious  in  refearches  of  this  nature  may  alfo  find  a  projefl  of  this  kind   in  a  foHo^- 
volume    publifhed  at  Rome    in    1^65,     by    the    celebrated    mathematician    Athanafius- 
Kircher,  the  title  of  which  is,  "  A  New  and  Univerfal  Polygraphia,  deduced  from  the  Art 
of  Combination  %  ;"  and  by  means  of  which,  fays  MorhofF(Polyhiflor.  1.  ii.  c.  j.),  he  who 
underftands  one  fingle  language  only  may  correfpond  in  writing  with  all  the  nations  of' 
the  earth. 

•  I  fuppofe  this  work  to  be  the  Collegium  expetimeniale,  five  cvriojum,  &c.  Jdannis  Chriflopbori  Slurmii,  410.. 
Norimhcrg,  1701.    N.  ^ 

•f-  I  know  nothing  of  this  author,  nor  his  work.     The  title  in  the  text  is  tranflated  verbatim  from  the' 
French.     N. 

X  Neitlier  JVToreri  nor  any  other  biographer  at  prefent  within  my  reach  has  given  the  title  of  _this  work  of 
the  voluminous  Kircher.    N. 

It. 


34^  S)iJlcms  of  Unlvcrfnl  or  PhilofophicaJ  Latiguage. 

It  would  be  perhaps  unjufi:  to  pafs  in  filence  the  Httle-known  work  o£  father  Befnier, 
Jefuit,  who  in  a  book  entitled  La  Reunion  des  Langues,  ou  I'Jrt  dc  les  cipprtndre  toiites  par  nne 
feuU,  that  is,  The  Union  of  Languages,  or  Art  of  learning  all  Language^  by  one  alone, 
printed  at  Paris  in  1674,  has  given  feveral  intimations  which  lead  diredly  to  pafigraphy. 

The  moft  remarkable  work  of  all  whicli  has  been  written  on  this  fubjedl  is,  perhaps,  that  for 
which  we  are  indebted  to  bifliop  Wilkins,  the  brother-in-law  of  Cromwell.  It  is  entitled,  An 
Eflay  towards  a  Real  Charafler  and  a  Philofophical  Language,  London  1668.  It  is  divided 
into  four  parts.  I.  Confiderations  on  the  various  languages,  their  dcfefls  and  imperfeflions, 
from  which  a  philofophical  language  ought  to  be  exempt.  II.  Philofophical  enquiries  re- 
fpefting  all  the  things  and  notions  to  which  proper  names  ought  to  be  aiTigned.  III.  The 
organic  fclence  of  native  grammar  confidered  as  the  necefiary  means  of  reprefenting  f.mple 
ideas  ic  difcourfe,  IV.  The  application  of  the  general  rules  to  every  chara£ler  and  language. 
Examples,  &c.     This  concife  outline  fufficiently  flicws  the  importance  of  the  work  *• 

In  his  appendix,  the  author  explains  the  utility  of  a  method  of  writing  without  alphabetic 
charafters,  by  means  of  figns,  which  are  to  be  ufed  to  denote  all  the  principal  ideas,  the  re- 
lative attributes  being  defignated  by  fmall  firokes  added  at  right,  acute,  or  obtufe  angles,  to 
the  right  or  left,  .&c.  Of  principal  or  chief  ideas  he  admits  but  forty,  under  which  he 
ranges  all  the  others,  by  that  means  forming  a  kind  of  categories.  His  new  language  is 
calculated  to  afford, great  facility  of  comprehenfion,  and  new  openings  to  the  reafoning 
procefles  of  fcience.  A  learner  might  make  more  progrefs  in  it  in  a  month,  than  in  the 
Latin  in  feveral  years  f- 

After  fo  many  attempts  more  or  lefs  philofophical,  and  of  different  degrees  of  perfe£lion, 
with  others  probably  of  which  we  know  nothing,  we  muft  not  overlook  tlie  efforts  of  the 
celebrated  Leibnitz  for  the  introdudion  of  a  pafigraphy.  His  Hiftory  and  Developement 
of  a  Charadleriftic  Univerfal  J  Language  is  in  every  library.  Leibnitz  exhibited,  and  with 
reafon,  his  univerfal  characteriflic  as  the  art  of  inventing  and  judging.  He  was  convinced 
that  an  alphabet  might  be  formed,  and  of  this  alphabet  fuch  words  as  would  afford  a  lan- 
guage capable  of  giving  mathematical  precifion  to  all  the  fcicnces.  "  Men  may  thus  ac- 
quire," fays  he,  "  as  it  were  a  new  organ,  which  would  add  energy  to  their  moral  faculties, 
as  the  microfcopic  lens  increafes  the  power  of  the  eye.     The  compafs  is  not  more  highly 

*  Wilkins's  EfTay  tovfards  a  Real  Charafter  and  a  Philorophical  Language  is  a  tfiin  folio  of  454  pages.  A 
diiSlionary  of  Englifh  words,  referred  to  their  places  in  the  forty  tahlcs,  was  printed  at  the  fame  time  (j 668),  and 
of  the  fame  fize.  Thefe  books  are  not  very  fcarce.  They  contain  a  treafure  of  information  with  regard  to  the 
objefts  comprehended  in  the  fcheme  for  a  philofophical  language  ;  but  neither  this,  nor  the  charafter  itfclf,  as 
the  bifhop  has  left  them,  appears  to  be  enough  completed  to  attraft  the  attention  of  the  world  by  their  facility. 
Dr.  Robert  Hooke,  whofe  prodigious  abilities  give  a  fan<Stioa  to  whatever  he  approved,  did  aftually  learn  it, 
and  publifhed  fome  valuable  philofophical  information  on  an  engraved  plate  in  this  univerfal  charafter,  with  a 
view  to  excite  others  to  acquire  the  means  of  perufal.     N. 

f  The  Chinefe  writing,  which  is  a  very  complicated  pafigraphy,  has  given  two  learned  men  the  idea  of 
forming  one  upon  a  more  fimple  plan.  The  firft  is  Caramuel,  in  his  Apparat  Philofophique,  page  128  ;  and  the 
other  Andrew  Mullcr  GriefTenhag,  in  his  Cle  Cbinoife.  The  latter  promifed  to  teach  to  women  and  children,  in 
the  courfe  of  a  few  days,  a  kind  of  writing  by  which  all  the  feveral  languages  fhould  be  rendered  intelligible  to 
them.     Note  of  the  Author. 

J  Hiftoria  et  commentatio  lingua  cbaraQerica  univerfalis,  qnafiinuljit  an  inveniendi  ei  judiccndi.  Oeuvres 
Philof.  Lat.  et  Franqoifes  dc  Leibnitz,  donnees  par  M,  Rafpe. 

valuable 


On  Utiiverfal  Language. — HiJIory  of  Gvlana,  347 

valuable  to  the  navigator,  than  this  philofophical  language  would  be  to  him  who  embarks 
on  the  fea  of  reafouaiul  experiment,  which  is  now  fo  full  of  clanger." 

We  muft  not  forget  the  ingenious  method  of  the  abbi  de  I'Jipee,  who,  by  means  of  the 
fame  identical  geftures,  dictated  to  his  deaf  and  dumb  pupils  certain  difcourfes,  which  they 
wrote  with  equal  readinefs  in  four  languages.  Nothing  can  more  afluredly  refcmble  a  true 
pafigraphy  than  thefe  gedures. 

The  abbe  de  Condillac,  a  fubtle  metaphyficlan,  particularly  with  regard  to  human  lan- 
guage, has  not  negle£ted  figns  and  characters.  In  his  Art  of  Thinking  (^Art  de penfer), 
in  his  Art  of  Writing  [Art  d'ccrire),  and  more  particularly  in  his  Logic,  he  has  fliewa 
the  advantages  of  a  philofophical  language,  which  fhould  proceed  perfectly  in  the  order' 
of  the  ideas,  and  of  which  the  figris  fliould  be  the  mod  fimple  and  analytical.  He  ex- 
prefsly  reduces  the  ftudy  of  all  the  fciences  to  that  of  a  well  conftrudled  language,  and 
quotes,  as  an  example,  algebra  in  the  mathematical  fciences. 

Strengthened  by  fuch  alFillance,  fupported  by  the  refearches  of  fo  many  predeceflbrs.  If: 
rauft  no  doubt  have  been  eafy  for  Citizen  Memieux  to  have  conceived  and  executed  the 
idea  of  a  pafigraphy.  To  judge  how  far  he  is  an  inventor,  to  diftinguifh  what  exclufively 
belongs  to  him,  it  is  neccflary  to  examine  and  perpetually  compare  his  work  with  all 
thofe  we  have  pointed  out,  and  no  doubt  with  many  others  which  have  efcaped  our  notice. 

Will  this  new  author  be  more  fortunate  than  Becher,  Kircher,  Wilkins,  and  Leibnitz  ? 
Will  he  eafily  perfuade  the  nations  to  learn  the  new  language  he  propofes  ?  Of  this  we 
may  ftill  reafonaiily  entertain  fome  doubt.  However  this  maybe,  it  is  to  be  hoped  that 
a  pafigraphy  will  hereafter  be  ettabliflied.  In  thofe  ages  of  peace,  leifurc,  and  union, 
of  which  the  profpeft  is  held  out  to  us  by  M.  Kant,  men  will  have  no  obje£l  of  more  . 
importance  than  to  give  perfeftion  to  their  language,  and  to  liften  to  the  voice  of  philo« 
fophers,  who  fhall  propofe  to  them  a  better  fyftem  of  fpeech.  If  it  fhould  not  be  admitted 
in  the  lower  clades  of  fociety,  it  will  at  leaft  become  the  learned  language  of  all  the 
earth.  On  this  fubje£l  I  will  venture  to  ground  a  comfortable  hope,  which  tends  to  en- 
courage the  mind  under  its  aftonifhment  at  the  dreadful  deluge  of  books  which  at  prefent 
inundates  the  world. — Thofe  books  only  will  be  tranflated  into  the  learned  language  which 
deferve  the  trouble  :  the  moft  falutary  fcrutiny  will  take  place  ;  and  the  reft  will  go  to  heat 
the  baths.  Philofophers,  literary  men,  authors  of  every  defcription,  be  affiduoui,  compofe 
■works  of  value,  and  be  aflured  that  your  writings  and  your  names  will  efcape  oblivion 
by  means  of  the  pafigraphic  invention.  In  the  mean  time,  till  the  arrival  of  this  great 
epocha,  one  of  the  languages  at  prefent  in  ufe,  one  of  the  moft  imperfedl  in  many  re- 
fpefls,  becomes  every  day  more  extended   in   its  ufe  ***** 


V. 

Ohfervations  on  the  Natural  H'ljlory  of  Guiana.      In  a   Letter  from   WiLLIAM  LoCHEADy 
E'q.  F.R.S.  Edin.  to  the  Rev.  Dr.  Walker,  F.R.8.  Edin,  Regius  Profeffor  of  Natural . 
Hijiory  in  the  Univerfity  of  Edinburgh. 

[Concluded  from  Page  304,  Vol.  II.J 


B. 


►ESIDES  thefe  two  kinds,  there  are  alfo  what  we  may  denominate  half  favannahs, 
formed  upon  the  tops  of  fand-hills,  higher  and  more  irregular  than  in  the  cafe  of  thofe  jufl 

defcribed. 


348  '  0«  the  Natural  Hijory  of  Guiana. 

defcribed.  Some  of  thefe  are  alfo  very  extenfive.  Few  herbaceous  vegetables  are  to  be 
met  with  upon  them.  Broad  fpaces  of  arid  fand  are  interfered  by  clumps  of  flirubbery. 
Nothing  grows  to  the  height  of  a  tree  ;  but  a  particular  fet  of  plants,  different  from  thofe 
in  other  parts  of  the  country,  find  fubfiftence  enough  to  rife  to  fifteen  or  thirty  feet.  How 
Nature,  after  all  her  efforts,  fhould  have  failed  to  induce  a  foil  upon  thefe  is  furprifing.  It 
appears  chiefly  owing  to  the  great  porofity  of  the  fand,  which  every  where  admits  the  de- 
cayed vegetable  matter  deftined  for  that  purpofe  to  be  carried  down  through  it,  and  filtered 
ofFby  the  rain.  Even  thofe  fand-hills  which  are  covered  by  tall  trees,  (till  fhew  proofs  of 
this.  The  trifling  layer  of  mould  formed  upon  them  is  exceedingly  thin.  When  cleared, 
they  are  very  barren  ;  and  when  you  dig  in  them  to  a  great  depth,  you  flill  find  fmall  por- 
tions of  black  vegetable  earth  difperfed  among  the  fand.  What  corroborates  the  above 
liippofition  is  the  appearance  of  the  fprings.  Abundance  of  thefe  are  found  gufhing  out 
copioufly  round  the  verges  of  the  hills ;  and  notwithftanding  the  extreme  whitenefs  and 
purity  of  the  fand  from  whence  they  flow,  there  is  not  one  in  an  hundred  whofe  waters 
are  limpid.  They  come  -out  not  muddy,  but  of  a  brownifh  colour,  very  much  like  the 
water  which  runs  from  peat-molTes,  and  they  are  certainly  tinged  by  the  fame  caufe.  The 
rotten  leaves  of  trees,  and  other  decayed  parts  of  vegetables  on  the  hills,  inftead  of  being 
colledled  on  the  furface  to  form  foil,  are  wafhed  down  into  the  fand  (trata  by  every  rain ; 
fo  that  the  refervoirs  of  the  fprings,  and  the  water  which  proceeds  from  them,  are  always 
coloured  with  thefe  fubftances.  There  follows  a  corollary  alfo  from  this  general  principle, 
and,  when  compared  with  fads,  1  believe  it  will  hold  good  :  The  more  the  fand  is  con- 
creted into  ftone  in  any  of  the  hills,  the  more  and  better  will  be  the  foil  upon  them.  Where 
clay  in  fmall  beds,  or  in  a  certain  proportion,  is  mixed  with  the  fand,  the  vegetable  mould 
will  likewife  be  better  retained.  , 

Rivers. — I  will  next  give  you  what  general  obfervations  I  have  been  able  to  make  upon 
the  rivers  and  creeks  of  this  part  of  America.  The  courfe  of  nearly  qll  thofe  of  Guiana  is 
from  fouth  to  north.  They  originate  in  a  chain  of  hills  running  eaft  and  wefl,  which  fepa- 
rates  Guiana  from  the  country  of  the  Amazons,  and  likewife  gives  rife,  on  its  fouth  fide,  to 
the  numerous  branches  which  fall  into  that  river.  The  Demerary  is  a  confiderable  ftream, 
equal  if  not  fuperior  to  the  Thames  ;  yet  it  is  by  no  means  among  the  largeft  of  them. 
The  ElTequebo  is  five  times  larger  at  its  mouth,  forming  a  whole  Archipelago  of  iflands ; 
but  its  ftream  foon  divides,  and,  on  account  of  rocks,  fliallows,  and  rapids,  none  of  its 
branches  are  navigable  fo  high  up  as  the  former.  Moft  of  the  particulars  I  am  now  to  give 
you,  muft  be  underflood  as  applying  to  the  Demerary.  The  bar,  if  it  may  be  fo  called,  is 
common  to  this  with  many  other  rivers  which  difcharge  themfelves  into  a  fhallow  fea ;  but 
ftill  with  circumftances  in  the  prefent  cafe  which  diftinguifh  it  from  others  where  the  bot- 
tom is  not  mud  but  fand.  It  does  not  run  like  a  fingle  narrow  ridge,  acrofs  or  nearly 
acrofs  the  mouth  of  the  river ;  but  it  is  of  great  extent,  and  is  properly  a  continuation  of  the 
mud-bank  which  runs  all  along  the  coaft.  To  the  eaft  and  weft,  and  for  two  miles  or  more 
in  the  ofEng,  you  have  ten  or  twelve  feet  water,  with  the  utmoft  uniformity  ;  and  ftanding 
in  with  the  mouth  of  the  river  open,  you  neither  deepen  nor  (hallow  till  you  enter  it,  when 
you  fir^two,  three,  four,  and  five  fathom;  and  it  continues  to  average  that  depth  for  a 
long  way,  fo  that  any  veflel  which  can  enter,  may,  for  draught  of  water,  proceed  up  the 
jriver  for  100  miles  or  more. 

The 


On  the  Natural  Hijiory  of  Guiana.  349 

The  mouth  of  the  Eflequebo,  from  the  fand-hills  and  rocks  being  very  near  It,  is  exceed- 
ingly different.  Three  large  iflands  prefent  themfelves  in  a  breaft,  and  divide  its  entrance 
into  four  channels.  The  length  of  thefe  iflands  is,  with  the  current,  fouth  and  north  ;  and 
from  the  tail  or  north  end  of  each  of  them,  as  alfo  from  the  banks  of  the  main,  or  either 
fide,  run  out  fand- banks  to  a  gbod  diftance.  They  are  perfe£lly  firm,  quick  in  very  fe\T 
fpots,  and  the  body  of  them  is  above  the  level  of  low  water.  On  the  outfide  of  them,  you 
have  the  continuation  of  the  mud-banks  and  fliallow  water,  as  above,  only  that  the  en- 
trance of  thefe  channels  is  dill  (hallowcr  than  that  of  the  Dcmerary.  The  dream  of  this 
river  runs  very  brown  and  muddy,  and  the  fea  is  ftained  with  it  for  fome  leagues  off.  A 
granger  naturally  imputes  this  to  the  wafhings  of  a  large  flat  country,  or  the  llirring  up  of 
the  muddy  bottom  by  the  tides.  The  latter  may  in  part  be  a  caufe,  though  1  believe  it  con- 
tributes to  it  but  very  little,  and  the  former  in  a  (late  of  uncultivatlon,  none  at  all.  On 
afcending  forty  miles  or  fo,  you  find  the  water  clear  again,  or  rather  of  a  darkifli  hue  ;  and 
fo  it  continues  above  that.  I  was  at  firft  at  a  lofs  how  to  account  for  this;  but,  from  a 
number  of  circumdances,  was  foon  led  to  conclude  that  the  thickncfs  and  light  brown 
colour  of  the  water  near  the  mouth  of  the  river,  and  on  the  coad,  were  almod  entirely  the 
effeft  of  cultivation.  Numberleis  ditches  and  canals  have  been  opened  by  the  inhabitants, 
which  are  receiving  or  difcharging  water  every  tide  ;  and  each  particular  piece  on  a  planta- 
tion is  every  way  interfered  with  open  little  drains,  which  communicate  with  thefe  ditches. 
In  digging  and  hoeing  this  clayey  foil,  much  of  it  is  fufpended  in  the  water,  and  carried  off 
by  the  current  of  the  tides.  Nothing  can  be  more  certain,  than  that  all  up  the  river,  anJ 
in  all  the  creeks  which  difchargc  themfelves  into  it,  the  colour  of  the  water  is  condantly 
clear  or  blackidi,  even  in  the  rainy  feafons  when  it  is  fwollcn.  On  confidcring  thefe  cir- 
cumdances, I  have  been  led  to  this  general  conclufion,  which  is  fubmitted  to  the  proof  of 
obfervation  in  different  parts  of  the  world.  The  reddlfli  brown  colour  fo  common  in 
ireflies  of  rivers  in  Europe,  and  we  may  add  every  where,  is  almod  entirely  the  effe£l  of 
cultivation ;  and  the  natural  colour  of  rivers,  even  in  the  highed  and  longed  continued' 
floods,  where  all  the  country  is  ftill  in  woods  or  padures,  is  ever  that  of  a  dark  brown,  or 
blackifli,  pretty  much  like  that  of  the  ftreams  which  rife  among  peat-moffes,  but  rather  more 
diluted.  It  is  comparatively  very  clear,  and  depofits  but  a  trifling  fediment.  The  other 
is  thick  and  opaque,  and  its  fediment  copious.  Thus  is  man,  in  his  little  workings,  made  in 
a  fmall  degree  one  of  the  engineers  of  Nature.  We  cannot  doubt  that  entire  drata  will 
owe  to  him  their  exidence,  accumulated  in  a  feries  of  ages  at  the  bottom  of  the  fea,  and 
deftined  in  future  revolutions  to  aft  a  more  diftinguidied  part.  It  may  be  curious,  too,  to 
confider  the  differences  that  may  be  expe£led  betwixt  the  drata  formed  by  thefe  different 
depofitions,  which  may  be  fuppofed  between  them  to  have  been  the  origin  of  mod  of  the 
clays  upon  our  globe.  Clay,  earth,  or  loam,  dirred  up  by  the  labourer,  gives  rife  to  the 
one  :  minutely  decayed  parts  of  vegetables  form  the  body  of  the  other. 

It  mud  alfo  be  obferved,  that  clearing  the  ground  along  the  coad,  by  cutting  down  treci, 
and  opening  ditches  for  the  difcharge  of  water,  has  expofed  the  land  very  much  to  the 
wafliing  of  the  fea.  The  roots  of  the  mangroves  formed  a  plexus  able  to  refid  its  force, 
and  the  former  equal  and  very  flow  deepening  of  the  water  prevented  its  making  a  ftrong 
impreffion  on  any  place.  The  difcharge  from  the  ditches  at  low  water  cut  out  channel* 
in  the  mud,  and  left  the  fides  of  thefe  channels  more  expofed  to  the  returning  waves,  which 

Vol.  II.— Nov.  1798.  Z  z  ^^^ 


-  350  0»  the  Natural  Hlflotj  aj  Guiana, 

here  beat  continually  upon  a  lee  fliore.  We  find  therefotc  on  the  coaft,  that  the  fea  ha« 
made  here  and  there  confiderable  encroachments,  which  generally  begin  on  the  weft  fide  of 
the  canals  or  ditches,  as  being  the  moft  afted  upon  by  the  waves.  The  mouth  of  the  De- 
nierary  itfelf  furnifties  us  with  a  ftrong  iiidance.  That  river  is  now  nearly  twice  as  wide  as 
it  was  when  the  country  firft  began  to  be  cleared,  the  fea  and  the  ftream  together  having 
fince  that  fwept  away  a  large  portion  of  land  from  the  weftern  fhore. 

Creeks.  — A  number  of  creeks  fall  into  the  Demerary  on  both  fides,  but  fo  fmall  that  they 
bear  no  proportion  to  the  fize  of  the  river.  You  can  hardly  diftiriguifli  their  mouths  in  the 
woods  which  overhang  the  banks.  They  are  fo  narrow,  that  it  is  difficult  to  run  a  fmall  boat 
in  them  ;  yet  you  will  find  in  them  throughout  from  two  and  a  half  to  four  fathom  water, 
and  they  run  winding  fo  far  back  that  it  will  take  five,  fix,  eight  hours,  or  more,  to  carry 
you  up  to  their  heads,  where  they  terminate  In  fmall  ftreams  from  among  the  fand-hllls. 
The  banks  of  the  creeks,  at  their  mouths,  are  of  the  fame  height  as  thofe  of  the  river  clofe, 
from  five  perhaps  to  twelve  feet  above  the  water  in  the  dry  feafon.  As  you  afcend  the 
creek,  you  might  naturally  expect  to  find  them  rife.  It  is,  however,  the  very  reverfe  ; 
they  become  gradually  lower  and  lower,  till  at  lafl:  all  round  them  is  a  fwanip :  and  the 
trees  on  each  fide,  in  like  manner,  become  fmaller  and  fmaller,  and  of  different  fpecles 
from  what  they  were.  It  is  now,  in  fhort,  exactly  a  mangrove  fwamp,  with  this  difference, 
that  the  water  is  quite  frefli,  the  vegetables  are  not  the  fame,  and  there  are  abundance  of 
arunis  and  other  low  herbaceous  plants.  A  little  higher  up,  you  lofe  the  wood  altogether, 
and  find  yourfelf  in  a  beautiful  deep  canal,  winding  through  a  fpaclous  wetfavannah,  which 
is  fometimes  many  leagues  in  circumference.  The  firft  time  we  went  up  one  of  thefc 
creeks  (called  CamounI),  I  was  furprifed  at  this  appearance,  and  thought  it  muft  be  a  mere 
local  circumftance  peculiar  to  It.  We  found  afterwards  the  fame  in  one  or  two  more  in- 
ftances,  and  were  fatisfied  upon  enquiry  that  it  Is  common  to  them  all.  It  was  natural  to 
look  for  an  explanation  of  this  phenomenon,  and  I  foon  found  It  in  one  of  thofe  laws 
which  probably  extend  to  all  rivers  fubje£l  to  frequent  inundations.  It  has  been  obferved 
in  particular  of  the  Ganges  *,  that  the  banks  of  that  river  are  higher  than  the  adjacent 
lands  at  a  diftance  from  the  ftream,  owing  no  doubt  to  the  annual  depofitions  of  mud, 
&c.  during  the  fwell  of  the  river.  Apply  the  fame  rule  to  the  Demerary,  and  the  dilfi- 
culty  will  be  folved.  The  wet  favannahs  behind,  and  the  fwampy  woods  around  them, 
are  the  body  of  the  low  country,  at  Its  natural  level  fcarcely  a  foot  or  two  above  the  fea. 
Whatever  additional  height  the  land  has  in  the  vicinity  of  the  river,  from  the  time  you 
have  afcended  about  twenty  miles  or  fo,  is  all  acquired.  It  has  rifen  from  the  fedlment 
of  the  river  during  the  rainy  feafon,  when  the  country  is  overflowed,  fo  as  that  all  the 
lower  part  of  it  is  under  water.  This  depofitlon  muft  be  always  more  copious  in  propor- 
tion as  It  is  nearer  the  ftream,  where  additional  quantities  are  always  brought,  and  where 
It  is  kept  in  motion  both  by  the  current  and  the  tide. 

Every  thing  we  afterwards  faw  confirmed  this  theory,  and  nothing  more  directly  than 
the  canals  which  run  out  at  right  angles  from  the  river.  Some  of  thefe  extend  four  miles 
inward,  and  they  prove  to  a  demonftratlon  that  the  land  becomes  lower  and  lower  the  far- 
ther you  recede  from  the  river.     The  maps  of  the  colonies  confirm  it ;  for  in  all  of  them 

•  Account  of  the  Ganges,  &c.  Phil.  Tranf.  1781,  by  Major  Rennell. 

the 


On  the  Natural  Hi/lory  of  Guiana.  35 1 

the  main  body  of  the  low  land  of  Guiana  is  laid  down  as  favannah  ;  and  the  woody  coun- 
try, which  a  ftranger  or  fuperficial  obferver  would  fuppofe  to  be  the  whole,  or  much  the 
greater  part  of  it,  is  in  fad  only  a  border  on  the  fides  of  the  rivers  and  of  the  fea,  but  of 
confidcrable  breadth,  more  or   lefs  iii  proportion  to  the   fize  of  the    adjoining  river,  or, 
which  is  generally  the  fame  thing,  to  the  acquired  height  and  extent  of  the  foil  on  either 
bank.     It  fellowed  as  a  confcquence,  and   as  far  as  we  had  opportunities  of  obferving' 
found  it  to  be  the  cafe,  ihat   the   low   land  was    fomewhat  higher,  and   continued   fo 
farther  down  about  the  Eflequebo,  than  the  Demerary  ;  the  woods,  confequently,  were  of 
greater  extent.     We  found,  befides,  in  the  foil  adjoining  the  Eflequebo,  at  leaft  upon  the 
caft  fide,  a  mixture  of  fand.      The  river  is  full  of  fand-banks ;  and  it  appears,  that  the 
finer  parts  of  even   this   lefs  fufpenfible  fubftance  are  raifed  by  the  floods,  and  carried 
among  the  adjacent  woods,  to  be  depofited  with  the  mud.     The  Mahayka,  a  fmall  river 
or  creek,  which  falls  into  the  fea  about  twenty  or  thirty  miles  to  the  eaftward  of  the  De- 
merary, though  it  runs  a  long  way  up  the  country,  and  fpreads  into  many  branches,  has 
but  a  very  narrow  and  often  interrupted  border  of  wood  upon  its  banks  ;  it  runs  through 
an  immenfe  favannah,  and  fo  do  its  branches,  with  little  or  no  wood  till  they  approach 
the  fand-hills.     The  Deltas  of  the  river  of  Oronooko,  and  its  numerous  mouths,  make  a 
figure  even  in  the  map  of  the  world.     It  is  to  be  regretted  that  itsnoble  flream  has  been 
fo  long  hid  from  fcience.     What  I  learned  in  Trinidad,  from  a  gentleman  who  had  failed 
from  its  mouth  to  the  Angufturas,  about  300  miles  up,  confirms  and  illuftrates,  in  the 
fulled  manner,  the  above  general  rule.     The  weftern  mouths  of  it,  oppofite  Trinidad, 
are  navigable  only  for  launches  drawing  fix  or  feven  feet  water.     At  and  oppofite  them 
the  bottom  is  fliallow  and  muddy,  and  the  coaft  a  low  mangrove  fwamp,  refembiing  in  all 
refpefls  that  of  Guiana.     You  mud  afcend  thofe  branches  feveral  days  before  you  reach 
the  main  dream  ;  and  in  doing  fo  you  find  the  fame  phenomena  as  in  afcending  the  De- 
merary, but  in   a  dill  greater  degree.     At  fird  you  have  the  mangrove,  or  fome  fimilar 
fwamp,  and  behind  it,  on  both  fides,  for  about  twenty  leagues,  the  land,  if  you  can  call 
it  fo,  hardly  emerging  from  the  water.     Afterwards  the  ground  appears  ;  and,  as  you  go 
up,  rifes  dill  higher  and  higher  on  the  banks  above  the  common  level  of  the  dream.    The 
trees  become  in  the  fame  manner  of  different  fpecies,  and  much  taller  than  they  were  below. 
The  channel  in  which  you  are,  from  being  wide  grows  narrower  by  degrees.     It  is  from 
about  one  and  a  half  to  three- fourths  of  a  mile  broad  near  the  entrance,  and  when  it  joins 
the  main  dream  is  not  more  than  about  200  yards.     It  has  then  acquired  a  confidcrable 
depth,  and   the  banks   may  be  about  20  feet  high.     Along  the  main  dream  of  the  river, 
or  Boca  de  Nafios,  the  gradual  rife,  and  other  circumdances  attending  it,  are  quite  fimilar. 
All  this  height  of  the  bank,  I  can   make   no  doubt,  is  entirely  acquired  ground,  formed 
by  the  fediment  of  the  floods,    greater  near  the   dreams    than   at   a  didance  from  them  ; 
and  though  I  have  no  knowledge  of  the  nature  of  the  land  in  the  Deltas  and  their  vici- 
nity, 1  would  not  hefitate  to  fay,  that  great  part  of  the  interior  body  of  each  iiland,  and 
mod  probably  of  the  main,  on  either  fide  where  it  is  low  country,  confids  of  nothing 
clfe  than  wet  favannnahs. 

Floods. — Before  we  leave  the  rivers,  It  may  be  proper  to  take  notice  of  their  floods.  In 
no  indance  of  a  large  river  does  the  univerfal  law  within  the  tropics  fail,  that  they  an- 
nually overflow  their  banks  for  a  certain  feafon.     What  was  a  prodigy  in  the  Nile  during 

Z  z  2  the 


35  a  On  the  Natural  Hijory  of  Guiana. 

the  infancy  of  fcicncc,  is  now  a  well-known  phenomenon  to  every  inhabitant  of  a  conti. 
nent  in  the  torrid  zone.  From  the  fituation  of  the  river  Amazons,  it  amounts  to  a  cer- 
tainty, that  the  Demerary,  Eflequebo,  and  other  rivers  of  Guiana,  cannot  originate  very 
far  up  in  the  continent  of  South  America.  This  is  confirmed  by  what  I  could  learn  of 
the  rife  and  duration  of  the  floods  of  thefe  two  rivers.  Enquiring  about  them  at  the 
plantations  below  is  to  little  purpofe,  for  there  the  floods  are  hardly  difcernible  j  but  by 
the  poll-holder,  and  the  fettlcrs  farthcft  up,  I  was  informed  that  they  are  there  feiifible 
enough,  and  that,  independent  of  all  partial  fwells  from  accidental  rains,  the  Demeriiry 
generally  rofe  every  year  in  the  month  of  June,  and  continued  high  through  July  and 
part  of  Auguft.  The  rife  there  upon  the  whole  might  be  about  twelve  feet ;  it  is  fufii- 
cient  to  lay  the  level  parts  of  the  country  under  water,  and  to  render  the  woods  that 
cover  them  in  feveral  places  pafluble  in  canoes.  We  could  have  willied  for  more  esa£l 
information.  This,  however,  was  fufilcient  to  prove  that  the  rivers  did  not  rife  very  far 
inland,  elfe  the  floods  would  have  been  later  in  the  year  ;  but  at  the  fame  time  that  they 
were  of  extent  enough  to  follow  the  rule  of  all  confiderable  intertropical  rivers,  fo  as  to- 
have  a  flood  in  the  rainy  feafon,  that  is,  in  the  months  when  the  fun  is  upon  the  fame  fide 
of  the  line  on  which  they  have  their  origin  and  courfe. 

The  great  Oronooko,  I  have  been  informed,  begins  to  rife  a  little  in  May  :  it  conti- 
nues increafing  through  the  fummer  months,  and  the  inundation  is  at  its  height  in  Sep- 
tember. At  that  time,  as  far  up  as  the  Angufturas,  the  rife  is  above  forty  feet  perpendi- 
cular above  the  low  water  mark.  It  diminiflies  as  you  defcend,  till  about  the  mouth,  where 
it  is  only  a  very  few  feet. 

Tides  are  of  the  utmoft  confequence  to  the  inhabitants  of  the  coaft  of  Gniana.  They 
enable  them  to  drain  a  country  which  otherwife  would  never  have  been  cleared,  and  they 
afcertain  their  journeys,  which  are  made  by  water  up  and  down  the  rivers,  and  even  along 
the  coall.  At  the  mouth  of  the  Demerary  it  is  high  water  at  about  half  part  five,  at  new 
and  full  moon.  The  rife  in  fpring  tides,  a  little  way  up,  is  twelve  feet  or  more  above  low 
water  mark.  The  tide  runs  very  rapidly  near  the  mouth  of  the  river,  fcldom  lefs  thai* 
four  or  five  miles  in  the  hour.  It  continues  to  run  with  force  for  a  long  way  up,  and  was 
fufficient  without  wind  to  carry  us  up  or  down  at  150  miles  from  the  mouth.  Above  that 
it  becomes  feebler;  and  for  a  confiderable  difl;ance  below  the  Rapids,  though  there  is  a^ 
fenfible  rife  and  fall  of  two  or  three  feet,  yet  even  in  the  dry  feafon  the  current  is  con- 
ftantly  down,  only  more  gentle  during  the  rife  or  flood  ;  and  there  alfo  the  continuance 
of  the  rife  is  very  fhort,  not  more  than  two  or  three  hours. 

Some  obfervations  upon  the  foil  of  the  different  parts  of  the  country  may  be  the  fub- 
je£l  of  a  future  communication.  I  will  only  add,  at  prefent,  what  I  think  has  more  than 
conjectural  foundation ;  viz.  that  this  moft  recent  of  countries,  together  with  the  large 
additional  parts  ftill  forming  on  its  coait,  appear  to  be  the  prod  unions  of  two  of  the 
greateft  rivers  on  the  globe,  the  Amazons  and  the  Oronooko.  If  you  caft  your  eye  upon 
the  map,  you  will  obferve,  from  Cayenne  to  the  bottom  of  the  Gulph  of  Paria,  this  im- 
menfe  tra£t  of  fwamp,  formed  by  the  fediment  of  thefe  rivers,  and  a  fimilar  tra£l  of 
fhallow  muddy  coaft:,  which  their  continued  operation  will  one  day  elevate.  The  fedi- 
inent  of  the  Amazons  is  carried  down  thus  to  leeward  (the  weflwardj,  by  the  conftant, 
Oirrents  which  fet  along  from  the  fouthward  and  the  coafl  of  Brazil,  That  of  the  Oro- 
nooko 


Immerjion  tn  Fermented  Liquors  fatal  t9  Infe/tj.  geq 

nooko  is  detained,  and  allowed  to  fettle  near  its  mouths,  by  the  oppofite  iflands  of  Tri- 
nidad, and  ftill  more  by  the  mountains  on  the  main,  which  are  only  feparated  from  that 
ifland  by  the  Bocos  del  Drago.  The  coaft  of  Guiana  has  remained  as  it  were  the  great 
eddy  or  refling-place  for  the  wafhings  of  great  part  of  South  America  for  ages  ;  and  its 
own  comparatively  fmall  dreams  have  but  modified  here  and  there  the  grand  depofit. 

W.  LOCHPIEAD. 


VI. 


On  the  fuppofed  Revival  of  Infers  after  long  Immerfion  in  Wine  or  ether  intoxicating  Li' 

quor.    By  Mr.  John  Govgh. 


Tc 


To    Mr.    NICHOLSON. 

SIR.  Kendal,  Oft.  7,  i79«. 


O  attack  the  opinions  of  any  man  is  a  difagreeable  tafk,,  efpecially  if  fuch  opinions. 
have  been  favoured  by  perfons  of  the  firft  reputation  in  their  refpedlive  purfuits.  The 
force  of  the  preceding  refle£lion  has  embarraflcd  me  not  a  little  in  my  prefent  attempt,, 
which  prefumcs  to  controvert  a  notion  relative  to  the  nature  of  infefts,  fupported  by  the 
authority  of  Dr.  Franklin.  This  acute  and  induftrious  philofopher  maintains,  that  flies 
drowned  in  wine  will  revive,  days,  or  even  months,  after  their  immerfion,^  upon  being  ex~ 
pofed  again  to  the  air  and  fun.  The  Dodlor  does  not  profefs  himfelf  to  be  the  author  of  the 
opinion,  but  fuppofes  he  faw  it  confirmed  by  an  incident  which  he  witnelTed  in  London,. 
where  difcovering  two  flies  in  a  veflel  that  was  employed  to  decant  a  bottle  of  iMadeira. 
wine  that  had  been  brought  from  Maryland,  and  concluding,  perhaps  too  haftily,  tliat  the 
flies  were  imported  from  America  in  the  bottle,  he  expofed  them  to  the  fun  :  one  of  the: 
two  revived  in  a  little  time,  and  flew  away  ;  but  the  other  could  not  be  reftored  to  life  by? 
this  artlefs  method  of  refufcitation.  After  ftating  the  fa£l,  the  DoiTtor  proceeds  to  ea- 
tertain  his  readers,  according  to  his  cuftom,  with  fome  lively  refleftions,  which  would; 
have  been  not  lefs  important  than  they  are  amufing,  had  the  premifes  been  well  founded  j, 
but  I  am  perfuaded  that  a  more  careful  repetition  of  the  experiment  would  have  determinedt 
this  ingenious  obferver  to  relinquifti  a  notion  which  his  high  name  has  made  current  withi 
the  phyfiologiftsof  the  prefent  day. 

In  order  to  obtain  that  information  and  certainty  refpcfling  the  fubje£l  which  cannot 
be  had  from  cafual  obfervations,  I  have  repeated  the  experiment  on  a  number  of  infefts, 
drowned  for  the  purpofe  in  wine  and  other  intoxicating,  liq^uors ;  an  account  of  which, 
trials  is  related  in  the  fequel  of  this  letter. 

Experiment  I.  Two  large  blue  flelh  flies  {mufca  vomitoria),  which  had  been  immerfed 
in  a  phial  of  red  wine,  with  a  view  to  this  experiment,  on  the  12th  of  July  1793,  wer& 
expofed  again  to  the  fun  and  air,  on  a  piece  of  black  filk,  in  a  window,  on  the  20th  of 
Auguft  the  year  following.  In  this  fituation  they  remained  two  days  without  Ihewing 
any  figns  of  returning  life  ;  on  the  contrary,  they  were  found  dry  and  fhrivelled,  though, 
their  bodies  appeared  plump  and  in  high  prefervation  when  taken  out  of  the  bottle.. 

Experiment  2.  1  repeated  the  preceding  experiment  on  a  number  of  flies,  making  ufe- 
of  Madeira  and  otbcic  kinds  of  wine,  as  well  as  brandy  and  beer  j  the  time  of  iramerfioa 


354  Jtnmerfton  in  Fermented  Liquors  fatal  to  InfeSli. 

being  varied  from  'two  hours  to  three  or  even  four  days ;  but  the  fame  virant  of  fuccefs 
attended  all  thefe  trials ;  for  not  one  fly  which  had  been  rendered  torpid  by  intoxication 
could  be  reftored  to  life. 

Experiment  3.  Files  which  were  taken  out  of  the  wine  two  or  three  minutes  after  they 
ceafed  to  fhew  indications  of  life,  recovered,  not  only  when  expoi'ed  to  the  fun,  but  alfo 
when  placed  in  a  temperature  kept  high  by  means  of  the  human  breath  for  the  fpace  of 
fix  or  eight  minutes. 

'  The  two  firft  experiments  taken  in  conjunftion  with  the  lad  feem  to  infinuate,  that  the 
doftor  was  deceived  in  fuppofing  his  flies  to  have  been  imported  from  America  ;  for  the 
cagernefs  with  which  thefe  infe£ts  repair  to  veflels  containing  fpiiituous  and  fermented 
liquors,  makes  it  much  more  probable,  that  they  were  attra£led  by  the  fmell  of  the  wine 
into  the  funnel,  from  which  they  were  extricated  in  a  little  time,  but  not  before  one  of  the 
two  had  been  too  long  immerfed  to  recover ;  and  unlefs  fome  circumftances  of  importance 
have  been  overlooked  in  the  preceding  attempts,  flies  made  infenfible  by  vinous  fpirit  are 
fubje£led  to  the  fame  law  of  fufpended  animation  which  determines  the  fate  of  animals 
drowned  in  water. 

I  will  even  venture  to  advance  a  more  decifive  propofition  on  this  head,  in  pronouncing 
alkohol  highly  pernicious  to  the  living  principle  in  infedts,  which  it  deftroys  with  certainty, 
but  not  with  equal  expedition  in  every  kind  ;  for,  if  the  effefts  of  this  fluid  on  thefe  dimi- 
nutive animals  be  compared  with  the  injuries  they  experience  in  the  air-pump,  intoxication 
will  appear  to  kill  them  in  a  much  fhorter  time  than  the  abfence  of  oxygen.  Dr.  Derham 
found,  that  feveral  infefls,  which  he  fpecifies,  revived  on  the  re-admifljon  of  the  air,  after 
remaining  torpid,  in  fome  inftances,  as  long  as  16  hours  in  an  exhaufted  receiver.  (See 
Phyfico-Theology,  chap.  1.  note  F.)  But  life  feems  to  be  extinguifhed  in  a  much  fhorter 
period  by  fpirituous  liquors. 

The  foregoing  experiments  be'ng  confined  to  common  flies,  or  thofe  with  one  pair  of 
wings,  I  thought  it  not  improper  to  extend  the  enquiry  to  a  greater  variety  of  infedls,  which 
was  done  accordingly  in  the  courfe  of  the  laft  fummer.  But  thefe  trials  d:fcovered  nothing 
remarkable,  except  the  power  of  the  Nut  Weevil  (Curculio  Nuciimj  to  refift  the  deftruftive 
effects  of  alkohol  *.  This  conflitutional  Angularity  has  been  noticed  prior  to  the  prefent 
cfl^ay  ;  but  unlefs  my  experiments  were  made  under  fome  unfavourable  circumftances, 
the  property  in  queftion  appears  to  be  exaggerated. 

Experiment  4.  I  immerfed  feveral  maggots  taken  out  of  hazel-nuts  in  brandy  :  thefe 
were  afterwards  inclofed  in  frefh  nuts  opened  for  their  reception,  and  placed  in  a  tempe- 
rature varying  from  70°  to  80°.  The  maggots,  which  had  been  confined  in  fpirit  for  a 
period  not  exceeding  17  hours,  revived  ;  but  when  the  time  of  immerfion  was  prolonged  to 
three,  or  even  two  day?,  every  atrempt  to  reftore  them  proved  fruitlefs. 

Having  now  flated  the  moft  flrikmg  fads  of  my  experiments  fully,  I  will  clofe  the  fub- 
jeft  by  forming  the  reft  into  a  table,  exprefling  the  number  of  infe£ls  of  each  kind  that 
have  been  killed  by  immerfion  in  wine,  brandy,  and  beer.  Thofe  marked  with  an  afterifk, 
being  fuch  as  delight  in  the  fliade,  were  fliut  up  in  perforated  chip  boxes  after  immerfion, 
and  placed  in  a  warm  temperature. 

*  The  maggot  of  the  filbert  will  remain  torpid,  but  not  deflroycd.  In  a  phial  of  brandy,  though  bottled  up 
'for  many  week?,    {Good on  the  Difeafes  xif  Prifons,  p.  174-) 

Name. 


Infers  itHmerfed  in  Fermented  Liqusi'S.^-Jeweller's  Foil.— Clue  for  Metals.       35  j 


Name. 

Wine. 

Brandy. 

Beer. 

Scarabseus  fimetarius,         -        .        » 

— . 

I 

__ 

Curculiones  Nucum  *,      -        -        - 

_. 

18 

.^ 

Grylli  domeftici  *,              -         - 
Erucx  Phalenarum,           -         -         - 

4 

2 
20 

I 

Panorpx  communes,          -         -         - 
Vefpa  vulgaris,         _         -         -         - 
Apes  meliificje,         -         _         -         - 

2 

2 

I 
I 

5 

Tipula  oleracea,       -         _         -         - 

— ■ 

I 

MM 

Mufcre  vomitorise,             «         -        . 

2 



— 

Mufcx  carnarise,       -         «         -         - 

4 

2 

I 

Mufcs  domeflicse,             _        -         - 

7 

5 

,^_ 

Tabani  decutientes,            -         -         - 

6 

4 

3 

Afilus  crabroniformis,        ■         _         - 

— - 

I 

Aranex  domefticK  *,        -         -         - 

4 

2 

6 

Onifci  Afelli  *,-.-- 

3 

2 

3 

Scolopcndrx  forficatse  *,            -         - 

I 

I 

2 

33 

63 

i(i 

JOHN  GOUGH. 


VLT. 

Various  Notices  refpeBing  the  PraBice  of  the  Arts  in  Turkey. — Jetueller's  Foil.— Gluey  or  MaJiiCf, 
for  Stones  and  Metals. — CajTuig  of  Malleable  Iron.— filtration  by  A/cent.  —Butter  preferved 
•without  Salt. — Extemporaneous  Teajl  *. 

T 

A  H  E  Armenian  jewellers  fet  precious  {tones,  particularly  diamonds,  to  much  advantage, 
with  a  foil,  which,  under  rofes  or  half  brilliants,  is  remarkably  beautiful,  and  is  not  fubje£b' 
to  tarnifli.  Their  method  is  as  follows  :  An  agate  is  cut,  and  highly  polifhed,  of  the  fliape 
defired ;  in  a  block  of  lead  is  formed  a  cavity  of  about  its  own  fize  ;  over  this  is  placed  a  bit 
of  tin,  of  the  thicknefs  of  ftrong  brown  paper,  fcraped  bright.  The  agate  is  then  placed  on 
the  tin  over  the  cavity,  and  ftruck  with  a  mallet.  The  beautiful  polifh  the  tin  receives  is 
foarcely  to  be  imagined.  This  is  in  general  kept  a  fecret,  and  fuch  foils  fell  for  half  and 
three  quarters  of  a  dollar  each. 

The  jewellers,  who  are  moflly  Armenians,  have  a  curious  method  of  ornamenting  watch-- 
cafes  and  fimilar  things,  with  diamonds  and  other  ftones,  by  limply  glueing  them  on. 

The  ftoneis  fet  in  filver  or  gold,,  and  the  lower  part  of  the  metal  made  flat,  or  to  corre- 
fpond  with  the  part  to  which  it  is  to  be  fixed  ;  it  is  then  warmed  gently,  and  the  glue  ap- 
plied, which  is  fo  very  ftrong  that  the  parts  never  feparate. 

This  glue,  which  may  be  applied  to  many  purpofes,  as  it  will  ftrongly  join  bits  of  glafs  or 
poliflied  fteel,  is  thus  made  : 

Diflblve  five  or  fix  bits  of  maftic  as  large  as  peas,  inasmuch  fpirit  of  wine  as  will' 
fuSice  to  render  it  liquid  j  in  another  veflel  diflblve  as  much  ifinglafs  (which  has  been 


•  Fxom  Eaton's  Survey  of  the  Turkijb  Empire,  oiSlavo.   London  179S* 


previouJI: 


356  Cojlitig  ef  Irott.-^Flltrntkn  ftji  AfcenU-^Prefei'vatkn  of  Buttef. 

previoufly  foaken  in  water  till  jt  is  fwollcn  and  foft)  in  French  brandy  or  rum,  as  will  make 
two  ounces  by  nieafure  of  (Irong  g'ue,  and  add  two  fmall  bits  of  gum  galbanum  or  ammo- 
niacum,  which  mud  be  rubbed  or  ground  till  they  are  diflblved }  then  mix  the  whole  with 
a  fuflicient  heat  5  keep  it  in  a  phial  Uopt,  and  when  it  is  to  be  ufed  fet  it  in  hot  water. 


A  remarkable  inftance  occurred  to  my  knowledge^of  an  individual  fa£t  which  might  Iiave 
been  of  the  utmoft  ufe  to  fociety,  but  which,  owing  to  the  ftate  of  knowledge  and  government 
in  Turkey,  was  wholly  loft  to  the  world.  An  Ar-tbian  at  Conftantinople  had  difcovered  the 
fecret  of  caftiog  iron,  which,  when  it  came  out  of  the  mould,  was  as  malleable  as  hammered 
iron.  Some  of  his  fabrication  M'as  accidentally  fhewn  to  Mr.  de  GafFron,  the  Pruffian  charge 
d'affaires,  and  Mr.  Franzaroli  (men  of  rnineralogical  fclence),  who  were  ftruck  with  the 
fa£t,  and  immediately  inftituted  an  enquiry  for  its  author.  This  man,  whofe'art  in  Chrif- 
tendom  would  have  infured  him  a  fplendid  fortune,  had  died  poor  and  unknown,  and  his 
iccret  had  periflied  with  him  !  His  utenfils  were  found,  and  feveral  pieces  of  his  cafting, 
all  perfe£tly  malleable.  Mr.  Franzaroli  analyfed  them,  and  found  that  there  was  no  ad- 
mixture of  any  other  metal.  Mr.  de  Gaffron  has  fince  been  made  fuperintcndant  of  the  iron 
manufa(n:ory  at  Spandai*,  where  he  has  in  vain  attempted  to  difcover  the  procefs  of  the 
Arabian. 


I  have  feen  pra£l:ifed  a  method  of  filtering  water  by  afcenfion,  which  is  much  fuperlor  to 
our  filtering  ftones  or  other  methods  by  defcent,  in  which  in  time  particles  of  the  ftone  or 
the  finer  fand  make  a  paflage  along  with  the  water. 

They  make  two  wells  from  five  to  ten  feet,  or  any  depth,  at  a  fmall  diftance,  which  have 
a  communication  at  bottom.  The  feparation  muft  be  of  clay  well  beaten,  or  of  other  fub- 
ftances  impervious  to  water.  The  two  wells  are  then  filled  with  fand  and  gravel.  The 
opening  of  that  into  which  the  water  to  be  filtered  is  to  run,  muft  be  fomewhat  higher  than 
that  into  which  the  water  is  to  afcend;  and  this  muft  not  have  fand  quite  up  to  its  brim, 
that  there  may  be  room  for  the  filtered  water,  or  it  may,  by  a  fpout,  run  into  a  veflel 
placed  for  that  purpofe.  The  greater  the  difference  is  between  the  height  of  the  two  wells, 
the  fafter  the  water  will  filter  ;  but  the  Icfs  it  is  the  better,  provided  a  fufficient  quantity 
of  water  be  fupplied  by  it. 

This  may  be  pra£lifed  in  a  cafk,  tub,  jar,  or  other  vefFel.  The  water  may  be  conveyed 
tc  the  bottom  by  a  pipe,  the  lower  end  having  a  fpunge  in  it,  or  the  pipe  may  be  filled  with 
coarfe  fand. 

It  is  evident  that  all  fuch  particles,  which  by  their  gravity  are  carried  down  by  filtration 
by  defcent,  will  not  rife  with  the  water  in  filtration  by  afcenfion.  This  might  be  pradifed 
on  board  (hips  at  little  expence. 


The  butter  which  is  moftly  ufed  in  Conftantinople  comes  from  the  Crim  and  the  Kubnn. 
They  do  not  faU  it,  but  melt  it  in  large  copper  pans  over  a  very  flow  fire,  and  fcum  off  what 
rifes;  it  will  then  preferve  fweet  a  long  time  if  the  butter  was  frefli  when  it  was  melted. 
We  preferve  butter  moftly  by  falting.  I  have  had  butter  which,  when  frefli,  was -melted  and 
fcummed  in  the  Tartan  manner,  and  then  falted  in  our  manner,  which  kept  two  years 

good 


Kx'temporaiieoia  Teaft. — Trarjlt  of  a  Cemst.  3J7 

■gfto'd  and  fine  taHed.  Wafliing  does  not  fo  effeflualiy  free  butter  from  the  curd  and  butter- 
milk, which  it  is  necefiary  to  do  in  order  to  preferve  it,  as  boiling  or  melting  ;  when  then 
fait  is  added  to  prevent  the  pure  butyrous  part  from  growing  rancid,  we  certainly  have  the 
he(t  procefs  for  prcfcrving  butter.  The  melting  or  boiling,  if  done  with  care,  does  not 
difcolour  ot  injure  the  tafte. 


The  prefervation  of  yea/l  having  been  a  fubjefl:  of  much  refcarch  in  this  country,  the 
following  particulars  may  perhaps  dcfcrve  attention: — On  the  coa  ft  of  Perfia  my  bread 
Was  maJe,  in  the  Englifn  manner,  of  good  wheat  flower,, and  with  the  yeafl;  generally  ufed 
there.  It  is  thus  prepared  :  Take  a  fmall  tea-cup  or  vvine-gU  fs  full  of  fplit  or  bruifed 
peafe,  pour  on  it  a  pint  of  boiling  water,  and  fet  the  whole  iii  a  veflcl  all  night  on  the 
hearth,  or  any  other  warm  place  ;  the  water  will  have  a  froth  on  its  top  next  mornings 
and  will  be  good  yeaft.  In  this  cold  climate,  efpecially  at  a  cold  feafon,  it  fliould  {land 
longer  to  ferment,  perhaps  tiventy-four  or  forty-eight  hours.  'I  he  above  quantity  made 
me  as  much  bread  as  two  fixpenny  loaves,  the  quality  of  -which  was  very  good  and  very 
light. 


VIII. 

Ohfervation  of  the  Pajpige  of  a  Comet  over  the  Di/k  of  the  Sun,     By  Citizen  DanGOS* 


o. 


°N  the  1 8th  of  January  1798,  Dangos  obferved  a  black,  round,  and  well  terminated 
tody,  which  crofled  the  difk  of  the  fun.  The  tirtie  of  Its  paflage  laded  20  minutes.  He 
thinks' it  could  be  nothing  but  a  comet.  He  tecolle£ls  having  obferved  a  Cmilar  phenome- 
non in  1784. 

Lalande  remarks,  that  Mercury  and  Venus  have  been  well  obferved  crofling  the  folit 
difk  in  the  form  of  black  fpots ;  but  that  comets  had  never  been  in  that  fituation  *. 

*  Tliis  notice,  which  is  taken  from  the  Journal  de  Phyfique  for  February  1798,  leaves  much  to  be  defiredk 
What  might  be  the  diameter  of  the  fpot;  whether  its  courfe  was  dircft  or  retrograde,  with  its  inclination  :o 
the  ecliptic,  or  to  the  folar  axis  ;  and  particularly  the  chord  it  defcribcd  ;  are  objefts  of  enquiry,  concerning 
which  we  fliall  probably  learn  more  in  future,  when  a  fuller  account  fliall  appear.  If  we  admit  that  it  was  a 
comet,  and,  by  way  of  obtaining  a  rough  notion  or  gCefs  of  its  diftance,  we  fuppofe  it  to  have  defcribed  a 
whole  diameter  of  the  fun,  we  fliall,  from  the  time  and  the  angular  fpace,  deduce,  that  it  was  about  feventy 
times  nearer  the  fun  than  our  planet.  This,  on  the  fuppofition  of  its  being  near  the  perihelion,  which  how- 
ever is  mere  fuppofition,  would  rank  it  among  thofe  comets  which  approach  the  neareft  to  that  luminary.  (See 
a  Table  of  the  elements  of  a  confiderable  number  of  comets  in  Pingie's  Cometographie,  which  is  copied  irtto 
Hutton'sDiftionary,  article  Comet.) 

If  we  confider  how  very  feldom  the  inferior  planets,  Venus  and  Mercury,  crofs  the  fun,  notwithftanding 
their  fliort  periods,  and  the  little  inclination  of  their  orbits,  it  will  be  lefs  furprifing  that  the  comets,  though' 
very  numerous,  ftiould  not  often  be  found  together  with  the  earth  in  the  line  of  their  nodes;  or  that  an 
unforefeen  etent,  of  fuch  fliort  duration,  fliouId  fcarcely  ever  meet  the  eye  of  the  aftronomcr.    N. 


Vol.  U.~NoY.  1798.  3  A  IX. 


55^  /nalyfis  of  the  Aqua-tHartne  or  Beryl, 

IX. 

Anahjts  of  the  Jqua-mnrine  or  Beryl ;  and  the  Difcovery  of  a  new  Earth  in  that  Stem, 
Read  bfore  the  French  National  IrflUute  it)  Pluviofey  in  the  Tear  VI,  (Feb,  14.  1798.) 
By  Citizen  VaV^ELIN  *. 

SeBlon  I.     JntrodtiBion. 

X  H  E  analyfis  of  minerals  is  one  of  thofe  operations  which  are  ufually  confidered  to  be- 
of  little  importance,  and  are  fubmitted,  by  cheniifts  of  the  firit  order,  as  unworthy  of 
their  care,  to  the  manipulation  of  their  pupils. 

I  am  wdl  aware  that  the  greater  number  of  analyfes  afford  refults  of  little  import- 
ance, which  do  not  repay  the  labour  and  the  time  bellowed  in  obtaining  them.  I  am 
likcwife  aware  that  thep<lo  not  offer  fo  brilliant  a  profpefl,  nor  promife  to  afford 
refults  of  fo  general  a  nature,  as  the  plan  of  operation  which  has  been  formed  with  regard 
to  fomc  of  the  mod  important  points  in  chemiflry.  But  I  am  not,  from  thefe  reafon's,  of 
opinion,  that  this  clafs  of  proccffes,  which  has  like  wife  its  difficulties,  and  requiies,  for 
its  fuccefsful  conduft,  a  certain  fcrics  of  reafoniiig,  and  particularly  an  exa£c  knowledge 
of  the  bodies  defcribed  ; — I  am  not  of  opinion  that  it  is  fo  little  entitled  to  engage  the  atten- 
tion of  philofophical  chemifts.  For  they  mull  recolle£l,  that  it  has  afforded  them  the  folid 
foundation  of  their  theories,  and  new  objefts  for  the  exercife  of  their  abilities. 

From  a  difregard  of  this  kind  it  was  that  Bergmann,  whofe  aflive  mind  could  not  fub- 
mit  to  the  details  of  experiment,  has  committed  fo  many  faults,  by  trufting  his  operations 
to  young  pupils,  who  had  not  acquired  the  habit  of  diftinguiflilng  new  fubftances  from  thofe 
■which  were  already  known. 

The  analyfis  of  the  beryl,  already  made  by  Bindheim,  M'ill  be  a  proof  of  what  I  here 
advance.     It  is  compofed,  according  to  him,  of  filex  64,  alumine  27,  lime  8,  and  iron  2. 

Citizen  Hauy  having  found  a  perfedl  agreement  between  the  ffrudlure,  hardnefs,  and 
weight  of  the  beryl  and  the  emerald,  engaged  me,  fome  months  ago,  to  compare  thefe 
two  ftones  by  chemical  means  alfo,  in  order  to  know  whether  they  were  compofed  of  the 
fcime  principles  in  fimilar  proportions. 

The  mod  interefting  circumilance  to  the  Inftitute  in  this  refult  being  a  new  earth, 
which  I  have  difcovered  in  the  beryl,  1  ftiall  pafs  llightly  over  the  other  objedls,  and  dweil 
more  particularly  on  its  dillinfllve  properties. 

ZeSlion  II.     The  Method  of  Analyfis, 

Experiment  I.  One  hundred  parts  of  beryl  reduced  to  fine  powder  were  fufcd  with 
300  parts  of  cauftic  potafli ;  the  raafs,  after  cooling,  was  diffufed  in  water,  and  treated 
with  the  muriatic  acid  :  by  this  means  the  folution  was  corripleted. 

The  muriatic  folution  was  evaporated  to  drynefs ;  towards  the  end  of  the  evaporation 
the  fluid  affumcd  the  form  of  a  jelly  :  the  dried  matter  was  then  diffufed  in  a  large  quantity-«f 
water.  Part  of  the  matter  was  diffolved  ;  but  a  white,  granulated  tranfparent  powder  re^ 
mained.  1  his  fubftance,  colletled  on  a  filter,  waflied  with  much  water,  and  dried  by 
ijgnition,  weighed  69  parts.     It  had  all  the  properties  of  filex. 

•  Axinales  de  Chimie,  xxvi.  155. 

Exptrimtni 


Dlfcovery  of  a  new  Eat'th.  359 

ExpL-riment  2.  The  fluid  feparated  from  the  filex  was  precipitated  by  the  carbonate  of 
potafli  of  commerce;  the  precipitate  coUefted  and  drained  was  treated  with  a  folution  of 
cauftic  potafli.  The  greateft  part  of  the  matter  was  diflblved  ;  but  there  remained  a  cer- 
tain quantity  of  earth  which  v/as  not  taken  up.  This  being  feparated,  vvalhed,  and  dried 
by  ignition,  was  of  a  brown  greyifli  colour ;  it  weighed  nine  parts.  In  thefe  nine  parts  it 
is  that  our  new  earth  is  contained.  We  fliall  fpealc  of  it  again  in  the  fubfequcnt  part  of 
this  Memoir. 

Experhnent  3.  The  alkaline  folution  of  the  foregoing  experiment  was  fuper-faturatcd 
with  muriatic  acid,  until  a  perfeft  folution  took  place,  and  thisw.^s  again  precipitated  by 
the  carbonate  of  potafli  of  commerce :  the  depofition,  wafhed  and  dried  by  a  red  heat, 
weighed  21  parts. 

This  fubflance  appeared  to  me  at  that  time  to  be  pure  alumine.  We  fliall  fee  wh.it 
conclufion  ought  to  be  made,  after  examining  the  properties  of  the  new  earth  which  I 
Iiave  announced. 

Experiment  4.  The  nine  parts  in  Experiment  2.  remaining  after  the  adlion  of  the  potafli, 
and  in  which  I  announced  the  exiftence  of  a  new  earth,  were  diflblved  in  the  nitric  acid  } 
the  folution  was  evaporated  to  drynefs,  and  the  refidue  again  diflblved  in  water.  The  fo- 
lution of  this  fubfliance  having  aflumed  a  reddifli  yellow  colour,  which  indicated  the  pre- 
fence  of  iron,  a  folution  of  the  hydro-fulphuret  of  potafli  was  mixed  with  it ;  a  black  volu- 
minous precipitate  was  formed  ;  the  fluid  was  heated  in  order  to  favour  the  union  of  the 
parts,  after  which  the  fluid  was  decanted  clear  and  colourlefs.  The  black  precipitate  by 
calcination  became  of  a  red  brown  colour,  and  weighed  one  part.  When  diflblved  in  the 
muriatic  acid,  and  the  folution  evaporated  to  drynefs,  it  afforded  a  beautiful  blue  when  an 
atom  of  the  matter  was  thrown  into  a  folution  of  the  PruflTiate  of  potafli  :  it  was  therefore 
the  oxide  of  iron. 

The  fluid  from  which  this  exide  had  been  feparated  was  again  evaporated  to  drynefs ; 
and  though  at  firfl:  it  had  no  colour,  it  ncverthelefs  became  red  towards  the  end  of  the  pro- 
cefs,  and  the  refidue  preferved  that  colour.  This  refidue  having  been  left  for  24  hours  in 
a  capfule,  became  reduced  into  a  kind  of  gelatinous  fluid,  of  a  yellowifli  red  colour  :  cold 
water  poured  thereon  diflblved  the  whole  mafs ;  but  the  folution  was  red  and  turbid :  by 
«xpofure  on  the  heated  fand-bath,  red  flocks  were  feparated,  and  the  fluid  became  as  clear 
as  water.  Thefe  flocks,  carefully  feparated,  waflied  and  dried,  weighed  half  a  part :  it 
was  alfo  the  oxide  of  iron  j  which,  with  the  part  before  obtained  by  means  of  the  hydro- 
fulphuret  of  potafli,  makes  one  part  and  a  half  of  that  fubfl:ance. 

Experiment  5.  The  earth  being  thus  perfedly  deprived  of  the  oxide  of  iron,  I  feparated 
It  from  the  nitric  acid  by  means  of  the  common  carbonate  of  potafli ;  and  I  obtained  12 
parts  of  a  white  earth,  foft  beneath  the  fingers,  and  foluble  in  acids  with  eflbrvefcence. 

We  fee  that  this  earth,  in  its  feparation  from  the  nitric  acid,  did  abforb  four  parts  and  a 
half  of  carbonic  acid  i  fince  out  of  nine  which  were  fubjefted  to  experiment,  one  and  a 
half  of  the  oxide  of  iron  were  obtained  ;  which  leaves  7,5  for  the  earth  contained  in  the 
J  2  parts  of  carbonate  lafl;  precipitated. 


3  A  4  StSHsn 


360  Propertks  and  Habitudes  of  ihe  tuiv  Earth  difcovered  in  the  Beryf, 

SeSion  III.     Expofttion  of  the  Properties  of  the  new  Earth  contained  in  the  Beryl, 

Experiment  i.  The  12  parts  of  earth  united  with  carbonic  acid,  as  before  mentioned^ 
were  put  into  fulphuric  acid,  which  diflblved  them  completely  with  efFervefcence.  The 
folution  had  a  very  facchavine  tafle  at  firft,  and  aftringent  at  laft.  The  folution  left  till 
the  following  day  afforded  irregular  cryllals,  very  folid  and  Hiccharine  like  the  folution. 
which  afforded  tliem. 

Experiment  2.  Thefe  cryflals  were  again  diffolved  in  water  ;  the  folution  rrixed  with  ful- 
phate  of  potafli  did  not  afford  alum  either  immediately  nor  by  evaporation,  as  happens  in- 
the  alumine  when  combined  with  the  fulphuric  acid.  Each  of  thefe  falts  cryflallizes  fe- 
jsafately,  without  contraifling  any  union. 

I  repeated  tliis  operation  five  times  in  fucceffion,  with  different  dofes  of  fulphate  of  poN 
afh,  without  obtaining  more  fuccefs  than  at  firft.  At  laft,  to  convince  myfclf  of  the  differ- 
ence between  this  earth  and  alumine,  I  took  equal  quantities  of  the  one  and  the  other  ; 
and  after  having  diffolved  them  in  the  fulphuric  acid,  I  mixed  them  with  Kke  quantities  of- 
fulphate  of  potafli.  I  conftantly  obtained  oftahedral  alum  with  the  aiumine  ;  but  the 
earth  of  the  beryl  afforded  only  an  irregular  fait. 

Thefe  differences  firft  difcovered  between  the  two  earths,  induced  rae  to  feek  for  others,. 
by  comparing  them  in  a  greater  number  of  points.  ' 

,  SeBion  IF.    Campari/on  of  ihe  Properties  of  the  Earth  of  Beryl  uith  thofe  of  Aiumine. 

Experiment  I.  For  this  purpofc,  I  feparately  diffolved  equal  quantities  of  alumine  and  of 
tlie  earth  of  beryl  in  nitric  acid,  to  perfect  faturation. 

The  fait  which  atofe  from  the  combination  of  the  earth  of  beryl' with  the  nitric  acid,  did: 
not  appear  fufccptible  of  cryftallization ;  it  ftrongly  retains  moifture ;  by  deficcation  it- 
becomes  converted  into  a  kind  of  ductile  pafte,  which,  when  expofed  to  the  air,  power- 
fully attradls  moifture.     Its  tafte  is  at  firft  very  fweet,  and  afterwards  aftringent. 

Experiment  2.  The  nitrate  of  alumine  likewife  cryftallizes  with  confiderable  difficulty  5 
but  it  does  not  attra£l  moifture  fo  ftrongly.  Its  tafte  is  not  faceharine,  like  that  of  tha 
nitrate  formed  with  the  earth  of  beryl. 

I  made  the  following  comparative  effays  of  the  folutions  of  thefe  two  falts,  uGng  equal 
quantities  of  each. 

I.  The  nitrate  of  alumine,  mixed  with  a  folution  of  nut-galls  in  alcohol,  afforded  no  pre- 
cipitate. The  fluid  fimply  acquired  a  flight  greenifti  colour,  and  loft  fomewhat  of  its 
tranfparence  ;  however,  at  the  expiration  of  fome  hours,  the  fluid,  having  been  diluted 
with  water,  let  fall  a  greyifti  precipitate. — 2.  The  fait  of  the  earth  of  beryl,  mixed  with 
the  fame  re-agent,  immediately  afforded  a  depofition  in  flocks  of  a  yellow  brown  colour. 

3.  The  nitrate  of  alumine,  mixed  with  the  oxalate  of  potafti,  immediately  afforded  a  pre- 
cipitate in  the  form  of  very  abundant  white  flocks,  which  fubfided  to  the  lower  part  of  the 
veflel,  and  left  the  fuperior  fluid  perfedly  clear.— 4.  The  fait  of  the  earth  of  beryl,  with- 
the  fame  re-agent,  did  not  afford  the  flighteft  appearance  of  a  precipitate,  eycn  after  feve- 
i*i  days. 

5.  The 


Propirt'ies  and  Hahltudet  of  the  tiew  Earth  contained  in  the  Beryl.  361 

5.  The  nitrate  of  alumine,  mixed  with  tartrite  of  potafh,  immediately  formed  a  depoff- 
tion  m  flocks,  and  the  fuper-natant  liquor  became  clear  and  colourlefs. — 6.  The  fait  of  the 
earth  of  beryl,  with  the  fame  re-agent,  did  not  produce  any  fign  of  precipitation  after  feve- 
rnl  days. 

7.  The- nitrate  of  alumine,  mixed  with  a  folution  of  the  phofphate  of  foda,  afforded  a 
gelatinous  femi-tranfparent  precipitate,  which  fubfided  very  flowly. — 8.  The  fait  of  the 
earth  of  beryl  alfo  formed  a  precipitate  with  the  fame  re-agent ;  but  it  was  lefs  gelatinous,, 
a«d  lefs  tranfparent,  and  it  alfo  fell  down  more  fpeedily. 

9.  The  nitrate  of  alumine,  mixed  with  very  pure  Pruihate  of  potafli,  inftantly  afforded  a 
very  abundant  whitifli  precipitate,  which  becama  green  at  the  end  of  a  few  hours. — 10. 
The  fait  of  the  earth  of  beryl,  with  the  fame  re-agent,  afforded  no  precipitate,  even  after 
feveral  days.  ■ 

II.  Th.e  nitrate  of  alumine,  mixed  with  a  faturated  folution  of  potafli,  afforded  a  gelati- 
nous magma,  which  was  femi-tranfparent,  and  foon  becajne  filled  with  numerous  bubbles 
of  gas,  which  raifed  it  to  the  upper  part  of  the  fluid. — 12.  The  fait  of  the  earth  of  beryl, 
mixed  with  the  fame  re-agent,  afforded  a  precipitate  in  flocks,  which  was  not  filled  with- 
bubbles  like  the  foregoing,  and  which  fell  to  the  bottom  of  the  liquid. 

13.  The  nitrate  of  alumine,  mixed  with  a  fokition  of  cauflic  potafli,  at  firfl  afforded  a 
gelatinous  depofition,  which  was  afterwards  taken  up  by  the  excefs  of  alkali. — 14.  The  fait 
of  the  earth  of  beryl,  treated  with  the  fame  re-agent,  was  affetled  in  the  fame  manner,  ex- 
cepting only  that  a  larger  quantity  of  alkali  was  required  for  the  fecond  folution. 

15.  The  nitrate  of  alumine,  mixed  with  a  folution  of  carbonate  of  ammoniac,  formed  a 
precipitate  which  was  not  rediffolved  by  an  excefs  of  alkali. — 16.  The  fait  of  the  earth  of 
beryl,  mixed  with  the  fame  re-agent,  afforded  a  precipitate  which  was  entirely  re-diffolve'd 
by  an  excefs  of  alkali. 

We  fee  by  moft  of  thefe  experiments,  that  the  earth  of  beryl  effentially  differs  from  alu- 
mine, which  however  it  refembles  much  more  than  any  other  earth,  and  with  which  it  may 
even  be  eafily  confounded  in  certain  refpe£ls. 

But  the  experiment  which  induced  me  to  fix  my  opinion  irrevocably  with  refpecl  to  this- 
earth,  was  that  which  fliewed  the  comparative  degree  of  attraclion  of  the  two  earths  for  the 
fame  acid. 

To  acquire  this  knowledge,  I  diffolved  in  the  nitric  acid  twelve  parts  of  very  pure  alu- 
mine, and  evaporated  to  drynefs,  in  order  to  expel  the  furplus  of  acid  which  was  in  the 
fluid.  The  refidue  being  diflblved  in  water,  I  added  to  the  folution  ten  parts  of  the  earth 
of  beryl,  recently  precipitated  from  its  folvent,  well  wafhed,  and  (till  moift. 

I  added  no  more  than  ten  parts  of  the  earth  of  beryl,  to  precipitate  the  twelve  parts  of 
alumine,  th(jugh  I  had  afcertained,  by  other  experiments,  that  a  fomewhat  greater  quantity 
ef  the  earth  of  beryl  than  of  alumine  was  neceffary  to  faturate  the  fame  quantity  of  acid  ; 
but  I  chofe  rather  that  a  fmall  quantity  of  alumine  fhould  remain  in  folution,  than  that 
any  portion  of  the  earth  of  beryl  fliould  mix  with  the  precipitate.  When  therefore  the 
mixture  had  thus  been  made,  I  boiled  the  fluid  for  a  quarter  of  an  hour,  then  filtered  it,  and 
retained  on  the  filter  the  earthy  precipitate.  After  wafliing  this,  I  combined  it  with  the  ful- 
pauric  acid,  and  evaporated  to  drynefs,  in  order  to  expel  the  excefs  of  acid  j  after  which, 

rerdiffohinS- 


j52  Coinpofifin  of  Alunnne  and  the  new  Earth  in  the  Beryl. 

re-diflblving  it  In  water,  I  added  a  few  drops  of  fulphatc  of  pot-afli  to  the  folutlon,  and  ob- 
tained o£lahedral  cryibls  of  alum. 

Now  it  is  evident  that  the  earth  of  beryl  has  more  affinity  with  the  nitric  acid  than  alu- 
mine  has,  and  confequently  that  it  is  not  the  fame  earth.  If  the  earth  of  beryl  be  not  alu- 
mine,  there  is  much  greater  reafon  to  decide,  that  it  is  not  one  of  the  other  known  earths  ; 
for  it  differs  much  more  from  them  than  from  alumine.  I  therefore  confider  this  earth  as  rt 
vew  fubftance,  different  from  all  thofe  we  are  yet  acquainted  with.  It  is  true,  that  it  in 
fome  meafure  refembles  a'.umine,  namely,  in  its  foftnefs  to  the  touch,  its  adhefion  to  the 
tongue,  its  levity,  its  folubility  in  pot-afh,  and  its  precipitation  from  its  folutions  by 
ammoniac.  But  it  differs  from  alumine  in  its  other  properties.  Its  combinations  with 
acids  have  a  very  faccharine  tafle  ;  it  has  a  flronger  afEnity  with  thcfe  foivenrs ;  it  does  not 
afford  alum  with  the  fulphuric  acid  and  potafli ;  it  is  totally  foluble  in  carbonate  of  ammo- 
niac -,  and  laflly,  it  is  not,  like  alumine,  precipitable  from  its  folutions  by  the  oxalate  and 
the  tartrite  of  pot-afli. 

This  earth  being  foluble  in  cauftic  pot-afli,  like  alumine,  we  can  no  longer  trufl:  to  this 
(imple  charafter  to  afcertain  the  prefence  of  the  latter  earth  ;  for  it  m*ay  happen  that  the 
eanh  of  beryl  fliould  be  taken  for  alumine,  or  a  mixture  of  both  for  one  or  the  other  of 
thefe  pure  earths.  It  will  therefore  be  necefiary,  whenever  an  earth  foluble  in  pot-afli  is 
found,  to  endeavour  to  convert  it  into  alum  by  the  known  methods.  If  it  do  not  afford 
alum,  it  may  be  certainly  concluded  that  it  is  not  alumine.  But  it  may  poffibly  afford 
alum,  and  neverthelefs  contain  the  earth  of  beryl  j  a  mother  water  will  then  remain,  in 
■which  this  laft  earth  will  be  fufpendcd. 

To  feparatc  the  fmall  quantity  of  alum,  which  likcwife  remains  in  this  mother  water, 
It  will  be  proper  to  decompofe  it  by  a  folution  of  the  carbonate  of  ammoniac  added  in  ex- 
eefs  ;  by  .this  means  alum  will  be  entirely  precipitated,  and  the  earth  of  beryl  will  remain 
diffolved  in  the  carbonate  of  ammoniac.  This  earth  may  afterwards  be  readily  feparated 
by  boiling  the  folution  for  a  certain  time.  The  heat  will  drive  off  the  carbonate  of  ammo- 
niac, and  the  earth  will  fall  down  in  the  form  of  a  powder. 
•  '  By  comparing  the  refults  of  the  analyfis  of  the  beryl  with  thofe  which  Klaproth  and  my- 
felf  obtained  from  that  of  the  emerald,  we  might  conclude,  that  thefe  two  ftones  are  very 
different  from  each  other  ;  for  I  found  that  the  emerald  was  compofed  of  64  of  filex,  29 
alumine,  2  lime,  between  3  and  4  of  the  oxide  of  chrome  *,  and  i  or  2  of  water ; 
whereas  the  beryl  is  compofed  of  69  filex,  21  alumine,  8  of  the  peculiar  earth,  and  ij  of 
the  oxide  of  iron. 

But  fince  that  time  I  have  found  that  the  emerald  likewife  contains  this  new  earthy 
whence  it  follows,  that  the  emerald  and  the  beryl  are  one  and  the  fame  fubftance,  differing 
only  in  their  colouring  matter. 

With  regard  to  the  proportion  in  which  I  have  obtained  this  earth  of  the  beryl,  I  do  not 
give  it  as  ftriftly  accurate  ;  for  it  is  poffible  that  part  may  have  been  diffolved  at  the  fame 
time  as  the  alumine  by  the  pot-afh  f . 

•  This  it  the  metallic  acid  difcovered  in  the  red-lead  of  Siberia,  of  which  a  (hort  account  was  given  in  our 
Journal,  II,  145.     The  memoir  gt  length,  with  additional  infonnation,  will  appear  in  our  next.      N. 

f  Since  the  above  was  written,  I  have  afcertained,  that  there  was  in  fact  a  certain  quantity  of  the  earth  of 
tcryl  diffolved  by  the  pot-afh  with  tlic  alumine;  and  that  inftead  of  i  per  cent,  the  beryl  contains  16. 

1  have 


New  detached  Efcapemeni.  363 

I  have  not  yet  thought  it  proper  to  give  a  name  to  this  earth.  I  (hall  wait  till  its  pro- 
perties are  better  Icnovvn  •,  befides  which,  i  fhoukl  be  glad  to  have  the  advice  of  my  brother- 
chemifts  on  the  fubjc£l  *. 

In  a  fecond  memoir,  I  fliall  fpeedily  give  the  moft  complete  account  in  my  power,  of  its 
combhiarions  with  the  acids  and  feme  of  the  combultible  bodies  |. 


F. 


X. 

Defcription  of  a    mwiiiveHied  deiached  Efcatetnent  for  Poclet  Watches^     is'c. 

By  Mr.  John  Prior  %. 


I  G.  I  and  2,  Plate  XV,  reprefent  the  principal  parts  of  the  efcapement. 

Fig.  I.  A  B,  the  pillar-plate  ;  and  A  B  E  F,  fig.  2,  is  a  feftion  of  the  frame  without 
pillars  or  potance.  C,  the  cock  fcrewed  to  the  potance- plate  at  D.  G,  the  balance,  the 
lower  part  of  which  runs  in  the  plate  (but  perhaps  a  potance  will  be  more  convenient  for  it 
in  a  pocket  watch).  H,  the  regulating  fpring,  pinned  faft  in  the  ftud  at  I.  O,  the  friiflion 
wheel.  N,  its  arbor,  the  higlier  pivot  of  which  runs  in  the  collet  the  balance  is  rivetted  to, 
and  the  lower  in  a  collet  fcrewed  faft  on  the  balance- arbor  at  P;  fo,  when  the  balance 
turns  round,  the  fri6lion-wheel  is  taken  along  with  it. 

M,  the  intermittent  lever-wheel.  L,  its  arbor.  R,  its  pinion,  in  the  rim  of  which  wheel 
are  put  an  equal  number  of  pins  on  each  fide.  The  pins  on  one  fide  of  the  wheel  are  put 
exa<?lly  at  the  middle  didance  of  thofe  on  the  other  fide. 

T,  the  intermittent  lever,  fcrewed  faft  to  K,  its  arbor.     QJ5.are  its  banking  fcrews. 

The  lever  is  all  made  of  one  folid  piece  of  fteel.  That  end  of  it  next  the  wheel  Is  cut 
open  wide  enough  to  receive  the  rim,  without  touching  either  fide  of  it,  as  far  as  the  pal- 
lets or  inclined  planes  are  ;  at  the  end  of  which  it  is  cut  wider,  to  admit  the  pins  of  the 
wheel.     {Stcfg.  2,  a  fe£l;ion  of  it  as  under  L.) 

The  diftance  from  the  centre  of  the  balance  to  the  extreme  part  of  the  lever,  or  end  of 
the  pallets,  is  divided  in  a  right  line  into  ten  equal  parts,  and  the  pivot-hole  of  the  fridlion- 
wheel  is  made  at  the  firft  tenth  divifion  from  the  centre  of  the  balance.  There  are  thirteen 
femi-diameters  of  the  friclion  wheel  from  its  centre  to  the  end  of  the  pallets. 

When  the  balance  Is  at  reft,  then  the  centre  of  the  balance,  the  centre  of  the  frldtion- 
\vheel,'and  the  centre  of  the  lever,  will  be  all  in  one  right  line.     (Seey?g-.  i.) 

The  lever  is  divided  into  three  equal  parts.     The  diftance  from  the  end  of  the  pallets  to 

•  The  moft  cliarafteriftic  property  of  this  earth,  confirmed  by  the  lateft  experiments  of  our  colleague,  being, 
that  it  forms  falls  of  a  faccharine  tafte,  we  propofe  to  call  it  Glucine,  from  y'Kvx.vq  fwccf,  yi^xu  fwcet  wine,. 
yXiwana  to  render  fweet.  This  denomination  will  befignilicant  enough  to  afiift  the  memory  ;  it  docs  not  derive  , 
its  etymology  from  a  fcnfe  too  ftriftly  dctermiaed  ;  neither  does  it  prefent  ideas  falftly  exclufive,  like  thofe 
name*  which  might  be  taken  from  the  name  of  the  ftone  which  afforded  the  firft  fpEcimen  of  the  new  fiibftance, 
the  name  of  the  firft  village  where  it  was  met  with,  &c.  &;c.  Thefe,  we  apprehend,  are  the  true  principles  for 
the  advancement  of  fcience,  and  facilitating  its  ftudy,  by  means  of  nomenclature.  Note  of  the  Editors  of  the 
Annales. 

i-  Cit.  Vauquelin  has  publilhed  an  appendix  to  this  paper,  on  the  general  properties  of  this  earth,  which  wiii 
appear  in  our  next.     N. 

%  Tranfaftions  of  the  Society  for  the  Encouragement  of  Arts,  1758.     A  premium  of  thirty  guineas  was 
given  to  the  inventor.    N. 

the 


364  ■W''?"'  Efiopemeni. — PiJIctis  enilr-ely  MetaUli:. 

the  centre  of  motion  of  the  lever,  one  part  \  and  from  the  centre  of  motion  to  the  centre  oF 
the  fri£lion-wheel,  when  the  bahmce  is  at  reft,  two  parts  :  fo  that,  whatever  the  velocitjr 
may  be  at  the  end  of  the  pallets  when  in  motion,  that  part  of  the  lever,  or  the  forked  part  of 
U,  which  is  oppofite  the  centre  of  motion  of  the  fridlion-whecl,  will  be  twice  as  much. 

S  S  reprefents  a  fuperficial  view  of  the  pallets.  The  pallet  below  the  pillar-plate  is  taken 
ofFfrom  the  other,  otherwife  the  place  of  aflion  could  not  be  feen  in  the  drawing. 

In  Jig.  I,  we  have  a  view  of  the  lever  before  the  machine  is  wound  up  :  a  pin  is  half-«'ay 
down  the  pallet ;  but  when  the  pin  impels  the  pallet,  the  lever  moves,  and  gives  motion  to 
the  balance,  and  the  pin  is  difengaged  from  the  pallet  at  the  angle  :  that  inllant  a  pin,  on 
the  oppofite  fide  of  the  wheel,  falls  upon  a  circular  part  of  the  end  of  the  other  pallet,  or 
upon  that  part  where  it  and  the  lever  are  entirely  at  reft,  until  the  balance  makes  its  return, 
r.nd  the  friftion-wheel  comes  into  the  forked  end  of  the  lever.  Then  the  friftion-wheel 
Impels  the  lever,  while  the  balance  runs  over  the  fpace  of  about  one  hundred  degrees. 
Tlien  the  pin  drops  off  at  the  end  of  the  pallets  as  before,  and  the  balance  is  entirely  kft  at 
liberty  ;  at  which  time  its  velocity  is  lb  great,  and  its  motion  fo  eafy,  that  it  turns  once  round 
upon  its  pivots,  and  two  hundred  and  forty  degrees  every  vibration. 

It  is  to  be  obfcrved,  that,  in  the  ends  of  the  fork,  one  part  is  turned  up  and  the  other  down, 
in  order  they  may  not  both  go  through  one  notch  in  the  balance  arbor  j  for,  by  having  two 
different  parts  cut  away,  the  fork  is  locked  faft  in  every  vibration,  and  is  unlocked  only  by 
the  fri£lion-wheel  in  its  return  for  another  vibration. 

Notwithftanding  the  balance  makes  one  turn  and  two  hundred  and  forty  degrees  every 
vibration  around  its  axis,  yet,  when  the  balance  is  at  reft,  and  the  fame  power  applied  to 
it  (which  keeps  it  in  motion  as  above),  the  balance  will  only  move  through  the  fpace  of 
about  fifteen  degrees,  which  is  only  one  fortieth  part  It  keeps  it  up  to  when  in  motion. 

It  muft  be  allowed,  the  lefs  the  wheels,  or  the  power,  have  to  do  with  the  balance,  the 
more  accurate  the  time  will  be  fliewn  *, 


XI. 

On   Mr.  CARTWSIGHr's  Inveniwii  for  rendering  the  Pijlons  of  Steam  Engines,  Pumps,  and 
ether  Hydraulic  apparatus  tight  by  metallic  Parts,  ivithoiit  packing  or  leathering.    (W.  N.) 

To  Mr.  NICHOLSON. 

SIR,  Richmond,  Oft.  10.  175S. 


I 


HAVE  lately  been  informed,  that  a  new  method  of  packing  fteam  engines  has  been  in- 
vented by  a  Mr.  Cartwright,  which  is  faid  to  be  particularly  advantageous  in  faving  fri£lion 
and  refifting  an  heavy  column  of  water  in  pumps.  I  (hall  be  very  glad  to  fee  a  defcription 
of  the  fame  in  your  Journal,  with  your  opinion  of  its  effe£ls,  &c. 

Your  conftant  Reader, 

A.R. 

*  Artifts  will  perceive  that  this  is  an  improvement  of  the  anchor  fcapementof  Mudge,ofwhich  the  inventor 
was  not  aware  till  he  came  to  London.  In  this  the  pallets  cxaftly  refemble  thofe  of  Graham's  dead  beat  (Philof. 
Journal,  II.  51.  ),  and  a  tail  afts  againft  two  planes  in  the  axis  of  the  balance.  Pallets  like  thofe  of  Mr.  Prior 
were  adapted  to  a  long  pendulum  by  Mr.  Crofthwaite  of  Dublin,  in  the  year  J7SS,  (Memoirs  of  the  Irifh 
Acad,  vol,  II.)  and  fince  that  time  alfoby  other  perfons  in  Lohdon,    N. 

THE 


Defer ipl'ton  9/ a  pttU  Tljion  nvilh  metallic  Fiititigt.  3 55 

•THE  contrivance  to  which  my  correfpondent  refers,  13  part  of  a  fteam  engine,  for  which 
H  patent  has  been  taken  out.  It  is  generally  undcrftood  that  in  pra£lice  it  is  neceflary  to' 
apply  the  pacicing  clofe  round  the  pillon  of  a  (team  engine,  in  fuch  a  manner  as  to  maice  it 
aft  (Irongly  againfl;  the  fides  of  the  Cylinder,  which  mult  occafion  a  confiderable  degree  of 
friction  :  and  when  it  has  worlced  loofc,  it  may  be  concluded  that  fome  lofs  of  force  muft 
follow,  from  the  efcape  of  elaftic  fluid  between  the  furfaces  intended  to  be  in  contadh  A 
fimilar  obfervation  may  be  applied  to  the  ufual  leathering  of  pumps,  in  which  the  fri£lion 
is  rery  great,  and  the  refiflance  to  fevere  prefijre  very  far  from  being  eftedlual.  Early  in  the 
prcfent  century,  a  contrivance  was  made  by  a  Mr.  Ilalkins  to  prevent  fridion,  by  fubilitut- 
ing  quickfilver  Inftead  of  leather  ;  which,  for  fcvcral  ftatical  reafons,  and  alfo,  as  I  fufpedl, 
from  fome  of  a  chemical  nature,  could  not  be  brought  into  general  ufe.  The  reader  may 
fee  a  very  full  defcription  of  this  engine,  in  Defaguliers's  Courfe  of  Experimental  Philofo- 
phy,  II.  491. 

Mr.  Cartwright's  invention  confids  in  ufing  folid  mafles  of  metal  inftead  of  the  packing 
or  leathering  ;  which,  by  means  of  fprings,  adapt  themfelves  to  the  variations  of  diameter  in 
the  cylinder,  and,  by  their  mode  of  application  above  each  other,  are  expected  to  prevent 
that  efcape  of  fluid  which  would  clfe  take  place  through  the  intervals  between  the  feveral 
pieces.  Imagine  the  pillon  to  confift  of  a  circular  plate  of  metal,  nearly  equal  in  diameter 
to  the  cylinder  in  which  it  is  to  move.  It  will  make  no  difference  in  the  general  confide- 
ration  of  our  fubjeft,  whether  this  pifton  have  a  valve  in  it  or  not.  Upon  the  upper  furface 
of  this  pifton  are  laid  three  or  more  pieces  of  metal,  which  all  together  compofe  a  flat  cir- 
cular ring  ;  the  ends  of  the  feveral  pieces  nearly  touching  each  other.  A  very  moderate 
portion  of  mechanical  knowledge  will  fuggefl  the  manner  in  which  thefe  pieces  might  be 
made  to  recede  outwards,  by  means  of  fprings;  fo  as  to  occupy  the  circumference  of  a  greater 
circle  externally,  than  that  to  which  they  would  nearly  correfpond  when  regularly  prefled 
inwards.  If  the  pifton  in  this  fituation  be  placed  in  its  cylinder,  it  is  evident,  that  the 
pieces  compofing  the  ring  will  be  forced  againft  the  concavity ;  which,  if  of  the  proper  cur- 
vature, they  will  fit,  and  prevent  any  fluid  from  pafllng  through,  except  at  the  interftices, 
where  the  ring  is  rendered  incomplete  by  being  divided  into  parts.  To  remedy  this,  a 
fecond  ring  is  laid  upon  the  firft,  with  its  joints  half-way  between  the  joints  of  the  former, 
in  the  fame  manner  as  we  every  day  obferve  in  courfes  of  brick-work.  This  fecond  ring, 
being  urged  outwards  like  the  firft,  performs  the  fame  function  ;  but  any  fluid  that  may 
pafs  downwards  through  the  interftices  of  the  upper  ring,  will  be  ftopped  by  the  conti- 
guous parts  of  the  lower  ;  and,  on  the  contrary,  whatever  fluid  may  pafs  upwards  through 
the  interftices  of  the  lower  ring  will,  for  the  fame  reafon,  be  ftopped  by  the  upper. 

From  this  defcription  it  is  fufiiciently  clear,  that  Mr.  Cartwright  is  entitled  to  much 
praife  for  the  ingenuity  and  acutenefs  difplayed  in  his  contrivance.  The  practical  value 
of  that  contrivance,' refpefting  which  I  am  requefted  to  ftate  the  fads,  will  probably  be  af- 
certained  from  the  following  confiderations : 

In  the  ufual  ftuflSng  or  leathering,  the  elafticity  of  the  organized  matter  made  ufe  of  i« 
fuppofed  to  a£t,  in  each  individual  part,  fo  far  independently,  that,  if  there  be  an  irregularity 
in  the  cylinder  by  variation  of  its  curvature  or  magnitude,  this  irregularity  will  be  followed 
«p  and  fitted  ty  the  elaftic  material.  But  Mr.  Cartwright's  metallic  packing  pofleflfing  a 
determinate  curvature,  will  fit  only  when  the  zone  witii  which  it  i»  in  contad  poflefles  the 
Voi.,11.— Nov,  1798.  3B  ^  fame 


366  Eicaminatkn  of  a  new  Pijott  •with  metallic  Fittings. 

fame  curvatufe.  If  his  pifton  be  prefled  into  a  fmaller  cylinder  than  correfponds  with  the 
a£lual  circle  his  pieces  are  adapted  to  form,  thofe  pieces  will  be  prefled  in,  and  will  touch 
only  at  their  extremities  ;  fo  that  every  joint  will  be  immediately  over  a  place  where  the 
oppofite  ring  does  not  in  f aft  touch  the  cylinder  :  it  will  therefore,'  in  this  cafe,  leak  prin- 
cipally at  the  joints.  And,  on  the  contrary,  if  his  pifton  be  prefled  into  a  larger  cylinder 
than  correfponds  with  the  circle  of  the  rings,  each  portion  of  thofe  rings  will  touch  the 
cylinder  in  one  point  only.  The  moft  favourable  point  will  be  at  the  half-way  between  the 
extremities  of  each  piece.  In  this  pofition  the  joints  indeed  will  not  leak,  but  every  other 
part  of  the  circumference  will;  and  the  places  of  the  moft  open  paflage  will  be  at  thofe 
points  of  the  circumference  which  are  equidlftant  between  joint  and  joint.  Thefe  confide- 
rations  relate  to  perfect  circles  ;  but  if  we  attend  to  fmaller  irregularities,  whether  convex- 
ities or  concavities  in  the  cylinder,  it  appears  evident,  that  the  fegments  of  the  rings  being 
inflexible  will  ftill  lefs  efFe£tually  adapt  themfelvesto  fuch  imperfections. 

Thefe  objeftions,  relating  to  the  figure  of  the  periphery  of  this  metallic  pifton,  are  of 
very  ferious  import :  thofe  which  relate  to  its  action  are  fcarcely  lefs  fo.  The  furfaces  of 
the  rings  thus  laid  upon  the  pifton  and  upon  each  other,  together  with  the  furface  of  the 
piece  which  confines  them  from  rlfing,  muft  all  be  very  well  adapted  to  each  other ;  and 
the  number  of  fquare  inches  of  this  furface  muft,  in  the  nature  of  the  contrivance,  be  con- 
fiderable  enough  to  afford  much  fri£tion.  It  may  reafonably  be  doubted  whether  thefe 
pieces,  in  the  rapidity  of  afcent  and  defcent,  can  obey  the  a£tion  of  the  fprings  during  the 
very  fhort  times  in  which  the  pieces  are  oppofed  to  the  irregularities  they  are  meant  to 
remedy.  But  when  a  great  preflure,  fuch,  for  example,  as  the  readlion  of  a  column  of- 
100  feet  of  water,  comes  to  be  exerted  upon  the  face  of  this  apparatus,  the  plates  or  pieces 
of  thefe  rings  may  be  imagined  to  be  confined  in  a  vice.  The  preflure  of  fuch  a  column  will- 
amount  to  more  than  40  pounds  upon  every  fquare  inch.  Whence  we  may  conclude, 
ieither  that  they  would  not  move  at  all,  or  that  the  force  of  the  fprings  muft  be  fuch  as 
greatly  to  load  the  work  with  fri£tion,  and  damage  the  apparatus  by  fpeedy  wear. 

Laftly,  it  feems  to  be  a  queftion  or  doubt,  which  well  deferves  to  be  refolved  by  further 
experiment,  whether,  in  any  cafe  of  reiterated  or  long  continued  a£tion,  the  fofter  metals' 
can  be  made  to  work  in  contaft  with  each  other,  in  the  way  of  clofc  fitting,  with  as  little 
tefiftance  and  wear  as  when  an  organifed  fubftance  containing  oil  or  fat  is  interpofed. 

When  one  individual  fpeaks  to  the  world  concerning  the  works  of  another,  the  tranf- 
aftion  is  naturally  accompanied  with  a  fenfe  of  perfonality.  As  this  fenfe  ought  not  to 
kad  men  into  unworthy  a<£tions,  fo,  on  the  other  hand,  it  ought  not  to  prevent  their  ful- 
filling any  duty  which  may  call  upon  them.  Convinced  that  no  vindication  or  apology  is, 
neceflary  in  defence  of  a  fcientific  examination  of  every  objedl  which  is  offered  to  the- 
public  acceptance,  I  have  fpoken  freely  of  a  conftru£lion  which,  from  its  ingenuity,  might; 
be  thought  of  greater  value  than  it  really  is  ;  but  which,  when  carefully  examined,  appears, 
to  be  Inferior  to  the  methods  already  in  ufe. 


xir  //;- 


Ti 


Nitv  Jmmal  Acid,  er  the  Zoonlc  Acid.  367 

XII. 

Jtiformatlon  refpeBhi^  the  Zoonic  Acid,  difcovered  by  BeRTHOLLET, 


H  E  fluid  *  obtained  by  diftillation  from  animal  fubftances  has  been  hitherto  thought 
to  contain  no  other  principle  than  carbonate  of  ammoniac  and  an  oil.  Berthollet  has  af- 
certained  that  it  contains  an  acid,  to  which  he  has  given  the  name  of  zoonic  acid.  He 
has  afcertained  its  prefence  in  the  fluid  obtained  from  the  gluten  of  wheat,  the  yeaft  of 
beer,  bones,  and  woollen  rags,  diftilled  for  the  preparation  of  the  muriate  of  ammoniac} 
and  be  thinks  himfelf  authorized  to  confider  it  as  the  product  of  diftillation  of  all  animal 
fubftances. 

In  order  to  feparate  this  acid,  he  mixes  lime  with  the  fluid  afforded  by  this  deflru£llvc 
difiillation,  after  having  feparated  the  oil.  The  mixture  is  then  boiled  or  diftilled,  to 
feparate  the  carbonate- of  ammoniac.  When  the  odour  ceafes  to  be  penetrating,  he  filters 
and  adds  a  fmall  quantity  of  lime  to  the  liquid,  which  he  again  boils  till  the  odour  of  am- 
hioniac  has  entirely  difappeared.  What  remains  is  the  zoonate  of  lime,  which  he  again 
filters.  To  this  he  then  adds  the  aqueous  folution  of  carbonic  acid,  or  otherwife  he  blows 
through  a  tube  into  the  liquor,  in  order  to  precipitate  any  lime  which  might  exift  in 
the  uncombined  ftate.  The  zoonate  of  lime  may  then  be  ufed  to  produce  other  com- 
pounds by  double  afHnity  ;  or  the  pure  zoonic  acid  may  be  had  by  the  following  procefs  : 
The  well  concentrated  aqueous  folution  of  zoonate  of  lime  is  to  be  mixed  with  phof- 
phoric  acid,  in  a  tubulated  retort,  and  expofed  to  diftillation.  The  zoonic  acid  is  not 
very  volatile,  but  requires  a  degree  of  heat  nearly  equal  to  that  of  boiling  water  to  raife 
•it.  The  fluid  muft  therefore  be  boiled ;  and  if  two  fucceffive  receivers  be  at  the  fame 
tirrie  adapted,  it  will  not  be  driven  into  the  fecond.  Part  of  the  acid  feems  to  be  deftroyed 
by  the  a£l:ion  of  the  heat ;  for  the  liquor  becomes  brown  by  the  ebullition,  and  towards 
the  end  of  the  procefs  black  :  whence  it  may  be  concluded  that  this  acid  contains  carbone, 
Berthollet  did  not  examine  the  other  principles  which  are  difengaged  during  the  decom- 
pofition. 

The  zoonic  acid  has  a  fmell  refembling  meat  which  has  been  roafted ;  a  procefs  in  which 
it  is  indeed  formed.  Its  tafte  is  auftere,  and,  from  the  few  experiments  of  Berthollet,  no 
remarkable  properties  were  exhibited.  It  ftrongly  reddens  paper  tinged  with  turnfol,  and 
effervcfces  with  alkaline  carbonates.  It  did  not  appear  to  him  to  afford  cryftallizable  falts 
with  earths  or  alkaline  bafes.  It  afforded  a  white  precipitate  in  the  aqueous  folution  of^ 
acetite  of  mercury,  and  in  that  of  nitrate  of  lead  ;  fo  that  it  has  a  flronger  attradion  to 
the.oxydes  of  mercury  and  lead  refpeftively  than  the  acetous  and  nitric  acids.  It  docs 
not  a£t  on  the  nitrate  of  filverbut  by  double  affinity.  The  precipitate  which  then  falls 
down  becomes  brown  in  time,  and  therefore  contains  hydrogen.  The  zoonate  of  potafh 
calcined  did  not'  afford  prufllate  of  iron  with  a  folution  of  that  metal.  A  liquid,  pof- 
fefllng  all  the  characters  of  acidity,  was  feparated  from  flefli,  which  Berthollet  had  kept  a 
long  time  in  a  ftate  of  putrefaftion  ;  but  it  was  an  ammoniacal  fait  with  excefs  of  acid. 
This  acid,  combined  with  lime,  appeared  to  him  to  refemble  the  zoonate  of  lime ; 
but  the  quantity  he  had  was  too  fmall  to  admit  of  its  identity  with  the  zoonic  acid  being 
accurately  determined. 

•  Nearly  in  the  words  of  Berthollet,  in  the  Annales  de  Chimie,  xwi.  86. 

3  B  2  XIII,  HiHi- 


368  Cittcernlfig  the  Prlorti^  tf  var'mn  Difcoveritt. 

xai. 

■HiJIoncal  Notes  concern'wg  the  Invention  of  the  Jlr  Pump  with  Metallic  Valves ;  the  Necejfitf 
of  jilioli  to  produce  the  cryfallized  Salt  called  Alum  ;  and  the  ekBrkal  Injlrument  tno-wn  by 
the  name  of  the  Revolving  Dottbler.  (W.  N.) 

C>iITlZEN  ADET,  in  vol.  xxv,  of  the  Annales  dc  Chimle,  p.  165,  claims  the  invention' 
of  an  air-pump  for  Cit.  Ami  Argand,  at  Paris,  in  the  year  1776,  of  which  that  of  Cuth- 
bertfon  is  faid  to  be  an  imitation.  Reference  is  made  to  the  notes  on  the  third  volume  of 
the  Lepns  Eiementaires  de  Fh^ique,  de  Sigaud  de  la  Fond,  for  a  defcription. 

I  am  happy  in  this  opportunity  of  doing  honour  to  a  philofopher  and  mechanic,  with 
whofe  ability  I  am  well  acquainted.  That  tenacity  with  regard  to  the  credit  arifing  fromlirft 
thoughts  or  inventions,  and  the  partiality  which  leads  men  to  exult  in  the  nationality  of  dif- 
covery,  are  eftimable  qualities  on  the  whole,  becaufe  they  tend  to  the  promotion  of  fciencej 
but  they  fometimes  lead  to  infinuations  oi  mala  fide;  in  cafes  where  the  coincidences  of  rea- 
foning  have  alone  produced  fimilar  refults.  On  this  occafion  it  feems  proper  to  remark,  that 
Mr.  Cuthbertfon  has  candidly  difplayed  the  fource  from  which  he  derived  his  information, 
and  that,  upon  the  whole,  it  appears  highly  probable,  as  well  from  the  refpe£lable  charac- 
ters  of  the  individuals,  as  from  the  general  circumftances  of  the  cafe,  that  this  artift,  as 
%vcll  as  Pacts  van  Trooftwyk,  Dr.  Rutherford,  and  Sir  George  Mackenzie,  would  have  done 
Juftice  to  the  invention  of  Mr.  Argand,  if  they  had  been  acquainted  with  it  *. 


In  the  fame  Annales,  xxiii.  ^2^,  there  is  a  claim  on  the  part  of  the  celebrated  Chaptai 
refpeftlng  the  difcovery  of  the  nature  and  triple  compofition  of  alum,  communicated  to 
the  Inftitute  by  Vauquelin'f.  To  which  this  laft  chemift  has  anfwered,  in  vol.  xxv.  p.  107, 
that  he  was  unacquainted  with  the  labours  of  Chaptai  in  that  refpedt,  and  had  communi* 
cated  his  own  memoir  to  the  Inftitute  a  fortnight  before  Cit.  Chaptal's  memoir  arrived  ; 
and,  laftly,  that  the  priority  and  merit  of  the  difcovery  belong  to  Cit.  Pefcroifilles,  whofe. 
Tcfearchcs  concerning  the  nature  of  alum  were  publilhed  by  Berthollct,  in  his  Art  of  Dyeing, 
long  before  that  time. 


Another  inftance  in  which  I  am  in  fome  degree  concerned,  affords  a  curious  example 
of  the  flownefs  with  which  the  Improvements  of  philofophical  apparatus  are  in  fome  cafes 
communicated.  In  the  22d  number  of  the  Bibliotheque  Brlttannique,  there  is  an  account 
of  the  doubler  of  eledrlcity  of  John  Read.  The  procefs  of  accumulating  eleftricity ;{:  by 
doubling,  was  invented  by  Lichtenberg  and  Klincock,  and  greatly  improved  by  Bennett, 
who  applied  it  to  Volta's  condenfer.  In  1787,  Dr.  Darwin  conftru6led  a  machine  for 
performing  the  procefs  in  part  mechanically,  and  in  1788,  I  made  and  communicated  to 
the  Royal  Society  the  Revolving  Doubler  by  which  the  whole  aft  is  reduced  to  the 
fimple  turning  of  a  winch.  Five  years  afterwards,  namely  in  1793,  ^'^-  John  Read  pub- 
lifted  his  "  Summary  View  of  Spontaneous  £le£tricity,  &c."  in  the  4th  chapter  of  which  he 

*  On  this  fubjeft,  fee  our  Journal,  II.  2S.  f  Philof.  Journal,  I.  31  J, 

J  Plijlof.  Journal,  I.  396. 

gives 


Revolving  DoiilIei'.-—SJturation  ef  Alkali  luith  Carben'tc  Acid.  369 

gives  a  defcription  of  my  inftrument  in  my  own  words,  copied  without  acknowledgment 
from  the  Philofophlcal  Tranfadions  for  1788,  but  difguifed  in  a  fmall  degree  by  a  new  de- 
nomination in  the  title,  and  an  unneceflary  lengthening  of  the  infulating  parts,  which 
before  were  upwards  of  ten  times  the  length  of  the  interval  between  plate  and  plate.  It 
is  evident,  therefore,  that  of  all  the  individuals  who  have  written  on  this  inftrument,  the 
credit  of  the  invention  has,  in  t  798,  been  beftowed  on  the  perfon  who  has  the  leaft  claim 
to  philofophical  invention  or  candid  narrative. 


XIV. 

Defci  iption -of.  an  Apparatus  for  fatttrating  PoUaJb  and  Soda  with  Carbonic  Acid, 

By  Citizen  WeltheR*,- 

T     .     .        >  . 

X  H  E  intention  of  this  apparatus  is,  to  afford  an  uninterrupted  contaft  between  the 
alkali  and  the  carbonic  acid  gas,, and  to  proportion  the  difengagement  of  the  gas  to  its 
fixation. 

Fig.  I.  platt  XVI.  reprefents  the  complete  apparatus.  It  is  compofed  of  four  diftinift 
parts,  A,  B,  C,  D.  The  firft.  A,  ferves  for  the  difengagement  or  production  of  the  car- 
bonic acid  gas,  whence  it  is  diilributed  into  the  apparatus.  The  fecond,  B,  conne£ts  all- 
the  feveral  parts  of  the  apparatus  together.  The  third,  C,  is  the  refervoir  for  carbonic  acid- 
gas.  1  he  principal  funflion  of  this  part  is  to  fupply  gas  to  the  alkali  in  proportion  as  the 
abforption  takes  place.  And  the  fourth,  D,  contains  the  alkali  which  is  to  be  faturated,  ilk' 
cx)nta£t  with  the  carbonic  acid.' 

Each  of  thefe  parts  requires  a  particular  defcription. 

The  part  A,  confifts  of  a  bottle  with  two  necks  a,  by  (the  third,  c,  is  not  heceflary).     This- 
bottle  contains  fulphuric  acid  diluted  with  four  parts  of  water,  to  the  height  d. — Tihe  neck  a,  • 
receivesatubeif'^'^,  of  which  the  upper  part /<•',  diverges  Hke  the  bafe  of  a  funnel,  and  the 
lower  part  f,  which  paffes  through  the  cork  and  enters  the  bottle,  is  drawn  out  by  the  lamp, , 
in  fuch  a  manner,  that  the  portion  of  tube  which  is  in  the  ftopper  has  the  fame  internal  dia- 
meter as  the  extremity  1:  of  the  ftem/,  reprefentedj*^.  2,  A;  and  that  the  orifice  r  within' 
the  bottle,  is  only  two  millimetres  in  diameter  (^y  of  an  inch)  |.     Into  the  tube^V* 
enters  the  ftem  or  ftick  of  glafs  fy  reprefented  fg.  2, ,  A,  the  lower  extremity  of  which  is  ■ 
bound  with  flax,  fo  that  it  ferves  as  a  ilopper  in  the.contradted  part  of  the  tube,  and  does 
not  permit  its  contents  to  flow  into  the  bottle  a,  unlefs  that  ftopper  be  raifed. — The  neck  b' 
contains  a  tubei/.i/j  bended  into  two  angles,  and  forming  a  communication  between  A'- 
andB. 

The  part  B,  confifts. of  a  bottle  with  five  necks  a  bfi  h,  of  which  the  plan  is  reprefented  ' 
jig.  3, 3.     This  bottle  contains  water  as  high  as  /. — ^The  neck  h  receives  the  tube  h  h  h^. 

•  This  apparatus  was  conftrufted  in  die  firft  month  of  the  third  republican  year.' .  The  defcription  i>  tranflatej  : 
from  the  Annalcs  de  Chimie,  xxv:i.  53. 

f.  The  tube  e"  c'  e  may  be  made  out  of  a  fmall  matrafs  with  a  long,neck.  The  bottom  may  be  taken  away,  . 
leaving  about  half  the  lioiiy,  wh'.ch  will  form  the  pan  c'  e'  of  the  tube  ;  the  neck  will  afford  the  partaa,  and  the  . 
extnemity  of  the  neck  foftentd  and  drawn  out  by  the  lamp  to  the  above  dimenfioas,  will  afford  the  extremity  e,  W.  ■ 

proceeding ; 


^0  Saturation  o/Alhali  with  Ccirhtnic  Acid. 

proceeding  from  tlie  bottle  A. — The  neck  b  contains  a  ftrait  tube  g g\  wbofe  extremity  g' 
is  plunged  in  the  water  to  the  depth  of  one  or  two  centimetres  (about  \  of  an  inch.)  It 
ferves  to  (hew  the  comprcflion  to  which  the  carbonic  acid  gas  is  fubjefted  in  the  apparatus. 
— The  neck  a  contains  a  ftiait  tube  a'  a,  which  allows  a  communication  to  be  formed  at 
■plcafure  from  the  interior  part  of  the  bottle  B,  with  the  atmofpliere,  by  means  of  an  appara- 
tus of  tubes  fhewn  in^^  4,  B.  The  tube  a'  a  has  two  ftoppers  at  m  and  n  :  the  flopper  m 
enters  the  tube  w  w,  enclofing  the  tube  a'  a  ;  in  tlic  interval  between  thefe  two  tubes  upon 
tlicftcpper  m,  mercury  ij  poured  to  the  height  r  of  twelve  or  fifteen  millimetres  (about  |- 
ah  inch) :  the  tube  a' a  is  then  covered  by  a  third  tube  Jclofed  above,  which  being  in>mer- 
fed  Tit  pm  into  the  mercury,  interrupts  the  communication  of  the  atmofphere  with  the 
orifice  a'  of  the  tube  a'  n,  and  confequently  clofes  the  bottle  B,  when  the  ftopper  /;  is  placed 
in  the  neck  a. — The  neck  /  contains  a  tube  / ;,  compofed  like  the  former  a'  a  ;  but  of  which 
the  intermediate  tube  000  twice  recurved,  eftabliibes  a  cominunication  between  the  bottle 
B  and  the  rei'ervoir  C. — The  lafl  neck  y  contains  a  tubey//',  twice  recurved,  which  elta- 
blifhes  a  communication  between  the  bottles  B  and  D. 

The  partC  is  compofed  of  a  tub  /,  in  the  fide  of  which  there  is  a  hole  at  a  fmall  diftance 
above  the  bottom  a  a. — In  this  lateral  hole  is  inferted  a  perforated  ftopper,  the  interior  ori- 
fice of  which  receives  a  tube  bl'b"b,  bended  into  a  right  angle,  of  which  the  portion  b'  mud 
be  bended  in  fuch  a  manner,  that  the  angular  part  h"  may  touch  the  bottom  a  a  oi  the  tub, 
which  renders  it  more  firm  in  its  pofition.  In  the  external  orifice  of  this  cork,  or  ftopper, 
there  is  fcrewed  a  brafs  cock  r,  of  which  the  part  c  receives  a  tube  c  c'  c"  c,  bended  at  <•, 
to  rife  vcrtlcailly,  and  from  c'toc"t.o  bind  againft  the  frame  del.  This  tube,  at  the  height^, 
is  compofed  like  that  of  a' a,  defcribed7%.  4,  B.  It  there  receives  the  tube  000,  which  affords 
a  communication  with  B. — The  pieces  which  are  applied  to  the  hole  b  of  the  tub,  are  luted ; 
the  inner  with  graver's  wax,  and  the  outer  with  fat  lute. — In  the  tub  /,  containing  water 
to  the  height  e  ee,  there  enters  an  inverted  jar  C,  provided  with  a  copper  cock  at  /  and  m. 
This  jar  is  fufpended  at  g  by  a  ftring,  which  paffes  over  the  pulleys  h  h,  and  fupports  at  /,  a 
weight  K,  fomewhat  lefs  heavy  than  the  jar  itfelf,  when  entirely  plunged  in  the  water  con- 
tained in  the  tub. — When  the  jar  C  is  totally  immerfed  in  the  tub,  it  will  reft  on  two  pieces 
of  wood  about  two  or  three  centimetres  thick,  which  are  fixed  at ///near  the  inner  circum- 
ference of  the  bottom  a  a  oi  the  tub  (feefg.  5,  C,  which  reprefents  the  plan  of  the  tub  j 
and  Jig.  6,  which  reprefents  the  vertical  fcdion  as  far  as  A  B),  fo  that  the  bafe  /'  /'/'  of  the 
jar  cannot  touch  the  tube  b. 

The  p:.rt  D  confifts  of  a  bottle  with  three  necks,  a,  b,  c.  The  neck  a  receives  a  tube 
oa'  a,  proceeding  to  a  fmall  bottle  d,  containing  water  as  high  as  e. — The  neck  b  receives 
the  tube  ///'  proceeding  from  the  bottle  B  -,  this  tube  ought  to  poflefs  a  diameter  of  about 
two  centimetres  (|  of  an  inch)  at  its  orifice/'. — The  neck  r  contains  a  fyphon  gg',  commu- 
nicating with  the  bottle  /,  of  which  the  branch  g '  ought  to  be  longer  than  g. — The  bottle  / 
has  three  necks,  h,  i,  i. — It  receives  in  its  neck  i,  the  fyphon  gg';  in  the  neck  i,  a  tube  b  by 
■with  one  fingle  bend  ;  and  the  neck  «  remains  free.     It  is  to  be  corked. 

After  the  formation  of  the  apparatus  by  uniting  the  four  parts  here  defcribed,  each  of 
*hem  demands  a  particular  preparation  before  the  operation  can  be  proceeded  upon. 

The  tube  /  e^  e  oi  the  part  A  is  to  be  filled  with  carbonate  of  lime  mixed  with  water.— 
Through  the  neck/?i  of  the  bottle  /,  in  the  part  D,  that  bottle  is  to  be  filled  with  alkali.  The 

neck 


Saturaiteti  e/ Alkali  ivlth  Carhonic  AclJ.  37 1 

nrck  h  is  then  to  be  ftopped  with  its  cork,  and  by  blowing  through  the  tube  K  the  alkali  is- 
to  be  forced  through  the  fyphon  g'  g  into  the  bottle  D.  The  air  contained  in  this  laft  bottle 
efcapcs  through  the  tube  a  a'  a,  and  pafles  through  the  water  of  the  fmall  bottle  d.  The 
fluid  becomes  nearly  on  a  level  in  the  bottles  D  and  /,  and  the  extremity  of  the  tuhefffy. 
which  conne£ts  the  bottles  B  and  D,  is  plunged  in  the  alkali. — Proceeding  then  to  the  part 
c,  the  cock  m  of  the  inverted  veflel  is  to  be  opened,  while  that  of  the  tub  r  is  kept  {hut.  By  the 
^xcefs  of  weight  of  the  jar  beyond  that  of  K  it  finks  in  the  tub,  and  becomes  filled  with  water^ 
while  the  common  air  it  contained  efcapes  at  g. — As  foon  as  the  inverted  veflel,  being  to- 
tally immcifed  in  the  tub,  repofes  on  the  circular  fegments  ///,  the  orifice  of  the  upper 
tube  of  the  tube  b  is  found  in  the  brafs  receptacle  /.  It  is  neceflary,  that  the  level  of  the- 
water,  which  by  the  immerfibn  of  the  inverted  veflel  may  have  rifen  from  e  to  e',  fhould 
have  the  elevation  ^^'of  the  tube  b  equal  at  lead  to  two  centimetres  higher,in  order  that  this- 
tube  may  not  be  clofed  by  the  water,  which  would  prevent  the  gas  from  entering  into  the 
veflel  C. — When  this  laft  veflTel  is  full  of  water,  its  cock  /  muft  be  fliut,  and  the  cock  r  of  the 
caflc  muft  be  opened- 

In  this  difpofition  of  the  apparatus,  the  glafs  ftem/"of  the  part  A  is  to  be  raifed,  and 
carbonate  of  lime  gradually  introduced,  which  falling  upon  the  fulphuric   acid  becomes 
decompofed,  and  lofesits  carbonic  acid.     Thislafl:  poflefling  the  elaftic  ftate,  pafl"es  through' 
the  tube  h  h  h  into  the  bottle  B.     The  tube  d  is  then  to  be  raifed,  in  order  that  the  atmo- 
fpheric  air  contained  in  the  bottles  A  and  B  may  flow  out ;  after  which,  the  neck  a  of  the 
bottle  B  is  to  be  clofed,  by  replacing  tube  d.     In  this  fituation  the  carbonic  acid  gas,  which; 
enters  B,  (meeting  lefs  refiftance  in  its  paflage  to  the  inverted  veflel  through  the  tubes  f  r 
and  000,  than  to  pafs  into  the  part  D  by  the  tube  fff,  which  is  plunged  in  the  alkali)  raifcs- 
and  fills  the  vefl"el  c. — As  foon  as  this  event  has  happened,  no  more  carbonate  of  lime  is  to- 
be  introduced  into  the  bottle  A,  and  the  bottle  D  is  filled  with  alkali  by  blowing  through 
tlie  tube  K  of  the  bottle  /.    The  levels  of  the  alkaline  fluid  are  at  the  height  n  in  the  bottle- 
D,  and  m   <  «  in  the  bottle  / ;  and  the  fluid  tending  to  its  level,  by  means  of  the  fyphoni 
gg',  the  furface  «  falls,  and  produces  a  vacuum  in  the  bottle  D. — ^The  carbonic  acid  gas  is^ 
then  drawn  into  the  bottle  D  by  the  tube///';  at  the  fame  time  that  the  water  of  the  fmalli 
bottle  d  (part  D)  rifes in  the  tube  a  a'  a;  but  the  height  of  this  tube  is  fuch,  that  the  car- 
bonic acid  gas  can  enter  the  bottle  D  before  the  water  rifes  to  a'  in  the  tube  a  a'  a., — The- 
two  furfaces  «  and  m  acquire  an  equilibrium  in  the  bottles  D  and  /,  and  the  carbonic  acid 
gas,  which  occupies  the  upper  part  of  the  bottle  D,  combining  with  the  pot-afh,  a  vacuum 
is  formed,  which  is  continually  fupplied  with  new  gas. — When  the  veflel  C  is  nearly  cx« 
haufted  of  its  gas,  it  muft  be  filled  by  a  new  difcngagement. 

N.  B.  As  the  carbonic  acid  gas  is  mixed  with  a  fmall  portion  of  atmofphericair,  this  air^, 
which  is  not  abforbed  by  the  pot-afli,  accumulates  in  the  bottle  D,  and  may  flop  the  ope- 
ration. It  muft  be  driven  out  by  blowing  into  the  tube  3  of  the  bottle/,  and  filling  the- 
bottlcL  D- with  alkali. 


XV.  JhflraSff 


^7-*  On  the  fifw  Mtlal,  TeUurttim, 

XV.    ■ 

jlhJiraB  of  a  Memoir  of  KlaPROTH,  on  a  new  Aletal  cJet:om!iiatcd  Tellurium.       Rend  at 
tl>e  Public  Sejfion  of  the  Academy  of  Sciences  at  Berlin,    January  the  2^th,   1798*. 


K, 


.LAPROTH,  the  chemift;  of  Berlin,  in  the  chemical  analyfis  of  the  auriferous  ore, 
known  by  the  name  of  the  white  ore  of  gold  (weifs  goklerz),  aurum  psradoxum,  metalluni 
vel  aurum  problematicum  f,  has  difcovered  in  that  mineral,  a  metal  abfolutely  diflerent 
from  all  thofe  which  have  hitherto  been  known,  to  whicii  he  has  given  the  n^ime  of  Tel- 
lurium, forming  a  kind  of  feries.or  arrangement  with  the  new  metals  difcovered  by  him 
■fome  time  ago,  and  denominated  Uranium  and  Titanium.  Mr.  Muller  of  Reichenftein, 
in  the  year  1782,  had  fufpedled  the  exiftence  of  a  peculiar  metallic  fubflance  in  this  mine- 
•ral.  Bergman,  to  whom  he  had  forwarded  a  fpecimen  of  the  ore,  confirmed  his  fufpicion  ; 
,but  on  account  ofthe  fmall  quantity  upon  which  he  operated,  he  did  not  think  fit  to  decide, 
■whether  this  fofiil  did  aiftually  contain  a  new  metal,  or  whether  it  might  not  be  antimony 
^vhich  he  had  miftaken  for  a  new  prot!u£i.  The  numerous  and  ingenious  experiments  to 
which  Klaproth  has  fubjefted  a  more  confiderable  quantity  of  this  ore,  which  was  fent  to 
iiim  by  Mr.  Muller  J,  perfectly  confirm  the  fufpicions  of  that  chemift,  and  of  Bergman. 

The  Procefs  for  obtaining  this  Aletal  from  its  Ore, 

1.  A  portion  of  the  ore  is  gently  heated,  with  fix  parts  of  muriatic  acid  ;  three  parts  of 
nitric  acid  are  then  to  be  added,  and  the  mixture  fubjedled  to  ebullition.  A  very  confider- 
able effervefcence  takes  place,  and  the  folution  becomes  complete- 

2.  The  .filtered  folution  is  to  be  diluted  with  as  much  water  as  it  can  bear  without  becom- 
ing turbid,  which  quantity  is  very  little.  A  folution  of  cauftic  pot-afh  is  then  to  be  added, 
until  the  white  precipitate,  which  is  at  firft  formed,  (ball  difappear,  and  nothing  but  a  brown 
depofition  in  flocks  fhall  remain. 

3.  Thislaft  precipitate  is  a  mixture  ofthe  oxides  of  gold  and  of  iron,  which  maybe  fepa- 
rated  by  the  ufual  methods. 

'  4.  To  the  alkaline  folution  (2),  muriatic  acid  muft  be  added,  fufficient  for  the  perfe£t 
faturation  of  the  alkali ;  but  not  in  excefs.  A  white  and  very  abundant  precipitate  it 
afforded,  which,  on  the  application  of  heat,  falls  to  the  bottom  of  the  vefFel  in  the  form 
of  a  heavy  powder.  After  wafliing  and  drying  this  precipitate,  it  is  to  be  formed  into  a 
kind  of  pafte,  with  a  fufficient  quantity  of  any  fat  oil  ;  and  this  mafs  is  introduced  into  a 
fmall  glafs  retort,  to  which  a  receiver  is  loofely  to  be  applied.     In  this  difpofition  of  the 

•  This  abftraft  was  communicated  on  the  part  of  the  author,  by  M.  Rofe,  i  chemift  of  Berlin,  and  was  tranf- 
jated  and  forwarded  to  the  Phylomatic  Society  at  Paris,  by  L.  Hecht  the  younger.  The  French  tranflation, 
which  of  courfe  I  muft  follow  (a?  the  original  is  unpubliflied),  is  inferted  in  the  xxvth  vol.  of  the  Annales  de 
Chimie,  p.  t73» 

.f.  This  mineral  is  found  in  the  mine  called  Afar/nA/T^,  in  the  Fatzbay  maviMzxn^  nesx  Zaletbna  in  Iraiifilvania. 
Sec  Emmerling's  Elements  of  Mineralogy,  II.  124.  et  feq.  (orKirwan,  II.  324.    N.) 

+  In  the  origiBal  the  words  are  "  M.  de  Reichenftein,"  which  I  fuppofe  to  be  an  overfight,  and  that  I  ara 
♦orreft  in  tranflating  the  words  M.  Muller  de  Reichenftein  which  occur  a  few  lines  before,  on  the  fuppofuion  that 
'%/l,  Muller  aitually  r«fides  at  Reichenftein,  without  deriving  any  titular  name  from  that  town.    N. 

apparatus. 


Onihe  new  Meia!,TelMriumi'^  373 

ipparatus,  heat  is  gradually  to  be  applied  to  ignition.  I ii  proportion  is  "the  oil  becomes 
decompofed,  brilliant  metallic  drops  are  obfcrved,  fimilar  to  thofe  in  thi  diftillation  6f 
mercury,  which  line  the  upper  part  of  the  retort^  and  run  down  at  intervals  to  the  bottom 
^f  the  vcflel,  immediately  after  which'  they  are  replaced  !)y  others.  After  the  cooling, 
thefe  metallic  drops  arc  found  congealed,  and  adhering  to  the  fides  of  the  retort  and  the 
bottom  of  the  veflel ;  and  the  reft  of  the  metal,  reduced  in  thfe  form  of  a  button  with  ii 
brilliant  furface,  moft  com^monly  prefenting  a  cryftallized  face. 

The  ejjential  Characters  cf  this  luiv  Mital. 

1.  Its  colour  is  white  like  tin,  but  inclining  to  a  leaden  grey^  Its  metallic  fplcndor  is 
confiderable  ;  its  frafture  lamellated  (gerade  blattrig)^.  It  is  very  brittle  and 'friable,  anA 
by  flo A' cooling  it  readily  acquires  a  cryilallized  furface.  i-:     •    '   k- 

2.  Its  fpecific  gravity  is  6,115. 

3.  It  belongs  to  the  clafs  of  the  mod  fufible  metals. 

4.  Heated  with  the  blow-pipe  upon  charcoal  it  burns  with  a  flame  confiderably  brilliant, 
of  a.  blue  colour,  butgreenifli  at  the  edges  -,  it  rifes  totally  in  a  grey  whitifli  fume,  and 
emits  a  difagreeable  fmell,  which  approaches  that  of  radifhes.  If  the  flame  be  with- 
drawn before  the  fmall  portion  fubje£led  to  the  heat  is  entirely  volatilized, 'the  remaining 
button  prefervcs  its  fluid  ftate  for  a  long  time,  and,  during  the  refrigeration,  becomes 
covered  with  a  radiated  vegetation. 

5.  This  metal  amalgamates  eafily  with  mercury. 

'■  '6.  With  fulphur  it  forms  a  fiilphuret  of  a  leadeh-grey  colour,  and  radiated  ftru(n.ure. 
•  "'7-  Its  folution  in  the  nitric  acid  is  clear  and  colourlefs  i  when  concentrated,  it  fpontai 
rieoufly,  in  the  courfe  of  time,  afl!brds''fman  white  anU\light  cryftals  in  the  form  of 
needles,  which  pofl"ers  the  dendritic  aggregation.  '  ^-"  •• 

8.  The  new  metal  is  likewife  foluble  in  the  nrtro-muriatifc"'9'cid  :  when  a  large  quantity 
of  water  is  added  to  a  folution  of  this  nature,  the  metal  falls  tlown  in  the  ftate  of  oxide, 
in  the  forte  of  a  white  powdei*,lvbich  in  this  ftate  is  foluble  in  the  murlajtlc  acid. 

g.  When  a  fmall  quantity  of  this  metal  is  mixed  in  the  cold,  with  one  hundred  times 
Its  weight  of  concentra'ted  f.jlphuric  acid,  in  a  clofed  veflel,  the  fltiid  gradually  dflumes 
a  beautiful  crlmfon  red  colour.  By  the  addition  of  a  fmall  quantity  of  water,  added  drop 
by  drop,  the  colour  difappears,  and  the  minute  portion  of  metal  which  was  diflblved 
falls  down  in  the  form  of  black  flocks.  Mere  heat  alfo  deftroys  this  folution ;  it  caufes  the 
red  colour  to  dlfappear,  and  difpofes  the  metal  to  feparate  In  the  ftate  of  a  white  oxide. 

10.  When,  on  the  contrary,  the  concentrated  fulphuric  acid  is  diluted  with  two  or 
three  parts  of  water,  and  a  fmall  quantity  of  nitric  acid  is  added,  this  mixture  difl'olves  a. 
confiderable  portion  of  the  metal,  The  folution  Is  clear  and  colourlefs,  and  Is  not  decom- 
pofed  by  the  mixture  of  a. greater  quantity  of  water, 

11.  All  the  pure  alkalis  precipitate  from  the  add  folutlons  of  this  metal  a  white  oxide, 
foluHc  in  all  the  acids.  The  precipitate  is  entirely  foluble  by  excefs  of  alkali.  If  a  car- 
bonate be  ufed  inftead  of  a  pure  alkali,  the  fame  phenomenon'takes  place  5  with  this  dif- 
ference, however,  that  by  an  excefs  of  the  carbonate  the  precipitate  which  is  formed  is 
rcdiflblved  In  part  only. 

yot.il— Nov.  1798.  3C  12.  A 


374  CharaBers  tf  the  nno  Meta!,  Telliiriunt' 

12.  A  very  pure  prufliate  of  potafh  occafions  no  precipitate  in  the  folutions  of  this 
metal.  This  is  a  remarkable  exception  to  the  general  rule  of  metallic  precipitations  j 
which,  however,  it  partakes  with  gold,  platina,  and  antimony. 

13.  The  alkaline  fulphurcts,  mixed  with  the  acid  folution,  occafion  a  brown  orblackiflx 
precipitafe,  accordingly  as  the  metal  is  combined  with  more  or  lefs  of  oxygen.  It  fome- 
timcs  happens  that  the  colour  of  the  precipitate  perfeQly  refembles  kerraes  mineral,  or 
the  red  fulphurated  oxide  of  antimony.  When  the  fulphuret  of  tellurium  is  expofed  on 
an  ignited  coal,  the  metal  burns  with  a  blue  colour,  together  with  the  fulphur. 

14.  The  infufion  of  the  nut-gall,  combined  with  the  fame  folutions,  affords  a  precipi- 
tate in  flocks  of  an  Ifabella  colour. 

15.  Iron  and  zinc  precipitate  tellurium  from  its  acid  folutions  in  the  metallic  ftate, 
under  the,  form  of  fmall  black, flocks,  which  refume  the  metallic  brilliancy  when* rubbed, 
and  are  fufcd  into  4  metallic  button  upon  an  ignited  coal. 

16.  Tin  and  antimony  occafion  the  fame  phenomenon  with  the  acid  folutions -of  the 
new  metal.  The  -precipitate  formed  by  antimony  proves,  in  the  moft  ftriking  manner, 
that  tellurium  is  not  antimony  difguifed,  as  had  been  fuppofed.  The  folution  of  tin  in 
the  muriatic  acid,  mixed  with  a  folution  of  tellurium  in  the  fame  acid,  likewife  produces 
a  black  metallic  precipitate. 

17.  The  oxides  of  tellurium,  obtained  frOm  the  acid  folutions  by  alkalis,  or  from  al- 
kaline folutions  by  acids,  are  in  either  cafe  reduced  with  a  degree  of  rapidity  approaching 
to  detonation,  by  expofure  to  heat  upon  charcoal.  It  burns,  and  is  volatilized,  as  has^ 
already  been  mentioned. 

18.  By  the  application  of  heat,  for  a  certain  time,  In  a  retort,  this  oxide  of  telluriura 
becomes  fufed,  and,  when  cold,  appears  of  a  flraw  colour,  with  a  kind  of  radiated  texture. 

ig.  With  the  addition  of  any  fat  fubftance,  the  oxide  of  tellurium  is  pcrfeftly  reduci* 
ble  by  the  method  before  defcribed. 

The  white  ore  of  gold  from  Fatzhay,  aurum  vel  metallum  problematicum,  contains,  i» 
loco  parts,  tellurium  in  the  metallic  ftate,  925,5;  iron,  72,0;  gold,  2,5. 

The  graphic  gold  of  OfFenbanya  contains,  in  100  parts,  tellurium  in  the.  metallic- 
ftate,  ^Oj  gold,  30 ;  filver,  10. 

:    The  mineral  known  by  the  name  of  the  yellow  ore  of  Nagyag  contains.    In  100  parts,' 
metallic  tellurium,  45,0',  gold,  27,0;  lead,  19,5  ;  filver,  8,5;  andof  fulphur  a  minute  portioni. 

The  mineral  known  by  the  name  of  the  grey  foliated  ore  of  gold  from  Nagyag  con* 
tains,  in  100  parts,  lead,  50;  metaUic  tellurium,  33  ;  gold,  8,5;  fulphur,  7,5  }-Ji1yet 
and  copper,  i. 


After  the  above  was  printed  In  the  Annales  de  Chimie,  the  editors  of  that  excellent 
work  received  a  tranflation  of  a  manufcript  addrefl'ed  by  M.  Klaproth  to  CIt.  Van  Mons,. 
on  their  behalf.  From  this  they  extradled  the  following  mineraloglcal  and  chemical  details  *  n 

The  colour  of  the  metallum  paradoxum,  of  the  mine  of  Fatzbay,  is  between  the  white  of 
tin  and  the  grey  of  lead  ;  it  has  much  metallic  brilliancy.  It  Is  fometimes  In  lumps,  and 
then  forms  an  aggregate  of  cryftalline  grains.    Its  texture  is  ufually  fine  or  fmalj  grained,. 

*  Atm.ales  de  Chimie,  xxv.  Ji?... 

Itfr 


Atcotfiit  of,  the  Ores  of  Tellurium,  J^jy 

Its  matrix  is  compofed  of  quartz  and  marl.     The  fubjecl'of  the  firft  analyfis  was  taken, 
from  a  piece  of  the  compadt  variety  detached  in  1780. 

The  graphic  gold  of  the  mine  Francifcus  at  OfFeubanya,  forming  the  fecond  variety,  is 
of  the  white  colour  of  tin,  partly  inclining  to  the  yellow  of  brafs :  it  is  very  brilliant, 
compofed  of  prifmatic  crydals,  flat  and  comprefled,  of  which  the  mutual  pofition  affedts 
the  form  of  the  characters  of  Turkilh  writing,  which  has  given  rife  to  its  empyrical  name. 
It  is  ufually  found  between  the  greyifh  blue  argillaceous  porphyry,  bedded  in  grey 
quartz.  The  proportion  of  the  conftituent  parts  of  tliis  ore  vary  much  :  the  middle  term 
lias  been  taken. 

The  third  variety,  called  the  yellow  ore  of  gold,  is  of  a  white  filver  colour  Inclining 
to  the  yellow  of  brafs,  compaft,  and  interfperfed  with  quartz  and  brown  fpar.  It  is 
cot  known  whether  that  fpecimen  which  prefents  radiations  of  confirierable  magnitude, 
and  exhibits  a  lamellated  texture  and  fra£lure,  is  of  the  fame  fpecies  :  it  is  fouiid  in  a 
mixture  of  quartz  cryftals,  and  brown  red  fpar,  and  fometimes  in  the  foliated  ore. 

The  foliated  ore,  or  grey  foliated  gold  ore  of  Nagyag,  differs,  in  its  chemical  and  mine- 
ralogical  charafters,  from  the  three  foregoing,  which  are  comprifed  under  the  name  of 
white  gold  ores ;  which  has  caufed  it  to  be  admitted,  in  the  new  fyflem  of  mineralogy, 
as  a  particular  fpecies  of  the  genus  Gold.  Its  colour  is  a  deep  leaden  grey,  inclining  to 
the  iron  black.  It  is  feldom  found  compadt,  but  mofl:  commonly  inferted  in  the  form  of 
fmall  united  leaves,  and  likewife  in  thin,  oblong,  hexahedral  tables,  partly  accumulated 
in  cavities.  Its  metallic  fplendor  is  but  moderate  :  its  fra£lare  moft  commonly  exhibits 
contorted  leaves ;  it  is  fpeckled,  and  in  fome  fpecimens  the  leaves  are  flightly  flexible.  Its 
matrix  is  compofed  of  quartz  mixed  with  reddifli  manganefe,  which  it  has  penetrated  in 
«vcry  dirc£lion. 

Scopoli,  Sage,  and  Ruprecht,  attempted  to  analyfe  this  ore  ;  but  the  difference  of  their 
tefults  rendered  their  experiments  very  uncertain.  They  had  clearly  afcertained  the  pre- 
fence  of  a  fubflance  volatile  by  heat ;  but  they  were  deceived  in  taking  it  fometimes  for 
trfenic,  and  in  other  inftances  for  antimony. 

It  is  to  M.  Von  Muller,  at  prefent  diredor  of  the  mines  at  Zalathna,  that  M.  Klap- 
roth  afcribes  the  honour  of  having  firfl  obferved  this  new  metal  (in  the  colledion  of  Me- 
moirs of  the  United  Friends  of  Vienna,  publiflied  by  Born).  He  cxprefles  his  acknow- 
ledgment for  the  fpecimens  he  fent  to  him,  which  enabled  him  to  prove  its  cxiftence.  He 
does  not  omit  the  obfervation,  that  Bergman,  though  he  durft  not  decide  concerning  the 
true  charadter  of  this  metallic  fubftance,  did  neverthelefs  declare  that  it  was  not  antimony. 

We  have  feen.  In  the  foregoing  abflrad,  (p.  372,  No.  3.)  that  the  precipitate' which  is 
not  re-difTolved  by  ammoniac  is  a  mixture  of  gold  and  iron.  There  are,  doubtlefs,  feveral 
methods  of  feparating  thefe  two  metals  \  but,  perhaps,  it  may  be  fatisfadlory  to  know  the 
method  which  was  ufed  by  M.  Klaproth.  He  re-diffolvcd  the  whole  in  the  nitro-muriatic 
acid,  and  precipitated  the  gold  by  a  folution  of  the  nitrate  of  mercury  made  without  heat, 
which  he  poured  gradually  into  the  former  folution,  till  the  precipitate  which  fell  down 
had  changed  Its  brown  colour  for  white.  The  precipitate,  being  carefully  colleifled,  was 
reduced  Into  pure  gold. 

"  I  {hall  give,"  fays  M.  Klaproth^  "  In  tlic  third  volume  of  m^  Beytraege,  &c.  the 

particulars  of  thcfc  analyfes  of  the  gold  ores  of  Tranfylvania  which  contain  tellurium, 

■  •  ih-xk  J  C  a-  after 


37<5  Scientific' Nenvs. 

after  having  once  more  repeated  them,  in  order  to  determine  the  proportions  \vith  more, 
certainty  and  precifion.  The  refearches  of  niineralogifts  and  chemifts  will  foon  inform 
us  whether  tellurium  is  likewlfe  met  with  in  other  places,  or  whether  ature  has  ex- 
Clufively  appropriated  this  metal  to  the  gold  mines  of  Tranfylvania. 


SCIENTIFIC  NEWS,  AND  ACCOUNT  OF  BOOKS. 
American  News. 

JLN  confideration  of  the  general  utility  that  would  refult  from  the  citizens  of  the  United 
States  being  enabled  to  procure,  free  from  expence,  an  analyGs  of  any  ores,  or  mineral  fub-  ' 
fiances,  "The  Chemical  Society  of  Philadelphia,"  on  the  aoth  of  June  1797,  pafled  the  fol- 
lowing Refolution  : 

"  Refolved, 
.  *'  That  a  Committee  of  five  Members  be  appointed,  whofe  bufmefs  it  fiiall  be  to  notify 
in  the  different  papers  of  the  United  States,  and  by  circular  letters,  that  they  will  give  an 
analyfis  of  all  minerals  which  may  be  fent  them." 

In  conformity  to  the  above  refolution,  they  have  given  notice  that  they  will  analyze  any 
mineral  which  may  be  fent  them,  provided  it  be  forwarded  free  of  expence,  Snd  accompa- 
»icd  with  an  account  of  the  place  and  fituation  in  which  it  was  found. 

Committee. 
Thomas  Smith,  No.  19,  North  Fifth  Street. 
James  Woodhoufe,  No.  13,  Cherry  Street. 
Samuel  Cooper,  No.  178,  South  Front  Street, 
Adam  Seybert,  No.  191,  North  Second  Street.- 
John  C.  Otto,  No.  37,  North  Fourth  Street. 


Profeflbr  Barton  of  Philadelphia,  who  has  lately  publifhed  a  fmall  traiSl:  on  the  Vegetable 
Materia  Medica  of  our  country,  is  preparing  for  the  prefj  a  work  to  be  entitled  "  Stric- 
tures on  the  Arrangement  of  the  Materia  Medica,  adopted  by  Dr.  Darwin  in  his 
Zoonomia."  

January  19,  179^-     The  American  Philofophical  Society   held  their  annual  ele£tion  of 
officers  on  the  firft.  Friday  of  this  inftant,  when  the  following  were  doly  choien  :  • 
'     Prefident— The  Hon.  Thomas  Jefferfon. 

Vice-Prefidents— Nicholas  Collin,  D.  D.  Dr.  Benjamin  Rufli,  and  Dr.  Cafpar  Wiftar. 

Treafurer — Mr.  John  Vaughan. 

Secretaries— Samuel  Magaw,  D.  D.  Dr.  Adam  Seybert,  Dr.  J.  C.  James,  and  Mr. 

Sauiuel  H.  Smith. 
Curators— Mr.  Charles  W.  Peale,  Dr.  Benjamin  S.  Barton,  and  Mr.  Robert  Patterfon. 
Clafs  of  Counfellors  for  three   years— Mr.  Jonathan  B.  Smith,  Dr.  William  Currie^ 
William  Smith,  D.  D.  and  Mr.  Jonathdn  Williams,  two  years  from  Janu;iry  1798. 

Ae,R05Tj1TI0N. 


AtnJlatiott.'^Accuuhi  of  Boiis,  377. 

Aerostation, — Augnjl  12,  1798. 

BLANCHARD  afcendcd  into  the  atmofphere,  for  the  forty-fixth  time,  by  means  of  an 
apparatus  confuling  of  five  balloons  attached  to  a  car,  and  a  fixth  fmall  globe.  He  threw 
cut  a  dog  attarheci  to  a  parachute,  which  defcended  gradually,  but  of  wliofe  fate  no  men- 
tion is  made  in  the  Moniteur,  whence  I  extra£t  this  intelligence.  He  rofe  at  half  paft  noon 
from  Rouen,  afcended  to  the  height  of  2500  toifes,  and  landed  again  at  55  minutes  after 
two,  near  the  village  of  Bazancourt,  12  leagues  diftant  from  the  fir(t  place.  We  have  no 
account  of  any  remarkable  obfcrvatlon  made  during  this  voyage,  nor  the  reafons  why  his 
apparatus  was  fo  complicated. 

Cit.  Garnerin,  on  the  28th  ofthe  fame  month,  made  his  eleventh  afcenfion  from  Paris. 
His  couife  for  a  confiderable  time  was  near  the  ground,  during  which  he  converfed  with 
the  people  below.  Thefe  converfations  fhewed  how  much  the  earth  refle£led  found  ;  for 
all  his  words  were  repeated  five  or  fix  times.  He  thought  at  firfl  that  it  might  be  governed, 
by  fome  local  circumftances,  which  indeed  is  very  probable  with  regard  to  the  repetition. 
He  defcended  feveral  times  to  the  fame  level,  at  d  fiances  of  ten  leagues  afunder,  where  he 
conflantly  obferved  the  fame  effeft.  This  great  vibration  of  the  air  was  not  fenfible  to 
diftances  exceeding  150  or  200  toifes.     It  decreafes  with  the  diftance. 

Does  the  vertical  tranfmiffion  of  found  differ  from  that  which  is  made  in  an  horizontal 
dircftion  ?  On  this  head,  however,  may  be  read  the  very  entertaining  account  of  Uavid, 
Frcedlichius,  at  the  end  of  the  19th  chapter  of  the  firfl  book  of  Varenius,  who  afcended 
the  higheft  eminences  of  Carpathas,  near  Kefmarkt,  in  Hungary.  It  is  copied  by  Der- 
ham,  in  the  firfl:  volume  of  his  Phyfico-Theology. 

This  aeronaut  was  accompanied  by  a  female  Citizen,  Henry.  They  rofe  at  25  minutes 
after  four,  and  defcended  at  nine  in  the  evening,  at  the  gates  of  Chalons,  forty  leagues 
from  Paris,  and  thirty-feven  from  the  place  whence  they  departed. 


Effays  Political,  Economical,  and  Philofophical,   by  Benjamin  Count  of  Rumfbrd. 

tffays  Vill.  and  IX. 

THESE  two  EiTays  have  been  before  publiflied  in  the  Philofophical  Tranfa<fiions ;  the 
one  as  long  ago  as  the  years  1786  and  1792,  and  the  other  in  1798.  As  this  laft  is  inferteJ 
in  our  Journal,  Vol.  II.  p.  i«6,  it  will  be  unnecelfary  to  infert  its  contents  in  this  place. 
Both  will  be  highly  acceptable  to  the  poffefibrs  of  the  other  Effays  of  the  Count,  to  complete 
the  collection  of  whick  thefe  were  wanted. 

The  contents  ofthe  eighth  Effay  are,  Chap.  I.  An  Account  ofthe  Inftniments  that  were 
prepared  for  making  the  propofed  Experiments.  A  Thermometer  conftrucftedj  whofe 
bulb  is  furrouiided  by  a  Torricellian  Vacuum.  Heat  is  fou-nd  to  pafs  in  a  Torricellian 
Vacuum  with  greater  difficulty  than  in  Air.  Relative  conducing  Powers  of  a  Torricellian 
Vacuum  and  of  Air  with  regard  to  Heat,  determined  by  Experiment.  Relative  ccHidudting- 
Powers  cf  dcv  Air  and  of  moift  Air.  Relative  conducting  Powers  of  Air  of  different  de- 
grees of  Denfity.  Relative  condudling  Powers  of  Mercury,  Water,  Air,>nd  a^  Torricellian 
Vacuum.— Chap.  II.  The  relative  Warmth  of  various  Subft^ances  ufed  in  making  Artificial 
Clothing,  determined  by  Experiment.    Relative  Warmth  of  Coverings  of  the  fame  Thick- 


57$  Account  of  New  Publication}, 

nefs,  and  formed  of  the  fame  Subftance,  but  of  different  Denfitie?.  Relative  Warmth  of 
Coverings  formed  of  equal  Quantities  of  the  fame  Subftance,  difpofed  in  different  ways. 
Experiments  made  with  a  view  to  determining  how  far  the  Power  which  certain  Bodies 
poffefs  of  confining  Heat  depends  on  their  Chemical  Properties.  Experiments  with  Char- 
coal, with  Lamp-black,  with  Wood-afhes.  Striking  Experiments  with  Semen  Lycopodii. 
All  thefe  Experiments  indicate  that  the  Air,  which  occupies  the  Interflices  of  Subllances- 
iifed  in  forming  Coverings  for  confining  Heat,  a6ls  a  very  important  part  in  that  operation. 
Thofe  Subftances  appear  to  prevent  the  Air  from  conducing  the  Heat.  An  Enquiry  con- 
cerning the  Manner  in  which  this  is  effected.  This  Enquiry  leads  to  a  decifive  Experiment, 
from  the  refult  of  which  it  appears  that  Air  is  a  perfect  Non-condudlor  of  tieat.  Tnis 
Difcovery  affords  the  means  of  explaining  a  Variety  of  interefting  Phenomena  in  th« 
OEconomy  of  Nature. 

Traite  de  la  Sphere  et  du  Calendrier,  par  Rivard,  5me  Edition,  revue  et  augmenteepar 
Jerome  Lalande,  i  vol.  8vo.  avec  Gravures,  a  Paris.  A  Treatife  on  the  Sphere  and 
the  Calendar,  by  Rivard,  revifed  and  augmented  by  Jerome  Lalande,  i  vol.  8vo.  with 
Plates. 

THE  modern  advances  in  Aflronomy  rend  ered  it  necefTary  to  make  fome  alterations  in 
this  Work,  which  poffefTes  a  high  chara£ler  for  Perfpicuity  and  Accuracy.  Cit.  Lalande  has 
correfted  the  Table  of  Latitudes  and  Longitudes,  and  added  a  Chapter  on  Time,  befides 
making  other  Improvements. 

Philofophy  of  Mineralogy.     By  Robert  Townfon,  LL.D.  F.  R.  S.  Edin.     8vo,  219  pages, 

with  three  Engravings. 

THIS  performance  is  the  outline  of  a  larger  work  formerly  announced,  and  intended  to 
have  been  accompanied  by  a  colledtion  of  fofhls,  but  which  did  not  meet  with  the  ex- 
peded  fupport.  It  confifts  of  twelve  chapters.  The  three  firft  contain  an  introdudlion, 
with  an  account  of  the  fimple  elementary  fubftances  of  which  minerals  are  compofed,  and 
the  laws  of  aggregation  and  combination  by  which  they  are  governed.  Thefe  are  followed 
by  an  enumeration  of  compounds,  according  to  Dr.  Babington's  excellent  "  Syflematic 
Arrangement,"  and  four  chapters  refpeftively  treating  upon  Stratification,  the  Irregularities 
of  the  Earth's  Surface,  Veins,  and  Petrifadlions.  The  Author  then  proceeds  to  confider  the 
value  and  ufe  of  the  external  charadters  of  Minerals  ;  and  gives  a  very  ample  terminology, 
confifling  of  the  appellations  in  Englifh,  Latin,  and  German,  with  their  correfpondent  de- 
finitions, under  the  titles  of  Colour,  Figure,  Surface,  Luflre,  Texture,  Struflure,  Fraflure, 
and  Fragments  ;  Tranfparency,  Scratch,  Score,  and  Soiling  ;  Cohefion,  AdheGon,  Sound, 
Feel,  Coldnefs,  Denfity,  Smell,  Tafte,  and  Friability  :  To  which  he  adds  the  Habitudes,  or 
Refults  of  Experiment.  Two  fubfequent  chapters  indicate  the  ufe  of  thefe  terms  in  Claffi- 
fication,  Defcription,  and  Invefligation  ;  with  fhort  Inftruftions  for  colledting  Specimens, 
and  forming  Cabinets.  The  concluding  chapter  contains  a  lift  of  near  three  hundred 
works  on  Mineralogy. 


Proceeding! 


Mr.  Park's  travels  in  Jfricth  37<> 

Proceedings  of  the   Aflbclation  for  promoting  the  Difcovery  in  the  Interior  Parts  of 

Africa,  &c. 

Abftraft  of  Mr.  Park's  Travels.     [Concluded  from  page  332.] 

AFTER  travelling  upwards  of  a  month,  afcending  by  the  fide  of  the  Niger  till  it  ceafed  to 
be  navigable,  he  at  length  funk,  under  his  fatigues,  and  the  difficulties  of  his  enterprife  ;  and 
at  Kamalia,  five  hundred  miles  (hort  of  any  friendly  country,  on  the  Gambia,  he  fell  into  a 
fcvere  and  dangerous  fit  of  ficknc<s>  If  in  this  fituation  had  he  been  able  to  travel,  great 
part  of  his  way  Jay  through  a  defert.  He  had  therefore  no  other  refource  but  to  wait  for 
the  firft  caravan  of  flaves  which  might  travel  the  fame  track.  Such  a  one  was  cxpefted  to 
pafs  through  Kamalia  at  the  end  of  three  months,  and  the  chief  direftor  refided  at  the 
place.  To  hinij  therefore,  Mr.  Park  applied  ;  and  for  the  value  of  one  flave,  to  be  paid  on 
his  fafe  arrival  at  the  Gambia,  this  worthy  negro,  whofe  name  was  Karfa  Taura,  not  only 
undertook  to  conduct  him  fafe  to  Pifania,  but  offered  him  likewife  the  accommodation  of 
his  houfe  until  the  time  of  the  caravan's  departure.  Under  this  man's  roof  our  traveller 
was  confined  to  his  mat  (his  only  bed),  by  a  fevcre  and  dangerous  fever,  for  upwards  of  a 
month.  Five  months  longer  was  he  detained  for  the- caravan.  During  this  long  interval, 
not  a  murmur  efcaped  the  lips  of  Kai  ra,  nor  of  any  of  his  wives,  at  the  trouble  and  expence 
which  their  inmate  brought  upon  them.  To  the  kind  attentions,  the  tender  folicitude,  the 
cheerful  afliduity,  and  flowing  hofpitality,  of  thefe  poor  Pagans,  Mr.  Park  declares  that  he 
is  indebted,  not  only  for  his  fafe  return  to  Great  Britain,  but  alfo  for  the  prefervation  o£ 
his  life  ;  aiwl  he  admits  that  he  made  his  friend  Karfa  but  an  inadequate  return  (though 
the  beft  in  his  power),  by  prefenting  him,  on  their  arrival  at  the  Gambia,  with  double  the 
fum  that  he  had  originally  promifed. 

During  this  long  confinement  of  Mr.  Park,  he  acquired  much  information  refpedling  the 
trade  in  flaves  and  gold-duft,  the  vegetable  producStions  of  Africa,  the  character  of  the  na- 
tives, their  agriculture  and  manufactures,  their  modes  of  living,  manners,  fuperflitions, 
wars,  police,  and  government,  which  have  never  yet  been  competently  defcribed,  and  for 
which  we  muft  wait  for  the  appearance. of  his  work.  In  the  mean  time  it  may  be  re- 
marked, that  though  the  climate  on  the  borders  of  the  defert  is  prodigioufly  hot,  yet  in  the 
fouthern  diftriiSVs,  which  abound  with  wood  and  water,  the  climate  improves,  and  in  the 
mornings  and  evenings  the  air  is  ferene,  temperate  and  pleafant.  Some  of  the  vegetable 
produdts  have  been  noticed.  To  thefe  may  be  added  the  Lotus,  of  ancient  renown,  afford- 
ing a  fmall,  yellow,  farinaceous  berry  about  the  fize  of  an  olive,  which  being  poimded 
in  a  wooden  vefTel,  and  afterwards  dried  in  the  fun,  is  made  into  excellent  cakes  refem- 
bling  the  fweeteR  gingerbread.  JMoft  of  the  edible  roots  of  the  Weft  Indies  are  likewife 
found  here,  together  with  indigo,  cotton  and  tobacco;  but  neither  the  fugar-cane, 
coffee,  cacao,  the  pine-apple,  nor  a  variety  of  other  fruits,  were  feen  by  him,  nor  known  to 
the  natives.  Uncultivated  lands  belong  to  the  ftate  ;  but  in  other  refpedls  landed  property 
is  admitted,  without,  as  it  fhould  appear,  any  particular  feodal  or  other  limitations.  Among 
their  manufaftures  may  be  reckoned,  an  excellent  beer  made  from  corn  -y  the  fabrics  of 
cotton  cloth,  which  are  dyed  with  indigo  ;  the  tanning  of  leather,  which  is  flained  both 
yellow  and  red ;  the  fmelting  of  iron,  though  imperfedly  j,  and  the  calling  and  working  o£ 
gold. 

¥rorafc 


C38.0  Mr.  Park's  Travels  in  Afnc(t;^c. 

From  the  condu(£l  and  cruelty  of  the  wars  between  the  petty  and  independent  dates  qf 
Africa,  it  appears  that  thofe  who  do  not  make  flaves  of  their  captives  put  them  to  death. 
With  regard  to  religion,  the  Mahometans  fhew  much  zeal  in  teaching  the  Negro  children 
to  read,  and  avail  thCmfclves  of  this  means  to  convert  them  from  Paganifm.  Circumcifion, 
(Whidh  is  notorioiifly  more  ancient  and  extenfive  in  its  prevalence  than  the  religion  of  Ma- 
.homet,  is  pra£tifed  alfo  by  the  Negroes,  who  confider  it  rather  as  an  operation  of  phyficil 
than  religious  neceflity.  The  convi(ftion  of  a  future  ftate  of  rewards  and  punifhments  was 
univerfally  prevalent  in  every  diflrlfl  vifited  by  our  traveller. 

In  the  latter  end  of  April  1797,  the  caravan  being  completed,  and  Mr.  Park's  health 
perfe£l:ly  re-eftablifhed,  he  fet  out  from  Kamalia,  in  company  with  feventy  perfons,  of 
whom  thirty-feven  only  were  flaves  for  fale.  On  the  4th  of  June  they  fell  in  with  the 
river  Gambia ;  and  in  fix  days  more,  namely  on  the  loth,  Mr.  Park  had  the  fatisfaiStion  to 
enter  the  hoiife  of  Dr.  Laidley,  from  which  he  had  fet  out  eighteen  months  before.  On 
Uie  isth  of  the  fame  month,  he  embarked  in  a  flave-(hip  for  America  ;  which  being  driven 
By  ftrefs  of  weather  into  the  ifland  of  Antigua,  Mr.  Park  took  his  paffage  from  thence  in 
a  veffel  bound  to  Great  Britain,  and  on  the  25th  of  December  arrived  fafely  in  London. 


*4t*  The  refpedlable  Writer  of  a  Paper  on  the  Secondary  Foci  of  Lenfes,  is  informedi 
that  a  bad  fort  of  concave  Refle£lors  has  long  fince  been  conftru£ted  and  fold  in  London  by 
filvering  one  furface  of  a  convex  lens ;  and  that  it  is  probable  thefe  foci  (which  are  eafdy 
determined  from  the  curvatures  and  refractive  powers)  may  have  been  neglc£led  by  op« 
tical  writers,  becaufe  the  images  are  in  every  cafe  more  dilute  and  indiftindl  than  fuch  as  are 
produced  either  by  refradion,  or  refledion  alone.  That  the  efFed  has  not  been  difregard- 
ed  as  a  fource  of  imperfeftion  in  lenfes,  may  be  feen  by  confulting  our  Journal,  IL  233. 


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i;;;::  3<i 


5| 


JOURNAL 

OP 

NATURAL   PHILOSOPHY,   CHEMISTRY, 

AND 

THE   ARTS. 


DECEMBER     179  8. 


ARTICLE  I. 

Memoir  on  the  Climate  of  Ireland,  By  the  Rev.  WiLLIAM  liAMJirOK,  ofFavet,  in  the 
County  of  Donegal  \  late  Fellow  of  Trinity  Csllege,  Dublin;  M.R.I.  A.  Correfponding  Mem- 
ber of  the  Royal  Society  of  Edinburgh^  tsfc* 

T 

J-T  is  generally  fuppofed  that  the  feafons  in  ouTifland  hare  fuffered  a  confiderable  change, 
almoft  within  the  memory  of  the  prefent  generation.  The  winters  of  our  climate  arc  faid 
to  have  laid  afide  their  ancient  horrors,  and  frequently  to  have  aflumed  the  mildnefs  and 
vegetative  powers  of  fpring ;  while  fummer  is  reprefented  as  lefs  favourable  than  hereto- 
fore,- lefs  genial  in  promoting  vegetation,  and  lefs  vigorous  in  forwarding  the  fruits  of  the 
earth  to  maturity. 

It  is  indeed  true,  that  in  this  inftance  popular  opinion  does  not  ftand  fupported  by  the 
concurrent  tellimony  of  meteorological  obfervatioiis  i  there  .is  no  clear  evidence  derivable 
from  them,  that  the  prefent  feafons  are  materially  different  from  former  ones  j  and  therefore  • 
philofophers  and  meteorologifts  naturally  afcrib^  to  the;  querulous  difpofition  of  the  farmer, 
the  chill  fenfations  of  old  age,  or  the  predlledli^rt  Svhith  every  one  feels  for  the  cheerful  days 
of  childhood,  the  adoption  of  an  opinion  that  feems  fo  eafily  to  flow  from  thefe  fources. 

But  let  it  be  remembered,  that  the  inftruments^of  atmofpherical  obfervations  do  not  ex- 
tend to  alt  the  circumftances  which  influence  tiie  erOpS  of  the  farmer,  or  the  fenfations  of 
the  man.  The  thermometer  may  mark  the  general  temperature  of  our  climate  as  un- 
changeable ;  and  the  pluviometer  may  afcertaifi  its  ufaal  moifture ;  whiift  a  clouded  atmofphere 
or  a  tempeftuous  wind  fhall  mar  the  progreflfive  maturity  of  harveft,  and  ihaiterthe  languid 
frame  of  declining  age.  .:    /^rvj;' 

-■•((       -i^      ''    '.  »  IrUb.Acad.;tfb<^OV-.  .■■  . 

VsoL.n. -Dec  1798.  .3D  <•  Heat 


3^2  -      Ol'firvat'etit  to  prove  «  Change  ef  Qimate  in  Ireland- 

Heat  and  cold  and  rains  are,  indeed,  principals  in  the  economy  of  fcafons ;  but  winds, 
clouds,  vapours,  and  other  circumftances  rarely  reglftered,  often  unperccived,  are  to  be 
deemed  at  lead  ancillary  in  the  extenfive  fyftem  •,  and  may  give  plaufibility  to  popular  fen- 
fations  and  opinions,  even  without  the  aid  of  meteorological  teftimony. 

It  is  the  purpofe  of  this  paper  to  offer  to  the  Academy  fome  obfervations  relating  to  this 
interefting  fubjeft  ;  and  to  mark  a  few  prominent  events  in  the  phenomena  of  our  climate, 
which  may  add  credibility  to  general  report. 

Of  the  Winds,  and  their  EffeBs. 

THE  winds  which  mod  ufuaily  prevail  in  our  latitudes  blow  from  the  weftward,  for  rea- 
fons  unnecefliiry  to  be  detailed  here.  Thefe  winds  are  commonly  mild  in  their  tempera- 
ture, and  molft  in  their  nature.  They  are  from  thefe  properties  extremely  friendly  to  ani- 
mal and  vegetable  life ;  and  to  them  the  great  population  of  Ireland,  and  the  uncommon 
fertility  of  its  foil,  may  among  natural  caufes  be  afcribed. 

Rut  from  whatever  circumftances  it  has  arifen,  thefe  winds  have  of  late  years  fwept  with 
unrcMnmon  violence  over  the  furface  of  our  ifland  ;  fruflrating  the  ufual  efFe6ls  of  their  ge- 
nial properties  by  the  overbearing  fury  of  their  courfe ;  and,  like  Saturn,  fometimes  devouring 
the  offspring  to  which  themfelves  had  given  birth. 

Why  tliefe  wefterly  winds  have  ceafed  to  bear  the  charafter  of  zephyrs  may  admit  of 
much  curious  and  interefting  inveftigation :  at  prefent  I  ftiall  be  fatisfied  with  endeavour- 
ing to  eftablifh  the  fadl  itfelf,  by  fuggefting  to  the  Academy  fome  circumftances  that  feem 
to  determine  the  matter  with  a  very  great  degree  of  probability. 

The  effeds  of  thefe  winds  are  marked  in  vifible  chara£lers  over  the  whole  furface  of  the 
kingdom ;  but  they  are  peculiarly  diftinguiftiable  in  the  northern  province  of  Ulfter ;  and 
chiefly  in  the  extreme  countries  of  that  province,  where  a  northerly  latitude,  joined  to  an  ex- 
pofed  fituation  on  the  coafts  of  the  ocean,  forms  an  apt  ftation.for  obfervations,  and  exhibits 
as  it  were  on  a  magnified  fcale  the  degrees  of  the  phenomena  themfelves. 

Three  natural  regifters  of-  thefe  effeds  have  come  within  my  obfervation  -,  the  trees  of 
the  country,  the  fands  of  the  fea-coaft,  and  the  tides  of  the  ocean  :  of  each  of  thefe  I  ihall 
■make  mention  in  its  order. 

Of  the  Trees. 

IT  is  a  fa£l  extremely  well  eftabliftied,  that  the  pine-tree,  peculiarly  that  fpecies  vulgarly 
denominated  the  Scotch  fir,  formerly  grew  on  many  of  the  mountains  of  this  kingdom,  and 
on  parts  of  the  northern  and  weftern  coafts,  exceedingly  bare  and  open  to  ftorms.  Vaft 
roots  and  noble  trunks  of  this  fpecies  6f  pine  have  been  feen  and  examined  by  me  with  at- 
tention, in  fituations  where  human  induftry  cannot  now  rear  a  twig  of  the  hardieft  tree.  • 
Qn  the  higheft  lands  of  the  general  furface  of  th&  kingdom,  in  the  county  of  Weftmeath, 
amid  the  mountains  of  the, county  of  Antrim, .and  on  theriaked  coafts  of  Enifliowcn  and 
Roffes,  in  the  county  of  Donegal,  pine-trees  have  formerly  arrived  at  an  age  of  an  hundred 
and  twenty  years,  have  grown  to.  the  fi^  of  .a  yard  in  diameter,  and  furpaffed  fifty  feet  in 
height.     :'.^'r.-y.  kIi-Hc  vr-rrr.-;:;!  tvri:  i- 1^-:  r  ei')  ::. 

There  is  great  reafon  to  think  that  two  centuries  have  hardly  elapfed  fince  many  of  thefe 

trees  grew  in  thofe  fituations ;  and  prob«J)le  rsaJ[onSi  might  be  adduced  to  limit  the  great  pe- 

-  r  ii  liod 


Ohferuatmt  to  pftvf  a  Change  of  Climate  in  Ireland.  38  J 

Hod  of  their  defl:ru£lion  to  the  age  of  James  the  firft  of  England.  In  fhofe  reigns,  rewards 
^wcre  held  out  for  fettling  the  kingdom,  and  clearing  its  furface  of  forefts,  which  under  fa- 
vour of  inceffant  wars  and  negleded  tillage,  during  a  period  of  eight  centuries,  had  over- 
fpread  the  face  of  the  country*. 

The  harfti  and  furrowed  bark  of  this  pine  has  occurred  to  me  in  fuch  a  perfeft  ftatc  of 
prefervation  as  almoft  alone  to  determine  its  fpeciesf. 

The  cones  have  been  found  by  me  at  a  depth  of  many  feet  from  the  furface  of  the  earth, 
in  fuch  condition  as  almoft  to  give  hope  of  raifing  plants  from  their  feed  J.  Marks  of  the 
woodman's  hatchet  on  their  trunks ;  veftiges  of  fire  applied  for  their  deftruftion  ;  and  pieces 
of  charcoal  into  which  many  of  them  have  been  burnt  §  -,  palelngs  and  fmall  enclofurcs  found 
at  the  level  where  they  have  formerly  grown  1]. 

Leathern  flioes,  wooden  veffels  filled  with  butter  and  other  light  fubftanccs  found  at  con- 
fiderable  depths  In  turf  bogs**,  and  not  likely  to  have  defcended  through  the  matted  texture 
of  that  fubftance,  give  additional  teftimony  to  the  opinion  that  the  exiftence  of  thefe  bogs, 
and  of  courfe  that  of  the  trees  which  they  contain,  is  not  of  an  extremely  ancient  date. 

It  is  necdlefs  to  recall  the  attention  of  the  Academy  to  the  difficulty  of  raifing  trees,  at 
prefent,  in  many  of  thofe  fituatlons  where  the  ancient  pine  and  oak  of  Ireland  have  within 
the  period  of  human  exiftence  flouriflied  with  luxuriance. 

The  labours  of  the  farmer,  the  refources  of  wealth  and  information,  the  rewards  of 
patriotic  focletles,  and  even  the  liberal  encouragement  of  the  leglflaturc  itfelf,  have  in  vain 
ftruggled  againft  the  weftern  ftorms during  the  latter  part  of  the  prefent  century;  and  the 
planters  of  our  age,  wearied  with  combating  the  tempeft,  have  generally  found  it  neceflary 
to  fly  from  all  elevated  and  expofed  fituatlons,  and  to  abandon  the  pleafing  idea  of  covering 
the  nakedncfs  of  mountains,  the  fterillty  of  rocks,  and  the  bleak  uniformity  of  bogs,  with 
the  luxuriant  foliage  of  the  oak  and  the  pine. 

Of  all  the  foreft  trees  which  in  later  times  have  been  cultivated  for  general  ufe,  there  is 
none  higher  in  the  eftimation  of  our  farmers  than  the  afli.  It  is  a  tree  which  buds  late,  but 
finally  ifiucs  forth  ftrong  and  fucculent  Ihoots :  fecure  by  its  deciduous  nature  from  wintry 
hlafts,  it  is  neverthelefs  extremely  fenfible  to  the  efforts  of  fummcr  ftorms ;  and  becomes 

•  "  In  this  reign  ipe-ftaves  was  one  of  the  ordinary  exports  of  Ireland ;  fo  that  a  mighty  trade  was  driven 
with  them,  and  thoufands  of  trees  ^frere  felled  every  year  for  this  piirpofe.  A  multitude  of  iron-mills  were 
erefted;  and  it  is  incredible  how  much  charcoal  a  fingle  iron-mill  will  confume  in  one  year.  So  that  all  the 
oreat  woods  which  the  maps  flicw  us,  on  the  mountains  between  Dundalk  and  Newry,  are  quile  vaniflied,  ex- 
cept one  tree  clofc  to  the  highway,  at  the  very  top  of  the  mountain,  which,  as  it  may  be  fcen  a  great  way  oft, 
therefore  ferveth  travellers  for  a  mark.'' 

«'  Yet  there  are  ftill  great  woods  remaining  in  Dunnagall,  in  Tyrone,  in  Antrim,  &c."  See  Nat.  Hift.  of 
Ireland,  by  Boates,  Molleneux,  and  others,  written  about  tlie  middle  of  the  laft  century. 

■(•  In  Bracknaiwevlin  bog,  county  of  Weftmeath. 

%  In  Lackbcg  oog,  near  Rutland,  county  of  Donegal.  ; 

§  Found  in  k  bog  in  the  liberties  of  the  city  of  Londonderry. 

II  In  a  bog  near  Surock,  county  of  Weftmeath;  near  Kilrulh,  couaty  of  Clare;  at  Carnilk,  near  Ramelton, 
county  of  Donegal. 

*'*  Omitting  other  inftances,  two  wooden  veffels  containing  butter  were  very  lately  found  deep  in  a  turf  hog, 
in  the  Fews  Mountains,  near  Ballymoire,  the  feat  of  Sir  Walter  Synnott.  The  veffels  were  extremely  inartlfi- 
-«ial,  being  little  better  than  the  hollow  trunks  of  fome  large  fpecies  of  willow :  the  butter  was  infipid,  inodo- 
rous, colo\irlefs,  fomewhat  refembling  unftuous  white  fteatitcs  in  its  touch  and  appearance;  but  its  inflamma- 
*ility  remained  fo  perfcft,  as  to  admit  «f  its  being  made  into  candles,  to  which  ufe  much  of  it  was  applied. 

3  D  2  a  faithful 


gt4  '    DeJIraR'wn  ef  Corporate  Toivn  tf  BanneiVy  and 

z  faithful  reg'iftet  ot  the  winds  of  our  climate,  marking  their  mpft  prevalent  direction  by 
the  inclination  of  its  boughs,  and  their  violence,  by  the  degree  wherein  its  tender  flioots 
or  more  mature  branches  are  withered  or  blafted. 

Half  a  century  has  fcarce  elapfed  fince  this  ufeful  fpecies  of  tree  was  generally  planted, 
and  grew  luxuriantly  iii  every  part  of  Ireland :  yet  are  there  hardly  any  expofed  places  in 
the  kingdom  where  its  top  branches  do  not  now  in  one  part  or  another  exhibit  the  withered 
veftigcs  of  commencing  decay.  Through  many  parts  of  Ulfter  it  is  a  blafted  tree  ;  and  in 
all  unftteltered  fituations  in  the  three  northern  counties  of  Antrim,  Derry,  and  Donegal, 
the  fpecies  feems  faft  verging  toward  annihilation*. 

Attentive  to  each  progno'lic  of  the  feafons,  alive  to  every  circumftance  whereon  the  fu- 
ture fubfiftence  of  his  numerous  family  in  a  populous  country  may  depend,  the  farmer  of 
the  north  fees  thefe  veftiges  of  the  tempeft  with  folicitude  ;  and  often  taught  of  late  to  dread 
the  effects  of  fummer  ftorms  on  his  luxariant  crops  of  potatoes,  he  has  become  querulous 
from  experience,  and  thinks  he  has  fome  reafon  to  complain  that  the  feafons  are  lefs  fa- 
vourable to  his  hopes  than  formerly ;  that  the  pine-tree  has  not  forfaken  the  mountains,  nor 
the  afli  been  blalted  in  his  fields,  without  the  influence  of  increafing  tempefts. 

Of  the  Sands. 

THE  wafle  and  dreary  folitude  ef  extended  barren  fands  which  almoft  every  fea-coaft  ex- 
hibits, is  generally  paffed  over  with  rapidity,  as  ufelefs  to  the  philofopher  from  the  in- 
calculable fluduation  of  its  furface,  and  wearifome  to  the  traveller  by  its  difgufting  uni- 
formity. 

Yet,  in  the  mldft  of  fucb  a  fterile  fcene,  where  nothing  occurs  to  divert  the  path  or  diC- 
trad  the  penfive  mind  of  the  traveller,  if  traces  of  human  exi!lence  fliould  fuddenly  become 
vifible  ;  if  enclofures  fhould  appear,  to  mark  the  cheerful  Hre-fide  of  fome  former  villager, 
or  the  circuit  of  his  little  garden }  if  embattled  walls  or  maxble  piers  Ihould  ftart  up  amid 
the  fands,  fuggefting  ideas  of  ancient  elegance  and  felUvity ;  he  muft  have  a  Stoic's  mind, 
indeed,  who  will  not  venture  to  calculate  caufes,  and  feel  intereiled  in  events,  that  come 
home  fo  clofely  to  the  human  heart. 

On  many  parts  of  the  coaft  of  Ireland  fcenes  fuch  as  thefe  may  be  difcovered. 

At  the  entrance  of  the  river  Bannow,  in  the  celebrated  barony  of  Forth  in  the  county 
of  Wexford,  veftiges  of  ruins,  traced  with  difliculty  amid  the  heaps  of  barren  fand,  ferve 
to  afcertain  the  fite  of  a  town,  whofe  ancient  refpeiflability  was  marked  by  the  royal  charter, 
which  endowed  it  with  the  privilege  of  fending  reprefentatives  to  the  parliament  of  the 
nation,  and  whofe  opulence  may  be  inferred  from  the  ftreets  which  arc  regiftered  in  the  re- 
venue records  of  the  laft  century  f . 

•  In  Lancafliire,  in  England,  between  Garftang  and  Prefton,  the  trees  are  alfo  cut  offby  the  wefterly  winds,. 
See  Newte's  Tour,  year  1791. 

f.  "  So  late  as  the  year  1626,  Bannow  is  regiftered  in  the  cuftom-boufe  books  of  Wexford,  as  having  four 
ftreets  which  paid  quit-rent  to  the  crown,  viz.  Lady-ftreet,  High-ftreet,  Weavers-ftreet,  Little-ftreet,  and  fome 
build  ngs  furrounding  the  church.  The  only  remains  of  Bannow  which  ftand  vifible  at  this  day  (1786)  are 
Ae  walls  of  its  church.  There  is  not  on  or  near  the  town  but  one  poor  folitary  hut.  The  ele£lion  for  the  re- 
prefentatives of  the  town  is  held  on  the  walls  of  an  old  chimney  adjoining  to  the  church,  which  tumbled  dowa 
ficce-meal,  and  forms  the  council-table  of  that  ancient  and  loyal  corporation.'' 

private  Utter  of  a  FrienUin  iba  County  of  Wexford. 

Amid!' 


tie  Mtit'fton-houfi  of  the  Boyne  Family,  ly  drifted  Sand,  Ufc.  3S5 

Amid  the  fands  between  Portrufii  and  Dunluce,  in  the  county  of  Antrim,  in  the  year 
1783,  the  ruins  of  a  villag.e  might  be  feen  deferted  by  its  inhabitants,  who  had  been  obli- 
ged to  move  furtlier  into  the  country. 

In  the  year  1787,  the  pcninfula  of  J-Iornhead,  in  the  county  of  Donegal,  contained  vef- 
tiges  of  enclofures  fo  fmall  and  fo  numerous  as  to  mark  the  refidence  of  a  confiderabic 
number  of  human  families,  in  a  fpot  which  exhibited  nothing  but 
-^— —  *'  a  defert,  fait  and  bare, 
"  The  haunt  of  I'eals  and  ores,  and  fea-mews  clang."         Milton. 

Somewhat  about  a  century  ago,  the  peninfula  of  RoITgull,  lying  between  the  harbours 
of  Sheep-haven  and  Mulroy,  in  the  county  of  Donegal,  was  feleded  as  the  refidence  of 
one  of  the  noble  families  of  Hamilton,  titled  Boyne.  It  is  to  be  prefamed  there  was  then 
but  little  apprehenfion,  that  the  elegant  edifice  of  that  age  fhould,  after  the  fhort  interval 
of  an  hundred  years,  (land,  like  Tadmor  of  the  Eaft,  the  folitary  wonder  of  a  furround- 
ing  defert. 

For  the  age  wherein  it  was  built,  and  the  ftyle  of  architetfture  of  that  day,  the  man- 
Con  of  Rofeapenna  may  be  called  elegant.  The  approach  was  from  a  level  green  on  the: 
fliore,  through  a  fuccelTion  of  embattled  courts  and  hanging  terraces,  rifing  in  order  one 
above  the  other,  and  adorned  with  marble  piers  of  no  mean  defign  and  workmanfhip, 

The  rear  was  ornamented  with  gardens  laid  out  and  planted  in  the  fafhion  of  the  laft 
century ;  and  the  parks  and  fields  of  the  demefne  feem  to  have  been  well  divided  and 
enclofed. 

At  prefent,  every  objeft  in  this  place  prefents  to  view  peculiar  charaflers  of  defolation. 
The  gardens  are  totally  denuded  of  trees  and  (hrubs,  by  the  fury  of  the  weftern  winds  r 
their  walls,  unable  to  fuffain  the  mafs  of  overbearing  fands,  have  bent  before  the  accumu- 
lated preflure,  and,  overthrown  in  numberlefs  places,  have  given  free  paflage  to  this  reft- 
lefs  enemy  to  all  fertility.  The  courts,  the  flights  of  fteps,  the  terraces,  are  all  involved 
in  equal  ruin,  and  their  limits  only  difcoverable  by  tops  of  embattled  walls  vifible  amid 
hills  of  fand. 

The  manfion  itfelf,  yielding  to  the  unconquerable  fury  of  the  temped,  approaches  fad  ta 
deftruftion  :  the  freighted  whirlwind,  howling  through  every  avenue  and  crevice,  bears 
IncelTantly  along  its  drifted  burthen,  which  has  already  filled  the  lower  apartments  of  the 
building,  and  begins  now  to  rife  above  the  once  elevated  threlholds.  Fields,  fences,  vil- 
lages, involved  in  common  defolation,  are  reduced  to  one  undiftlnguilhable  fcens  of  flerile- 
uniformity  ;  and  twelve  hundred  acres  of  land  are  faid  thus  to  have  been  buried  within  a^ 
fliort  period  in  irrecoverable  ruin  *. 

Hence 

•  It  would  be  teafing  to  dwell  on  a  repetition  of  fimilar  examples.  I  (hall  juft  mention  two  others :  —  In  a 
fummer  excurfion  from  College  in  the  year  1787,  pafling  from  Dunfanaghy  to  Rutland,  along  the  weftern  coaft 
cf  Donegal,  I  had  great  difficulty  to  difcover  a  houfe  fituated  between  the  river  Guidore  and  the  RoITes  iflands, 
whither  I  had  been  direfted  to  enquire  for  a  guide  ;  and  after  much  fearch  at  length  perceived  its  roof  juft  emerg- 
ing from  the  fands.  The  owner  told  me  that  his  houfe  was  not  long  built,  and  had  at  lirft  a  confiderable  traft  of 
pafture  ground  between  it  and  the  fea-ihore  ;  but  that  of  late  he  was  every  year  obliged  with  great  labour  to  dig; 
if  out  of  the  encroaching  fands,  and  purpofed  (hortly  to  remove  it  to  the  oppofite  fliore  of  a  lake,  called  Mal-- 
lochdearg,  which  lay  behind  the  houfe,  iu  defpair  of  being  able  to  maintain  his  prefent  fituation. 

Adifputed. 


j85  Change  of  CUmaU  In  Ireland, 

Hence  it  appears,  that  interefting  natural  events,  the  confequcnce  of  ftorms,  have  occur- 
red on  our  coafts  in  the  latter  part  of  the  prefent  century,  which  were  not  forefecn,   nor 
1  even  fufpefted,  at  its  commencement. 

Of  the  Tides. 

IT  cannot  be  wondered  at  if  thefe  tempefts  (hould  have  had  confiderable  effe£l  on  the 
iides  of  the  ocean.  The  waters  of  that  element,  as  long  as  they  are  unimpeded  by  extra- 
neous caufes,  obey  the  influence  of  the  heavenly  luminaries,  and  ebb  and  flow  with  degrees 
of  quantity  and  regularity  of  periods  which  come  within  the  reach  of  human  calculation. 
But,  when  they  are  agitated  by  ftorms  or  other  violent  convulfions,  their  quantities  and 
periods  become  altogether  uncertain  and  incalculable. 

Generally  fpeaking,  agitation  of  the  ocean,  from  whatever  caufe  it  may  arlfe,  produces 
increafe  in  the  influx  and  reflux  of  its  tides,  as  well  as  deviation  from  their  calculated  times; 
and  where  the  movement  of  this  extraneous  influence  coincides  with  the  natural  diredlion 
of  the  waters,  the  efFeds  are  vifibly  diftinguifliable  by  the  traces  of  inundation  which  at- 
tend their  unufual  progrefs. 

As  the  tides  of  our  coaft  raifed  in  the  Atlantic  ocean  flow  in  upon  us  from  the  weft- 
ward,  a  ftorm  from  that  quarter  invariably  gives  them  an  uncommon  elevation  in  our  har- 
bours i  and  this  accumulation  of  waters  fometimes  anticipates  the  tempeft  itfelf,  becoming 
the  forerunner  and  prognoftic  of  its  diftant  commencement  and  approaching  impetuofity. 

Of  late  years  thefe  extraordinary  influxes  of  the  ocean  have  been  much  greater  and  more 
frequent  than  formerly.  Every  perfon  on  ourcoafts,  whofe  fituationhas  made  the  conftruc- 
tion  or  prefervation  of  embankments  againft  them  neceflary,  knows,  by  painful  experience, 
how  much  his  labours  have  of  late  years  Increafed,  and  how  impotent  works  formerly 
<fFe£lual  are  now  found  to  be  in  repelling  the  increafing  tides  of  the  prefent  day.  Public 
roads  encroached  on  ;  walls  beaten  down  ;  ftrands  lefs  paflable  than  heretofore ;  meadovr 
and  tillage  land  oftener  and  more  deeply  inundated  j  all  concur  to  prove  increafing  tides 
and  frequency  of  ftorms  on  our  coafts. 

Thefe  phenomena  faithfully  regiftered,  extenfively  and  diftin£lly  delineated  in  natural 
chara£lers,  independent  of  every  bias  from  human  fyftem  or  prejudice,  free  from  the  un- 
certainty of  cafual  records  or  the  locality  of  peculiar  ftations  for  obfervation,  feem  direflly 
to  demonftrate  an  unufual  and  increafing  violence  in  the  winds  of  our  climate  during  the 
prefent  century.  That  thefe  tempefts  have  chiefly  borne  upon  us  from  the  weftward  is 
plain,  from  the  fame  general  appearances :  for,  where  local  circumftances  have  not  direclly 
interfered  in  oppofition,  the  trees,  fhrinking  before  the  preflure  from  the  ocean,  have  uni- 
verfally  yielded  to  the  weftern  blaft.  The  fands  have  drifted,  and  the  tides  rufhed  upon  us 
from  the  fame  quarter,  evidently  demonftrating  the  more  frequent  recurrence  and  fupcrior 

potency  of  the  Atlantic  ftorms. 

[To  be  continued.] 

A  difputed  boundary  in  Favet,  on  the  northern  coaft  of  the  fame  country,  between  the  tenants  of  one  of  my 
own  glebes  and  the  neighbouring  peafants,  is  afcertained  by  a  heap  of  iron  fcorise  in  the  midft  of  loofe  and 
fliifting  fands.  Thirty  or  forty  years  ago,  there  flood  here  the  forge  of  the  village  ;  but  no  remains  of  it,  or 
its  fmith,  are  now  difcoverable,  except  the  cinders  of  the  forge,  and  the  rank  weeds  that  fpring  from  a  rich 
flLratum  of  earth,  once  the  foil  of  his  garden,  and  ftill  yifiblc  in  a  hillock  of  fand, 

11.  Anal;jfu 


Hlflori  efthe  Stlerlan  Red  Ltad,  387 

II. 

Anahfti  of  the  Red  Lead  of  Liberia ;  "with  Experiments  on  the  new  Metal  it  contains.   By  Citizen 

Vav^ELIN,  Infpellor  of  Ores*,  and  Confervator  of  Chemical  ProduSls  at  the  Miner alo^ 

gical  School  f . 

In  ardlum  coaftaTcrum  naturae  majeftas.     Plin, 

SECTION  l,—Hi/iorical  FaBs. 

HE  foffll  known  by  the  name  of  red  lead  was  difcovered  in  1770,  by  M.Pallas,  ifl 
the  gold-mine  of  Berefof,  nearEcatherlneburg  in  Siberia,  in  the  form  of  four-fided  prlfms^ 
■with  or  without  pyramidal  terminations,  of  a  beautiful  orange  red,  commonly  fixed  in  4 
quartzofe  matrix,  to  which  they  fo  ftrongly  adhere  as  not  to  be  detached  without  difficulty. 

All  the  fpecimens  of  this  fubftance  which  are  to  be  found  in  the  feveral  mineralogical 
cabinets  in  Europe^were  obtained  from  this  gold-mine  ;  which  indicates,  that  it  was  for- 
merly abundant ;  but  it  is  fald,  that  for  fome  years  paft  it  has  become  very  fcarce,  and  that 
at  prefent  it  is  bought  for  its  weight  in  gold,  efpecially  if  pure  and  regularly  formed.    The 
fpecimens  which  do  not  poflefs  the  regular  figure,  or  are  broken  into  fragments,  are  approi 
priated  to  painting,  in  which  art  this  fubftance  is  of  high  value  for  its  beautiful  orange  yel- 
low colour,  its  unchangeablenefs  in  the  air,  and  the  facility  with  which  it  can  be  levigated 
with  oil.    The  following  are  the  expreffions  of  M.  Pallas,  who  fpeaks  of  this  mineral,  in  his 
Travels  in  the  year  1770,  under  the  article  of  the  Gold-mine  of  Pifchminlkoi,  tom.  ii. 
page  235  : — "  A  very  remarkable  red  ore  of  lead  is  likewife  worked  at  this  place,  which 
has  not  yet  been  found  in  any  other  mine  of  the  empire,  nor  elfewhere.     This  ore  of  lead 
is  weighty,  of  various  colours ;  fometimes  of  a  cinnabar  red,  and  femi-tranfparent-     It  is 
fixed  in  long  or  fliort  cryftals  in  the  clefts  of  quartz,  and  alfo  in  the  bed  of  the  mine,  which 
is  a  fand-ftone.    It  very  frequently  poflefles,  and  every  where  when  the  fpace  permits,  the 
fame  thicknefs  and  prifmatic  form,  with  four  plane  faces  and  two  extremities  irregularly 
truncated.     It  is  likewife  found  in  fmall  irregular  contorted  pyramids  attached  to  quartz, 
and  refembling  fmall  rubies.    By  reducing  it  to  powder  it  affords  a  beautiful  guhr  of  a  deep 
yellow  colour,  which  may  be  ufed  in  miniature  painting.    In  all  the  eflays  of  this  lead  ore 
in  the  laboratories  of  Ecatherineburg   a  fmall  portion  of  filver  has  been  obtained.    It  pro- 
duces more  than  half  its  weight  (valeur)  in  lead.     Mr.  Lehman  could  not  alcertain  whe- 
ther this  bley-fpath  did  or  did  not  contain  filver,  becaufe  his  experiments  were  made  on 
too  fmall  a  fcale  to  render  that  metal  perceptible.     It  is  difficult  at  prefent  to  procure  the 
neceflary  quantity  for  trials   in  great,  becaufe  the  miners  do  not  often  work  in  the  place 
where  this  ore  is  found,  for  want  of  air.     In  the  mixed  gangues  of  quartz  in  which  thi» 
rare  and  curious  mineral  is  formed,  there  are  found  fmall  cryftals  pointed  at  each  end,  and 
of  the  colour  of  fulphur.     They  refemble  native  fulphur,  and  are  confidered  as  fuch  by  the 
miners  ■,  but  they  do  not  burn  in  the  fire,  nor  decrepitate  before  the  flame,  like  the  ore  of 
lead.  This  may,  perhaps,  be  a  metallic  fpar ;  but  it  is  difficult  to  procure  the  quantity- ne- 

*  Des  nuines. 

+  L'Ecole  des  Mines.— This  Memoir  is  tranflated  from  the  Journal  dej  Mines,  No.  xxxiv,  page  737. 

ceJarf 


2it  -  Htjory  and  Attaints  of  the  Siberian  Red  Lead. 

cefiary  for  exarmnacion.    Thefe  fmall  cryflals  arc  found  on  the  fand-ftone  as  wetl  as  on  tKe 
quartz. 

"  I  can  give  no  other  detail  refpe(3:ing  thefe  minerals,  which  will  not  fpeedily  be  ex- 
haufted  in  this  country,  unlefs  the  veins  fliould  extend  themfelves  to  a  great  depth." 

SECTION    IL 

Account  of  the  Experiments  formerly  made  on  the  Siberian  Red  Lead. 
THE  beautiful  red  colour,  tranfparency,  and  cryflalline  figure,  of  the  Siberian  red  lead 
foon  induced  mineralogifts  and  chemifts  to  make  enquiries  into,  its  nature.  The  place 
of  its  difcovery,  its  fpecific  gravity,  and  the  lead  ore  which  accompanies  it,  produced  an 
immediate  fufpicion  of  the  prefence  of  that  metal ;  but,  as  lead  had  never  been  found  in 
poflclTion  of  the  charadleriftic  properties  of  this  Siberian  ore,  they  thought,  withjuftice, 
that  it  was  mineralized  by  fome  other  fubftance ;  and  Lehman,  who  fivft  fubjefted  it  to 
chemical  analyfis,  aflerted,  in  a  Latin  differtation  printed  at  Peterfburgh  in  1766  (I  fup- 
pofe  1786),  that  the  mineralifers  were  arfenic  and  fulphur. 

In  1789  Citizen  Maquart  undertook  a.  long  courfe  of  experiments,  in  which  I  had  the 
advantage  to  participate,  as  he  has  been  pleafed  to  mention  in -the  introduftion  to  his  work 
entitled  EJfais  de  Mineralogie  du  Nord.  The  objeft  of  thefe  experiments  was  to  determine 
the  nature  of  the  mineralifer  of  red  lead.  We  fought  in  vain  for  the  prefence  of  arfenic; 
but,  by  an  error,  arifing  from  the  ftatc  of  chemical  knowledge  at  that  time,  we  con- 
sidered the  red  lead  ore  as  a  combination  of  fuper-oxygenated  lead,  iron  and  alumine. 

Since  that  time  Bindheim  affirmed,  that  he  had  found  it  to  contain  molybdic  acid,  iron, 
flickel,  cobalt,  and  copper. 

From  the  confideration  of  thefe  refults,  fo  diametrically  oppofite  to  each  other,  and  under 
the  encouraging  confideration  of  the  immenfe  progrefs  of  chemical  fcience  fincc  the  reno- 
vation of  its  language  and  the  re£lification  of  its  theory,  and  venturing  likewife  to  place 
fome  dependance  on  the  flight  experience  I  have  acquired  in  the  art  of  eflaying  fince  I  had 
the  advantage  of  belonging  to  the  eftablifhment  of  mines,  I  thought  proper  to  fubmit  this 
fubllance  to  a  new  examination.  My  labours  have  not  been  without  their  recompcnfe  ; 
and  I  hope  to  prove,  in  the  following  paragraphs,  that  all  which  has  hitherto  been  aflerted 
with  regard  to  the  mineralifer  of  the  Siberian  red  lead  is  entirely  deftitute  of  foundation  ; 
that  it  contains  neither  arfenic,  as  Lehman  pretended  ;  nor  the  molybdic  acid,  and  the  three 
or  four  metals,  announced  by  Bindheim;  nor  iron  nor  clay,  as  Maquart  and  myfelf  ima- 
gined ;  but  a  new  metal,  poflbffing  properties  entirely  unlike  thofe  of  any  other  metal. 

SECTION   m. 

The  new  Methods  of  Analyfis  applied  to  the  Red  Lead  of  Siberia. 
THE  fcience  of  chemiftry  is  at  prefent  founded  upon  principles  fo  certain,  that,  when  tlie 
operator  has  reafon  to  form  a  prefumption  refpe<Sting  the  nature  of  a  compound  body,  it  is 
poihble  tadifcover,  by  mere  indu6lion,  the  rneans  which  are  mod  likely  to  feparate  its  ele- 
ments. Thus,  from  the  fufpicion  that  an  acid  might  exift  in  the  compofition  of  the  red 
Jead,  I  concluded  that  1  might  dccompofe  it  in  the  way  of  double  affinity ;  and  the  rcfult 
of  my  experiments -con-firms  the  indications  of  theory.  ' 

The 


ITfW  Metallic  Acid  in  Siierian  Red  Lead,  08* 

■^  .      :■  -  The  firjl  Method. 

Experiment  I. —^100  parts  of  this  mineral  reduced  to  a  fine  powder  were  mixed  with 
300  parts  of  faturated  carbonate  of  potafli ;  and  this  mixture,  together  with  about  4000 
parts  of  water,  was  boiled  for  an  hour,  I  obferved  that,- 1.  as  foon  as  the  re-a£lion  of  the 
principles  began,  a  ftrong  efFervefcence  was  produced,  which  lafted  for  a  long  time  ;  2.  the 
orange  colour  of  the  lead  became  a  briclcduft  red ;  3.  at  a  certain  period  the  whole  ap- 
peared to  be  in  folution  ;  4.  in  proportion  as.  the  efFervefcence  proceeded,  a  coarfe  powder 
of  a  dirty  yellow  colour  was  thrown  down ;  5,  and  laftly,  the  fluid  affiimed  a  very  fine 
golden  yellow  colour. 

As  foon  as  the  effervefcence  had  entirely  ccafed,  and  the  re-adlion  appeared  to  have  tcr- 
'^minated,  the  fluid  was  filtered,  and  the  metallic  powder  collcifled.     After  wafhing  and 
■;drying,  it  was  found  to  weigh  only   78  parts ;  the   potafh  had  therefore  taken  up  22 
parts.;  .'.^.j  ^Lo.'^-.u ..._ 

Experiment  2. — Upon  the  78  parts  laft  mentioned  I  poured  nitric  acid  diluted  with 
12  parts  of  water.  A  ftrong  effervefcence  followed  ;  the  greateft  part  of  the  matter  was 
diflblved  ;  the  fluid  did  not  acquire  any  colour  ;  and  the  undi^blved  refidue  confifted  of  a 
frnall  quantity  of  lemon-colpured  powder.  I  feparatcd  the  fluid  part  from  the  refidue  by 
means  of  a  fyphon,  waftied  the  remaining  powder  feVeral  times,  and  added  the  waters  to 
the  former  folvent.  The  refidue,  when  dried,  weighed  ottly  14  parts ;  whence  it  foUowsj 
that  the  nitric  afcid  had  diflblved  64  parts.    "' '-^■'  "    '  <"    •'    ; 

Experiment  3.— I  again  mixed  thefe  14  parts  with  42  parts  of  carbonate  of  potafli,  and 
the  requifite  quantity  of  water.  Thefe  being  treated  as  before,  afibrded  the  fame  pheno'- 
mena.  After  filtration  of  the  liquid,  it  was  added  to  the  firft  folution.  The  refidue,  waflied 
and  dried,  weighed  i  parts.     It  was  red  lead,  and  was  iiegle£ted. 

Experiment  4. — ^The  two  nitric  folutions  put  togethei'  and  evaporated  afibrded  92  parts 
of  nitrate  of  lead,  cryftallifed  in  oflahedrons,  pcrfeftly  white  and  tranfparent.     : 

Thefe  92  parts  of  nitrate  of  lead  diftblved  in  water  were  precipitated  by  a  folution  of 
fulphate  of  foda.  The  produd  was  81  parts  of  fulphate  of  lead,  which  anfwerto  56,68  of 
metallic  lead. 

£*/im«^«^  5  .—Tne  alkaline  folutions,  which  were  of  an  orange-yellow  colour,  were 
put  together.  In  the  courfe  of  feveral  days  they  depofited  two  parts  of  a  yellow  powdet 
which  did  riot  contain  lead.  Thefe  folutions,  evaporated  till  a  pellicle  was  formed  on  the 
furface,  afforded  yellow  cryftals  by  coolfng,  among  which  was  carbonate  of  potafli  not 
■decompofed.  ... 

Thefe  cryftals  were  diflblved  in  water,  and  the  folution,  together  with  the  mother  water,  ' 
was  mixed  with  the  weak  nitric  acid  till  the  carbonate  of  potafli  was  faturated.  The  fluid 
Jiad  then  a  very  deep  orange-red  colour.  "When  mixed  with  a  folution  of  muriate  of  tiiji 
recently  prepared,  it  firft  afliimed  a  brown  colour,  which  afterwards  became  greenifli. 
When  mixed  with  a  folution  of  the  nitrate  pf  lead, '  there  was  an  immediate  regeneratiott 
of  the  red  lead.  And,  laftly,  by  fpontaneous  evaporation,  it  afforded  cryftals  of  a  ruby  re^ 
colour,  mlxe^.  with  cryftals  of  nitrate  of  potafli. 

Ninety-eight  paris  of  this  mineral,  decompofed  as  h^s  been  here  related,  having  aflx)rded  ^ 
Sj'parts  of  fulpl)ate".pf'leW,  ic6  parts' 'Would  have  afforded  82,65,  which  are  equivalent  to 
^j7,i  of  metallic,  lead.  "  No.wi  ^{nit'ting, 'aS  Is  proved  by' experiment,  that  100  parts  of  lead 
:   ■V:oj-.il.-13EcM79$.'^''  "  •'  '••  '  •  "'■ -^E-    •'         -     ••    -•     ■  ■    -         ■    ablbrb^ 


!<)•  Neiv  Metallic  Aeid  in  Sthei'lan  Rtd  Ltatt, 

abforb,  in  order  to  combine  with  acids,  li  parts  of  oxygen,  the  57,1  of  metallic  lead  muft: 
contain  in  the  red  lead  6,86  of  this  principle  5  which  leaves  the  weight  of  the  mineralifing 
acid  36,4. 

Experiment  6.  —To  verify  by  fynthefis  the  prdportion  of  principles  found  by  analyfis  in. 
the  red  lead,  I  diflblved  50  grains,  ov  about  a>654  grammes,  of  metallic  lead  in  ni^r^c 
acid,  which  was  divided  into  two  equal  parts-  One  of  thefe  was  completely  precipitated. 
by  the  requifite  quantity  of  the  combination  of  the  acid  of  red  lead  with  potafh  ;  and  I 
obtained  43  grains,  or  about  2,285  grammes,  of  red  lead  as  fine  as  the  native  mineral 

The  other  portion  of  the  nitrate  of  lead,  precipitated  by  cauftic  potafti,  afforded  28  grains 
of  the  white  oxide  of  lead.  So  that  by  this  fynthefis  ido  parts  of  red  lead  would  be  com- 
pofed  of  65,12  of  oxide  of  lead,  and  34,88  of  acid.  It  gives,  therefore,  a  difference  pf 
1,72  lefs  of  acid  than  waft  deduced  by  the  analyfis,  jn  the  mineraliling  acid  of  the  red  lead  ^ 
a  difference  which  (hews  as  great  a  degree  of  accuracy  as  the  chemical  methods  can  afford^ 

SECTION    IV. 

Tie  fecmd  Procefs  for  decompoftng  the  Red  Lead  Ore. 

ANOTHER  method,  of  which  the  execution  is  no  lefs  eafy  than  the  foregoing,  confiffs 
in  pouring  100  parts  of  muriatic  acid  diluted  with  the  fame  quantity  of  water  upon  leO' 
parts  of  the  red  lead  ore  in  powder,  and  occafionally  agitating  the  mixtU/re. 

In  this  cafe  the  muriatic  acid  combines  with  the  oxide  of  lead,  and  forms  an  infoluble  fait,, 
which  falls  down,  while  the  acid  of  the  red  lead  remains  diffolved  in  the  water  which  was 
before  mixed  with  the  muriatic  acid.  The  fluid  affumes  a  colour  perfedlly  refembling  that 
of  the  red  lead  before  it  was  pulverifed.  As  foon  as  it  is  perceived  that  the  muriatic  acid 
exerts  no' further  action  on  the  red  lead,  and  the  precipitated  muriate  of  lead  ftill  contain?, 
fome  red  particles,  the  fupernatant  liquor  is  decanted,  and  a  new  quantity  of  muriatic  acid, 
<Dne  third  or  one  fourth  of  the  original  quantity,  and  diluted  in  the  fame  manner,  is  poured 
on  the  refidue. 

The  decompofition  being  complete,  the  fecond  folutlon  is  decanted,  and  added  to  the 
firft  ;  the  refidue,  is  walhed  with  a  fmall  quantity  of  cold  water,  which  is  alfo  added  to  the- 
folutions  before  decanted  off. 

In  this  procefs  the  operator  finds  himfelf  under  the  necedlty  of  obtaining  his  acid  of  red 
lead  mixed  with  a  certain  quantity  of  muriatic  acid,  or  of  leaving  a  portion  of  the  red  lead 
jmdecompofed. 

In  faft,  if,  according  to  the  known  proportions  of  the  component  parts,  no  more  of  thfc 
muriatic  acid  were  to  be  added  than  is  neceffary  for  the  faturation  of  the  oxide,  part  of  th& 
red  lead  would  efcape  decompofition  ;  for  it  appears  that  the  acid  of  the  red  lead,  at  the- 
time  of  its  feparation,  unites  witli  a  portion  of  the  muriatic  acid,  which  feems  neceffary 
for  its  more  ready  folution  in  the  water. 

Of  thefe  two  inevitable  inconveniences  I  have  therefore  preferred  that  which  leaves  % 
faiall  portion  of  the  muriatic  acid  in  the  acid  of  red  lead,  becaufe  it  is  eafy  to  feparate  it. 

For  this  purpofe  the  acid  of  the  red  lead,  contaminated  with  muriatic  acid,  is  to  be  di- 
luted with  a  fmall  quantity  of  water,  and  left  at  reft  in  a  cool  place  for  feveral  days,  in 
order  that  the  fmall  portion  of  muriate  of  lead  which  it  may  contain  fhould  cryftallize  and 

fall  down.    The  fluid  is  then  to  be  filtered  or  drawn  off  by  a  fyphon ;  and  to  this  muft  be. 

added. 


tJ'aturt  imi  Fropirties  of  the  Acid  of  Siherhn  Rid  Leai^  J^ 

»ided^  a  little  at  a  time,  the  oxide  of  Civer  precipitated  from  its  folution  by  lime  water  of 
ty  a  cauftic  alkali,  and  well  waflied. 

The  oxide  of  filver  unites  by  preference  with  the  muriatic  acid,  and  forms  with  it  a  white 
infoluble  fait,  which  falls  to  the  bottom  of  the  fluid.  But  great  care  muft  be  taken  not  to 
«dd  too  great  a  quantity  of  the  oxide  of  filver,  becaufe  it  will  unite  likewife  with  the  acid  of 
the  red  lead,  and  form  an  infoluble  combination,  which  will  mix  with  the  muriate  of  filver. 
As  foon,  therefore,  as  it  is  obferved  that  the  oxide  of  filver  aflumes  a  purple  red  colour,  it 
is  a  fign  that  the  muriatic  acid  is  entirely  faturated,  and  no  more  of  the  oxide  muft  be 
added.  It  is  better,  however,  to  add  too  much  than  too  little  ;  for,  in  this  cafe,  the  only 
danger  Is  that  of  lofing  a  fmall  quantity  of  the  acid  of  red  lead  ;  whereas,  in  the  other,  the 
inconvenience  will  be,  that  a  portion  of  the  muriatic  acid  will  be  left  in  combination  with 
■flie  metallic  acid.  When  the  acid  of  red  lead,  mixed  with  muriatic  acid,  is  evaporated 
fa)  drynefs,  a  lilac-coloured  powder  is  obtained,  which  becomes  green  by  the  conta£l  of  the 
inr,  and  is  a  combination  of  the  oxide  of  the  new  metal  with  the  muriatic  acid. 

SECTION  V. 

^le  Nature  and  Properties  of  the  Acid  of  Red  Lead. 

THE  acid  of  red  lead,  prepared  according  to  the  foregoing  inftru£lions,  is  of  an  orange- 
Tcd  colour,  with  a  (harp  metallic  tafte.  It  is  very  foluble  in  water,  and  its  folution  evapo- 
rated by  a  gentle  heat,  or  fpontaneoufly  by  expofure  to  the  air,  cryftallizes  in  fmall  long 
prifms  of  a  ruby-red  colour. 

Experiment  i . — Paper  wetted  with  this  acid,  and  expofed  for  feveral  days  to  the  fun's 
light,  aflumes  a  green  colour,  which  does  not  change  in  obfcurity. 

Experiment  2. — A  plate  of  iron,  of  tin,  or  moft  of  the  other  metals,  Immerfed  in  the  folu- 
6.on.  of  this  acid,  caufes  it  to  aflume  the  fame  colour. 

Experiment  3. — Ether  or  alcohol,  boiled  for  a  few  inftants  with  this  fubftance,  produces 
the  fame  effeft. 

Experiment  4.— The  muriatic  acid,  heated  in  a  retort  with  this  acid,  whether  foHd  or  in 
folution,  produces  a  lively  effervefcence.  Much  oxygenated  muriatic  acid  is  afforded,  and 
the  fluid  aflumes  a  beautiful  deep  green  colour. 

Experiment  5.— Thefe  phenomena,  which  alfo  take  place  when  the  ore  of  red  lead  is 
idlflblved  in  the  muriatic  acid  by  means  of  heat,  having  led  me  to  prefume  that  the  acid  of 
fed  lead,  by  virtue  of  the  great  quantity  of  oxygen  it  contains,  and  the  flight  adherence  it 
contracts  with  that  principle,  might  favour  the  folution  of  gold  in  the  muriatic  acid,  I  put 
fome  leaves  of  that  metal  in  a  mixture  of  thefe  two  acids,  and,  by  a  flight  ebullition,  I  ac- 
tually obtained  a  complete  folution  of  the  gold. 

The  colour  of  this  folution  was  green  ;  it  tinged  the  flcin  purple ;  and  the  folution  of  titt 
recently  prepared  occafioned  a  very  abundant  precipitate  of  the  fame  colour. 

Experiment  6,— This  acid,  mixed  with  a  folution  of  the  hydro-fulphuret  of  pot-aih.  Is  pre- 
cipitated in  greenilh  brown  flocks. 

Experiment  7. — The  aqueous  fplwtjon  of  the  tanning  principle  precipitates  it  in  flocks  o« 
3  yeUowifli  brown  colour, 

2  E  a  pKperiment 


jlpt  ■  Ntw  Metallic  All  o/.'Sihrlak  Red  'Lead. 

Experiment  8.— Heated  by  the  blow-pipe  upon  charcoal,  it  boils,  and  leaves^a  green, iSf. 
fufible  fubftance. 

Experiment  9. — When  fufed  with  the  phofphoric  glafs,  or  with  borax,.. it  communicatea^ 
to  the  vitreous  globules  a  very  fine  emerald  green  colour.  ■  !  ' 

Experiment  10. — Laftly,  this  acid  combines  with  alkalis  and  earths,  from  which  it  dif* 
engages  the  carbonic  acid  with  eflervefpence,  :and  forms,  with  thofe  fubftances,  falts  more 
or  lefs  coloured,  of  which  the  properties  a^re  defcribed  in  the  following  feftion. 

From  the  preceding  refults  it  evidently  follows,  that  thp  min,eraHfer  of  the  red  lead  ore  is 
a  true  acid  j  that  the  radical  of  this  acid  is  a. peculiar  metallic  fubftance ;  for  no  other  metallic 
acid  yet  known  exhibits  properties  fimilar  to  the  prefent.  In  fait.  What  metallic  atid  pof-. 
feffes  a  ruby  colour;  com'municates  to  all  its  combinations  red  or  yellow  colours,  more  or; 
lefs  deep,  or  yields  to  the  muriatic  acid  part  of  its  oxygen,  converting  it  into  the  oxygenated 
muriatic  acid,  while  itfelfpaffes  to  the  ftate  of  a  green  oxide,  foluble  in  the  muriatic  acidJr 
Laftly,  What  metallic  acid  is  there,  which  forms  with  merciiry. a. combination  of  a  cinna- 
bar red  ;  with  filver,  a  carmine  red  compound  ;  with  lead,  an  orange-yellow  mineral ;  with 
the  hydro-fulphuret  of  potafli,  an  olive-green,' &c.^- If  I  am  not  deceived,  there  is  none 
fuch.  Therefore,  notwithftanding  the  repugnance  which  I  have  to  admit  new  fimple 
bodies,  a  repugnance  grounded  on  the  numberlefs  modifications  which  nature- may  give 
to  bodies  already  known,  and  render  them  apparently  new,  I  am  neverthelefs  forced,  by. 
the  great  number  of  new  characters  pofTeffed  by  this  and  by  rio  other  fubftance,  to  regard, 
it  as  a  metal  naturally  acidifiied,  which  refembles  no  other  we  are  acquainted  with. 

This  opinion  will  be  ftill  more  confirmed  by  thq  experiments  in  the  following  para- 
graphs. 

SECTION    VI.        • 

Combimtiofii  of  the  Acid  of  Red  Lead  ivith  Alkalis,  Earthsy  and  Metallic  Oxides.  : 

THE  fmall  quantity  of  native  red  lead  which  I  have  hitherto  poffefled,  has  not  allowed 
me  to  prepare  any  large  maffes  of  the  falts  which  this  acid  is  capable  of  forming  with  the 
Alkaline,  earthy,  and  metallic  fubftances;  in  ordet  to-.ex^rriine  their  properties  with  all  the 
precifion  neceflary  to  render  them  perfectly  known.  I  (hall  confi-ne  myfelf,  therefore,  in 
this  place,  to  exhibit  their  principal  chara£ters,  fuch  as  colour,  folubility  in  water,  tafte, 
their  habitudes  in  the' fire,  ■&c.  referving  rnyfelf  to  return  to  this' object  when  circum- 
ftances  fliall  be  more  favourable.  It  is  well  known*  like  wife,  that  a  great  interval  of  time  fre- 
quently takes  place  between  the  period  when  the  difcovery  of  an  uncommon  fubftance  ha& 
been  made,  and  that  in  which  all  its  properties  are  perfedtly  known,  and  that  refearches 
of  this  kind  are  ufually  indebted  to  time  and  opportunity  for  their  ultimate  degree  of 
perfection.  ; 

,  Qomhination  of  the  Acid  of  Red  Lead -with  Barytes.. 

The  acid  of  red  lead  ore  readily  unites  with  barytes,  with  which  it  fdrms  a  fait  of  very 
faring  folubility ;  for,  by  pouring  an  aqueous-foluiion  of  this  acid  into  a  folution  of  the 
earth,  a  precipitate  is  formed  of  a  pale  lemon-yellow  colour.  This  fait,  however,  is  not 
entirely  inioluble  ;  for  the  fupernatant  fluid  ftill  retains  a  flight  yellow  colour,  though  the 
two  principles  of  the  fait  are  mutually  faturated.     This  pulverulent  fait  has  no  perceptible' 

tafte; 


)dcid' of  Rid  Lead  Orec-ifivj  Earth  cf  Berjh.  393; 

tsffe ;  it  is  decompofed  by  the  mineral  acids  i  it  gives  out  oxygen  gas  by  heat,  and  thcrC'* 
fiiiue  is  an  earthy  mafs  of  a  green  colour. . 

Comhination  of  the  Acid  of  Red  Lead  -with  Lime. 

LiM  E  combines  with  the  acid  of  red  lead,  and  affords  a  fait  which  does  not  appear  to .-. 
be  more  foluble  than  the  foregoing  :  for,  by  mixing  lime-water  with  a  folution  of  this  add,.,. 
a»depofition  of  an  orange-yellow  colour  is  made,  which.is  lefs  abundant  than,  with  barytes  J  . 
a.conlequence  which  naturally  follows,  from,  the  barytes  bdng  about  twenty  times  more 
foluble  in  cold  water  than  lime ;  in  confequence  of  which  the  precipitate  formed  with  this  . 
lad  earth  muft  be  twenty  times  lefs  in  quantity.     A  large  quantity  of  fait,  of  the  fame  co- 
l^wr  as  the. former,  is  alfo  obtained  by  evaporation  of  the  fluid.     The  fait  farmed  by  the. 
combination  of  lime  and  the  acid  of  red  lead  does  not  appear  to   differ  from  that  of  barytes, 
except  in  its  being  lefs  foluble,  and  poffclling  different  alEnities  and  proportions  of  compa-  - 
nent  parts. 

Its  habitudes  with  acids,  and  with  heat,  are  the  fame  asthofe  of  the.  combination  of  ba-< 
rytes  with  the  fame.  acid. . 

(To  be  concluded  in  our  next.) 


.  ni. 

Information  refpeBing  the  Earth  of  the  Beryl .-  in  Continuation  of  the  firji  Memoir  on  the  fame  • 

Subject.     By  Citizen  Vau^ELIN*, 

A  HAVE  announced  in  my  Memoir  on  the  Earth  oFthc  Beryl,  that  this  foflil  contains--, 
about  8  per  cent,  of  that  principle  ;  but  at  the  fame  time  I  obferved,  that  I  did  not  confider  • 
this  proportion  as  being  very  accurate,  becaufe  I  prefumed  that  a  certain  quantity  had  been, 
diflblved  by  the  potalh  employed  to  feparate  the  alumine.  .  ' 

I  alfo  announced  that  I  had  begun  fome  trials,  to  afcertain  whether  the  alumine  contained  1 
in  the  beryl  was  in  fa£l  contaminated  by  a  mixture  of  this  new  earth..    The  refult  of  thefe 
experiments,  related  in  a  few  words,  will  form. the  fubje£l  of  the  prefent  communication; 
to  the  Inftitute,  together  with  an  account  of  certain  properties  of  this  fubllance,  of  which  I  > 
have  fince  extrafted  a  larger  quantity.  ,  , 

Experiment  I.  I  put  together  the  alumine  which  had  been obtaitied from  three  dtjcimaftic? 
quintals  of  beryl,  which  had  beenanalyfcd  in  the  fame  number  of  feparate  operations.  The, 
quantity  was  63  gramme?.  I  diffolved  them  in  fulphuric  acid,  and,  after  having  (brevetel. 
the  folution,  I  fubmitted  it  to  evaporation  to  obtain  the  alum.  The  evaporation,  was., 
continued  until  cryft^ls  were  UQ  longer  affordedj  The  remaining  mother  water,  was  .very  ■• 
faccharine. and  thick.  .  ,      " 

Experiment  2.  I  mixed  this  mother  water  with  a  folution  of  carbonate  of  ammoniac  mor£.- 
tVn  fufficient  to  faturate  the  acid.    The  mixture  was  repeatedly  (halcen  during  twenty-four 
hours.   I  perceived  that  the  bulk  of  the  precipitate  thrown  down  by  the  firft  po.rtions  pf  the  ■ 

•  Tlie  firft  Memoir  is  inferted  in  the  prefent  volume  of  our  Journal,  page  35.8,.,  TJ{U  .coptifluatjon  is  tranf-> 
latjd  fi^Q"* '^'^s  Annales  de  Chiwie,  xxvi.  1 70,  ,„      >;  * 

^'1  ■  -      ■       •  -^ua  t  *>«fi  *•■•    .,     ■-'•J 

1!    •  carbonate' 


jl^^'  ^mt'ity  ef  the  tnvo  Sarlfs  cwtaimi  h  the  Btrjf. 

iiartronate  liad  Tcry  perceptibly  decreased.  At  the  expiration  of  thai  time  I  filtered  ths 
fluid,  to  feparate  the  undiffolved  part :  this  laft,  after  wafliing  and  ignition,  weighed 
5  grammes,  and  had  all  the  properties  of  alumine. 

Expeyime/it  3. — I  expofed  the  ammoniacal  folution  to  the  aflion  of  heat  in  a  capfule  of 
porcelain  :  as  foon  as  the  temperature  was  fufficiently  elevated  to  drive  off  the  carbonate  of 
ammoniac,  a  large  quantity  of  a  white,  granulated,  and  very  voluminous  earth  was  depo- 
Cted.  I  continued  the  evaporation  until  all  the  ammoniacal  fait  was  diffipated.  I  then 
threw  the  refidue  upon  a  filter,  and  waflied  it  with  much  water.  This  refidue,  after  drying 
by  a  gentle  heat,  was  perfe£lly  white,  pulverulent,  and  foluble  in  acids,  with  a  ftrong  effer- 
vefcence.  It  weighed  4.2  grammes,  which  by  a  red  heat  were  reduced  to  25  grammes  ( 
whence  it  follows,  that  thcfe  42  grammes  contained  17  grammes  of  carbonic  acid  and 
writer. 

Confequently,  the  three  quintals  of  beryl  having  afforded  24  grammes  of  the  new  earth 

which  was  not  difTolved  by  potafli,  and  the  alumine  which  thefc   three  quintals  afforded 

having  alfo,  as  has  been  juft  obferved,  25  grammes  of  the  fame  fubftance,  it  is  evident  that 

each  quintal  of  beryl  contains  16,33.     One  hundred  parts  of  beryl  are  therefore  cotni 

pofed  of 

69  parts  filex, 

16  earth  of  beryl, 

13  alumine, 

I  oxide  of  iron, 

0,5  lime, 

99.5 

Experiment  4. — I  have  obferved  in  my  firft  Memoir,  that  alumine  diflblved  m  the  nitria 
acid  was  precipitated  by  the  earth  of  beryl.  I  was  defirous  of  knowing  whether  the  fame 
phenomenon  would  likewife  take  place  with  alum.  I  therefore  diflblved  one  hundred  parts 
of  this  fait  in  about  fix  hundred  parts  of  hot  water.  The  folution  afforded  cryftals  of  alum. 
Into  this  folution  I  put  a  certain  quantity  of  the  earth  of  beryl,  recently  precipitated  from  a; 
falotion  by  ammoniac,  and  well  wafhed.  The  mixture  was  boiled  for  an  hour.  I  foon  per-, 
ceived  that  the  earth  of  beryl  was  taken  up ;  and  in  proportion  as  the  excefs  of  acid  in  tlie 
alum  was  faturated,  there  fell  down  a  great  quantity  of  earthy  matter,  in  white  flocks,  in 
a  very  divided  flate.  As  foon  as  the  decompofition  appeared  to  me  to  be  complete,  I  fil- 
tered the  liquor,  and  coUedbed  the  precipitated  earth,  which,  when  wafhed  and  difTolved 
in  the  fulphuric  acid,  afforded,  with  a  fufficient  quantity  of  fulphate  of  pot-afh,  cryftals  of 
alum  perfedly  oftahedral. 

The  fluid  from  which  the  alumine  had  been  feparated  pofTefTed  a  very  faccljarine  taflc ; 
and,  when  fubjeded  to  evaporation,  it  did  not  afford  alum.  Hence  we  find,  that  the  earth 
of  beryl  has  a  greater  afBnity  than  alumine  with  refpefk  to  the  fulphuric  acid,  as  well  as 
the  nitric. 

Experiment  5.— Being  defirous  of  afcertaining  ftill  more  efFe^ually  the  difference  which 
exifts  between  alumine  and  the  earth  of  beryl,  I  diflblved  ten  parts  of  the  former  earth  m 
the  fulphuric  acid ;  and  after  having  add€d  the  neceffary  quantity  of  fulphate  of  pot- 

afh, 


Properihs  of  the  new  Sarih  9/  Ser^K  f^f^ 

«ffi,  T  ottameJ,  by'  fevcral  fucceflivc  cryftallizations,  90  parts  of  alum.  I  alfo  diflblved 
10  parts  of  the  earth  of  beryl  in  the  fame  acid,  and  added  the  fame  quantity  of  fulphate  of 
pot-afti.  I  obtained  only  50  parts  of  fait  in  fmall  cryftalline  grains,  of  which  I  could  not 
determine  the  figure.  This  fait  is  foluble  in  7  or  8  parts  of  cold  water,  a  quantity  very 
kifufficient  to  diflblve  alum  at  the  fame  temperature. 

There  cannot,  therefore,  remain  any  doubt  concerning  the  particular  nainre  of  the  earth 
contained  in  the  beryl ;  which  muft  henceforward  be  reckoned  in  the  namber  of  fubftanccs 
of  this  order,  of  which  it  will  compofe  the  eighth  fpecies. 

It  almofl  always  happens  in  the  fciences  of  obfervation,  and  even  in  the  fpcculatlve  fcl-" 
ences,  that  a  body,  a  principle,  or  a  property,  formerly  unknown,  though  it  may  often  hare 
been  uted,  or  even  held  in  the  handsj  and  referred  to  other  fimplc  fpecies,  may,  when  once 
difcovered,  be  afterwards  found  ia  a  great  variety  of  fituations,  and  be  applied  to  many  ufc- 
ful  purpofes. 

Chemiftry  affords  many  recent  examples  of  this  truth.  Klaproth  had  no  fooner  dlfcovered 
the  different  fubftances  with  which  he  has  enriched  the  fcience,  but  they  were  found  ii» 
Tarlous  other  bodies  ;  and  if  I  may  refer  to  my  own  procefTes,  it  will  be  fecn,  that  after  I 
had  determined  the  charafters  of  chrome,  firft  found  in  the  native  red  lead,,  I  eafily  recog- 
nifed  it  in  the  emerald  and  the  ruby.  The  fame  has  happened  with  regard  to  the  earth  of 
the  beryl.  I  have  likewife  detefted  it  in  the  emerald  ;  in  which,  neverthelefs,  it  was  over- 
looked both  by  Klaproth  and  myfelf  in  our  firft  analyfis  i  fo  diiEcult  it  is  to  be  aware  of  the 
prefenee  of  a  new  fubftance,  particularly  when  it  pofleffes  fomc  properties  refemWing  thofe 
already  known  ! 

Though  I  have  not  yet  determined  with  ntuch  accuracy  the  proportion  in  vrfiich  this- 

earth  exifts  in  the  emerald,  I  think,  neverthelefs,  that  it  is  nearly  the  fame  as  in  the  beryl  ;. 

but  I  fhall  afcertain  this  point  witli  more  certainty  in  my  fecoiid  analyfis.     The  emerald 

and  the  beryl  are  therefore  two  ftones  of  the  fame  nature,  excepting  the  colouring  part  j, 

and  the  fciences  of  cryflallography  and  chemiflry  are  here  alfo  perfectly  confiftent  in  their 

jrefults, 

jf  Table  of  the  general  Fropertks  of  the  Earth  of  the  Beryl, 

I .  It  is  white. 

,    2.  Infipid. 

3.  Infoluble  in  water.  , 

4.  Adhefive  to  the  tongue. 

5.  Infufible. 

6.  Soluble  in  the  fixed  alkaKs. 

7.  Infoluble  in  ammoniac. 

8.  Soluble  in  the  carbonate  of  ammoniac* 

9.  Soluble  in  almofl  every  one  of  the  acids  (except  the  carbonic  and  phofphorjie  acidrs)j 

and  forming  falts  of  a  faccharine  tafte. 
JO.  Fufible  with  borax  into  a  tranfparent  glafs. 
J  I.  Abforbs  one-fourth  of  its  weight  of  carbonic  acid. 

12.  Decompofes  the  aluminous  falts. 

13,  Is  not  precipitable  by  well-faturated  hydro-fulphurets> 

J  Talh 


-,3^  ,'      6«  Ehnticity,  Lfgfjt,  ani  Calorkt 

A'table  of  the  j^ecific'CharaSlert  of  the  Earth  of  Bivjl, 
•5,  Its  falts  arc  faccharine,  and  (lightly  aftringent. 
a.  It  is  very  foluble  in  the  fulphurlc  acid  by  excefs. 
^     .3,  It  decompofes  the  aluminous  falts. 

4.  It  is  foluble  in  the  carbonate  of  ammoniac. 
:5^  Is  completely  precipitated  from  its  folutions  by  ammoniac. 
^.  Its  affinity  for  the  acids  is  intermediate  between  magnefia  and  alumine. 
None  of  the  known  earths  unite  the  fix  properties  announced  in  this  table, 
I  prefent  to  tlie Tnftitute  a  certain  quantity  of  this  earth,  and  fliall  produce  at  one  of  its 
•  future  fittings  a  feries  of  combinations  formed  with  this  earth,  extra£ted  from  a  confiderable 
:  quantity  of  beryl  given  to  me  by  Citizen  Patrin,  whofe  zeal  for  the  advancement  of  tlic 
Sciences  is  well  known  to  every  one  of  their  cultivators.   ' 


IV. 


Ohfervations  on  EleHricity,  Light,  and  Caloric,  chief  y  direSfed  to  the  Refults  of  Dr.  TEARSOift 
Experiments  on  EleBric  Dijcharges  through  Water.     By  a  Correfpondent, 


^m. 


To  Mr.  N  I  C  H  O  L  S  O  N. 

SIR, 


HEN  I -received  the  6th,  7th,  and  8th  Numbers  of  your  Journal  for  1797,  in 
fucceffion,  I  read  Dr.  Pcarfon's  Experiments  and  Obfervatioas  on  the  Gaz  produced  by 
•yaffing  Eleftric  Difcharges  through  Water  *,  with  attention. 

His  experiments  appeared  to  me  to  be  well  devifed  and  conduced,  and  his  conclufionj 
fair  and  fatisfa£tory  :  but  his  explanations  of  the  manner  in  which  thofe  gazes  were  pro- 
duced from  water,  and  then  re-converted  into  water  by  the  fame  agent,  the  eleftric  fluid, 
«rere  l)y  no  means  fatisfa£l:ory. 

That  I  might  not  be  premature  in  my  decifions  againft  Dr.  Pearfon's  principles  or 
reafonings,  I  diverted  my  attention  from  the  fubjeft  till  now;  but,  upon  the  re-perufal  of 
liis  papers,  I  ilill  think  his  principles  lax  and  indeterminate,  and  his  reafonings,  in  part, 
«nphilofophical,  and  to  me  apparently  indefenfible.  I  take  the  liberty,  therefore,  of  laying 
the  few  following  animadverfions  and  objedlions  before  you  : 

The  cleftric  fluid,  common  fire,  and  light,  thofe  univerfal  and  general  agents  of  nature, 
io  far  from  being  underftood,  appear  to  me  to  be  not  only  confounded,  but  alfo  to  be  fo 
imperfeftly  confidered,  as  to  be  the  caufe  of  endlefs  confufion  in  every  department  of 
philofophy. 

Oxygen  gaz  is  faid  to  \>z  formed  of  oxygen  and  caloric  : — what  idea  then  are  we  to  form 
of  caloric  ?— Is  ii  a  fimple,  homogeneous  principle,  or  is  it  a  compound  ? — The  general 
idea,  or  at  lead  the  common  expreffioh,  feems  to  imply  the  idea  of  its  being  fimply  the 
calorific  principle,  and  confequently  uncompounded. 

Oxygen  may  be  converted  into  oxygen  gaz  by  the  eleftric  fluid,  or  by  light,  as  well  as 
Jjy  fire.    The  cledric  fluid,  then,  imparts  caloric  to  oxygen,  and  fo  does  light. — What 

•  Philof.  Journal  \.  J4i.  299.  349, 

ideas 


VThethei'  ElfcJridfy,  Light  and  Cahrlc  Itftniph,  emptuttdeJ,  ^e,  397 

ideas  tlien  are  we  to  form  cf  the  cleftric  fluid  and  of  light  ? — Are  they  merely  modifica- 
tions of  fimple  caloric,  or  are  they  compounds  in  which  caloric  forms  a  part  ? 

If  the  eieftric  fluid  be  a  mode  of  exiftence  of  fimple,  homogeneous  caloric,  how  are  we 
to  explain  the  faft  *,  that  certain  ele£lric  atmofpheres  repel  each  other,  which  atmofpheres 
will  attra£t  other  ele£lric  atfnofpheres  that  are  alfo  repulfive  to  each  other  ? 

It  is  incontrovertibly  evident  that  cle£tric  atmofpheres  are  of  two  diftinfl  kinds ;  equally 
cxtenfive,  equally  powerful,  and  mutually  attraftive  to  each  other;  although  each  is 
invariably  repulfive  to  every  atmofpherc  of  the  fame  kind  as  itfelf ;  and  it  is  equally  certain 
<hat  they  only  produce  fire,  or  take  that  form  when  they  rufli  together,  and  ceafe  to  be 
eleftric  Inftead,  then,  of  fuppofin^,'  the  ele6lric  fluid  to  be  caloric,  or  partly  formed  of 
caloric,  it  appears  to  me  to  be  more  philofophical  to  fuppofe  that  it  confiflis  of  two  prin- 
ciples t  in  flates  of  feparation,  which  form  caloric  when  they  quit  their  eleflric  dates,  and 
combine. 

Is  light  a  fimple  fluid  %,  or  a  modification  of  caloric  ? — If  fo,  what  ingenuity  can  explain 
how  one  homogeneous  fluid,  or  fimple  fire,  can,  by  paffing  through  a  prifm,  be  feparated 
into  fuch  variety  of  parts  fo  permanently  diflimilar  to  each  other  ?  and  how  happens  it  that 
light  never  produces  fire  but  by  evidently  changing  its  mode  of  exiftence,  as  it  ceafes  to  be 
light  when  it  takes  the  ftate  and  properties  of  fire  ? — This  confideration  again  feems  to  lead 
to  the  conclufion  that  light  confifts  of  diftinfi:  and  diflimilar  principles,  which,  combining 
together,  iofe  their  properties  as  light,  and  conftitute  a  fluid  of  very  different  properties 
and  charafter,  which  we  call  fire,  or  caloric. 

Nay,  even  if  we  advert  to  caloric  itfelf,  is  It  an  uncompounded  principle,  or  can  any 
fimple  principle  polfibly  perform  the  various  parts  afllgned  to  it  ? — According  to  the  pre- 
fent  fyftem  of  chemiftry,  caloric,  homogeneous,  fimple  caloric,  deftroys  combinations 
which  itfelf  had  formed ;  it  attaches  itfelf  to  particles  of  matter,  and  forms  itfelf  into 
repulfive  fpheres  around  them  :  and  yet  certain  fpheres  of  caloric  in  this  ftate  of  repulfion 
will  rapidly  attracD:  other  fpheres  of  the  fame  caloric  in  fimilar  ftates  of  repulfion  1  In 
fiiort,  caloric  is  hot  or  cold,  attradtive  or  repulfive,  vifible  or  invifible,  juft  as  occafion 
may  ferve ;  and,  Proteus-like,  it  takes  all  Ihapes  and  forms : — we  dread  to  meet  it  in  Jove's 
thunderbolt,  and  court  its  influence  in  the  cooling  breeze  1 

«  The  fafts  are  fira^ily,  that  AxAVj  attraft  and  repel  each  other  in  certain  ftates  of  eleftrization;  but  the 
exiftence  of  eleftric  atmofpheres,  of  one  fimple  eleflric  fluid,  or  of  two,  &c.  are  mere  hypothcfcs  which  yet 
remain  without  proof.  M.  de  Luc  (Idees  fur  la  Meteorologie)  fuppofes  cleftricity  to  confiftof  the  matter  of 
heat  combined  with  another  matter  incapable  of  paffing  through  glafs,  &c.  and  that  the  charge  is  produced  by 
the  condenfation  of  this  laft  with  the  tranfmiilion  of  heat,  in  the  fame  manner  as  fteam  (water  and  heat) 
might  be  condcnfed  on  a  pane  of  glafs,  and  caufe  the  evaporation  of  water,  fuppofed  to  be  placed  on  die  oppo- 
fite  furface,  by  virtue  of  the  tranfmitted  heat.   N. 

tj-  That  light  of  every  kind  is  emitted  by  the  eleftric  fpark  is  eafily  feen  with  the  prifm,     N. 

X  The  great  Leonard  Euler,  and  others,  have  maintained  that  the  fenfations  and  effefts  of  light  are  merely 
confcquences  of  the  vibrations  of  a  rare  and  very  elaftic  fluid.  To  this  doftrine  have  been  oppofed  the  rcfti- 
llnear  motion  oflight,  which  does  not  flow  into  the  lateral  fpaces,  together  with  its  refleftion,  refraftion,  and 
cslours.  Much  complexity  of  vibration  would  indeed  be  required  to  account  for  thefe  phenomena :  but  not 
more,  perhaps,  than  neceflarily  refults  from  the  confideration  of  found ;  its  echo,  which  deviates  little  fron\ 
the  angle  of  refleftion ;  and  the  harmony,  melody,  tone,  &c.  of  its  diftinft  cotcmporaneous  and  fuccefiive 
impreffions.     N. 

Vol.  II.— Dec.  1798.  3  F  Haying 


398  -On  the  Ef eel  of  EkElncH^  upon  Water ^   isfc. 

Having  thus,  In  a  seneral  way,  pointed  out  the  confufion  which  obfcures  and  depre- 
ciates philofophy  in  confequence  of  employing  words  without  ideas,  and  of  admitting 
certain  agents  as  fimple  principles  which  probably  are  compounds,  without  deigning  to 
(C onGder  whether  they  are  fo  or  not,  even  though  the  moft  palpable  a.bfurdities  attend  the 
admiflion ;  permit  me  to  make  a  few  critical  remarks  updii  th?;|>ap«f  iaqueftion. 

Dr.  Pearfon  explains  the  produ61ion  of  the  gazes  frpjto  jwffter,  by  fuppofing  that  the 
denfe  electric  fire,  at  the  moment  of  diftufion,  interpofes  betwixt  the  conftituent  clement^ 
•f  water,  and  places  them  beyond  the  fphere  of  attraclsion  for  each  other,  when  each 
ultimate  particle  of  the  oxygen  and  hydrogen  unites  with  a  determinate  quantity  of  fire, 
and  they  form  hydrogen  gaz  and  oxygen  gaz. 

It  appears,  tlien,  that  ele£tric  fire  forcibly  deftroys  the  chemical  union  between  oxygen 
and  hydrogen  ;  and  that  then  a  portion  of  it  aflumes  the  ftate  of  caloric,  attaches  itlelf  to» 
the  particles  of  oxygen  and  hydrogen,  and  counteracts  their  chemical  union,  by  keeping 
them  diftant  from  each  other  in  the  ftate  of  gaz. 

Dr.  Pearfon  then  proceeds  to  explain  In  what  manner  thefe  two  gazes  arc  made  to  re- 
eombine,  and  form  water,  by  means  of  the  ele<Slric  fire  or  caloric.  He  firfl.  points  out  the 
manner  in  v/hieh  he  fuppofes  the  caloric  ails  in  thefe  words  : — "  I  conceive  its  agency  to 
be  merely  dimlniihlug  or  deflroying  the  powers  which  counteraft  chemical  union  j"  and 
then  proceeds  to  apply  his  theory  to  the  explanation  of  the  produftion  of  water  from 
hydrogen  gaz,  and  oxygen  gaz,  by  the  agency  of  caloric,  in  thefe  words  : — "  Accordingly, 
when  an  ele£l:ric  fpark,  or  the  fmalleft  particle  of  flame,  or  of  an  ignited  fubftance,  is 
applied  to  the  gaz  produced  in  the  above  procefs,  or  to  the  mixture  of  hydrogen  and 
oxygen  gaz,  the  ultimate  particles  of  thefe  gazes  neareft  to  the  flame  are  driven  from  it  in 
all  dire<Slions,  as  from  a  centre,  by  the  iiiterpofition  of  fire,  or  of  caloric  and  light ;  fo 
(hat  they  are  brought  within  the  fphere  of  their  chemical  attraftion  for  the  ultimate  par- 
ticles of  the  gafes  at  a  certain  diflance  from  the  centre  of  application  of  fire,  which  there- 
fore unites,"  &c.  Now,  I  muft  take  the  liberty  to  fay,  that  I  think  this  no  explanation 
•whatever.  The  conclufion  appears  to  me  to  be  drawn  from  premifes  which  neither  war- 
rant fuch  conclufion,  nor  make  it  either  probable  or  conceivable. 

According  to  Dr.  Pearfon's  own  theory  and  explanation,  caloric  counterafts  the  chemi- 
cal union  betwixt  oxygen  and  hydrogen,  and  holds  them  in  the  ftate  of  gas  j  and,  accord- 
ing to  his  own  principles,  he  ought  to  have  explained  \\\  wh.it  manner  the  caloric  of  an  ig- 
nited body  diminilhes,  or  deftroys,  the  fpheres  of  caloric  which  countera£t  their  chemical 
anion  -,  inftead  of  which  he  only  tells  us,  that  caloric  drives  the  ultimate  particles  of  thofe 
gazes,  neareft  to  it,  in  all  directions,  which,  therefore,  combine  with  other  particles  at  a 
diftance  ;  but  gives  no  idea  wliatfoever  of  the  manner  in  which  that  flame,  or  that  caloric, 
flowing  ofi"from  an  ignited  boay,  diminifties  or  deftroys  the  caloric  which  is  already  attached 
to  the  particles  of  oxygen  and  hydrogen,  and  counterafts  their  chemical  affinity  or  union. 
Ih  ihort,  if  caloric  adtually  is  attached  to  the  difuiiited  particles  of  oxygen  and  hydrogen, 
and  prevents  their  chemical  union,  nothing  that  Dr.  Pearfon  has  faid  tends,  in  the  lead,  to 
ihow  how  the  acceftion  of  ftill  more  caloric  can  either  diminifli,  or  deftroy,  the  caloric 
already  attached  to  them,  In  fufficient  quantity  to  prevent  their  union. 

Much  might  be  faid  upon  a  fubje£t  like  this  ;  but,  as. I  wiftj  not  to  take  up  too  much  of 
|our  time,  I  fliall  not  proceed  fvtrther  with  my  remarks  at  prefent.    What  I  have  already 

advanced 


Whether  Heat  be  Matter  ei-  Motion, 


89f 


advanced  is,  I  think,  fufficlent  to  (hew  that  Dr.  Pearfon's  explanation  of  the  fubje£l  in 
queition  is  neither  philofophical  nor  admiflible  ;  and,  for  the  credit  of  the  dodtrine  which 
he  efpoufes,  fome  more  fatisfa£lory  explanation  fhould  be  given.  With.  refpe61:  to  Dr. 
Parr's  theory,  that  light  and  fire  repel  each  other,  when  difengaged  from  matter,  it  appears 
to  me  too  fanciful  to  be  folid,  and  too  inconfiftent  to  be  fupported.  If  light  and  fire  repel 
each  other  when  difengaged  from  matter,  by  its  decompofition,  it  is  not  an  eafy  matter  to 
fhew  how  they,  when  in  ftates  of  freedom  and  confequent  repulfion,  were  brought  to- 
gether on  the  fame  fubftance  at  its  formation  :  and,  if  oxygen  and  light  repel  each  other, 
as  he  contends,  why  doee  light  combine  at  once  with  the  oxygen  of  nitric  acid,  and  form 
oxygen  gas,  by  merely  placing  the  acid  in  its  way  ?  But  this  is  not  the  hypothefis  I  have 
undertaken  to  combat.  , 

I  offer  this  letter  for  your  perufal,  and  confefs  that  I  wifli  to  fee  the  fubje£l:  impartially 
attended  to.  It  is  painful  and  humiliating  to  fee  how  readily  the  mod  glaring  abfurdhies 
are  overlooked,  nay,  even  adopted  as  principles,  and  employed  as  indifputable  fa£ts  ;  and 
po  further  proof  is  necefiary  to  point  out  the  confufion  and  abfurdity  to  vi'hich  fuch  erro- 
neous principles  tend,  than  the  refult  of  Count  Rumford's  experiments  and  reafonings  on 
the  produtSlion  of  heat  by  fri£llon  *;  which  is,  that  as  heat  thus  produced  by  friftlon  can- 
4iot  be  accounted  for  upon  the  adopted  principles  of  chemiftry,  he  feems  inclinable  to  con- 
■clude,  that  it  cannot  be  a  material  fubflance,  and  is  moft  probably  nothing  but  motion  !!! 
Surely  this  is  facrificing  too  much  to  hypothefis,  to  give  up  the  convlftion  of  reafon,  and 
the  teftimony  of  the  fenfes,  rather  than  fuppofe  it  pofiible  that  a  favourite  theory  may  be 
falfe.  The  produflion  of  heat  by  friftion,  is,  no  doubt,  inexplicable  upon  the  principles 
of  M.  Lavoifier,  which  ought  to  excite  the  fufpicion  of  thofe  who  have  embraced  them  ; 
for,  if  fo  fimple  a  fa£l  cannot  be  explained  by  thofe  principles,  it  is,  at  leaft,  probable,  that 
they  are  not  deferving  of  that  confidence  which  is  fo  generally  and  implicitly  placed  ia 
them.  The  production  of  heat,  ad  libitum,  by  fridion  or  percuffion  between  folid  bodies, 
does,  however,  admit  of  an  eafy  explanation,  without  being  driven  to  the  neceffity  of 
making  caloric  a  non-entity,  or  heat  a  particular  kind  of  motion  t,  propagated  in  fuch  a 

particular 
•  Philof.  Journal,  11.  lOG. 

f  The  prodigious  quantity  of  heat  which  follows  from  an  apparently  rainute  aftion,  has  always  been  con- 
fidered  as  a  ftrong  argument  againft  the  hypothefis,  that  heat  is  mere  motion  ;  but,  upon  clofe  examination,  it  r» 
found  to  apply  to  both  theories.  If  a  very  minlite  portion  of  a  large  mafs-of  oxygen  gas  and  carbon  be  ^a/is/od 
Jlnle  of  •vibration  (or  heated),  and  the  combination  of  this  firft  portion  be  fucceeded  by  vibrations  nnd  combina- 
tions of  the  remaining  parts  of  the  mafs,  we  fhall  be  led  to  inveftigate  the  attraflive  and  repulfive  powers  con- 
c?nied  in  the  phenomena,  and  fhall  in  all  probability  find  the  tafk  by  no  means  eafy.  But  will  our  difficulties" 
be  alleviated  or  removed  by  fuppofing  the  prefence  of  a  third  fubftance  (caloric)  in  previous  combination  with 
the  oxygen,  which  will  certainly  demand,  an  exhibition  of  fimilar  powers  to  account  for  its  tranfition  ?  What- 
ever may  be  the  fuppofcd  play  of  the  affinities  or  powers  tottb  caloric,  it  feems  probable  tliat  the  mere  theory 
might  be  conftrufted  as  well  ( I  do  not  fay  better)  ivilhout  it. 

It  has  been  faid  that  latent  motion  (or  heat)  is  an  abfurdity,  as  in  terms  indeed  it  is ;  but  this  might  be  ex- 
plained in  a  variety  of  ways.  Caloric  is  abforbed,  or  motion  is  accumulated,  in  certain  procef&s.  Slight  inci- 
dents, not  commenfiirate  to  the  clFefl,  fet  them  free.  He  who  fcts  the  catch  of  the  pile-engine  at  liberty,  or  dif- 
charges  a  crofs-bow,  or  breaks  the  tail  of  Prince  Rupert's  drop,  or  communicates  a  fpark  to  a  powder-maga- 
zine,  may  be  faid  to  give  effeft  to  latent  motion,  or  rather  to  deftroy  the  equilibrium  of  forces  generated  by 
£Qrm<:r  clForts,  far  fuperior  to  that  employed  to  fet  thdm  at  liberty. 

3  F  a  -  Though 


40O  On  the  Chemical  Prepertiei  aitrlluUd  it  Light. 

particular  kind  of  manner,  that  the  motion  of  a  (ingle  fpark  of  fire,  direflcd  Into  a  powder- 
magazine,  will  not  only  give  motion  to  the  building  itfelf,  and  its  contents,  but  will  alfo 
ihake  a  county ! 

Should  this  letter  be  thought  unworthy  of  attention,  or  unfit  for  the  public  eye ,  I  could 
wifli,  however,  that  you  would  oblige  me  fo  far,  if  convenient,  as  to  tranfmit  it  to  Dr.  Pear- 
fon.  I  have  the  higheft  opinion  of  his  chemical  knowledge,  as  well  as  of  the  liberality  of 
his  principles  ;  and  though  I  have  plainly  pointed  out  fome  parts  of  his  writings  which  I 
think  erroneous,  I  ftill  hold  him  no  lefs  in  eftimation.  My  only  motive  in  making  the  ob« 
jeftions  and  remarks  which  I  have,  is,  if  poflible,  to  arrive  at  truth. 

I  am,  with  grateful  efteem  for  the  valuable  information  which  1  have  repeatedly  received 
from  your  labours  in  the  fields  of  fcience,  Sir, 

Your  moll  obedient  fervant, 
Nov.  1 6,  1798. 

A  conjlant  Reader  of  your  valuable  Publications. 

Though  I  have  Rated  a  few  fafts  and  obfervations,  I  by  no  means  wifli  re  be  thought  a  maintaincr  of  any 
of  the  theories  alluded  to  in  the  text  or  the  notes. — None  of  them  appear  to  me  to  be  eftablillved  upon  indubi- 
table fafts. 


I 


V. 

An  inquiry  concerning  the  Chemical  Properties  that  have  been  attributed  to  Light,     B^ 
Benjamin,  Count  of  Rumfordy  F.R.S.  M.R.I.  A* 


N  the  fecond  part  of  my  feventh  effay,  (on  the  propagation  of  heat  in  fluids,)  I  have  men- 
tioned the  reafons  which  had  induced  me  to  doubt  of  the  exiftence  of  thofe  chemical  pro- 
perties in  light  that  have  been  attributed  to  it,  and  to  conclude,  that  all  thofe  vifible  changes 
produced  in  bodies  by  expofure  to  the  a£tion  of  the  fun's  rays,  are  effedted,  not  by  any 
chemical  combination  of  the  matter  of  light  with  fuch  bodies,  but  merely  by  the  heat  which 
is  generated,  or  excited,  by  the  light  that  is  abforbed  by  them. 

As  the  decifion  of  this  queftion  is  a  matter  of  great  importance  to  the  advancement  of 
fcience,  and  particularly  to  chemiftry,  and  as  the  fubjeft  is  in  many  refpedts  curious  and 
interefting,  it  has  often  employed  my  thoughts  in  my  leifure  hours;  and  I  have  fpent  much. 
time  in  endeavouring  to  contrive  experiments,  from  the  unequivocal  refults  of  which  the 
truth  might  be  made  to  appear.  Though  I  have  not  been  fo  fuccefsful  in  thefe  itivefliga- 
tions  as  1  could  wifli,  yet  I  cannot  help  flattering  myfelf,  that  an  account  of  the  refults  of 
fome  of  my  late  experiments  will  be  thought  fulBciently  interefting  to  merit  the  attention 
of  the  Royal  Society. 

Having  found  that  gold,  or  filver,  might  be  melted  by  the  heat  (invifible  to  the  fight) 
which  exifts  in  the  air,  at  the  diftance  of  more  than  an  inch  above  the  point  of  the  flame 
of  a  wax-candle,  (fee  my  feventh  eflay,  part  II.  page  350.-t-)  I  was  curious  to  know  what  cf- 
feft  this  heat  would  produce  on  the  oxides  of  thofe  metals. 

Experiment  No.  I.  Having  evaporated  to  drynefs  a  folution  of  fine  gold  in  aqua  regia,  I 
diflfolved  the  refiduum,  in  juft  as  much  diftilled  water  as  was  necefl"ary  in  order  that  the  fo- 

*  Philof.  Tranf.  J 798,  p.  449.  t  OrPhilofi  Journal,  II.  165. 

lution 


Oft  ihe  Chemical Properiks  aiirihutedto  L'tghi.  '401 

lution  (which  was  of  a  beautiful  yellow  colour)  might  not  be  difpofed  to  cryftallize ;  and, 
wetting  the  middle  of  a  piece  of  white  taffeta  riband,  i^  inch  wide,  and  about  eight  inches 
long,  in  this  folution,  I  held  the  riband,  with  both  my  hands,  ftretched  horizontally  over 
the  clear  bright  flame  of  a  wax  candle ;  the  under  fide  of  the  riband  being  kept  at  the  dif- 
tance  of  about  i|  inch  above  the  point  of  the  flame.  The  refult  of  this  experiment  was 
very  ftrilcing.  That  part  of  the  riband  which  was  directly  over  the  point  of  the  flame,  be- 
gan almoft  immediately  to  emit  fteam  in  denfe  clouds  j  and,  in  about  10  feconds,  a  circular 
fpot,  about  i  of  an  inch  in  diameter,  having  become  nearly  dry,  a  fpot  of  a  very  fine  pur- 
ple colour,  approaching  to  crimfon,  fuddeniy  made  its  appearance  in  the  middle  of  it,  and, 
fpreading  rapidly  on  all  fides,  became,  in  one  or  two  feconds  more,  nearly  an  inch  in  dia- 
meter. 

By  moving  the  riband,  fo  as  to  bring,  in  their  turns,  all  the  parts  of  it  which  had  been 
wetted  with  the  folution  to  be  expt)fed  to  the  aftion  of  the  current  of  hot  vapour  that  arofe 
from  the  burning  candle,  all  thofe  parts  which  had  been  fo  wetted,  were  tinged  with  the 
fame  beautiful  purple  colour. 

This  colour,  which  was  uncommonly  brilliant,  pafled  quite  through  the  riband,  and  I 
found  the  ftainto  be  perfe£lly  indelible.  1  endeavoured  to  walh  it  out ;  but  nothing  1  ap- 
plied to  it,  and  among  other  things  I  tried  fuper- oxygenated  marine  acid,  appeared  in  the 
fmalleft  degree  to  diminifh  its  luftre.  The  hue  was  not  uniform,  but  varied  from  a  light 
crimfon  to  a  very  deep  purple,  approaching  to  a  reddifli  brown. 

I  fearched,  but  in  vain,  for  traces  of  revived  gold,  in  its  reguline  form  and  colour  ;  but, 
though  I  could  not  perceive  that  the  riband  was  gilded,  it  had  all  the  appearance  of  being 
covered  with  a  thin  coating  of  the  mod  beautiful  purple  enamel,  which,  in  the  fun,  had  % 
degree  of  brilliancy  that  was  fometimes  quite  dazzling. 

Experiment  No.  2.  A  piece  of  the  riband  which  had  been  wetted  with  the  aqueous 
folution  of  the  oxide,  was  carefully  dried  in  a  dark  clofet,  and  was  then  expofed,  dry, 
over  the  flame  of  a  burning  wax  candle.  The  part  of  the  riband  which  had  been  wetted 
with  the  folution  (and  which  on  drying  had  acquired  a  faint  yellow  colour)  was  tinged  of 
the  fame  bright  purple  colour  as  was  produced  in  the  lalt-mentioned  experiment,  when  the 
riband  was  expofed  wet  to  the  adlion  of  the  heat*. 

.  Experiment  No.  3.  A  piece  of  the  riband  which  had  been  wetted  with  the  folution, 
and  dried  in  the  dark,  was  now  wetted  with  diftilled  water,  and  expofed  wet  to  the 
a£lion  of  the  afcending  current  of  hot  vapour  which  arofe  from  the  burning  candle :  the 
purple  flain  was  produced  as  before,  which  extended  as  far  as  the  riband  had  been  wetted 
with  the  folution,  but  no  farther. 

I  afterwards  varied  this  experiment  in  feveral  ways,  fometimes  ufing  paper,  fome- 
times fine  linen,  and  fometimes  fine  cotton  cloths,  inllead  of  the  filk  riband  ;  but  nearly  the 
fame  tinge  was  produced,  whatever  the  fubftance  was  that  was  made  to  imbibe  the  aqueous 
folution  of  the  metallic  oxide. 

Similar  experiments,  and  with  fimilar  refults,  were  likewife  made  with  pieces  of  riband, 

•  We  ftall  hereafter  find  reafon  to  conclude,   that  the  fuccefs  of  this  experiment,  or  the  appearance  of  the-  ■ 
purple  tinge,   was  owing  to  the  watery  vapour  which  exiftcd  in  the  hot  current  that  afccndcd  from  tlxe  fiame  uf 
the  candle,    R. 

fine 


jjtJt  On  the  Chemical  Properties  attrlbuteltg  Light. 

iine  linen,  cotton,  paper,  &c.  wetted  in  an  aqueous  folutlon  of  nitrate  of  filver  ;  with 
this  ditlerence,  however,  that  the  tinge  produced  by  this  metallic  oxide,  inflead  of  being 
of  a  deep  purple,  inclining  to  crimfon,  was  of  a  very  dark  orange  colour,  or  rather  of  a 
yellowifii  brown. 

In  order  to  difcover  whether  the  purple  tinge,  in  the  experiments  with  the  oxide  of  gold, 
was  occafioned  by  the  heat  communicated  by  the  afcending  current  of  hot  vapour,  or  by  the 
light  of  the  candle,  I  made  the  following  experiment,  the  rcfult  of  which  I  conceive  to 
Iiave  been  decifive. 

Experiment  No.  4.  A  piece  of  riband  was  wetted  with  the  aqueous  folution  of  the  oxide 
of  gold,  and  held  vertically  by  the  fide  of  the  clear  flame  of -a  burning  wax  candle,  at  the 
diftance  of  kfs  than  half  an  inch  from  the  flame. 

The  riband  was  dried,  but  its  colour  was  not  in  the  fmallefl  degree  changed. 

When  it  was  held  a  few  feconds  within  about  i  of  an  inch  of  the  flame,  a  tinge  of  a^ 
mod  beautiful  crimfon  colour,  in  the  form  of  a  narrow  vertical  ftripe,  was  produced. 

The  heat  which  exifted  at  that  diftance  from  the  flame,  on  theftdeofit,  where  this  co- 
loured fliipe  was  produced,  was  fufliciently  intenfe,  as  I  found  by  experiment,  to  melt 
V€ry  fine  filver  wire,  flatted,  fuch  as  is  ufed  in  making  filver  lace. 

:,  The  obje£ls  I  had  in  view  in  the  following  experiments  are  too  evident  to  require  any 
paVticular  explanation. 

Experiment  No.  5.  Two  like  pieces  of  riband  were  wetted  at  the  fame  time  in  the  folution, 
and  fufpended,  while  wet,  in  two  thin  phials,  A  and  B,  of  very  tranfparent  and  colourlefs 
glafs  ;  the  mouths  of  the  phials  being  left  open.  Both  thefe  phials  were  placed  in  a  M'indow 
which  fronted  the  fouth  ;  that  diftinguiflicd  by  the  letter  A  being  expofed  naked  to  the 
dire£1;  rays  of  a  bright  fun  ;  while  B  was  inclofed  in  a  cylinder  of  paft:eboard,  painted  black 
within  and  without,  and  clofed  with  a  fit  cover,  and  confequently  remained  in  perfedb 
darknefs. 

In  a  very  few  minutes,  the  riband  in  the  phial  A  began  fenfibly  to  change  its  colour, 
and  to  take  a  purple  hue ;  and,  at  the  end  of  five  hours,  it  had  acquired  a  deep  crimfon 
tint  throughout. 

The  phial  B  was  expofed  in  the  window,  in  its  dark  cylindrical  cover,  three  days  5  but 
ihere  was  not  the  fmalleft  appearance  of  any  change  of  colour  in  the  filk. 

Experiment  No.  6.  Two  fmall  parcels  of  magnefta  alba,  in  an  impalpable  powder, 
(about  half  as  much  In  each  as  could  be  made  to  lie  on  a  fliilling,)  were  placed  in  heaps, 
in  two  china  plates,  A  and  B,  and  thoroughly  moiftened  with  the  before-mentioned 
aqueous  folution  of  the  oxide  of  gold.  Both  plates  were  placed  in  the  fame  window  ;  the 
moiftened  earth  in  the  plate  A  being  expofed  naked  to  the  fun's  rays  ;  while  that  in  the 
plate   B  was  exadly  covered  with  a  tea-cup,  turned  upfide  down,  which  excluded  all 

light. 

The  magnefta  alba  In  the  plate  A,  which  was  expofed  to  the  flirong  light  of  the  fun, 
began  almofl;  immediately  to  change  colour,  taking  a  faint  violet  hue,  which  by  degrees 
became  more  and  more  intenfe,  and  in  a  few  hours  ended  in  a  deep  purple  ;  while  that  in 
the  plate  B,  which  was  kept  in  the  dark,  retained  the  yellowiih  caft  it  had  acquired  from 
the  folution,  without  the  fmalleft  appearance  of  change. 

Experiment  No,  7,     A  fmall  parcel  of  magnefta  alba,  placed  on  a  china  plate,  having  been  ' 

moiftened 


On  the  Chemical  Prtperties  aitrihuted  to  Light,  403 

moiftened  with  the  aqueous  folution  of  the  oxide  of  gold,  and  thoroughly  dried  in  a  dark 
clofet,  was  now  expofed,  in  this  dryjiate,  to  the  aftion  of  the  dire<5t  rays  of  a  very  bright 
■fun. 

It  had  been  expofed  to  this  ftrong  light  above  half  an  hour,  before  its  colour  began  to 
hcfcnftbly  changed  \  and,  at  the  end  of  three  hours,  it  had  acquired  only  a  very  faint  violet 

hue. 

Being  now  thoroughly  wetted  with  diftilled  water,  it  changed  colour  very  rapidly,  and 
foon  came  to  be  of  a  deep  purple  tint,  approacliing  to  crimfon. 

Experiment  No.  8.  A  piece  of  white  taffeta  riband,  which  had  been  wetted  with  the 
folution,  and  thoroughly  dried  in  the  dark,  was  fufpended  in  a  clean  dry  phial  of  very  fine 
tranfparent  glafs ;  and  the  phial,  being  well  flopped  with  a  dry  cork,  was  expofed  to  the 
ftrong  light  of  a  bright  fun. 

After  the  riband  had  been  expofed,  in  this  manner,  to  the  aflion  of  the  fun's  direft 
rays  about  half  an  hour,  there  were  here  and  there  fome  faint  appearances  of  a  change  of 
its  colour  ;  but  it  fliowed  no  difpofitlon  to  take  that  deep  purple  hue  which  the  riband  had 
always  acquired,  when  expofed  to  the  light  in  the  preceding  experiments. 

On  taking  the  riband  out  of  the  phial,  and  wetting  it  thoroughly  with  diftilled  water, 
and  expofing  it  again,  while  thus  wetted,  to  the  fun's  rays,  it  almoft  inftantly  began  to 
change  colour,  and  foon  became  of  a  deep  purple  tint ;  but,  though  I  examined  the 
furface  of  the  riband  with  the  utmoft  care,  and  with  a  good  lens,  both  during  the 
experiment  and  after  it,  I  could  not  perceive  the  fmalleft  particle  of  revived  gold,  nor  did 
I  fee  any  veflige  remaining  that  appeared  to  Indicate  that  any  had  in  fa£1:  been  revived. 

This  experiment  was  repeated  feveral  times,  and  always  with  refults  which  led  me  to 
conclude,  (what  indeed  was  reafonable  to  expeft,)  that  light  has  little  efFeil  in  changing 
the  colour  of  metallic  oxides,  as  long  as  they  are  in  a  J] ale  of  cryjlalli-zation. 

The  heat  which  is  generated  by  the  abforption  of  the  rays  of  light  muft  neceflarily,  at  the 
moment  of  its  generation  at  leaflr,  exift  in  almoft  infinitely  fmall  fpaces  ;  and  confequently, 
it  is  only  in  bodies  that  are  inconceivally  fmall  that  it  can  produce  durable  effedls,  in  any 
degree  indicative  of  its  extreme  intenfity. 

Perhaps  the  particles  of  the  oxide  of  gold  diffblved  in  water  are  of  fuch  dimenfions ; 
and  it  Is  very  remarkable,  that  the  colours  produced,  in  fome  of  my  experiments  on  white 
ribands,  by  means  of  an  aqueous  folution  of  the  oxide  of  gold,  are  preclfely  the  fame  as 
are  produced  from  the  oxide  of  that  metal,  by  enamellers,  in  the  intenfe  heat  of  their 
furnaces. 

As  the  colouring  fubft:ance  is  the  fame,  and  as  the  colours  produced  are  the  fame,  why 
fhould  we  not  conclude  that  the  effe£i:s  are  produced  in  both  thcfe  cafes  by  the  fame  means, 
that  is  to  fay,  by  the  agency  of  heat  ?  or,  in  other  words,  and  to  be  more  explicit,  by 
expofing  the  oxide  in  a  certain  temperature,  at  which  it  becomes  difpofed  to  vitrify,  or  ta 
undergo  a  change  in  regard  to  the  quantity  of  oxygen  with  which  it  is  combined  ? 

But  the  refults  of  the  following  experiments  afford  ftill  more  fatisfa£lory  information,, 
refpefting  the  intenfity  of  the  heat  generated  in  all  cai'es  where  light  is  abforbed,  and  the 
ftriking  effedts  which,  under  certain  circuraftances,  it  is  capable  of  producing. 

The  facility  with  which  moft  of  the  metallic  oxides  are  reduced,  in  the  dry  way,  by 

means 


-404.  Cn  the  Chemical  Properties  aiirihuied  to  Light. 

•means  of  charcoal,  (hows  that,  at  a  certain  (high)  temperature,  oxygen  Is  difpofed  to  quit 
thofe  metals,  in  order  to  form  a  chemical  union  with  the  charcoal,  or  at  leaft  with  fome 
one  of  its  conftituent  principles,  if  it  be  a  compound  fubftance ;  and  hence  I  concluded, 
■that  gold  might  be  revived,  i/i  the  moifl  -way,  by  means  of  charcoal,  from  a  folution  of  its 
oxide  in  water,  were  it  poffible,  under  fuch  circumftances,  to  communicate  to  the  charcoal, 
and  to  the  oxide,   at  the  fame  time,  a  degree  of  heat  fufficient  for  that  purpofe. 

To  fee  if  this  might  not  be  done  by  means  of  light,  I  made,  or  rather  repeated,  the 
following  very  interefting  experiment : 

Experiment  No,  9.  Into  a  thin  tube  of  very  fine  colourlefs  glafs,  10  inches  long,  and  -n» 
of  an  inch  in  diameter,  clofed  hermetically  at  its  lower  end,  I  put  as  many  pieces  of 
charcoal,  about  the  fize  of  large  peas,  as  filled  the  tube  to  the  height  of  two  inches  ;  and, 
having  poured  on  them  as  much  of  the  aqueous  folution  of  nitro-muriate  of  gold  as  nearly 
covered  them,  expofed  the  tube,  with  its  contents,  to  the  adiion  of  the  dire£t  rays  of  a 
very  bright  fun. 

In  lefs  than  half  an  hour,  fmall  fpecks  of  revived  gold,  in  all  Its  metallic  fplcndour, 
began  to  make  their  appearance  here  and  there  on  the  furf'ace  of  the  charcoal ;  and,  in  fix 
hours,  the  folution,  which  at  firft  was  of  a  bright  yellow  colour,  became  perfeflly 
colourlefs,  and  as  clear  and  transparent  as  the  purest  water. 

The  furface  of  the  charcoal  was,  in  fevcral  places,  nearly  covered  with  fmall  particles 
of  revived  gold  ;  and  the  infide  of  the  glafs  tube,  in  that  part  where  it  was  in  contadl:  with 
the  upper  furface  of  the  contained  liquid,  was  moft:  beautifully  gilded. 

This  gilding  of  the  tube  was  very  fplendid,  when  viewed  by  refledled  light ;  but,  when 
the  tube  was  placed  between  the  light  and  the  eye,  it  appeared  like  a  thin  cloud,  of  a 
grecnifli  blue  colour,  without  the  fmalleft  appearance  of  any  metallic  fplendour. 

From  the  colour,  and  apparent  denfity  of  this  cloud,  I  was  induced  to  conclude,  that 
the  gilding  on  the  glafs  was  lefs  than  one  millionth  part  of  an  inch  in  thicknefs. 

This  interefting  experiment  was  repeated  fix  times,  and  always  with  nearly  the  fame 
refult.  The  gold  was  completely  revived  in  each  of  them,  and  the  folution  left  perfedtly 
colourlefs :  in  moft  of  the  experiments,  however,  the  fides  of  the  _glafs  were  not  gilded,  all 
the  revived  gold  remaining  attached  to  the  furface  of  the  charcoal. 

In  two  of  thefe  experiments,  I  made  ufe  of  pieces  of  charcoal  which  had  been  previoully 
boiled  feveral  hours  in  a  large  quantity  of  diftilled  water,  and  which  were  introduced  luet, 
■znAhot,  into  the  tube,  and  immediately  covered  by  the  folution,  to  prevent  them  from  im- 
bibing any  air ;  and,  in  different  experiments,  the  folution  was  ufed  of  different  degrees  of 
ftrength. 

I  plainly  perceived  that  the  experiment  fucceeded  beft,  that  is  to  fay,  that  the  gold  was 
fooneji  revived,  in  thofe  cafes  in  which  the  folution  was  moji  diluted :  one  of  the  experiments, 
however,  and  which  fucceeded  perfectly,  was  made  with  the  folution  fo  much  condenfed, 
that  It  was  nearly  at  the  point  at  which  it  became  difpofed  to  cryftallize  *. 

*  This  agrees  perfcflly  with  the  refults  of  fimilar  experiments  made  by  the  ingenious  and  lively 
Mrs.  FuLHAME.     (See  her  Effay  on  Combuftion,  page  124.) 

It  was  on  reading  her  book  that  I  was  induced  to  engage  in  thefe  inveftigations  j  and  it  was  by  her  experi- 
ments that  raoft  of  the  foregoing  experiments  were  fuggefted.    R. 

7  On 


On  the  Chemical  Properties  aitriluted  to  Ligfit.  4©e 

On  examining,  with  a  good  microfcope,  the  particles  of  revived  gold  which  remained 
attached  to  the  furface  of  the  charcoal,  after  it  had  been  dried,  I  found  them  to  confift  of 
an  infinite  number  of  fmall  fcales,  feparated  from  each  other ;  not  very  highly  poliflied, 
but  pofleffing  the  true  metallic  fplendour,  and  a  very  deep  and  rich  gold  colour. 

The  gold  which  attached  itfelf  to  the  infide  of  the  glafs  tube,  was  in  the  form  of  a  ring, 
about  Tg  of  an  inch  wide,  (badly  defined  however  below,)  and  adhered  to  the  glafs  with  fo 
much  obftinacy,  as  not  to  be  removed  by  rinfing  out  the  tube  a  great  number  of  times  with 
water  ;  it  had,  as  has  already  been  obferved,  a  very  high  polifh,  when  feen  by  reflefted 
ligfit. 

Thofe  who  enter  into  the  fpirit  of  thefe  inveftigations,  will  eafily  imagine  how  impatient 
I  muft  have  been,  after  feeing  the  refults  of  thefe  experiments,  to  find  out  whether  gold 
could  be  revived  from  this  aqueous  folution  of  its  oxide  by  means  of  charcoal,  nvithout  the 
ajfijlance  of  lights  and  merely  by  fuch  a  degree  of  equaf  heat  as  could  be  given  to  it  in  the 
dark.     To  determine  that  important  queftion,  the  following  experiment  was  made. 

Experiment  No.  lo. — A  cylindrical  glafs  tube,  -^%  of  an  inch  in  diameter,  and  lo  inches 
long,  clofed  hermetically  at  its  lower  end,  and  containing  a  quantity  of  a  diluted  aqueous 
folution  of  the  oxide  of  gold,  mixed  with  charcoal  in  broken  pieces,  about  the  fize  of  large 
peas,  was  put  into  a  fit  cylindrical  tin  cafe,  which  was  nicely  clofed  with  a  fit  cover;  and 
the  glafs  tube,  with  its  contents,  fo  (hut  up  in  the  dark,  was  expofed  two  hours.  In  the 
temperature  of  2 1  o°  of  Fahrenheit's  fcale. 

On  taking  the  glafs  tube  out  of  its  tin  cafe,  I  found  the  {olution  perfe^ly  cokurk/s,  and 
the  revived  gold  adhering  to  the  furface  of  the  charcoal. 

On  repeating  the  experiment,  and  ufing  the  folution  nearly  faturated  with  the  oxide,  the 
refult  was  precifely  the  fame ;  the  folution  being  found  perfeQly  colourlefs,  and  the  re- 
vived gold  adhering  to  the  furface  of  the  charcoal. 

I  own  fairly,  that  the  refults  of  thefe  experiments  were  quite  contrary  to  my  expefla- 
tlons,  and  that  I  am  not  able  to  reconcile  them  with  my  hypothefis,  refpefting  the  caufe* 
of  the  reduftion  of  the  oxide.  In  the  foregoing  experiments  ;  but,  whatever  may  be  the  fate 
of  this,  or  of  any  other  hypothefis  of  mine,  I  hope  and  truft  that  I  never  (hall  be  fo  weak  as 
to  feel  pain  at  the  difcovery  of  truth,  however  contrary  It  may  be  to  my  expedlatlons  ;  and 
ftill  lefs,  to  feel  a  fecret  wi(h  to  fupprefs  experiments,  merely  becaufe  their  refults  militate 
againft  my  fpeculative  opinions. 

It  Is  proper  I  (hould  obferve,  that  the  charcoal  ufed  in  this  laft-mentloned  experiment 
had  been  boiled  two  hours  In  diftllled  water  ;  by  which  means  Its  pores  had  been  fo  com- 
pletely filled  with  that  fluid,  that  the  pieces  of  it  that  were  ufed  were  fpecifically  heavici; 
than  water,  and  funk  in  it  to  the  bottom  of  the  containing  velTel. 

(To  be  continued.) 


Vol.  II.— Dec.  J  798.  3G  Vl.  Expe. 


406  Comparative  ^rialyfes  of  Gums  and  Sugar. 


VI. 


Experiments  and  Obfervations  on  the  Nature  of  Sugar,  and  of  Vegetalle  Mu'cUiige.     By  Mr, 
William  CruickSHANK,   Chemijl  to  t^e  Ordnance,  ^c* 


F 


ROM  the  failure  of  thefe  trials  to  convert  mucilages  into  fomething  refembling  fugar, 
we  began  to  fufpe£l  that  they  were  not  fo  fimple  as  had  been  generally  fuppofed.  With  a 
view  to  throw  fome  light  on  this  fubjeft,  the  following  comparative  experiments  were  made  : 

One  ounce  of  powdered  gum  arable  was  introduced  into  a  coated  glafs  retort,  to  which  a 
receiver  with  the  pneumato-chemical  apparatus  was  adapted  :  heat  being  gradually  applied, 
there  came  over  into  the  receiver  3  dr.  30  gr.  of  pyromucous  acid,  mixed  with  a  little  heavy 
empyfeumntic  oil.  After  the  retort  had  been  red-hot  for  fome  time,  it  was  removed,  and  the 
charry  refiduum  which  it  contained  was  found  to  weigh  i  dr.  46  gr.  This  had  a  greyifh  co- 
lour, and  burned  very  flov/Iy ;  but  when  expofed  to  a  flrong  heat  in  an  open  crucible,  is 
left  a  whitifli  powder,  amounting  to  i  o  grains,  which  was  found  to  be  lime  tnixed  with  a 
very  fmnll' proportion  of  calcareous  phofphate. 

The  pyromucous  acid  being  fuper-faturated  with  Hme,  a  ftrong  fmell  of  ammonia  was 
inftantly  perceived  ;  and  a  piece  of  paper  dipped  in  muriatic  acid  being  held  over  the  veflel, 
copious  white  fumes  were  immediately  produced.  This  circumftance  fhews,  that  azote 
forms  a  conftituent  part  of  the  gum. 

There  were  collefted  in  the  pneumato-chemical  apparatus  273  oz.  meafures  of  gas;  of 
this  93  were  carbonic  acid,  and  the  remaining  180,  that  fpecies  of  hydro- carbonate  which 
is  obtained  by  heat  from  moiflened  charcoal. 

Two  meafures  of  this  gas,  well  freed  from  carbonic  aci-d,  were  mixed  with  i^-  of  very 
pure  oxygen  gas,  and  introduced  in  a  ftrong  glafs  jar,  filled  with  and  inverted  over  mer- 
cury :  when  fired  by  the  eleftric  fliock,  they  occupied  the  fpace  of  one  meafure  only  r 
lime  water  being  admitted,  the  whole  was  ablorbed,  except  a  very  fmall  particle,  which  was 
found,  from  the  nitrous  teft,  to  be  pure  air.  From  a  number  of  experiments  we  have 
found,  that  twelve  meafures  of  oxygen  gas,  when  united  with  carbon,  produce  ten  of 
carbonic  acid  gas.  Hence  it  fbllows,  that  the  quantity  of  oxygen  gas  neceflary  to  the  for- 
mation of  carbonic  acid  gas  muft,  in  this  tafe,  have  been  i.i.  meafures,  or  a  little  better  ; 
the  remaining  4  muft  therefore  have  been  confumed  in  the  production  of  water,  and  would 
be  fufficient  to  faturate  .8  of  hydrogen,  equal  in  weight  to  .048  of  a  grain  nearly. 

•  Thefe  Experiments,  &c.  area  continuation  of  the  Refearch  communicated  in  the'  firft  volume  of  this 
Journal,  page  a-^.  In  the  fecond  edition  of  Dr.  Rollo's  Treatife  on  Diabetes  Mellitus  in  which  that  article 
is  reprinted,  and  whence  the  above  is  taken,  there  are  a  few  emendations  in  the  fecond  and  third  parar 
graphs,  as  follow  :  The  fiigar  afforded  £^  drams  of  acid,  which  required  1 50  grains  of  the  alkalme  foiution  to 
faturate  it;  the  charry  refidue  was  5  drams;  and  the  gas. which  ^fcaped  li  drams.  The  gum  arabic  afforded 
7  dr.  40  gr.  of  acid,  which  required  118  grains  of  the  fob:tion  of  pot-afli  to  faturate  it ;  t!;e  charry  refidue 
■was  3  dr.  45  gr.j  and  the  gas  which  efcapcd  5  drams.  Whence  the  fugar  yielded  more  pyromucous  acid  than- 
the  gum,  in  the  proportion  of  150  to  iig. 

The  concluding  paragraph  on  page  341,  beginning,  "  InJefd,  -when  ive  reJleB,"  &c.  is  cancelled,  and  the 
inveftigation  is  continued  as  in  the  text.  The  prefent  article  mtlft  therefore  be  read  as  a  continuation  from 
vol.  L  p.  341,  of  this  Journal..     N., 


Comparative  Atinlyfes  of-Gunu  and  Sugar.  407 

.  Now,  an  ounce  meafure  of  carbonic  actd  gas  weighs  .864.  of  a  grain,  and  this  containt 
.24  of  pure  charcoal :  hence  the  quantity  of  charcoal  to  hydrogen  in  this  inflammable  gas 
muft  be  as  .24  to  .048,  or  5  to  i.  '         .  ■     ' 

But  one  meafure  of  pure  hydro-carbonate,  fuch  as  may  be  obtained  from  the  decompo- 
fition  of  camphor,  by  making  its  vapour  pafs  through  a  red-hot  earthen  tube,  or  from  the 
diftillation  of  animal  fubftances,  opium,  &c.  requires  two  of  pure  air  to  faturate  it  J  an4 
the  quantity  of  carbonic  acid  amounts  to  1.45,  which  makes  the  proportion  of  carbon  to 
hydrogen  as  12  or  1 3  to  i.  Hence  thefe  gafes  differ  materially,  and  ought  not  to  be  con- 
founded :  indeed,  the  difference  between  them  is  manifeft,  from  the  mau^ner  in  which  they 
burn  when  mixed  with  common  air,  and  brought  into  contadl  with  an  ignited  body.  Pure 
hydro-carbonate  burns  flowly,  with  a  perfe£lly  white  flame,  and  never  detonates  :  on  the 
contrary,  the  compound  inflammable  gas  juft  mentioned  burns  rapidly,  with  a  reddifh 
blue  flame,  and  more  or  lefs  of  a  detonation.  We  thought  it  necefTary  to  mention  this 
clrcuraflance,  as  much  qonfufion  might  be  produced  by  applying  the  fame  name  to  fub- 
ftances  confiderably  dilTerent.  It  is  remarkable  that  a;ther,  decompofed  by  heat,  afFordi 
pure  hydro-carbonate,  whilft  alcohol  yields  the  mixed  fpecies. 

But  to  return  : — An  ounce  of  gum  tragacanth  was  fubmitted  In  a  coated  glafs  retort  to 

a  fimilar  procefs,  and  the  products  collefted  were  as  follows : 

dr.     gr. 
Charcoal  remaining  in  the  retort,  -  -  -  i    45 

Pyromucous  acid,  -  -  ,  -  _         _  4      5 

Carbonic  acid  gas,  -  -  -  -  78  oz.  meaC. 

Hydro-carbonate,  -  -  -  -  91  ditto. 

The  charcoal  burned  flowly  with  a  peculiar  phofphorefcent  flame,  and  left  a  white  rc- 
Cduum  of  12  grains,  which  was  found  to  confift  of  lime  mixed  with  a  little  calcareoui 
phofphatc. 

The  pyromucous  acid  being  fuper-faturated  with  lime,  the  quantity  of  ammonia  difcn- 
gaged  appeared  to  be  confiderably  greater  than  from  that  afforded  by  the  gum  arable. 

Having  In  this  way  difcovered  lime  in  both  fpecies  of  gum,  we  were  anxious  to  know  if 
Ais  earth  could  be  detedled  by  reagents,  without  having  recourfe  to  decompofition  by  heat. 
Accordingly,  a  quantity  of  fulphuric  acid  was  dropped  into  a  folution  of  gum  arable  :  after 
{landing  for  fome  hours,  a  number  of  needle-like  cryftals  were  flowly  depofited  :  thefe  be- 
ing feparated  were  difl"olved  in  diftlUed  water ;  to  this  folution  the  oxalate  of  ammonia  was 
added,  when  a  copious  precipitate  of  oxalate  of  lime  Immediately  took  place. 

From  thefe  experiments,  therefore,  it  is  manifeft,  that  gums  confiit  of  oxygen,  hydro- 
gen, carbon,  azote,  and  lime,  with  a  little  phofphoric  acid. 

An  ounce  of  refined  fugar  was  next  introduced  Into  a  coated  retort,  and  the  pneumato- 
chemical  apparatus  applied,  as  in  the  former  experiments.     The  products  obtained  were, 

oz.     dr.     gr. 

Pyromucous  acid,  with  a  drop  or  two  of  empyreumatic  oil,      o    4     30 
Charcoal,         -  -  -  -  -  -020 

Hydro-carbonate,  -  -  .  .  .     1190Z.  meaf. 

Carbonic  acid,         -  -  -  .  -  41  ditto. 

The  pyromucous  acid  being  fuperfaturated  with  lime,  not  the  leaft  veftige  of  ammonl^' 
could  be  -perceived.  Sugaf,  therefore,  does  not  contain  azote ;  ncithtr  does  it  coiitala  IimeV 

3  G  2  for 


4o8  Cofnparatlve  Analyfes  of  Gums  and  Sugar, 

for  the  charcoal,  which  was  of  a  beautifully  black  colour,  burned  out  completely  when  ex» 

pofed  to  a  ftrong  red  heat. 

Being  defirous  of  afcertaining  more  completely  the  difference  between  common  fugar 

and  the  faccharine  matter  fecreted  by  the  breads  of  animals,  an  ounce  of  the  crydalhzed 

fugar  of  milk  was  diftilled  in  an  apparatus  fimilar  to  that  already  defcribed,  and  the  pro- 

du(fls  were  found  to  be, 

oz.    dr.   gr. 

Pyromucous  acid,  mixed  with  a  very  little  empyreumatic  oil,        060 

Charcoal,  with  a  little  phofphate  of  lime,  -  -  010 

Carbonic  acid  gas,  -  -  -  -  31  oz.  meaf. 

Hydro-carbonate,  of  the  fame  nature  with  that  obtained  in 

the  former  experiments,  -  _  _  103  ditto. 

The  charcoal  being  burned  in  an  open  crucible,  there  remained  about  one  grain,  which 
appeared  to  be  phofphate  of  lime  chiefly. 

The  pyromucous  acid  was  next  fuperfaturated  with  lime  ;  but  the  quantity  of  ammonia 
difengaged  was  fo  fmali  that  it  could  with  difficulty  be  detected:  there  appeared,  however, 
to  be  a  very  little. 

Hence,  then,  it  would  feem  that  this  animal  fugar,  contrary  to  what  might  be  expefted, 
contains  hardly  any  azote. 

It  would  appear  alfo,  that  it  contains  lefs  charcoal,  and  more  oxygen,  than  common 
fugar. 

In  order  to  invefligate  ftilj  further  the  nature  of  thefe  fubflances,  we  endeavoured  to- 
afcertain  the  quantity  of  oxalic  bafis  or  radical  contained  in  each,  or  how  much  oxalic  acid 
they  would  afford  when  treated  with  an  equal  proportion  of  the  nitrous  acid. 

An  ounce  of  fugar  was  added  to  fix  ounces  of  the  concentrated  nitrous  acid,  diluted  with 
an  equal  bulk  of  water.  When  the  adlion  had  in  a  great  meafure  ceafed,  heat  was  applied, 
and  the  evaporation  continued  until  the  liquor  was  reduced  to  about  an  ounce  by  mea- 
fure :  after  this  had  cooled,  the  cryftals  were  feparated  by  fdtration,  and  the  remaining 
fluid  again  evaporated,  until  the  whole,  when  cold,  fliot  into  a  mafs  of  cryftals,  leaving 
only  a  few  drops  which  refufed  to  cryftallize.  Thefe  cryftals  being  colle<n:ed,  and  well  dried 
on  blotting  paper,  amounted  to  4  dr.  20  gr.  or  a  little  better  than  half  the  weight  of  the 
fugar  employed. 

An  ounce  of  gum  arable  was  next  treated  with  an  equal  proportion  of  nitrous  acid  pro- 
perly diluted  :  the  quantity  of  cryftals  colleded  amounted  to  J  dr.  36  gr.;  but  in  this  in- 
ftance,  the  laft  cryftals  obtained  were  mixed  with  an  infoluble  white  powder,  which,  being 
feparated  from  the  oxalic  acid  by  the  addition  of  diftilled  water,  amounted  to  6  gr.  and 
was  found  to  be  oxalate  of  lime.  The  pure  acid,  therefore,  did  not  exceed  3  dr.  and  a. 
half.  An  equal  quantity  of  gum  tragacanth  afforded,  by  the  fame  procefs,  3  dr.  10  gr. 
of  oxalic  acid,  and  10  gr.  oxalate  of  lime. 

An  ounce  of  the  fugar  of  milk  was  alfo  treated  in  a  fimilar  manner,  with  fix  ounces  of 
the  concentrated  nitrous  acid  properly  diluted,  and  there  were  obtained  in  all  3  dr.  48  gr» 
Thefe  cryftals,  however,  were  mixed  with  a  white  powder,  which,  being  but  a  little  fo- 
luble  in  water,  was  readily  feparated  :  it  amounted  to  30  gr.  and  appeared  to  be  the  fac- 
eholai^ic  acid  of  Scheeici  hence  the  pure  oxalic  acid  did  not  exceed  3  dr,  18  gr. 


Cmpsnent  Parts  of  Saccharine  and  Mucilagitioui  Subflancef.  409 

An  ounce  of  honey  yielded,  by  a  fimilar  procefs,  4  dr.  4  gr.  of  pure  Oxalic  acid,  but 
exhibited  no  figns  of  faccholadlic  acid. 

The  following  Table  will  flievv,  at  one  view,  the  different  produ£ls  refulting  from  de- 
ftruflive  diftillation,  with  their  relative  proportions,  and  likewife  thofe  obtained  by  the 
nitrous  acid. 


Subftances  employed, 
I  01.  of  each. 

Products  obt 

lined  by  Heat. 

Produds  obtained  by 
Nitrous  Acid. 

Charcoal,  &c. 

Pyromucous 
Acid,  &c. 

Carbonic  Acid 
Gas. 

Hydrocarbon  • 
ate. 

Oxalic 

oz.     dr. 
0      4 

Acid. 

Othei  Subftances. 

Sugar,     -     -     - 

oz.     dr.      gr. 

0     a       0 

oz.     dr.      gi. 
0      4      30 

oz.  meafurcs. 
41 

oz.  meafurcs. 
119 

20 

None. 

Honey, 

' 

0 

4 

4 

None. 

Sugar  of  Milk, 

010 

060 

3' 

i°3 

0 

3 

18 

30  grains  of  fac- 
cholaftic  acid. 

Gum  Arabic,    - 

0    l    36 

and  lime  10 

0.   3     30 
with  fome 
ammonia. 

93 

180 

0 

3 

30 

Oxalate  of  lime, 
6  grains. 

0      I     46 

GumTragacanth, 

0     I     33 
and  lime  12 

°.   4.     5 
with  fome 
ammonia. 

73 

91 

0 

3 

10 

Oxalate  of  lime, 
10  grains. 

0     I     45 

From  thefe  experiments  it  would  appear,  that  fugar  confifts  merely  of  carbon,  hydro- 
gen, and  oxygen  ;  and  that  gum  differs  from  fugar,  not  only  in  containing  a  lefs  propor- 
tion of  oxygen,  but  alfo  by  its  combination  with  lime  and  azote  ;  and  that  the  fugar  of 
milk  differs  from  both,  as  it  contains  the  radical  of  the  facchola£tic  acid  :  in  other  refpetls, 
however,  it  approaches  very  nearly  to  the  nature  of  vegetable  fugar.  Does  the  milk  of  car- 
nivorous and  graminivorous  animals  yield  the  fame  proportion  of  this  acid  ?  and  is  this  fu- 
gar itfelf  always  of  the  fame  nature  I 

From  the  well  known  fafts  refpe6iing  vinous  fermentation,  there  is  now  leafon  to  fup- 
pofe,  that  no  fubftances,  but  thofe  which  confift  fimply  of  carbon,  hydrogen,  and  oxy- 
gen, are  fufceptible  of  it,  and  that  an  union  virith  a  fourth  changes  the  nature  of  the  com- 
pound fo  much  as  to  render  this  procefs  imprafticable. 

With  a  view  to  throw  fome  light  on  this  obfcure  fubjeft,  the  following  experiments 
were  made  : 

Attgufi  4,  1798. — An  ounce  of  fugar  difiblvedin  5  ounces  of  water  was  digefled  with  a» 
little  frefli  flaked  quicklime,  in  a  m.oderate  heat,  for  about  15  minutes;  the  folution  was  then, 
filtered,  and  about  2  drachms,  by  meafure,  of  good  yeafl;  added ;  the  veflel  and  mixturCy 
weighing  17  oz.  2  dr.  were  introduced  below  a  large  glafs  bell. 

There  was  placed  clofe  to  it,  as  a  flandard,  another  veffel,  containing  an  ounce  of  fugar 
dllTolvedin  5  ounces  of  warm  water,  and  to  which  an  equal  quantity  of  yeaft  was  added.  This- 
Ycflel  and  mixture,  which  weighed  together  17  oz.   i  drachm,  20  grains,  were  likewife 

placed 


4IO  Exper'mints  on  Fermentation. 

placed  under  a  glafs  bell.  The  temperature  of  the  room  during  the  whole  of  this  experi- 
ment was  rather  high,  and  varied  froni  68°  to  75°  ot.Fahrenlicit. 

The  laft  mixture  began  to  ferment  in  12  hours,  and  in  24  the  procefs  feemed  very  brifk, 
.much  water  now  condenfing  on  the  fides  of  the  bell.  In  five  days  the  procefs  began  to  fub- 
fuie  ;  in  feven,  the  yealt  fell  to  the  bottom,  and  the  liquor  became  clear.  The  mixture, 
at  this  time,  fmelled  ftrongly  of  beer  turned  a  little  four,  although  it  ftill  tailed  fweet- 
ifh.  It  was  fuffered  to  remain  until  the  28th,  when  it  was  removed  from  the  bell  and 
weighed,  and  the  lofs  was  found  to  exceed  three  drachms  :  it  now  tailed  much  like  a  mixture 
of  flrong  vinegar  and  honey.  During  the  whole  of  this  period,  amounting  to  ^14  days, 
the  mixture,  containing  the  fugar  digefted  with  the  lime,  never  fliewed  the  lead  appear- 
ance of  fermentation,  nor  was  there  any  moifture  condenfed  on  the  fides  of  the  bell.  The 
veflel  and  mixture  being  now  weighed,  the  lofs  amounted  to  two  drachms  nearly;  the  li- 
quor fmelled  very  mully,  and  had  a  rough  aflringcnt  tafte,  mixed  with  fweetnefs,  but  was 
not  in  the  leaft  acid.  In  this  inllance  the  yeall  fell  to  the  bottom  very  foon,  the  liquor 
continued  more  or  lefs  mouldy,  and  became,  at  lall,  a  little  mouldy  at  the  top. 

We  next  digefted  an  ounce  of  fugar,  diflblved  in  five  ounces  of  water,  with  a  little  pot- 
afh,  and  to  the  filtered  folution  added  about  two  drachms  of  very  good  yeall.  This  mix- 
ture was  expofed  in  an  open  veflel  to  a  tem.perature  of  about  65°;  and  another  veflel,  con- 
taining a  folution  of  an  equal  quantity  of  fugar,  mixed  with  yeaft,  placed  by  it  as  a 
ftandard. 

The  folution  with  the  yeaft  alone  began  to  ferment  in  12  hours ;  but  the  other,  contain- 
ing the  pot-alh,  fliewed  no  fymptoms  of  fermentation  at  the  end  of  12  days. 

Being  now  in  a  great  meafure  fatisfied,  that  any  fourth  fubftance  combined,  although  in 
fmall  quantity,  with  the  three  which  form  fugar,  would  prevent  fermentation,  we  next  %vifticd 
to  know  if  every  compound,  confifting  of  carbon,  hydrogen,  and  oxygen,  however  differently 
thefe  fubftances  might  be  proportioned,  were  fufceptible  of  its  procefs.  The  fugar  of  milk, 
from  what  has  already  been  obferved,  evidently  confifts  of  thefe  three  fimple  fubftances;  but, 
from  a  number  of  its  fenfible  properties,  and  the  refult  of  its  analyfis  by  heat,  as  well  as 
its  containing  the  radical  of  the  facchola£lic  acid,  it  is  manifeft  that  their  combinations 
and  proportions  muft  be  very  different  from  thofe  in  common  fugar. 

"We  therefore  mixed  a  folution  of  its  faccharine  matter  with  the  ufual  quantity  of  yeaft, 
and  expofed  it  to  a  temperature  ranging  from  65°  to  70°:  in  four  days  fome  degree  of 
fermentation  was  perceptible,  and  in  three  days  more,  became  brilk  :  at  the  end  of  fixteen, 
when  its  procefs  had  apparently  ceafed,  the  liquor  was  examined  :  it  now  had  the  fmell 
of  cyder,  but  rather  more  of  the  flavour  of  apples ;  to  the  tafte  it  was  very  four,  and, 
when  added  to  the  tin£lure  of  litmus,  ftrongly  reddened  it. 

The  acid  thus  procured  either  contained  or  confifted  of  common  vinegar;  for  with  the 
oxyde  of  lead  it  formed  a  fweet  faline  mafs,  compofed  evidently  of  flcnder  prifmatic 
cryftals  which  were  not  deliquefcent.* 

Hence  it  is  manifeft,  that  the  fugar  of  milk  is  at  leaft  in  fome  degree  fufceptible  of 
the  vinous  fermentation. 

Having  obferved,  in  our  attempts  to  convert  gum  into  £iigar,  that  it  feemed  to  run  eafily 
intp  the  acid  ftatc,  we  were  anxious  to  know  if  any  thing  like  fermentation  preceded  this 

■*  See  Scheele's  Efiays,  page  174. 

ftate, 


General  Refults  concerning  Sugar,  Mucilage,  i^fc,  4,1 1 

ftate,  or  if  it  was  pofTible  to  convert  it  into  an  acid,  by  mere  expofure  to  the  air,  without 
the  addition  of  fome  fubftance  containing  much  oxygen,  as  the  nitrous  or  oxygenated  muriatic 
acids.  Accordingly  a  folution  of  gum  arabic,  mixed  with  a  proper  proportion  of  good  yeaft, 
was  introduced  into  an  open  vefle),  and  kept  at  a  temperature  ranging  from  68°  to  75°  for 
twenty-fix  days,  but  during  this  period  nothing  like  fermentation  was  perceived  :  the 
mixture  at  laft  emitted  a  very  peculiar  and  ofFenfive  fmelj :  the  gum,  however,  ftill  retained 
its  natural  tafte,  and  was  not  in  the  le*(l  four.  In  this  cafe  it  fliould  appear,  that  the 
azote,  and  lime,  which  in  the  gum  are  combined  with  carbon,  hydrogen,  and  oxygen, 
prevented  the  vinous  fermentation,  and  confequently  the  formation  of  any  thing  like  vinegar. 

It  has  been  fuppofed,  that  a  deco£lion  of  purely  animal  matter  might  undergo  certain 
fpontaneous  changes,  and  at  laft  become  acid.  In  order  to  determine  this  point,  about 
fixteen  ounces  of  a  ftrong  decoftion  of  beef  were  introduced  into  an  open  veflel,  and  kept 
at  the  temperature  of  about  68°  or  70°.  A  few  days  after,  an  equal  quantity  of  a  fimilar 
decodlion,  mixed  with  an  ounce  of  yeaft,  was  likewife  expofed  in  an  open  veflel  to  air  of 
the  fame  temperature. 

At  the  end  of  five  days,  the  deco£lion,' without  any  mixture,  began  to  fliew  evident 
marks  of  putrefadlioj^,  but  did  not  in  the  Icaft  tafte  acid,  nor  had  it  ever  fliewn  any  figns 
of  vinous  fermentation  j  in  two  days  more  it  became  extremely  oiFenfive,  accompanied 
with  the  produ£lion  of  ammonia. 

The  decoQion  with  the  yeaft  did  not  fhew  any  evident  figns  of  putrefaSion  until  the 
feventh  day,  but  there  was  nothing  like  fermentation  perceived  ;  in  two  days  more  it 
became  extremely  putrid  and  offenfive,  and  was  thrown  away. 

Hence  it  fliould  appear,  that  neither  vegetable  nor  animal  mucilages  are,  when  pure,  in 
any  degree  fufceptible  of  the  vinous  fermentation  :  indeed,  thefe  are  fa£l:s  which  have  been 
fo  generally  admitted,  that,  had  not  a  contrary  opinion  been  lately  advanced,  we  flaould 
have  conceived  the  three  laft  experiments  unneceflary. 

The  miftake  has  no  doubt  arifen  from  obferving  the  facility  with  which  a  decoftion  of 
a  mixture  of  animal  and  vegetable  matter  runs  into  the  acid  ftale  :  but  in  this  cafe  the 
animal  fubftance  performs  the  part  of  yeaft  only  ;  and  it  is  in  this  way  that  diabetic  urine  fo 
readily  ferments  fpontaneoufly,  and  becomes  vinegar. 

From  the  preceding  experiments  we  may  draw  the  following  conclufions  : 

ift.  That  fugar  confifts  of  carbon,  hydrogen,  and  oxygen  ;  and  may  be  confidered 
as  a  pure  vegetable  oxyde. 

ad.  That  fugar  of  milk  is  compofed  of  the  fame  principles,  but  contains  more  oxygen 
and  confiderably  kfs  charcoal. 

3d.  That  gum  differs  from  fugar  in  containing,  befides  carbon,  hydrogen,  and 
oxygen,  both  lime  and  azote. 

4th.  That  vegetable  farina  cannot  be  converted  into  faccharine  matter,  without  the  joint 
aftion  of  oxygen  and  water  ;  the  firft  of  which  appears  to  be  abforbed,  and  the  lait 
decompofed,  during  this  procefs. 

5th.  That  when  fugar  is  deprived  of  its  oxygen,  or  combined  with  other  fubftances> 
it  lofes  its  charafleriftic  properties,  and  is  no  longer  fufceptible  of  the  vinous  fermentation. 

6th.  That  neither  vegetable  nor  animal  mucilages,  in  their  pure  ftate,  are  fufceptible  of 
this  procefs. 

VIL  Or* 


^xt  M^mufa&vyf  of  Hirn.-^Metallk  Suhjlitutt. 

VJI. 

On  the  Art  of  covering  Wire  Cloth  with  a  tr an/parent  Varnijh,  as  a  Suhjlitute  for  Horn  ;  and  on 
other  ObjeSls  of  public  Utility.  By  JlzXIsRocHON^  of  the  National  Infitute  of  France,  b'f.* 


I 


N  the  progrefs  of  the  prefent  war,  the  marine  flore-houfes  of  France  were  totally  with- 
out the  efleiitial  article  of  horns  for  lanthorns.  It  was  impoffible  to  fubftitute  glafs  in  the 
place  of  this  article,  on  account  of  its  brittlenefs,  and  the  obvious  danger  which  might  refult 
from  that  quality.  In  this  fituation  of  diftrefs,  the  agents  of  the  French  government  con- 
fultcd  Citizen  Rochon,  and  directed  him  to  make  every  experiment  he  could  think  of  to  dif- 
cover  a  proper  fubftitute.  His  attention  was  firft  diredled  to  a  memoir  of  the  celebrated  Poivre 
on  the  fabrication  of  lanthorns  of  horn  by  the  Chinefe.  It  is  known  that  this  induftrious 
nation  prefer  horn  to  glafs  on  account  of  its  cheapnefs  and  toughnefs,  and  that  they  poflefs 
the  art  of  welding  this  fubftance  together  with  fo  much  delicacy,  that  they  make  lanthorns 
of  two  feet  diameter  of  aftonifliing  tranfparency,  and  to  all  appearance  of  one  fingle  piece- 
It  is  alfo  known  that  the  Chinefe  ufe  the  horns  of  goats  and  (heep  only,  which  they  foften  and 
fplit  into  lamina:  by  procefles  fuppofed  to  be  unknown  in  Europe  ;  or,  perhap  ,  by  employ- 
ing a  proportion  of  human  labour  and  patience  for  that  purpofc  which  the  European  de- 
mand might  be  inadequate  to  repay.  Citizen  Rochon,  who  does  not  appear  to  be  perfedly  ^ 
aware  of  the  degree  of  accuracy  with  which  the  fame  art  of  fplitting  horn  is  prai^ifed  in 
Europe,  propofed,  that  the  horns  of  beeves  fliould  be  fawed  into  laminae,  and  then  fcraped 
and  poliflied  ;  or,  to  which  he  gives  the  preference,  that  they  fhould  be  laminated  in  boil- 
ing water. 

While  this  aftive  philofopher  was  employed  at  Breft  in  eftablilhing  a  manufadlory  for 
laminating  the  horns  of  beeves,  which  he  purpofed  to  reduce  into  the  ftate  of  a  pafte  by 
means  of  pure  alkali  in  the  digcfler  of  Papin,  it  occurred  to  him,  that  he  might  fupply 
the  prefling  wants  of  the  navy  by  another  expedient,  whichtconfifted  in  the  application  of 
a  coating  of  glue  upon  wire  cloth. 

In  this  procefs,  he  at  firft  tinned  the  Iron  wires  of  the  fieve  cloth  he  made  ufe  of,  but 
afterwards  found  it  more  convenient,  in  every  refpe£l,  to  give  it  a  flight  coating  of  oil 
paint  to  preferve  it  from  ruft.  The  glue  he  made  ufe  of  was  afforded  by  boiling  the  clip- 
pings of  parchment  with  the  air-bladders  and  membranes  of  fea-fifh  ;  materials  which  he 
ufed,  not  from  any  notion  that  they  were  preferable  to  ifinglafs,  but  becaufe  they  were  the 
cheapeft  he  could  procure.  He  added  the  juice  of  garlick  and  cyder  to  his  compofition,  in 
proportions  which,  I  fuppofe,  he  did  not  meafure,  but  which  he  found  to  communicate 
great  tenacity  and  fomewhat  more  of  tranfparence  than  it  would  have  poflefTed  without 
them.  Into  this  tranfparent  and  very  pure  glue  or  fize  he  plunged  his  wire  cloth,  Mhich 
came  out  with  its  interftices  filled  with  the  compound.  It  is  requifite  that  the  fize  (hould 
pofiefs  a  determinate  heat  and  confiftence,  concerning  which,  experience  alone  muft  guide 
the  operator. 

•  Extrafted  from  a  memoir  read  to  the  National  Inftitute  of  France  the  lift  Ventcfe,  in  the  year  VI. 
(March  nth,  1798),  and  infcrted  in  the  Journal  de  Phyfique  for  April  179S.  The  memoir  contains  various 
political  and  economical  oblervations  more  particularly  applicable  to  France,  with  general  obfervations,  which  I 
have  not  thought  it  neccflary  either  to  tranfcribe  or  abridge  ;  neither  have  I  been  folicitous  to  take  the  very 
■wards  of  my  author  in  the  parts  I  have  abftraftcd.    N. 

Whea 


TTire  Qoth  prepared  for  Lanthorns  and  other  U/es.  41  j 

When  this  prepared  wire  cloth  is  fixed  in  the  lanthorn,  it  muft  be  defended  from  moifture 
by  a  coating  of  pure  drying  linfeed  oil ;  but  even  in  this  ftate  it  is  not  fit  to  be  cx- 
pofed  to  the  weather.  The  eafc  with  which  thefe  lanthorns  are  repaired  in  cafe  of  acci- 
■dent,  by  a  flight  coating  of  glue,  is  pointed  out  as  a  great  advantage  by  the  inventor,  who 
likewife  informs  us  that  they  were  ufed  in  the  expedition  to  Ireland  as  fignal  lanthorns, 
though  contrary  to  his  wiflies.  For  this  ufe  he  recommends  the  large  plates  of  mica, 
which  were  then  imported  from  Bolton.  With  the  latter  fubftance,  enclofed  between  two 
:pieces  of  very  open  wire  cloth,  he  made  certain  fquares,  26  inches  in  length  and  18  in 
width,  for  the  light-houfe  at  Ufhant,  which  had  been  damaged  by  a  flock  of  wild  ducks, 
•that  flew  through  the  windows  and  dafhed  out  the  lights. 

Citizen  Rochon  affirms,  that  lanthorns  of  wire  cloth,  prepared  in  his  method,  are  much 
cheaper  than  thofe  made  of  tin  and  horn ;  that  they  are  very  cheaply  repaired,  and  afford  a 
llronger  light. 

He  applied  coarfe  iron  wire  cloth  to  another  ufe,  which,  he  thinks,  may  be  worth  attention 
in  future.  He  made  the  roof  of  one  of  his  workfliops  of  this  wire-cloth  in  order  to  avoid 
the  danger  of  fire,  and  covered  it  with  a  flight  coating  of  plaifter.  He  thinks  that  a  com- 
pofition  of  lime  and  pounded  fcales  of  iron  would  have  been  preferable.  This  coating 
ought  not  to  be  thicker  than  a  flate  ;  and  he  recommends  that  it  (hould  be  penetrated  with 
boiling  whale  oil,  and  painted  with  tar  and  ochre.  Such  a  roof  would  afford  no  hold  for 
the  wind,  and  might,  as  he  apprehends,  be  of  confiderablc  ufe  to  defend  buildings  and 
Iheds  which  require  particular  defence  againft  fire. 

In  the  courfe  of  experiments  made  for  the  difcovery  of  a  varnifh  proper  to  defend 
his  new  lanthorns  from  moifture.  Citizen  Rochon  did  not  employ  refins  or  copal,  which 
are  always  fomewhat  friable,  but  a  perfe<n;  folution  of  elaftic  gum  in  drying  linfeed 
oil.  This  varnifli  or  unguent  having  fixed  the  attention  of  Genouin,  that  learned  chemifl 
demanded  whether  it  might  not  be  praiSlicable  to  ufe  it  in  making  bougies  and  other 
medical  inftruments,  which  were  alfo  at  that  time  very  much  wanted.  From  this  fug- 
g^ftion,  Rochon  employed  tlie  Englifli  machine  for  weaving  whips  to  make  the  morecon- 
fiftent  part  of  the  inftrument.  He  plunged  this  woven  piece  in  a  mixture  of  melted  wax  with 
-a  little  ochre,  then  drew  it  through  a  wire  plate  to  take  off  the  fuperfluous  wax,  and  render 
it  perfedlly  fmooth }  after  which  he  applied  the  varnilh  of  elaftic  gum,  which  completed 
the  inftrument. 

Sartori,  ornamental  painter  at  Breft,  pointed  out  to  our  operator  that  fi(h  glue  is  pre- 
ferable to  parchment  fizc  upon  open  wire  cloth,  becaufe  it  is  more  tranfparent  and  ftronger. 


VIII. 

On  tie  ProduElion  of  Nitric  Jcid  by  the  ContaB  of  Oxygen  very  much  heated  and  the  Air  of  the 

Atmofphere*. 

Jl  K  U  L,  a  celebrated  artift  at  Geneva,  having  conftru6led  and  improved  the  apparatus  of 
Watt  for  the  produflion  of  the  gafes,  was  employed  in  obtaining  by  means  of  this  apparatus 
the  oxygen  gas  from  the  black  oxide  of  manganefe,  taking  care  not  to  clofe  the  apparatus  till 
the  manganefe  was  red-hot,  in  order  to  permit  the  efcapc  of  the  water  and  carbonic  acid 

*  Communicated  to  Dr.  Delamethtrie  by  J.  L.  Odier.    Journal  de  Phyfique,  iii.  N«w  Series,  p.  4^4.  , 

Vol,.  II.— Dec.  1798.  3H  wEUh 


4t4  ■^^'f  ProduBion  of  Nitrous  Acid:— -Of  the  C^yfo/ke. 

■which  this  oxide  always  contains  in  its  native  ftate.  While  the  gas  was  extricated  in  great 
abundance,  one  of  the  cocks  pf  the  tube  through  which  the  gas  pafled  was  accidentally 
opened,  fo  that  a  portion  of  the  gas,  very  hot  and  pure,  was  emitted  into  the  atmofphere. 
At  the  fame  inftant  all  the  affiftants  were  furprifed  by  a  manifeft  fmell  o£  nitric  acid,  and 
a  flight  fume  was  fccn  to  rife  from  the  place  whence  the  gas  had  iffued. 

Profeffor  Piftet,  who  was  prefent,  firli:  took  notice  of  the  fingularity  and  importance  of 
this  fafl:.  It  appears  to  prove,  that  when  hot  and  very  pure  oxygen  is  brought  into  contaft 
with  the  atmofpheric  air  at  the  ordinary  temperature,  nitric  acid  is  formed  by  the  chemical 
combination  of  the  two-conftituent  pxLnciples  of  that  acid ;  fo  that  by  caufing  pure  and  hot 
oxygen  gas.  on  the  one  hand,  and  qtmofpheric  air  on  the  other,  to  pafs  into  a  glafs  globe 
or  any  other  clofc  veffiil,  a  great  quantity  of  nitric  acid  gas  would  be  obtained,  which  might 
be  condenfed  and  abforbtd  by  water  previoufly  put  into  the  vefiel.  Again,  it  is  known  that 
nianganefe  has  the  property  of  abforbing  the  oxygen  of  the  air,  or  of  water,  when  deprived 
of  ito  original  portion  by  mer.ns  of  fire.  It  might  therefore  be  pra£licable,  by  means  of  a 
determinate  quantity  of  t;he  black  oxide  of  manganefe,  to  obtain  fucceflively  from  the  at- 
mofpheric air  itfelf  an  unlimited  quantity  of  nitric  acid,  which  would  befides  have  the  ad- 
vantage of  being  perfeflly  pure,  if  care  was  taken  to  purify  the  atmofpheric  air  made  ufe  of 
in  the  operation 


* 


w> 


IX. 

Attalyfis  of  the  Chryfollte  of  the  Jewellers,  proving  it  to  be  Phofphate  of  Lime. 
By  Citizen  Vav^ELIN\. 


H  E  N  I  frequently  heard  from  the  mouth  of  Fourcroy,  in  his  leftures  during  the 
laft  ten  years,  and  repeated  in  my  memoir  on  the  new  metal  contained  in  native  red  lead, 
that,  if  the  art  of  the  chemifl  could  be  exercifed  upon  the  objects  of  natural  hiftory 
preferved  in  colleftions,  difcoveries  would  often  be  made  of  much  utility  to  the  advance- 
ment of  that  fcience ;  I  did  not  expeft  that  I  fhould  have  fo  fpeedy  an  opportunity  of 
•evincing  the  truth  of  that  obfervation  to  the  Inftitute. 

Naturalifts  have  hitherto  confidered  the  chryfoJite  as  a  precious  fione  of  the  fecond 
order,  and  all  writers  have  arranged  it  at  the  end  of  thf  gems  properly  fo  called.  Citizea 
Lametherie,  in  his  Manuel  du  Mineralogifte,  placed  it  immediately  after  the  emerald  and 
the  aqua  marine  ;  Citizen  Sage,  in  his  Chemical  Analyfis,  has  ranged  k  with  the  faphir  ; 

*  This  faft  appears  to  d^er.-e  the  notice  which  the  Author  and  tfe  worthy  Genevan  Profeffor  have  be- 
llowed upon  it,  and  is  certainly  entitled  to  farther  invcftigation.  In  order  that  the  fpeculations  at  the  end  of 
the  paper  may  be  admitted  or  refuted,  it  appears  necell'ary  to  determine,  whetlier  the  claftic  t5uid  which  ef- 
eapod  was  pur^  oxygeir,  orwas  contajninated  With  nitric  acid.  Thismiglithavebeen  ^fc^rtaVBcAby  examining 
the  water  over  which  the  gas  was  coUefted.  As.t.he  native.o.xide  of  manganefe  contains  azote,  which,  as  Fourcroy 
informs  us,  is  driven  over,  for  the  moft  part,  before  the  ignition;  and  as  Milner  and  Cavendilh  have  fliewn 
that  nitrous  acid  is  formed  by  the  combination  of  oxygen  andasote  at  a  red  heat)  there  feems  to  be  fome  ground 
for  fufpicion,  that  the  nitrous  acid  in  tlie  cafe  before  us  was  formedby  a  remaining  portion  of  azote  in  the  man- 
ganefe after  the  ignition  took  plgce-^rN; 

f  Read  to  the  firft  clafs  .of  the  National  Inftitute  of  Eiance,  in  Brumaire,iin  the  year  VI.  (Nov.  i797f^ 
It  is  infened  in  the  Annales  de  Chimic,  xxvi,  123.  I  have  added  the  words  in  the  title  exprelfiiig  the  com- 
jonent  parts  of  this  ftone..    N. 


Anal^ts  t)f  the  ChrjfJltt.  '  ,        xxe 

»Hd  Wallerlus  has  plactd  it  between  the  emerald  and  the  garnet.    The  account  of  this 
author  is  copied  in  the  note  below*.  " 

Kirwan  ufes  the  term  chryfolite  to  denote  merely  the  peridot,  which  neverthelefs 
differs  from  it  greatly  in'  the  nature  of  its  principles- 

Achard  of  Berlin  analyfed  a  fpecies  of  chryfolite  in  which  he  affirms  that  he  found 
Clex  0.15  i  alumine  0.64  ;  lime  0.17  ;  iron  o.i. 

But  the  refults  of  this  analyfis  are  fo  diiFerent  from  mine,  that  I  ftrongly  fufpe(3t  he  muft 
have  operated  on  a  different  ftone  from  the  true  chryfolite.  This  fufpicion  is  fo  much 
the  more  probable,  as  the  name  of  chryfolite  has  been  given  to  many  different  ftones, 
particularly  the  peridot,  the  chryfo-beryl,  the  olivine,  and  in  general  all  ftones  which 
have  a  greenlfli  yellov/  colour. 

Citizen  Launoy,  in  a  journey  he  is  at  prefent  performing.in  Spain  to  colle£t  the  objeils 
of  natural  hiftory,  found  in  the  hands  of  a  dealer  a  confiderable  quantity  of  chryfolitcs, 
which  he  fent  to  Paris  ;  and  the  Council  of  Mines  having  purchafed  part  of  them,  dire£led 
nje  to  fubmit  them  to  analyfis. 

It  was  not  long  before  I  difcovered  that  this  fofTil,  which  has  all  the  external  appearances 
of  a  ftone,  is  not  truly  of  that  clafs  ;  but  that,  on  the  contrary,  It  is  a  fait  compofed  of  an 
«cid  and  a  bafe. which  are  both  well  known;  namely,  the  phofphoric  acid  and  lime. 

As  foon  as  I  had  obtained  this  firft  refult  I  enquired  of  Citizen  Hauy,  whether  he  had 
compared  the  maffes  of  chryfolite  with  thofe  of  the  apatite  or  cryftallifed  phofphate  of 
Kme.  He  anfwered,  that  he  had  not,  but  that  he  had  among  his  papers  the  relative  refults  o£ 
the  primitive  forms  of  both,  and  would  immediately  compare  them.  He  found  with 
pleafure  that  they  did  not  differ  in  the  leaft  appreciable  quantity ;  and  this  conclufion  may 
even  be  drawn. from  the  refults  of  which  he  has  given  an  abftradt  in  his  treatife  publiflied  ia 
the  Journal  des  Mines.  Citizen  Hauy,  therefore,  difcovered  by  geometry  what  I  confirmed 
by  chefnical  analyfis  ;  and  this  fatisfaflory  agreement,  between  two  fciences  apparently  fo 
remote  from  each  other,  affords  a  proof  of  the  truth  and  certainty  of  their  refpe£tivc 
principles. 

I  fliall  now  proceed  to  relate  the  experiments  by  means  of  which  I  afcertalned  the  nature 
of  the  principles  of  the  chryfolite,  and  determined  their  proportions. 

Experiment  i.  Two  hundred  parts  of  chryfolite  in  cryftals  being  fubjeded  to  the  aftion 
of  a  ftrong  heat  for  one  hour,  loft  their  yellow  colour  without  undergoing  any  change  of 
form  or  tranfparency.  They  then  rcfembled  rock  cryftal,  and  had  loft  only  one  two- 
hundredth  part  of  their  weight. 

Experiment  2.  One  hundred  parts  of  pulverifed  chryfolite  were  mixed  with  the  fame 
quantity  of  concentrated  fulphuric  acid,  and  about  four  hundred  parts  of  diftilled  watet; 
the  mixture  immediately  became  hot,  and  alfumed  the  confiftence  of  thick  foup.  Nearly 
tlie  fame  quantity  of  water  as  before  was  added,  and  the  whole  was  boiled  for  feveral 
hours  in  a  matrafs  with  a  long  neck.     The  mixture  being  then  diluted  with  much  water 

*  "  Colore  haec  gemma  gramineo  viridl  flavo,  feu  aurantiorum,  omnibus  gemmis  imo  cryftaJlo  montane 
moUior,  chalybc  rafilis,  calcinata  colorum  tranTparcntiam  perdit,  albefcens,  pondcre  ct  parum  diminuitur  j 
ccrtls  circumftantiis  per  fe  liquabilis  in  vitrum  opacum  album  ;  in  eo  etiam  a  reliquis  gemmis  diftincfta,  quod  in ' 
momento  fufionis  eodem  modo  phofphorefcat  ut  terra  aluminaris,  vel  fpathum  gypfofura.  Cum  borace  inftar 
fmaragdi  in  fufionibus  fe  habet,  qu^m  tamen  gravitate  fpecificj  fuperat  in  proportione  ad  aquam  ut  3.600,  vel 
J. 700  :  1. 000.  Figura  dicitur  efic  polygona  feu  quadrangularis ;  occurrit  etijra  filiciformis,  rotundata,  ia 
Bfafvlia." 

3  H  2  was 


4f6  7}3e  Chr^foUte  Jhnm  io  he  ThJ^lait  of  Lwi/, 

was  filtered  j  and  the  folid  matter  being  collefted,  waflied,  and  ignited  in  i  filver  crucible, 
weighed  ii6  parts.  This  matter,  fubjeded  to  various  proofs,  exhibited  all  the  charadlers  of 
ftilphate  of  lime. 

The  filtered  liquor  was  evaporated  to  drynefs  in  order  to  expel  the  fulphuric  acid.  The 
rfefidue  was  du£lile,  and  might  be  drawn  out  into  threads  as  long  as  it  preferved  its  heat ; 
but  it  hardened  by  cooling  like  a  kind  of  glafs  flightly  opaque  ;  it  weighed  46  parts.  Thefe 
forty- fix  parts,  dilTolved  in  water  and  mixed  with  carbonate  of  ammoniac,  formed  an 
abundant  precipitate  which  became  ftill  more  abundant  by  heat.  This  precipitate  feparaC- 
ed  by  the  filter,  wafhed,  and  ignited  in  a  filver  crucible,  weighed  11  parts.  It  was  phof- 
phate  of  lime  not  decompofed. 

The  fluid  thus  cleared  of  the  phofphate  of  lime  was  evaporated  to  the  confidence  of  3 
fyrup.  At  the  expiration  of  feveral  days  it  afforded  cryftals  in  the  form  of  a  four-fided 
prifm  terminating  in  quadrangular  pyramids,  whofe  fides  correfponded  with  thofe  of  the 
prifm,  and  of  a  penetrating  urinous  tafte.  Heat  decompofed  this  fait,  ammoniac  was 
driven  oiF,  and  the  acid  remained  in  the  fi;ate  of  a  perfe£tly  tranfparent  glafs.  The  glafs> 
mixed  with  the  powder  of  charcoal  and  ftrongly  heated  in  a  retort,  very  fpeedily  afforded 
phofphorus. 

It  cannot  be  doubted,  therefore,  but  that  this  pretended  ftone  is  a  combination  of  time 
and  phofphoric  acid;  a  true  native  phofphate  of  lime  in  crydals.  Ncverthelefs,  though  I 
am  convinced  by  experience  of  the  accuracy  of  the  refult  I  have  announced,  I  was  defirou^ 
of  making  fome  other  experiments  in  order  that  there  might  not  be  the  flighteft  doubt 
upon  the  fubje£l. 

Experiment  3.  One  hundred  parts  of  the  fame  fubftance  in  powder  were  digefted  in 
muriatic  acid  diluted  with  two  or  three  parts  of  water.  The  folution  took  place  fpeedily 
*rithout  the  lead  eifervefcence  ;  it  was  clear  and  colourlefs. 

This  foluiion,  evaporated  nearly  to  drynefs  in  order  to  difpel  the  excefs  of  muriatic  acid> 
was  again  diluted  with  water,  and  mixed  with  a  folution  of  oxalic  acid,  till  the  precipitate 
which  immediately  followed  was  no  longer  produced.  The  filtered  liquor  left  upon  the- 
paper  a  precipitate,  which  after  walhing  and  drying  weighed  118  parts.  Thefe  1 18  parts  of 
precipitate,  ftrongly  calcined  in  a  crucible,  aflumed  at  firft  a  black  colour  arifing  from  the 
coal  of  the  oxalic  acid  decompofed  by  the  fire.  This  coal  being  burned  off,  there  remained 
54,2s  parts  of  a  white  puiverulent  fubftance,  which  was  acrid,  foluble  in  water,  turned 
vegetable  blue  colours  to  a  green,  and,  in  a  word,  prefented  all  the  charadcrs  of  pure  lime. 
The  fluid  from  which  the  oxalate  of  lime  had  been  feparated  was  evaporated  to  drynefs, 
and  alTumed  a  black  colour  on  account  of  an  excefs  of  oxalic  acid  which  the  heat  had. 
decompofed. 

When  the  whole  of  this  laft  acid  appeared  to  have  been  entirely  converted  into  carbonj^ 
the  refidue  was  difTolved  in  water,  and  the  folution  filtered  in  order  to  feparate  the  carbon. 
The  fluid  part,  faturated  with  carbonate  of  ammoniac,  let  fall  a  few  light  flocks  of  phofphate 
of  lime  which  weighed  one  part.  This  fluid,  fubjeded  to  evaporation,  afforded  a  fait 
perfedly  refembling  that  of  the  former  experiment.  It  was  decompofed  by  lime  water, 
and  was  fufed  with  the  blow-pipe,  with  inflation,  and  emitted  a  fmell  of  ammoniac  and' 
a  yellow  greenifli  light.     The  refi^ue  was  a  tranfparent  glafs. 

Since,  therefore,  this  experiment  perfedly  agrees  with  the  former,  not  only  with  regard 
to  the  nature  of  the  principles^of  the  chryfolite,  but  alfo  the  proportions,  as  will  imme- 
diately 


StiigiJaf  Jppeafanet  if  the  Ceajt  of  France  by  RefraB'ton.  'jpf  '^ 

ffiateTy  be  fhewn  ;  it  would  be  ufelefs  to  add  to  the  number  of  experiments,  which  would  ' 
convey  no  otlicr  information  than  is  already  known  concerning  the  phofphate  of  lime. 

In  order  to  eftabllfh  the  proportions  of  phofphoric  acid  and  lime  in  the  chryfolite,  It 
muft  be  recolIe£ted,  i.  that  loo  parts  of  this  fubftance  aiFordfd  in  the  fecond  experiment 
Il6  parts  of  calcined  fulphate  of  lime,  which,  according  to  Bergman,  contained  48,84. 
of  pure  lime :  2.  that  there  remained  1 1  parts  of  phofphate  of  lime  not  decompofed,, 
which  were  capable  of  forming  14,33  °^  fulphate  of  lime,  which  added  to  the  116  give 
J3C'>33-  Now  if  116  contain  48,84  of  Hme,  it  is  evident  that  130,33  muft  contain  53,32. 
According  to  this  experiment,  therefore,  100  parts  of  chryfolite  contain  53,32  of  lime  ;  and 
fubtradting  this  from  the  100,  there  will  remain  for  the  phofphoric  acid  46,68.  In  the 
third  experiment  it  is  alfo  feen,  that  100  parts  of  chryfolite,  diflblved  in  the  muriatic 
acid,  afforded  by  the  oxalic  acid  1 1 8  parts  of  oxalate  of  lime  ;  and  that  thefe  1 1  8  parts  left 
after  calcination  54,28  parts  of  pure  hme,  which  fubtradted  from  100,  give  45,72  for  the 
phofphoric  acid. 

We  fee,  therefore,  that  the  refults  of  thefe  two  experiments  do  not  diflfer  fo  much  as 
one  hundredth  part  from  each  other,  and  that  they  perfeftly  agree  with  the  component 
parts  obtained  by  Klaproth  in  his  analyfis  of  the  apatite,  from  which  he  obtained  55,  parts 
©f  lime  and  45  of  phofphoric  acid. 

X. 

Account  of  a  fingular   Injiance  af  Atmofpherical  RefraSlioii.     In  a   Letter  from    JVlLLIAM 

Latham,  Ef^.  F.R.S.  andJ.S.  tn  the  Rev.  H.  Whitfield,  D.D.  F.R.S,  and  A.S* 


O 


Dear  Sir,  Haftings,  Auguft  i,  1797. 


N  Wednefday  laft,  July  26,  about  five  o'clock  in  the  afternoon,  whilft  I  was  fitting  in 

my  dining-room  at  this  place,  which  is  fituated  upon  the  parade  clofe  to  the  fea-fliore, 

nearly  fronting  the  fouth,  my  attention  was  excited  by  a  great  number  of  people  running 

down  to  the  fea-fide.    Upon  enquiring  the  reafon,  I  was  informed  that  the  coaft  of  France 

was  plainly  to  be  diflinguifiied  with  the  naked  eye.    1  immediately  went  down  to  the  fhore„ 

and  was  furprifed  to  find  that,  even  without  the  afiiflance  of  a.  telefcope,  I  could  very  plainly 

fee  the  cliffs  oi^the  oppofite  coaft;  which,  at  the  nenreft  part,  are  between  forty  and  fifty  miles 

diftant,  and  are  not  to  be  difcerned„  from  that  low  fituation,  by  the  aid  of  the  beft  glafles. 

They  appeared  to  be  only  a  few  miles  off,  and  feemed  to  extend  for  fome  leagues  along  the- 

coaft.     I  purfued  my  walk  along  the  fhore  to  the  eaftward,  clofe  to  the  water's  edge,  con- 

verfing  with  the  failors  and  fiftientien  upon  the  fubjeft.     They,  at  firft,  could  not  be  per- 

fuaded  of  the  reality  of  the  appearance  ;  but  they  foon  became  fo  thoroughly  convinced,  by 

tlie  cliffs  gradually  appearing  more  elevated,  and  approaching  nearer,  as  it  were,  that  they 

pointed  out,  and  named  to  me,  the  different  places  they  had  been  accuftomed  to  vifit ;  fuch 

as,  the  Bay,  the  Old  Head  or  Man,  the  Windmill,  &c.  at  Boulogne  ;  St.  Vallery,  and  other 

places  on  the  coaft  of  Picardy  ;  which  they  afterwards  confirmed,  when  they  viewed  them. 

through  their  telefcopes.     Their  obfervations  were,  that  the  places  appeared  as  near,  as  if. 

tlaey  were  failing,  at  a  fmall  diftance,  into  the  harbours. 

*  Philof.  Tr'Hf-  '798,  page  35;. 

Having; 


4l8  Swgtilar  Injtaiice  of  UrreJIrial  RefrnSilotii 

Having  indulged  my  curiofity  upon  the  fliore  for  near  an  hour,  during  which  the  cliffs 
appeared  to  be  at  fome  times  more  bright  and  near,  at  others  more  faint  and  at  a  greater 
(dillance,  but  never  out  of  fight,  I  went  upon  tlie  eaftern  cliff  or  hill,  which  is  of  a  very 
confiderable  height,  when  a  moft  beautiful  fcenc  piefented  itfelf  to  my  view  ;  for  I  could 
at  once  fee  Dengenefs,  Dover  cliffs,  and  the  French  coafl,  all  along  from  Calais,  Bou- 
logne, &c.  to  St.  Vallery;  and,  as  fome  of  the  fifhermen  afErmed,  as  far  to  the  weilward 
even  as  Dieppe.  By  the  telefcope,  the  French  fifhing-boats  were  plainly  to  be  feen  at  anchor ; 
?tnd  the  different  colours  of  the  land  upon  the  heights,  together  with  the  buildings,  were 
perfeftly  difcernible.  This  curious  phenomenon  continued  in  the  higheft  fplendour  till 
paR  eight  o'clock  (although  a  black  cloud  totally  obfcured  the  face  of  the  fun  for  fome 
time),  when  it  gradually  vanifhed. 

Now,  Sir,  as  I  was  afTured,  from  every  enquiry  I  could  pofTibly  make,  that  fo  remarkable 
an  inftance  of  atmofpherical  refraction  had  never  been  witneffed  by  the  oldefl  inhabitant 
of  Haftings,  nor  by  any  of  the  numerous  vifitors  (it  happening  to  be  the  day  of  the  great 
annual  fair,  called  Rock  fair,  which  always  attracSts  multitudes  from  the  neighbouring  places}, 
I  thought  an  account  of  it,  however  trifling,  would  be  gratifying  to  you. 

I  fhould  obferve,  the  day  was  extremely  hot,  as  you  will  perceive  by  the  fubjoined  rough 
journal  of  a  fmall  thermometer,  which  was  kept  in  the  dining-room  above  mentioned.  I  had 
no  barometer  with  me,  but  fuppofe  the  mercury  mufl  have  been  high,  as  that  and  the  three 
preceding  days  were  remarkably  fine  and  clear.  To  the  befl  of  my  recolledlion,  it  was  high 
water  at  Haflings  about  two  o'clock  P.M.  Not  a  breath  of  wind  was  flirting  the  whole 
■of  the  day ;  but  the  fmall  pennons  at  the  mafl-heads  of  the  fifhing-boats  in  the  harbour 
were,  in  the  morning,  at  all  points  of  the  compafs- 

I  am,  &c. 

WILLIAM  LATHAM. 

P.  S.  I  forgot  to  mention,  that  I  was  a  few  days  afterwards  at  Wlnchelfea,  and  at  fc- 
veral  places  along  the  coafl: ;  where  I  was  informed  the  above  phenomenon  had  been  equally 
vifible.  I  fhould  alfo  have  obferved,  that  when  I  was  upon  the  eaftern  hill,  the  cape  of 
land  called  Dengenefs,  which  extends  nearly  two  miles  into  the  fea,  and  is  about  fixteen 
miles  diftant  from  Haftings,  in  a  right  line,  appeared  as  if  quite  clofe  to  it ;  as  did  the  fiili- 
ing-boats,  and  other  vefTels,  which  were  failing  between  the  two  places :  they  were  like- 
wife  magnified  to  a  great  degree*. 

*  On  this  interefting  fubjcft  fee  Mr.  Huddart's  Obfervations  on  Horizontal  Refraftions,  Philof.  Journal,  I. 
145.  Ellicor,  on  the  Phenomenon  of  Looming,  I.  151.  The  Fata  Morgann,  or  Appearance  of  Figures  in 
the  Sea  and  Air,  before  Reggio,  defcribed,  I.  215.  Mudge,  in  the  Philof.  Tranf.  1795,  P-  5^''>  5^7- 
Smeaton's  Account  of  Eddyftone  Light-Houfe,  p.  191.  Button's  Diftionary,  II.  352.  Thefe  appearances 
arc  much  more  frequent  and  general  than  has  ufually  been  fuppofcd.  I  have  been  credibly  informed,  that 
the  Fata  Morgana  has  been  feen  from  Broad  Stairs,  in  Kent ;  and  that  the  elevation  and  inverfion  of  rer- 
reftrial  objefts  is  commonly  or  frequently  obfervabic  (in  fummcr,  I  fuppofe),  through  a  telefcope,  over  level 
ground,  if  tlie  eye  of  the  obferver  be  not  much  elevated.  In  the  curious  inftance  related  above  by  Mr.  La- 
tham, it  dees  not'feem  probable  that  the  French  coaft  was  enlarged,  but  that  it  was  only  elevated  by  the  re- 
fradlion.  At  all  events,  the  objefts  could  fcarcely  have  fufTered  any  alteration  of  the  horizontal  angles  or 
Jiearings.     N. 

STATE 


r  419  1 

STATE  of  the  THERMOMETER  at  HjiSTlNGSy  during  the  Month  «/ JULY  1797. 


1797. 

Therm. 

Time. 

Wind. 

Weather. 

July  I. 

64 

10  A.M. 

SW 

Windy.  Fair. 

2. 

64 

10 

•  SW 

Windy.  Fair. 

3- 

62 

10 

SW 

Rain.  Windy. 

4- 

62 

10 

SW 

Fair.  Windy. 

5- 

61 

10 

SW 

Rain.  Windy. 

6. 

60 

10 

SW 

Rain.   Windy. 

7- 

61 

10 

W 

Rain.  Windy. 

8. 

62 

10 

NW 

Fine. 

66 

5  P.  M. 

NW 

Fine. 

-  g. 

66 

10  A.  M. 

SW 

Fine. 

10. 

67 

10 

N  after w.  SW 

Fine. 

II. 

65 

10 

SW 

Foggy  all  day. 

12. 

63 

10 

SW 

Fine.                  ■• 

13- 

72 

10 

SW 

Fine. 

I4v 

76 

10 

w 

Fine. 

68 

12 

w 

Fine. 

IS- 

72 

10 

w 

Fine. 

16. 

72 

10 

N 

Fine. 

78 

7  P.M. 

E 

Storm  of  Wind.  Lightning. 

17- 

73 

10  A.  M. 

w 

Fine. 

18. 

70 

""^ 

w 

Fine.  Showers  in  the  Night. 

19. 

67 

1° 

wsw 

Fine.  Windj'. 

ao. 

67: 

10 

SW 

Rain.  Windy. 

21. 

65 

10 

SW 

Fine.  Windy. 

22. 

61 

10 

S 

Rain. 

23- 

65 

10 

S 

Fme. 

24. 

66 

10 

s 

Fine. 

25- 

66 

10 

SW 

Fine. 

26. 

68 

10 

SW 

Fine.  Dead  calm  all  day. 

76 

S  P.M. 

SW 

Fine. 

27. 

72 

10  A.M. 

SW 

Fine. 

28. 

70 

10 

S 

Fine. 

29. 

72 

10 

E 

Fine. 

30- 

70 

10 

SW 

Rain. 

31- 

69 

10 

s 

Fine.  Windy. 

^li  Mxcitdt'ion  of  EkSirkttj  hy  various  No/i-conduBfin,. 

XI. 

^»  Account  of  EleSlrical  Machines  of  cot  ft  der able  Power,  in  luhich  Silk  is  ufed  inflead  of 


E: 


Glafs,     W.  N. 


(LECTRICITY  has  been,  in  moft  praftical  cafes,  excited  or  coUefted  by  the 
fri£lion  of  various  fubftances  againft  each  other.  In  this  procefs,  which  has  not  yet  been 
explained  by  reference  to  fimpler  phenomena,  it  is  'a  known  condition,  that  one  at  leaft  of 
the  fubftances  rubbed  muft  be  a  non-condu£tor.  Refin,  lack,  filk,  baked  wood,  and 
above  all  glafs,  are  the  bodies  which  have  hitherto  been  ufed.  The  durability  and 
unchangeable  nature  of  glafs*,  and  its  being  very  little  if  at  all  affefled  by  the  atmofpherical 
variations,  are  undoubtedly  the  caufes  why  it  has  obtained  the  preference.  Its  brittlenefs, 
and  the  great  cxpence  of  large  plates  or  cylinders,  are  certainly  among  thofe  reafons  why 
phiiofophical  operators  fliould  be  defirous  of  a  fubflitute  of  lefs  coft  and  danger. 

Dr.  Ingenhoufz,  the  inventor  of  the  plate  machine,  made  a  variety  of  experiments  for 
this  purpofe.  Pafteboard  thoroughly  dried  and  heated,  and  then  foaked  and  varniflied. 
with  a  folution  of  amber  in  linfeed  oil,  formed  plates  which  were  ftrongly  eleftrified 
when  rubbed  with  a  cat's  flcin  or  hare's  fkin.  He  tried  baked  wood  boiled  in  linfeed  oil, 
but  with  lefs  fuccefs.  A  cylinder  of  itrong  Clk  velvet,  formed  by  ftrctching  that  fubftance 
upon  two  circular  wooden  diflcg,  was  found  to  afford  confiderable  electrical  force  when 
caufed  to  revolve  againft  a  cufhion  covered  with  hare's  fkinf .  And  laftly,  the  fame 
philofcpher  contrived  a  portable  apparatus  for  charging  a  jar  by  means  of  a  rarniftied  filk 
ribband,  expofed  to  the  fri£lion  of  a  rubber  attached  to  the  external  coating,  while  the 
oppofite  eledtricity  of  the  filk  was  taken  off  by  a  metallic  part  communicating  with  the 
infidej. 

It  was  at  the  beginning  of  1784  that  M.  "Walckiers  de  St.  Amand  undertook  to 
conftru£l  a  machine,  in  which  a  piece  of  filk  was  made  to  revolve  inceflantly,  and  pafg 
between  two  pair  of  rubbers.  He  made  one  of  fmall  dimenfions,  and  afterwards  a  larger 
in  which  the  filk  was  twenty-five  feet  in  length,  and  five  feet  broad.  In  the  following 
year  a  machine  of  the  fame  kind  was  conftruded  by  M.  Rouland,  profeflbr  and  lefturer 
in  natural  philofophy  in  the  univerfity  of  Paris  f  As  no  accounts  of  either  of  thefe  have 
been  publifhed  in  this  country  H,  and  the  advantages  and  efFedls  defcribed  by  the  authors 

appear 

•  Mr.  C.  Cuypers  of  Dclft  aflirms  that  glafs  becomes  harder,  and  fitter  for  eleftrical  purpofes,  by  long 
expofure  to  the  wann  air  of  a  room  ;  and  Mr.  Birch,  of  EiTex-ftrect,  in  a  very  extenfive  cleftrical  praflice, 
found  that  glafs  cylinders  lo'e  their  power  by  long  ufc,  fo  as  to  become  of  no  value  ;  but  he  afcribes  this  change 
to  the  ufe  of  the  aurum  mufivum  on  the  cufliion. 

f  Bakerian  Lefture,  Phil.  Tranf.  1779. 

+  Nouvelles  Experiences,  &c.  fur  la  Phyfique,  par  J.  Ingenhoufz,  F.R.S.  &c.     Paris,  17E5. 

^  Defcription  des  Machines  eleftriques  a  tafl'ctas,  par  M.  Rouland,  &c.  Amfterdam  and  Paris  17S5,  oflavo, 
3  5  pages,  with  one  plate,  of  wliich  PI.  XVllI.  is  a  copy.  — The  Report  of  the  Parifian  Academyon  the  Machine 
of  M.  Walckiers,  dated  25th  March  1784,  was  fcparately  printed  in  29  pages  OcStavo,  with  a  coloiired  plate. 
The  Report  is  copied  in  M.  Rouland's  pamphlet. 

IJ  Some  time  after  the  conftruftioji  of  thefc  machines,  Mr.  Edward  Nairne,  of  Cornhill,  whofe  rcfearches 
in  this  and  other  praftical  departments  of  fciencc  are  well  known,  received  an  order  to  conftruft  one  of  the  fame 
form,  but  found  it  impollibleby  any  adjufbnent  to  prevent  the  filk  from  running  totally  to  one  or  the  other  end 

of 


Ele^rlcai  Muchlfle  sperat'tiig  h^^the  Frisian  ofSifk,  4*t 

«ppc3r  to  be  corifiderable,  I  have  thought  it  of  advantage  to  Ihrert  the  defcription  of  the 
latter  in  this  plafe. 

A,  B,  n.  XVlII.  is  a  wooden  table  four  feet  and  a  half  long,  two  feet  nine  inches  wide, 
and  fomewhat  more  than  an  inch  and  a  half  thick  :  its  feet  are  1 8  inches  long.  Upon 
this  table  are  faftened  by  ftrong  wooden  fcrews,  a  h  c  d,  two  crofs  pieces,  each  nine 
inches  broad,  which  carry  the  uprights  C,  D,  E,  F,  which  laft  are  27  inches  in  height. 
At  about  two-thirds  or  more  of  the  height  of  thefe  uprights,  there  are  cut  notches  of  an 
inch  fquare  each,  in  which  tlie  axes  of  the  two  cylinders  G  and  H  turn  freely.  Thefe 
axes  are  parallel  to  the  table  and  to  each  other,  and  are  kept  in  their  place  by  clamps  of 
wood  fcrewed  over  them.  The  cylinders  G  and  H  are  formed  of  light  wood  glued 
together,  and  covered  at  the  ends  by  a  circular  piece,  whofe  rounded  edges  arife  half  an 
inch  above  the  furface  of  the  cylinders  themfelves.  Their  diameter  is  eight  inches ;  the 
axes  are  of  box  wood,  and  are  lefs  than  an  inch  in  diameter,  having  a  fhoulder  which 
prevents  the  ends  of  the  cylinders  from  touching  the  uprights  when  turned  round  ;  and 
laftly,  the  cylinders  are  covered  with  ferge. 

The  handle  is  copper,  its  radius  being  fix  inches  long. 

K,  L,  is  a  piece  of  tafFety  covered  witji  oily  and  refinous  matter,  of  the  fame  kind  as  is 
ufed  in  France  in  the  conftruflion  of  air-balloons,  which,  M.  Rouland  fays,  renders  the 
Clk  very  ele£l;rical :  the  breadth  of  the  filk  is  nearly  one  inch  lefs  than  the  length  of  the 
cylinders,  and  it  is  wrapped  round  them  with  its  ends  fewed  together. 

The  whole  breadth  of  the  filk  is  taken  hold  of  or  pinched  between  two  flattened  tin  tubes 
oppolite  each  other  at  M,  and  two  of  the  fame  kind  at  N  :  thefe  are  the  rubbers,  and  may 
be  made  to  prefs  againft  each  other,  more  or  lefs  ftrongly,  by  means  of  fcrews.  They  arc 
retained  by  firings  of  filk  faftened  to  the  four  uprights  of  the  machine,  v  v  are  two  brafs 
chains  hooked  upon  the  rubbers,  and  communicating  with  the  earth  ;  op  and  q  r  are  four 
pieces  of  tafFety,  prepared  in  the  fame  manner  as  the  principal  piece,  fewed  in  the  dire£lion 
of  their  length  to  the  rubbers,  and  faftened  to  each  other  by  their  correfponding  corner* 
by  means  of  threads  of  filk.     The  metallic  tubes  or  rubbers  are  covered  with  cat's  flcin. 

S  reprefents  the  conduftor.  It  is  a  cylinder  of  brafs  thrge  inches  in  diameter,  36 
inches  in  length,  including  the  balls  at  the  end,  whofe  diameters  are  four  inches  :  one  of 
thefe  balls  has  a  ring,  t,  above  it,  which  ferves  to  form  a  communication  between  the 
conduftor  S  and  any  other  condudor. 

The  upper  and  lower  parts  of  this  cylindrical  prime  conduflor  are  armed  with  two 
plates  of  brafs  ^;i,  whofe  length  is  equal  and  correfpondenc  to  the  breadth  of  the  taffety, 
which  is  16  inches,  aiid  132  inches  or  1 1  feet  long  :  the  edges  of  the  plates  are  abctit  half 
an  inch  dlftant  from  the  filk,  and  ferve  inftead  of  the  metallic  points  that  were  ufcd  by 
M.  Walckiets,  but  rejedted  by  M.  Rouland,  becaufe  they  were  apt  to  ftick  into  the 
filk  and  damage  it. 

of  the  cylinders.  The  inventors  have  given  no  inftruftions  to  obviate  this  defeft.  I  have  no  doubt  but  that 
they  made  their  rollers  gradually  largeft  in  the  middle.  1  have  fecn  a  machine  for  folding  woollens,  invented 
and  made  by  Mr.  Rehe,  of  Shoe-lane,  in  which  this  difficulty  was  removed  in  fomc  leading  rollers,  by  making 
them  in  the  form  of  two  very  acute  frnftums  of  cones,  joined  at  the  middle  by  the  larger  bafc. — See  Phil. 
Journal,  I.  13. 

Vol.  IL—Dec.  1798.  3  I  The 


421  EUBi-ica!  Machine  eperailng  hy  the  FriBioti  of  Sm, 

The  conductor  S  Is  fufpended  by  filk  ftrings,  faftened  to  the  uprights  of  the  machine  by 
the  hooks  and  rings  i  i :  its  fituation  is^  parallel  to  the  cylinders  G,  H,  and  equidiftant  from 
each.  The  aflion  of  this  machine  is  as  follows :  The  cylinder  H  is  moved  rapidly  on  its 
'axis  by  means  of  the  handle,  and  the  cylinder  G  moves  of  courfe  in  the  fame  direction  on 
the  two  extremities  of  its  axis,  provided  the  tafFety  K,  L,  be  properly  flretched.  This  ten- 
fion  is  eafily  obtained  ;  becaufe  the  crofs  pieces  to  which  the  uprights  C,  D,  and  E,  F,  are 
fixed,  may  be  moved  nearer  or  further  from  each  other,  and  faftened  by  means  of  the 
fcrews  a  b  and  c  d,  which  pafs  through  holes  cut  in  the  direction  of  the  table. 

The  rotation  of  the  cylinders  neceflarily  producing  a  circulation  of  the  tafFety,  it  muft 
confequently  be  rubbed  in  its  paflage  between  the  tin  tubes  covered  with  cat's  (kin  at  M 
and  N ;  and  by  this  friction  it  obtains  what  is  called  the  negative  eledtricity,  which  is  com- 
municated from  both  parts  of  the  filk  to  the  common  condu£lor  S.  But  it  may  be  made  to 
eleflrify  pofitively,  by  removing  the  rubbers  to  the  middle  of  the  filk,  fo  that  the  prime 
Condu<Sor  may  communicate  with  them  :  or,  if  the  two  cufliions  be  removed  to  half  the 
diflance  between  the  revolving  cylinders  and  the  prime  condu6lor,  pofitive  and  negative 
electricity  may  be  had  at  the  fame  time,  the  rubbers  being  in  a  negative  ftate,  and  the 
prime  conduiStor  in  a  pofitive  ftate. 

The  advantages  of  a  machine  of  this  conftru£tion  beyond  thofe  of  glafs  are  ftated  by  the 
inventor  to  be,  i.  It  is  not  brittle  in  any  part.  2.  Its  excitation  is  more  Itcady,  becaufe  it 
requires  no  amalgam      3.  Its  dimenfions  have  no  limit. 

The  power  of  excitation  in  this  way  appears  to  have  been  very  confiderable.  The  fa£l* 
are  not  related  with  fo  much  detail  as  could  be  wifhed  in  the  Report  of  the  Academy  ;  but 
it  appears  that  the  negative  fparks  from  the  conducSlor  of  Walckiers,  which  was  tive  feet 
long,  were  from  J  5  to  17  inches  in  length,  very  loud  and  denfe,  and  very  painful  to  the 
hand  ;  that  pointed  bodies  emitted  very  fenfible  fparks  to  the  conduftor  ;  and  that  a  battery 
of  50  fquare  feet  was  charged  by  30  turns  of  the  machine,  which  gives  19  feet  of  filk  rub- 
bed to  charge  one  foot  of  glafs*.  In  another  inftance,  however,  it  is  faid,  that  a  fquare 
foot  was  charged  by  one  turn  of  the  machine,  which  anfwered  to  31 J^  fquare  feet  of  filk. 
It  is  not  faid  whether  the  labour  of  turning  was  confiderable  or  not. 

M.  Rouland  made  feveral  trials  to  fubftitute  plain  filk  inftead  of  that  which  was  var- 
nlflied  ;  and  he  a!fo  tried  woollens  and  mixed  cloth  containing  goat's  hair;  but  none  of 
thefe  anfwered  to  his  fatisfa£lion. 

XII. 

Experimental  Refearches  concerning  the  Principle  of  the  lateral  Communication  of  Motion  in  Fluids,, 
applied  to  the  Explanati$n  of  various  Hydraulic  Phenomena,  By  Citizen  J.  B.  VenTURI^ 
Profeffor  of  Experimental  Philofophy  at  Medena,  Member  of  the  Italian  Society,  of  the  InJU-^ 
tUte  of  Bologna,  the  Agrarian  Society  of  Turin,  isfc. 

(Continued  froTn  page  276,  vol,  ii.) 

TPropofttion  VI. 
H  E  expence  of  fluid  is  lefs  through  cylindrical  tubes  than  through  conical  tubes,, 
which  diverge  from  the  commencement  of  the  contrafted  vein,  and  have  the  fame  external 

diameter. 

•  See  Philof.  Joura,  I.  87. 


On  the  lattral  Communtcatton  of  Mot'mi  In  Fluids,  '  423 

The  general  theory  is  the  fame  for  both  thefe  forms  of  tubes ;  but  the  lofs  of  living 
force  is  greater  in  the  cylinder,  and  the  efFeft  of  the  communication  of  motion  in  thefc 
tubes  cannot  approach  its  maximum  as  in  the  cone.  Let  the  tube  A  C  N  M,  fig.  5.  PI.  VIII. 
of  the  prefent  volume,  have  the  form  of  the  contrafted  vein  in  A  C  F  D  ;  the  cylindrical 
part  G I  N  M  has  its  diameter  MN,  greater  than  D  F.  By  the  reafoning  made  ufe  of  in 
the  preceding  propofition,  it  is  proved,  that  the  lateral  communication  of  motion  tends  to 
produce  a  vacuum  in  the  folid  zone  R  O  Y  S  X  QJT  Z.  If  the  communication  of  motion 
in  this  tube  were  completely  made,  it  would  follow,  that  the  preflure  of  the  atmofphere 
would  increafe  the  velocity  of  the  contraded  vein  in  the  ratio  of  D  F^  to  MN". 

But  the  form  itfelf  of  the  cylindrical  pipe  always  deftroys  a  notable  part  of  the  efFe£l : 
for  the  fluid  filaments  A  D,  in  turning  through  the  curve  D  R,  proceed  brifkly  to  ftrike 
the  fides  of  the  tube  G  M  at  R,  where  they  lofe  part  of  their  motion.  In  the  fpace  D  G  R 
eddies,  or  circular  whirls,  are  produced,  as  in  a  bafon  which  receives  water  by  a  channel. 
Thefe  eddies  are,  to  a  certain  extent,  a  failure  of  the  effe£t,  and  retard  the  efflux  of  the 
ftream.  A  much  lefs  increafe  of  the  expenditure  takes  place  in  the  cylindrical  tube  than 
would  anfwer  to  the  ratio  of  D  F^  to  M  N-. 

Experiment  XVIII. — A  notion  may  be  formed  of  thefe  internal  fhocks  and  eddies  in  the 
cylindric  tube,  and  their  effefts  on  the  efflux  of  the  fluid,  if  attention  be  paid  to  the  fol- 
lowing table  of  the  expenditure  through  the  diiferent  additional  tubes  in  the  horizontal 
pofition.  All  thefe  tubes  have  the  diameter  of  their  two  extremities  =18  lines ;  they  were 
all  provided  with  the  conical  tube  of  the  form  of  the  contra£led  vein  at  their  inner  extre- 
mity, excepting  that  of  fig.  6.  The  charge  was  always  32-5  inches  above  the  centre  of 
the  orifice. 

Viable  of  the  Times  employed  in  difcharging  Four  Cubic  Feet  of  Water  through  the  different 

Adjutages, 

Through  the  orifice  in  a  thin  plate,  -  -  -        41". 

Through  the  fimple  tube  of  fig.  6.  -  -  ,         31", 

Through  the  tube  of  the  form  of  fig.  5.  -  -         31". 

After  having  amended  (adouci)  the  conical  divergent  part,  D  F I G, 

of  the  fame  tube,  -  -  -  -         30". 

Through  the  tube  fig.  9.  -  -  -  -         V-"-^ 

Through  the  conical  tube  of  the  form  fig.  10.  -  -         27".J 

Through  the  tube  fig.  5.  the  portion  G  I  N  M  being  23.5  lines 
in  diameter,  and  84  in  length,  the  reft  as  before,  -         27''. 

It  may  perhaps  be  demanded,  whether,  in  the  internal  part  of  the  fimple  cylindric  tube 
K  L  V  of  fig.  6.  there  be  the  fame  augmentation  of  velocity,  and  the  fame  contra£l:ion  of 
the  ftream,  as  in  the  compound  tube  of  fig.  5.  ?  By  reafoning  according  to  the  principles 
we  have  eftablllhed,  I  think,  i.  That  in  the  fe£lion  K  L  of  fig.  6.  there  is  the  fame  increafe 
cf  velocity  as  we  have  feen  (Prop.  II.)  take  place  in  the  feclion  A  C  of  fig.  5.  The  direc- 
tion of  the  fluid  particles  which  pafs  through  thefe  two  feftions  mud  be  the  fame  in  both  . 
cafes,  becaufe  this  diredion  can  depend  only  on  the  impulfe  received  within  the  refervoir, 
which  is  the  fame  in  both.  2.  In  fig.  6.  the  fluid  particles,  after  having  pafled  through  the 
fettion  K  L,  begin  immediately  to  experience  the  effe£l  of  the  lateral  communication  of 
motion.    They  muft  therefore  deviate  laterally  through  the  curve  L  .f  2,  before  they  ar- 

3  I  a  rive 


4^4  Q"  ii(  Utet-al  Cummunlctitkn  of  Motlm  in  fluids, 

rive  at  the  place  of  contradion  which  they  aflunae  at  D  F>  fig.  5.  and  which  they  likewifd 
aflume  when  the  orifice  is  made  in  a  thin  plate.  If  we  imagine  a  tube  of  glafs^K,  one- 
extremity  of  which  is  applied  at  K,  fig.  6.  and  the  other  extremity  open  in  the  interior 
part  of  the  refervoir,  it  will  be  feen  that  the  preflure  of  the  atmofphere,  which  is  exerted, 
upon  the  coloured  fluid  T,  muft  likewife  adl;  on  the  furface  of  the  refervoir,  and  join  the 
preflure  of  the  fluid  in  the  refervoir  to  prefs  the  watei;  into  the  tube  y  K,  as  it  prefles  the 
coloured  liquor  into"  TS.  The  prefl'ure  of  the  atmofphere  muft,  in  the  fame  manner, 
augment  the  impulfe  of  all  the  fluid  particles  which  arrive  at  K  L,  and  confequently  mull 
increafe  the  expenditure. 

Since  the  checks  and  eddies  in  an  additional  cylindrlc  tube  muft  always  deftroy  a  part 
of  the  adlive  force  of  the  fluid,  it  follows,  that  the  fluid  column  iflTuing  out  of  the  tube 
tan  never  acquire  the  whole  velocity  which  is  due  to  the  a£tual  charge,  and  is  obferved 
.  Hcarly  entire  in  the  orifices  through  a  thin  plate ;  and  the  diminution  of  velocity  correfponds 
with  the  increafe  of  the  time  beyond,  that  ijodicated  by  the  theory,  a&  may  be  fecn  in  the 
following 

Evperlment  XIX.  The  orifice  P  fig.  i.  being  made  through  a  thin  plate,  andthe  vertical- 
height  P  M,  being  54  inches,  the  diftance  M,N  of  the  jet  was  81,5  inches,  fiaving 
applied  to  the  fame  orifice  the  cylindrical  tube  of  fig.  5.  and  the  perpendicular  P  M  being 
let  fall  from  the  external  orifice  of  the  tube,  the  dUlance  M  N  was  found  to  be  69  inches. 
According  to  the  theory,  the  expenditure  of  four  cubical  feet  through  this  tube  ought  to  have 
t^ken  place  in  26 '',24,  but  it  really  employed  31 ".  And.  the  proportions  31'' :  26''^,24  =s 
81,5  :  69  nearly. 

The  fame  obfervatlon  may  be  made  on  an  experiment  of  Michelotti  (torn.  ii.  pages  2? 
and  23].  P  M  being  19,33  f^^^j  ^"i^  '^^  water  ifluing  through  an  orifice  in  a  thin  plate  M  N 
was  23,2  feet  •,,  it  was  no  more  than  20  when  an  additional  cylindric  tube  was  applied 
which  had  not  even  the  proper  length. 

It  is  evident,  that  the  theory  of  the  lateral  communication  of  motion  mufb  likewife  apply 
in  the  fame  manner  to  defcending  and  afcending  tubes,  whenever  their  form  admits  of  thia 
lateral  communication.  In  defcending  tubes,  we  muft  add  the.  increafe  of  expenditure 
occafioned  by  this  caufe  to  that  which  is  produced  by  the  acceleration  of  gravity,  and. 
which  we  have  eftimated  in  Propofition  IV.  In  afcending  tubes,  gravity  a£b  in  a  contrary, 
direftion,  and  confequently  its  effeft  muft  be  deduced  from  that  of  the  lateral  commu- 
nication. Experiment  VII.  relates  to  afcending  tubes.  The  following  relate  to  other, 
pofitions. 

Experiment  XX.  The  tube  A  BEE  of  fig.  11,  Experiment  XV.  was  applied  in  the  place- 
of  the  tube  B  C  Q^,  in  fig.  7.  The  height  of  the  water  in  the  refervoir  above  the  • 
lower  extremity  of  the  tube  was  4 1,5  inches.  The  four  cubical  feet  of  water  were  emitted, 
in  az'"'. 

I  applied  the  fame  conical  tube  A  BFE,  fig.  11,  to  the  orifice  R,   fig.  8,  to  form  an: 
afcending  jet  a  little  inclined  from  the  perpendicular.      The  height  of  the  water  of  the  re- 
fervoir above  the  upper  extremity,  of  the  tube  was  23  inches.     The  expenditure  of  four 
cubical  feet  was  made  in  30", 

The  time  of  the  expenditure  in  Experiment  XV.  was  25''.     And  by  comparing  it  with 

the  prefent,  W£,find  nearly  V.^T^  ;  ^^^  =  25"  :.  2a".  And  V23  :  '^32^  =  25"  ; 
30". 


(Jn  tht  laUral  Communieation  of  Motion  in  Fluids.  425 

Experiment  XXI.  The  orifice  R,  fig.  8,  was  circular,  and  4,5  lines  in  diameter;  the 
charge  was  3 1,7  Inches,  and  the  jet  declined  a  little  from  the  perpendicular.  The  orifice 
being  through  a  thin  plate,  afforded  a  cubical  foot  of  water  in  161".  With  an  additional 
cylindrical  tube  of  the  fame  diameter,  and  ten  lines  in  length,  the  cubical  foot  of  water 
was  emitted  in  121". 

Under  a  charge  of  56  inches,  the  fame  orifice  afForded,  through  the  vertical  jet,  a  cu- 
bical foot  in  123"  through  the  thin  plate,  and  in  91''  with  the  fame  additional  tube. 

Thefe  two  refults  being  combined,  give  for  the  expenditure  of  vertical  jets  a  mean  ratio,- 
between  the  thin  plate  and  the  cylindrical  adjutage,  of  100  to  134,  which  is  alfo  the  ratio- 
between  the  horizontal  jets. 

Experiment  XXII.  I  applied  the  glafs  tube  QJl  T,  fig.  6,  to  the  point  S  fig.  5.  of  the 
compound  tube  A  C  M N,  the  diftance  B  S  being  24  lines.  In  this  fituation  the  fluid  T  no- 
longer  rifes  in  the  tube.  This  proves  that  the  lateral  tranflation  of  jhe  fluid  in  the  cylin- 
drical tube  is  made  very  near  the  place  where  the  vein  is  contrafted,  and  that  confequent- 
ly  D  R  muft  briflcly  flrlke  the  fide  G  M. 

By  this  experiment  we  fee  that  the  diftance  BR  to  which  the  oblique  filaments  ftrikc 
the  fides  of  the  tube,  does  not  amount  to  24  lines.  Suppofing  D  O  =  20  lines,  the  time 
which  the  particle  D  employs  to  pafs  through  the  fpace  D  O  in  my  experiments  is  lefs  than 
c",Oi.  Let  us  decompofe  the  curve-lined  motion  DR  according  to  the  lines  DO,  OR. 
Let  us  fuppofe  the  acceleration  through  O  R  to  be  uniform,  and  it  will  be  found  that  this 
acceleration  is  at  leaft  five  times  as  great  as  that  of  heavy  bodies.  If  the  lateral  force  through 
G  R  were  fimply  the  mutual  attraction  of  the  particles  of  the  water,  this  attraction  in  the 
particle  D  muft  not  only  overcome  the  inertia  of  the  particle  itfelf,  but  likewife  that  of  the 
other  particles  nearer  the  axis,  which  follow  D  in  its  deviation  through  D  R,  and  imprefs 
upon  them  a  much  greater  fum  of  acceleration  than  that  of  gravity.  Now  the  force  of 
attraction  of  one  particle  of  water  is  not  greater  than  the  natural  gravity  of  a  thread  of  wa- 
ter of  the  length  of  one  line  at  moft.  The  lateral  communication  of  motion,  which  is  the 
caufe  of  the  acceleration  through  O  R,  is  therefore  much  greater  than  could  have  been 
produced  by  the  mutual  attra£tIon  of  the  particles  of  water. 

Propejition  VII.  By  means  of  proper  adjutages  applied  to  a  given  cyllndric  tube,  it  Is 
pofllble  toincreafe  the  expenditure  of  water  through  that  tube  in  the  proportion  of  24  to- 
10,  the  charge  or  height  of  the  refervoir  remaining  the  fame. 
_  I  (hall  here  give  an  account  of  the  different  precautions  neceflary  to  be  taken  when  the 
expenditure  of  water  through  a  cylindrical  tube  of  a  given.  length  is  requiredto  be  the 
greateft  poffible. 

i.The  inner  extremity  of  the  tube  AD  (fig.  13.)  muft  befitted  at  A  B  with  a  conical  piece 
of  the  form  of  the  contra<3;ed  vein* ;  this  incrcafes  the  expenditure  as  12,1  to  10.  Every 
other  form  will  afford  lefs.  If  the  diameter  at  A  be  too  great,  the  contraction  will  be; 
made  beyond  B,  and  the  feCtion  of  the  vein  will  be  fmallcr  than  the  feCtion  of  the  tube. 

2.    At  the  other  extremity  of  the  pipe  B  C  apply  a  truncated  conical  tube  C  D,  of  which 

let  the  length  be  nearly  nine  times  the  diameter  C,  and  its  external  diameter  D  muft  be' 

1,8  C.      This  additional  piece  will  Increafe  the  expenditure  as  24  to  I2,i.     (Experiment 

XVI. )    By  this  means  the  quantity  of  water  will  be  increafed  by  the  two  adjutages  ABC  D, 

in  the.  proportion  of  24  to  10. 

♦  Boffur,,Art,  509. 

Att 


ij.j6  Water  Pipes,  lie.— 'Account  of  Booh. 

At  Rome,  the  inhabitants  purchafe  the  right  of  conveying  water  from  the  public  refer- 
voirs  into  their  houfes.  The  law  prohibits  them  from  making  the  pipe  of  conveyance  larger 
than  the  aperture  granted  them  at  the  refervoir,  as  far  as  the  diftance  of  fifty  feet  *.  The 
legiflature  was  therefore  aware,  that  an  additional  pipe  of  greater  diameter  than  the  orifice 
would  increafe  the  expenditure  ;  but  it  was  not  perceived  that  the  law  might  be  equally 
evaded  by  applying  the  conical  frullum  C  D  beyond  the  fifty  feet.  From  this  fecond  rule 
we  learn,  that  it  is  not  proper  to  make  the  flues  of  chimneys  too  large  in  the  apartments ; 
but  that  it  will  be  fufHcient  if  they  be  enlarged  at  their  upper  terminations,  according  to  the 
form  CD,  fig-  ^S-  This  divergency  of  the  upper  part  will  carry  off  the  fmoke  very  well, 
even  when  it  is  not  practicable  to  afford  chimneys  of  fufficient  length  to  the  upper  apart- 
ments.    The  fame  obfervation  is  applicable  to  chemical  furnaces  for  flrong  fire. 

3.  The  pipe  B  C  ought  to  be  ftraight,  without  elbows  or  curvatures.  To  the  experiments 
which  Boffut  has  made  on  this  headf  I  (hall  add  the  following. 

[To  be  continued.] 


ACCOUNTS    OF    BOOKS. 
Philofophical  Tranfaftions  of  the  Royal  Society  of  London,  for  the  Year  1798.    Part  II. 
Quarto.  593  pages,  with  a  Lift  of  Prefents  and  Index,  occupying  12  pages  more,  and 
17  plates.     Sold  by  Elmfly,  London. 

J.  H I  S  Part  contains  the  following  papers  :  10.  A  Difquifition  of  the  Stability  of  Ships, 
by  George  Atwood,  Efq.  — 11.  Quelques  Remarques  d'Optique,  principalement  relatives 
a  la  Reflexibilite  des  Rayons  de  la  Lumiere.  Par  P.  Prevoft,  Profeffeur  de  Philofophie  a 
Geneve,  de  TAcadcmie  de  Berlin,  de  la  Societe  des  Curieux  de  la  Nature,  et  de  la  Societe 
Royale  d'Edimbourg.  Communicated  by  Sir  Charles  Blagden,  Knt.  F.  R.  S. — 12.  An 
Account  of  the  Orifice  in  the  Retina  of  the  Human  Eye,  difcovered  by  Profeflbr  Soem- 
mering :  to  which  are  added.  Proofs  of  this  Appearance  being  extended  to  the  Eyes  of 
other  Animals.  By  Everard  Home,  Efq.  F.  R.  S.— 13.  A  Defcription  of  a  very  unufual 
Formation  of  the  Human  Heart.  &y  Mr.  James  Wilfon,  Surgeon.  Communicated  by 
Matthew  Baillie,  M.  D.  F.  R.S.  — 14.  Account  of  a  fingular  Inftance  of  Atmofpherical 
Refradlion.  In  a  Letter  from  William  Latham,  Efq.  F.  R.  S.  and  A.  S.  to  the  Rev. 
Henry  Whitfield,  D.  D.  F.  R.  S.  andA.S  (See  Philof.  Journal,  IL  417.)— 15.  Account 
of  a  Tumour  found  in  the  Subftance  of  the  Human  Placenta.  By  John  Clarke,  M.  D. 
Communicated  by  the  Right  Hon.  Sir  Jofeph  Banks,  Bart.  K.  B.  P.  R.  S. — 16.  On  the 
Roots  of  Equations.  By  James  Wood,  B.  D.  Fellow  of  St.  John's  College,  Cambridge. 
Communicated  by  the  Rev.  Nevil  Mafkelyne,  D.  D.  F.  R.  S.  and  Aftronomer  Royal.— 
17.  General  Theorems,  chiefly  Porifms,  in  the  higher  Geometry.  By  Henry  Brougham, 
jun.  Efq.  Communicated  by  Sir  Charles  Blagden,  Knt.  F.  R.  S. — 18.  Obfervations  of 
the  Diurnal  Variation  of  the  Magnetic  Needle  in  the  Ifland  of  St.  Helena  ;  with  a  Conti- 
nuation of  the  Obfervations  at  Fort  Marlborough  in  the  Ifland  of  Sumatra.  By  John 
Macdonald,  Efq.  In  a  Letter  to  the  Right  Hon.  Sir  Jofeph  Banks,  Bart.  K.  B.  P.  R.  S. 
— ig.  On  the  Corundum  Stone,  from  Afia.  By  the  Right  Hon.  Charles  Greville,  F.  R.  S. 
—20.  An  Enquiry  concerning  the  Chemical  Properties  that  have  been  attributed  to  Light. 
By  Benjamin  Count  of  Rumford,  F.  R.  S.  M.  R.  I.  A.     (See  Philof.  Journal  II.  400.)— 

*  Fontln.  de  aquseduft.  art.  205.  106  ct  iii.  f  Art.  631  et  feq. 

21.  Expe- 


Account  of  Scientific  Publ'icaiionj.  j^^f 

ai.  Experiments  to  determine  the  Denfity  of  the  Earth.  By  H.  Cavendifh,  Efq.  F.  R.  S.  and 
A.  S. — 22.  An  improved  Solutioti  of  a  Problem  in  Phyfical  Aftronomy  ;  by  which  fwiftly 
converging  Series  are  obtained,  which  are  ufeful  in  computing  the  Perturbations  of  the 
]\Iotioni>  of  the  Earth,  Mars,  and  Venus,  by  their  mutual  Attraction  :  To  which  is  added 
an  Appendix,  containing  an  eafy  Method  of  obtaining  the  Sums  of  many  flowly  converg- 
ing Series  which  arife  in  taking  the  Fluents  of  Binomial  Surds,  &c.  By  the  Rev.  John 
Hellins,  F  R.  S.  Vicar  of  Potter's  Pury,  in  Northamptonfhire.  In  a  Letter  to  the  Rev. 
Nevil  Mafkelyne,  D.  D.  F.  R  S.  and  Aftronomer  Royal. — 23.  Account  of  a  Subftance 
found  in  a  Clay-pit  j  and  of  the  EfFc£l  of  the  Mere  of  Difs  upon  various  Subftances  im- 
merfed  in  it  By  Mr.  Benjamin  Wifeman,  of  Difs,  in  Norfolk.  Communicated  by  John 
Frere,  t  fq.  F.  R.  8.  With  an  Analyfis  of  the  Water  of  the  faid  Mere.  By  Charles 
Hatchett,  Efq.  F.  R.  S.  In  a  Letter  to  the  Rt.Hon.  Sir  Jofeph  Banks,  Bart.  K,  B.  P.  R.  S. — 
24.  A  Catalogue  of  Sanfcrita  Manufcripts,  prefented  to  the  Royal  Society  by  Sir  William 
and  Lady  Jones.  By  Charles  Wilkins,  Efq.  F.  R.  S. — Prefents  received  by  the  Royal 
Society  from  November  1797  to  June  1798.— -Index. 

Cafes  of  the  Diabetes  Mcllitus,  with  the  Refults  of  the  Trials  of  certain  Acids  and  other 
Subftances  in  the  Cure  of  the  Lues  Venerea.  By  John  Rollo,  M.  D.  Surgeon  General^ 
Royal  Artillery.  Second  edition^  with  large  additions.  Odtavo,  62b  pages.  London^ 
Dilly,  17^8. 

An  account  of  the  firft  edition  of  this  excellent  treatife  was  given  in  the  firft  volume  of 
this  Journal,  page  285.  The  prefent  edition  is  greatly  enlarged  ;  but  the  time  of  receiving 
It,  and  other  circumftances,  prevent  me  from  giving  an  abftract  of  its  contents  at  prefent. 
The  chemical  reader  will  fee  with  pleafure,  in  one  of  the  articles  of  the  prefent  Number, 
that  Mr.  Cruicklhank  has  extended  his  refearches  into  the  nature  of  Sugar  and  Vegetable 
Mucilage.     See  page  406. 

L'Art  du  Blanchcment  des  Toiles,  Fils  et  Cotons  de  tout  Genre,  &c.  I/i  Englijlj.  The  Art 
of  Bleaching  Piece  Goods,  Thread  and  Cottons,  of  every  Defcription  ;  rendered  more 
eafy  and  general  by  means  of  the  Oxygenated  Muriatic  Acid  ;  with  the  Method  of  ren- 
dering Painted  or  Printed  Goods  perfedly  White  and  Colourlefs.   To  which  are  added,, 
the  moft  certain  Methods  of  Bleaching  Silk  and  Wool ;  and  the  Difcoveries  made  by  the 
Author  in  the  Art  of  Bleaching  Paper.     Illultrated  with  9  large  Plates  in  410.  reprc- 
fenting  all  the  Utenfils  and    different    Manipulations  of  the   Bleaching  Procefs :  An 
elementary  Work,  compofed  for  the  Ufe  of  Manufafturers,  Bleachers,  Dyers,  Caliieo 
Printers,  and  Paper-Makers.  By  Pajot  des  Charmes,  formerly  Infpector  of  Manufadurcs.. 
8vo.  202  pages.     Sold  by  Dugour  and  Durand,  Rue  et  Hotel  Serpente,  a  Paris. 
This  work  appears  to  be  of  fuch  great  praftical  utility  that  I  have  begun  a  tranflatton^ 
which  will  appear  in  the  courfe  of  the  winter,  with  additional  information,  which  I  hope 
to  procure,  refpefting  the  pradice  of  the  intelligent  manufadurers  of  our  own  country. 

Memoires  et  Obfervations  de  Chimie  de  Bertrand  Pelletier,  Dodeur  de  Medecine,  &c.;: 
Or,  Memoirs  and  Obfervations  in  Chemiftry,  by  Bertrand  Pelletier,  Dodor  of  Medi- 
cine, &c.  Colleded  and  arranged  by  Charles  Pelletier,  and  Sedellot  the  younger,  M.D» 
&c.  2  vols,  odavo,  with  5  plates,  and  a  portrait  of  the  Author.  Sold  at  Paris  by 
Croulebois,  Fuchs,  Barrois,  and  the  principal  bookfellers. 

Ttc  works  of  Pelletier  are  known  and  valued  by  every  fcientific  chemift.   Moft  of  them; 

liavc- 


49;8  Seientlfc  Puillciiite/is,  i^e, 

have  already  appeared  In  the  Annales  de  Chimie  and  Journal  de  Phyfiquc  i  but  this  C(A' 
lection  contains,  as  Lametherie  informs  us,  fome  new  articles  and  annotations  of  the 
author.  7  he  utility  of  fuch  colle£lions  is  obvious,  even  if  their  fole  objeft  were  to  form 
into  one  body  the  fcattered  productions  of  a  man  of  genius.  The  works  of  many  emi- 
nent writers  of  Meifloirs  have  loll  half  their  utility,  for  want  of  this  friendly  office  to 
fcience  and  to  pofthumous  fame. 

An  Englilh  Tranflation  of  the  late  Dr.  Stewart^s  "  Propofttlones  Geometrica  Mart  Veterum 
demonjiraia"  is  announced  for  publication  by  Mr.  Ley  bourn. 
It  confifts  of  a  feries  of  geometrical  theorems,  moftly  new,  inveftigated  firll  by  analyfis, 
and  afterwards  fynthetically  demonftratcd  by  an  inverfion  of  the  fame  analyfis.  The  uti- 
lity of  fuch  a  work  is  evident ;  and  the  celebrity  of  the  original,  which  is  now  fcarce,  will 
render  the  prefent  tranflation  more  valuable. 


From  a  paflage  in  the  Ekge  de  Leibnitz,  in  the  volume  of  the  French  Academy  for  17 15, 
and  in  the  firft  of  the  two  volumes  of  Eloges par  Foittentlle,  I  conclude  that  the  George  Dal- 
garu,  mentioned  in  page  345,  is  fo  named  by  an  error  of  the  prefs,  which  but  too  f'requently 
occurs  in  copying  proper  names  from  obfcure  manufcript.  His  name  appears  to  have 
been  Dalgarme.  I  (hall  give  the  paflage  in  Englilh,  on  account  of  its  curiofity  and  value. 
<See  page  493  of  the  laft-mentioned  work.) 

"  It  might  now  feem  as  if  we  had  exhaufled  the  fubjeG  of  the  labours  of  Leibnitz.  But 
"  this  is  not  the  cafe ;  not  becaufe  we  have  pafled  over  in  filence  a  very  great  number  of 
"  individual  fadts,  fufficient  to  have  eftablilhed  the  fame  of  any  other  man,  but  becaufe 
•'  what  remains  to  be  narrated  is  of  a  very  different  kind  from  what  we  have  already  given. 
**  It  is  the  project  of  a  Philofophical  and  Univerfal  Language,  which  he  had  conceived. 
<«  jyHkins  Bifliop  of  Chefler,  and  Dulgarme,  had  laboured  at  this  enterprife :  but  when 
**  Leibnitz  was  in  England,  he  obferved  to  Boyle  and  Oldenbeurg,  that  he  did  not  think  thofc 
"  great  men  had  followed  the  true  method.  They  might  caufe  nations  whofe  languages 
♦'  were  different,  to  communicate  together  with  eafe  ;  but  they  had  not  fcized  the  true 
"  real  chara£lers,vi\nch.  were  the  moft  delicate  inftrument  the  human  underftanding  could 
*•  avail  itfelf  of,  and  were  calculated  extremely  to  facilitate  the  procefTes  of  reafon,  the 
**  powers  of  memory,  and  the  invention  of  things.  Thefe  charafters  were  to  referable  as 
•'  much  as  poffible  the  charadters  of  Algebra,  which,  in  faO:,  are  very  firaple  and  very  ex- 
•*  preflive,  which  never  prefent  any  redundancy  or  equivocal  expreffion,  and  of  which  all 
"  the  varieties  are  demonftrative.  He  has  fomewhere  fpoken  of  an  alphabet  of  human  thoughts, 
**  which  he  meditated.  According  to  every  appearance,  this  alphabet  bore  relation  to  his 
"  univerfal  language.  After  the  difcovery  of  this,  it  would  have  been  alfo  neceflary  to  have 
*'  difcovered  the  art  of  perfuading  the  different  nations  to  ufe  it ;  and  this  would  not  have 
"  been  the  fmalleft  difficulty  of  the  talk."  With  regard  to  this  laft  art,  it  appears  to  me  to 
be  very  fimple,  and  capable  of  being  pointed  out  in  a  few  words.  On  this  fubjeft  the  readier 
may  confult  the  remarks  at  pages  189  and  191  of  our  prefent  volume. 


1 


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JOURNAL 


OF 

NATURAL    PHILOSOPHY,   CHEMISTRY, 

AND 

THE    ARTS. 


yjNUJRr    1799. 


ARTICLE   L 

Defcription  of  a  new  lt:Jlirument  for  drawing  eqnldijlant  and  other  parallel  Lines  ivith  great 
accuracy  and  expedition  ;  intended  principally  for  the  ufe  of  Engravers.  With  Specintcnt 
of  its  Performance.     By  W.  N. 

«3  O  M  E  mouths  ago  I  was  informed  by  the  Engraver  who  executes  the  plates  for  this 
Journal,  that  an  ingenious  artift  had  conftruded  a  machine  for  ruling  the  fhades  and 
grounds  of  copper-plate  engravings,  which  he  not  only  ufed  with  great  fuccefs  in  his 
own  bufinefs,  but  had  fold  to  others  under  an  engagement  of  fecrecy.  How  far  this  in- 
formation might  be  ftri(£lly  accurate,  was  of  lefs  confequence  at  the  time  this  converfation 
took  place,  than  the  confideration  that  it  would  be  eafy  to  make  fuch  a  tool,  and  render 
Its  advantages  more  general  by  publication.  I  then  promifed  to  make  one  ;  and  having 
now  finilhed  it,  I  take  the  earlieft  opportunity  of  communicating  it  to  the  world.  From 
the  preceding  hiftorical  ftatement,  the  reader  will  fee  that  I  have  no  claim  to  the  original 
thought  of  fubftituting  mechanical  operation  inftead  of  hand  work  in  this  department  of 
engraving ;  and  thofe  who  have  feen  the  fcrew  gear  of  Ramfden's  great  dividing  en- 
gine will  alfo  perceive,  that  1  have  done  little  more  than  diftribute  the  parts  of  this  tool 
ia  what  appeared  to  me  to  be  the  moft  fimple  and  convenient  manner. 

Fig.  I.  Plate  XX.  reprefents  the  inftrument  of  the  fize  of  that  which  I  have  made.  The 
outline  fe£lion,  fig.  2,  reprefents  the  fame  viewed  in  a  diredion  parallel  to  the  edge  0/ 
the  moveable  ruler.  The  letters  denote  the  fame  things  in  both.  A  A  A  A  is  a  frame 
fixed  to  the  drawing-board.  It  refembles  that  of  a  Aiding  rule,  and  ferves  to  guide  a 
Hiding  piece,  which,  lying  in  fig.  i,  immediately  under  the  fcrew,  could  not  with  con- 
venience be  denoted  by  any  letter.  B  C  is  a  fcre^  of  exadly  forty  threads  in  the  inch, 
but  might  conveniently  be  made  of  a  coarfer  thread.  G  H  and  E  D  are  two  cocks,  the 
former  of  which,  GH,  is  fixed  to  the  frame  A,  and  bears  a  clip  or  pair  of  nuts,  which 
open  and  (hut  with  a  joint  like  a  pair  of  compafles,  and  either  embrace  the  fcrew  by  a  re« 

Vol.  II.— Jan.  1799.  3  K  gularly 


430  -^'^y  Machine  for  ruling  engraved  Plates, 

gularly  tapped  part  when  (hut,  or  leave  it  at  liberty  when  open.    Fig.  3.  fhews  the  face  of 
this  cock  with  the  clip,  of  which  P  is  the  joint,  Q^Q__tapped  part,  R  a  pin  to  infure  their 
coming  up  fairly,  and  S  a  c';iw,  which,  when  drawn  upwards,  ferves  to  clofe  them ;  or, 
if  thrown  back,  leaves  them  at  liberty  to  open  by  the  action  of  a  fmall  fpiral  fpring,  let 
into  oppofite  holes  near  the  joint.     ED,  fig.  1,  reprefents  the  other  cock,  which  is  fixed 
to  the  Aiding  piece.     Jt  carries  the  llcel  ruler  E  F,  which,  though  fuihciently  ftrong,  is 
tJbin  enough  to  adapt  itfelf  to  ilight  variations  of  thicknefs  of  the  plate  beneath  it.     In  my 
inflrument  I  have  made  it  adjuftable  to  much  greater  variations  of  thicknefs,  by  means  of 
an  horizontal  axis  \   but  as  this  contrivance  adds  to  the  expence,  and  diminiflies  the  fim- 
plicity  of  the  inflrument,  I  would  rather  recommend  that  great  variations  fliould  be  al- 
lowed for  by  putting  paper  or  thin  flips  of  metal  underneath  the  plate  A  A,  as  may  be 
required.     The  end  C  of  the  fcrew  is  turned  down,  and  fixed  in  the  cock  ED  by  means 
of  a  nut  and  waflier  ;  or  in  any  other  of  the  methods  which  are  familiar  to  inftrument- 
makers.     The  upper  part  of  the  cock  ED  is  filed  round,  and  cut  into  teeth,  of  which 
£fty  would  complete  the  whole  circle.     The  centre  of  this  external  circular  part  corre- 
fponds  with  the  axis  of  the  fcrew  (fee  fig.  4  ).    L,  M  reprefent  two  fhort  cyhndrical  pieces 
which  are  hollow,  and  apply  to  each  other  fo  as  to  form  a  kind  of  box.    Within,  and  fixed 
to  the  part  M,  which  is  fixed  to  the  fcrew  itfelf,   there  is  a  ratchet  wheel  divided  into 
fifty  teeth  ;  and  within  the  part  L,  which  is  merely  fupported  by  the  cylindrical  part  or  ftem 
of  the  fcrewj  there  is  a  ratchet,  which  holds  when  the  part  L  is  moved  by  its  handle  N 
from  right  to  left,  but  efcapes  when  that  handle  is  moved  in  the  contrary  dire<3ion.     O 
is  a  lever,  or  arm,  likewife  fupported  by  the  flem  of  the  fcrew,  and  occupying  the  re- 
maining fpace  between  the   handle  N  and  the  cock  D.     At  the  outer  extremity  of  this 
lever  there  is  a  fmall  (leel  blade,  which,  by  means  of  a  back  fpring  exactly  refembling  that  of 
a  pocket  knife,  may  be  made  to  form  a  continuation  of  the  lever  itfelf,  or,  by  being  placed 
at  right  angles  to  the  lever,  m*y  be  made  to  refl  in  any  of  the  divifions  between  the  teeth 
of  the  circumference  of  the  cock  -,  and  confequentlyMvill,   by  that  means,  confine  the 
lever  to  the  pofition  in  which  it  is  placed.     The  handle  N  cannot  pafs  the  lever  O,  be- 
caufe  this  lafl  is  too  thick,  and  there  is  a  flud  or  pin  T,  fig.  4,  upon  the  face  of  the  cock 
D,  which  prevents  the  handle  from  being  moved  beyond  a  certain  determinate  ftation  to 
the  left  hand.     And,  laftly,  the  ruler  I  K,  which  is  reprefented  as  broken  off  at  K,  but 
(like  E  F)  may  be  of  any  required  length,  ferves,  by  means  of  a  thumb  fcrew  at  I, 
and  another  at  the  oppofite  end,  to  fecure  the  copper-plate  againft  the  drawing-board  ia 
the  ufual  manner. 

After  this  defcription  the  uie  of  the  apparatus  may  be  eafily  underftood.  By  drawing 
back  the  claw  S,  fig.  3.  the  fcrew  is  fet  at  liberty,  and  the  ruler  E  F  may  be  brought  to  any 
required  diflance  from  I  K  by  hand.  The  plate  may  then  be  duly  placed  and  fecured  to 
the  board,  and  the  clip  drawn  gently  together  by  the  claw  S.  In  this  fituation,  fuppofe  the 
lever  O  to  be  placed  at  a  confiderable  difl:ance  from  the  handle  N,  that  handle  may  be 
moved  to  the  right,  during  which  the  click  will  gather  upon  the  ratchet  wheel  j  and  then 
being  returned  to  the  left,  it  will  carry  the  fcrew  round.  The  gentle  prefTure,  exerted  by 
means  of  the  claw,  will  tend  to  clofe  the  clip  upon  the  fcrew,  as  foon  as  it  comes  into  a  fair 
pofition  by  its  rotation ;  at  which  inflant  the  claw  will  fuddenly  fall  into  its  place,  and  the 
machine  \%  ready  for  work,  excepting  that  the  adjuflmcnt  for  the  finenefa  or  coarfenefs  of 

the 


New  Machine  far  ruling  engraved  Plates.  431 

tl»e  (Iroke  mull  firil  be  made.  This  is  done  by  the  lever  O.  If  the  fteel  blade  be  dropped 
Into  the  firft  notch  beginning  on  the  left  hand,  the  handle  N  will  be  confined  ;  if  at  the  fc- 
cond  notch,  the  handle,  upon  being  moved  backwards  and  forwards  between  the  pin  T  and 
the  lever  O,  will  move  the  fcrew  through  one  tooth,  or  one- fiftieth  of  a  turn,  each  time, 
and  confequently  will  carry  the  ruler  F  througli  one  2000th  part  of  an  inch.  If  the  blade 
of  the  lever  O  be  placed  in  any  other  of  the  notches  (which  are  numbered  by  filing  the 
corners  of  every  fifth  notch),  the  quantity  pafled  over,  at  each  return  of  the  handle,  will  be 
greater  or  lefs  according  to  the  number.  As  there  are  but  twenty- fix  notches,  the  greateft 
fingle  fliift  of  this  inftrument  will  be  one-eightieth  part  of  an  inch ;  but  as  the  fliift  is  fo 
readily  made,  it  is  eafy,  even  with  this  fine  fcrew,  to  reach  greater  intervals,  by  moving  the 
handle  once,  twice,  or  even  three  times,  between  ftroke  and  firoke.  Thus  for  one-fiftieth 
of  an  inch,  or  ^  J-°^'^''**>  ^^^  number  of  intervals  cannot  be  pafled  over  at  one  fl;roke ;  but,  if 
the  blade  be  fet  at  the  twentieth  notch,  the  ruler  will  be  fliifted  exaftly  that  quantity  by 
two  movements  of  the  handle.  It  is  needlefs  to  multiply  diredtions  for  this  part  of  the 
operation ;  and  the  more  fo,  as  the  artift  is  much  more  likely  to  determine  the  finencfs  of 
his  fliadc  by  previous  trials,  which  will  render  him  acquainted  with  the  inftrument,  than  by 
4ny  numerical  computation. 

An  inftrument  like  the  prefent  may  alfo  be  ufefully  employed  in  fubdividlng  lines  into 
fmall  parts.  If  curved  lines  be  required  to  be  drawn  at  equal  diftances  from  each  other, 
the  fimpleft  method  appears  to  be  that  of  varying  the  figure  of  a  temporary  edge  of  horn 
or  metal,  which  may  be  fixed  to  E  F  :  and  if  lines  be  required  converging  to  a  point,  the 
ruler  E  F  may  be  made  to  occupy  the  radius  of  a  circle  of  any  magnitude  whatever,  by 
giving  an  adjuftable  angular  figure  to  the  Aider,  and  cauGng  it  to  move  againft  two  points, 
upon  principles  deduced  from  the  thirty-firft  propofition  of  F.uclid's  third  book. 

As  this  inftrument  was  made  at  intervals  of  Icifure,  without  any  account  being  kept  of 
time  or  materials,  I  cannot  diftinflly  ftate  the  coft  :  but  I  eftimate  that  the  whole  being 
made  of  brafs  and  fteel,  and  well  finiftied,  with  a  fmall  drawing-board  and  the  wooden 
holding  piece  I  K,  might  be  afforded  by  a  ftiopkeeper  in  the  mathematical-inftrument  buG- 
nefs  for  ten  guineas.  If  the  frame  and  Aider  were  of  box- wood,  which  I  have  no  doubt 
would  anfwer  very  well,  and  the  ornamental  covering  LM  of  the  ratchet-wheel  were  omit- 
ted, I  fuppofe  the  inftrument  could  be  afforded  for  confiderably  lefs  than  half  that  fum. 

The  engraver  has  ufed  this  apparatus  in  the  plates  of  the  prefent  number. 


II. 

Memoir  on  the  Qimate  of  Ireland.  By  the  Rev.  JVjLLIAM  HAMILTON,  of  Favet,  in  the 
County  of  Donegal;  late  Fellonu  of  Trinity  College,  Dublin;  M.R.I.A.  Correfpondifi^ 
Member  of  the  Royal  Society  of  Edinburgh,  is'c 

[Concluded  from  Page  386,  Vol.  II.] 
Of  the  EffeBs  ofthefe  We/fern  Tempejls  on  the  General  Temperature  of  the  Climate. 


I 


N  a  paper,  honoured  with  a  place  in  the  fecond  volume  of  the  Tranfa£lions  of  the 
Academy,  I  recorded  the  refult  of  fome  experiments  made  in  the  year  1788,  for  the  pur- 
pofe  of  afceitaining  the  temperature  of  the  earth  in  our  latitudes. 

31^2  From 


43  2  ^"  i^t  equable  Tempemtt/ft  of  the  Iri/Jj  Climate, 

From  thefe  experiments  it  -appears,  that  the  medium  temperature  of  the  kingdom  of 
Ireland,  from  its  fouthern  to  its  northern  extremity,  nearly  coincides  with  the  (laiidard 
alfigned  to  correfponding  degrees  of  latitude  in  Mr.  Kirwan's  ingenious  tables*. 

It  is  further  difcoverable,  that  the  general  warmth  of  our  ifliuul  is  in  no  ref^^eft  inferior 
to  that  of  other  countries  in  its  parallel :  from  whence  we  are  naturally  led  to  conclude, 
that  the  annual  quantity  of  heat  received  here  is  not  lefs  in  our  day  than  it  was  in  former 
ages. 

If  thefe  things  are  fo,  it  may  be  denietl  that  there  is  any  fubftantial  foundation  for  the 
frequent  complaint  of  change  in  our  feafons.  The  ocean  may  be  agitated  by  ftormsi 
fands  be  drifted  along  our  coafts,  and  trees  blafted  in  mountainous  and  expofed  fituations;, 
but  why  fliould  the  farmer  lament  the  diminiflied  ardour  and  fliortened  period  of  his 
fummers,  as  if  winter  pofTcfred  more  than  its  natural  portion  of  the  revolving  year  .' 
Whence  fliould  atife  the  gardener's  complaints,  that  his  peaches,"  however  fheltered  from 
ftornis,  rarely  now  arrive  at  maturity  ;  and  tl.at  his  IV'ay-duke  cherries,  even  in  the  moft 
favoured  afpe£ls,  no  longer  merit  that  diftinguifhed  title  ? 

May  I  be  permitted  to  aflume,  as  true,  the  h£l  which  it  has  hitherto  been  the  purpofa 
of  this  paper  to  demonftrate,  and  in  fupport  of  which  the  trees,  the  fands,  and  the  tidea 
of  our  iiland  feem  to  bear  conftant  and  unequivocal  teftimony ;  namely  that,  of  late 
years,  the  weftern  winds  have  blown  with  increafed  violence  ?  From  that  fingle  principle 
an  anfwer  may  be  deduced  to  all  thefe  interelting  queRions. 

It  is  a  matter  well  known,  and  eafily  to  be  exphuncd,  that  the  furface  of  the  ocean  va- 
ries, lefs  from  the  mean  annual  temperature  of  its  latitude,  than  land  in  the  fame  parallel  f: 
that  is,  the  furface  of  the  fea  is  colder  in  fummer,  and  warmer  in  winter,  than  the  fur- 
face  of  the  ground  in  that  latitude. 

If  then  the  prevalent  winds  of  any  country  blovc  over  an  ocean  fituated  in  its  parallel, 
that  country  will  relatively  be  denominated  temperate  •,  it  will  be  free  from  all  extremes  j. 
the  heats  of  fummer  and  the  colds  of  winter  will  be  checked  by  fea  breezes  of  a  contrary 
property;  and  the  land,  influenced  by  the  neighbouring  element,  mufl:,  more  or  lefs,  par*- 
take  in  its  equability  of  temperature. 

Such  is  the  cafe  in  almod  all  the  iflands  of  the  world :  and  fuch  from  immemorial  ages 
has  been  the  peculiar  character  of  Ireland.  Hither  come  the  weftern  winds,  modified  by 
the  temperature  of  the  broad  Atlantic  ocean,  which  they  traverfe  in  their  career  :  hither 
fly  the  clouds,  teeming  with  moifture  colle£led  in  a  courfe  of  three  thoufand  miles  along 
its  furface  ;  and  here  uniformity  of  temperature,  and  redundant  humidity,  have  always 
been  marked  as  the  diftinguiflied  charafter  of  our  foil. 

Since  then  the  trees,  the  fands,  and'  the  tid^-demonftrate  that  thefe  winds  have,  of 
late  years,  blown  with  unufual  violence  ;  fince  they  bear  teftimony  that  a. large  quantity 
of  air  thus  dire£led,  thus  tempered,  and  furcharged,  has  pafled  over  our  lands  ;  it  plainly 
follows  that  the  climate  muft  have  felt  the  change ;  that  it  muft  have  experienced  colder 
fummers  and  milder  winters  than  heretofore,  approaching  towards  that  equabihty  of  heat 
and  redundance  of  moifture  which  the  farmer  and  the  gardener  at  prefent  fo  heavily  la- 
ment. 

JJut  it  is  not  from  increafe  of  quantity  alone  that  thefe  wiods  Iiave  produced  their  effefl:*. 

•  See  Kirwaa's  Efiimatt  of  Temperatures.  I  Ibid. 

They 


X)n  the  rqualU  Temperaime  of  the  Irijh  Clmme,  43  j 

They  have  altered  the  temperature  of  the  ocean  itfelf ;  and  thus  have,  as  it  were,  muhi- 
plied  their  changeful  influence  on  the  land ;  adling  there  at  once  with  new  properties,  as 
well  as  with  increafed  quantity. 

The  furface  of  water  in  a  {late  of  tranquillity  admits  of  greater  variations  of  tempera- 
ture than  in  a  (late  of  agitation.  It  may  become  much  hotter  in  fummer  and  colder  in 
winter  when  calm  than  when  didurbed  ;  for  the  particles  at  the  furface,  when  heated  or 
eoolcii,  do  not  immediately  give  place  to  others  nearer  the  bottom  ;  the  procefs  of  com- 
mixture, in  a  tranquil  (late,  is  gradual,  and  the  tranfmiffion  of  change  fomewhat  re- 
femblcs  the  flow  and  retarded  progrefs  that  takes  place  on  the  land.  Agitation  always 
counteradls  this  gradual  procefs;  a  rapid  commixture  of  the  particles  produces  a  quick. 
aflTmiilation  of  temperature  throughout  the  whole  niafs,  and,  thus  taking  away  all  partial 
excefs,  reduces  the  whole  toward  a  medium  (late  of  uniformity. 

Thus,  fummer  tempefts  always  tend  to  dimlnifli  the  fuperficial  heat  of  an  ocean  over 
•which  they  ru(h ;  while  winter  blafls,  agitating  the  waters  at  confiderable  depths,  refift' 
the  natural  cold  of  the  feafon  by  a  fupply  of  relatively  warm  particles,  which  arife  from 
tlie  bottom  toward  the  furface. 

That  the  Atlantic  ocean,  the.  vaft  and  potent  arbiter  of  our  feafons,  has  fufFered  un- 
ufual  agitation  of  late  years,  feems  evident  from  the  natural  phenomena  recorded  in  the  be- 
ginning of  this  Memoir.  The  trees  and  fands  of  our  iflaiid  bear  teflimony  to  the  dorms 
which  fweep  along  its  furface  ;  and  the  tides  come  to  us  as  frequent  and  unerring  mef- 
fengers  of  the  tumultuous  and  agitated  (late  of  its  billows  attendant  on  their  furious  "fcareer. 

From  this  perturbed  abyfs  of  waters  has  arifen  an  unceafing  influence,  equally  potent 
to  check  the  ardour  of  the  fummer  folar  beams,,  or  to  relax  the  (hackles  of  a.  northern 
winter.  By  this  prevailing  influence,  fummer  has  been  rendered  impotent  to  raife  and 
ripen  many  of  our  crops  j.and  the  farmer,  taught  by,  neceffity,  learns  now  to  hand  them 
over  ready  grown,. and  prepared  for  the  maturity  of  fummer  under  the  mild  temperature 
of.  an  Atlantic  winter.  Hence  too  the  gardener  has,  of  late  years,  been  compelled  to  call 
in  the  aid  of  artificial  heat  to  forward  the  peach,  the  ne£larine,  the  grape,  and  every  othef 
fpecies  of  delicate  fruit  to  perfe6lion. 

Hence  premiums  now  vainly  attempt  the  growth  of  hemp,  which  formerly  peafants,  in 
the  mod  northern  counties  of  Ireland,  cultivated  without  reward  around  their  cabins  for 
domedic  ufe.  And  hence  the  ancient  apiaries  of  our  ifland,  once  fo  celebrated,  and 
guarded  with  fuch  fpccial  and  minute  attention  by  the  Brchon  laws  *,  are  now  extinft ; 
and  honey,  from  being  a  common  article  of  popular  confumption,  has  becoine  a  rare 
luxury,  or  an  expenfive  medicine. 

Winter  has  likewife  felt  the  general  influence  of  this  Atlantic  temperature;  our  grafles 
fcarcely  droop  beneath  the  frofls ;  wheat  and  oats  vegetate  in  the  open  fields  during  the 
very  folftice  itfelf;  myrtles  and  laurels,  in  fheltered  fituations,  brave  the  feverity  of  winter  ; 
the  Foyle,  and  other  large  rivers  of  the  northern  province,  frequently  fubjeft  to  the  icy 
chains  of  former  ages,  now  run  in  uninterrupted  freedom  f' 

*  See  Colleftanea  dc  Reb.  Hib.  Tranfl,   Brehon  Laws. 

•|-_  Fifty  years  have  clapfed  fince  the  river  Foyle  has  been  tffeQually  frozen  over  at  Derry.  It  is  alfo  ob- 
ferved  that  the  river  Thames,  in  Britain,  is  lefs  frequently  frozen  of  late  years  than  formerly.  See  Aichaeo- 
logia  Britannica,  vol.  iii.  p.  55. . 


434-  Coiifequences  of  the  equable  Temperature  of 

FaiSs  fuch  as  tliefe  are  to  be  confidered  as  the  bafis  of  general  opinion  conceruing  the 
alteration  of  our  climate  ;  while  old  age,  connet£ling  thefe  appearances  with  the  fragility 
of  declining  life,  and  a  decayed  conftitution,  has  become  querulous  in  proportion  to  its 
feelings,  and,  judging  of  external  phenomena  by  the  exaggerated  teft  of  its  own  acute 
fcnfations,  emphatically  pronounces  that  the  feafons  are  now  kfs  favourable  than  for- 
merly. 

On  the  Confequences  of  this  Equability  of  Temperature  to  /inimal  and  Vegetable  Life. 

FROM  the  tranfient  perufal  of  this  Memoir,  a  rapid  and  impatient  mind  would  pro- 
bably draw  numberlefs  falfe  conclufions.  The  fa61:s  here  recorded  feem  to  wear  a  gloomy 
afpcfl;  to  mark  a  gradual  deterioration  of  our  feafons;  to  indicate  a  climate,  harfh,  un- 
genial,  and  of  confequence  fterile  in  its  nature  ;  clouded,  humid,  tempeftuous,  cheerlefs^ 
and  unf  iendly  to  animal  and  vegetable  life. 

All  thefe  conclufions  contradi£l:  experience,  and  may  be  overturned  by  a  calm  confideraw 
tion  of  the  phenomena  themfelves. 

Experience  teaches  us  that  dry  feafons  and  eafterly  gales  arc,  in  our  ifland,  invariable 
fources  of  feeble  yeg*etation  and  numerous  difeafes*;  and  the  hiftory  of  the  world  informs 
us  that  winds,  whether  hot  or  cold,  are  in  their  nature  deleterious  to  animal  and  vegetable 
life,  in  proportion  as  they  become  deprived  of  humidity.  The  warm  air  of  the  African 
defert  breathes  defolation  over  the  parched  land  of  Egypt  and  Syria,  before  it  is  yet  felt  is 
a  tempeft  f.  Even  our  own  wefterly  winds,  the  Atlantic  meflengers  of  health  and  fer- 
tility to  our  ifland,  after  traverfing  the  cold  and  dry  trail  of  the  vaft  Siberian  continent, 
bear  nothing  but  flerility,  and  almoft  perpetual  winter,  to  the  unhappy  climate  of  Kam- 
fchatka  %. 

Heat  or  cold  in  extremes,  dry  air  in  rapid  motion,  and  molft  air  in  a  ftagnant  Hate,  feem 
to  be  the  principal  external  fources  of  human  difeafes;  and  climates  are  generally  found 
favourable  to  health  and  longevity  in  proportion  as  they  are  exempt  from  thefe  natural 
caufes  of  diforder  and  decay. 

It  ought  therefore  to  be  inferred,  a  priori,  that  Ireland,  celebrated  for  the  fingular  equa- 
bility of  its  temperature,  and  the  ceafelefs  motion  of  an  atmofphere  always  influenced  by 
the  moifture  of  the  Atlantic,  fhould  be  likewife  charafteriftically  free  from  natural  difeafe  j 
and  experience  proves  that  this  conclufion  is  true. 

The  exhaufting  agues  of  North  America,  or  the  fens  of  England  § ;  the  fatal  fluxes 
•which  prevail  in  the  low  countries  of  the  continent  of  Europe;  the  dreadful  bilious  dif- 
tempers  of  both  the  Indies ;  the  peftilence  which  defolates  the  African  and  Afiatic  cli- 

*  Of  this  the  influenza,  attendant  on  the  caflcrly  winds   of  Tpring  in  the  prefent  year  ('"95),  affords 
a  ftrong  inftance. 

■f  See  Volney's  account  of  Egypt  and  Syria. 

J  The  latitude  of  Kamfchatka  corrcfponds  with  that  of  Ireland  ;  the  wefterly  winds  are  prevalent  in  each ; 
yet  the  former  experiences  a  rigorous  winter  of  nine  months,  and  the  latter  rarely  of  as  many  days.  See 
Cook's  Voyage  in  1 779,  vol.  iii.  ch.  6. 

§  The  ague  is  fo  rare  in  feveral  parts  of  Ireland,  that  inany  pcrfons  arc  totally  unacquainted  with  it.  In  the 
northern  province  the  author  has  never  met  with  the  difeafe,  and  its  exiftence  there  is  generally  denied. 

mates. 


Trtland  uptn  Animal  ani  VegrtabU  Liff,  435 

mates,  are  all  either  entirely  unknown,  or  but  feebly  felt  in  Ireland.  There  is  here  no  cha- 
Ta£leriftic  difeafe  to  mark  the  natural  fource  of  unhealthfulnefs.  There  are  few  dlforders 
•which  cannot  be  diredly  traced  up  to  feme  artificial  caufe ;  to  feme  intemperance,  to 
feme  negled,  to  fome  excefs,  either  of  luxury  or  penury,  in  the  fuffering  fubjc£l.  Manu- 
fadlures  in  their  kind  unwholefome,  induflry  exerted  beyond  its  proper  limits,  irregularity 
of  food  or  fermented  liquors,  illicit  amours,  colds,  the  confequence  of  folly  or  inattention, 
excefs  or  deficiency  of  proper  exercife,  anxiety  and  fretfulnefs  of  mind,  together  with  the 
copious  lift  of  cafualties,  afford  to  the  phyfician  of  this  country  the  caufes  and  explana- 
tion of  almoft  all  its  difordcrs. 

From  its  peculiar  falubrity,  the  natives  of  this  ifland  are  celebrated  through  Europe  for 
juft  fymmetry  of  proportion  and  an  athletic  frame ;  becaufe,  from  earlieft  infancy  to  man- 
hood, a  check  is  rarely  given  to  the  progrefTive  increafe  of  animal  ftrength,  or  the  natural 
and  appropriate  forms  of  an  undifeafed  body.  From  the  fame  hygeian  fource  flow  thofe 
ardent  paffions,  thofe  exuberant  ftreams  of  animal  fpirits,  which  render  our  natives  al- 
ways cheerful,  oftentimes  turbulent  and  boifterous,  the  ufual  confequences  of  uninter- 
rupted health  and  a  vigorous  conftitution.  Hence  wild  adventure,  perfonal  courage,  im- 
petuofity  of  purfuit,  inattention  to  confequences,  and  improvidence  of  difpofition,  become 
the  charafteriftic  features  of  minds  feldom  under  the  influence  of  that  anxiety,  which, 
flying  from  the  prefent  moment  and  its  enjoyments,  watches  for  futurity,  and  pants  after 
remote  felicity. 

The  general  temperature  of  our  climate,  in  the  vicinity  of  the  capital,  is  fomewhat 
lower  than  the  50th  degree  of  Fahrenheit's  thermometer*  ;  and  a  mean  of  the  hotteft  or 
coldefl  months  of  our  year  rarelv  varies  more  than  ten  degrees  from  this  ftandard  heatf. 
Winter  therefore  with  us  is  ufually  accompanied  with  a  temperature  of  forty  degrees, 
fpring  and  autumn  of  fifty  degrees,  the  fummer  of  fixty  degrees  of  the  thermometer ;  and 
the  general  heat  of  any  fingle  month  of  thefe  feveral  feafons  feldom  varies  much  fiom  the 
correfponding  temperature  of  that  particular  feafon  to  which  it  belongs. 

Of  thefe  limits  the  loweft  is  not  fufliciently  cold  to  check  the  growth  of  any  of  the  na- 
tural herbage  of  our  ifland,  nor  the  higheft  powerful  enough  to  parch  the  furface  of  a  moift 
foil,  or  to  fcorch  its  luxuriant  grafles.  Hence  it  comes  to  pafs  that  our  fields  maintain  a 
perpetual  verdure,  unimpaired  by  either  folftice.  Hence  too  the  farmer  is  enabled  to  lay 
his  lands  under  grafs  almoit  at  any  feafon,  even  at  the  commencement  of  winter  J  :  and 
hence  the  grazier  never  lofes  the  benefit  of  his  rich  paftures  at  any  period  of  the  year, 
unlefs  during  the  tranfient  paflage  of  a  temporary  drift  of  fnow ;  fo  that  horfes,  cattle, 
and  fheep,  arrive  here,  with  little  care,  at  a  degree  of  perfedlion  unattainable  in  other 
countries  without  infinite  experice  and  trouble. 

For  the  growth  of  flax,  the  ftaple  comrpodity  of  the  kingdom  ;,  of  potatoes,  the  general 
food  of  its  inhabitants  ;  and  of  barley,  from  whence  the  ardent  fpirits  and  other  fermented, 
liquors  of  the  country  are  derived  ;  the  climate  feems  to  poflefs  a  peculiar  felicity  of  tern- 


•  See  Hamilton's  paper  on  the  temperature  of  Ireland,  in  the  fecond  volunie  of  thefe  Tranfaftions. 

f  See  State  of  the  Weather  in  Dublin,   from  J 
'ranfaftions. 

J  See  Young's  Tout  in  Ireland,  Yol.  I.  p.  130, 


f  See  State  of  the  Weather  in  Dublin,   from  JUne  1791  to  June  1793,  by  Mr.  Kirwan,  Vol.  V.  of  theft-- 
Tranfaftions.  ' 


peraturc^ 


43'5  Equailt  Temperature,  Populuthn,  t^c.  af  Ji  eland, 

perature,  and  moift  in  all  its  feafons ;  and  for  their  ncccflary  degree  of  ripenefs  the  heat 
of  fummer  is  dmply  fufficient. 

It  is  for  the  more  delicate  fpecies  of  garden-fruits,  for  ill  condu£led  crops  of  oats  in 
bleak  and  mountainous  fituations,  and  for  ihe  complete  and  perfedl  maturity  of  wheatj 
that  uneafy  apprehenfions  can  ever  be  entertained  by  the  gardener  or  the  farmer. 

The  former  are  in  themfelves  of  little  importance;  and,  where  fuch  luxuries  are  re- 
quired, glafs  coverings  and  artificiai  heat  afford  an  ample  fupply,  and  remove  all  pre- 
tence for  dlfcontent.  Human  art  and  induftry,  attentive  to  circumftances,  and  accommo- 
dated to  times,  has  rtolen  from  the  mild  temperatures  of  our  Ysfinters  as  much  warmth  as 
ferves  to  compenfate  for  the  deficiency  of  fummer  heats  in  forwarding  and  perfefling  the 
crops  of  wheat ;  and  a  little  will  teach  the  farmer  in  our  mountainous  provinces  to  ufe  thtf 
fame  (wtifice  with  refpeft  to  his  oats,  whenever  neceffity  fhall  demand  his  increafed  at- 
tention. 

To  fum  up  matters  then  with  truth  and  brevity— A  denfity  of  population,  furpaiTmg 
that  of  tlife  vaunted  millions  of  undepopulated  France  *  ;  a  copious  export-trade  in  pro- 
vifions  of  various  kinds,  unequalled  by  any  kingdom  whofe  inhabitants  are  proportionably 
numerous  f  ;  and  a  ftaple  manufaclure,  unrivalled  in  general  ufe,  in  certainty  of  produce, 
and  intrinfic  value  :j: ;  are  circumftances  which  have  not  fallen  to  the  lot  of  other  nations, 
and  bring  with  them  clear  and  irrefragable  evidence  to  demondrate  a  falubrious  country, 
a  genial  climate,  and  a  fertile  foil  in  Ireland. 

*  The  inhabitants  of  Ireland  amount  to  more  than  four  millions.  (See  Mr.  Buflie's  Memoir,  Irifli  Tranf, 
Vol.  III.) 

Hence  the  denfjty  of  its  population  is  at  the  rate  of  iSz  perfons  to  a  fquare  geographical  mile,  fuppofing  the 
jiland  to  contain  in  round  numbers  za.ooo  fuperficial  miles. 

Mr.  Zimmerman,  In  his  Political  Survey  of  Europe,  erroneoufly  fuppofing  the  inhabitants  of  this  country 
lefs  than  two  millions  and  a  half,  deduces  a  denfity  of  population  only  to  117  perfons  on  each  mile.  The  foU 
lowing  table  marks  the  number  of  individuals  on  a  geographical  fquare  mile  in  the  northern  countries  of  Eu- 
rope, as  taken  from  Zimmerman's  tables  (Ireland  being  correiSed) ;  from  whence  it  will  appear  that  thi$ 
kingdom  rates  extremely  in  the  denfity  of  its  population. 

Perfonf. 

Denmark  -  r  -         iz 

Sweden  ■  -  -  •  14 

Rulfia  -  -  -         10 

Scotland  -  -  -51 

Poland  -  -  -53 

Prudia  -  -  -         67 

England  -  -  -       119 

Germany  .  -  -       135 

France  -  -  -       151 

Ireland  ...       igj 

Holland  ...       136 

.J.  Two  hundred  and  twenty  thoufand  barrels  of  beef  and  pork,  independent  of  the  various  matters  connefted 
therewith,  and  of  every  other  fpecies  of  provifion,  were  exported  in  the  year  ending  15th  March  1793. 

J  After  a  progreffive  increafe  of  ninety  years  the  exports  of  linen-cloth  alone,  in  the  year  1792,  amounted 
to  forty-three  million  yards,  from  one  million  only  at  the  commencement  of  tlie  prefcnt  century. 

Conclusion.  - 


Zuppofed  Coufes  of  Chttngt  bf  Climaie  in  Ireland.  4yj' 

Conclusion. 

IN  this  Memoir  I  have  endeavoured  to  prove,  from  natural  and  almoft  incontrovertible 
rcgifters  of  .the  phenomena  of  later  years,  that  the  winds,  and  particularly  the  weftera 
ftorms,  have  fwcpt  with  Increafed  violence  over  Ireland. 

From  this  faft  I  have  deduced  a  neceflary  change  in  its  climate  ;  a  more  general  equa- 
feility  of  temperature  through  the  year ;  fummers  lefs  warm,  and  winters  more  mild  and 
open :  and  ladly,  I  have  endeavoured  to  fupport  this  conclufion  by  general  obfervation, 
and  the  enumeration  of  particular  inftances  where  the  defe£t  of  fummer  heat,  and  winter 
ice,  feem  to  be  the  moll  (trongly  marked. 

One  queflion  ftill  remains  curious  in  its  principle,  and  interefting  in  its  folution — Why 
have  thefe  weftern  winds  blown  with  unufual  and  increafed  violence  ? 

The  limits  of  a  Memoir  fuch  as  this  do  not  permit  me  to  enlarge  on  this  fubjeft,  and  even 
«ppcar  to  include  a  reproof  for  the  length  of  the  prefent  interruption.  I  fhall  therefore  tref- 
pafs  no  longer  on  the  moments  of  the  Academy  than  to  fugged  a  few  queries,  which  maf 
ftand  over  for  future  confideratlon  ;  leaving  it  to  time,  and  the  ingenuity  or  better  directed 
obfervations  of  others,  to  verify,  to  difprove,  or  to  condemn,  the  hints  which  may  be  con- 
lained  in  them. 

ift.  Have  not  our  winds  become  more  violent,  and  the  temperature  of  our  feafons  more 
equable,  fince  the  forefts  of  Ireland  were  cleared,  and  the  country  cultivated  ?  And  have 
not  thefe  winds,  and  that  equability  of  temperature,  been  nearly  proportioned  to  thcfc  as  t* 
their  caufes  ? 

2d.  Have  not  fimilar  changes  occurred  under  analogous  circumftances  in  North  America  y 
even  in  Canada,  that  country  of  extremes  in  heat  and  cold  ?    And  did  not  the  ifland  of 
Bermudas,  though  fituated  fo  much  to  the  fouthward  of  us,  become  barren  of  fruit  in  con- 
fequcnce  of  the  deftru£lion  of  its  timber-trees  ? 

3d.  Has  it  not  appeared  from  obfervations  on  the  afcent  of  balloons,  and  the  motion  of 
clouds,  that  the  lower  mafs  of  air  often  purfues  a  different  courfe  from  the  upper  ftratum  • 
May  not  then  the  limits  of  our  ftormy  currents  of  air  be  often  confined  within  a  few  hun- 
dred yards  of  the  furface  of  the  earth  ?  And  if  fo,  is  it  not  poffible,  and  even  probable, 
that  the  frequent  interruption  of  forelts  and  groves,  and  hedge-row  trees,  might  have  for- 
merly very  much  retarded,  and  finally  checked,  the  progrefs  of  a  tempeft  ? 

4th.  Have  not  all  the  countries  of  Europe,  Afia,  and  America,  within  the  parallel  of 
Ireland,  been  very  much  denuded  of  their  forefts  within  the  prefent  century  .'  And  has 
not  the  increafed  velocity  of  the  wefterly  winds  been  proportioned  to  this  deftruftion  oi 
the  forefts  and  trees,  as  to  their  natural  caufes  ? 

5th.  Is  it  not  probable,  fince  the  prevalent  winds  of  our  parallel  have  a  wefterly  ten- 
dency, that  circumftances  which  have  removed  impediments  to  their  career  round  the  en- 
tire globe  would  give  increafed  velocity  to  their  courfe  ? 

6th.  Should  not  Ireland,  launched  as  it  is  into  the  Atlantic  beyond  the  other  coafts  of 
Europe,  and  denuded  as  it  has  been  of  forefts  and  hedge-row  trees,  be  moft  fenfibly  af- 
fected by  increafing  tcmpefts  from  the  weft,  and  the  firft  to  experience  their  influence 
cm  its  climate  ? 

Whether  thefe  queries  have  any  foundation  in  nature,  or  are  merely  to  be  efteemed  the 

refult  of  an  unreftrained  imagination  ;  whether  fo  diminutive  an  animal  as  man,  fo  tem- 

VoL.  11.— Jan- 1799-  2^  P°"*y 


jljg.  ^Umaie  of  Irehxd. — Ek&rtctty 

porary  in  duration,  fo  impotent  in  flrength,  afl;ing  through  the  lengthened  period  and  per* 
fevering  efforts  of  a  large  portion  of  his  fpecies,  can  reafonably  be  deemed  equal  to  the  in-' 
voluntary  produdtlon  of  fuch  vaft  effefts  ;  to  a  change  even  of  the  elements  and  climates 
of  the  earth,  may  admit  of  doubt,  of  oppofition,  and  even  of  denial.  For  thefe  reafons  I 
have  taken  the  liberty  fimply  to  pvopofe  them  as  matters  of  enquiry  j  and  only  beg  the  in- 
dulgence of  the  Academy  for  troubling  them  with  matters  that  may  not  be- attended  witl^ 
TufEcient  evidence  to  bring  convidion,  or  even  to  efcape  ccnfurc. 


POSTSCRIPT. 

THE  prefent  year  (1795)  has  been  comparatively  cold  in  its  commencement,  and  warm  in 
its  fummer  :  it  has  been  calm,  dry,  and  in  many  refpeds  a  contrail  to  the  long  ferics  of  pre- 
ceding years,  whofe  effeQs  are  regiftered  in  this  Mem.oir. 

Yet  the  extremes  of  its  temperature  have  not  been  equal  to  thofe  of  former  years,  as  fas 
*s  can  be  inferred  from  the  recorded  effecls  of  heat  and  cold  on  natural  objects.  Tho 
large  rivers  of  the  northern  province  have  not  been  bound  firmly  in  the  icy  chains  oS 
winter,  nor  have  the  grapes  ripened  in  favourable  afpe^ls  in  any  part  ef  the  kitigdom  dur- 
ing fummer,  as  formerly  occurred  in  feafons  whofe  temperature  was  denominated  extreme. 


III. 

Experiments  and  ObferiKitions  on  ElecJricity- — Excitation  —  the  two  States — Points  of  Biffereneg 
between  the  A8ion  of  -weak  andflrong  EleEiricities  compared  together.      ( W.  N.) 


Ti 


H  E  excitation  of  ele£trics  by  friQion  Hill  remains  a  myftery.  We  poffefs  nothing 
in  the  lead  refembling  a  theory  of  the  changes  of  eledlrical  capacity  which  the  rubber  and 
cylinder  undergo  during  their  charge  of  relative  pofition  in  contact.  In  the  year  1789  I 
communicated  Icveral  fafls  to  the  Royal  Society*  concerning  the  mutual  a£lion  cf  the  fillc 
flap  and  the  ele£lrical  cylinder  upon  each  other,  and  flievved  that  fomething  like  eompen- 
fation  takes  place  while  they  renjain  together.  The  tranfition  of  the  fu,rface  of  the  cylin- 
der from  the  compenfated  to  the  uncompenfated  ftate  is  ftrikingly  feen  when  a  hole  is  cut 
in  the  filk,  and  the  cylinder  turned  under  circumftances  of  confiderablc  excitation.  A  caf- 
cade  of  fire  iffucs  from  that  edge  of  the  hole  which  is  neaieft  the  culhion  ;  but  inftead  of 
being  diffipated  into  the  air,  it  bends  down  again,  and  unites  with  the  cylinder  at  the  oppo- 
fite  edge  of  the  hole,  whence  it  proceeds  as  ufual  to  the  repi^iiving  part  of  the  prime  con- 
dudor.  '      • 

The  phenomena  of  the  two  eledricitles  called  plus  and  minus  are  fingularly  diftinft  in 
almoft  every  experiment  which  can  be  made  with  the  exhibition  of  eledric  light.  Paper  is 
a  good  fubftance  for  obferving  the  vifible  paffage  of  eledricity.  If  a  ftrong  plus  eleftric 
ftrcam  be  let  fall  on  the  flat  fide  of  an  uninfulated  (heet  of  pappr,  it  forms  a  beautiful  ftar 
about  four  inches  in  diameter,  confilting  of  very  diftinft  radii  not  ramified.  The  minus 
♦Icdticlty,  in  circumftances  perfedly  fimilar,  throws  many  pointed  brufhes  to  the  paper, 

*  Plulofophical  Tranfa6tions,  No.  Jixxix. 

bat 


ether  the  Glafi  fult  of  BleHfcmiters  wtpalr  their  Effect,  431J 

but  forms  no  ftar  upon  it.    In  this  experiment  I  ufed  a  machine  with  a  cylinder  of  fevcri 
inches  diameter. 

Hence  it  fecms  to  follow,  that  a  hollow  ball  of  paper,  or  a  glafs  globe  covered  with  paper, 
•might  form  an  amufing  part  of  the  ele£lrical  apparatus  for  experiments  in  the  dark. 

The  laws  of  a£lion  with  regard  to  weak  eledlricities  and  thofe  of  confiderable  intenfitr 
appear  to  differ  in  various  particulars,  which  require  further  invefllgatlon.  Wlien  a  num- 
ber of  jars  are  charged  in  fucccflion,  that  is  to  fay,  by  infuliiting  the  whole  feries,  and 
'  caufing  the  outer  coating  of  the  fird  to  communicate  with  the  inner  of  the  fecond,  and  the 
outer  coating  of  the  fecond  with  the  inner  of  the  third,  and  fo  forth,  it  is  well  known  that 
the  whole  may  be  charged  by  communicating  eledtricity  to  the  infide  of  the  firft,  provided 
the  laft  hSve  a  communication  with  the  earth  ;  but  with  this  circumftance,  that  the  charge 
will  reftore  itfelf  by  explofion  when  the  quantity  of  electricity  is  much  lefs  than  the  firft 
jar  would  fingly  have  received  and  retained.  From  this  refult  it  has  with  fome  probabi- 
lity been  concluc'ed,  that  glafs  refills  the  communication  of  dectric  energy,  and  that  the 
jars  are  fucceffively  lefs  and  lefs  charged.  Whether  this  lall  conclufion  be  true,  has  not 
ft  believe  been  afcertained  by  experiment. 

Under  all  the  uncertainties  concerning  the  place  occupied  by  the  eleftric  charge  of 
coated  glafs,  though  it  may  feem  unfair  to  make  any  inference  refpefting  glafs  which  is 
uncoated,  yet,  upon  the  whole,  there  appears  to  be  a  probability  that  the  interpofition  of 
naked  glafs  may  impede  the  aftlon  of  eleclrlfied  bodies.  This  queftlon  more  immediately 
points  at  the  tube  In  which  the  gold-leaf  eIe£trometer  of  Bennet  is  inclofed.  To  determine 
whether  the  tube  of  the  eledrometcr  does  afFeft  the  ele£l:ric  ftate  of  the  included  leaf,  ei- 
ther by  compenfation  or  otherwife,  I  took  a  piece  of  window-glafs  eighteen  inches  long, 
two  Inches  wide,  and  one-twentieth  of  an  inch  thick,  which  I  cleaned  very  well,  and  then, 
paffed  it  feveral  times  through  the  hot  air  over  the  flame  of  a  candle.  In  this  flate  one  end 
of  the  glafs  was  laid  gently  upon  the  eledlrlfied  plate  of  Bennet's  eleftrometer,  and  thea 
fuddenly  raifed  by  a  turn  of  the  wrill.  It  was  fcarcely  poffible  to  difcern  that  the  leaves  were 
»t  all  affected ;  but  when  the  eledrometer  was  In  the  plus  flate  a  very  flight  coUapfion  was 
produced  by  raifmg  the  glafs,  and  the  contrary  effedl  was  produced  when  the  eledrometer 
was  negative.  Some  days  afterwards  the  experiment  was  repeated,  after  the  gold-leaf  had 
been  changed  for  other  pieces,  which  were  very  pointed  and  delicate  In  their  movements. 
The  refult  was,  that  the  glafs  was  always  fhewn  by  the  eleflrometer  to  be  in  a  weak  pofi- 
tive  (late  ;  and,  when  the  eleflrlcity  of  the  dc£lroraeter  wa^  made  plus,  the  collapfion  wa« 
equal  to  the  divergence  when  it  was  minus. 

In  making  thefe  experiments  I  had  previoufly  fuppofed  that  the  influence  of  the  mt- 

tallic  ftate  of  the  ele£lrometer  would  produce  fomewhat  of  the  nature  of  a  charge  upoa 

the  glafs ;  and  confequently  that  the  intenfity  of  the  leaves  would  have  been  diminlflied 

during  the  exiftence  of  that  charge  ;  and  alfo,  that  In  fuch  a  cafe  the  aftlon  of  the  metal 

through  the  glafs  would  be  fubjedl  to  the  fame  diminution  as  in  the  feries  of  jars.     But  zi 

the  glafs  did  not  appear  to  aft  in  this  manner,  it  feems  proper  to  conclude  that  clean 

glafs  does  not  afFe£t  the  eleclric  ftate  of  bodies  by  Its  vicinity,  and  that  the  divergence 

of  the  balls  or  the  gold-leaf  in  the  ele(ftrometers  of  Cavallo  and  Bennet  Is  not  diminilhed 

by  the  tube  which  furrounds  them. 

3  L  2  ^  Froirf 


440  On  EhSlrmeten  and  weo\  EkBriatteu 

From  a  variety  of  experiments  it  was  clearly  afcertained  that  the  metallic  coatingi^ 
though  by  their  vicinity  tliey  may  diminifli  the  intenfity  of  the  elcftric  ftate  in  the  leaves, 
do  neverthelefs  increafc  the  angle  of  divergence  by  their  attradion. 

When  the  goW-leaf  eleftrometer  is  made  with  a  very  fmall  tube,  its  fenfibility  is  fome« 
what  increafed  by  the  nearnefs  of  the  coatings ;  but  the  chance  of  rendering  it  unfcr- 
ticeable  from  cafual  fri6lion,  which  excites  the  glafs,  and  caufes  the  gold  leaf  to  ilick 
to  it,  together  with  the  lefs  perfe£t  view  of  the  divergence  through  a  tube  of  fmall  cur- 
Tature,  afford  reafons  why  a  diameter  of  lefs  than  an  inch  fliould  be  rejected.  Other 
reafons  of  convenience  indicate  that  the  diameter  of  the  glafs  ihould  not  much  exceed 
tiiis  quantity. 

I  was  once  induced  to  think  that  the  confiderable  magnitude  of  the  cap  of  Bennet's 
ele£l:rometer  might  render  it  lefs  capable  of  being  adled  upon  by  fmall  quantities  qf  elec- 
tricity. Experiment  did  not  however  give  much  countenance  to  this  fuppofition.  By 
trials  with  heads  of  different  fize,  the  fmalleft  were  found  to  be  rather  more  fenfible  to 
extremely  minute  eledlricities,  and  lefs  fo  to  fuch  as  were  greater.  The  influence  of  very 
weak  eleflricity  may  produce  the  oppofite  ftate  in  the  whole  of  a  fmall  head,  but  only  in 
part  of  a  larger  ;  the  remaining  part  of  this  lalt  afluming  the  oppofite  flate,  and  robbing 
the  leaves  of  part  of  their  intenfity.  But  in  higher  ele£lricities  the  whole  of  the 
large  head  may  be  urged  to  give  electricity  to  the  leaves,  in  a  quantity  which  the  fmaller 
head  could  not  give  without  acquiring  a  higher  degree  of  intenfity,  and  ccnfequently 
more  ftrongly  refifting  the  dcfired  procefs.  It  appears  therefore  that  the  maximum  of 
efFeft  with  a  given  ele£lricity,  a£ling  without  communication,  will  not  be  obtained  but 
by  an  head  of  a  definite  figure  and  magnitude. 

From  fome  experiments  of  Hoadley  and  Wiifon  with  a  number  of  prime  condudors 
feparately  infulated,  it  was  eftablifhed  that  an  eleftrified  body  brought  near  one  end  of 
fuch  a  fet  of  condudlors,  formiing  by  contact  a  right  line,  will  produce  the  contrary 
flate  in  the  nearer  conduflors,  and  the  fame  ftate  in  thofe  which  are  more  remote.  Or, 
upon  the  hypothefis  of  a  fingle  fluid,  the  electricity  of  the  body  prcfented  will  repel  that 
of  the  compound  conduftor;  fo  that  by  feparating  them  before  the  influence  is  removed,  . 
and  afterwards  examining  them,  the  refpedtive  ftates  of  the  feveral  portions  of  the  whole 
line  may  be  afcertained. 

It  was  a  conclufion  obvioufly  enough  deducible  from  this  experiment,  that  if  two  elec- 
trometers of  Bennet  were' conneiSled  by  a  metallic  bar,  there  ought  to  be  a  difference 
when  an  ele^rified  body  is  prefented  at  either  extremity,  or  at  the  middle  of  the  bar.  I 
made  this  experiment  with  a  brafs  bar  eighteen  inches  long.  Both  electrometers  were 
affecled  at  the  fame  ihftant.  Their  divergence  was  equal,  and  the  effeft  was  the  fame, 
whether  the  glafs  or  fealing-wax  was  prefented  at  either  end  or  at  the  middle  of  the  bar. 
This  refult  feems  to  indicate  a  difference  in  the  mode  of  aftion  between  the  very  weak 
«le£tricity  I  ufed  and  the  much  ftronger  of  Hoadley  and  Wiifon. 

The  adtion  of  pointed  bodies  and  of  flame  likewife  exhibits  a  remarkable  difference 
between  the  ftrong  and  the  weak  eleiSlricities.  The  prime  conduflor  of  an  elefcrical 
machine  is  very  fuddenly  deprived  of  the  greatefl  part  of  its  eleCtricity  by  the  operation 
ef  a  metallic  point  j  but  does  not  feem  to  be  much  affected  by  the  vicinity  of  burning 

candles. 


JSlf^roinetry,— Siberian  Red  Leact.       -  ^^t 

candles.  On  the  contrary,  the  eleftrometer  of  Bennet  will  fcarcely  communicate  the 
kaft  portion  of  its  eleftricity  to  a  point  not  abfolutely  in  conta£t  with  its  cap }  but  is- 
readily  deprived  of  its  eledric  ftate  by  a  candle. 

Coulomb,  by  his  method  of  torfion,  has  determined  that  the  a(^ion  of  weak  cle£lri- 
cities  diminifhes  as  the  fquare  of  the  diftance.  I  do  not  know  that  any  experiments  have 
been  made  to  determine  the  ratio  of  the  repulfion  or  attraction  of  bodies  by  eledtricity,, 
with  regard  to  the  diftance,  when  the  intenfities  are  confiderable. 

To  examine  this  obje<Et  I  caufed  a  brafs  condu£tor  to  be  made,  four  inches  in  dia- 
meter, with  a  fpherical  part  at  each  end,  of  five  inches  diameter  5  and,  on  the  whole, 
twenty  inches  long.  It  was  fixed  with  its  axis  in  the  vertical  pofition.  In  the 
upper  fpherical  part  there  was  a  flage  fupporting  a  pulley,  the  axis  of  which  ran  upon 
two  pair  of  very  delicate  friclion  wheels.  The  lower  fpherical  part  was  perforated  in  the 
axis,  to  receive  the  ftem  of  a  very  light  fphere  of  paper  gilt,  and  of  the  diameter  of 
five  inches.  Care  was  taken  that  this  ftem,  which  was  nearly  the  whole  length  of 
the  conductor  from  the  friftion  wheels  to  the  lower  orifice,  fliould  not  touch  that  orifice  j 
and  for  greater  fecurity  there  was  a  fmall  frame  carrying  three  fridtion  rollers,  againft 
one  of  which  it  was  fure  to  bear  in  cafe  of  accidental  irregularity.  The  upper  part  of  the 
ftem  was  fattened  to  a  fine  filken  thread  which  pafled  over  the  pulley,  and  was  tied  to  a 
counterpoife  adapted  by  its  figure  to  receive  fmall  weights,  in  order  that  the  equilibrium 
or  preponderance  might  be  adjufted  at  pleafure.  On  the  axis  of  the  pulley  was  an  indejt 
and  hand,  which  moved  upon  a  face  without  touching,  beneath  a  convex  glafs,  and 
(hewed  the  defcent  of  the  gilded  ball  in  inches  and  parts.  I  expected  to  have  obtained  a 
confiderable  fcale  on  my  ftem  of  twelve  inches.  But  in  the  trials  I  made  when  it  was 
finiflied,  in  which  the  afcending  power  of  the  ball  could  be  varied  at  pleafure  by  addition 
to  the  counterpoife,  I  found  either  that  it  did  not  move  at  all,  or  that,,  if  it  did,  it  ran 
with  confiderable  velocity  through  its  whole  length.  This  unexpcdted  event,  together 
with  fome  other  imperfeClions  in  the  inllrument  itfelf,  which  required  amendment  and- 
alteratiofl,  prevented  me  from  purfuing  and  diverfifying  a  courfe  of  experiment  that  pro- 
mifed  fo  little.  The  fafts  appear  however  to  ftiew,  that  in  great  intenfities  and  ihort 
diftances,  the  diminution  of  etreft,  if  it  follow  the  law  of  the  fquares  of  the  diftances,.  is 
like  the  attraction  of  the  earth  upon  projectiles,  too  fmall  to  be  perceived.  But  from  the 
indications  afibrded  by  Henley's  quadrant  eleCtrometer,  and  the  floating  eleCtrometer  of 
Nollet,  there'  appear  to  be  reafons  why  the  purfuic  ftiould  not  be  thought  unworthy  of  fur- 
ther experinasnt. 


IV. 


^nalyfis  of  the  Red  Lead  of  Siberia  %  imth  Experiments  on  the  Neiif  Metal  it  contains.     By 

Citizen  Vau^elin,    Infpeilor  of  Mines,  and  Confervator  of  Chemical  ProduEis  at  tbf 

M.ineralogical  School. 

(Concluded  from  page393,  Vol.  11.) 

Combinations  of  the  Acid  of  Red'  Lead  luith  the  Alkalis. 

X  H  E  acid  of  red  lead  forms,  in  Its  combination  with  the  alkalis,,  falts  which  arc- 
foluble,,cr]jftallifable,  and  cobured.    The  Cmpleft.  procefs  for  making  thefe  falts  confifts. 

iui 


jj.4»  ■Comh'tmtknt  efthe  Acid  ?/"Chvomei 

•Jn  boiling  upon  one  part  of  red  lead  reduced  into  fine  powder,  two  parts  of  carbonate  of 
nlkali  with  forty  parts  of  water.  By  this  means  a  double  aflinity  is  made  to  operate, 
■by  virtue  of  which  carbonate  of  lead  is  formed,  and  falls  to  the  bottom,  while  a  combina- 
tion of  thii  acid  of  red  lead  with  the  alkali  made  ufe  of  remains  fufpended  in  the  water, 
by  virtue  of  its  folubility. 

'I  he  proportion  of  alkaline  carbonate  proper  to  be  ufed  for  the  decompofitioii  of  the 
■native  red  lead  muft  vary  according  to  the  proportions  which  fubfift  between  tlie  bafes, 
the  aciiLs,  and  the  water  of  cryftallization.  The  proportions  dated  in  the  lad  paragraph 
are  fuitcd  to  the  carbonate  of  pot-afli ;  but  the  proper  quantises  in  the  other  cafes  are 
eafily  afcertained,  by  ufing  a  fmall  quantity  of  the  carbonate  at  firft,  and  afterwards 
gradually  increafing  it,  till  the  greateft  part  of  the  red  lead  is  decompofed.  On  the 
whole,  it  is  better  to  ufe  a  fmaller  thaft  too  large  a  portion  of  the  carbonate,  jn  order 
that  its  bafe  may  be  mote  completely  faturated  vv-ith  the  acid  of  the  red  lead. 

There  is  no  reafon  to  fear  a  fimilar  inconvenience  with  the  carbonate  of  ammoniac.  It 
is  proper,  on  the  contrary,  to  add  more  than  is  fufiicient  to  faturate  the  acid  of  the  red 
lead;  becaufe  a  portion  of  this  fait  will  always  be  driven  off  during  the  ebullition  which 
is  indifpenfably  nece(T\try  to  produce  the  intended  decompofition.  And  even  in  cafe  there 
fliould  remain  an  excefs  after  the  complete  decompofition  of  the  red  lead,  there  would 
be  no  danger,  becaufe  this  excefs  of  alkali  is  driven  off  by  the  evaporation  of  the  fait 
newly  formed,  and  there  is  always  a  certainty  of  obtaining  the  combination  perfedly 
pure. 

The  colour  of  the  combinations  of  the  acid  of  red  lead  with  the  alkalis  is  an  orange 
yellow  *.  Their  folutions  afford  cryftals  nearly  of  the  fame  tinge,  the  differences  being 
only  flight  variations  of  fliade.  Thefe  falts  are  decompofed  by  barytes,  lime  and  (tron- 
tian.     The  mineral  acids  likewife  decompofe  them  by  an  inverfe  operation. 

Thefe  falts  afford  oxygen  gas  by  the  adion  of  heat,  and  tbeir  refidue  has  the  appear- 
ance of  a  green  mafs.  The  ammoniacal  compound  muft  however  be  excepted,  as  its  bafe 
is  partly  decompofed  by  the  oxygen  of  the  acid,  and  leaves  in  the  retort  a  pure  green 
oxide,  the  undecompofed  portion  of  ammoniac  being  alfo  driven  off  by  the  heat. 
-  Thefe  falts  decompofe  by  double  affinity  the  calcareous,  barytic,  magnefian,  aluminous 
falts,  &c.  Mod  of  the  metallic  falts  are  likewife  decompofed  by  thefe  fubdances,  and 
afford  new  combinations  fcarcely  or  not  at  all  foluble  in  water;  and  for  the  mod  part 
red,  yellow,  orange,  or  lemon  colour. 

I  have  not  hitherto  been  able  to  determine  the  figure  of  thefe  falts  with  accuracy,  nor 
their  degree  of  folubility  in  water,  for  the  reafons  1  have  already  explained  ;  neither  have 
I  made  all  the  combinations  of  this  acid  with  the  metallic  oxides,  nor  determined  its  mode 
of  a6tion  on  the  metals.  Such  experiments  would  no  doubt  have  afforded  ir^tereding 
"phenomena  for  the  completion  of  the  hidory  of  this  metallic  acid. 

But  I  indulge  the  hope  that  thefe  experiments  are  only  retarded,  and  that  fome  fortunate 
opportunity  will  hereafter  enable  us  to  perforni  them  :  and,  at  all  events,  the  experiments 
already  made  will  be  fufficient  to  afcertain  the  prefence  of  the  acid  of  red  lead  wherever 
it  may  be  met  with,  and  didinguifli  it  from  every  other  natural  fubdance. 

*  That  of  the  ammoniacal  fait,  which  has  tlie  form  of  plated  cryftals,  is  yellow,  and  exhibits  the  metallic 
briUiancy  of  gold.    V. 

SEC 


Redu&m  and  Properties  of  the  New  Metal  Chromct  4jf3 

SECTION   VII. 

ReduStlon  of  the  Add  of  Red  Lead  to  the  Metallic  State. 

THOUGH  the  properties  of  the  acid  of  red  lead,  defcribed  in  the  foregoing  paragraphs, 
are  in  flri£lnefs  fuflicient  to  convince  thofe  who  are  in  the  habit  of  treating  metallic  fub- 
ftances,  that  this  fubftance  belongs  to  the  fame  clafs,  it  is  neverthelefs  defirable,  in  order,  as 
it  were,  to  add  the  ftamp  of  evidence  to  the  proofs  of  demonflration,  that  this  acid  ftiould 
be  reduced  to  the  metallic  ftate. 

To  obtain  this  obje£l  I  took  72  parts  of  the  acid  in  queftion,  extracted  from  the  red  lead 
by  the  muriatic  acid,  as  defcribed  in  our  fourth  fedlion,  wbicli  I  introduced  into  a  crucible- 
of  charcoal  placed  in  another  of  hard  porcelain  likewife  filled  with  charcoal  powder. 

This  apparatus,  placed  in  a  forge  furnace,  was  expofed  for  an  hour  to  the  a£tion  of  a 
very  flrong  fire  urged  by  the  blafl  of  a  (Irong  pair  of  bellows  with  three  pipes. 

Wlien  the  crucible  was  cooled  and  broken,  I  found,  to  my  great  fatisfadion,  in  the  fmall 
veflel  of  charcoal,  a  metallic  mafs  of  a  white  grey  colour,  fliining,  very  brittle,  and  upon 
the  furface  of  which  were  many  feathered  cryftals  of  the  fame  colour  pcrfedlly  metallic* 
This  metallic  mafs  weighed  forty-three  parts. 

It  appears,  from  the  refult  of  this  operation,  that  the  oxygen  does  not  adhere  with  very 
great  force  to  this  metallic  bafe,  and  that  the  acid  contains  about  0,4.0  of  its  weight  of  this 
acidifying  principle. 

SECTION   VIII. 

Properties  of  the  Metal  of  Red  Lead. 

THIS  metal,  as  I  have  already  remarked,  is  of  a  white  colour  inclining  to  grey :  It  is  very 
brittle,  and  cryftallifes  in  an  elevated  temperature  into  a  kind  of  feathered  filaments,  which, 
rife  above  the  metallic  mafs. 

The  metallic  button  being  broken,  prefented  internally  compafl  points  forming  a  clofe 
grain,  and  in  other  parts  needles  crofiing  each  other  in  all  dire£lions,  leaving  void  fpaces 
between  them,  which  prevented  me  from  determining  its  fpecific  gravity. 

A  fragment  of  this  metal  expofed  to  the  heat  of  the  blow-pipe  acquired  a  tarnifh  on  its 
furface,  and  by  continuing  the  operation  it  was  covered  with  a  light  green  cruft  ;  but  it  af- 
forded no  fign  of  fufion. 

When  heated  by  the  fame  apparatus  with  borax  it  did  not  melt,  but  was  in  a  fmall  de- 
gree diminiflied,  and  communicated  an  emerald- green  colour  to  the  fait. 

When  reduced  to  a  fine  powder,  and  treated  with  the  concentrated  boiling  nitric  acid,, 
it  was  oxided  with  much  difficulty,  and  communicated  to  the  acid  a  green  tinge  flightly. 
inclining  to  blue.  The  nitric  acid  attacks  this  metal  with  fo  much  difficulty,  that  it  wa* 
not  till  after  treating  it  repeatedly  with  conliderable  quantities  of  that  folvent  that  I  could; 
fucceed  in  diflblving  fix  grains. 

The  diflTerent  folutions  being  added  together  were  evaporated  to  drynefs.  Towards  the 
end  of  the  operation  the  refidue  aflumed  the  form  and  the  du£lility  of  a  vegetable  extraft 
of  a  red  brown  colour.  Cauftic  potafli  poured  on  this  refidue  diflblved  a  great  part,  and 
aflumed  a  lemon-yellow  colour  ;  but  part  remained  of  a  very  beautiful  green,  which  wa« 
apt  afted  upon  by  that  re-agent :  it  was  a  portion  of  the  metal  which  had  not  received. 

4  fxoiftj 


44^4  ~    On  Chemical  Denomtnathns ;  particularly  Chrome. 

from  the  nitric  acid  the  whole  quantity  of  oxygen  neceflary  for  its  acidification.    It  was 
ftill  in  the  (late  of  oxide. 

I  treated  it  again  with  the  concentrated  nitric  acid  ;  and  by  a  feries  of  operations  of  thi»- 
nature  I  at  length  fuccecded  in  completely  acidifying  it. 

The  combination  of  this  artificial  acid  with  potafli  exhibited  abfoJutely  the  fame  appear- 
ances with  the  different  re- agents  as  the  fait  which  Is  formed  with  the  natural  acid.     See. 

SeGiou  II. 

S  E  C  T  I  O  N   IX. 

Demm'ination  of  the  Metal  coiiiaitied  in  the  native  Red  Lead. 

WHEN  an  unknown  fubdance  is  to  be  examined,  the  only  method  to  afcertain  whether 
it  has  been  before  defcribed,  is  to  examine  its  properties,  and  compare  them  with  thofe  of 
other  bodies  ;  an  operation  which  fuppofes  a  knowledge  of  all  that  has  been  before  de- 
fcribed in  natural  liiftory.  And  when,  after  an  accurate  comparifon  of  the  properties  of  the 
body  under  examination  with  thofe  of  other  bodies,  it  is  found  that  none  of  thefe  laft  exhi- 
bit the  whole  of  thofe  properties,  a  fair  conclufion  may  be  formed  that  the  body  is  un- 
known, and  confequently  that  it  is  new. 

After  this  point  is  determined,  it  becomes  necefTary,  in  order  to  make  it  known  to  others 
that  its  diftinftive  charafters  {hould  be  clearly  afcertained,  and  a  name  given  to  it,  for  the 
purpofe  of  brief  defignation,  and  of  Infciiption  in  the  catalogue  of  human  knowledge. 

This  name  may  be  derived  from  various  fources ; — the  place  whence  it  was  obtained 
the  author  who  difcovered  it,  or  the  fpecific  properties  it  poflefTes,  &c. :  but  it  is  cafy  to 
fee  that  the  two  firft  fources  are  vicious.  In  fa£l,  the  name  of  the  place  feems  to  announce 
that  the  fubftance  is  to  be  found  exclufively  theie  ;  and  it  is  very  far  from  being  known, 
at  the  early  period  of  difcovery,  whether  it  may  not  be  found  elfewhere.  The  name  of  the 
author  teaches  nothing,  except  that  fuch  a  man  was  the  difcoverer  ;  a  circumdance  of  lit- 
tle intereft  to  fcience.  But  the  name  of  a  fubftance  deduced  from  its  leading  properties  is 
truly  ufeful,  becaufe  it  brings  to  mind,  and  in  fome  meafure  places  the  object  before  th« 
eyes  by  a  faithful  (ketch  of  its  attributes. 

From  thefe  confiderations  I  have  thought  fit  to  adopt  the  name  chrome,  which  was  pro- 
pofed  to  me  by  Cit.  Haiiy,  to  defignate  the  new  metal  found  in  the  native  red  lead.  Iq 
truth,  this  name  does  not  perfeftly  agree  with  the  complete  metal,  becaufe  it  has  no  vert 
diftinft  colour;  and  becaufe,  even  if  it  had  one,  this  would  not  be  a  fulhcient  reafon,  Cnce 
every  metal  has  a  more  or  lefs  peculiar  colour. 

But  it  agrees  wonderfully  well  with  its  combinations  with  oxygen,  which  afford  a  green 
oxide,  or  a  red  acid,  according  to  the  proportions  of  that  principle,  and  becaufe  each  of  its 
primary  combinations  communicates  its  colour  to  all  the  fecondary  combinations  into  which 
it  enters;  properties  which  belong  to  it  almoft  exclufively. 

This  name  appears  to  me  to  be  fo  much  the  better  founded,  as  this  fubftance  has  not 
yet  been  difcovered  except  in  the  (late  of  acid  or  oxide,  and  becaufe  it  may  perhaps  never 
.be  found  in  the  native  metallic  ftate. 

Neverthelefs,  as  I  am  not  difpofedto  confider  the  adoption  of  one  name  rather  than  an- 
other as  of  any  importance,  provided  the  name  do  exprefs  fome  remarkable  or  diftimaive 
property  of  that  which  it  denotes,  I  (ball  with  pleafure,  if  a  better  name  be  found,  confent 
to  fubftitute  it  inftead  of  chrome. 

$  E  C. 


Pkihfophkal  and  Ecofism'ical  Vfes  o/Cktomt,-  445- 

S  E  C  T  I  O  N   X. 

JJfes  of  Chrome,  of  the  Oxide  of  Chrome,  and  of  the  Chromic  Acid, 

THE  brittlenefs  of  chrome,  its  refiftance  to  the  aftion  of  fire,  and  the  fmall  mafles  In 
which  it  has  hitherto  been  found,  afford  little  expedlation  that  this  metal  will  ever  be  of 
great  ufe  in  the  arts.  But  this  afTertion  may  be  too  ftrong ;  for  a  new  fubftance,  of  which 
the  properties  at  firft  appear  to  be  of  fmall  intereft  to  fociety,  is  fometimes  found,  in  the 
fubfequent  procefles  of  inveftigation,  to  be  capable  of  very  important  applications  in  the 
irts  and  fciences. 

The  acid  and  the  oxide  of  this  metal  are  certainly  not  fubje£l  to  the  fame  obferwitlon. 
The  former,  by  the  beautiful  emerald-green  which  it  communicates  even  to  enamels,  with- 
out being  fubjc£t  to  alteration  in  the  purity  of  its  ftiade,  will  afford  to  painters  and  enamel- 
lers  an  additional  object  to  enrich  their  produftions,  and  add  to  the  perfecSlion  of  their  art  : 
the  fecond,  by  the  beautiful  cinnabar  red  which  it  alTumes  and  keeps  in  its  combination 
Vith  mercury  ;  the  orange-red  colour  it  affords  with  lead  ;  the  carmelite  red  it  communi- 
cates to  filver,  may  become  highly  valuable  for  paintings  in  oil  and  water-colours. 

Chemiftry  will  be  greatly  benefited  by  this  excellent  re-agent  to  dete£l:  the  fmalleft 
quantities  of  mercury,  filver,  and  lead,  diffolved  in  acids  by  the  different  colours  it  pro- 
duces when  its  adlion  is  afllfted  by  an  alkali.  And,  in  the  fame  manner  as  this  acid  indi- 
cates the  prefence  of  the  metals  here  fpoken  of,  thofe  metals  in  their  turn  may  ferve  to  dif- 
cover  the  chromic  acid,  if  it  be  previoufly  put  into  the  neceffary  condition  to  produce  the 
before -mentioned  effects. 

If  the  chromic  acid  fliould  hereafter  be  abundantly  found  In  any  other  combination  be- 
Cdes  that  of  lead,  it  might,  after  extra£tion  by  carbonate  of  potafli,  be  ufed  for  the  artificial 
compofition  of  red  lead,  and  furnifh,  in  abundance,  this  valuable  orange-red  colour  for 
painters'  ufe,  which  is  fold  very  dear  in  Siberia,  and  applied  to  this  purpofe  with  great  fuc- 
cefs.  For  thisobjeiSt  the  native  red  lead,  which  is  diffeminated  in  fmall  cryftals,  or  plates, 
in  the  fiffures  of  quartzofe  or  gritftone  gangues,  in  which  it  is  commonly  found,  might  be' 
pulverized,  then  boiled  with  a  folution  of  carbonate  of  potafli,  and  mixed  with  nitrate  of 
lead  ;  the  acid  of  which  will  faturate  the  potalh,  and  afford  its  metal  to  the  new  acid,  which 
will  thus  produce  a  colour  no  lefs  beautiful  than  the  natural,  and  perfcdtly  clear  of  the 
matrix. 

There  is  reafon  to  prefume  that  chrome,  cither  In  the  ftate  of  oxide  or  of  acid,  will  be 
found  fingly  or  engaged  in  fomc  other  combinations.  For  tlie  analyfis  of  the  emerald  of 
Peru  has  already  fliewn  me  that  its  colouring  part  Is  afforded  by  the  oxide  of  this  metal ;  » 
circumftance  which  gives  the  moft  agreeable  proof  of  the  goodnefs  and  fixity  of  this  colour, 
as  it  is  known  that  the  emerald  can  fuftain  the  moft  violent  degree  of  heat  without  lofing 
Its  colour. 

.  I  have  likewife  found  that  the  yellowilh  green  tufted  cryftals,  which  often  accompany  the 
rod  lead  ore  of  Siberia,  are'fotmed  of  chrome  and  lead,  both  united,  in  the  ftate  of  oxide. 
Green  cryftals  poffeffing  the  fame  form,  the  fame  dimenfions,  and  the  fame  fituations  on 
the  matrix  as  thofe  of  red  lead,  but  which  are  a  combination  of  the  oxides  of  chrome  and 
<jf  lead,  are  likewife  found  in  certain  fpecimens  of  the  native  red  lead.  It  is  probable  that 
tluefe  combinations  originally  exifted  in  the  ftate  of  chromatc  of  lead,  and  that  in  procefs- 
y«t.  11.— Jan.  1793.  -  3  M  mi 


446  Defcr'iptton  of  an  Apparatus  fot 

of  time  a  portion  of  oxygen  having  been  carried  off  by  unknown  caufes,  converted  tliem  t# 
the  ftate  of  oxide,  and  changed  the  red  colour  to  green. 

From  paragraph  III.  it  follows  that  the  Siberian  red  lead  contains 

By  aoalyCs.  Experiment  V,      Byfynthefis,  EiperimentVI. 
Oxide  of  lead  -  -        63,96  65,12 

Chromic  acid  -  -         36,40  34}88 


Exper'tmsnts  to  determine  the  Denfty  of  the  Earth.     By  HenRT  CAFENDISHy  Efp 

F.R.S.  andA.S* 


M. 


.  A  N  Y  years  ago  the  Rev.  John  Michell,  F.  R.  S.  contrived  a  method  of  determining 
the  denfity  of  the  earth,  by  rendering  fenfible  the  attra£llon  of  fmall  quantities  of  mat- 
ter J  but,  as  he  was  engaged  in  other  purfuits,  he  did  not  complete  the  apparatus  till  * 
Ihort  time  before  his  death,  and  did  not  live  to  make  any  experiments  with  it.  After  hi» 
death  the  apparatus  came  to  the  Rev.  Francis  John  Hyde  Wollafton,  Jackfonian  profeflbr 
at  Cambridge,  who,  not  having  conveniences  for  making  experiments  with  it  in  the  man- 
ner he  could  wifh,  prefented  it  to  Mr.  Cavendifh. 

The  apparatus  is  very  (imple :  it  confifts  of  a  wooden  arm  fix  feet  long,  made  fo  as  to- 
unite  great  ftrength  with  little  weight.  This  arm  is  fufpended  in  an  horizontal  pofition  by 
a  flendcr  wire  forty  inches  long,  and  to  each  extremity  is  hung  a  leaden  ball  about  two 
inches  in  diameter ;  and  the  whole  is  inclofed  in  a  narrow  wooden  cafe,  to  defend  it  from 
the  wind. 

As  no  more  force  is  required  to  make  this  arm  turn  round  on  its  centre  than  is  neceflary 
to  twift  the  fufpending  wire,  it  is  plain  that,  if  the  wire  is  fufficiently  flender,  the  mod  mi- 
nute force,  fuch  as  the  attra£lion  of  a  leaden  weight  a  few  inches  in  diameter,  will  be 
fufficient  to  draw  the  arm  fenfibly  afide.  The  weights  which  Mr.  Michell  intended  to- 
ufe  were  eight  inches  diameter.  One  of  thefe  was  to  be  placed  on  one  fide  of  the  cafe,, 
oppofite  to- one  of  the  balls,  and  as  near  it  as  could  conveniently  be  done,  and  the  other  on 
the  other  fide,  oppofite  to  the  other  ball,  fo  that  the  attradlion  of  both  thefe  weights  would 
confpire  in  drawing  the  arm  afide  ;  and  when  its  pofition,  as  affeded  by  thefe  weights,  was 
afcertained,  the  weights  were  to  be  removed  to  the  other  fide  of  the  cafe,  fo  as  to  draw  the 
arm  the  contrary  way,  and  the  pofition  of  the  arm  was  to  be  again  determined  ;  and  confe- 
quently  half  the  difference  of  thefe  pofitions  would  fhew  how  much  the  arm  was  drawn.- 
afide  by  the  attraflion  of  the  weights. 

In  order  to  determine  from  hence  the  denfity  of  the  earth,  it  is  neceffary  to  afcertain: 
what  force  is  required  to  draw  the  arm  afide  through  a  given  fpace.  This  Mr.  Michell 
intended  to  do  by  putting  the  arm  in  motion,  and  obferving  the  time  of  its  vibrations,  from, 
which  it  may  be  eafily  computed-f-.  ' 

•  Abridgment  of  his  paper  in  the  Philofophical  Tranfaftions^  1798,  p.  469. 

t  Mr.  Coulomb  has  in  a  variety  of  cafes  ufed  a  contrivance  of  this  kind  for  trying  fmall  attraftions  ;  but  Mr. 
Michell  informed  Mr.  C.  of  his  intention  of  making  this  experiment,  apd  of  the  method  he  intended  to  ufe,  be. 
fere  the  publication  of  acy  of  Mr.  Coulomb's  experiments. 

6.  Mr; 


ttieafuriiig  the  mutual  Gravitation  of  Bodies.  447 

Mr.  Michell  had  prepared  two  wooden  ftands,  on  which  the  leaden  weights  were  to  be 
■fupported  and  puflied  forwards  till  they  came  almoft  in  contaft  with  the  cafe  ;  but  he  ftems 
to  have  intended  to  move  them  by  hand. 

As  the  force  with  which  the  balls  are  attradled  by  thefe  weights  is  cxcefilvely  minute,  not 
more  than  one  fifty-millionth  part  of  their  weight,  It  is  plain  that  a  very  minute  difturbing  force 
■will  be  fufficient  to  deftroy  the  fuccefs  of  rhe  experiment :  and  from  the  following  experi- 
ments it  will  appear,  that  the  difturbing  force  moft  difficult  to  guard  againfl  is  that  arifing 
from  the  variations  of  heat  and  cold  ;  for,  if  one  fide  of  the  cafe  is  warmer  than  the  other,  the 
air  in  conta£l  with  it  will  be  rarefied,  and  in  confequence  will  afcend,  while  that  on  the 
other  fide  will  defcend,  and  produce  a  current  which  will  draw  the  arm  fenfibly  afide  *. 

As  Mr.  Cavendifh  v/as  convinced  of  the  neceffity  of  guar^ling  againfl;  this  fource  of  er- 
ror, he  refolved  to  place  the  apparatus  in  a  room  which  (hould  remain  conftantly  fliut,  and 
to  obferve  the  motion  of  the  arm  from  without  by  means  of  a  telefcope,  and  to  fufpend  the 
leaden  weights  in  fuch  a  manner  that  he  could  move  them  witliout  entering  into  the  room. 
This  difference  in  the  manner  of  obferving  rendered  it  neceflary  to  make  fome  alteration  in 
Mr.  Michell's  apparatus :  and  as  there  were  fome  parts  of  it  which  Mr.  Cavendifli  thought 
not  fo  convenient  as  could  be  wlftied,  he  chofe  to  make  the  greateft  part  of  it  afreflr. 

Plate  XIX.  is  a  longitudinal  vertical  fe£lion  through  the  inftrument,  and  the  building  in 

•which  it  is  placed.     ABCDDCBAEFFE  is  the  cafe,  x  and  x  are  two  balls  wliich 

are  fufpended  by  the  wires  h  x  from  the  arm  gh  mh,  which  is  itfelf  fufpended  by  the  flen- 

der  wire  gl.    This  arm  confifts  of  a  flender  deal  rod  h  m  h,  ftrengthened  by  a  filver  wire 

.hgh\  by  which  means  it  is  made  ftrong  enough  to  fupport  the  balls,  though  very  light  f. 

The  cafe  is  fupported  and  fet  horizontal  by  four  fcrews,  refting  on  pofts  fixed  firmly  into 
the  ground  :  two  of  them  are  reprefented  in  the  figure  by  S  and  S  ;  the  two  others  are  not 
reprefented,  to  avoid  confufion.  G  G  and  G  G  are  the  end  walls  of  the  building.  W 
and  W  arc  the  leaden  weights  which  are  fufpended  by  the  copper  rods  Rr  PrR  and  the 
wooden  bar  r  r  from  the  centre  pin  ?/>.  This  pin  pafTes  through  a  hole  in  the  beam  H  H, 
perpendicularly  over  the  centre  of  the  inftrument,  and  turns  round  in  it,  being  prevented 
from  falling  by  the  plate />.  M  M  is  a  pulley  faftened  to  this  pin,  and  M/«  a  cord  wound 
round  the  pulley  and  paffing  through  the  end  wall,  by  which  the  obferver  may  turn  it 
round,  and  thereby  move  the  weights  from  one  fituation  to  the  other.  When  the  weights 
are  in  the  poGtion  reprefented  in  the  engraving,  both  confpire,  by  their  adlion  on  the  fmall 
weights  X  Xy  to  draw  the  arm  in  the  fame  direftion ;  but  when,  by  means  of  the  pulley 

*  Mr.  Caffini,  in  obferving  the  variation-compafs  placed  by  him  in  the  Obfervatory  (which  was  conftrufled 
fo  as  to  make  very  minute  changes  of  pofitiou  vifible,  and  in  which  the  needle  was  fufpended  by  a  filk  thread), 
found  that  ftanding  near  the  box,  in  order  to  obferve,  drew  the  needle  fenfibly  afide  ;  which  I  have  no  doubt 
was  caufed  by  this  current  of  air.  It  muft  be  obfer\'ed  that  his  compafs-box  was  of  metal,  which  tranfmits  heat 
fafter  than  wood,  and  alfo  was  many  inches  deep ;  both  which  caufes  ferved  to  increafe  the  current  of  air.  To 
tJiminifli  the  tifefl  of  this  current,  it  is  by  all  treans  advifable  to  make  the  box  in  which  the  needle  plays  no» 
much  deeper  than  is  neceflary  to  prevent  the  needle  from  ftriking  againft  the  top  and  bottom.     C. 

f  Mr.  Michell's  rod  was  entirely  of  wood,  and  was  much  ftronger  and  ftitfer  than  this,  though  not  much 
tieavier ;  but  as  it  had  warped  when  it  came  to  Mr.  Cavendifli,  he  chofe  to  make  another,  and  preferred  this 
form,  partly  as  being  eafier  to  conflruft  and  meeting  with  lefs  refiftance  from  the  air,  and  partly  becaufe,  from 
its  being  of  a  left  complicated  form,  he  could  more  eafily  compute  how  much  it  was  attrafted  by  the  weights. 

3  M  2  MM, 


44^  jbefcr'iptktt  of  an  Apparatus,  a>i3 

MM,  the  obfervcf  caufes  them  to  move  through  a  confiderable  portion  of  a  femlcircle,  they 
will  arrive  at  a  fccond  pofition,  in  which  their  joint  a£lion  will  move  the  arm  in  the  con-, 
trary  direclion.  Thefe  weights  are  prevented  from  ftrikiiig  the  inftrument  by  pieces  of 
wood  faftened  to  the  wall  of  the  building. 

-  The  filuation  of  the  arm  is  determined  by  flips  of  ivory  placed  within  the  cafe  near  each 
extremity  of  the  arm.  Thefe  flips  bear  a  fet  of  divifions  of  the  inch  into  twenty  parts,  to 
which  a  fmall  ftip  at  each  end  of  the  arm  applies,  without  contact,  a  vernier  that  affords  a 
fubdivifion  into  hundredth  parts.  Eflimation  by  the  eye  looliing  through  the  fhort  telefcopes 
T  and  T,  gives-  the  pofition  of  the  arm  to  (till  greater  nicety.  The  lamps  L  and  L  throvf 
light  on  tlie  divifions  by  convex  glafles,  and  no  other  light  is  admitted  into  the  room. 

t"  K  is  a  wooden  rod,  which,  by  means  of  an  endlefs  fcrcw,  turns  round  the  fupport  to 
which  the  wire  ^  /  is  faftened,  and  thereby  enables  the  obferver  to  turn  round  the  wire  tiU< 
the  arm  fettles  in  the  middle  of  the  cafe  without  danger  of  touching  either  fide.  The  wire 
g  L'li  fattened  to  its  fupport  at  top,  and  to  the  centre  of  the  arni  at  bottom,  by  brafs  dips,  ia 
which  it  is  pinched  by  fctews.  The  different  parts  are  drawn  nearly  in  the  proper  propor- 
tion to  each  other. 

Suppcfe  the  arm  to  be  at  reft  and  its  pofition  to  be  obferved,  let  the  weights  be  thea 
moved  ;  the  arm  wi!  not  only  be  drawn  afide  thereby,  but  It  will  be  made  to  vibrate,  and 
its  vibrations  will  continue  a  great  while  ;  fo  that,  in  order  to  determine  how  much  the  arm 
is  drawn  afide,  it  is  necefiary  to  obferve  the  extreme  points  of  the  vibrations,  and  from 
thence  to  determine  the  point  which  it  would  reft  at  if  its  motion  were  deftroycd,  or  the 
point  of  reft.  To  do  this,  Mr.  Cavendilh  obferves  three  fucceffive  extreme  points  of  vibra- 
tion, and  takes  the  mean  between  the  firft  and  third  of  thefe  points  as  the  extreme  point 
of  vibration  in  one  direclion,  and  then  affumes  the  mean  between  this  and  the  fecond  ex- 
treme as  the  point  of  reft;  for,  as  the  vibrations  are  continually  diminiftiing,  it  is  evident 
that  the  mean  between  two  extreme  points  will  not  give  the  true  point  of  reft. 

It  may,  he  adds,  be  thought  more  exa6l  to  obferve  many  extreme  points  of  vibration, 
fb  as  to  find  the  point  of  reft  by  different  fets  of  three  extremes,  and  to  take  the  mean  re- 
fult;  but  it  muft  be  cbferved,  that,  notwithftanding  the  pains  taken  to  prevent  any  dif- 
turbing  force,  the  arm  will  feldom  remain  perfeflly  at  reft  for  an  hour  together ;  for  which 
teafon  it  is  beft  to  determine  the  point  of  reft  from  obfervations  made  as  foon  after  the  mo- 
tion of  the  weights  as  poffible. 

The  next  thing  to  be  determined  is  the  time  of  vibration,  which  he  finds  in  this  man- 
ner :  He  obferves  the  two  extreme  points  of  a  vibration,  and  alfo  the  times  at  which  the 
arm  arrives  at  two  given  divifions  between  thefe  extremes,  taking  care,  as  well  as  he  can 
guefs,  that  thefe  divifions  ftiallbe  on  different  fides  of  the  middle  point,  and  not  very  far 
from  it.  He  then  completes  the  middle  point  of  the  vibration,  and  by  proportion  finds  the 
time  at  which  the  arm  comes  to  this  middle  point.  He  then,  after  a  number  of  vibrations,, 
repeats  this  operation,  and  divides  the  interval  of  time  betweenthe  coming  of  the  arm  to 
thefe  two  middle  points  by  the  number  of  vibrations,  which  gives  the  time  of  one  vibra- 
tion.    The  propriety  of  this  method  is  more  fully  explained  in  the  Memoir  itfelf. 

In  Mr.  Cavendifti's  firft  experiments  the  wire  by  which  the  arm  was  fuf^ended  was  39^- 
inches  long.  It  was  of  copper  filvered,  one  foot  of  which  weighed  a/^ths  grains ;  and  its 
ftiffhefs  was  fuch  as  to  make  the  arm  perforraone  vibration  in  about  15  minutes.    It  was 

imraediatel}r. 


Experiments  oh  the  tnutual  Gravitaikn  ef  Sod'ifi,  4a|^ 

immediately  found  that  it  was  not  ftiff  enough,  as  the  attrafllon  of  the  wefghts  drew  the  balW 
fo  much  afid'e  as  to  make  them  touch  the  fides  of  the  cafe.  It  was  thought  proper,  how* 
erer,  to  make  fome  experiments  before  a  ftifFer  wire  was  fubflituted  in  its  place. 

In  this  trial  the  rods  by  which  the  leaden  weights  were  fufpended  were  of  iron,  the  pro- 
bability of  magnetlfm  in  which  feemed  to  be  of  no  confequence,  as  the  arm  contained  no- 
thing magnetical.  Some  trials  however,  for  greater  fecurity,  were  maJe  with  the  rods 
alone.  Tlie  efFe£t  was  fuch  as  might  juRify  a  very  flight  fufpicion  of  magnetifm ;  for  which 
xeafon  the  rods  were  changed  for  others  of  copper.  "When  the  weights  were  hung  on,  the 
•ttraction  on  the  ball  was  very  fenfible,  as  it  carried  the  latter  through  fifteen  divifions,  or 
if  inch;  and  the  regularity  of  the  refults  was  fuch,  that  the  extremes  did  not  differ  from 
each  other  more  than  one-tenth  part.  It  was  found  that  the  effe£l  of  the  attra£tion  feemed  • 
to  incrcafe  for  half  an  hour  or  an  hour  after  the  motion  of  the  weights  ;  an  effeft  which 
might  be  fuppofed  to  arife  from  a  want  of  clafticlty,  either  in  the  fufpended  wire  or  fome- 
thing  it  was  faftened  to,  which  might  make  it  yield  more  to  a  given  preflure,  after  a  long 
continuance  of  that  preffure,  than  it  did  at  firft.  This  fufpicion  was  put  to  the  trial  by 
keeping  the  wire  for  two  or  three  hours  in  a  ftate  of  torfion  amounting  to  fifteen  divifions, 
and  then  returning  it  by  means  of  the  handle  K  to  its  original  fituation.  It  was  not  found 
by  two  repetitions  of  the  experiment  that  the  wire  had  acquired  any  fet  or  permanent  twift. 
The  arm  was  then  fufpended  by  a  differ  wire,  with  which  the  apparatus,  inftead  of  perform- 
ing its  vibration  in  about  fifteen  minutes,  employed  only  feven.  The  motion  of  the  arm 
was  in  this  cafe  not  quite  fix  divifions  between  the  two  oppofite  pofitions  of  the  weights,. or 
the  deviation  from  the  natural  ftation  of  the  arm  was  half  that  quantity. 

A  variation  of  the  power  of  the  weights  upon  the  balls,  in  fome  refpedt  fimilar  to  that 
obferved  with  the  fmall  wire,  was  alfo  found  to  take  place  in  the  prefent  experiments.  It 
happened  that  the  cafe  in  which  the  arm  was  enclofed  was  placed  nearly  parallel  to  the 
magnetic  eaft  and  well ;  and  therefore,  if  there  was  any  thing  magnetic  in  the  balls  and 
weights,  the  balls  would  acquire  polarity  from  the  earth — and  the  weights  alfo,  after  re- 
maining for  fome  time  in  either  of  the  near  pofitions,  would  acquire  a  polarity  of  the  fame, 
kind,  and  attraft  the  balls  more  ftrongly  on  that  account;  and  on  the  contrary,  when  re- 
moved to  the  oppofite  near  pofition,  if  the  magnetifm  continued  permanent  in  the  weights 
for  fufficient  time,  the  magnetic  power  would  operate  in  the  way  of  repulfion.  This  was 
in  fad  the  kind  of  effe£l  pointed  out  by  the  obfervations.  The  accurate  habits  which  fo 
eminently  diftinguifh  all  the  experimental  proceffes  of  Mr.  Cavendifli  did  not  however  per- 
mit him  to  reft  contented  with  the  indu£lion  to  which  thefe  fafts  feemed  to  point.  He  al- 
tered his  apparatus  fo  as  to  produce  at  pleafure  a  rotation  in  the  weights  upon  their  vertical 
axes,  without  opening  the  room  or  difturbing  their  actual  fituation.  By  this  contrivance  he 
had  it  in  his  power  to  difpofe  the  imaginary  magnetic  poles  in  fuch  pofitions  as  were  beft 
calculated  to  deteft  their  operation.  The  arm  was  not  affected;  and  confequently  it  fol- 
lows that  the  irregularity  in  queftion  did  not  arife  from  magnetifm.  This  canclulion  was 
ftill  more  firmly  eftablilhed  by  fubftituting  two  aflual  magnetic  bars  in  the  place  of  the 
weights ;  for  it  was  not  obferved  that  any  alteration  was  produced  by  reverfing  the  pofitioai 
of  their  poles. 

The  next  circumftance  that  fuggefted  itfelf  was,  that  the  effeft  might  be  owing  to  a  dif- 
ference of  temperature  between  the  weights  and  the  cafe  i  for  it  is  evident,  that  if  the 

'  weights 


4  Jo  Experiments  to  determine  tie  Denftty  of  the  Earth. 

^weights  were  much  warmer  than  the  cafe,  they  would  warm  that  fide  which  was  next  to 
them,  and  produce  an  afcending  current  of  air,  which  v/ould  be  accompanied  by  a  defcend- 
ing  current  towards  the  oppofite  fide,  and  two  horizontal  currents  near  the  top  and  bot- 
tom ;  the  latter  of  which  would  impel  the  ball  towards  the  weight.  Though  it  feemed 
fcarcely  probable  that  the  weights  fhould  happen  to  be  wai^mer  than  the  cafe,  and  that  in 
a  fufficicnt  degree  to  afford  any  perceptible  confequence,  our  author  neverthelefs  deter- 
mined to  fubmit  the  matter  to  examination.  He  therefore  placed  two  lamps  under  the 
weights  while  in  the  mid-way  pofition,  and  placed  a  thermometer  with  its  bail  clofe  to  the 
outfide  of  the  cafe,  near  that  part  which  one  of  the  weights  would  approach  when  brought 
into  the  pofition  to  exert  its  attraftion  upon  the  ball.  The  door  of  the  room  was  then 
fliut,  and  fome  time  afterwards  the  weights  were  moved  to  this  lad- mentioned  pofition. 
At  firft  the  arm  was  drawn  afide  only  in  its  ufual  manner;  but  in  half  an  hour  the  effedt 
was  fo  much  increafed  that  the  arm  was  drawn  fourteen  divifions  afide  inftead  of  about 
three,  as  it  would  ocherwife  have  been  ;  and  the  thermometer  was  raifed  near  i|-  °,  namely 
from  61°  to  624  °.  On  opening  the  door,  the  weights  were  found  to  be  no  more  heated 
than  juft  to  prevent  their  feehng  cool  to  the  hand. 

From  the  great  effeft  of  a  difference  of  temperature  it  became  dcfirable  to  afcertain  the 
temperature  of  the  weight  itfelf,  and  of  the  air  near  the  cafe,  in  the  fubfequent  experiments. 
A  fmall  thermometer  was  therefore  inferted  in  one  of  the  balls,  and  another  placed  clofe  to 
the  cafe.  A  number  of  experiments  were  then  made,  in  which  the  differences  of  tem- 
perature between  the  weights  and  the  external  air  were  obferved  ;  the  weights  being  in 
fome  inRances  heated  by  a  lamp,  and  in  others  cooled  by  means  of  ice.  It  was  found 
that  a  higher  temperature.in  the  weight  occafioned  a  greater  deviation  or  apparent  attrac- 
tion of  the  ball  j  and,  on  the  contrary,  that  a  lower  temperature  caufed  the  ball  to  be 
driven  by  a  current  in  the  oppofite  dire£l:ion. 

After  this  minute  and  fcientific  inveftigation  of  the  caufes  which  are  capable  of  pro- 
ducing error  in  the  refults,  Mr.  Cavendifli  proceeded  to  make  his  fundamental  experiments. 
Thefe  are  tabulated  at  length  in  the  memoir  itfelf,  and  followed  by  a  detail  of  the  method 
of  computing  the  denfity  of  the  earth.  The  firft  thing  to  be  done  is  to  determine  from 
the  time  of  a  vibration,  what  force  is  required  to  draw  the  arm  afide  ;  and  the  next,  to 
find  the  proportion  which  the  attraftion  of  the  weight  upon  the  ball  bears  to  that  of  the 
earth  upon  the  fame  ball,  fuppofing  the  ball  to  be  placed  in  the  middle  of  the  cafe  :  and  from 
thefe  refults  (fince  the  diameter  and  fpecific  gravity  of  the  weights  and  balls  compared  with 
water,  and  the  diameter  of  the  earth,  are  alfo  known ;  together  with  the  fads  that  the 
quantities  of  matter  are  as  the  attraiftive  forces  at  like  diftances,  and  vary  in  the  inverfc 
duplicate  ratio  of  the  diftance)  the  mean  denfity  of  the  earth  itfelf  may  alfo  be  found. 
Several  corrections  requifite  to  be  made  in  this  denfity  are  then  ftated ;  namely,  on  ac- 
count of  the  refiftance  of  the  arm  to  motion,  the  attraftion  of  the  weights  on  the  arm, 
and  on  the  remote  ball;  the  attra£lion  of  the  copper  rods,  and  of  the  cafe  itfelf;  and  for 
the  alteration  of  the  attraction  of  the  weights  upon  the  balls  according  to  the  pofition  of 
the  arm  ;  which  laft  is  of  more  Cgnification  than  all  the  reft.  For  all  which  I  mull,  for 
the  fake  of  brevity,  refer  to  the  TranfaCtions. 


57.'* 


r  451  J 


The  foUoivhig  TAB L  E  contains  the  Refults.ofthe  Experiments, 


Experiment 

Mot.  weight. 

Mot.  arm. 

Do.  corr. 

Time  vibr. 

Do.  corr. 

Denfity. 

,  r 

m  to  + 

M>32 

»3.42 

/    It 

5.5 

'l 

+  to  m 

14,1 

I3.'7 

14.55 

5,61 

2.  / 

m  to  + 

i5>87 

14,69 

4,88 

1 

+  to  m 

^5>i5 

14,14 

14,42 

5.07 

y{ 

+  to  m 
m  to  + 

15,22 

13^56 
13.28 

14.39 
14.54 

5.26 
5.55 

f 

m  to  + 

3.*i 

2,95 

6,54 

5.36 

4.  J 

+  to  — 

6,i8 

7.1 

5.29 

I 

—  to  + 

S>9^ 

7.3 

5,58 

^•{ 

+  to  — 
— to  + 

5.9 

5,98 

7.5 
7.5 

5.65 

5.57 

H 

m  to  — 
—  to  + 

3.03 
5.9 

2.9 

5)71 

5.53 
5,62 

^•{ 

m  to  — 
—  to  + 

3.^5 
6,1 

3.03 
5.9 

by  mean. 

6.57 

5.29 
5.44 

8./ 

m  to  — 

3.13 

3.00 

5.34 

I 

—  to  + 

5.72 

S.54 

' 

5.79 

9- 

+  to  — 

6.32 

6,58 

5.1 

10. 

+  to  — 

6,15 

6.59 

5.27 

II. 

^-  to— 

6,07 

7.1 

5.39 

12. 

—  to  + 

6,09 



7.3 

5.42 

.3.{ 

—  to  + 

6,12 

7.6 

5.47 

+  to  — 

5,97 

7.7 

5.63 

M.     1 

—  to  + 

6,27 



7.6 

5.34 

I 

+  to  — 

6,13 

7.6 

5.46 

»5- 

-to  + 

6.34 

7.7 

5.3 

16. 

—  to  + 

6,1 

7,16 

5.75 

•H 

—  to  4- 
+  to  — 

5>78 
5.64 

7.2 

7.3 

5.68 
5.85 

In  the  fecond  column  the  letter  m  denotes  the  middle  poCtion  of  the  weights  when 
each  is  equidiftant  from  the  bails,  +  denotes  one  of  the  near  pofitions,  and  —  the  oppo- 
fite  near  pofiiion. 

1  copy 


0it    '  Experiments  to  detertitiiie  tfie  Denfit^  of  the  Earth 

I  copy  Mr.  Cavendifh's  concluding  remarks  in  his  own  words : 

"  From  this  table  it  appears,  that  though  the  experiments  agree  pretty  Well  together, 
f^t  the  difference  between  them  both  in  the  quantity  of  motion  of  the  arm  and  In  the  time 
di  vibration  is  greater  than  can  proceed  merely  from  the  error  of  obfervation.  As 
to  the  difference  in  the  motion  of  the  arm,  it  may  very  well  be  accounted  for  from  the  cur- 
rent of  air  produced  by  the  difference  of  temperature  ;  but  whether  this  can  account  for 
the  difference  in  the  time  of  vibration  is  doubtful.  If  the  current  of  air  vns  regular,  and  of 
the  fame  fwiftnefs  in  all  parts  of  the  vibration  of  the  ball,  I  think  it  could  not  -,  but  as  there 
will  mod  likely  be  much  irregularity  in  the  current,  it  may  very  likely  be  fuflicient  to  ac- 
count for  the  difference. 

"  By  a  mean  of  the  experiments  made  with  the  wire  firfl.  ufed,  the  denfity  of  the  earth 
comes  out  5,48  times  greater  than  that  of  water;  and.by  a  mean  of  thofe  made  with  the 
latter  wire  it  comes  out  the  fame ;  and  the  extreme  difference  of  the  refults  of  the  twenty- 
three  obfervations  made  with  this  wire  is  only  ,75 ;  fo  that  the  extreme  refults  do  not  dif- 
fer from  the  mean  by  more  than  ,38,  or  -^-th  of  the  whole,  apd  therefore  the  denfity  fhould 
feem  to  be  determined  hereby  to  great  exadlnefs.  It  indeed  may  be  obje£led,  that  as  the 
refult  appears  to  be  influenced  by  the  current  of  air  or  fomc  other  caufe,  the  laws  of  which 
we  are  not  well  acquainted  with,  this  caufe  may  perhaps  aft  always  or  commonly  in  the 
Came  direftion,  and  thereby  make  a  confiderable  error  in  the  refult.  But  yet,  as  the  ex- 
periments were  tried  in  various  weathers  and  with  confiderable  variety  in  the  difference  of 
temperature  of  the  weights  and  air,  and  with  the  arm  refting  at  different  diftances  from  the 
Cdes  of  the  cafe,  it  feenis  very  unlikely  that  this  caufe  fkould  adt  fo  uniformly  in  the  fam» 
^ay  as  to  make  the  error  of  the  mean  refult  nearly  equal  to  the  difference  between  this 
tnd  the  extreme  ;  and  therefore  it  feems  very  unlikely  that  the  denfity  of  the  earth  {hould 
differ  from  5,48  by  fo  much  as  -jVth  of  the  whole. 

"  Another  obje£tion  perhaps  may  be  made  to  thefe  experiments,  namely,  that  it  is  uncer- 
tain whether  in  thefe  fmall  diftances  the  force  of  gravity  follows  exadtly  the  fame  law  as  in 
greater  diftances.  There  is  no  reafon  however  to  think  that  any  irregularity  of  this  kind 
takes  place  until  the  bodies  come  within  the  aftion  of  what  is  called  the  attra£lion  of  co- 
hefion,  and  which  fecms  to  extend  only  to  very  minute  diftances.  With  a  view  to  fee 
whether  the  rcfuit  could  be  affedled  by  this  attradlion,  I  made  the  9th,  10th,  nth,  and  15th 
experiments,  in  which  the  balls  were  made  to  reft  as  clofe  to  the  fides  of  the  cafe  as  they 
could  j  but  there  is  no  difference  to  be  depended  on  between  the  refults  under  that  circum- 
ftance  and  when  the  balls  are  placed  in  any  other  part  of  the  cafe. 

"  According  to  the  experiments  made  by  Dr.  Mafkelyne  on  the  attraftion  of  the  hill 
Schehallien,  the  denfity  of  the  earth  is  4'-  times  that  of  water;  which  differs  rather  more 
from  the  preceding  determination  than  I  fhould  have  expected.  But  I  forbear  entering  into 
any  confideration  of  which  determination  is  moft  to  be  depended  on,  till  I  have  examined 
more  carefully  how  much  the  preceding  determination  is  affected  by  irregularities  whof« 
j^uantity  I  cannot  meafure." 


VJ.  An 


■  On  the  Chemical  Properties  attributed  to  Light.  453 

vr. 

An    Inquiry   concerning    the   Chemical  Properties  that  have  been  attributed  to  Light.      Bf 
Benjamin,  Count  of  Rumford,  F.  R.  S.  AL  R.  L  J. 


H, 


(Concluded  from  prfgc  405.) 


.  AVING  been  fo  fuccefsful  in  my  attempts  to  reduce  the  oxide  of  gold,  by  means  of 
charcoal,  in  the  moijl  ivay^  1  lod  no  time  In  making  fimilar  experiments  with  the  oxide  of 
filver. 

Experiment  No.  11.  A  folution  of  fine  filver,  In  ftrong  nitrous  acid,  was  evaporated  by 
drynefs,  and  the  refiduum  re-difTolved  in  diftilled  water. 

A  portion  of  this  foiution  (which  was  perfeftly  colourlefs),  diluted  with  twice  as  much 
diftilled  water,  was  poured  into  a  phial  containing  a  number  of  fmall  pieces  of  charcoal  j 
and  the  phial,  being  well  clofed  with  a  new  cork  ftopple,  was  expofed  to  the  a£lIon  of  the 
fun's  rays. 

In  lefs  than  an  hour  fmall  fpecks  of  revived  filver  began  to  make  their  appearance  on  the 
furface  of  the  charcoal ;  and,  at  the  end  of  two  hours,  thefe  fpecks  became  very  nume- 
rous, a^.d  had  increafed  fo  much'in  fize,  that  they  were  diflindly  vifible  to  the  naked  eye 
at  the  diftance  of  more  than  three  feet.  They  were  very  white,  and  poflelTed  the  metallic 
fplendour  of  filver  in  fo  high  a  degree,  that  when  enlightened  by  the  fun's  beams  their  luflre 
was  nearly  equal  to  that  of  very  fmall  diamonds. 

The  phial,  which  was  in  the  form  of  a  pear,  and  about  i^  inch  in  diameter  at  its  bulb, 
was  very  thin,  and  made  of  very  fine  colourlefs  glafs  \  the  aqueous  folution  was  alfo  per- 
feftly  tranfparent  and  colourlefs  ;  and,  when  the  contents  of  the  phial  were  illuminated  by 
the  diredt  rays  of  a  bright  fun,  the  contrail  of  the  white  colour  of  thefe  little  metallic  fpan- 
gles  with  the  black  charcoal  to  which  they  were  fi.xed,  and  their  extreme  brilliancy,,  aiForded 
a  very  beautiful  and  interefting  fight. 

As  the  air  had  been  previously  expelled  from  the  charcoal  by  boiling  it  in  diftilled  water, 
it  was  fpecifically  heavier  than  the  aqueous  folution  of  the  metallic  oxide,  and  confequently 
remained  at  the  bottom  of  the  bottle. 

Experiment  No.  12.  A  phial  as  nearly  as  pofirble  like  that  ufcd  in  the  laft  experiment, 
and  containing  the  fame  quantity  of  diluted  aqueous  folution  of  nitrate  of  filver,  and  alfo 
of  charcoal,  was  inclofed  in  a  cylindrical  tin  box,  and  expofed  one  hour  to  the  heat  of 
boiling  water  in  an  apparatus  ufed  for  boiling  potatoes  in  Ream  for  the  table. 

The  refult  of  this  experiment  was  uncommonly  ftrlking  :  the  furface  of  the  charcoal  was 
covered  with  a  mod  beautiful  metallic  vegetation  ;  fmall  filaments  of  revived  filver,  refem 
bling  fine  flatted  filver  wire,  pufliing  out  from  its  furface  in  all  dire£lions  ! 

Some  of  thefe  metallic  filaments  were  above  one-tenth  of  an  inch  in  length.  On  agitat- 
ing the  contents  of  the  phial,  they  were  eafily  detached  from  the  furface  of  the  charcoal,  to 
which  they  feemed  to  adhere  but  very  flightly. 

Thefe  experiments  were  repeated  feveral  times,  and  always  with  precifely  the  fame  re- 
fults. 

When  the  oxide  of  gold  was  reduced  In  this  way,  the  revived  metal  appeared  under  the 

form  of  fmall  fcales,  adhering  firmly  to  the  furface  of  the  charcoal.  May  not  the  difference 

Vol.  II. — Jan.  1799.  3  N  .of 


454  0"  '^^  Chemical  Properties  attribuUd  to  Liglt. 

of  the  ioTivs  under  which  gold  and  filver  are  revived  from  their  oxides,  in  this  procefs,  be 
owing  to  the  difference  of  the  fpecific  gravities  of  thofe  metals  ? 

The  following  experiments,  which  were  firft  fuggefled  by  an  accident,  were  made  with 
a  view  to  inveftigate  ftill  farther  the  caufes  of  thofe  efFeds  which  have  been  attributed  to 
the  fuppofed  chemical  properties  of  light. 

Having  accidentally  put  away  two  fmall  phials,  each  containing  a  quantity  of  aqueous 
folution  of  the  oxide  of  gold  and  fulphuric  ether,  in  each  of  which  the  ether  had  extradled 
the  gold  completely  from  the  folution,  as  was  evident  by  the  yellow  colour  of  the  folution 
having  been  transferred  to  the  ether,  and  the  folution  being  left  colourlefs  ;  in  one  of  the 
phials,  which  happened  to  ftand  in  a  window  in  which  there  was  occafionally  a  flrong 
light  (though  the  direft  rays  of  the  fun  never  fell  on  it),  I  found,  in  about  three  weeks,  that 
the  oxide  was  almoft  entirely  reduced  ;  the  revived  gold  appearing  in  all  its  metallic  fpien- 
dour  in  the  form  of  a  thin  pellicle,  fwimming  on  the  furface  of  the  aqueous  liquor  in  the 
phial,  and  the  colour  of  the  ether  which  repofed  on  it  having  become  quite  faint;  while  no 
vifiblc  change  had  been  produced  in  the  contents  of  the  other  phial,  which  had  flood  in  a 
dark  corner  of  the  room. 

As  thefe  appearances  induced  me  to  fufpcdl:,  or  rather  (trengthencd  the  fnfpicions  I  had 
before  conceived,  that  the  reparation  of  gold  from  ether,  under  its  metallic  form,  when  a. 
folution  of  its  oxide  is  mixed  with  that  fluid,  is  always  effeded  by  a  redudion  of  the  oxide 
by  means  of  light,  I  made  the  following  experiment,  with  a  view  to  the  farther  inveftiga-- 
tion  of  that  matter. 

Experiment  No.  1 3.  Into  a  fmall  pear-like  phial  of  very  fine  tranfparent  glafs  I  put  equal 
quantities  of  an  aqueous  folution  of  the  muriatic  oxide  of  gold  and  fulphuric  ether;  and 
the  phial,  which  was  about  h;.lf  filled,  being  clofcd  with  a  good  cork  well  fecured  in  its  place, 
was  expofed  to  the  adion  of  the  direft  rays  of  a  bright  fun. 

A  pellicle  of  revived  gold,  in  all  its  metallic  fplendour,  began  almoft  immediately  to  be 
formed  on  the  furface  of  the  aqueous  liquid,  and  foon  covered  it  entirely  ;  and  at  the  end' 
of  two  hours  the  whole  of  the  oxide  was  completely  reduced,  as  was  evident  from  the  ap- 
pearance of  the  ether,  which  became  perfeff/y  colourlefs. 

On  (baking  the  phial,  the  metallic  pellicle,  which  covered  the  furface  of  the  aqueous  Ii^ 
quid,  was  broken  into  fmall  pieces,  which  had  exafUy  the  appearance  of  leaf-gold,  pofTelT- 
ing  the  true  colour  and  all  the  metallic  brilliancy  of  that  metal. 

On  fufFering  the  phial  to  ftand  quiet,  the  aqueous  liquor  and  the  ether  feparated,  and 
moft  of  the  broken  pieces  of  the  thin  Iheet  of  gold  defcended  to  the  bottom  of  the  phial : 
the  remainder  of  them  floated  on  the  furface  of  the  aqueous  liquid  ;  and  the  ether,  as  well 
as  the  aqueous  liquid,  appeared  to  be  perfe£tly  tranfparent  znA  colourlefs. 

By  the  length  of  time  which  was  required  for  the  ether  and  the  aqueous  liquid  to  fepa- 
rate,  I  thought  I  could  perceive  that  the  ether  had  loft  fomething  of  its  fluidity ;  but  aa 
this  was  an  event  I  expected,  it  is  the  more  likely,  on  that  account,  that  1  was  deceived, 
when  I  imagined  I  faw  proofs  of  its  having  taken  place. 

On  removing  the  cork,  after  the  contents  of  the  bottle  had  been  fufFered  to  cool,  there 
was  no  appearance  of  any  confiderable  quantity  of  air,  or  other  permanently  elaftic  fluid, 
having  been  either  generated  or  abforbed  during  the  experiment. 

Finding  that  the  oxide  of  gold  might  be  fo  completely  and  fo  expeditloufly  reduced  by 

means 


Oti^  the  Chemical  Propertlei  attributed  to  Light.  45^ 

means  of  ether,  I  conceived  it  might  be  pofllble  to  perform  that  chemical  procefs,  in  the 
tmift  ivay,  by  means  of  eflential  oils ;  and  this  conje£lure  proved  to  be  well  founded. 

Experiment  No.  14-  Upon  a  quantity  of  a  diluted  aqueous  folution  of  nitro-murlatc 
of  gold,  in  a  fmall  pear-like  phial,  about  li-  inch  in  diameter  at  its  bulb,  was  poured  a 
fmal!  quantity  of  etherial  oil  of  turpentine,  juft  as  much  as  was  fuiBcient  to  cover  the 
aqueous  folution  to  the  height  of  \  of  an  inch  ;  and  the  phiuj,  being  well  clofed  with  a 
good  cork,  well  fecured,  was  expofed  one  hour  to  the  heat  of  boiling  water  in  a  fteam- 
veflel. 

The  gold  was  revived,  appearing  in  the  form  of  a  fplendld  pellicle,  of  a  bright  gold  co- 
lour, which  floated  on  the  furface  of  the  aqueous  liquid.  The  oil  of  turpentine,  which, 
at  the  beginning  of  the  experiment,  was  as  pale  and  colourlefs  as  pure  water,  had  taken  a 
bright  yellow  hue ;  and  the  aqueous  fluid,  on  which  it  repofed,  had  entirely  loll  its  yel- 
low colour. 

On  {baking  the  phial,  its  contents  were  intimately  mixed ;  but,  on  fufFering  it  to  ftand 
quiet,  the  oil  of  turpentine  foon  feparated  from  the  aqueous  liquid,  retaining  its  bright 
yellow  hue,  and  leaving  the  aqueous  liquid  colourlefs. 

On  (baking  the  phial,  before  it  had  been  expofed  to  the  heat,  and  mixing  its  contents,  and 
then  fuffering  it  to  ftand  quiet,  the  oil  of  turpentine,  on  taking  its  place  at  the  top  of  the 
aqueous  folution,  was  not  found  to  have  acquired  any  colour ;  nor  was  the  bright  gold 
colour  of  the  folution  found  to  be  at  all  impaired.  When  liilphuric  ether  was  ufed  ir.- 
ftead  of  the  oil  of  turpentine,  the  effe£l:  was  in  this  refpe£l  very  different. 

To  find  out  whether  the  oil  of  turpentine  ufed  in  this  experiment,  and  which  had  ac- 
quired a  deep  yellow  colour,  had  loft  that  property  by  which  it  efFeiled  the  redu(flion  of 
the  metallic  oxide,  I  now  poured  an  additional  quantity  of  the  aqueous  folution  of  the 
oxide  into  the  phial,  and,  Ihaking  the  phial,  expofed  it  with  its  contents  to  the  heat  of 
boiling  water. 

After  it  had  been  expofed  to  this  heat  about  two  hours  I  examined  it,  and  found,  that 
though  a  confiderable  quantity  of  gold  had  been  revived,  yet  the  aqueous  liquid  ftill  re- 
tained a  faint  yellow  colour. 

The  oil  of  turpentine  had  acquired  a  deeper  and  richer  gold  colour,  approaching  to 
orange. 

To  the  contents  of  the  phial  I  now  added  about  half  as  much  diftilled  water,  and, 
mixing  the  whole  by  fhaking,  I  expofed  the  phial  again,  during  two  hours,  to  the  heat  of 
boiling  water ;  when  the  remainder  of  the  oxide  was  reduced,  and  the  aqueous  liquid  left 
perfectly  colourlefs. 

On  repeating  this  experiment  with  oil  of  turpentine,  and  varying  it,  by  ufmg  a  folution 
of  the  oxide  oiftlver  (an  aqueous  folution  of  nitrate  of  filver,)  inftead  of  that  oi  gold,  the 
refult  was  nearly  the  fame :  the  metal  was  revived,  and  the  oil  of  turpentine  acquired  a 
faint  greenilh- yellow  colour. 

I  alfo  revived  the  oxides  of  gold  and  of  filver  with  oil  of  olives,  by  a  fimilar  procefs,  with 
the  heat  of  boiling  water.  The  oil  of  olives  ufed  in  thefe  experiments  loft  its  tranfpa- 
rency,  and  became  deeply  coloured :  that  ufed  in  the  redu£lion  of  the  oxide  of  filver 
taking  a  very  deep  dirty  brown  colour,  approaching  to  black ;  and  that  employed  in 
reducing  the  oiide  of  gold  being  changed  to  a  yellowifli-brown,  with  a  purple  hue. 

3  N  2  In 


45(J  On  the  Chemical  Properties  attributed  to  Light. 

In  the  experiment  with  the  oxide  of  fiiver,  the  infide  of  the  phial,  in  the  region  where 
the  oil  repofed  on  the  aqueous  folution,  was  beautifully  filvtred,  the  revived  metal  form- 
ing a  narrow  metallic  ring,  extending  quite  round  the  phial ;  and,  in  both  experiments, 
fmall  detached  pellicles  of  revived  metal  were  vifible  in  the  oil,  and  adhered  in  feveral 
places  to  the  infide  of  the  phial,  forming  bright  fpots,  in  which  the  colour  of  the  metal 
aiid  its  peculiar  fplendoar  were  perfedliy  confpicuous. 

Experiment  No.  15.  As  carbon  \s  one  of  the  Gonflituerit  principles  of  fpirit  of  wine,  aj 
well  as  of  eflcntial  oils  and  fulphuric  ether,  I  thought  it  poffible  that  I  might  fucceed  in 
the  rediiftion  of  the  oxide  of  gold,  by  mixing  alcohol  with  an  aqueous  folutioti  of  nitro- 
muriate  of  gold,  and  expofing  the  mixture  in  a  phial  well  clofed  to  the  heat  of  boihng 
water ;  but  the  experiment  did  not  fucceed. 

By  pouring  upon  this  mixture  a  fmall  quantity  of  oil  of  olives,  and  expofmg  it  again  to 
the  heat  of  boiling  water,  the  gold  was  revived. 

Is  it  not  probable  that  the  reafon  why  the  oxide  was  not  reduced  by  alcohol,  is  the  mo- 
bility of  thofe  elements,  which  ought  to  acl  on  each  other,  in  order  that  the  cfFed  in 
queftion  may  be  produced  ?  I  have  no  doubt  but  the  oxide  would  be  reduced,  could 
the  alcohol  be  made  to  reft  on  the  furfacc  of  the  aqueous  folution  without  mixing 
with  it. 

I  wiflied  to  have  been  able  to  have  collcfled  and  examined  the  elaftic  fluids,  which 
probably  were  formed  in  pioft  of  the  preceding  experiments ;  but  my  time  was  fo 
much  taken  up  with  other  matters  that  1  had  not  leifure  to  purfue  thefe  inveftigatlons 
farther. 

In  order  to  fee  what  effe£ls  would  be  produced  by  the  heat  generated  at  the  furface  of 
an  opaque  body,  of  a  nature  different  from  thofe  hitherto  ufed  in  the  redu£lion  of  th« 
metallic  oxides,  and  one  that  is  little  difpofed  to  form  a  chemical  union  with  oxygen, 
[magnefta  alba)  wten,  being  immerfed  in  an  aqueous  folution  of  the  oxide  of  gold, 
the  rays  of  the  fun  were  made  to  impinge  on  it,  1  contrived  the  following  experi- 
ment. 

Experiment  No.  \6.  I  took  four  fmall  thin  phials,  A,  B,  C,  and  D,  of  very  fine  glafs, 
arid  putting  into  each  of  them  about  five  grains  of  dry  magnefui  alba,  I  filled  the  phial  Aj 
nearly  full,  with  a  faturated  aqueous  folution  of  the  oxide  of  gold. 

I  filled  the  phial  B,  in  like  manner,  with  fome  of  the  fame  folution,  diluted  with  an 
equal  quantity  of  dillilled  water;  and  the  phials  C  and  D  were  fiiled  with  the  folution 
ftill  farther  diluted. 

Thefe  phials,  open  or  without  (loppers,  were  expofed  one  whole  day  to  the  action  of  the 
direct  rays  of  a  bright  fun,  their  contents  being  often  well  mixed  together  during  that 
lime  by  fliakirjg. 

The  contents  of  all  thefe  phials  changed  colour  more  or  lefs,  but  they  acquired  very  difir 
ferent  hues.  The  contents  of  the  phial  A  became  of  a  very  deep  rich  gold  colour,  ap- 
proaching to  orange,  the  earthy  fediment  being  throughout  of  the  fame  tint. 

The  contents  of  the  phial  B,  which  were  at  firft  of  a  light  ftraw  colour,  firft  changec^ 
to  a  light  green,  and  then  to  a  greenifh  blue.  The  phial  having  been  fuftered  to  (land 
quiet  feveral  days,  in  an' uninhabited  room  in  a  retired  part  of  the  houfe,  the  folution  bc^ 
came  nearly  colourlefs,  and  the  fediment  was  found  to  be  of  a  dirty  olive  colour. 

The 


jdccoutit  of  the  Perjian  Cotton-Tree.  4.57) 

The  colour  of  the  contents  of  the  phials  C  and  D  was  changed  nearly  in  the  fame  man- 
ner ;  and  having  been  fuffered  to  {land  quiet  two  or  three  days  to  fettle,  the  folution  was- 
found  to  be  quite  colourlefs,  and  the  fediment  to  be  deeply  coloured.  There  was,  how« 
ever,  a  very  remarkable  difference  in  the  hues  of  the  two  phials  ;  that  of  the  phial  C  being: 
of  a  light  greenifli-blue  ;  while  that  in  the  phial  D  was  indigo,  and  of  fo  deep  a  tint  that 
It  might  eafily  have  been  taken  for  black. 

Thefe  appearances  were  certainly  very  ftriking,  and  well  calculated  to  excite  my  cu- 
r'lofity ;  but  I  arn  fo  much  engaged  in  public  bufinefs  that  it  is  not  at  prefent  in  my 
power  to  purfue  thefe  inquiries  farther.  I  wifli  that  what  I  have  done  may  induce  others, 
who  have  more  time  to  fpare,  to  devote  fonie  portion  of  their  leifure  to  thefe  interefting 
invelligations. 


VJI. 

Some  Jccount  of  the  Perfiaii  Cotton-Tree.  By  MaTTHEIV  Guthrie,  M.D.  F.R.S.  ^c.  bfc* 

V-<'OTTON  is  a  plant  of  both  the  old  and  the  new  world  ;  at  leafl:  it  is  found  wild  in 
both  :  but  I  have  my  doubts  whether  it  was  a  native  of  America  before  the  Europeans  car- 
ried it  over,  and  fliall  affign  reafons  for  my -incredulity  when  1  come  to  treat  of  the  Perftait 
niton,  which  is  the  very  fpecies  that  is  faid  to  be  American. 

Five  fpecies  of  the  cotton-tree  are  enumerated  by  Linnxus  ;  and  there  is  reafon  to  fuf- 
pe£l:  the  exiftence  of  a  fixth,  if  what  we  are  told  of  the  extreme  finenefs  and  filky  nature- 
of  a  particular  kind  reared  in  fome  of  the  Antilles  be  literally  true.  This  curious  variety  is 
Called  Siam  cotton,  becaufe  the  reed  was  originally  obtained  from  Siam. 

The  firft  fpecies  of  cotton  is  the  gojfypium  arloreum,  or  Indian  cotton-tree,  which  has  been 
cultivated  and  manufaftured  in  the  Eafl  Indies  from  the  rcmoteR  period  of  the  authentic 
hiftory  of  that  country,  or  between  three  and  four  thoufand  years.  It  delights  in  a  fandy 
foil. 

The  fecond  fpecies  is  the  gojfypuim  religtofum,  which  is  likewife  a  native  of  India,  and  a 
tree,  or  at  leaft  a  high  (hrub ;  l>ut  why  Linnjeus  dignified  it  with  fo  fingular  a  fpecific 
name  1  fliall  leave  the  learned  Afiatic  Society  in  Bengal  to  determine,  as  they  muft  know 
if  it  be  ufed  for  any  religious  purpofes  by  the.Bramins.  This  fpecies  of  cotton  is  faid  to- 
be  that  which  is  cultivated  by  the  French  in  Martinico. 

The  third  is  the  G.  harbndetife,  a  fpecies  of  biennial  cotton  flirub  cultivated  in  our  Bri- 
tifli  ifland  of  Barbadoe6,  from  which  it  obtains  its  fpecific  name.  I  believe  it  is  likewife 
the  fame  fpecies  which  is  cultivated  in  Jamaica. 

The  fourth  is  the  G.  hirfuttim,  an  A  merican./i^r^;7«;W  cotton  fhrub  in  the  warmer  pro- 
vinces, h\it  annual  \n  the  colder,  as  is  fometinies  the  cafe  with  plants  in  climates  where 
their  roots  lofe  their  vegetating  power  by  winter  froft. 

The  fifth  and  laft  fpecies  is  the  G.  herbaceum,  or  G.  annuutn,  an  annual  cotton  plant, 
vljich  rifes  to  th?  height  of  three  or  four  feet,  and  is  fown  and  reaped,  like  corn,  twice  a. 

f  Manchefter  Memoirs,  Vol.  V.  Part  I. 

5.  y«aEr 


458  Account  of  tie  Perpan  Cotton-Tree^ 

year  in  hot  countries,  and  once  a  year  in  colder  climates.     It  bears  a  large  yellow  flower 
■with  a  purple  centre,  and  fruit  about  the  fize  of  a  walnut  containing  the  cotton. 

This  is  the  famous  Perfian  cotton  properly  ihe  fubjedt  of  the  paper,  although  a  flight 
mention  of  other  fpecies  was  neceflary  to  give  a  more  complete  view  of  the  fubjedt.  Lin- 
naeus calls  it  a  native  of  America  ;  and  there  is  no  doubt  but  that  it  is  become  fo,  although 
there  is  much  more  reafon  to  fuppofe  America  naturalized  a  Perfian  plant  than  that  Perfia 
got  it  from  the  new  world ;  efpeci«lly  if  we  are  to  credit  a  paper  lately  prefented  by  a  Bri- 
tifli  merchant  to  the  Economical  Society  at  Peterfburgh,  in  which  it  is  pofitively  afferted 
that  feveral  of  the  European  nations  furnilhed  their  American  colonies  with  Perfian  cotton 
feed  procured  at  Smyrna.  Now  this  fa£l  (if  fufBciently  authentic,  which  I  do  not  doubt 
from  my  knowledge  of  the  veracity  of  the  author)  will  eafily  account  for  the  G.  herbaceum 
being  found  wild  in  America  •,  when  we  recoilefl:  the  wonderful  provifion  of  nature  for  the 
wide  difperfion  of  feeds,  and  Linnxus's  affertion  that  the  Erigeron  canadenfe  was  difpcrfed 
from  the  botanic  garden  of  Paris  by  the  winds  over  a  great  part  of  Europe,  and  feveral 
other  plants*  from  the  botanic  garden  of  Upfal  over  a  whole  province. 

My  reafons  for  fuggelling  thefe  doubts  relative  to  the  native  country  of  this  fpecies  of 
cotton  are,  that  all  vegetables  of  this  genus  are  fuppofed  to  have  been  indigenous  in  Perfia 
exclufively,  and  that  even  the  Eaft  Indies  derived  the  cotton  plants  from  thence  ;  a  conjec- 
ture which  feems  to  have  acquired  fome  degree  of  credit  from  the  late  difcovery  of  Sir 
William  Jones,  viz.  that  the  Hindoos,  or  inhabitants  of  India,  were  originally  a  colony  of 
the  ancient  Iran  or  Perfia,  which  feems  to  have  been  the  cradle  of  the  human  fpecies,  fince 
its  ancient  language  appears  to  have  been  the  mother  of  all  thofe  now  exifting  (with  the 
exception  of  the  Arabic  and  Tartarian),  of  which  neverthelefs  it  contained  many  words. 

Now  it  is  very  poffible  that  the  firft  colony  carried  the  cotton  plant  with  them  to  India, 
and  that  it  was  afterwards  difpcrfed  from  Hindoflan  to  the  adjacent  countries  and  iflands. 
The  cotton  plant  is  widely  difperfed  likewife  throughout  Europe  and  fome  parts  of  Africa, 
particularly  the  annual  or  herbaceous  fpecies  (the  very  plant  treated  of  here)  reared  in  the 
north  of  Perfia,  and  which  is  alfo  cultivated  in  Malta  f,  Sicily,  Chio,  Lemnos,  and  other 
iflands  of  the  Archipelago,  although  poflibly  the  cotton  of  thefe  iflands  may  be  varieties  of 
the  fpecies  from  diflference  of  foil,  climate,  &c. 

The  beft  of  the  European  cotton  is  brought  from  Cyprus  ;  but  Smyrna,  Aleppo,  Da- 
mafcus,  Jerufalem,  &c.  furnifli  likewife  a  quantity  of  cotton  at  lead  equal  to  the  Eu- 
ropean. 

Cultivation  of  Cotton  in  Perfia, 

THE  annual  cotton,  or  this  laft  fpecies,  of  which  we  have  treated  more  amply,  is  much 
cultivated  in  the  northern  or  colder  provinces  of  Perfia  bordering  on  the  Cafpian  Sea  (as 
..the  perennial  is  in  the  fouthern)  ;  and  it  is  from  thence  that  the  feeds  now  fent  to  Portugal 
have  been  obtained  through  the  Bucharian  Tartar  merchants,  and  are  the  produdlion  of 
the  GoJJypium  herbaceum  of  Linnaeus,  the  Gojfypium  annuum  of  Pallas.  It  is  fown  in  Perfia 
from  the  end  of  March  to  the  end  of  April,  and  reaped  in  September.  This  fpecies  re 
quires  a  rich  foil  mixed  with  fand  ;  and  therefore  where  the  land  is  not  rich  enough  they 

•  The  Antirrhinum  minus,  the  Datura  ftrantonium,  the  Gnaphalium  amcricanum,  &c. 
f  There  is  a  kind  of  cotton  cultivated  in  Malta,  of  a  nankeen  colour*  which  exceeds  in  finenefs  all  other 
cotton,  and  is  much  fuperior  even  to  that  from  the  Antillet. 

manure 


Pftfian  Cctton'Trei.-~-Meofure  and  Expenee  of fnji  Movers.  459: 

manure  it  with  cow  or  (heep  dung ;  although  we  are  told  that  when  the  plants  are  once  raifed 
above  the  ground  any  fpecies  of  foil  will  anfwer.  The  ground  is  worked  in  the  fpring,  arid 
the  feeds  are  planted  at  the  diftance  of  eight  or  ten  inches  from  one  another,  whillt  care  is 
taken  to  weed  it,  to  give  air  to  the  young  plants.  Dry  fummers  give  the  bed  crop,  as  rain 
is  more  particularly  hurtful  when  it  falls  in  great  quantities  during  the  flowering  and 
ripening  of  the  cotton.  It  is  gathered,  as  fiid  above,  in  September,  care  being  always  taken 
to  colle£l  a  fulllcient  quantity  of  feed  for  the  next  year.  LalHy,  watering  the  young  planii- 
with  a  mixture  of  vvood-aflies  and  water  in  certain  fituations  is  fometimes  nccelTary  to 
guard  them  from  deftruflive  worms. 

The  RufiTi-ins  have  cultivated  the  fame  fpecies  of  Perfian  cotton  in  the  government  of 
Caucafus,  and  rear  enough  of  it  to  ferve  their  own  national  manufa£lures,  which  are  not 
as  yet  either  numerous  or  confiderable  j  but  on  the  Terek,  at  the  foot  of  the  Caucafus,. 
where  it  is  reared,,  they  do  not  fow  till  the  middle  of  May,  left  a  late  fpring  froft,  which  is 
fometimes  felt  in  thofe  parts,  fliould  deftroy  the  hopes  of  the  planter.  With  that  one  ex- 
ception, the  RuflTians  ftriftly  obferve  the  Perfian  mode  of  cultivation. 

There  is  a  fpecies  of  filky  cotton  much  cultivated  at  prefent  in  Germany,  which  poffibly 
may  merit  the  attention  of  Portugal  for  their  plantations  in  America.  It  is  the  AJclepias 
fyriaca  of  Linnaeus,  and  affords  fo  fine  a  fpecies  of  cotton  (if  I  may  fo  name  it)  that  fabrics 
have  been  erected  in  Saxony,  where  ftuffs  are  made  of  it  which  rival  in  luftre,  &c.  the 
true  animal,  fdk.  But  this  new  vegetable  filk  has  circumilances  attending  it  that  feem  to 
recommend  its  cultivation  in  fome  of  the  American  colonies  and  iflands :  Firft,  becaufe 
Jit  is  originally  the  native  of  a  hot  climate,  as  Linnseus's  fpecific  name  indicates ;  and  of 
courfe  it  is  likely  to  be  in  its  greateft  beauty  and  excellence  in  climates  which  approach 
neareft  to  that  of  its  native  country.  Secondly,  becaufe  its  (talks  afford  a  coarfe  fort  of 
cloth  well  calculated  to  clothe  negroes,  whilft  from  the  pith  of  them  paper  is  made. 

VIII. 

FaBs  and  Observations  concerning  the  Meafure  and  Expenee  of  JlrJ}  Movers,  namely.  Wind,, 
Watery  Steam,  and  Animal  Strength,  and  on  other  OhjeEls  of  general  Utility.     {JV.  N.), 

X  HE  confideration  of  the  value  and  Importance  of  natural  firft  movers  is  of  confe- 
quencc  not  only  to  pra£lical  engineers,  but  to  every  individual  in  cultivated  fociety.. 
There  are  numberlefs  fituations,  even-  in  the  fpirited  manufa£l:uring  kingdom  we  inhabit, 
where  large  revenues  are  expended  to  perform  mechanical  and  hydraulic  operations  by  the 
force  of  human  labour,  or  by  horfes,  which  might  be  for  the  moft  part  faved  by  fubftituting 
a  fteam-engine  or  windmill,  or  making  ufe  of  a  ftream  of  water  now  running  to  wafte.  It 
is  well  known,  that,  fince  the  extenfion  of  the  cotton  and  other  works,  eftates  of  fmall  rent 
in  the  neighbourhood  of  Manchefter  and  elfewhere  have  been,  and  continue  to  be,  let  at- 
more  than  twenty  times  their  original  rent,  merely  from  the  fortunate  circumftance  of' 
their  poffe fling  a  fmall  ftream  of  water  falling  with  a  fufficient  declivity  to  give  motion  to  a 
mill.  If  the  proprietors  of  lands  and  manufadlurers  in  general  were  better  acquainted  with 
the  fimple  methods  of  eftjmating  the  forces  of  thofe  currents  of  water  which  run  neglefted; 

through ; 


4.6o  •Benefits  arifuig  from  the  Application' of  inanimate  Jirjl  Movers. 

tlirough  their  grounds  and  premifes,  a.nd  which  an  intelligent  obferver  need  not  walk  mai^ 
miles  in  any  country  to  point  out,  their  property  and  revenue  might  immediately  receive  a 
confiderable  accefllon;  and  the  community  would  be  ftili  more  effectually  benefited.  The 
inceffant  demands  for  the  employment  of  fuch  forces  in  grinding  corn,  colours,  drugs,  to- 
bacco ;  in  cutting  bark  and  other  tanners'  and  dyers'  materials  ;  in  fawing  wood ;  in  la- 
minating, drawing,  or  fafnioning  metallic  bodies  ;  in  fpinning,  v.'cavlng,  fulling,  &c.  the 
products  of  the  organized  kingdoms  by  arts  already  praclifed,  excliifivc  of  the  many  im- 
provements which  may  be  expe£led  in  their  application,  are  too  numerous  to  afford  the 
leaft  reafon  for  any  proprietor  to  fear  a  want  of  employment,  or  to  confider  the  ere£liou 
of  a  mill  in  a  proper  fituation  as  a  fpeculation  of  the  leaft  danger  or  probable  difadvantagc. 
Similar  obfervations  are  to  a  certain  extent  applicable  in  favour  of  the  nfe  of  horfes  inftead 
of  men,  and  (learn  inftead  of  horfes,  in  every  cafe  where  the  power  is  required  to  be  great 
or  long  continued,  and  the  fkill  either  little,  or  capable  of  being  fupplied  by  machinery. 

I  am  teiTipted  to  digrefs  for  a  moment  from  my  fubjedl  by  the  natural  recurrence  of  a 
political  refleftion,  fo  obvious  that  it  fcarcely  ever  fails  to  be  made  when  the  extenuon  of 
machinery  and  the  application  of  inanimate  powers  are  confidered.  It  is  ftated  by  certain 
humane  but  miftaken  objeftors,  that  the  fcheme  of  mechanical  and  chemical  improve- 
ment is  pointed  againft  the  human  fpecies,  and  tends  to  drive  them  out  of  the  fyftcm  of 
beneficial  employment.  Two  creatures  offer  themfelves  to  me  for  employment  and  fup- 
port — a  man  and  a  horfe.  I  mult  invariably  prefer  the  latter,  and  leave  the  former  to 
..ftarve.  Two  other  beings — a  horfe  and  a  fteam-engine,  are  candidates  for  my  favour.  My 
preference  to  the  latter  tends  to  exterminate  the  fpecies  of  the  former.  In  both  cafes 
it  is  ftated,  that  the  number  of  intelligent  creatures  capable  of  the  enjoyment  of  happinefs 
muft  be  diminiflied  for  want  of  fupport ;  and  that,  on  the  whole,  the  fum  of  the  propofcd 
improvements  is  not  only  a  lefs  proportion  of  good  to  fociety,  but  a  pofitive  acceffion  of 
much  mifery  to  the  unemployed  poor. 

On  this  wide  and  extended  argument,  which  can  in  facfl  be  maintained  againft  improve- 
ments in  no  other  way  than  by  infifting  that  tlie  favage  ftate,  with  all  its  wants,  its  igno- 
rance, its  ferocity,  and  its  privations,  is  preferable  to  the  focial  intercourfe  of  effort  and 
divifion  of  labour  we  are  habituated  to  prefer,  it  may  be  fufficient  to  obferve,  that  the  topic 
includes  matter  not  only  for  reafoning  and  indudlion,  but  alfo-for  experiment.  By  refe- 
rence to  the  matter  of  fafl:,  though  it  muft  be  allowed  that  new  improvements,  which 
change  the  habits  of  the  poor,  muft  at  firft  expofe  them  to  temporary  inconvenience  and 
diftrefs,  againft  which,  in  fairnefs,  it  is  the  duty  of  fociety  to  defend  them  ;  yet  the  inva- 
riable refult  of  fuch  improvements  is  to  better  the  condition  of  mankind.  The  nations 
which  have  ftiewn  the  moft  ingenuity  and  induftry  in  this  way  are  not  only  the  richeft,  the 
moft  populous,  the  moft  intelligent,  and  the  beft  defended  ;  but  the  provinces  of  thofe 
rations  are  feen  to  flourifh  in  proportion  to  their  refpedlive  degrees  of  adivity  in  this  re- 
fpe£t.  And  from  thefe  exertions  it  is,  as  Smith*  emphatically  remarks,  that  "  the  accom- 
modation of  an  European  prince  does  not  always  fo  much  exceed  that  of  an  induftrious 
and  frugal  peafant,  as  the  accommodation  of  the  latter  exceeds  that  of  many  an  African 
kin£,  the  abfolute  mafter  of  the  lives  and  liberties  often  thoufand  naked  favages." 

•  Wealth  of  Nations,  i.  ch.  L 

Eut 


I>edii8lons  refpeBitig  the  Power  ofWtndmlllSf  ^c.  46« 

But  to  return  to  our  fubjecl.  In  this  praftical  and  popular  communication  I  fliall  avoid 
entering  into  any  difcuffion  of  the  theory  of  windmills,  which  has  employed  the  attention 
of  fo  many  eminent  men  for  a  century  paft.  The  advantages  of  thefe  engines  for  fuch 
work  as  will  admit  of  being  performed  and  fufpended  by  intervals  are  fuflicientiy  known, 
but  perhaps  not  fulEciently  attended  to.  There  can  be  no  doubt  but  that  the  Dutch,  who 
ufe  windmills  for  fawing,  pumping,  arid  various  other  works,  as  well  as  grinding,  muft 
have  found  them  very  profitable,  fince  their  country  Is  overfpread  with  them.  It  may  be 
proper  however  to  take  notice,  that  many  writers  have  copied  one  from  another  the  deter- 
mination of  Maclaurin,  that  the  bed  angle  for  windmill-fails  to  make  with  the  line  of  di- 
re£lion  of  the  wind  is  54°  44',  which  is  only  true,  as  that  excellent  mathematician  obfervcs, 
at  the  very  commencement  of  the  motion,  and  requires  to  be  enlarged  as  the  velocity  of 
the  fails  increafes  :  for  the  law  of  which,  and  other  eflential  obje£ls,  his  account  of  Sir 
Ifaac  Newton's  Philofophical  Difcoveries,  and  his  Treatife  on  Fluxions,  may  be  confulted» 
Smeaton,  who  had  much  experience  in  the  bufinefs  of  a  civil  engineer,  and  whofe  data 
may  always  be  depended  on,  though  his  theories  are  not  conftantly  accurate,  made  a  fet 
of  experiments  on  the  conftru6lion  and  efFefts  of  windmill-fails,  which  are  defcribed  in 
the  Philofophical  Tranfaclions  for  the  year  1759*.  This  engineer  ftates,  that  the  mean 
rate  of  work  for  mills  with  Dutch  fails  is  when  they  make  about  thirteen  turns  in  a  minute, 
which  is  when  the  velocity  of  the  wind  is  8y  miles  in  an  hour,  or  ii\  feet  in  a  fecond : 
and  this  wind  in  common  phrafe  would  be  called  a  frefh  gale.  Taking  the  maximum  of 
Defaguliers,  hereafter  to  be  mentioned,  as  his  ftandard  for  computation,  he  deduces  the 
fize  of  a  windmill-fail  of  the  figure  juft  mentioned,  and  alfo  according  to  a  figure  con- 
ftru£led  from  his  own  experiments,  which  Ihall  be  equal  in  mean  power  to  one  man  ;  and 
tlience  he  arrives  at  the  inference,  that  one  of  his  own  fails,  thirty  feet  in  length,  will, 
when  working  at  a  mean  rate,  be  equal  to  the  power  of  18,3  men.  Ke  had  an  oppor- 
tunity of  verifying  this  in  the  large  way  in  a  mill  ufed  for  cru  filing  rape-feed.  The  mean 
power  of  a  windmill  is  therefore  very  confiderable  j  but  what  may  be  the  annual  or  ave- 
rage quantity  of  work  fuch  an  apparatus  is  capable  of  performing  under  all  the  viciflitudes 
of  the  wind,  I  poffefs  no  means  of  afcertaining. 

In  the  fame  treatife  Smeaton  makes  feveral  very  jufl:  remarks  on  thofe  windmills  which 
are  a£led  upon  by  the  dire£t  impulfe  of  the  wind  againfl:  fails  fixed  to  a  vertical  fliaft.  His 
objections  have,  I  believe,  in  every  infi:ancc  been  juftified  by  the  inferior  eflicacy  of  thefe 
mills  when  compared  with  the  charges  of  ere£ling  them.  He  alfo  maintains  that  water- 
mills  with  oblique  fails,  upon  the  principle  of  the  common  windmill,  cannot  prove  benefi- 
cial to  the  undertaker.  It  is  indeed  probable  that  mod  of  the  circumftances  of  running- 
water  are  likely  to  render  the  common  over  and  underfliot-wheels  cheaper  and  more  ef- 
feftual,  and  that  the  oblique  float-board  will  in  no  inftance  come  near  the  efi^ecl  of  a  clofe 
overfliot  wheel.  But  it  is  alfo  certain  that  fuch  wheels  are  ufed  in  China,  in  the  fouth  of 
France,  and  elfewhere,  with  much  more  tSodc  than  Smeaton-  appears  difpofed  to  think 
them  capable  of :  and  at  all  events,  the  fubjefl  of  thefe  wheels  deferves  to  be  confidered. 

'*  This  account  has  fince  been  repiibilihed,  together  with  o\\\t\i  valuable  papers  of  the  fame  author,  under 
the  title  of  kn  Experimental  Inquiry  concerning  the  Natural  Powers  of  Wind  and  Water  to  turn  Mills,  &c. 
By  John  Smeaton,  T.  R.  S.  8TO,--printed  for  Taylor,  London,  1794. 

-Vol..  n.— Jan, -1 799'.  3O  ^  The 


'4(J2  Meliod  of  Jrtefmmng  the  Power  of  a  Stfeam  cflVofer. 

The  enquiry  which  moft  immediately  interefts  land-holders,  and  others  who  have  the  ad- 
vantage of  a  current  of  watef,  is  to  afccrtain  w  hether  it  will  afford  fufficient  power  to  juftify 
the  ereclion  of  a  mill,  and  what  that  power  may  be.  If  the  ftream  be  ample  without  much 
fall,  it  muft  necefTarily  be  applied  to  move  an  undcrfliot  wheel  by  its  impulfe,  and  the  power 
will  be  determinable  from  the  velocity  of  the  water,  and  the  quantity  which  paffes  through 
the  feclion  of  its  bed.  One  of  the  eafieft  methods  of  afcertaining  thefe  data  is  that  given 
by  Dcfaguliers  *,  as  follows.  Obferve  a  place  where  the  banks  of  the  river  are  deep  and 
parallel,  fo  as  to  make  a  kind  of  trough  for  the  water  to  run  through,  and  by  taking  the 
depth  acrofs  make  a  true  feftion  of  the  river.  Stretch  a  firing  at  right  angles  over  it, 
and  at  a  fmall  diftance  another  parallel  to  the  firft.  Then  take  an  apple,  an  orange,  cr 
other  fmall  b-.ll,  juft  fo  much  lighter  than  water  as  to  fwim  in  it,  and  throw  it  into 
the  water  above  the  ftrings.  Obferve  when  it  comes  under  the  firfl.  firing  by  means  of  an 
half-fecon.l  pendulum,  a  ftop-watch,  or  any  other  proper  inftrument,  and  likewife  when 
it  arrives  at  the  fecond  firing.  By  this  means  the  velocity  of  the  upper  furface,  which  ia 
praflicc  may  generally  be  taken  for  that  of  the  whole,  will  be  obtained.  The  fe(flion  of 
the  river  at  the  fecond  firing  muft  be  afcertained  by  taking  the  depth  as  before.  If  this 
furface  or  feftion  be  the  fame  as  the  former,  it  may  be  taken  for  the  mean  feclion  ;  if  not, 
add  both  together,  and  take  half  the  fum  for  the  mean  fecTion.  The  area  of  the  mean 
fe£lion  in  fquare  feet  being  then  multiplied  by  the  diftance  between  the  ftrings  in  feet, 
will  give  the  contents  of  the  water  in  folid  feet,  which  pafTed  from  one  firing  to  the  other 
during  the  time  of  obfervation.  And  this,  by  the  rule  of  three,  may  be  adapted  to  any 
other  portion  of  time.  Suppofe,  for  example,  the  time  had  been  12",  and  the  hourly  ex- 
penditure of  water  were  required,  the  proportion  would  be  :  As  12"  are  to  3600',  fo  is  the 
number  of  cubic  feet  obferved  to  the  hourly  expenditure  in  cubic  feet.  If  the  mere  velo- 
city be  required  in  proportion  to  any  fixed  interval  of  time,  the  fame  proportion  will  give 
it,  provided,  inftead  of  the  folid  contents  in  the  third  term,  there  be  taken  the  difiance 
between  firing  and  firing. 

The  intelligent  obferver  may  in  general  abridge  this  operation,  by  taking  notice  of  the  ar- 
rival of  the  floating  body  oppofite  two  fiations  on  the  fiiore,  efpecially  when  it  is  not  conve- 
nient to  ftrctch  a  firing  acrofs.  The  arch  of  a  bridge  is  a  good  ftation  for  an  experiment  of 
this  kind,  becaufe  it  affords  a  very  regular  fedion  and  two  fixed  points  of  obfervation  :  and 
in  fomc  inftances  the  fea  pradice  of  heaving  the  log  may  have  its  advantages.  Where  a 
time-piece  is  not  at  hand  it  may  fee  equally  convenient,  provided  two  obfervers  attend,  to 
note  the  time  with  a  half  or  quarter-f  conds  pendulum.  The  half-feconds  pendulum  is 
made  by  fufpending  a  fmall  round  button,  or  other  fpherical  weight,  by  a  thread  looped 
over  a  pin  of  fuch  a  length  that  the  difiance  from  the  bend  of  the  loop  to  the  centre  of 
the  weight  fliall  be  9,8  inches.  1  he  quarter-feconds  pendulum  is  one  fourth  of  this 
length.  If,  by  obfervations  at  feverai  fiations  above  and  below  any  particular  point  of  the 
river,  the  velocity  is  not  found  to  vary,  the  fedlion  of  the  river  in  all  that  fpace  may  be 
concluded  to  be  uniform  ;  and  it  will  not  be  neceffary  to  determine  more  than  one  fedlion 
by  actual  meafurement- 

In  the  cafe  of  an  overflowing  pond,  or  fmall  fiream,  which  will  admit  of  a  dam  acrofs  it, 

*  Courfeof  Expeiimental  Philofophy,  ii.  419. 

the 


Method  of  deter  mtnlng  the  Expence  and  Power  of  a  Stream  of  Water.  463 

the  quantity  of  water  afforded  may  be  afcertained  by  fufFerlng  It  to  run  through  a  notch 
in  a  board,  or  a  vertical  hole  of  an  inch  fquare,  according  to  the  following  table,  which 
Defaguliers  fays  he  calculated  from  repeated  experiments*. 


A  TABLE  of  the  Expence  of  Water  through  an  Inch  fquare  Hole,  and  through  a  Cut  an  Inch 

wide  and  of  different  Depths. 


Inches  below  the 
furface. 


I 

a 

3 

4 

5 

6 

7 
8 

9 

10 

II 
12 
»3 

15 
16 

17 
18 

19 

20 
21 
22 

i3 

24 

25 


Expence  of  water  through  a 
hole  of  a  fquare  inch  at  dif- 
ferent depths,  according  to 
the  number  of  inchss  in  the 
firft  column. 


Expence  of  water  through  i 
notch  of  different  depths, 
according  to  the  number  of 
inches  in  the  firft  column 


Tuns  in  an  ] 

Hour. 

-        1,04 

- 

- 

- 

1,04 

-       1,4^ 

- 

- 

- 

2,50 

-       1.79 

- 

- 

- 

4.29 

2,08 

- 

- 

- 

6,37 

-      2,31 

- 

- 

- 

8,68 

-      2,53 

*• 

- 

11,21 

-      2,74 

- 

- 

- 

J3.9S 

-       2,92 

- 

■- 

- 

16,87 

-      3.'2 

- 

- 

- 

19,19 

-    3.28 

- 

- 

- 

22,4.7 

-      3.44 

- 

- 

V 

25,8  r 

-      3,58 

■« 

- 

- 

29,39 

-      3.74 

- 

- 

- 

33.13 

-      3.88 

- 

- 

- 

36,91 

-      3.95 

- 

- 

- 

40,86 

-      4.i<5 

- 

- 

- 

45.02 

-      4,28 

- 

- 

- 

49.30 

-      4.40 

- 

- 

- 

53.70 

-      4,52 

- 

- 

- 

S8,»2 

-      4.62 

- 

- 

- 

62,84 

-      4.76 

- 

- 

«• 

67,60 

-      4,87 

- 

- 

- 

72.47 

-      4.94 

- 

- 

- 

77.41 

•      5.06 

- 

- 

- 

82,47 

-      5.2. 01^ 

- 

- 

- 

87.67 

5  tuns 

and  50,4  gallons. 

A  cubic  foot  of  water  weighs  very  nearly  624-  pounds  averdupois,  and  an  hogfliead  of 
water  weighs  about  550  pounds. 


•  Courfe  of  Experimental  Pliilofophy,  ii,  iij, 
3  O  2 


la 


4(^4  InJivuBhns  for  meafnringthf  Force  of  a  Stream y  and  determining- 

In  the  confideration  of  power  or  forcf  to  be  derived  from  water  in  motion,  thi  water 
may  be  taken  as  a  determinate  mafs  falling  through  a  given  height  in  a  given  time.  In 
order  that  this  defcending  weight  may  caufe  another  weight  to  afcend,  or  may  overcome 
fome  refiftance  in  the  way  of  work  with  that  degree  of  fpeed  which  fliall  be  the  moft.  pro- 
fitable, it  is  neceflary  that  the  refiftance  or  work  to  be  done  fliould  be  neither  too  great  nor- 
too  little.  If  it  be  too  great,  the  flownefs  ef  operation  will  diminifii  the  quantity  of  work ; 
and  if  it  be  too  fmall,  the  fpeed  will  not  fufficiently  compenfate  for  this  fmallnefs.  When 
the  power  is  therefore  known,  it  remains  to  deduce  what  may  be  the  cffe£t.  But  in  the 
firft  place,  as  the  height  from  which  the  water  flowing  in  a  river  may  have  defcended,  in 
order  to  acquire  its  velocity,  is,  from  a  variety  of  circumftances,  difficult  to  be  afcertained, 
and  alfo  very  different  from  that  height  which  would  Immediately  and  without  impediment 
produce  the  fame  velocity,  it  becom.es  neceflary  to  compute  this  laft  height,  which  hydro- 
ftatical  writers  ufually  call  the  height  of  the  virtual  head.  Thefe  writers  teach,  that  the 
velocity  of  a  fluid  fpouting  through  an  orifice  in  a  thin  plate  is  the  fame  as  would  be  ac- 
quired by  a  body  falling  in  clear  fpace  from  the  height  of  the  furface  of  the  fluid  above  the 
©rifice.  Hsnce,  from  the  common  doftriue  of  falling  bodies,  if  the  unlforrri  velocity  of  a 
ftream  be  exprefled  in  feet  per  fecond,  the  virtual  height  of  the  fall  will  be  found  by  mul- 
tiplying the  given  velocity  into  itfelf,  and  dividing  the  produ£l  by  64,2882;  the  quotient 
will  be  the  required  height  eJf'prefled  in  feet  *. 

The  cfFeft  of  underftiot  and  overfhot-wheels  has  been  treated  by  various  authors,  who 
have  given  refults  extremely  different  from  each  other.  Smeaton,  in  the  Treatife  often^ 
quoted  in  the  courfe  of  this  communication,  obferves,  that  Belidor  in  his  Archite£lure  Hy- 
draulique,  1.  286,  endeavours  to  demonftrate  that  water  applied  uhderfliot  will  do  fix 
times  more  execution  than  the  fame  applied  overlhot ;  while  Defaguliers,  whom  he 
(Smeaton)  mifquotes  by  overlooking  the  difference  of  fail.  Is  faid  to  have  given  the  advan- 
tage as  ten  to  one  in  favour  of  the  overlhotf.  The  particular  experiments  of  Smeaton- 
himfelf,  as  well  as  his  experience,  point  out  the  following  refults. 

The  effefl;  in  underfliot-mills  in  the  large  way  is  at  beft  one  third'  of  the  power ;  that  is- 
to  fay,  the  wheel,  being  driven  with  two-fifths  of  the  velocity  of  the  ftream,  will  raife  a. 
quantity  of  water  equal  to  one-third  cf  the  column,  which  ftrikes  the  float-boards,  to  an 
height  equal  to  that  of  the  virtual  head  or  fall :  and  the  effedl  of  an  overfliot- wheel  will 
be,  at  a  medium,  twice  that  of  the  underfliot.  Mills  having  a  breaft-wheel,  or  other  kind 
of  wheel  on  which  the  water  ads,  partly  by  its  weight  and  partly  its  impulfe,  will  produce 
more  or  Icfs  effed,  accordingly  as  the  circumftances  approach  more  nearly  to  thofe  of  the 
over  or  underlhot-wheels. 

For  the  advantage  of  fuch  as  are  leaft  converfant  in  fubjeifls  of  this  nature,  for  whom 
chiefly  the  prefent  memoir  is  intended,  I  ftiall  illuftrate  the  fubjedt  by  an  example. 

Suppofe  a  ftream  to  pafs  through  an  eftate  without  any  evident  fall,  with'  a  velocity  of 
nine  feet  per  fecond,  and  affording  fuflScient  room  to  place  an  underftiot-wheel  with  a  pro- 

*  The  f  rcof  of  this  is  fimpU-.but  may  alfo  be  feen  in  Delagiiliers,  ii.  510.— Thofe  who  ufe  logarithms  may 
with  Icfb  trouble /ai/rafl  tie  conjiant  log.  i.icSi^\2  from  Itvlce  tit  log.  nf  tkt  veheily,  and  the  remainder  wili  be  the  Itg. 
if  the  virtual  height. 

f  The  proportion  of  work  of  the  two  aftual  mills,  compared  by  Defaguliers,  is  as  3,25  to  1  in  favour  of  the 
«\?iiliot. 


itJ  EffeSi  on  underjhot  and  over/hot  Wheels,     .  *(,&■ 

per  number  of  float-boards,  each  fix  feet  long  and  two  deep  :  It  is  required  to  determine,. 
ift,What  quantity  of  water  might  be  raifed  by  that  power,  during  the  day  often  hours, 
to  the  height  of  thirty  feet  ?  or,  2dly,  VVhat  number  of  bufiiels  of  wheat,  or  malt,  might 
be  ground  in  the  fame  time  ?  or,  3dly,  What  number  of  men  or  horfes  might  this  wheel 
fupply  the  place  of,  in  performing  any  other  kind  of  work  or  manufadure  ? 

In  the  firft  place,  to  find  the  virtual  f<tll,.  multiply  9  feet  by  itfelf,  which  gives  8r,  and 
divide  this  by  64,2882:  the  quotient  will  be  1,26  feet. — Again,  the  furface  of  the  float 
being  6  feet  by  2  feet,  is  12  fquare  feet;  which,  multiplied  by  the  velocity  9,  gives  108  = 
the  number  of  folid  feet  of  water  which  has  in  cSqCl  fallen  from  the  virtual  head  in  a  fe- 
cond.  But  this  power  will  partly  be  confumed  in  producing  eddies  and  lateral  motions, 
and  partly  remain  uncommunicat^d  in  the  tail  watCi  as  it  flows  off.  P'or  which  rea- 
fons,  as  has  already  been  remarked,  the  effe£t  will  only  be  one-third  of  the  power.  That 
IS'  to  fay,  one-third  pare  of  108,  or  36  cubical  feet  of  water  will  be  raifed  in  a  fecond 
to  the  height  of  1,26  feet.  The  queftion  however  is  directed  to  the  height  of  thirty  feet, 
and  the  quantities  of  water,  or  other  weights,  raifed  by  equal  powers,  are  inverfely  as 
their  heights :  that  is,  30  feet  :  1,26  feet  ::  36  cubical  feet  :  1,512  cubical  feet  raifed 
30  feet  in  a  fecond.  But  the  hour  confifts  of  3600  fecondi,  and  the  day  of  ten  hours, 
=  360CO,  which  multiplied  bj  1,512  produces  54432  cubic  feet,  or  6437  hogflieads, 
(reckoning  the  gallon  at  231  folid  inches)  which  are  raifed  30  feet  in  the  day  *. 

With  regard  to  the  operation  of  grinding,  it  is  allowed  that  about  34.20  cubic  feet  of 
■water  with  a  fall  of  10  feet  will,  by  an  overfliot  wheel,  grind  one  bufliel  of  wheat  into 
Iteur,  and  the  fame  force  will  cut  five  quarters  of  malt.  But  our  underfhot  wheel  will-, 
only  do  half  the  work.  From  the  foregoing  calculations  our  flream  is  equivalent  to  13,6 
folid  feet  per  fecond  with  a  fall  of  ten  feet,  or  8  1  6,5  folid  feet  per  miimte.  Therefore 
as  3420  cubic  feet  :  one  bufliel  of  wheat  :  :  816,5  cubic  feet  :  0,239  of  a  bufhel  which 
would  be  ground  per  minute  by  an  overfliot  wheel ;  or  0,1195  by  our  underfliot  wheel.. 
This  lafl;  number  multiplied  by  60  produces  71,7  bufliels  per  hour,  or  nearly  72  bulhels 
or  9  quarters  of  wheat  per  day  of  ten  hours.  And  by  the  proportion  of  malt  to  wheat 
juft  mentioned,  it  will  follow  that  360  quarters  of  the'  former  grain  might  be  cut  in  the- 
fame  time. 

Animal  ftrength  is  of  fo  flufluating  a   nature,  that  it  is  difficult  to  fubje£l:  it  to  any 
^ftimate.     Phyfical   caufes    muft  affeft  both  the  quantity  and  duration  of  the  efforts 

•  This  is  an  outfide  eftimate,  and  gives.no  allowance  for  friftions  and  errors  in  tHe  conftruftion  of  the  liy- 
draulic  work.     The  reaft'on  in  Smeaton's  Experiments  was  afforded  merely  by  a  weight  and  pulley,  which 
isgreailyin  favour  of  the  mill  in  deducing  the  effe£t.    I  find  in  the  "  Reports  of  the  late  Mr.  John  Smeaton 
F.  R.  S.''  printed'in  quarto,  London  1797,  the  power  of  the  water  called  "  Hubbert's  mill  ftream'.'  is  deduced- 
from  the  quantity  and  fall,  <  p.  24;.)  by  a  rule  which  he  does  not  mention,  but  is  evidently  this,  for  overfliot  ov. 
clofe  brcaft  wheels  :   Multiply  the  number  of  cubic  feet  of  -water  ciifc  barged  per  minute  by  the  fall  in  feet :  this 
number  may  be  called  the  power.     Dii/ide  the  ptnver  byiwo,  and  t!je  quotient  may  be  called  the  effe^.     AJfiimt  ^ 
any  height  ot  pleafure  in  feet  t  divide  the  effeii  b^  the  height,  and  the  quotient  -will  be  the  cubic,  feet  of'iuater 
•vjhich  a  good  hydraulic  apparatus  ivitl  raife  to  that  height  per  minute. 

The  underfhot  wheel  will  raife  half  that  quantity  :  or  in  general  lefs  than  one-fixth  of  the  power; 

I  have  retained  the  proportion  of  tht  Treatife  on  mills  in  the  text,  becaufc  the  ratio  of  the  efteft  to  the  power. 
Kin  be  eafily  altered  at  pleasure  in  computing, 

poffibJqi.  • 


4&6  Invefligathn  of  the  Poivers  of  Men  and  Horfes. 

poflible  to  be  made  either  by  man  or  bead,  and  the  former  is  more  particularly  influenced 
by  his  moral  habits.  From  thefe  laft  it  is  that  the  influence  of  reward,  the  expe£l:atlon 
of  favour  or  patronage,  and  various  other  fimilar  motives,  have  operated  in  the  temporary 
exhibition  of  hydraulic  machines,  to  produce  refults  contrary  to  every  found  deduclion 
from  permanent  work,  and  moft  pernlcioufly  delufive  to  the  parties  concerned  in  fup- 
■porfing  or  encouraging  fuch  engines.  Defaguliers*,  who  has  taken  much  pains  to  afcer- 
tain  the  maximum  of  power  in  this  refpcft,  has  determined  that  a  man  can  raife  of  water, 
or  any  other  weight,  about  550  lbs.  or  one  hogfliead  ten  feet  high  in  a  minute ;  and  he 
■ftates  that  a  horfe  will  raife  five  times  that  quantity ;  or,  which  is  the  fame  thing,  that 
quantity  through  five  limes  the  height.  His  dedutStion  rcfpefling  the  man,  though  he 
fays  it  will  hold  good  for  fix  hours,  appears  from  his  own  fa£ls  to  be  too  high,  and  cer- 
tainly fuch  as  could  not  be  maintained  one  day  after  another.  Smeaton  f  confiders  this 
work  as  the  effort  of  hade  or  diflrefs.  He  reports  J  that  fix  good  Englifh  labourers  will 
be  required  to  ra'fe  2  1 141  folid  feet  of  fca  water  to  the  height  of  four  feet  in  four  hours. 
This  quantity  is  of  the  fame  weight  as  21669  cubic  feet  of  frefli  water,  with  which,  and 
the  above  rate,  it  will  be  found  by  an  eafy  calculation  that  the  men  will  raife  a  very  little 
more  than  fix  cubic  feet  each  to  the  height  of  ten  feet  in  a  minute.  Bat  the  hogfliead  con- 
taining 8^  cubic  feet,  Smeaton's  allowance  of  work  proves  lefs  than  that  of  Defaguliers  in 
the  proportion  of  6  to  84^.  And  as  his  good  Englilh  labourers,  who  can  work  at  this  rate, 
are  by  him  ellimated  to  be  equal  to  a  double  fet  of  common  men  picked  up  at  random  ;  it 
feems  very  proper  to  Rate  that,  with  the  probabilities  of  voluntary  interruption,  and  other 
incidents,  a  man's  work  for  many  days  together  ought  not  to  be  eftimated  at  more  than 
half  a  hogfliead  raifed  ten  feet  high  in  a  minute.  In  the  fame  report  laft  quoted,  Smeaton 
ftates,  that  two  ordinary  horfes  will  do  the  work  in  three  hours  and  twenty  minutes,  which 
amounts  to  a  little  more  than  two  hogflieads  and  a  half  §  raifed  ten  feet  high  in  a  minute. 
One  horfe  will  therefore  do  the  work  of  five  men. 

To  apply  thefe  dedu£lions  to  our  example,  it  mufl:  be  recolle£led  that  the  quantity 
raifed  in  ten  hours  to  the  height  of  thirty  feet  was  inferred  to  be  6437  hogflieads,  which 
are  equivalent  to  32  hogflieads  raifed  ten  feet  high  per  minute.  Confequently  at  the  rate 
of  one  man  for  each  half  hogfliead,  the  ftream  would  perform  the  work  of  64  men,  or 
pearly  thirteen  horfes.  ' 

With  regard  to  ftreams  which  fall  by  a  confiderable  declivity,  the  water  may  be  con- 
veyed by  the  well  known  means  of  a  dam  or  trough  to  the  buckets  of  an  overfliot  wheel, 
placed  in  that  part  of  the  ftream  which  is  found  the  moft  convenient  in  point  of  expencc 
and  local  fituation.  Suppofe,  for  example,  the  fall  amounted  upon  the  whole  to  fifteen 
feet,  upon  a  length  of  200  yards,  it  might  be  more  convenient  to  lead  the  whole  ftream  in 
a  wooden  trough  fupported  upon  pofts,  with  a  flight  declivity,  to  the  wheel  near  the  lower 
end  of  the  current ;  or  in  other  circumftances,  according  to  the  face  of  the  land,  the  work 
might  prove  cheaper  or  more  durable  if  the  wheel  were  placed  near  the  upper  end  of  the 
ftream,  and  the  channel  funk  fo  as  ]to  convey  away  the  tail  water  with  no  more  fall  than 
fliould  be  neceflary  for  that  purpofe.     In  this  cafe  It  is  obvious  that  the  fall  muft  be  afcer- 

'*  Courfe  of  Leftures,  ii.  49S,  505,  536..  f  Reports,!.  216.  J  Ibid.  i.  323. 

§  He  clfewhere  (ibid.  p.  229.)  rates  an  horfe  at  250  hogfheads,  ten  feet  high,  in  an  hour ;  but  I  prefer  the 
ideduflion  in  the  text. 

6  tained 


Eafy  Method  of  LtvcU'tng,  '  467 

tahied  by  the  operation  of  levelling,  and  not  by  computation  as  In  our  former  fuppofition. 
This  operation  is  eafy,  and  may  be  performed  upon  fuch  fliort  diftances  with  fufficient  ac- 
curacy, with  a  carpenter's  fquare  and  a  ftafF. 

For  this  purpofe  it  will  be  neceffary  to  drive  a  pin  into  the  handle,  or  thickeft  part  of- 
the  fquare,  near  the  corner,  upon  the  flat  fide.  A  line  muft  be  drawn  from  the  pin,  pa- 
rallel to  the  edge  of  this  handle,  and  a  looped  thread  fupporting  a  fmall  weight  muft  be 
hung  upon  the  pin.  In  this  fituation  the  inilrua.ent  is  ready  for  taking  levels.  For  if  it 
be  held  in  fuch  a  pofition  that  the  plumb  line  may  cover  the  line  drawn  from  the  pin,  the 
blade  will  lie  horizontal,  and  by  looking  along  its  upper  edge  the  eye  will  be  direclcd  to 
fome  objeft  on  the  fame  level  with  itfclf.  Let  the  obferver  provide  himfelf  with  a  (lafF 
five  or  fix  feet  long  ;  which,  if  divided  into  feet  and  inches,  will  be  the  more  ufeful. 
This  is  to  be  pitched  at  or  near  the  lower  end  of  the  ftream,'  and  againft  it  the  obferver 
is  to  prefs  the  handle  of  his  fquare,  which  may  be  conveniently  done  by  grafping  both 
it  and  the  ftafF  together  in  the  fame  hand.  Then,  holding  the  apparatus  fo  that  the  plumb 
line  may  lie  fair,  he  is  to  direiS  the  blade  of  the  fquare  to  fome  ftone  or  other  remarkable 
obje£l;  higher  up  the  ftream  ;  for  which  purpofe  it  will  be  neceflary  to  Aide  the  handle  of 
the  fquare  up  or  down  the  ftafF  till  the  pofitions  are  accurately  obtained  ;  that  is  to  fay, 
till  the  blade  points  fairly  to  the  obje£l  at  the  fame  time  that  the  plumb  line  denotes  that" 
the  blade  is  level.  When  this  is  done,  a  memorandum  muft  be  taken  of  the  feet  and- 
inches  from  the  bottom  of  the  ftaff  to  the  upper  edge  of  the  blade,  and  the  obferver  muft 
proceed  to  the  ftone  or  objefl  to  which  his  fight  was  dire£led,  and,  planting  his  ftaflF  there, 
repeat  the  fame  operation  with  regard  to  fome  other  objecl  ftill  higher  up  the  ftream,  and 
again  note  down  the  feet  and  inches  obferved  upon  the  fl;afF.  This  procefs  continued 
will,  by  a  few  reiterations,  bring  him  to  the  upper  extreme  of  the  water  which  we  fup- 
pofe  to  be  within  his  grounds  or  power.  The  fum  of  all  the  meafures  taken  upon  the  ftafF 
is  the  difference  of  level  or  whole  fall  of  the  water.  The  quantity  of  water  in  cubic  feet 
may  be  afcertained  by  either  of  the  means  before  mentioned ;  or,  if  the  ftream  be  very 
fmall,  it  may  aflually  be  dammed,  and  meafured  off"  with  two  tubs  or  meafures,  of  as 
large  a  fize  as  can  conveniently  be  managed. 

I  fhould  be  inclined  to  apologize  to  fuch  of  my  readers  as-  are  intimately  acquainted 
with  thefe  fubjefts,  for  the  minutenefs  of  detail  into  which  I  have  entered,  if  I  were  not 
alFured  that  they  will  be  the  firft  to  perceive,,  that  many  individuals  who  pofFefs  beneficiat 
ftreams  are  totally  uninformed  of  their  value,  or  of  the  means  of  determining  the  fame. 

(To  be  continued.) 


IX. 

Enquirits  c.oncer.ning  ihe  Tnvention  and  Praclice  of  the  Art  of  Hat  making. 

To  Mr.  NICHOLSON. 
SIR,  Nevvcaftle,  15th  Dec.  1798.. 

OUR  Publication  being  open  to  enquiries  relative  to  the  advancement  of  manufac- 
tures, as  well  as  the  fcienees,  will  you  favour  me  with  a  place  for  the  following  queries,. 


4^5  ArtofHat-tnalwg.'-^ChemicalDetonattotis, 

■on  a  bufinefs  but  little  known  ?  And  probably,  amongft  your  fubfcribers,  tbey  may  be 
anfwered  through  the  fame  medium. — How,  and  at  what  time,  was  hat-making  invented, 
and  by  whom  ? — Were  there  ever  any  engines  made  ufe  of  in  that  bufinefs  ? — Are  there 
any  at  prefent  ?  And  if  fo,  in  what  part  of  the  country  arc  they  made  ufe  of?  And  how 
far  do  they  go  in  the  procefs  ? — Are  there  any  machines  for  the  cutting  of  hare,  rabbit, 
or  beaver  (kins  ?  And  if  any,  where  are  they  worked  ? — Your  inferting  the  above  in  your 

next  number  will  oblige,  Sir,  yours, 

N.  L. 

There  is  no  mention  made  of  the  above,  either  in  the  Tranfa£lion3  of  the  Royal  Society 
of  London,  or  in  Beckman's  Hiftory  of  Inventions. 


THE  above  did  not  come  to  hand  early  enough  for  me  to  make  any  enquiries  refpe£t- 
ing  the  invention,  hiftory,  and  practice  of  the  art  of  hat-making.  Refearches  of  the  kind 
pointed  out  by  this  correfpondent  are  peculiarly  adapted  to  the  views  and  intention  of  a 
Journal  of  the  Arts ;  and  I  hope  he  will  not  be  difappointed  in  his  expeftations  from 
others  of  my  readers,  whofe  purfuits  may  have  enabled  them  to  throw  light  upon  the 
fubjeft.  At  all  events,  I  fliall  certainly  have  fome  information  to  communicate  in  the 
ijext  number,  which,  for  want  of  time,  I  cannot  at  prefenc  arrange  and  digeft. 

W.  N. 


X. 

New  Obfervations  on  the  Method  of  producing  very  loud  Fulminations  with  various  Bodies^  by 
Means  ofPhofphorus^'.     £y  Qii.  BrvgnaTELLI. 

J.  WAS  aware  that  the  oxygenated  muriate  of  potafh  produces  efFefts  fuperior  to  nitre, 
when  mixed  with  charcoal  and  fulphur  and  converted  into  gunpowder ;  that  it  detonates 
by  percuffion  or  trituration  with  a  great  number  of  combuftible  fubftances;  but  I  did  not 
cxpeft  to  produce  effects  much  more  confiderable  by  ufing  the  fimple  nitrates,  and  even 
the  metallic  oxides  mixed  with  phofphorus  and  ftruck  with  a  hammer. 

Experiment  1.  I  took  a  gros  of  the  cryftallized  nitrate  of  fdver,  which  I  placed  on  an 
heavy  anvil,  and  laid  a  very  thin  flice  of  phofphorus  in  the  midft  of  the  cryftals.  The  tem- 
perature of  the  atmofpbere  during  thefe  experiments  was  not  higher  than  6°  above  the 
zero  of  Reaumur's  thermometer.  The  materials  being  thus  difpofed,  I  ftruck  the  mixture 
rather  fmartly  with  a  hammer.  The  confequence  was  one  of  the  moft  terrible  detonations 
I  everwitnefi'ed,  which  {hook  the  anvil  and  its  wooden  fupport.  Streaks  of  filver  were  ob- 
served upon  the  anvil  five  or  fix  lines  in  length.  One  of  the  edges  of  the  hammer  was 
bended  and  turned  upwards.  I  was  perfeQly  ftunned,  and  my  clothes  were  torn  in  various 
places. 

••Tranflated  by  Van  Moiis  from  the  Italian  manufcrlpt  of  the  author  into  French,  and  inferted  in  the  Anna- 
Je«  de  Chimie,  xxvli.  ji. ;  from  which  work  the  prefent  tranfiation  is  made. 

^  I  have 


I  have  frequently  repeated  the  Cimc  experiment,  even  in  my  ledlures;  and  though  I  ope- 
rated with  no  more  than  a  few  grains  of  the  fait,  tlie  noife  of  the  explofion  was  never  kfs 
than  that  of  a  mufquet. 

The  lapis  infernalis  has  nearly  theYame  efFecl  as  the  nitrate  of  filver. 

lixperimcut  2.  I  placed  on  an  anvil  a  pinch  of  the  oxygenated  muriate  of  potafh  with  a 
fmall  portion  of  phofphorus,  and  flvuck  the  mixture  with  a  hammer.  The  detonation  was 
cxcellivcly  ftrong. 

Eypr/nncni  3.  The  dry  nitrate  of  bifmuth  detonated  very  (Irongly.  The  fame  c^zQi 
was  produced  v.-ith  all  the  metallic  nitrates  which  were  to  be  found  in  the  laboratory,  and 
paniculaily  with  the  nitrate  of  tin. 

Expi-rivient  4.  I  repeated  the  fame  experiment  with  the  fufed  nitrate  of  mercury,  of 
wLiih  I  put  fix  grains  with  a  fmall  quantity  of  phofphorus  on  an  anvil,  and  ftruck  them 
with  a  hammer.  The  phofphorus  finiply  took  fire,  without  producing  any  noife  :  but 
when  the  hammer  was  flightly  heated,  the  fame  mixture  detonated  with  a  fliocking  noife. 
A  Iter  the  fulmination  the  mercury  was  found  reduced,  having,  as  It  were,  filvered  the  an- 
vil in  very  brilliant  radiations. 

■  Experhnevt  5.  I  afterwards  tried  the  alkaline  nitrates,  particularly  that  of  potafh.  "When 
a  fmall  flicc  of  phofphorus  was  laid  on  a  pinch  of  nitre  and  ftruck  with  a  cold  hammer,  no 
fulmination  was  produced  eve4r  by  repeated  blows;  but  having  flightly  heated  the  ham- 
mer, in  order  that  the  affinities  might  aft  more  decifively,  the  very  firR  blow  produced  a 
very  loud  fulmination,  incomparably  ftronger  than  that  of  gunpowder. 

Experiment  6.  I  obtained  no  fulmination  or  detonation  with  the  fulphates  of  ammine, 
of  copper,  or  of  iron  ftruck  with  phofphorus  in  the  before-mentioned  manner,  though  I 
heated  the  hammer  more  than  ufual. 

Experiment  7.  Neither  did  1  obtain  any  fulmination  from  the  fimple  muriate  of  filter, 
commonly  called  luna  cornea,  by  the  fame  treatment  with  phofphorus. 

Experiment  8.  I  likewlfe  tried  the  oxygenated  muriate  of  filver,  obtained  by  decern- 
pofii?g  the  nitrate  of  filver  by  the  oxygenated  muriatic  acid.  A  pinch  of  this  fait  (with 
phofphorus),  flruck  with  a  warmed  hammer,  produced  a  much  weaker  fulmination  than 
was  obtained  with  the  cryftallized  or  fufed  nitrate  of  filver,  or  the  other  falts  before  men- 
tioned. The  oxygenated  muriate  of  mercury,  treated  in  the  fame  manner,  afforded  a  yery 
weak  detonation.  '  1 

Experihtents  9  and  10.  I  endeavoured  to  produce  fulminations  with  the  metallic  oxydes 
Seated  with  phofphorus.  Thofe  of  manganefe,  of  zinc,  of  copper,  of  iron,  of  antimony, 
and  of  lead,  produced  no  eftcft,  even  when  ftruck  with  the  hammer  confiderably  heated  j 
but  I  obtained  fulminations  with  the  yellov,'  oxyde  of  mercury  (turbith  mineral)  and  the 
grey  oxyde  of  the  fame  metal. 

Turbith  mineral  does  not  fulminate  in  contatT:  with  phofphorus  when  it  is  pulverifed.' 
It  mud  be  in  a  lump  to  produce  this  efFed.  The  fame  thing  happens  with  regard  to  the 
grey  oxyde  of  mercury  by  the  nitric  acid,  except  that  the  fulmination  is  ftronger. 

Experiments  11  and  12.  I  was  curious  to  afcertain  whether  I  ftiould  obtain  Cmilar  ful- 
minations with  the  falts  before  mentioned,  by  fubftituting  another  acldifiable  combuftible 
fubftance  inftead  of  phofphorus  •,  as,  for  example,  fulphvir  and  charcoal. 

I  -accordingly  took  nine  grains  of  lapis  infernalis  and  three  grains  of  pulverifed  fulphiif . 
Vol..  II.— Jan.  1799.  3  P  \S'hich 


^yo  i^eiv  Experiments  on  Chemical  Detonation. 

which  I  ftruck  with  the  cold  hammer.  The  fulpliur  took  fire  without  affording  any  nolfe  5 
but,  when  the  hammer  was  ufcd  hot,  a  detonation  was  heard,  and  rays  of  filver  appeared 
on  the  anvil. 

Having  repeated  the  fame  e>;periment  with  lapis  infernalis  and  charcoal,  I  could  pro- 
duce no  more  than  a  very  dull  detonation,  though  the  hammer  was  well  heated. 

Experiment  13.  I  took  feveral  of  the  falts  which  had  fulminated  by  the  flroke,  and  threw 
them,  together  with  the  phofphorus,  into  the  liquid  o?sygenatcd  muriatic  acid  ;  but  no  de- 
tonation was  pioduced.  In  an  atmofpherc  of  the  gas  of  the  fame  acid,  the  fulminating 
mixtures  burned  with  a  flight  crepitation,  fimilar  to  that  which  is  excited  by  phofphorus 

alone. 

Experiment  14.  I  wrapped  men;  of  thefe  detonated  mixtures  in  fmall  pieces  of  paper, 
and  threw  them  one  after  the  other  into  a  red-hot  crucible.  They  burned  with  a  very 
lively  flame,  bin  did  not  fulminate  nor  detonate. 

Conclusion. 

ifl.  THE  nitrate  of  fvlver,  whether  cryftallized  or  fufcd,  fulminates  when  (Iruck  with  x 
Jiammer,  together  with  phofphorus,  even  at  a  low  temperature.  Exp.  i. — All  the  falts  of 
filvcr  do  not  fulminate  equally,  nor  in  the  fame  manner.    Exp.  7. 

ad.  Mod  of  the  metallic  nitrates  fulminate  with  phofphorus.    Exp.  3  .ind  4. 

3d.  Common  nitre,  of  which  the  fulminating  property  was  before  known,  in  its  mixture 
with  various  combufliblef,  elevated  to  a  certain  temperature,  or  put  into  contact  with  an 
inflamed  body,  as  in  gunpowder  or  fulminating  powder,  is  now  found  to  detonate  with 
phofphorus  alone.    Exp.  5. 

4th.  1  hofe  falts  into  which  the  nitric  acid  has  not  entered  as  a  component  part  do  not 
fulminate. 

5th.  The  oxygenated  muriates  of  pofafh,  of  filver,  and  of  ir.ercury,  fulminate  with  phof- 
phorus, but  the  latter  with  much  iefs  elFed  than  many  other  falts.     E  p.  8  and  2. 

6th.  The  falts  are  not  the  only  bodies  which  fulminate  with  pliofphorus  :  feveral  me- 
tallic oxydes  have  the  fame  property.     Exp.  9  and  10. 

7th  Phofphorus  likewife  is  not  the  only  acidifiable  and  folid  combuflible  matter  capable 
of  producing  fulminations.  Charcoal  produces  the  fame  efFe6t  at  a  more  elevated  tempa- 
lature.     Exp.  1 1  and  12. 

,  8th.  '^rhofe  lubftances  which  fulminate  with  phofphorus  produce  no  efFe£c  when  thro\V^ 
into  the  liquid  oxyg  nated  mjiriatic  acid.  E.xp.  13.— Neither  do  they  fulminate  when  ex- 
pofed  together  with  phofphorus  to  an  elevated  temperature.  Exp.  14. — The  blow  of  the 
hammer  is  neceflary  to  throw  the  component  parts  of  thefe  bodies  into  a  ft.ate  of  ofcilla-. 
tion,  in  order  to  determine  the  afliuities  withefFed. 


ADDITION  BT    VAN    MONS. 
THE  fafts  obfesved  by  the  learned  editor  of  the  Italian  Annals  of  Chemiftry  appeared 
too  curious  ai  d  important  for  me  to  lofe  any  time  in  repeating  his  experiments.     My  fuc- 
ceCs  was  as  follows ; 


Tiie 


New  Exptriments  on  Chemical  Deiofiatiof..  47 1. 

The  cryftallifcd  nitrate  of  filver  detonated  very  ftrongly,  emitting  only  a  weak  flame. 
T  he  filrer  was  reduced  to  the  flate  of  a  blackifli  oxydc. 

Lapis  infernalis  alfo  detcnatcd,  but  much  more  weakly.  The  metal  was  completely^ 
Tcduced. 

The  nitrate  of  tin  fulminated  with  confiderable  ftrength. 

The  fufed  nitrate  of  mercury  produced  a  ftrong  efi'cft. 

The  different -oxydes  tried  by  Brugnatelli,  that  of  manganefe  excepted,  produced  no 
noife  by  frlftion;  and  the  detonations  undpr  the  ftroke  were  at  leaft  doubtfuL  The  oxydes 
were  all  in  part  reduced^  and  the  mixtures  burned  in  a  lively  manner,  throwing  out  ignited 
fparks  to  a  diftance  ;  but  the  phofphorus  alone,  after  three  or  four  llrokes  with  the  ham- 
mer, exhibited  the  fame  appearance. 

The  oxygenated  muriate  of  mercury  afforded  perceptible  marks  of  detonation. 

I  produced  thefe  feveral  fulminations  without  heating  the  hammer  for  any  one  of  them. 
Friftion,  or  a  few  flight  previous  blows,  heat  the  materials  fufSciently  to  cau!"e  the  efiecl.  to 
take  place  with  the  lafl  fmart  blow. 

I  tried  a  great  number  of  times  to  make  the  cxperijiieiit  with  fulphur  and  lapis  infernalis. 
In  fome  inflances  I  rubbed  the  two  fubltances  together  with  all  my  force  in  iron  or  marble 
mortars,  and  in  others  I  ftruck  them  with  a  heated  hammer;  but  I  did  not  obtain  the  moft 
feeble  detonation.  The  matter  itfelf  did  not  even  take  fire,  excepting  when  I  flruck  it 
fmartly  in  an  iron  mortar  flrongly  heated  with  a  pcflle  equally  hot.  I  was  not  more  for- 
tunate with  charcoal.  Similar  experiments,  which  I  have  fmce  tried  with  various  other 
I'ubllances,  afforded  me  the  following  refults : 

The  nitrate  of  gold  by  evaporation  produced  a  louder  detonation  than  is  afforded  by  the 
oxygenated  muriates  of  alkali.  The  marble  mortar  in  which  I  made  the  experiment  was 
covered  with  fmall  particles  of  exceffively  thin  plates  of  reduced  gold.  The  metal  feemed 
to  have  undergone  a  very  liquid  fufion. 

The  muriate  of  mercury  detonated  with  a  force  at  leafl  equal  to  that  of  the  nitrate  of 
gold.     The  metal  was  almoft  entirely  diffipated. 

The  nitrate  of  lead  produced  a  weaker  detonation  than  the  foregoing.  The  metal  was 
found  reduced  to  the  ftate  of  black  oxyde. 

The  oxygenated  muriates  of  antimony,  zinc,  and  tin,  produced  a  much  weaker  effeft.  ■  I 
fuccceded,  however,  once  in  producing  a  very  flrong  and  inflantaneous  detonation  with  the 
firft  of  thefe  falts. 

The  oxydes  of  gold,  filver,  and  mercury,  by  fire,  were  found  to  occiipv  the  firfl:  rank 
among  the  fulminating  fubftances.  The  oxygenated  muriate  of  potafli  does  not  aflbrd 
cffeffs  equally  conlTant  with  thofe  of  the  oxydes. 

The  oxyde  of  lead,  in  its  different  degrees  of  oxydatlon,  afforded  in  no  inflancc  any  ap- 
pearance but  that  of  inflammation. 

I  formerly  exhibited  in  my  public  leiSlnres  the  detonation  which  may  be  produced  by 
percuffion  in  a  mixture  of  the  nitrate  of  potafh  and  phofphorus.  I  had  even  produced  ex- 
plofions  fufficiently  violent  to  induce  the  audience  to  fuppofe  that  I  operated  with  the  oxy- 
genated muriate.  I  fubmltted  the  nitrate  of  ammoniac  to  the  fame  treatment,  and  pro- 
thjced  a  detonation  fo  terrible  that  it  (liook  the  door»t>f  my  laboratory, 

3  P  ^'  Tm. 


47  2  ^(10  Experiments  on  Chemical  DiUnctloii, 

The  nitrates  of  barytes,  of  ftrontian,  and  of  magnefia,  by  deficcation,  detonateJ  with 
nearly  the  fame  force  as  the  nitrate  of  potafh. 

I  had  ftlll  remaining  five  grains  of  the  oxygenated  muriate  of  ammoniac,  of  which  I  took, 
the  half,  with  about  four  grains  of  phofphorus.  I  (lightly  cruflied  thefe  two  fubftances, 
with  the  intention  of  mixing  them  together,  wlien  a  detonation  fo  terrible  was  heard  that 
the  whole  houfc  was  alarmed.  The  phofphorus  was  for  the  moll  part  thrown  upon  mv 
hat,  which  it  burned  for  a  long  tine  before  I  perceived  it.  The  violence  of  the  blow  caufed 
the  hammer  to  fly  out  of  my  hands.  I  very  diftindly  felt  it  raifed  by  the  expanfion  of 
the  gafes.  The  other  half  of  the  oxygenated  muriate  of  ammoniac  was  placed  alone  upcr.i 
the  bottom  of  an  inverted  iron  moytar,  and  flruck  rather  brifiily  with  the  cold  hammer.  The 
hrft  blow  caufed  it  to  detonate,  but  no  light  was  difengaged.  I  regretted  that  no  more  of 
this  fait  remained  to  make  the  experiment  with  fulphur  and  charcoal. 

I  alfo  (truck  the  nitrate  of  ammoiiiac  alone.  The  fourth  blow  caufed  it  to  fulminate,  t 
fay  it  fulminated,  becaufe  the  detonation  was  accompanied  with  a  difengagement  of  light. 

I  obtained  an  effeft  equally  confiderable  from  the  white  nitrate  of  mercury  and  ammo - 
niac.  I  think  that  all  the  nitro-ammoniacal  triple  falts  will  detonate  more  or  lefs  (Irongiy 
with  phofphorus. 

I  was  defirous  of  trying  the  folid  oxygenated  muriatic  acid  ;  for  which  purpofe  I  caufed 
this  acid  to  cryftalHze  by  artificial  cold.  A  few  cryftals  of  this  acid  were  put  together, 
with  a  fmall  piece  of  phofphorus,  upon  an  iron  mortar  placed  in  a  cooling  mixture.  When 
thefe  were  llruck  with  a  hamm'er,  a  dull  detonation  was  heard  at  the  fixth  or  feventh  blow. 
The  fufed  acid  was  projedled  to  a  diflance. 

I  repeated  a  great  number  of  thefe  experiments  with  pyrophorl  and  the  phofphori  called 
artificial  carefully  prepared;  and  in  almoft  every  cafe  I  obtained  a  detonation.     I  fliall  de-  . 
fcribe  my  experiments  on  thefe  lingular  inflammable  preparations  in  a  feparate  article. 

Whenever  I  flruck  the  before-mentioned  mixtures  with  a  heated  hammer,  I  always  ob- 
tained a  weaker  detonation,  at  the  fame  time  that  the  inflammation  was  (Ironger  ;  and  when 
the  hammer  was  too  hot,  no  detonation  or  noife  was  produced.  This  obfervation  I  had  al- 
ready made  with  the  oxygenated  muriate  of  potafh ;  and  it  appears  to  me  to  explain  the 
phenomena  of  detonation.  The  blow  with  the  cold  apparatus,  by  ftrongly  comprefling 
the  matter,  and  perhaps  exciting  fome  heat,  produces  a  partial  combuflion  of  the  phofpho- 
rus, and  confequently  engages  only  part  of  the  oxygen  of  which  the  other  portion  aflTumes 
the  elaftlc  (late,  and  produces  the  noife  of  the  detonation.  At  a  very  elevated  temperature 
the  eflfcfts  are  not  altogether  the  fame.  All  the  oxygen  is  at  once  employed  to  burn  the 
combuftible,  whence  the  inflammation  is  the  ftrongelt,  and  no  detonation  takes  place.  In 
fa£t  it  is  obfervable,  that  the  more  fudden  and  fonorous  the  noife,  the  lefs  is  the  develope- 
ment  of  fire ;  and  the  contrary.  To  this  principle  alfo  is  referable  the  obferration  made  by 
Brugnatelli,  which  I  have  found  to  be  true,  that  the  oxygenating  body  muft  in  fome  in- 
ftances  po(rcfs  the  form  of  a  lump  to  obtain  the  efFe£t ;  becaufe  it  applies  too  extenfively 
to  the  combuftible  matter  when  powdered. 

Thefe  experiments  fucceed  much  better  by  ,fri£lIon  than  by  a  blow,  and  the  eiFe£l$ 
take  place  more  readily  upon  a  rough  than  a  fmooth  body.  I  ufually  place  the  two  fub- 
ftances  on  the  bottom  of  an  inverted  marble  mortar,  which  is  left  rough  from  the  faw. 

'  Upon 


Chem'ual  Dttonat'wn.'— Tunnel  beneath  the  Tkimes.  473' 

Upon  tliefe  I  prefs  the  face  of  an  iron  hammer,  holding  the  handle  with  the  left  hand,  and 
fuddenly  Aide  the  hammer  forward  fo  as  to  produce  a  kind  of  (hock.  In  this  manner  the 
tletonation  or  noife  is  iikewife  more  diflintt,  and  its  force  more  eafdy  determined.  Simple 
comprcffion  produces  the  detonation  in  many  cafes. 

I  think  it  proper  to  warn  thofe  who  are  not  familiar  with  experiments  of  this  kind, 
that  when  the  operation  is  performed  with  more  than  a  grain  and  a  half,  or  at  moft  two 
grains  of  phofphorus,  there  will  be  danger  of  burning  their  hands  or  clothes  by  the  exccfs 
of  this  combuftible,  which  flies  off  in  a  burning-ftate. 

I  cannot  finifh  this  article  without  reftoiing  to  its  true  proprietor  the  portion  of  honour 
which  is  due  to  the  difcoverer  of  the  detonating  property  of  the  oxygenated  muriate  by 
percuffion  or  flrong  friclion,  which  Citizen  Fourcioy  has  attributed  to  me  in  the  Me- 
moir *  he  has  communicated  to  the  National  Inftitute,  no  doubt  in  confequence  of  my 
having  mentioned  this  phenomenon  in  my  edition  of  the  Philofophy  of  Chemiftry,  under 
the  article  of  Oxygenated  Muriates.  Profeflbr  V/urzer,  of  Bonn,  was  the  firft  who  ob- 
ferved  this  faft,  by  triturating  with  fome  force,  in  a  mortar,  a  mixture,  fcarcely  weighing 
a  grain  and  a  half,  of  three  parts  of  the  oxygenated  muriite  of  foda  and  one  part  of 
fulphur.  He  obtained  a  detonation  which  rendered  him  deaf  for  feveraldays.  See  Crell'i 
Chemical  Annals  for  the  year  1792,  vol.  ii.  page  402, 


TUNNEL   BENEATH  THE  THAMES. 

Reports,  with  Plans,  Se£lions,  &c.  of  the  propofed  Dry  Tunnel  or  Paffage  from  Gravef- 
end  in  Kent  to  Tilbury  in  JilTex,  demonftrating  its  Practicability,  and  great  Importance 
to  the  two  Counties  and  to  the  Nation  at  large  ;  alfo,  on  a  Canal  from  near  Gravefend 
to  Stroud,  with  fome  Mifcellaneous  and  Praftical  Obfervations.  By  R.  Dodd,  En- 
gineer. Quarto.  28  pages,  with  3  plates:  viz.  1.  Plan  and  Se£lions  of  the  propofed 
Tunnel.  2.  A  View  of  Gravefend  and  Tilbury,  with  the  Section  of  the  River,  (hew- 
ing the  Strata  and  Depth  of  Water:  and,  3.  A  Map  of  the  Country  within  twenty  Mile* 
of  Gravefend.     London,  printed  for  J.  Taylor,  1 798. 

kJOME  account  of  this  undertaking  was  given  in  this  Journal  a  few  months  ago. 
(II.  239.)  The  prefent  Reports  will  afford  fatisfadory  information  of  its  detail  and 
progrefs,  and  the  public  will  hear  with  pleafure  that  it  is  likely  to  be  carried  into 
effeft. 

In  the  month  of  May  1798,  Mr.  DoUd  circulated  an  Introduftory  Report  or  Addrefs 
to  the  Nohility,  Gentry,  &c.  of  Effex  and  Kent,  in  which  he  ftates  that  the.  extended  fcale 
of  commerce  on  the  liver  Thames  forbids  the  conftru£tion  of  a  bridge  at  Gravefend  •  but 
that  the  pradlice  of  making  paffages,  tunnels,  or  drifts  under  rivers  has  been  adopted  to  a 
great  extent  in  various  parts  of  the  kingdom  ;  namely,  at  the-coal  works  under  the  rivers 
Tyne  and  Wear,  and  at  Whitehaven  under  the  very  ocean  ;  that  a  tunnel  is  adlually  in- 
tended to  be  made  under  the  mouth  of  the  river  Tyne,  to  anfwer  the  purpofes  of  a  bridge 
for  carriages  and  paffengers ; — that  the  meafure  now  propofed  will  favc  a  circuit  of  near 

*  Pliilofophical  Journal,  I.  16*, 
6  fifty 


.474  Reports  and  Proceedings  cancer  tit  ng  the  fultcrrcmeom 

'fifty  miles  to  carriages  pnflTmg  from  one  county  to  the  other  \  and  that  the  fituation  at  or 
•near  Gravefend  is  peculiarly  eligible  from  its  natural  facilities,  as  the  greateft  part  of  k\\c 
ground  to  be  pafTed  tlirough  is  chalk.  Thefe  obfervations  are  followed  by  the  propofil 
and  eftimate  vvhiih  have  already  been  given  at  the  page  of  our  Journal  lad  quoted.  Mr. 
Dodd  obferve€  that  12I.  per  running  yard  nuift  be  confidered  as  a  handfome  allowance, 
•fince  it  is  a  fact,  tiiat  fome  of  the  mplT;  confiderable  tunnels  in  this  kingdom  on  a  fcale  of 
nineteen  fettby  feventecn,  which  is  larger  than  the  tunnel  at  prefent  recommended,  have 
been  executed  at  that  price. 

On  the  iSthof  Jt^ly  I7c>8,  a  meeting  was  held  in  the  Town  Hall  of  Gravefend,  the 
Earl  of  Darnley  in  tlie  chair  ;  when  it  was  refolved,  That  there  being  no  reafcn  to  doubt 
the  pradlicabilify  of  fo  deGrable  a  tneafure,  the  co-operation  of  government,  the  aflent  of 
the  neighbouring  lar.d  Qwners,  or  the  willingnefs  of  the  public  to  fubfcribe  to  its  accom- 
plifliment,  the  opinion  of  the  meeting  was,  that  transferable  fhares  of  lool.  each  would 
afford  the  bed  meaas"  of  efiefl iiig  it ;  and  that  a  I'libfcription  fliould  be  opened  at  the  office 
of  Meflrs.  Evans  and  Son,  at  Gravefend,  for  its  fupport  and  encouragement. 

In  the  report  and  efliniate  which  the  engineer  prefented  to  this  meeting,  he  flates,  that 
from  the  a£lual  furvey  he  finds  no  reafon  to  add  to  the  former  eftimate,  but  rather  to  abate 
fome\^hat  more  than  30C0I.  on  account  of  the  excellent  chiilk  which  lie  finds  will  be  af- 
forded at  the  mofl  eligible  place  for  the  CAcavation.  The  deviation  from  an  horizontal 
line  of  the  tunnel,  which  pafles  at  about  tliirty  feet  below  the  bed  of  the  river,  will  be 
four  inches  in  the  yard.  Several  military  and  commercial  advantages  of  the  undertaking 
^re  likewife  clearly  ftated,  and  an  eftimate  given  of  the  coft  of  a  twelve  feet  tunnel,  ad- 
mitting carriages  to  pafs  only  one  way  at  a  time,  in  cafe  the  fixteen  feet  turmel  (liould  be 
thought  too  expenfive.  In  the  fubfequent  obfervations  the  author  enlarges  dill  more  upon 
the  fame  interefting  topics,  and  makes  a  comparifon  between  the  communication  by  tun- 
nels and  the  great  modern  improvement  of  iron  bridges,  which  lad  ereiSlioii  he  Ihcws  to 
be  much  lefs  durable,  and  more  liable  to  fpeedy  deftrudion  by  an  enemy,  than  the  tunnel. 
He  remarks,  that  the  dedruitive  eladic  fluids,  which  are  known  to  be  extricated  in  mines, 
■cannot  affeft  the  prefent  work  when  once  finiflied,  becaufe  of  the  clear  communication 
with  the  external  air  at  both  ends  ;  and  he  gives  fome  practical  remarks  on  the  difcovery  of 
inflammable  air  or  fire-damp,  which,  on  account  of  the  intercding  nature  of  the  fubjefl,  I 
lliall  here  tranfcribe. 

"  On  entering  any  excavation  under  ground,  where  this  fire-damp  is  fufpccled  to  He, 
the  candle  ought  to  be  held  in  the  left  hand  (the  fmaller  the  candle  the  more  to  be  de- 
pended upon),  and  the  flame  thereof  to  be  fliaded  by  the  right-hand  fingers  being  placed 
liorizontal,  and  on  a  level  with  the  top  of  the  flame  of  the  candle.  If  the  air  be  good,  and 
■  pcrfeflly  free  from  any  inflammable  air  or  hydrogen,  a  fmall  brown  top  or  pinnacle  is 
feen  on  the  top  of  the  flame,  the  fame  as  is  fcen  in  the  chamber  of  a  houfe;  but  on  ap- 
proaching the  real  fire-damp  airother  top  or  fpire  is  feen  of  a  blue  colour,  above  the  brown 
jud  defcribed  as  arifing  therefrom  ;  and  on  advancing  a  dep  or  two  forward  the  damp  is 
commonly  more  denfe,  and  confequently  the  appearances  over  the  candle  aflume  a  more 
feiious  afpe£l  by  the  brov,-n  fpire  or  fmall  top  beginning  to  difappear;  another  dep  per- 
haps reduces  it  altogether,  on  which  the  danger  commences  ;  and  the  fpire  or  top  fits  down 
altogether  blue  on  the  dame.     At  this  lad  dagc  it  Is  not  fafe  to  proceed  further  without 

great 


TunnelU  be  made  lencaththe  Thames  at  G.avefend.  475'. 

great  circumfpedion  joined  with  fteadincfs :  a  little  further  the  blue  top  is  feen  to  be 
more  perfea  and  denfe,  which  if  general  through  the  place,  all  lights  Ihcmld  be  extin- 
guifhed,  and  the  workmen  be  made  to  quit  the  place.  Perhaps  on  advancing:  a  very  little 
further  a  light  blue  bead  appears  to  circumfcribe  the  other  dark  blue,  as  if  approaching  to 
name,  and  having  a  more  than  ordinary  pointed  fpire  terminating  like  a  white  thread  ; 
and  the  danger  becomes  very  great  if  to  remain  any  time  in  this  pofitlon.  The  next  (lage 
fliews  the  fprents  to  have  taken  place,  which  fprents  are  fimiiar  to  thofe  produced  by 
fqueezing  the  oil  from  the  rind  of  a  lemon  into  the  flame  of  a  candle  :  at  this  period 
fometimes  has  been  obferved  a  fmall  bufhy  dark-coloured  cloud  hanging  over  the  top  of 
the  flame,  flill  more  and  more  attrasSing  the  fire  ;  when  in  an  indant  perhaps  after  this  laft 
obfervation  the  whole  appearance  expands  into  flames,  and  one  general  conflagration  takes 
place.  1  he  mifchief  which  enfues  is  in  proportion  to  the  accumulated  quantity  of  this 
pernicious  vapour;  which  if  great  flies  to  the  neareft  aperture  leading  to  the  atmofphere, 
being  about  eleven  times  lighter  than  common  air,  with  a  dreadful  explofion  and  extraor- 
dinary eruption.  But  in  cafe  tlie  faid  fire-damp  or  inflammable  air  be  mixed  with  flylh, 
or  black  damp,  thefe  appearances  are  fomewhat  varied  ;  and  by  being  mixed  with  a  very 
dark  brown  is  in  general  more  fafe. 

"  Black  damp  or  ftyth"  (doubtlefs  carbonic  acid,  or  hydro-carbonate)  "  which  arifes- 
in  mines  is  direflly  the  reverfe  of  inflammable  air  or  fire-damp  9  the  former  extinguifhes 
the  flame  of  a  candle  as  quickly  as  if  put  into  water  or  any  other  fluid  ;  the  other 
caufes  the  candle  to  burn  too  faft.  Ihis  flvth  or  black  damp  prevails  moft  where 
there  is  little  or  no  inflammable  air,  and  when-  the  due  circulation  of  atmofpheric  air  is 
iieglefted."  , 

,  It  was  of  elTential  confequence,  by  way  of  fliewing  the  praflicabiiity  of  the  prefent  urt-- 
dertaking,  that  Mr.  Dodd  fliould  imprefs  the  minds  of  his  employers  with  the  fad   that 
fuch  tunnels  had  been  made  with  fuccefs  on  a  much  larger  fcale.     For  this  purpofe  he  re- 
lates various  hillorical  matters,    befides  thofe  already  mentioned,  from  which  we  may 
notice,  that  the  earliefl  tunnel  for  inland  navigation  was  executed  by  M.  Riquet,  to  convey 
the  canal  of   Languedoc  through  a  mountain  near  Bezieres.     The  firfl  executed  in  this  • 
country  was  by  the  celebrated  Brindley  on  the  duke  of  Bridgewater's  canal  near   Man- 
chefter.     The  next  is  the  famous  tunnel  of  Hare  Caftle  Hill,  in  i)tafFordllnre,  by  the  fame 
engineer,  which  is  2880  yards  long,  and  palTes  through  a  variety  of  fttata,  quickfands,  &c. 
more  than  feventy  yards  below   the  furface  of  the  earth,  and  ferves  as  the  receptacle  for 
part  of  the  Grand  'Trunk  Canal.    The  tunnel  of  Sapcrton  is  two  miles  and  three  quarters,- 
long,  and  was  carried  through  two  miles  of  folid  rock.     Many  other  drifts  or  tunnels  have 
been  made  in  this  kingdom,  through  rocks  and  obftacles   of  various  kinds,  in  a  courfe  of 
time  and  at  expence  much  lefs  than  would  be  apprehended  by  perfons  unacquainted  with- 
•works  of  this  nature. 

Mr.  Dodd's  report  and  eflimate  on  the  projected  dry  tunnel  under  the  river  Tyne  con- 
tains illuitrations  and  argument  of  nearly  the  f;ime  import.  His  pamphlet  concludes  with 
a  propofal  for  an  inland  canal  from  the  Thames  near  Gravefcnd,  to  the  Medway  near 
Stroud.;  which,  by  a  (hort  courfe  of  about  fix  miles,  would  fave  the  circuitous  and  lefs 
certain  paflage  of  forty-feven.  miles  by  the  way  of  the  Nore.  The  peculiar  advantages  of 
this  cut  to  the  country  at  large,  and  to  the  government  edablifhments  on  thefc  rivers,  as  well; 
zi  the  nature  of  the  grouiKl  itfelf,.are  ftrongly  and  perfpjcuoufly  Hated, 


4'/''  Tunnel  hene<ith  the  Thames.— 'AL:  CcuivJrlght'j  P-iJon. 

The  kfl  public  meeting  on  the  former  bufinefs  was  held  at  th«  London  Tavern  on  the 
J4,t}i  of  laft  monih  (December) ;  when  it  appeared  by  the  Report  that  the  fubfcriptlons 
amounted  to  upwards  of  ten  thoufand  pounds.  '1  he  managing  committee  of  fubfcribcvs 
confills  of  the  Earl  of  Darnley,  Lord  fetrc,  the  Hon.  J.  T.  Towniliend,  M.  P.  the  Hon. 
Robert  P£tre,i^ir  William  Gearyj  Bart.  M.  P.,  Mr.  Aid.  Lufliington,  M.  P.,  John  J.  An- 
gerftein,  and  Claude  Scott,  Efqrs.  Lieut.  Col.  Twifs,  Royal  Engineers,  Capt.  Schank,  R.  N. 
'T,  Wootlruffe  Smith,  Efq  ,  John  R'lavor,  Efq ,  Geo.  Hawks,  Efq  ,  and  Benjamin 
Harrifon,  £fq. — Claude  Scott,  Efq.  is  Treafurer. 

The  undertaking  will  be  begun  and  carried  on  by  thofe  who  fliall  firfl  fubfcribe  to  the 
propofed  fliarea,  wi^ich  are  three  hundred  at  a  hundred  pounds  each  •,  but  the  a^^ual  work 
will  not  be  commenced  till  the  whole  fum  of  thirty  thoufand  pounds  fli.ill  have  been  fub- 
fcribed. 


A  fellow-labouier  in  the  caufe  of  fcience,  Mr.  A.  Tilioch,  objefts  totally  to  the  account 
'I  gave^'-'Mp*  Cartwright's  apparatus  for  rendering  the  plllous  of  fleam-engines  tight  by 
metallic  fittings,  at  page  365  of  the  prefent  volume.  y\s  the  whole  of  his  remarks  appear 
to  me  to  be  obvioufly  erroneous,  and  the  matter  is  before  the  public,  I  mull  be  excufed  from 
entering  into  controverfy.  He  will  himfelf  perhaps,  on  fccond  thoughts,  recollecl  that  a  cir- 
cle, even  though  in  diameter  equal  to  that  of  the  earth,  will  not  be  converted  into  a  triangle 
by  cutting  it  in  three  pieces  ;  and  that  it  is  abfurd  to  fuppofe  the  third  law  of  nature,  that 
eB'wn  and  ri-a£iion  are  equal  and  contrary.,  can  either  be  difpenfcd  wither  explained  away.  H<: 
will  then  probably  look  (not  to  the  vacuum,  but)  to  the  lower  plate  of  Mr.  Cartwright's 
pifton  for  the  re-aQion  ;  which,  by  means  of  the  pifton  rod  and  the  work  required  to  be 
<lone,  is  made  to  aft  beneath  the  moveable  pieces  of  the  apparatus,  while  the  fleam  preiTcs 
their  upper  furface  with  no  inconfiderable  force;  admitting  its  elafticity  to  be  equivalent  to  a 
Cngle  atmofphere  only:  a  force  fufTicient,  in  my apprehenfion,  to  prevent  ground  furfaces  from 
Aiding  freely,  if  at  all,  upon  each  other.  But,  as  we  are  all  liable  to  miflakes  in  new  pra£tical 
matters,  1  could  have  wilhed  that  Mr.  Tilioch  had  rcafoned  lefs  diflufely,  and  referred  at 
once  to  the  fa£ls.  If  it  be  true  that  there  was  a  fleam-engine  at  work  fix  months  ago, 
when  Mr,  T.  invited  the  public  to  infpe£l  it,  at  Mr.  Rowley's,  in  Cleveland-ftreet,  Mary- 
lebone*  j  or  if  he  can  bring  evidence  that  fuch  an  engine  has  been  at  work  for  any  cori- 
fiderable  part  of  the  fime  lince  he  publifhed  his  defcription,  and  that  the  facility  of  ope- 
ration, the  power,  and  the  durability  of  the  apparatus  are  fuch  as  he  conceives  them  to 
be ; — ^I  cannot  but  think  that  he  has,  unfortunately,  overlooked  his  beft  argument.  To  this 
argument,  if  ofFered,  1  mufl  grant  my  alTcnf,  and  I  beg  leave  to  allure  him  that  I  Ihall 
moll  readily  attend,  infpe£l,  and  report  concerning  this  engine,  if  he  or  the  invenpot  will 
give  me  the  opportunity,  without  in  the  leafl  regarding  whether  this  part  of  my  duty  to 
the  public  fliall  confirm  or  overthrow  thofe  opinions  which  the  prefent  flate  of  the  fadshas 
compelled  me  to  give. 

•  I  went  there  at  the  time,  and  faw  the  parts  of  a  fmall  model  or  engine,  which  was  not  at  work;  and, 
upon  late  enquiry,  I  underftand  there  is  none  there  at  prefent.  I  could  gain  ivo  informition  whether  there 
vvai  any  engine  ofthis  conllruftion  at  work,  or  in  progrefs,  at  any  other  place. 


■" 

1 

^ 

0 

IS^- 


FlulM.JoumalTiUUUZtttahfi  p.  Ijd. 


Jlariitw  JOilp. 


JOURNAL 


OF 


NATURAL   PHILOSOPHY,   CHEMISTRY, 


AND 


THE   ARTS. 


FEBRUARr    1799. 


ARTICLE  I. 
On  the  Corundum  Stone  from  Afta.     By  the  Right  Hon.  CHARLES  GrEP'ILLE,  F.  R.  S  *. 


H. 


Analyfi  cryftaUoriim,  tarn  cjufdem  quam  diverfae  figurae,  multum  lucis  fcientia  expeftat. 

Bergman,  Opufc.  de  Terra  Gemmarum. 


.  AVING  contributed  to  bring  into  notice  the  mineral  fubftance  from  the  Eaft-Indies, 
which  is  generally  called  adamantine  fpar,  I  beg  leave  to  lay  before  the  Royal  Society  the 
following  account  of  its  hiftory  and  Introduction, 

About  the  year  1 767,  or  1 768,  Mr.  William  Berry,  a  very  refpefkable  man,  and  an  emi- 
nent engraver  of  ftone,  at  Edinburgh,  received  from  Dr.  Anderfon,  of  Madras,  a  box  of 
cryftals,  with  information  of  their  being  the  material  ufed  by  the  natives  of  India  to  polifli 
cryftal,  and  all  gems  but  diamonds.  Mr.  Berry  found  that  they  cut  agate,  cornelian,  &c. 
but  in  his  minute  engraving  of  figures  upon  feals,  &e.  the  fuperior  hardnefs  of  the  diamond 
appeared  preferable  5  and  its  difpatch  compenfatcd  for  the  price :  the  cryftals  were  therefore 
laid  afide  as  curiofities.  Dr.  Black  afcertained  their  being  different  from  other  ftoncs  ob- 
ferved  in  Europe ;  and  their  hardnefs  attached  to  them  the  name  of  adamantine  fpar.  My 
friend,  Colonel  Cathcart,  fent  me  its  native  name.  Corundum,  from  India,  with  fome  fpecimens 
given  to  him  by  Dr.  Anderfon  in  1784,  which  I  diftributed  for  analyfis. 

When  the  native  name  was  obtained,  it  appeared  from  Dr.  Woodward's  catalogue  of 
foreign  foffils,  publiflied  about  the  year  17 19,  that  the  fame  fubftance  had  been  fent  to  him 
by  his  correfpondent  Mr.  Bulkley. 

In  his  firft  catalogue  of  foreign  foflils,  p.  6.  ^.  17.  "  Nella  corivindum  is  found  in  fields 
where  the  rice  grows  :  it  is  commonly  thrown  up  by  field  rats,  and  ofed,  as  we  do  emery,  to 
folifli  iron*" 

•  Philofophical  Tranfaftions,  179S,  p.  403. 

Vol.  II. — Feb.  1799.  3  CJ^  Page 


478  On  the  Corundum  Stone  from  Afia. 

Page  IT.7..  13.     "  '^ella  convlndum.  Fort  St.  George,  Mr.  Bulkley.     'Tis  a  talky  fpar," 
grey,  with  a  caft  of  green :  it  is  ufed  to  polifh  rubies  and  diamonds." 

In  Dr.  Woodward's  Additional  Catalogue  of  Foreign  Foflils,  publifhed  in  1725,  p.  6. 
^10.  "  Nella  corivendum  is  found  by  digging  at  the  foot,  or  bottom,  of  hills,  about  five 
hundred  miles  to  the  fouthward  of  this  place..  They  ufe  it  as  emery,  to  clean  arms,  &c.  it 
ferves  alfo  to  grind  rubies,  by  making  it  like  hard  cement,  by  the  help  of  ftick  lac  mixt  with 
it;  Eaft-India.  Mr.  Bulkley." — ^Thefe,  with  a  few  others  in  Woodward's  Catalogues,  are 
t!ie  only  inftances  by  which  any  author,  prior  to  1768,  appears  to  have  noticed  this  fubftance. 

This  information  being  unfatisfa£tory,  and  every  appearance  of  the  ftone  indicating  it  to 
be  part  of  a  ftratum,  I  wrote  repeatedly  to  friends  in  India,  to  afcertain,  if  poffible,  the  fitua- 
tion  of  the  rock,  and  if  near  the  fea,  to  fend  a  confiderable  quantity  as  ballafl:,  with  a  view 
of  applying  it  to  cut  and  polifli  granites,  porphyry,  and  other  ftones,  which  the  high  price  of 
cutting  and  polifliing  excluded  from  ufeful  or  ornamental  work.  But  my  inquiries  at" 
Madras  were  fruitlefs  :  by  fome  I  was.aflured  it  came  from  Guzarat.  From  Bombay  I  ob- 
tained no  fatisfadory  information.  At  laft,  in  the  year  1793,  I  obtained  a  fatisfadtory  ac- 
count. Sir  Charles  Oakley  was  difpofed  to  oblige  me  :  he  was  tlien  Governor  of  Madras  - 
and  his  fuccefs  is  due  to  the  aftivity  and  judgment  of  Mr.  Garrow. 

Mr.  Garrow  knew  how  difEcult  it  was  to  avoid  the  caufes  of  my  failure,  from  every 
Hindoo  being  occupied  by  the  duties  of  his  call ;  fcarcely  thinking  on  any  thing  elfe,  and 
wherever  his  interell  is  concerned,  being  fufpicious  and  referved.  Mr.. Garrow,  in  the  firft 
place,  afcertained  the  caft  conneded  with  corundum,  to  be  the  venders  of  glafs  bangles ;  that 
they  ufed  it  in  tlieir  bufinefs,  and  fold  it  to  all  other  cafts.  This  caft  of  natives  at  all  times 
liad  free  accefs  to  every  part  of  Tippoo's  country ;  nor  until  the  diftrids  about  Permetty 
■were  ceded  to.  the  Englifh,  could  it  be  procured  in  any  other  way.  Mr.  Garrow  depended 
■  on  his  perfonal  infpedion  ;  the  particulars  are  contained  in  tlie  following  letter  communi- 
cated to  me  by  Sir  Charles  Oakley. 

Sir  CHARLES  OAKLEY,  Bart. 

"  Sir^  Tritchinopoly,  loth  Nov.  1792. 

"  I  derived  fo  little  fatisfaftion  from  the  various  accounts  given  me  of  the  corundum, 
from  the  indifference  of  the  natives  to  every  fubjed  in  which  they  are  not  immediately  in- 
terefted,  that  I  refolved  to  afcertain  the  particulars  I  wifhed  to  know,'  on  the  fpot  where  the 
ftone  is  found.  The  glafs-men  agreed  in  one  material  circumftance,  that  the. place  was  not 
far  from  Permetty :  in  other  particulars  they  difagreed,  apparently  with  intention  to  miflead. 

"  It  is  near  a  fortnight  fince  I  difpatched  a  fervant  I  could  depend  on  to  Permetty,  with 
one  of  thefe  people,  who  on  his  arrival  there,  probably  through  fear  of  his  caft,  faid  he 
knew  no  farther.  My  fervant  perfevered,  and  informed  me-  he  had  found  tlie  place  I  wiflied 
to  lee.  ■-  ■  ■    •  ■  "--^ .' 

*'  I  arrived  at  Permetty,  by  the  route  of  Namcul,  the  6th ;  and  leai^rng'tRat  the  diftance 
to  the  fpot  was  about  3^  hours,  or  14  miles,  I  left  Permetty  in  time  to  arrive  there  about  fun- 
rife  the  next  morning.  At  this  time  no  perfon  but  my  fervant  was  prefent,  and  from  a  con- 
tinued excavation  at  different  depths,  from  6  to  16  feet,  in  appearance  like  a  water-courfe, 

.     „  ■      i    ■■     ..  -'    I  running 


On  the  Corundum  Stone  from  Afta.  4f^ 

filnning  in  length  about  a  mile  and  a  half  eaft  and  weft  over  the  brow  of  a  very  rifing  groand, 
I  faw  at  once  the  place  from  which  the  ftone  was  procured.  The  prodigious  extent  that 
at  different  times  appears  to  have  been  dug  up,  with  the  few  people  employed,  ftiews  that  it 
has  been  a  bufinefs  of  ages.  '         . .  - 

"  The  ground  on  which  the  vein  of  excavation  runs,  and  of  courfe  the  mineral,  commands 

,   one  of  the  fineft  and  moft  extenfive  profpe<fts  it  is  poffible  to  conceive.     The  furface  of 

the  ground  is  covered  with  innumerable  fine  alabafter  ftones,  and  a  variety  of  fmall  fhrubs, 

but  not  a  tree  fufEcient  to  flicker  my  palanquin.  .  ■,  ^,  J 

**  There  is  not  the  appearance  of  an  habitation  within  three  quarters  of  a  mile.  The 
neareft  village  is  called  Condraftra  Pollam.  In  this  village  are  about  30  fftiall  thatched 
houfes :  among  thefe  are  5  families,  who,  in  defcent  by  prefcriptive  right,  are  the^miners,  and 
dig  in  the  pits.  The  neareft  place  of  any  confequence  in  Rennel's  Map,  is  Caranel,  on  the 
fouth  fide  the  Cavery.  The  diftance  of  the  pits  from  the  river  is  above  four  miles  ;  but  the 
ground  between  prevents  its  being  feen  in  a  direft  line;  A  fine  view  of  the  river  is  feen  nestfe 
Erode ;  which  fort,  as  well  as  Sankerdroog,  are  plainly  vifible  with  the  naked  eye,  as  is  alfd 
the  Coimbitoor  country,  fouth  and  weft  of  die  river,  to  an  immenfe  extent. 

"  I  procured  at  Permetty  a  cadjan,  from  the  Bramin  manager  to  the  head  man  of  the 
Pollam';  which  on  my  arrival  at  the  pits  I  fent  to  him ;  and  foon  after  three  of  the  miners 
came  from  the  Pollam,  with  their  implements,  and  families  following  with  provifions.  As 
they  came  up  they  inquired  of  my  fervant  how  they  were  to  addrefs  me,  having  never  feen 
an  European  before. 

"  I  followed  them  into  a  pit  in  the  line  of  the  excavation,  above  14  feet  from  the  ground 
level.  The  inftrument  they  ufed  is  a  very  heavy  iron  crow,  ending  in  a  broad  point,  with 
a  ftraight  wooden  handle  clampt  with  iron.  The  foil  they  cut  through  is  of  different  colours, 
but  compofed  chiefly  of  a  gritty  granite ;  and  at  the  depth  of  feven  feet  are  layers  of  a 
fubftance  not  unlike  dried  pitch,  which  crumbles  into  fmall  flakes  when  taken  out.  With 
confiderable  labour  the  miners,  with  the  points  of  their  crows,  cut  out  feveral  pieces  of  the 
ftrata,  of  fome  pounds  weight  each ;  and  when  a  confiderable  quantity  was  broken  off,  it 
was  carried  up,  and  cruftied  to  pieces  with  great  force  by  the  iron  crow.  Among  thefc 
broken  lumps  the  corundum  ftone  is  found ;  but  in  many  of  the  pieces  there  was  nonju 
The  mode  of  getting  it,  made  it  difficult  to  get  any  with  the  ftratum  adhering  to  it ;  this, 
however,  after  feveral  trials,  I  obtained  very  perfedl,  and  ftiall  forward  to  Madras,  with  fpeci- 
mens  of  the  ftrata  at  different  depths.  The  ftone  is  beyond  all  comparifon  heavier  than  the 
fubftance  which  encrufts  It. 

"  It  appears  extraordinary  how  this  ftone,  fo  concealed,  fhould,  under  fuch  difficulties,  have 
been  fought  for,  and  applied  to  any  purpofe  j  and  that  the  knowledge  of  the  few  people 
who  dig  for  it,  and  who  do  fo  from  father  to  fon,  is  confined  entirely  to  the  finding  the  ftone. 
For  they  told  me  they  knew  none  of  its  ufes,  and  that  the  labour  was.fo  hard,, and  their 
gain  fo  fmall,  that  they  would,  through  choice,  rather  work  in  the  fields ;  that  the  fale  of  it, 
from  the  fpot,  is  confined  folely  to  the  glafs-fellers,  who  vend  it  ever  the  whole  country, 
and  who  had,  while  I  was  there,  above  forty  Parriar  horfes,  bullocks,  &c.  ready  in  the 

3  0^2  Pollam 


480  Oil  the  Cirundum  ^trnte  froin  Afin. 

PoUam  to  carry  it  to  Tinncvelly,  and  tlie  fouthern  countries  •,  through  which  trgek,  if  tlic 
ftone  is  known  in  Europe,  I  apprehend  it  has  found  its  way  by  means  of  the  Dutch. 

"  The  people  on  the  fpot  declare  it  is  to  be  got  in  no  other  fituation,  or  place,  whatever  j 
and  the  ftone-cutters  tell  me,  they  can  do  nothing  without  it.  It  pays  no  duty  either  where 
dug  up  or  retailed. 

*'  The  colour  of  the  ftone  is  cither  very  light  brown,  or  purplifh,  in  the  proportion  of 
twenty  to  one  of  the  latter ;  but  in  ufe  no  preference  is  given,  and  they  are  ufed  equally. 
To  an  indifferent  perfon  the  moft  ftriking  circumftance  is  its  great  weight. 

*•  As  the  fpot  I  have  been  fpcaking  of  now  compofes  a  part  of  the  Cwnpany's  territories, 
the  moft  minute  information  on  the  fubjeiS  may  be  acquired. 

"  I  felt  particular  fatisfaftion  at  having  been  the  firft  European  who  was  ever  at  the  place  ; 
and  I  fhall  be  much  gratified,  if  the  account  given  meets  with  your  approbation. 

^  I  fliall  difpatch  a  load  of  the  ftone  in  a  day  or  two,  which  I  got  at  the  PoUam,  with 
the  charge  of  it.    The  diftance  from  this  place,  by  Namcul,  is  84  miles. 

*'  The  charge:  of  50/J.  weight  (f  Corundum. 
"  Nine  Tritchinopoly  meafures  of  the  corundum  ftone  weigh  501b. 

**  Average  and  Coft  at  the  Pits  *. 
♦'if  Madras  farams  per  raeafure  _        _        -        -        . 

Cooley,  from  thence  to  Tritchinopoly  -        - 

Ditto  from  Tritchinopoly    -        -        •        -        - 

Pagodas  2 

«  The  ftone  is  deliTcrcd  by  meafures,  and  paid  for  at  the  PoUam  in  the  gold  fanam. 

"  I  am,  &c. 
«Nov.  15, 1792.  "  EDWARD  GARROW.'* 

This  letter  contains  very  interefting' topographical  obfervations  on  the  mine.  The  fpecimens 
fent  were  of  one  fort  of  a  greyifli  colour,  wth  a  fhade  of  green.  The  entire  cryftals  which  I 
fek£ied  among  the  broken  ones  were,  of  courfe,  few  in  proportion ;  but  with  the  addition  of 
fome  diftba  cryftals,  which  Col.  Cathcart,  and  Capt.  Colin  Macauley  had  fent  me,  have  been 
fufBcient  to  afcertain  the  ftrufture  and  form  of  the  cryftals,  of  which  an  analytical  defcription 
will  clofe  this  paper.  I  fhall,  therefore,  now  fay  nothing  concerning  their  form,  but  pro- 
ceed to  give  an  account  of  the  varieties  of  corundum  ftone,  which  I  have  obtained  from 

India  and  China. 

In  the  year  1786,  Col.  Cathcart  fent  mea  fmall  fragment  of  a  ftratified  mafs  from  Bengal, 
Vrith  this  label :  "  Corundum,  much  inferior  in  price  to  that  of  the  coaft."  It  is  of  a  purplifti 
hue  i  its  frafture  like  compaft  fand-ftones }  and  a  confufed  cryftallization  appears  in  all 

•  The  abo*«  h  the  prime  coft.    I  have  been  informed  by  correfpondenW  who  purchafed  fome  in  retail, 

tktt  it  was  fold  for  about  fix  MUngs  a  pound  at  Madras. 

parts 


P. 

F. 

c. 

0 

13 

40 

0 

28 

40 

I 

n 

40 

!  2 

10 

40 

Oh  the  Coi'iitidum  Staiie  fi-tvt  Afia.  481 

parts  of  the  ftone,  by  fibres  of  a  white  colour,  from  which  the  light  Is  refle£led  as  In  feld- 
fpar,  &c. 

i  have  fince  obtained  a  larger  lump  of  the  ftone  of  the  fame  texture,  but  rather  paler  in  its 
purplifh  hue.  Sir  John  Macgregor  Murray  informed  me,  that  it  is  called  by  the  natives  of 
Bengal,  coronet  and  ufed  for  poliftiing  ftones,  and  for  all  the  purpofes  of  emery. 

Its  fpecific  gravity  is  3,876. 

Capt.  Colin  Macauley  procured  a  lump  of  corundum  from  lifikuldar  (a  poliflier,  this  term 
Is  mod  appropriate  to  polilhers  of  fteel),  in  whofe  family  it  had  been  above  twenty  years,  em- 
ployed for  grinding  and  polilhing  ftones  or  gems.  The  ufe  to  which  it  had  been  fo  long  de- 
voted, had  occafioned  grooves  in  its  furfaces  which  facilitated  greatly  the  examination  of  its 
ftrufture.  It  is  about  5^  inches  long,  3^  inches  broad,  and  above  two  inches  thick.  On 
one  of  its  broad  furfaces  are  two  oval  grooves ;  one  of  them  is  four  inches  long,  one 
broad,  and  ^  of  an  Inch  deep.  On  the  oppofite  fide  Is  a  fliorter  oval  groove,  above  2i:  ifiches 
long,  I  k  inch  broad,  and  one  inch  deep.  In  thefe  grooves,  the  ends  of  the  laminae  of  the  clafs 
refleft  the  light  like  the  cryftals.  It  ferves  as  a  fpecimen  of  the  fimple  apparatus  of  an  In- 
dian lapidary.  Stones  polilhed  in  thefe  grooves,  would  be  of  the  common  India  polilh,  and 
form  en  cahochony  which  Is  often  called  tallow-drop  from  the  French  lapidaries'  term  goutte 
tje  fuif,  convex,  oval,  or  circular.  A  very  fmall  quantity  of  the  corundum  powder  would 
be  required,  as  the  aftion  of  the  powdered  corundum  and  gems  on  the  lump  of  corun- 
dum would,  as  appears  from  the  depth  of  the  grooves,  wear  away  from  It  a  fupply  of 
powder  for  the  operation  of  polifhing.  It  appears  to  be  part  of  a  larger  mafs.  Is  of  a 
purplilh  colour,  and  of  the  fame  laminated  texture  as  the  cryftals  of  corundum;  It  has 
this  peculiarity,  there  appear  cracks  branching  Irregularly  acrofs  the  lamlnse  of  the  lump^ 
which  are  filled  with  homogeneous  matter,  diftinguiflied,  however,  by  the  fuperior  pu- 
rity, which  might  be  expected  to  arife  from  the  degree  of  filtration  required  for  Its  de- 
pofition  In  the  fiflures.  Some  of  thefe  cracks,  which  terminate  on  the  furface,  appear 
to  have  the  fame  cryftallized  arrangement  which  charafterizes  the  laminse  of  corundum. 
The  cracks  not  being,  in  any  degree,  influenced  in  their  diredlion  by  the  laminse  of  the  cryftal- 
lized mafs,  it  is  probable  they  had  not  been  confolidated  when  they  cracked ;  and  from  this 
fpecimen,  we  may  expe£t  to  find  corundum  cementing  mafles  of  ftone  by  the  fame  procefs  of 
ftalaftitical  cementation,  by  which  quartz  and  calcedony  conneft  great  nodules  and  mafles  of 
fdiceous  ftones. 

In  this  fpecimen,  I  confider  the  veins  as  pure  corundum,  that  Is,  having  the  fame  fpecific 
gravity,  hardnefs,  and  texture,  as  corundum  cryftals ;  and  I  found  the  whole  lump  poflefled 
all  the  qualities  of  corundum,  except  its  fpecific  gravity,  which  amounted  only  to  2,785  ;  " 
and,  in  this  property,  it  correfponded  nearly  with  the  jnatrix  of  the  corundum  cryftals,  or 
the  vein  in  which  corundum  is  before  ftated  to  be  found ;  the  fpecific  gravity  of  which  Is 
2,768.  The  texture  of  the  matrix  appears  fometimes  like  adularia,  and  confufedly  cryftal- 
lized i  often  compa£l  like  cipoline  or  primitive  marble ;  fometimes  fparry,  fometimes  granu- 
lated j  and  on  the  outfide  of  the  vein,  and  near  fiflures,  decompofed  and  becoming  opaque. 
la  all  its  ftates  it  fcratches  glafs,  but  not  rock-cry ftal,  polfibly  from  want  of  adherence  of  Its 

particles : 


"  4Ba  On  the  Corundum  Stone  from  Afta. 

particles:  and  in  this,  it  differs  from  the  fubftance  of  the  above  lump,  which  cuts  glafs  and 
rock-cryftal  with  great  facility. 

This  lump,  and  the  matrix  of  corundum,  appeared  to  poflefs  the  fame  properties  as  corim- 
dum,  when  examined  by  the  blow-pipe  with  the  different  fluxes.  i 

The  matrix  of  corundum  having  fometimes  an  appearance  like  adularia  and  feldfpar,  I  af-- 
certained,  by  Mr.  Hatchett's  fcales,  the  fpecific  gravity  of  adularia  to  be  ^,558,  and  of  feld- 
fpar 2,555.  T^^  corundum,  and  the  lighter  corundum  of  the  lumpj  cut  adularia  and  feld- 
fpar; the  latter  effervefced,  and  combined  with  foda,  whicTi  the  former  did  not. 

It  is,  therefore,  evident  that  the  matrix  of  corundum,  or  fubfliance  of  the  vein,  is  a  difl;in£t 
fubftance  from  adularia  and  feldfpar,  and  nearly  connefted  with  corundum. 

The  matrix,  or  vein,  contains  atfo  a  black  fubftance  like  thorl,  which,  On  clofer  examination, 
appears  to  be  hornblende.  This  fubftance,  Mr.  Garrowliad  remarked  to  have  the  appearance' 
of  charcoal ;  and,  on  that  account,  he  had  attributed  the  formation  of  thefe  ftrata  to  the  agency 
of  fire.  Other  gentlemen,  from  the  appearance  of  the  matrix  of  corundum,  have  ftated  it 
to  be  a  calcareous  vein. 

Mr.  Garrow  obferved  that  there  ran  through  the  ftrata,  in  which  the  corundum  was  found, 
veins  of  a  fubftance  like  dried,  pitch,  apparently  on  their  edge,  which  feparated  like  a  pack 
of  cards.  It  is  a  brown  micaceous  fubftance,  which,  in  drying,  foliates,  and  fliews  a  certain- 
degree  of  regular  arrangement  of  the  component  parts ;  in  this  cafe,  the  fragments  of  the  folia 
fubdivide  with  fome  degree  of  regularity  into  rhombs,  whofe  angles  are  60°  and  120°:  it  is 
more  fmooth  and  lefs  flexible  than  pure  mica. 

Thefe  are  all  the  forts  of  corundum  which  I  procured  from  India. 

I  now  proceed  to  the  refult  of  my  inquiries  in  China. 

I  requefted  Capt.  Gumming,  in  1786,  at  that  time  commanding  t"he  company's  fliip,  Bri- 
tannia, to  take  a  fpecimen  of  corundum  to  China,  to  afcertain  its  nature,  and  to  obtain  fpeci- 
mens,  if  poflible,  adhering  to  their  matrix,  and  regularly  cryftallized.  On  his  arrival  at  Can- 
ton, he  collecSled  the  information  I  wifhed,  with  the  good  fenfe  and  zealous  defire  which  he 
always  exerts  for  his  friends.  He  afcertained  that  the  ftone  I  inquired  for  was  in  common 
ufe  with  the  ftone-cutters ;  and  he  brought  me  the  ftone  in  its  rude  and  in  its  pounded  ftate, 
taking  care  to  feleft  the  moft  regularly  cryftallized  pieces,  and  others  adhering  to  the  rock. 
A  ftone-cutter  was  fawing  rock-cryftal  with  a  hand-faw,  which  he  alfo  brought  to  me ;  it 
is  a  piece  of  bamboo  flit,  about  three  feet  long,  and  i|  inch  broad,  thickened  at  the  handle 
by  a  piece  of  wood,  rivetted  with  two  iron  pins ;  having  a  lump  of  lead  tied  with  a  thong 
of  fplit  rattan,  fteadying  an  iron  pin,  on  which  the  end  of  a  twifted  iron-wire  is  fattened, 
which  'being  ftretched  to  the  handle,  is  pafled  through  a  hole  in  the  bamboo  with  the  fupcr- 
abundant  wire;  a  wooden  peg  being  preffed  into  the  hole,  keeps  the  bow  bent,  and  the  wire 
ftretched,  and  ferves  to  coil  the  fuperfluous  wire,  till,  by  fawing  the  cryftal,  the  ftretched 
wire  is  worn,  and  requires  to  be  renewed  from  the  coil.  The  twifted  wire  anfwers  the  pur- 
pofe  of  a  faw,  and  retains  the  powder  of  corundum  and  water,  which  are  ufed  in  this  opera- 
tion.    Dr.  Lind  had  before  brought  fpecimens  fimilar  to  the  above  from  China. 

From  Sir  Jofeph  Banks,  I  obtained  Dr.  Lind's  fpecimens,   and  fome  in  powder,  which 
Mr.  Duncan,  fupercargo,  in  China,  had  fent  him  with  the  Chinefe  name,  pou-fa.    The  ma- 
trix 


On  the  Corundum  Stone  from  Afia.  ^Jj 

frix  being  mixed  with  a  red  and  white  fparry  fubftance  and  mica,  is  generally  called  red 
granite;  but  it  appears  to  me  of  the  fame  nature  as  the  matrix  of  corundum  from  India. 
The  white  is  more  fibrous,  and.  like  cyanite;  the  red  part  of  it  is  compa£l  and  opaque; 
Other  parts  appear  to  foliate,  and  pure  mica  is  in  confiderable  patches,  and  generally  adheres 
to  the  cryftala.  This  corundum  is  of  a  darker  brown,  and  more  irregular  on  the  furface^ 
than  the  corundum  of  the  coaft,  and  often  mixed  with  black  iron  ore*  attraiiable  by  tlie 
magnet. 

It  is  defcribed  asthe  third  modification  of  the  corundum  cryftal  in  the  analytical  defcrip- 
tiori  which  follows.  The  chatoyant,  or  play  of  light,  on  thefe  dark  cryftals,  is  very  remark- 
able :  fome  are  of  a  bright  copper  colour;  others  exhibit  the  accident  of  refle£tion  of  light, 
which,  in' a  polifhed  ftate,  gives  varieties  to  the  cat's-eye,  ftar-ftone,  fun-ftone,  &c;  which  as 
yet  are  clafled  from  fuch  accident  without  ftridl  attention  to  their  nature,  which  is  various, 
and,  in  general,  has  not  been  afcertained., 

Thefe  are  the  circumftances  connefted  witlrthe  ftrata,  worth  mentioning^  The  examina- 
tion of  corundum,  on  which  our  prefent  knowledge  rells,  is  nearly  that  which  an  India  mi- 
neralogift  might  derive  of  the  hiftory  of  feldfpar  from  a  lump  of  Aberdeen  granite  out  of 
fine  or  two  different  quarries.  He  might  afcertaia  a  few  modifications  ^f  the  cryftal  of  feld- 
fpar, its  frafture,  and  matrix ;  but  he  would  have  no  knowledge  of  the  pureft  or  more  beau- 
tiful forts,  which  other  quarries  produce  in  Scotland,  at  Bavcrno,  at  St.  Gotliard,  and  Au- 
vergne.  I  therefore  think  it  effential  to  mention  that  corundum,  under  circumftances  fa- 
vourable to  its  cryftallization,  becomes  glafly  in  its  frafture,  and  of  various  colours.  I  have 
not  only  obferved  in  cryftals  of  corundum  fpecks  of  a  fine  ruby  colour,  but  I  have  fragments 
of  cryftals  in  texture  and  every  refpe£t  like  the  colourlefs  corundum,  of  a  fine  red  colour. 
it  is  certain  that  we  obtain  from  India,  corundum  which  may  pafs  for  rubies.  I  have  fent 
to  India  fome  of  the  corundum  with  fmall  ruby  fpecks,  which  were  not  fufficiently  diftin£l 
or  large,  either  for  meafurement  or  analyfis,  in  hopes  of  being  enabled  to  afcertaiu  correiHy 
the  form  of  Balam  rubies  found  in  corundum ;  in  'the  mean  time,  I  have  the  corundum  of 
a  fine  red  colour.  Looking  over  fome  poliflied  rubies  from  India,  I  feleiSled  one  which  ap- 
peared laminated  like  corundum,  and  had  ajfb  the  chfitoyant,  or  play  of  light,  ,on  its  laminae, 
which  formed  an  angle  in  the  ftone.  The  lapidary  called  it  an  oriental  ruby.  I  altered  the 
form  of  the  cutting  fo  fortunately  that  the  reflefted  rays  formed  a  perfe£i:  ftar;  a  phjenomenoa 
I  had  obferved  in  the  fapphire,  and  expelled  in  corundum,  but  not  in  the  oftoedral  ruby. 
The  fpecific  gravity  of  tliis  ftone  being  4,  j  66,  confirmed  my  opinion- that  it  is  one  of  the 
Salai7i  rubies,  fo  much  efteemed  by  tlie  natives  on  the  coaft  or  peninfula  of  India,  which  are 
found  in  the  corundum  vein.  The_fpecific  gravitj^  of  a  colourlefs  fapphire  very  fittle  lefs 
opaque  than  corundum,  forming  a'fo.a  perfe<3  ftar,  yas  4^000 ;  that  of  a  deep,  blue  fapphire,  . 
and  of  a  ftar-ftone,  4,035  ;  all  which  J  conneft  with  the  corundum ;  the  fpecific  gravity  of  a 

.  ,  ■  ■•  « 

*  A  fmall  group,  confifting  of  three  or  four  cftoedral  cryftals,  prefents  the  lead  common  variety  of  thi»  • 

kind  of  iron  ore  ;  the  edges  of  the  oftoedra  being  replaced  by  planes,  which  altnoft  cover  the  triangular  planes, 

Rome  de  i'ljk.    Criftallcg.  vol.  IV.  plate  4,  fig.  6g, 

diftina 


484  0«  the  Corundum  SUfte/rotn  AJia, 

diftinft  cryftal  of  which  was  3,950 ;  of  a  fragment  of  ruby-coloured  corundum,  3,959 ;  and 
of  a  fragment  of  corundum  with  vitreous  luftre,  33954. 

It  may  be  objefted  to  me,  that  Bergman  has  ftated  the  variety  of  fpecific  gravity  in  gem« 
to  be  fo  great,  as  to  leave  no  certain  rule  of  judging  thereby  of  the  fpecies.  He  obferved, 
that  the  topaz  generally  prevails  in  weight,  being  from  3,460  to  4,560 ;  0ie  ruby  from  3,180 
to  4,240  ;  then  the  fapphire  from  3,650  to  3,940*.  But,  in  the  preceding  page,  he  had 
faid,  "  Analyfi  cryftallorum  tarn  ejufdem  quam  diverfx  figurse  multum  lucis  fcientia  cx- 
peftat.  nise  quarum  antea  compoGtionem  explorare  licuit  naturali  forma  per  artem  privatae 
erant."  It  is  not,  therefore,  an  hypothefis  unworthy  of  examination  wliich  I  advance,  that 
gems,  derived  from  the  reftangled  oftoedra,  whofe  fpecific  gravity  is  above  3,300  to  3,800, 
will  be  found  to  be  diamonds,  or  oiSloedral  rubies ;  and  thefe  will  be  eafily  diftinguilhed 
from  each  other  by  their  luftre  and  .hardnefs.  Diamonds,  whether  red,  yellow,  blue,  or 
white,  being  hardeft,  though  their  fpecific  gravity  will  be  lefe  j  viz.  from  3,356  to  3,471, 
as  I  found  among  different  diamonds  in  my  collection :  whereas  the  oftoedral  ruby  was 
from  3,571  to  3,625,  and  inferior  in  hardnefs  not  only  to  the  diamoitd,  but  to  the  corun- 
dum ;  the  fpecific  gravity  of  which,  in  its  different  appearance  of  form  and  colour,  I  found 
to  vary  from  3,876  to  4,166  ;  and  I  fuppofe  it  to  be  fubjeft  to  a  variation  from  3,300  to 
4,300 :  after  which  the  jargon  will  come  with  a  fpecific  gravity  of  4,600 ;  eafily  diftin-  " 
guiihed  alfo  by  its  cryftallization  from  the  above-mentioned  gems.  The  above  fpecific  gra- 
vities Mr.  Hatcliett  very  obligingly  aflifted  me  in  taking  with  his  accurate  fcales,  in  the  tem- 
perature of  60°.  It  will  not  be  underftood  that  I  depend  entirely  on  the  fpecific  gravity  \ 
on  the  contrary,  I  connedt  this  quality  with  cryftallization  :  hardnefs  is  the  next  criterion  \ 
and  analyfis  muft  feparate  the  component  parts,  and  demonftrate  the  analogy,  or  identity, 
of  fubftances,  or  of  compounds.  The  improvements  of  Mr.  Klaproth's  procefs  are  evi- 
dent by  the  comparifon  of  his  firft  analyfis,  and  in  his  laft  analyfis  of  corundum. 
In  the  firft  it  confifted  of 

Corundum  earth  -  -  «  -  6%    o 

Siliceous  earth        --  »  •  «  3^5° 

Iron  and  nickel      -        »  u  ^         »  o  50 


By  the  laft  analyfis  of  Mr.  Klaproth,  the  corundum  of  the  peninfula  of  India  con- 
fifted of 

Argillaceous  earth  ,  -  -  » 

Siliceous  earth  «        -  _ 

Oxide  of  iron  _        .  .  -  - 

Lofs  -  -        »  »  •  • 


100 

;ninfula 
89  5a 

5  50 

I  25 

3  75 

JOG 

»  De  Terra  Gemmaium.  Berg.  Opufc.  vol.  II.  p.  104. 


The 


Corundum  Stone  from  Afia,— -Singular  Lunar  Halo.  485 

The  corundum  of  China, 

Argillaceous  earth  -  »  «            » 

Siliceous  earth  .    -  •  - 

Oxide  of  iron        ■  .  -  - 

.                   Lofs          -           -  •>  >  ^           . 


That  the  analyfis  of  fapphire  of  Mr.  Klaproth  may  be  compared,  it  is  here  added. 
Argillaceous  earth  -  -  -  -  98  50 

Calx  of  iron  -  -  -  -  .  10 

Calcareous  earth  -  •  *  -  o  50 


84 

0 

6 

so 

7 

SO 

2 

0 

100 

100 

Iron-ore  cryftalllzed  is  often  mixed  with  the  Chincfe  corundum,  as  I  have  before  ftatcd, 
and  may  be  confidered  as  accidentally  interpofed,  not  combined.  In  the  corundum  of  the 
coaft,  the  greenifli  colour  may  indicate  the  combination  of  iron,  as  the  blue  colour  does  in 
the  fapphire  ;  and  the  proportion  of  iron  in  both  is  nearly  alike. 

There,  then,  is  the  ~ — ^-^  and   i-  of  filex  in  corundum,  evidently  an  integral 

100  100  '  * 

part  of  the  coarfe  corundum  cryftal,  and  not  of  the  fapphire ;  but  it  y/\\\  require  an  analyfis 

of  the  vitreous  or  pellucid  corundum  to  decide  that  filex  is  a  conftituent  part  of  corundum : 

there  will  then  remain  to  account  for  the  calcareous  earth  ;  and,  having  eftabliflied  its  being 

a  conftituent  part  of  the  fapphire,  the  fmall  proportion  of  ■ cannot  be  expefted  to 

produce  a  very  notable  difference. 

It  is  not  neceflary  to  do  more  than  thus  to  hint  at  what  further  analyfis  and  examination 
of  former  experiments  are  required,  to  afcertain  the  analogy  or  identity  of  the  fapphire  and 
oriental  ruby  with  corundum. 

I  have  before  ftated,  that  I  have  corundum  (which  has  the  fame  texture  and  frafture  as 
the  common  colourlefs  corundum)  of  a  ruby  red,  and  alfo  of  fapphire  blue,  and  of  fapphire 
blue  and  white  colours. 

I  have  fapphires  yellow  and  blue,  white  and  blue,  brown  and  greenifli,  and  of  a  purplifli 
hue  ;  thefe  I  fliould  confider  as  corundum,  with  fratSture  of  vitreous  luftre. 

(To  be  continued.) 

II. 

Jin  Account  of  aftngular  Halo  of  the  Moon.     In  a  Letter  from  WiLLIAM  Hall,  Efq.  of 
Whitehall,  F.R.S.  Edin.  to  Sir  James  Hall,  Bart.  F.R.S.  Edin.* 
DEAR  SIR  JAMES,  Whitehall,  near  Berwick,  April  2,  1796. 


I 


SEND,  under  cover,  tlie  reprefentation  of  a  very  fingular  halo  of  the  moon  (pi.  XXII. 
fig.  25.)  feen  here  on  the  night  of  the  i8th  of  February  laft,  about  ten  o'clock  ;  and  this  I 

*  Edinburgh  Tranfaa';ons,  vol.  IV.  page  173. 

Vol.  II. — Ffb.  i  799.  3  R  have 


Jfi6  Singular  Halo  of  the  Moon. 

have  hitherto  delayed,  in  order,  if  poffible,  to  gain  farther  information  in  the  neighbourhood 
concerning  it. 

During  the  fhort  continuance  of  the  fmall  halo,  which  did  not  exceed  ten  minutes  after 
I  got  notice  of  it,  I  Could  not  lay  my  hands  on  any  other  inftrument,  to  take  the  angles,  but. 
a  Siflbn's  theodolite,  which  imlucklily^  having  been  conftrudied  fo  as  not  to  admit  of  a  ver- 
tical angle  fo  great  as  the  moon's  altitude  then  was,  I  laid  it  afide,  not  recoUefting  that  it 
might  have  meafured  feveral  of  the  fmaller  angles.  But  I  obferved  fundry  marks,  from 
which  I  took  the  angles  as  exactly  as  I  could  next  day. 

The  moon  was  about  fouth-weft,  and  her  altitude  nearly  54°,  which,  of  confequence, 
was  alfo  the  higheft  altitude  of  the  limb  of  the  greater  halo  where  it  was  higheil,  and 
where  it  paffed  tlirough  the  moon  ;  the  altitude  of  its  oppofite  limb  was  14°  ;  fo  that  its 
diameter  fubtended  an  angle  of  no  lefs  than  a  hundred  and-twelve  degrees. 

The  diameter  of  the  fmall  halo,  which  appeared  to  be  a  perfefl;  circle,  with  the  moon  in  its- 
centre,  I  found,  after  repeated  trials,  was  under  12°,  and  more  than  8°  ;  but  as  the  different 
diameters  of  the  large  halo  were  not  meafured,  it  cannot  pofitively  be  affirmed,  that  it  was  an 
exa£l  circle ;  on  the  contrary,  its  limb  did  not  feem  to  interfeft  the  fmall  circle  quite  fo 
much  at  right  angles  as  the  circular  arch  delineated  in  the  plan.  It  may,,  therefore,  have 
been  fomewhat  elliptical. 

The  fmall  circle  was  remarkably  bright,  particularly  at  "Weft  Refton,  about  five  miles  to 
the  northward,  the  only  other  place  where  the  halo  was  obferved,  and  where  it  was  thought 
to  fend  forth  flame.  The  fmall  halo  alfo  continued  there  much  longer  than  here,  where  fome 
thin  fleecy  clouds  foon  put  an  end  to  it ;  but  the  large  halo  continued  with  us  near  an  hour. 

The  weather  about  this  time  was,  for  the  feafon,  remarkably  mild,  particularly  on  the 
day  of  the  halo.  The  fky  was  pretty  clear  all  that  day,  and- alfo  in  the  evening ;  but,  at 
the  time  of  the  halo,  there  was  a  fmall  degree  of  hazinefs,  particularly  towards  the  north, 
which  did  not,  however,  prevent  the  moon  from  fhining  with  brightnefs  ;  and  the  ftars 
were  even  vifible  within  the  circle  of  the  fmall  halo  :  there  was  little  or  no  wind. 

The  circles,  or  belts,  of  both  halos  are  reprefented  in  the  plan  nearly  of  their  apparent 
fcreadth,  or,  perhaps,  a  little  broader :  the  light  of  both  was  whitifh,  and  confiderably 
bright,  without  colour ;  that  of  the  large  circle  was  the  paler  of  the  two,  particularly 
where  it  paffed  through  the  fmall  circle :  to  the  northward  it  was  fomewhat  obfcure. 

By  means  of  tlie  angles  taken  as  above,  after  having  afcertained,  on  a  vertical  circle  of  the 
heavens,  the  fituations  of  the  moon,  of  the  fmall  halo,  and  of  the  north-eaflern  Kmb  of  the 
large  halo,  whofe  fouth-weflern  limb  pafTed  through  the  moon,  the  whole  was  projefted  on 
the  horizontal  plane,  as  in.  the  figure  already  referred  to.  The  moon,  a  little  more  than 
half,  is  placed  in  the  centre  of  the  fmaller  halo ;  and  both  halos  are  reprefented  in  their 
true  fituations,  relatively  to  the  horizon,  and  in  the  circular  fliape  which  they  appeared  to 
have  ;  though  they  ought,  perhaps,  to  have  been  fomewhat  forefliortened,  and  thrown  into 
an  elliptic  form. 

This  halo,  as  you  wdll  fee  by  the  above  defcription,  appears  to  be  of  the  kind  called  by  the 
learned  a  corona ;  and  as  it  fomewhat  refembles  the  famous  one  of  the  fun  obferved  at 

Rome 


Great  Retardation  of  tliiids  through  irregular  Pipes.  487 

Rome  in  the  year  1629,  and  defcribed  by  Scheiner*,  it  deferves  the  more  attention,  efpe- 
cially  as  the  great  halo  on  the  prefent  occafion,  having  its  fouth-weftern  limb  elevated  to  the 
height  of  540°,  and  its  nortli-eaftern  deprefled  to  within  14°  of  the  horizon,  was  in  an  ob- 
fique  pofition,  not  eafily  reconciled  with  the  theory  of  Huygens,  which  Iccms  to  require  that 
fuch  circles  fhould  be  equally  elevated  above  the  horizon  all  round.  It  aifo  (hews  tliat 
Scheiner's  original  plan  of  the  halo  at  Rome,  which  reprefented  it  as  oblique,  may  have 
been  right,  and  that  Huygens'  corre£lion,  whicli'make3  it  parallel  to  the  horizon,  was  pro- 
hably  an  erroneous  conjediure. 

lam, 

dear  Sir  James, 

your  humble  fervant, 

WILLIAM  HALL. 


in. 

Experimental  Refearches  concerning  the  Principle  of  the  lateral  Communication  of  Motion  in  Fluids^ 
applied  to  the  Explanation  of  various  Hydraulic  Phenomena.  By  Citizen  J.  B.  VeNTURI, 
Prof ejfor  of  Experimental  Philofophy  at  Modena,  Member  of  the  Italian  Society,  of  the  Inflitute  of 
Bologna^  the  Agrarian  Society  of  Turin,  (Sfc. 

(Continued  fronn  page  426,  vol.  II.) 

Experiment  XXIII.  Tlie  two  tubes  a  B  C,  D  E  F,  fig.  14.  Plate  XXn.  are  15  inches 
long ;  their  diameter  is  14,5  lines.  The  conical  portions  A,  D^  have  the  form  of  the  con- 
traftion  of  the  vein  of  fluid,  and  are  applied  to  the  orifice  P,  fig.  i .  Plate  VIII.  of  the  pre- 
fent volume,  which  is  18  lines  in  diameter,  with  32,5  inches  depth,  or  charge  of  fuperin- 
cumbent  fluid.  The  elbows,  or  flexures,  B  C,  E  F,  are  made  in  the  plane  of  the  horizon. 
Thefe  two  pipes  are  made  of  copper  foldered  with  filver,  and  the  workmanfhip  carefully 
executed.  The  curvature  B  C  was  drawn  out,  or  bended,  into  the  form  of  a  quarter  of  a  circle, 
by  filling  the  tube  with  melted  lead,  in  order  that  it  might  preferve  its  diameter  during  the 
ad):  of  bending.  The  elbow  D  E  F  is  conftruded  in  a  right  angle.  The  expenditure  through 
thefe  two  tubes' was  compared  with  that  afforded  through  a  right-lined  cylindrical  tube  of 
fimilar  dimenfions,  and  in  like  circumftances.  The  four  cubical  feet  of  water  flowed  out  of 
the  cylindrical  tube  in  45"  j  out  of  the  curved  tube  A  B  C  in  50" ;  and  out  of  the  angular  tube 
D  E  F  in  70". 

4.  It  is  of  importance  that  the  tube  B  C,  fig.  13.  Plate  VIII.  Ihould  be  of  an  equal 
diameter  throughout.  It  is  not  enough  that  care  be  taken  that  there  fliall  be  no  contrac- 
tion, it  is  alfo  neceflary  that  it  fliould  not  be  enlarged  at  any  part.  For  fuch  enlarge- 
ments have  nearly  the  (iime  bad  effed  in  the  expenditure  as  contraftions.  The  pipe  A  O, 
fig.  12.  affords  a  much  lefs  quantity  of  fluid  with  the  dilatations  D  E,  H  I,  than  if  it  were 
of  a  diameter  equal  to  that  at  B  throughout  its  whole  length.     The  following  experiment 

agrees  with  the  tlieory. 

•  Smith's  Optics,  vol.  I.  §  534. 

3  R  2  Experiment 


488  Great  RelardatioH  of  Fluids  through  irregular  Pipes, 

Experiment  XXIV.  The  circular  orHlce  A,  fig.  1 2.  has  the  form  of  the  contradllon  of 
the  vein,  and  the  remaining  part  of  the  tube  is  interrupted  by  various  enlargements  of  its 
diameter.  This  tube  is  applied  to  the  aperture  P,  fig.  i .  The  dimenfions  of  its  parts 
meafured  in  Hnes  are  as  follows.  Diameter  at  A  =  1 1,2.  Diameter  at  B,  C,  F,  G,  &c.  =r  9. 
Length  of  B  C  =  F  G,  &c.  =  20.  Lengtli  of  C  D  =  E  F  =  G  H,  &c.  =  13.  Diameter 
of  the  enlarged  parts  =  24.  The  length  of  each  of  the  enlarged  parts  was  variable.  The 
firft  time  of  trial  it  was  38  lines,  the  fecond  76,  and  therefult  of  the  experiment  was  the 
fame  in  both  cafes.  ' 

Number  of  enlarged  parts.  Time  during  which  four  cubical  feet  Iflued  out, 

o  109" 

I  •      147" 

3  ^92" 

5  240" 

I  afterwards  applied  to  the  fame  orifice  a  tube,  having  the  fame  form,  and  the  fame  diameter, 
as  ABC,  but  cylindrical  throughout,  without  any  enlargements,  and  its  length  was  36  inches, 
the  fame  as  that  of  the  tube  with  five  enlarged  parts  ;  in  this  cafe  the  expenditure  of  four 
cubical  feet  was  made  in  148". 

When  the  fluid  pafles  from  C  to  the  middle  of  the  enlarged  part  D  E,  part  of  the  motion 
is  diverted  from  the  direftion  C  F  towards  the  lateral  parts  of  the  enlargement.  This  part 
of  the  motion  is  confumed  in  eddies,  or  againft  the  fides.  Confequently  there  remains  fo 
much  the  lefs  motion  in  the  following  branch  F  G.  This  is  alfo  the  caufe  which  deftroys, 
or  weakens,  the  pulfe  in  the  arteries  beyond  an  aneurifm. 

From  this  confideration  we  are  juftified  in  concluding,  that  if  the  internal  roughnefs  of 
a  pipe  diminifhes  the  expenditure,  the  fridlion  of  the  water  againft  thefc  afperities  does  not 
form  any  confiderable  part  of  the  caufe.  A  right-lined  tube  may  have  its  internal  furface 
highly  poliihed.  Throughout  its  whole  length,  it  may  every  where  poflefs  a  diameter  greater 
than  the  orifice  to  which  it  is  applied ;  but,  neverthclefs,  the  expenditure  will  be  greatly  re- 
tarded if  the  pipe  fhould  have  enlarged  parts,  or  fwellings.  This  is  a  very  interefting  cir- 
cumftance,  to  which,  perhaps,  fufficient  attention  has  not  been  paid  in  the  conftruftion  of 
hydraulic  machines.  It  is  not  enough  that  elbows  and  contractions  are  avoided ;  for  it  may 
happen,  by  an  intermediate  enlargement,  that  the  whole  advantage  may  be  loft,  which  may 
have  been  procured  by  the  ingenious  difpofitions  of  the  other  parts  of  the  machine. 

PROPOSITION  VIII. 

In  the  machine  for  blowing  by  means  of  a  fall  of  water ,  the  air  is  afforded  to  the  furnace  by  thr 
accelerating  force  of  gravity  and  the  lateral  communication  of  motion,  combined  together. 

The  Academy  of  Touloufe,  in  the  year  1791,  invited  philofophers  to  determine  the  caufe 
and  the  nature  of  the  ftream  of  air  which  is  produced  by  the  fall  of  water  in  certain  forges. 
I  propofe,  in  this  place,  to  develope  the  complete  aftion  of  this  kind  of  blowing  apparatus, 
and  to  afccrtain  the  beft  form  of  conftruiStion.     Kircher  is  the  firft  I  know  of  who  has  ex- 

plamed 


Explanation  of  the  EffeB  of  the  Water  blowing  Machine.  489 

plained  the  produdlon  of  wind  by  a  fall  of  water  *.  Barthes,  tKe  father,  has  given  a 
theory  which  appears  to  me  to  be  defe£tive  in  many  refpccSls  f .  Dietrich  was  of  opinion, 
that  this  wind  is  produced  by  the  decompofition  of  water  J.  Fabri  had  a  fimilar  notion  in 
the  lad  century  §.     Moft  philofophers  are  well  acquainted  with  this  kind  of  engine  H. 

I  fliall  begin  with  an  idea,  tlie  foundation  of  which  did  not  efcape  t^he  penetration  of 
Leonardo  Da  Vinci.  Suppofe  a  number  of  equal  balls  to  move  in  contact  with  each  other 
along  the  horizontal  line  A  B,  fig.  16.  Plate  XXII.  Imagine  them  to  pafs  with  an  uni- 
form motion,  at  the  rate  of  four  balls  in  a  fecond.  Let  us  take  B  F,  equal  to  1 6  feet 
Englifli.  During  each  fecond  four  balls  will  fall  from  B  to  F,  and  their  refpe£l:ive  diftances 
in  falling  will  be  nearly  BC=i,CD  =  3,  DE  =  5,  EF  =  7.  We  have  here  a  very 
evident  reprefentation  of  the  feparation,  and  fucceffive  elongation,  which  tlie  accelerating 
force  of  gravity  produces  between  bodies  which  fall  after  each  other. 

The  rain  water  flows  out  of  gutters  by  a  continued  current  5  but  during  its  fall  it  fepa- 
rates  into  portions  in  the  vertical  direction,  and  ftrikes  the  pavement  with  di(lin£t  blows. 
The  water  likewife  divides,  and  is  fcattered  in  the  horizontal  direftion.  The  ftream 
which  iffues  out  of  the  gutter  may  be  one  inch  in  diameter,  and  ftrike  the  pave- 
ment over  the  fpace  of  one  foot.  The  air  which  exifts  between  the  vertical  and  hori- 
zontal feparations  of  the  water  which  falls,  is  impelled  and  carried  downwards.  Other  air 
fucceeds  laterally ;  and  in  this  manner  a  current  of  air,  or  wind,  is  produced  round  the  place 
ftruck  by  the  water.  I  went  to  the  foot  of  the  cafcadcs  which  fall  from  the  Glaciere  of 
La  Roche  Melon,  on  the  naked  rock  at  La  Novalefe,  towards  Mount  Cenis,  and  found  the 
force  of  the  wind  to  be  fuch  as  could  fcarcely  be  withflood.  If  the  cafcade  falls  into  a 
bafon  the  air  is  carried  to  the  bottom,  whence  it  rlfes  with  violence,  and  difperfes  the  water 
all  round  in  the  form  of  a  mift. 

The  water  which  is  precipitated  in  the  hollow  internal  parts  of  mountains  carries  the  air 
with  it,  which  afterwards  iffuing  forth  from  apertures  at  the  foot  of  the  mountain,  pro- 
duces thofe  natural  blafts,  thofe  ventaroli  %  which  are  moft  frequently  obferved  in  the  vol- 
canic mountains,  bccaufe  thefe  mountains  are  moft  commonly  hollow  within. 

Let  B  C  D  E,  fig.  16.  reprefent  a  pipe,  through  which  the  water  of  a  canal  A  B  falls  into 
the  lower  receiver,  M  N.  The  fides  of  the  tube  have  openings  all  round,  through  which 
the  air  freely  enters  to  fupply  what  the  water  carries  down  in  its  fall.  This  mixture  of  wa- 
ter and  air  proceeds  to  ftrike  a  mafs  of  ftone  Q^  whence  rebounding  through  the  whole 
width  of  the  receiver  M  N,  the  water  feparates  from  the  air,  and  falls  to  the  bottom  at  X  Z, 
whence  it  is  difcharged  into  the  lower  channel  or  drain,  by  one  or  more  openings,  T,  V.  The 

*  Mundus  Subterr.  lib.  XIV.  Cop.'j,  edit.  i66z. 

"l-  Memoires  des  Savans  etrangers,  vo).  III.  p.  378. 

%  Git-s  de  Mineral  des  Pvrenees,  p.  48,  49. 

§  Phyfic.  traft  I.  lib.  II.  prop.  243. 

I  Aw  des  Forges,  part  II.     Mariotte  des  Eaux,  part  I.  difc.  III.  Tranfaft.  No.  473,  &c. 

^  Thefe  veniaroli  arc  fometimes  produced  by  the  difference  of  temperature  between  the  air  of  the  cavern 

•  and  the  external  air.     V.     Frors  the  effifls  they  fecm  to  be  oftener  proiluced  by  this  lad  caufc,  than  by  a 

fall  of  water.     On  this  fuhjedl  in  general,  ,n..meiy,  the   cold  winds  which  iffue  out   of  the   earth,  fee 

Philof.  Journal,  I.  219. — J^. 

air 


i}<jo  Theory  and  EJfeci  of  the  TVatei'-blowihg  Machiiw. 

air  being  lefs  heavy  than  the  water,  occupies  the  upper  part  of  the  receiver,  whence  being 
urged  through  the  upper  pipe  O,  it  is  conveyed  to  the  forge. 

Experiment  25.  I  formed  one  of  thefe  artificial  blowing  engines  of  a  fmall  fize.  Tlie 
pipe  B  D  was  two  inches  in  diameter,  and  four  feet  in  heiglit.  When  the  water  accurately 
filled  the  fediion  B  C,  and  all  the  lateral  openings  of  the  pipe  B  D  E  C  were  clofed,  the  pipe 
O  no  longer  offered  any  wind. 

It  is,  therefore,  evident  that  in  the  open  pipes  the  whole  of  the  wind  comes  from  the  atmo- 
fphere,  and  no  portion  is  afforded  by  the  decompofition  of  water.  Water  cannot  be  decompofed, 
and  transformed  into  gas,  by  the  fimple  agitation  and  mechanical  percuffion  of  its  parts.  The 
opinion  of  Fabri  and  Dietrich  have  no  foundation  in  nature,  and  are  contrary  to  experiment. 

It  remains,  therefore,  to  determine  the  circumftances  proper  to  drive  into  the  receiver, 
M  N,  the  greatefl  quantity  of  air,  and  to  meafure  that  quantity.  The  circumftances  which 
favour  the  moft  abundant  produdlion  of  wind,  are  the  following. 

It  is  known  that  in  the  parabola,  ii  d  xhe.  affumed  as  conftant,  d  y  will  decreafe  in  the 

ratio  of The  feparation  of  the  balls  in  fig.  15.  is  more  rapid  in  the  upper  fpaces  of 

V  X 

the  fall  than  in  the  lower.  In  order,  therefore,  to  obtain  the  greateft  effeft  from  the  acce- 
leration of  gravity,  it  is  neceffary  that  the  water  fhould  begin  to  fall  at  B  C,  fig.  16.  with  tlie 
leaft  poflible  velocity ;  and  that  the  height  of  the  water  F  B  Ihould  be  no  more  than  is  ne* 
ccffary  to  fill  the  fedion  B  C.  I  fuppofc  the  vertical  velocity  of  this  fediion  to  be  produced 
by  an  height  or  head  equal  to  B^  C. 

2.  We  do  not  yet  know,  by  direct  experiment,  the  diiiance  to  which  the  lateral  com- 
munication of  motion  between  water  aud  air  can  extend  itfelf ;  but  we  may  admit  with  con- 
fidence, that  it  can  take  place  in  a  fedion  double  that  of  the  original  fettion,  with  which 
the  water  enters  the  pipe.  l.et  us  fuppofe  the  fedion  of  tlie  pipe  B  D  E  C  to  be  double  the 
feflion  of  the  water  at  B  C ;  and  in  order  that  the  ftream  of  fluid  may  extend  and  divide 
itfelf  through  the  whole  double  fedlion  of  the  pipe,  fome  bars,  or  a  grate,  are  placed  in 
B  C,  to  diftribute  aud  fcatter  the  water  through  the  whole  internal  part  of  tlie  pipe. 

3.  Since  tlie  air  is  required  to  move  in  the  pipe  O  with  a  certain  velocity,  it  muft  be 
comprefl^ed  in  the  receiver.  This  compreffion  will  be  proportioned  to  the  fum  of  the  acce- 
lerations, which  fhall  have  been  dcflroyed  in  the  inferior  part  K  D  of  the  pipe.  Taking 
K  D=  1,5  feet,  we  Qiall  have  a  preffure  fufficient  to  give  the  requlfite  velocity  in  the  pipe 
O.  The  fides  of  the  portion  K  D^  as  well  as  thofe  of  the  receiver  M  N,  mull  be  exaiftly 
clofed  in  every  part. 

4.  The  lateral  openings  in  the  remaining  part  of  the  pipe  B  K,  may  be  fo  difpofed  and  mul- 
tiplied, particularly  at  the  upper  part,  that  the  air  may  have  free  accefs  within  the  tube.  I 
will  fuppofe  them  to  be  fuch  that  0,1  foot  height  of  water  might  be  fulEcient  to  give  the 
jieceflary  velocity  to  the  air  at  its  introduction  through  the  apertures. 

All  thefe  conditions  being  attended  to,  and  fuppofing  the  pipe  B  D  to  be  cylindrical,  it  is 
required  to  determine  the  quantity  of  air  which  pafles  in  a  given  time  through  the  circular 
fcaion  K  L.  Let  us  take  in  fett  K  6=1,5;  1^  C=B  F=a;  IB  D=^.  By  the  common 
theory  of  falling  bodies,  the  velocity  in  K  L  will  be  '],']6V{a  +  b — 1,4);  the  circular  fec- 
feoii  K  L  =  0,7  850'.     Admitting  that  tlic  air  in  K  L  to  have  acquired  the  fame  velocity  as 

the 


Blowing  Machine. — Drainage  •without  Engines  491 

the  water,  the  quantity  of  the  mixture  of  the  water  and  air  which  pafles  in  a  fecond 
through  K  L  is=6,  i  a^V  {a+b — 1,4).  We  niuft  deduft  from  the  quantity  {a+b — 1,4) 
that  height  which  anfwers  to  the  velocity  the  water  muft  lofe  by  that  portion  of  ve- 
locity which  it  communicates  to  the  air  laterally  introduced ;  but  this  quantity  is  fo  fmall 
that  it  may  be  neglefted  in  the  calculation.  The  water  which  pafles  in  the  fame  time  of 
one  fecond  through  B  C  is  =  0,4  a^  V  (a +  0,1).  Confequcntly,  the  quantity  of  air 
which  pafles  , in  one  fecond  through  K  L,  will  be=6,  i  a"- V  {a-\-l> — 1,4) — 0,4  a^V 
(a +0,1),  taking  the  air  itfelf,  even  in  its  ordinary  ftate  of  compreflion,  under  the  weight 
of  the  atmofphere.  It  will  be  proper,  in  praftical  applications,  to  dedudt  one-fourth  from 
this  quantity;  I,  on  account  of  the  Ihocks  which  the  fcattered  water  fuftains  againft  the  in-- 
ferior  part  of  the  tube,  which  deprive  it  of  part  of  its  motion ;  and,  2,  becaufe  it  muft  happen 
tliat  the  air  in  L  K  will  not,  in  all  its  parts,  have  acquired  the  fame  velocity  as  the  water. 

If  the  pipe  O'do  not  difcharge  the  whole  quantity  of  air  afltirded  by  tlie  fall,  tlie  water 
will  defcend  at  X  Z;  the  point  K  will  rife  in  the  pipe,  the  afflux  of  air  will' diminijh,  and 
part  of  the  wind  will  iflue  out  of  the  lower  lateral  apertures  of  the  pipe  B  K. 

r  (hall  not  here  examine  the  greater  or  lefs  degree  of  perfeftion  of  the  difi"erent  forms  of 
water-blowing  machines,  which  are  ufed  at  various  iron  forges,  fuch  as  thofe  of  the  Catalans, 
and  elfewhere.    Thefe  points  may.  be  eafily  determined  from  the  principles  here  laid  down; 

PROPOSITION  IX.. 

It  is  pojthle,  by  means  of  a  fall  of  ivater,  to  drain  a  piece  of  ground.,  nvithotft  the  help  of  machines ;  ■ 
even  though  the  ground fhould  lie  on  a  lower  level,  than  the  ejlabltfhed  current,  below  the  fall. 

The  means  of  doing  this  is  pointed  out  in  the  firft  experiment  of  this  treatife.  We  have 
feen  that  the  water  contained  in  the  veflel  D  E  F  B,  fig.  3.  Plate  VIII.  ifllies  through  the 
channel  M  B  V,  which  is  higher  than  the  furface  of  the  water  itfelf,  becaufe  the  fluid  which 
pafles  through  A  C  carries  with  it  the  water  contained  in  the  veifel. 

In  the  artificial  fall,  which  is  procured'  in  channels  to  give  motion  to  mills,  when  the 
water  ruflies  down  by  a  re£fcangular  trunk  of  wood,  D  B  C  F,  fig.  1 7,  placed  nearly  horizon- 
tal in  the  middle  of  the  lower  channel,  the  furface  of  the  water  at  K  is  one  or  two  feet 
Beneath  the  inferior  current  (or  back-water)  F  L*.  The  water  at  F  tends  to  return  and  defcend 
along  F  K ;  but  the  current,  by  its  lateral  adlion,  confliantly  carries  it  away,  and  does  not  permit 
it  to  Aide  down  to  K.  If  an  opening  G  be  made  in  the  lateral  fides  of  the  trunk,  the  waters  from 
lands  lower  than  the  current  of  the  inferior  ftream  F  L  may  be  drained  oS.  In  a  commiflion 
with  feveral'of  my  colleagues,  I  once  propofed,  that  tliis  principle  fliould  be  applied  to  a  cafe 
of  pradlice.     The  projcft  was  adopted,  and  the  drainage  fucceeded  very  welL 

The  reflangular  conduit  D  D  F  C  muft  be  prolonged  to  a  certain  extent  along  the  lower 
channel,  otherwife  the  water  might  flow  back  from  F  to  K,  and  oppofe  the  drainage  through  G. 
The  mill-wrights  are  aware  of  the  utility  of  this  prolongation.     Experiment  has   taught 

*  This  depreflion  of  the  level  has  already  been  noticed  in  K.  Guilielmi,  della  natura  de  fiumi,  cap.  7, 
fig.  46.  Boflut,  art.  7:1,  The  whe«l  alluded  to  in  the  text  muft,  I  preiumt,  be  of  that  kind  which  we 
call  a  breaft- wheel. — N. 

tlieni= 


jjpa  C^nfiderattons  refpeciing  Eddies  in  Water, 

them,  that  it  prevents  the  water  from  retumiflg  back  fo  readily  in  the  time  of  floods,  which 
might  check  the  motion  of  the  water-wheel.  For  this  purpofe,  they  make  the  upper  part  D  F 
at  the  height  of  the  waters,  which  the  mill-ftream  can  refift  or  fupport.  The  town  of  Final, 
in  the  territory  of  Modena,  having  charged  me  with  the  dire£lion  of  changing  the  courfe  of 
part  of  the  waters  of  the  Panaro,  which  the  circumftances  of  the  town  required  to  be  donej 
i  availed  myfelf  of  this  prolongation  of  the  tail-pipe  D  F,  combined  with  other  artifices,  to 
ifnaintain  the  aftion  of  mills  in  the  new  channel;  and  I  fucceeded  not  only  beyond  the  expec- 
tation of  the  inhabitants,  but  even  beyond  my  own  hopes. 

PROPOSITION  X. 

The  eddies  of  the  water  in  rivers  are  produced  by  motion,  communicated  from  the  more  rapid  parts 
of  thefiream  to  the  lateral  parts,  -which  are  more  at  reft. 

■  Few  authors  have  examined  the  caufc  and  the  efFe£l:s  of  the  eddies  of  water  in  rivers ;  and 
thofe  who  have  undertaken  this  inveftigation,  do  not  appear  to  have  been  very  happy  in  their 
refearches. 

The  water  which  moves  in  the  channel  M  N  H,  fig.  19.  meets  the  obftacle  B  A,  which 
impedes  its  courfe,  and  caufes  it  to  rife  and  difcharge  itfelf  in  the  diredlion  A  C  with  an  in- 
creafed  velocity.  Suppofe  the  water  in  B  D  C  A  to  be  dormant,  the  current  A  C  communis 
cates  its  motion  to  the  lateral  particles  E  (Prop.  I.),  and  conveys  them  forward ;  the  furface  of 
the  dormant  water  becomes  deprefled  at  E,  and  the  mod  remote  particles  towards  D  are  urged 
according  to  the  laws  of  the  equilibrium  of  fluids  to  fill  the  depreflion.  The  current  A  C 
continues  to  carry  them  off,  and  the  fpace  B  D  C  A  continues  to  be  exhaufted.  The  water 
.  of  the  current  A  C,  by  virtue  of  the  fame  laws,  is  a£led  upon  by  a  conftant  force  which  urges 
it  towards  the  cavity  E,  while  its  natural  courfe  or  projedlion  carries  it  towards  A  C.  Under 
the  agency  of  thefe  two  forces,  the  water  A  C  acquires  a  curve-lined  motion  in  C  D,  and  de- 
fcends  as  it  were  through  an  inclined  plane,  becoming  retrograde  in  D  E,  whence  it  would 
proceed  to  ftrike  the  obftacle  B  A,  and  the  current  A  C,  after  which,  it  would  undergo  feveral 
ofcillations  previous  to  acquiring  a  ftate  of  equilibrium  and  repofe.  But  the  current  A  C 
continues  its  lateral  a£lion  :  a  fecond  time  it  draws  away  the  water  through  C  D  into  E,  and 
forces  it  to  renew  its  motion  through  the  curve  C  D  E;  in  which  manner  the  eddy  continues 
without  ceafing. 

If  the  river  fhould  pafs  through  a  contraftion  of  its  bed  at  N,  it  will  produce  eddies  on  both 
fides,  atP  and  at  Q,  fimilar  to  thofe  we  have  contemplated  at  D  C. 

Suppofe  the  ftream  of  water,  after  having  ftruck  the  bank  G  H,  to  be  reflected  into  a  new 
diredtion  H  S,  tlie  lateral  communication,  of  motion  will  excite  eddies  in  the  angle  of  reflec- 
tion R. 

When  two  currents  of  unequal  velocity  meet  obliquely  in  the  middle  of  the  river,  the  moft 
rapid  current  will  produce  eddies  in  that  which  is  the  leaft  rapid. 

Suppofe  a  ftream  of  water  to  flow  over  a  bed  of  unequal  depth.  If  the  longitudinal  fcflion 
of  the  inequalities  of  the  bottom  exhibit  a  gentle  flope,  as  at  A  B  C,  fig.  20.  the  fuperior 
water  will  imprcfs  its  motion  by  lateral  communication  upop^he  inferior  water,  which  is  near 
the  bottom,  beneath  the  line  A  C,  and  a  current  will  take  place  through  the  whole  depth  of 

the 


EffeBs  of  Eddies y  ^c.  on  the  Motion  of  Riven.  45)3. 

the  feftion  M  B.  The  current  which  is  formed  near  the  bottom  at  B,  is  turned  out  of  its 
courfe  by  the  flope  B  C,  and  proceeds  to  rife  above  the  furface  at  Qj  fometimes  in  the  form 
of  a  curling  wave  or  vertical  v/hirlpool.  If  the  extremities  of  the  hollow  place  form  an 
abrupt  angle,  as  D  E,  F  G,  eddies  will  be  produced  even  at  the  bottom,  in  the  vertical  direftion 
at  D,  and  fometimes  alfo  at  G.  Thefe  phenomena  may  be  obferved  in  an  artificial  channel 
with  glafs  fides. 

Every  eddy  de/iroys  apart  of  the  moving  force  of  the  current  of  the  river.  For  the  water  which 
defcends  by  a  retrograde  motion,  in  the  inclined  plane  C  D  E,  fig.  19.  cannot  be  reftored  in 
the  direftion  of  the  current  of  the  river  but  by  a  new  impulfe.  It  is  as  it  were  a  ball,  which 
is  forced  to  rife  on  an  inclined  plane,  whence  it  continually  falls  back  again  to  receive  new 
impulfions.     It  is  the  labour  of  Sifyphus. 

Hence  I  deduce,  as  a  primary  confequence,  that  in  a  river,  of  which  the  courfe  is  permanent,  and 
the  feclions  of  its  bed  unequal,  the  water  continues  more  elevated  than  it  would  have  done,  if  the  ivhole 
river  had  been  equally  contrafled  to  the  dimenfwis  of  its  fmallefl  feElion.  The  caufe  of  this  pheno- 
menon is  the  fame  as  that  which  retards  the  expenditure  through  the  tube  with  enlarged  parts. 
(Prop.  VII.  No.  4.)  The  water  which  defcends  from  the  elevation  above  the  contra£ted  part 
N,  into  the  bafon  P  Q^  fig.  19.  lofes  nearly  the  whole  of  the  velocity  it  acquired  by  defcending 
from  it ;  -becaufe  the  narrow  part  has  a  curved  flope  towards  the  lower  part  of  the  river,  which 
direfts  the  velocity  of  the  ftream  in  an  horizontal  dire£tion.  Guilielminihas  well  remarked,  that 
a  fall  does  not  influence  the  velocity  of  the  lower  ftream,  becaufe  the  eddies  of  the  water  in  the 
bafon  P  Q^deftroy  the  velocity  produced  by  the  fall.  This  velocity  increafes  the  depth,  and 
enlarges  the  width  of  the  channel  at  P  Q^  Eddies  are  formed  on  each  fide,  at  the  bottom, 
and  at  the  furface ;  both  in  the  horizontal  and  vertical  direftions.  It  would  be  to  no  purpofc 
to  atttempt  to  prevent  this  hollowing  out  and  enlargement  of  the  channel  by  fuch  a  fall,  by 
adopting  the  means  of  clofe  walls ;  for  the  bafon  would  then  obtain  its  enlargement,  where 
thefe  conftruftions  might  end. 

If  the  channel  have  a  number  of  fuccefllve  contracflions  and  dilations,  M  N,  without 
cafcade  or  dam,  there  will  ftill  be  formed,  at  each  dilatation,  eddies  which  will  diminifli  the 
\'elocity  more  than  if  the  channel  had  an  uniform  fettion  equal  to  that  in  M  or  N.  It  will, 
tiierefore,  follow,  that  the  furface  of  the  water,  after  each  dilatation,  muft  rife,  in  order  to 
recover  the  velocity  it  loft  by  the  eddies.  If  we  call  the  height  to  which  the  water  muft  rife, 
above  the  elevation  necelTary  to  have  overcome  the  retardations  of  a  bed  of  uniform  fc£llon, 
=  a,  and  that  the  number  of  equal  and  fucceflive  alternate  dilatations  and  contraftions  bte 
=  VI,  the  height  of  the  rife  in  the  ftream  thus  alternately  dilated  beyond  that  of  the  fame 
river  unifonnly  contra£led  will  be  rr  am.  I  here  fuppofe  the  bottom  of  the  river  to  be 
uniform.  If  this  bottom  be  of  fuch  a  nature  to  be  attacked  by  the  current,  the  contrafted 
parts  will  be  hollowed  out,  and  the  matter  will  be  dcpofited  in  the  enlarged  parts. 

The  fecond  confequence  which  I  draw  from  the  principle  here  eftablifhed,  refpe£ling  the 
Ibfs  of  force,  caufed  by  the  eddies,  is  of  confiderable  importance  in  the  themy  of  rivers,  and 
appears  to  have  been  neglefted  by  thofe  who  have  treated  on  this  fubjeft.  The  friftion  of  the 
water  along  the  wet  banks,  and  over  the  bottom  of  rivers,  is  very  far  from  being  the  only 
caufe  of  the  retardation  of  their  courfe,  which,  confequently,  requires  a  continued  defcent  to 

Vol.  II. — Feb.  1799.  3  S  maintain 


494  ^^w  Variety  of  argillaceous  Iron-ore. 

maintain  its  velocity.  One  of  the  principal,  and  moft  frequent,  caufes  of  retardation  in  a 
river,  is  alfo  produced  by  the  eddies,  which '  are  inceflantly  formed  in  the  dilatations  of  the 
bed,  the  cavities  of  the  bottom,  the  inequalities  of  the  banks,  the  flexures  or  windings  of  its 
courfe,  the  currents  which  crofs  each  other,  and  the  flreams  which  ftrike  each  other  with 
different  velocities.  A  confiderable  part  of  the  force  of  the  current  is  thus  employed  to  re- 
iftore  an  equilibrium  of  motion,  which  that  current  itfelf  does  continually  derange. 

(To  be  continued.) 

_^ 

No.  IV. 

■'Concerning  a  new  Variety  of  argillaceous  Iron-ore.     By  Samvel  L.  MlTCHlLL,  M.D.  of 

New  York. 
SIR, 

JL  HE  annexed  defcription  of  a  mineral  fubftance,  and  the  remarks  upon  it,  are  taken,  by 
permiffion,  from  Dr.  Mitchill's  manufcripts.  As  the  fubje£i;  appears  to  me  worthy  to  be 
made  known  to  the  mineralogills  of  Europe,  I  have  forwarded  you  a  copy  for  publication,  in 
your  ufeful  and  inftrudive  Journal ;  I  have  the  fatisfa£tion  to  inform  you  at  the  fame  time, 
that  Mr.  Bruce,  a  young  gentleman  who  goes  paflenger  to  London  in  the  fame  fhip  which 
■conveys  this  note,  is  in  poffeffion  of  a  fpecimen  of  this  reiaarkable  foflil. 

I  am.  Sir, 

Your  very  obedient  fervant,  ■ 
Neiv-Tork,  November  x-j,   1798.  ADOLPH.  C.  LENT,  M.D. 

To  Mr.  W.  Nicholfon. 


ut  new  Variety  of  Iron-ore  of  the  argillaceous  E^ind,  and  figured  fomewhat  Hie  Bafaltes. 

The  fpecimen  of  cohimnar  iron-ore  in  my  colleftion  is  from  Germany,  and  correfponds 
very  well  with  Mr.  Kirwan's  fecond  variety  of  his  firfl;  family  of  argillaceous  iron-ores- 
(a.  Elements  of  Mineralogy,  Dublin,  1 796.)  I  knew  of  no  other  iron-ore  of  that  charafter, 
until  a  few  months  ago.  As  I  was  walking  on  my  farm  upon  Long-ifiand,  furveying  the 
various  mineral  produ£lions  that  lay  thick  under  my  feet,  I  obfcrved  a  fmail  fpot,  that  ap- 
peared to  be  paved,  with  ftones  of  a  regular  figure  ;  on  taking  up  fonie  of  them  and  exa;j)ining 
them,  they  were  evidently  of  the  fame  conftitution  with  the  common  argillaceous  iron-ftone, 
which  lay  fcattered  about  in  rude  lumps.  They  were,  however,  of  a  fingular  Ihape.  They 
were  about  four  inches  long ;  and  ftood  erect,  fide  by  fide  of  each  other,  in  a  iliff  loam.  Each 
of  them  had  five  fides  and  five  angles  ^  and  though  not  exaiSt  pentagons,  were  readily  dif- 
tinguilhable  in  moft  of  the  fpecimens  from  one  end  to  the  other.  This  fhape  was  moft 
perfeft  at  the  two  ends,  which  were  confiderably  larger  than  the  middle  part,  and  about  one 
inch  and  a  half  acrofs.  So  that  when  a  fpecimen  of  this  ore  was  grafped  in  the  hand,  it  had 
ibme  refemblance  of  a  double-headed  peftle.  In  fome,  however,  four  fides  only  were  to  be 
traced. 

The 


Origin  of  Sdfaft'es  ? — Ekcir'ical  Doubler.  495 

Tfie  number  of  tKefe  figured  bodies  was  about  thirty-fix,  though  not  all'  of  them  equally 
perfeft.  And  they  evidently  had  been  formed  from  a  folid  circular  mafs  of  argillaceous  iron- 
ore,  of  about  two  feet  and  five  inches  in  breadth,  and  four  inches  in  tliicknefs,  at  the  central 
parts,  and  becoming  thinner  towards  the  edges.  In  the  natural  fra<flure  of  t}ie  ftone,  the 
fragments  took  upon  themfelves  thefe  regular  forms,  very  much  refembling  bafaltes ;  and, 
like  bafaltes,  \hoi\^  figured  they  evidently  are  not  cr^allizedy  for  they  are  as  perfectly  terri- 
genous and  opaque  as  any  argillaceous-  ore  of  iron  whatfoevcr. 

I  brought  away  fome  of  the  pentagonal  pieces,  and  could  eafdy  get  more  of  them,  for  ia 
taking  out  the  few  that  I  brought  away,  I  difturbed  the  reft  as  little  as  poffible. 

Do  not  thefe  fpecimens  go  very  far  towards  deciding  the  difpute,  if  any  doubts  ftill  re- 
main, about  the  igneous  or  aqueous  origin  of  bafaltes  ?  they  fupport,  by  the  moft  powerful 
evidence,  the  Neptunian  origin  of  that  kind  of  figured  bodies,  and  are  direftly  oppofed  to  the- 
Plutanic  fyftem.  The  fpecimens  before  me  prove,  that  argillaceous  iron-ore,  which  nobody 
has  fuppofed  to  be  a  volcanic  produftion,  can  take  on  a  bafaltic  figure.  AVith  Bergman, 
Weideman,  and  Kirwan,  I  am  inclined  to  believe  the  weight  of  teftimony  is  oppofed  to  the 
formation  of  bafaltic  columns  by  rusiON,  and  that  the  true  manner,  in  which  many,  if  not  all, 
of  them  have  been  produced,  is  in  the  moist  way.  This  new  proof,  added  to  Mr.  Kirwan's 
very  able  paper  on  traps  and  bafaltes.^  I  think  fettles  the  controverfy  in  his  favour. 


V. 

Conceraing  the  Invention  of  the  Electrical  Doabler.     By  Mr.  JoHN  READ. 

To  Mr.  NICHOLSON. 
SIR, 


I 


N  your  journal,  Nov..  1 798,  page  368,  you  charge  me  with  want  of  candour,  in  my  de- 
fcription  of  what  I  call  the  fpedlacle  doubler  of  eleftricity.  Whether  this  charge  be  juft,  or 
not,  muft  be  left  to  the  decifion  of  a  judicious  public:  who,  it  i*  hoped,  will  have  candour 
enough  to  compare  your  account  of  the  doubler  with  mine.  I  was  of  opinion,  that  after 
giving  you  the  priority  of  invention,  which  I  have  exprefsly  done  in  page  29  of  my  work, 
entitled  Summary  View  of  the  fpontaneous  Electricity  of  the  Earth  and  Atmofphere,  no 
further  acknowledgement  could  be  required.  The  paflage  is,  "  and  to  give  the  plates  a  con- 
fiderably  more  extended  infulation  than  that  made  by  Mr.  Nieholfon,  without  augmenting 
the  fize  of  the  inftrument,  Set." 

That  your  charge  is  frivolous,  will  more  fully  appear  from  the  following  circumftance, 
namely,  that  Dr.  Prieftley  did  aiftually  deliver  my  original  manufcript  into  your  hands,  with 
full  power  to  corredl,  erafe,  or  add  whatever  you  chofe,  and  after  you  had  retained  it  more 
than  three  months  in  your  pofleflion,  I  received  the  manufcript  from  you,  and  found  that  you 
had  made  no  alteration  at  all  in  it:  of  courfe  it  went  to  tlie  prefs  in  the  drefs  it  is  now  in. 

It  is  not  my  intention,  at  prefent,  to  criticife  on  all  you  have  faid  in  the  paflage  alluded  to. 
As  to  the  adopting  fome  of  your  own  words  into  my  defcription,  of  nearly  the  fame  inftrument, 
could  not  well  be  avoided;  nor  can  It  be  thought  an  illiberal  proceeding.     But  if  you  difliked 

3  S  2  it-~ 


49<>  Conccfning  the  revolving  DoubUr  of  EkBrickf, 

it — if  you  thought  it  improper,  you  ought  to  have  mentioned  it  at  a  proper  time,  viz.  when 
you  returned  the  manufcript,  or  before  it  was  fent  to  the  prefs  ;  and  your  requeft  would  have 
been  .literally  complied  with.  With  regard  to  the  inftrument  itfelf,  it  is  at  prefent  ufelefs; 
and  it  is  allowed  by  all,  that  it  has  totally  failed  for  want  of  a  perfedl  infulation.  If  this  de- 
fe£i:  fhould  at  fome  future  time  be  overcome,  the  doubler  of  ele£lricity,  will  then  be  tlie  moft 
ufeful  and  the  moft  noble  inftrument  in  the  whole  group  of  electric  apparatus. 

I  remain,  fir, 

Your  very  humble  fervant, 

JOHN  READ. 

^aJrant,  in  Knight/bridge  , 
January  i  "jth,  1 799. 


"Though  the  above  letter  relates  to  perfonal  incidents,  which  may  not,  perhaps,  be  confidered 
with  any  great  degree  of  intereft,  yet  I  conceive  my  readers  will  admit  the  propriety  of  publifli- 
ing  it,  in  order  that  Mr.  Read,  whofe  candour,  as  an  author,  has  been  called  in  queftion,  may 
juftify  himfelf  to  that  public,  which  he  has  eflentially  ferved  during  a  long  life,  employed  as  an 
inftrument-maker  and  operative  philofopher.     I  am  well  content,  that  the  declfion  refpedting 
the  doubler,  Ihould  be  made  by  the  tribunal  to  which  he  refers,  and  to  which  it  of  right 
belongs.     If  a  careful  review  of  what  I  have  written,  together  with  his  prefent  communica- 
tion, had  led  me  to  alter  my  fentiments,  it  would  be  my  duty  to  fay  fo  in  this  place.     But  I 
think  I  have  faithfully  ftated  the  fafts  in  the  paflage  he  alludes  to,  and  have  only  to  remark, 
that  the  indireft   mention    of  my  name,  in  page  29  of  his  work,  was   little,  if  at  all, 
calculated  to   deftroy  the  conclufion  which  his  readers   would   obvioufly  be  induced    to 
make,  from  the  unacknowledged  copy  in  the  former  part  of  the  chapter;  in  proof  of  which, 
the  inference  of  the  foreign  philofophers,  who  were  mifled  in  his  favour  as  the  inventor,  is 
nearly  decifive.     His  narrative  refpe£ting  my  having  pofleffed  his  manufcript,  previous  to 
its  publication,  is  not  quite  correal  in  the  manner,  becaufe  it  does  not  communicate  the 
whole  of  what  happened.     Either  Dr.  Prieftley,  or  elfe  Mr.  Read  with  the  Doftor's  recom- 
mendation, did  deliver  to  me  certain  manufcripts  about  fix  or  feren  years  ago,  which  I  believe 
to  have  been  part,  or  the  whole,  of  what  was  fince  publiftied,  under  tlie  title  of  A  Summary 
Vienv,  i^c.  but  they  were  not  put  into  my  hands  with  the  notion  that  any  relation  might 
fubfift  between  me  and  their  contents,  which  could  require  the  full  powers  Mr.  Read  men- 
tions •, — but  fimply  to  corre£t  and  prepare  them  for  the  prefs,  on  condition  of  being  paid 
for  my  labour.     As  I  have  always  declined  this  kind  of  employ,  excepting  when  motives  of 
perfonal  acquaintance  or  friendlhip  have  led  me  to  it,  I  returned  tliis  copy  untouched,  and 
unperufed,  to  the  author,  and  fuppofed  of  courfe,  that  he  had  employed  fome  other  perfon  to 
revife  it.     I  hope  and  believe,  therefore,  that  notwithftanding  this  incident,  upon  which  Mr. 
Read  feems  to  place  fo  much  reliance,  it  cannot  be  tliought  to  afford  any  ground  for  an  infi- 
xiuation,  that  I  have  been  induced  to  fpeak  as  I  have  done,  of  his  fliare  in  the  invention  of  the 
doubler,  from  any  motives,  but  fuch  as  ought  to  guide  an  independent  narrator  of  philofophi- 
cal  fads. 

With 


BleUrlcal  DouUer-^Cofi'efpondmce,  i|o« 

With  regard  to  the  inflrument  itfelf,  which  is  fo  truly  honourable  to  the  fagacity  of  Llch- 
tenberg,  Klincock,  Volta,  and  Bennett,  but  in  which  my  fliare  is  certainly  very  trifling,  I  do 
not  know  that  its  imperfedions  are  greater  tlian  was  long  fince  afcertained  by  the  Englifli 
ele£lricians -,  of  which  an  account  is  given  in  a  paper,  at  page  394  of  the  firft  volume  of  this 
Journal.  If  Mr.  Read  is  in  pofleflion  of  any  new  fads  refpeding  its  operation,  the  public 
will,  no  doubt,  receive  them  with  as  much  attention  and  refpefl:,  as  they  have  paid  to  the  re- 
fults  of  his  former  purfults. 


VI. 

Inqmnes  refpeEling  the  CcnflrttB'ton  of  a  Water-wheel,  and  the  ManufaBure  of  Bricks. 

By  a  Correfpondent. 

Mr.  Nicholfon  will  oblige  a  friend  to  his  ufeful  Journal,  by  giving,  therein,  information  on 

the  under  points. 

December,  1798. 


o, 


'N  a  ftream  where  the  fall  is  61-  feet,  what  diameter  ought  the  water-wheel  to  be? 

Whether  a  bucket-wheel,  or  float-board-wheel  ? 

If  the  former,  ought  the  water  to  be  brought  in  at  the  height  of  the  fall;  or  a  portion  given 
for  head  ?  and  what  portion .? 

Is  there  any  pradical  direftion  in  print,  to  dired  the  procefs  of  brick-making  ? 

If  there  is  not,  Mr.  N.  would  do  a  material  fervlce  to  numbers,  who  are  in  fome  parts  of  the 
country,  remote  from  the  workmen  who  are  Ikilled  in  this  art,  by  colleding  and  publilhing 
fuch  pradical  direflions  of  the  nature  of  the  materials  and  the  procefs,  as  will  enable  the  un- 
informed to  fupply  themfelves  with  this  ufeful  article. 


The  data,  refpefting  the  above-mentioned  ftream,  are  not  fufiiciently  precife  to  determine 
whether  a  bucket-wheel,  or  float-board-wheel,  would  be  preferable :  the  quantity  of  water 
aflx)rded  per  minute  ought  to  have  been  mentioned.  The  bucket-wheel  appears,  upon  the 
whole,  to  be  beft  adapted  to  fmall  ftreams  of  water  with  a  confiderable  fall ;  but,  in  contrary 
circumftances,  the  clofe  breaft-Wheel  appears  to  be  preferable,  that  is  to  fay,  a  wheel  with 
float-boards,  moving  in  a  channel  fo  well  fitted,  as  to  permit  the  leaft  poflible  quantity  of 
water  to  efcape,  without  afting  upon  the  wheel. 

The  diameter  of  the  wheel  may,  in  theory,  admit  of  confiderable  variation.  Admitting  it 
to  be  a  breaft-wheel,  its  radius  muft  be  fomewhat  more  than  the  height  of  the  fall.  The  ve- 
locity of  the  furfacc  of  fuch  wheels,  as  are  driven  by  the  gravitating  power  of  water,  lies  be- 
tween two  feet  and  fix  feet  per  fecond.  Three  feet  may  be  confidcred  as  a  good  pra£lical 
velocity,  as  determined  by  experience.  It  is  of  no  advantage,  but,  on  the  contrary,  a  lofs, 
to  confume  any  part  of  the  head,  in  throwing  the  water  againft  the  floats  with  a  confiderable 
impulfe ;  it  is  only  neceflary  that  the  ftream  fliould  be  delivered  upon  the  wheel  with  fome- 
what 


498  -Art  of  Sricl-maihtg. — Combiijlkn  of  Phofphartis. 

what  rtiore  velocity  than  that  of  the  wheel  itfclf.  If  the  ftream  can  be  brought  on  with  the 
velocity  of  three  feet  at  the  top  of  the  fall,  it  will,  undoubtedly,  be  befl ;  but  if  the  watef 
(hould  flow  from  a  pond,  having  no  perceptible  current,  the  portion  or  fpace  required  to  pro- 
duce this  velocity  will  be  about  one  foot  and  a  half. 

Thefe  remarks  are  equally  applicable  to  bucket  or  overfhot  wheels. 

The  art  of  brick-making  is  concifely  defcribed  in  the  French  Encyclopedie.  Bergmanrt 
has  attended  to  this  fubjed  in  a  direft  chemical  way.  A  tranflation  of  his  treatife  intcS 
Englilh,  may  be  fecn  in  the  third  volume  of  his  Phyfical  and  Chemical -Eflays ;  or  an  abridge- 
ment of  the  fame  in  my  Chemical  Diftionary,  article  Brick.  As  the  art  itfelf  is  of  extenfive 
utility,  and  of  confiderable  fimplicity  in  the  pradice,  I  fhould,  in  this  place,  have  defcribed 
the  procefs,  with  remarks,  if  I  were  not  defirous  of  again  infpefling  the  methods  which  are 
pradifed  in  the  neighbourhood  of  this  metropolis.  When  I  fhall  have  done  this,  the  account 
he  defires  will  appear. 


Ui 


sm. 


VII. 

On  the  Combiijlion  of  Phofphorous, 

To  Mr.  NICHOLSON. 


PON  putting  a  fmall  piece  of  phofphorus  in  a  {hovel  over  the  fire,  in  fome  experiments 
I  lately  made  for  the  entertainment  of  a  company  of  friends,  that  fubitance  fmoked,  began 
to  melt,  and  took  fire  as  ufual.  When  the  combuftion  had  ceafed,  and  we  were  looking  at 
the  ruddy  coloured  refidue,  or  acid,  one  of  the  company  wetted  the  refidue  by  fpltting  upon 
it  i  at  which  inltant,  the  combuftion  was  renewed,  with  a  crackling  noife,  at  every  part  where 
the  moifture  had  reached.  I  fuppofe  the  refidue  to  have  been  oxygenated  phofphorus,  or 
phofphoric  acidj  and  that  the  addition  confifted  chiefly  of  hydrogen  and  oxygen.  What  then 
was  the  new  combination,  which  was  attended  with  the  farther  extrication  of  heat  ?  Will 
you  have  the  goodnefs  to  explain  this  faii,  or  fubmit  it  to  your  correfpondents. 

I  am,  Sir, 

Your  obliged  reader, 
January  4,  1 7^9.  ,  R.  S* 


I  have  complied  with  the  requeft  of  this  correfpondent,  by  publifliing  his  letter ;  upon 
which  my  crther  friends  will  make  their  remarks,  if  the  fubjcdt  fhould  appear  to  require  it. 
If  phofphoric  acid,  at  an  elevated  temperature,  in  contaft  with  iron,  can  be  made  to  emit  heat 
and  light  by  the  addition  of  water,  as  R.  S.  apprehends,  the  true  explanation  of  the  play  of 
affinity  mull  be  fought  from  varied  experiments,  in  which  all  the  products,  as  well  gafeous 
as  fixed,  Ihould  undergo  examination.  But  in  the  inftance  before  us,  I  am  much  inclined 
to'  think  the  renewed  combuftion  is  produced  by  a  portion  of  phofphorus,  which  efcaped 
the  atmofpheric  action  in  the  firft  burning.     That  is  to  fay,  when  a  piece  of  phofphorus  i& 

burned. 


On  ihe  mperfeEl  cf  Jloiu  tranfttion  of  Heat  through  Charcoal,  499 

burned,  in  the  clrcumftances  of  the  prefent  experiment,  the  upper  or  greateft  part  of  the 
mafs  becomes  acidified,  and  covers  a  portion  beneath,  fo  as  to  prevent  that  lower  part  from 
combining  with  the  atmofpheric  oxygen ;  in  confequence  of  which,  tlie  combuftion  ceafes 
before  the  whole  is  burned.  But  when  this  denfe  acid  becomes  diluted  with  water,  it  boils, 
and  mod  probably  rifes,  at  leaft  fo  far  as  to  leave  the  furface  of  tlie  phofphorus  below 
uncovered,  and  to  permit  the  combuftion  to  be  renewed.  Inftances  of  volatility  being  given 
to  various  fubftances  by  water,  are  fufficientiy  numerous  in  chemillry ;  of  which  tlie  acid  of 
borax  is  one  of  the  moft  ftriking.  To  what  degree,  the  fame  effect  may  take  place  in  the 
phofphoric,  I  am  not  aware.  Scheele  (on  Air  and  Fire,  §.  73),  indeed,  affirms,  that  water  gives 
it  fixity ;  but  he  fays  this  in  fo  loofe  a  way,  that  I  am  not  dlfpofed  to  rely  on  the  affertion,  as 
nniverfally  true,  in  contradiftion  to  fome  other  fafts,  which  fhew  tliat  the  diluted  acid  does 
partly  rife  by  heat. 

VIII. 

Pyrometr'ical  EJfays  to  determine  the  Point  to  which  Charseal  is  a  Non-cofiduclor  (f  Heat. 

By  Citizen  GuTTON*. 


s. 


'INCE  the  experiments  and  refearches  of  philosophers  have  been  directed  to  the  matter  of 
heat,  the  flate  in  which  it  is  found,  and  the  various  manners  in  which  it  affedts  bodies,  it 
has  been  well  afcertained  that  charcoal  is  one  of  die  worft  conductors  of  heat.  From  this- 
obfervation  it  has  been  propofed  to  form  a  double  wall  to  furnaces,  and  to  fill  the  in- 
termediate fpace  -with  charcoal ;  and,  very  recently,  an  happy  application  of  this  property  has 
been  made  in  the  conftrudtion  of  veffels  defigned  for  the  preferving  the  temperature  of  warm 
infufions. 

I  am  not,  however,  acquainted  with  any  refearches  which  may  have  been  matle  to  fix,, 
even  comparatively,  the  limits  of  this  kind  of  infulation.  The  effe£t  of  the  non-condu£ting 
power  of  charcoal  has  been  fo  (lightly  confidered,  even  by  the  moft  accomplifhed  chemifts, 
that  they  have  not  tliought  it  neceffary  to  take  any  account  of  this  effect  in  the  refult  of  their 
operations.  Hence  it  is,  that  the  celebrated  Klaproth,  in  a  fei-ies  of  experiments  upon  the 
aJteration  which  ftones  undergo  when  expofed  to  extreme  heat,  feems  to  think  that  the 
heat  might  have  been  nearly  equal  in  fuch  as  were  contained  in  crucibles  of  porcelain,  and 
tliofe  which  were  entirely  furrounded  with  charcoal.  The  redudion  of  the  oxides  of 
tungften,  titanium,  and  uranium,  has  alfo  been  attempted  in  crucibles  of  charcoal,  though  it  is 
well  known  that  the  higheft  degree  of  heat  is  here  required  for  tlie  fuCon,  and  that,  in  other 
rcfpects,  every  endeavour  muft  be  made  to  expofe  them  to  the  moft  intenfe  ignitioai. 

Thefe  reflections  have  led  me  to  conclude,  that  it  might  be  of  fome  importance  to  ebtain 
a  more  accurate  meafure  of  this  infulating  effe£t  of  charcoal.  The  following  are  die  experi- 
ments which  I  have  made  upon  this  fubjedt. 

Out  of  the  fame  parcel  I  took  two  pyromctic  pieces  perfecily  alike,  and  pbced  one,  which 
Iflliall  call  A,  in  a  crucible  filled  with  pure  filiceous  fand  dried  over  the  .fiire.     The  crucible 

•  Read  to  the  French  National  luftitnte,  6th  Germinal,  in  ths  6th  year  of  the  Republic  (March  zS,  1798), 
and  inferwd  in  the  Annales  de  Chimie,  XXVI.  225. 

was 


J  00  Difficulty  of  tranfmlttingjlrong  Heat  through  Charcoal. 

was  8  decemeters  high,  6  in  diameter  at  the  mouth :  the  cylinder  of  clay  was  placed  la 
the  middle,  and  the  crucible  had  its  cover  luted  on. 

The  other  piece,  B,  was  placed  in  a  fimilar  crucible,  with  this  difference,  that  the  crucible 
was  filled  with  powder  of  charcoal,  which  had  been  previoully  ignited  in  a  clofe  crucible. 

The  two  crucibles  were  then  placed  befide  each  other  on  the  grate  of  a  large  melting 
furnace,  in  which  the  fire  was  kept  up  for  about  three  quarters  of  an  hour. 

When  the  crucibles  were  cooled,  the  cylinder  A  was  taken  out  of  the  fand,  and  prefented 
to  tlie  pyrometic  fcale  of  Wedgewood  ;  it  had  undergone  a  contraction  of  89  degrees.  The 
cylinder  B  was  then  taken  out  of  the  charcoal,  and  Hopped  in  the  gage  at  60,25  degrees. 
It  had  acquired  a  grey  tinge,  but  without  any  appearance  of  glazing. 

Hence  it  follows,  that  the  tranfmiffion  of  heat  through  the  fand,  is  to  the  tranfmiffion 
through  the  charcoal  nearly  in  the  proportion  of  3  to  2.  In  proportion  as  this  difference 
is  in  itfelf  ftriking,  the  more  it  becomes  neceffary  to  attend  to  fuch  precautions  as  are  re« 
quired  to  prevent  deception  arifing  from  foreign  circumftances.  The  crucibles  had  moft 
affuredly  undergone  the  fame  degree  of  fire.  The  flate  m  which  they  were  found  exhibited 
the  traces  of  its  aftion :  the  conditions  were  tlierefore  as  equal  as  poffible ;  but  it  might, 
poffibly,  be  fufpe£ted  that  fome  defe£t:,  or  want  of  uniformity  in  the  pyrometic  piece,  or 
fome  imperfedtion  in  its  compofition,  or  fabrication,  might  have  altered  its  difpofition  to 
contraci:  equally,  and  proportionally  to  the  heat  it  might  undergo.  There  was  a  very  fnnple 
method  of  removing  thefe  doubts ;  namely,  to  afcertain  whether  the  fame  piece  put  into 
the  fand,  and  expofed  to  a  much  ftronger  heat,  would  refume  the  common  courfe  of  con- 
traction, and  agree  with  the  former.  This,  in  fa£t,  was  performed ;  the  fame  two  pieces, 
A  and  B,  were  inclofed  in  one  and  the  fame  crucible  filled  with  fand,  fo  that  they  were  not 
more  diflant  from  each  other  than  about  7  or  8  millimetres,  and  the  crucible  was  expofed 
for  half  an  hour  to  the  moft  violent  heat  of  a  forge,  urged  by  three  twyers. 

The  crucible,  when  cold,  was  found  to  have  loft  fome  of  its  thicknefs  by  vitrification,  fo 
that  there  was  a  crack  in  one  of  its  fides.     The  fand,  however,  was  not  deranged  within. 

The  piece  A  marked  163,5  "pon  the  pyrometic  fcale,  it  weighed  no  more  than  1,491 
grammes ;  its  fpeclfic  gravity  was  2,232. 

The  piece  B  exhibited  160  degrees  on  the  pyrometer,  it  weighed  1,53  grammes,  and  its 
fpeclfic  gravity  was  2,346.  It  had  almoft  loft  the  grey  tinge  which  it  had  acquired  in  the 
charcoal,  and  was  no  longer  diftingulfliable  from  the  other  but  by  a  black  vitreous  point, 
produced  by  the  acceflion  of  fome  foreign  matter. 

I  confefs  I  did  not  expe£t  to  be  fo  completely  fuccefsful  in  this  verification  :  the  fmall 
difference  of  3 '  degrees  is  nothing,  when  we  confider  that  the  piece  firft  inclofed  in  the 
charcoal,  and  which  had  ftopped  at  60,  was  ftill  capable  of  contracting  through  an  additional 
1 00  degrees.  It  is,  befides,  known  to  be  phyfically  impoffible,  that  two  bodies  placed  in 
the  fame  crucible,  and  in  contaCt  with  the  fame  fubftance,  fhould  be  ftriCtly  in  the  fame 
fituation  as  to  the  reception  of  heat,  particularly  when  the  blaft  is  directed  from  three  differ- 
ent nozzles,  which  are  neceffarily  unequal.  The  advanced  ftate  of  one  of  the  fides  of  the 
crucible,  with  refpeCt  to  the  fufion,  is  a  proof  that  this  was  in  fa£t  the  cafe. 

We  may  therefore  conclude  from  thefe  effays,  that  the  body  included  in  the  charcoal  in 

the 


ImperfeB  Conduclltig'pofvey  of  Charcoal. — New  Air-pump.  ^oT 

the  fame  fire,  does  not  receive  more  than  about  two-thirds  of  the  heat  of  a  body  furrounded 
with  quart7ofe  fand ;  that  the  reduction  of  metals  which  do  not  flow  at  a  lower  degree  of 
heat  than  130  degrees,  cannot  be  effefted  in  charcoal ;  that  the  pyrometric  pieces  do  not  af- 
ford an  accurate  judgment  of  the  heat  communicated,  unlefs  they  be  in  contaft  with  fub- 
ftances  of  the  fame  kind  as  thofe  which  furround  the  body,  on  which  the  chemical  procefs  is 
performed ;  and  laftly,  that  with  thefe  attentions  we  may  make  an  advantageous  afe  of  this 
inftrument,  of  which  the  applications  will  not  be  fufficiently  known,  until  we  fhall  be  able 
to  procure,  at  pleafure,  cylinders  fabricated  after  the  manner  of  Wedgewood,  of  a  clay  fuf- 
ceptible  of  lofing  0,18  of  its  volume  by  contraction  ;  or,  which  is  the  fame  thing  (fuppofing 
po  elaftic  matter  to  fly  off),  of  paffing  from  the  fpecific  gravity  of  2,05  to  2,45,  between  the 
degree  of  ignition  required  for  baking  the  bifcuit  of  earthen  ware,  and  the  higheft  heat  ef 
furnaces,  without  undergoing  a  commencement  of  fufion. 

I  have  made  a  great  number  of  experiments,  with  the  intention  of  difcovering  a  clay 
which  might  naturally  exhibit  thefe  properties,  or  which  might  acquire  them  by  eafy  and 
cheap  preparation.  I  hope  I  {hall  be  fhortly  able  to  communicate  fatlsfadlory  refults  to  the 
clafs  of  the  inftitute. 


IX. 

]Defcripthn  of  an  Air-pump,  of  a  neiv  ConflruB'ton.     By  the  Rev.  JaMES  LiTTLE,  of  Lachtty 

m  the  County  of  Mayo,  in  Ireland*. 

HE  pump  here  defcrlbed  is  a  portable  one,  contrived  fo  as  to  be  confined  in  a  very 
fmall  fpace  ;  but  the  author  obferves,  that  it  may  be  made  of  a  different  form,  and  with  two 
barrels,  though  not  conveniently. 

Fig.  I.  plate  XXI.  Is  a  perfpeftive  view  of  the  whole  machine,  as  it  lies  before  the 
operator.     Fig.  2.  is  a  back  view  of  the  fame. 

-  The  barrel  A  A  (fig.  i.)  is  almoft  fifteen  inches  long,  and  internally  in  diameter  juft  two 
inches.  The  plfton  (fig.  3.)  is  folid,  without  any  perforation ;  it  confifts  of  circular  plates 
of  leather,  prefled  together  between  the  round  plate  a  (in  the  focket  of  which,  b,  the  pifton 
rod  was  Inferted,  and  faftened  by  a  crofs-fcrew,  before  the  leathers  were  put  on),  and  the  two 
upper  plates  c  and  d ;  of  which  the  outer  one,  d,  being  fcrewed  upon  a  fcrew  formed  on  the 
outfide  of  the  focket,  prefl'es  down  the  under  plate,  and  this  the  leathers,  which  latter  are 
not  reprefented  in  the  figure.  The  upper  plate,  when  fcrewed  on,  lies  even  with  the  upper 
part  of  the  focket,  that  when  the  piflon  is  raifed  to  the  top,  it  may  touch  the  plate  covering 
the  upper  part  of  the  barrel,  leaving  no  air  above  the  pifton.  Thefe  two  plates  of  the  pifton, 
cfpecially  the  lower  one,  are  made  fo  large  as  juft  to  move  in  the  barrel  without  touching 
it,  and  care  was  takeft  that  when  the  pifton  is  put  down,  it  fhould  be  every  where  in  contacl 

'*  Iriili  Tranfaflions.  VI.  319.  The  paper  from  which  the  above  is  abftra£led,  could  not  be  civen  on 
account  of  its  extent.  It  occupies  77  pages.  Some  of  the  early  air-pumps  were  made  with  an  horizontal 
fcarrel.  There  is  a  plate  of  one  in  Senguerdii  Phiiofophia  Naturalis,  the  ftcond  edition  of  vvhicli,  in  410,  was 
publiflied  at  Leyden,  1685. 

VoL.II.— Feb.  i79p.  5?  ,  with 


504  Dejcriptkn  of  (tnmu  Air-ptmp, 

with  the  plate  at  the  bottom  of  the  barrel,  tliis  plate  being  turned  in  the  lathe  upon  the  piftoit 
rod,  which  fitted  its  focket  exaftly,  fo  that  not  the  leaft  fpaee  might  be  left  for  lodgment  of  air- 
under  the  pifton.  The  leathers  are  of  the  beft  buck-fkin,  dreffed  in  the  ufual  manner,  finn 
in  its  texture,  but  not  harih  ;  and,  being  well  dried,  were  foaked  in  a  mixture  of  three  parts, 
fuet,  melted  with  one  part  oil,  before  tliey,  were  put  together  :  they  were  tlien,  when  cold^. 
turned  in  a  latlie  on  the  pifton  with  a^  very  fliarp  tool  *. 

The  cylindrical  iron  rod  of  tlie  pifton  is  well  finifhed,  and  moves  through  a  collar  of  leathers.. 
As  it  is  altogether  neceffary  that  this  rod  fhould  move  molt  exactly  in  the  middle,  or  axis,  of  . 
the  barrel,  care  was  taken  that  the  pofition  of  the  box,  and  of  the  focket  annexed  to  it,  fhould 
be  fecured,  by  having  a  prominent  part  of  the  plate  of  the  box  of  leathers  inferted  into  the 
pump  barrel,  and  a  like  projecting  part  of  the  lid  of  the  box  inferted  into  the  box  itfelf ;  alfo 
that  the  pifton  rod  fhould  molt  exactly  fill  the  focket  in  the  lid.  Over  the  collar  of  leathers, 
within  the  box,  lies  a  tinned  brafs  plate,  which  is  prefled  down  upon  them  by  the  ends  of 
three  fcrews  3  3,  fcrewed  through  the  lid  of  the  box. 

The  pifton  is  moved  up  and  down  by  the  toothed  flat  bar,  or  rack,  F,  whofc  end  is  fur- 
niftied  with  an  arm  G  (to  be  taken  oiF  occafionally),  which  arm  is  fecured  againft  a  flioulder 
formed  on  the  end  of  the  pifton  rod  by  a  nut  H  fcrewed  on  the  rod ;  tlae  rack  is  moved  by  a 
fmall  fteel  wheel  L,  of  twelve  teeth,  turned  by  the  handle  X  on  its  axis  L.  This  wheel  is 
fuftained  by  the  cheeks  |K  K,  fig.  i.  and  2.  furnilhed  with  projedling  fockets,  through  which 
its  axis  pafles,  and  thefe  cheeks  are  fcrewed  to  the  iron  bar  M,  which  is  a  part  of  the  frame 
fupporting  the  whole  machine ;  by  this  bar  it  is  faftened  by  clamps  to  whatever  table  it  is 
placed  on.  From  the  middle  of  the  bar,  and  at  right  angles  with  it,  extends  horizontally  an 
arm  N  (rivetted,  and  brazed  upon  the  bar),  the  under  furface  of  the  arm  being  on  a  level  with 
the  upper  one  of  the  bar ;  this  arm  fupports  the  gage-glafsY,  and  terminates  in  a  crofs-piece 
(making  together  the  form  of  the  letter  T),  to  which  piece  and  to  the  arm  the  receiver-plate  is 
fcrewed  by  fcrews  underneath,  inferted  into  its  thick  margin. 

The  bar  M  fupports  the  upright  pieces,  or  pillars,  0,  0,  terminating  in  the  femicircular  arms 
py  pi  on  which  the  barrel  is  faftened  by  four  fcrews  at  py  p,  fcrewed  a  little  way  into  its  pro- 
jefting  rings.  Thefe  pillars  are  made  of  iron,  and  very  ftrong,  being  half  an  inch  in  thick- 
nefs ;  they  are  alfo  moft  firmly  fixed,  and  fhould  be  brazed  in  the  bar  which  fupports  them  j 
this  being  neceffary,  as  all  the  force  of  the  handle  of  the  wheel,  by  which  the  rack  is  worked, 
bears  againft  thefe  pillars ;  and  if  they  were  to  be  fhaken,  the  cement,  by  which  the  re- 
ceiver-pipe is  connefted  with  the  pump,  wohW  be  broken,  which  cannot  otherwife  happen. 
Thefe  pillars  fupport  alfo  the  iron  cafe,  or  fheath,  P  P,  extended  underneath  the  pump- 

•  If  tanned  leather  were  ufed  for  the  pifton,  &c.  it  might  be  foaked  in  oil  alone ;  but,  befides  that,  it  is 
?pt  to  grow  too  hard  by  compreflion,  and  alfo  to  corrode  the  brafs  of  the  barrel  more,  from  the  acid  imparted 
by  the  bark,  with  which  it  is  tanned ;  it  alfo  emits  a  greater  quantity  of  elaftic  fluid  in  vacuo  than  leather 
which  is  net  tanned.  On  thefe  accounts,  I  have  ufed  buck-ftin  leather  for  the  pifton  ;  but  the  texture  of 
this  being  very  loofe,  oil  only  would  not  fill  its  pores,  fo  as  to  make  the  pifton  air-tight,  even  when  the 
leathers  were  clofely  prefled ;  and  it  was  neceflary  to  fill  its  grain  with  the  above  ftiflfer  compofition.  Yet 
this  leather  will  alfo  generate  air,  and  is  harder  to  be  made  air  faft ;  it  alfo  moves  fo  ftiffly  in  the  barrel,  that, 
perhaps,  good  flioe  leather  is  preferable  to  it.— L. 

banelj 


Defcripiion  of  a  ttev)  Air-pump.  503 

■barrel,  -within  which  cafe  Aides  the  toothed  bar,  or  rack,  F,  moved  by  the  wheel,  and  this  rack 
^(with  its  cafe)  is  fixed  exaftly  parallel  to  the  axis  of  the  cylinder,  that  it  may  draw  out  the 
pifton  rod  precifcly  in  that  direftion  in  which  itfelf  moves :  the  bar  is  -/g  of  an  inch  in 
fhicknefs,  but  is  an  inch  in  breadth  from  the  bottom  of  its  teeth  to  the  back  of  it.  It  is 
?nade  thus  ftrong,  that  the  end  of  it  may  not  be  drained  upward  from  the  proper  diredion, 
when  it  is  urged  forward  by  the  wheel,  and  yet  checked  by  the  pifton  rod,  after  the  pifton 
is  raifed  to  the  top  of  the  barrel.  To  confine  the  rack  in  the  true  line  of  its  motion,  it  is 
made  perfedlly  ftraight,  and  of  the  fame  dimenfions  in  its  whole  length,  and  its  cafe  the 
fame,  fo  as  to  fit  each  other  moft  exactly,  that  it  may  be  kept  in  its  due  pofition,  when  the 
greateft  part  of  it  is  drawn  out  of  the  cafe ;  for  which  purpofe  alfo  it  is  made  (as  likewifc 
the  cafe)  fo  much  longer  at  either  end  than  the  part  neceflary  to  be  toothed,  as  to  permit  a 
great  part  of  it  to  remain  in  the  cafe,  when  the  pifton  rod  is  drawn  out  to  its  utmoft  extent : 
accordingly  in  this  pump  it  ads,  in  this  refpeft,  as  well  as  could  be  wiflied*.  A  notch  is 
cut  out  of  the  cafe  at  I,  to  allow  the  teeth  of  the  wheel  ^o  take  into  thofe  of  the  rack ;  and 
to  keep  the  cafe  firmly  in  its  place,  little  notches  are  cut  in  the  upper  edge  of  it,  into  which 
the  contiguous  parts  of  the  pillars  are  let,  and  it  is  fecured  fo  by  wedges,  2  2,  underneath. 
It  will  be  known  that  the  cafe  of  the  rack  has  its  due  pofition,  when  the  arm  G  being  taken 
off,  both  the  rack  and  the  pifton  rod  pulled  out  to  their  limit,  are  found  to  be  parallel.  The 
pillar^  are  made  as  fliort  as  poflible  j  to  favour  which  the  frame  M  has  a  furrow  cut  in  the  . 
middle  of  it,  under  the  wheel  I,  to  let  the  teeth  of  the  wheel  defcend  almoft  to  the 
table  on  which  the  machine  refts  \  and  the  pump  barrel  is  placed  as  near  as  may  be  to  the 
rack. 

On  the  upper  part  of  the  box,  containing  the  collar  of  leathers,  is  a  projefting  part  of  the 
metal,  in  the  fliape  of  a  cube,  forming  a  little  pedeftal  Qj  on  this  is  placed  the  valve y";  from 
beneath  which  defcends  a  ftraight  duft  into  the  barrel,  without  penetrating  the  box :  the 
form  of  the  parts  of  this  valve  (all  made  of  brafs,  and  of  the  fize  of  the  originals  belonging 
to  the  pump)  is  reprefented  in  fig.  4.  in  a  vertical  fedion.  A  A  is  a  fquare  plate  (to  be  taken 
off  if  it  (hould  require  to  be  ground  and  poliflied  anew  In  contadl  with  the  valve),  which  is 
fattened  on  the  pedeftal  with  cement ;  it  has  a  hole  in  the  middle,  being  the  opening  of  the 
du£l,  in  which  is  inferted  the  little  elevated  pipe  c,  to  be  occafionally  taken  out ;  whofe  ufe 
is  to  prevent  the  oil  applied  to  the  valve  from  being  blown  down  into  the  du£i:  by  the  air  ru(h- 
ing  into  the  barrel :  the  elevated  part  of  the  plate  a,  a,  is  circular,  and  has  its  upper  furface 
made  plane  and  poliflied,  on  which  refts  the  valve  D  j  which  is  fo  far  hollowed  within,  that 
only  its  lower  edge,  being  about  ^^'^th  of  an  inch  thick  (which  is  alfo  well  poliflied),  may  be  in 
contad  with  the  plate  finder  it,  and  alfo  that  its  cavity  may  rife  above  the  little  pipe :  the  valve 

*  By  this  contrivance  of  fixing  the  barrel  of  the  pump  horizontal,  and  its  rack  underneath  the  barrel,  it  is 
made  fo  portable,  that  I  have  packed  it  (the  gage-glafs  and  receiver  being  taken  off)  in  a  box  two  feet  long, 
eighteen  inches  wide,  and  fcven  in  depth  ;  and  it  Ihould  be  remembered  that  the  moft  operofe  parts  of  it  here 
defcribed,  are  the  frame  and  machinery  neceffary  to  render  a  pump,  with  fo  long  a  Cylinder,  portable  ;  a  great 
p3rt  of  which  machinery,  if  it  were  not  portable,  would  not  be  fpared,  but  merely  exchanged  for  the  huge 
fiame  of  tbofe  fo  conftrufted. — L. 

3  T  2      -  is 


5^4  Defmpihn  of  a  new  Air-pump, 

is  almoft  cylindrical,  tapering  but  a  little  from  the  bafe  upward,  and  being  laid  on  tbe  plate, 
■with  a  fmall  drop  of  oil  interpofed,  the  hollow  cylindrical  cap  E,  very  little  wider  internallT 
than  the  valve,  is  put  over  it,  being  faftened  down  on  the  proje£ting  circular  part  of  the  plate 
a  a.  To  let  die  air  pafs  through  this  cap,  three  little  holes,  e,  e,  are  made  in  its  fides,  the 
centres  of  which  are  juft  as  high  as  the  lower  edge  of  the  valve  D,  when  it  is  raifed  to  touch 
tlie  top  of  tlie  cap  ;  the  holes  being  higher  than  the  plate  under  the  valve,  that  the  oil  may 
not  run  out  by  them.  When  this  valve  is  found  to  admit  air  into  the  barrel,  it  is  occa- 
fioned  either  by  the  oil's  being  blown  away,  or  fomc  particle  of  dufl,  &c.  getting  between  it 
and  the  plate  (which  would  produce  the  fame  efFeft  in  any  valve),  and  is  remedied  by  taking 
it  off,  wiping  it  clean,  and  applying  another  drop  of  oil :  the  greater  the  quantity  of  air  is, 
which  paffes  by  the  valve,  the  more  is  the  oil  diffipated ;  and,  confequcntly,  this  chiefly  hap- 
pens in  the  beginning  of  the  exhauftion,  when  much  air  is  drawn  from  the  receiver,  and 
thrown  out  of  the  barrel  at  each  ftroke ;  (b  that  whenever  great  rarefa£Hon  is  requifite,  I 
often  found  it  convenient,  towards  the  end  of  the  operation,  to  apply  a  frefli  drop  of  oil  to  the 
valve,  keeping  the  pifton  in  the  mean  time  elevated  to  the  top  of  the  barrel,  whilft  the  valve  is 
taken  off,  until  It  be  replaced;  which  is  done  in  an  inftant :  thus  it  will  perform  perfectly 
well  if  quite  clean  and  free  from  duft  ;  but  as  the  fmalleft  particle  of  dirt,  or  mucus  (which 
is  apt  to  be  produced  from  the  oil's  corroding  the  brafs,  and  becoming  clammy),  will  render 
die  valve  not  air-tight,  I  am,  therefore,  perfuaded,  that  no  valve  will  fo  perfectly  or  eer« 
tainly  exclude  air  as  a  ftop-cock  ;  and  this  I  take  to  be  the  chief  reafon  why  Mr.  Smeaton's 
pump,  as  improved  by  Meflrs  Haas's  and  Hurter's  contrivance,  for  raifmg  the  valve  at  the 
bottom  of  the  barrel,  does  not,  in  pradtice,  anfwer  as  well  as  any  other :  for  if  fome  air  did 
not  return  into  the  receiver  by  that  valve  in  pumps  on  his  conftru£tion,  it  would  be  hard  to 
tell  why  it  fhould  not  perform  as  well  as  a  pump  of  any  other  conftruQicn. 

To  the  bottom  of  the  barrel  is  faftened  by  four  fcrews,  paffed  through  its  prominent  rim, 
the  circular  plate  R,  forming  In  pari  the  fliell  of  the  cock  S,  and  which  has  the  high  ridge 
T  on  the  back  of  it ;  all  thefe  being  only  one  piece  of  metal,  which  is  reprefented  fepa- 
rately  in  fig.  5-.  and  was  caft  in  that  form  :  the  round  plate  is  about  Jth  of  an  incH 
thick ;  but  the  cavity  of  the  cock  intrudes  fo  far  on  this,  that  when  the  key  of  the 
cock  is  put  in,,  the  thicknefs  of  the  plate  in  the  part  direftly  over  the  key,  where  the 
dufts  open  into  the  barrel,  is  not  more  than  ith  of  an  inch:  the  length  of  the  ftieii 
of  the  cock  is,  three  inches;  that  of  the  key  -Jth  of  an  inch  lefs :  the  diameter  of  the 
key,  at  the  thicker  extremity  is  i  to^is  of  an  inch,  and  at  the  fmaller  end  i  ;|th  of  an 
inch.  It:  is  turned  by  the  handle  u,  faftened  on  its  axis  as  near  to  the  end  of  the  fhell 
as  may  be;  viz.  at  the  diftance  of  l^h.  of  an  inch.  Care  was  taken  that  the  metal  of  the 
cock  fhould  be  free  from  pores,  by  which,  if  air  were  admitted  in  the  working,  it  would  be 
very  hard  to  difcover  it,  as  this  might  take  place  only  in  certain  pofitious  of  the  key ;  and  the. 
ointment  might  fometimes  prevent  and  fometimes  fuffer  it,  fo  that  it  might  elude  trials  ; . 
the  cock  was  alfo  fo  truly  and  fmoothly  ground,  as  to  produce  an  intimate  contaft  of  the' 
key  and  ftiell . throughout  (for  air  will  penetrate  where  liquids  would  not);  it  was  alfo' 
jnade  of  a  true  conical  fliape,  its  fides  being  perfectly  ftraight  from  end  to  end.    The  cock' 

muii 


I 


m 


Deferiptm  if  a  new  Atr-pump',  $o^ 

muft  be  lubricated,  and  made  air-tight  by  ointment  * ;  and  as  all  oil  or  greafy  ointment  ha». 
an  acid  in  jt  (of  which,  perhaps,  it  can  never  be  divefted  without  deftroying  its  lubricity) 
which  corrodes  the  brafs,  and  ftifFens  the  oil  or  ointment  itfelf,  by  impregnating  it  with 
green  ruft  or  verdegris,  I  found  it  neceff"ary>.  after  the  cock  was  finifhed>  to  have  the  key. 
and  the  infide  of  the  (hell  eoated  with  tin. 

The  key  of  the  cock  terminates  in  a  littk  knob  k,  fig.  2.  againft  which  the  end  of  the 
tliin  fpring  lever  y  prefles  to  keep  the  key  conftantly  firm  in  its  fhcU :  this  fpring  is  made 
to  urge  onward  the  key,  with  any  degree  of  force  requlfite,  by  the  fcrew  at  y,  fcrewcd 
through  the  outer  part  of  the  little  arch,  or  frame,  which  frame  is  itfelf  faftened  by  fcrews 
on  the  prominent  ring  of  the  barrel,  as  appears  at  z,  fig.  2.  The  lever  has  a  little  ridge, 
or  elevated  part,  which  refts  in  a  notch  in  the  frame ;  by  which  the  lever  is  fixed  in  its 
proper  place,  the  notch  being  the  fulcrum  :  by  withdrawing  the  fcrew  the  ridge  may  be 
raifed  out  of  the  notch,  and  the  lever  pulled  back  from  the  knob,  to  let  the  key  be  taken  out 
when  it  requires  more  ointment ;  which  will  be  known  when  it  has  worked  into  the  fliell 
nearly  to  its  limit ;  and  this  fliould  be  carefully  learned,  by  marking  how  far  it  can  be  in— 
ferted  into  the  (liell  without  any  ointment  intcrpofed.  The  form  of  the  key,  and  its  lever, 
is  exhibited  in  fig.  6.  in  an  horizontal  fedlion  through  the  middle  of  them; 

Through  the  fliell  of  this  cock  are  two  round  perforations  for  two  dufts,  through  the; 
cock,  each  one  inch  diftant  from  the  other,  and  the  fame  from  the  end  of  the  cock  on  either- 
fide  :  they  are  in  a  plane^  or  fe£tion,  paffing  through  the  axis  of  the  key,  and  alfo  through 
the  axis-  of  the  barrel ;  and  bothpafs  through  the  ridge  of  metal  T  at  the  back  of  the  fliell. 
The  du£t  irext  the  fmaller  end  of  the  key  (being  a  part  of  the  du£l  communicating  with  the 
receiver)  is  in  diameter  :^th,  and  the  other  dufl:  is  only  ^th  of  an  inch :  through  the  key,  alfo^ 
are  du£ts  aniwcring  to  the  perforations  in  the  (hell ;  but  the  du£ts  in  the  key  are  not  both' 
in  the  fame  fedion  of  it,  but  oneef  them  is  at  right  angles  to  the  other ;  fb  that  whsn  one- 
of  the  dufts  through  the  cock  is  open,  the  other  will  be  always  fiiut,  and  vice  verjd. 

There  is  a  continuation  of  each  of  thofe  da£Vs  formed  in  the  piece  of  metal  V,  which  i* 
joined  (by  cement  interpofed)  to  the  ridge  of  the  fliell. of  the  cock  by  the  four  fcrews  g,  gt 
fig.  I.  by  two  openings  (into  the  two  dufts  in  the  piece  of  metal)  oppofite  to  thofe  in  the. 
ridge  ;  and  thefe  dufls  in  the  piece  V  have  two  other  orifices  at  a,  and  r,  where  the  two- 
pipes- a  i,  fig  I.  and  c  d^  fig.  2-  communicate  with  the  two  canals  in  the  piece  of  metal, 
being  conneded  with  them  only  by  the  help  of  cement,  that  the  barrel  with  its  cock  may  be 
occafionaliy  disjoined  from  them :  thus-  a  feparate  ccmimunication  is  formed  between  each' 
of  the  pipes,  and  the  barrel. 

The  pipe  a  b  isonly  rVth  of  an^inch  in  diameter,  except  at  its  orifices,  which  are  widened; 

'■*  This  I  have-  made  of  one  part  of  common  rofin,  one  part  oil,  and  one  part  and  a  half  frefh  fuct :  the  oil. 
and  rofin  is  firft  melted,  and  when  a  little  cooled  the  fuet  is  added,  that  the  heat  requifue  to  melt  the  rofia 
may  not  burn  the  fibrous  part  of  the  fuet,  and  dearoy  its  firmnefs  :  more  oil  is  to  be  added  in  cold,  than  in 
warm  weather.  The  quality  of  the  ointment  for  thecock  is  of  the  utmoft  confequence  ;  for  if  ever  the  parts 
of  the  metal  of  the  cock  came  into  immediate  contaa,  it  will  not  be  air-faft-  oil  will  not  render  it  fo  (not 
wnfequently  would  a  valve) ;  but  the  ointment  muft  be  ftiff  and  adhefive  ;  yet  not  too  ftiff,  as  then  k  would  ■ 
bf  hard  to  turn  the  key,  and  it  could  not  be  diftinguiflied  whether  its  ftiffneft  was  owing  to  the  ointment,. or. 
to  theiriaion  o£  the  parts  of  the  metal  getting  into  iromediau  contad,  wliich  would  be  pernicious.— L. 

onej 


ro6  Defcriptioii  of  a  nnu  Air-pump, 

one  of  them  is  connected  at  b,  with  a  duft  formed  in  the  piece  of  metal  k,  attached  to  the 
box  of  leathers  C  at  the  top  of  the  barrel,  which  dud  turning  in  an  angkj  without  pene- 
trating the  box,  opens  into  the  barrel :  this  pipe  and  duft  are  joined  by  a  fimple  application 
of  their  orifices,  which  are  made  in  the  contiguous  fides  of  both,  and  the  joint  made  air- 
tight, by  cement  melted  around  with  a  blow-pipe ;  and  the  fame  might  be  eflefted  by  the 
prefiure  of  a  fcrew  clofmg  the  furfaces  with  oiled  leather  Interpofcd.  By  this  pipe  when 
■  the  valve  is  fhut,  and  tlie  key  of  the  cock  fo  placed  that  the  communication  of  this  pipe 
with  the  bottom  of  the  barrel  is  open,  if  the  pifton  be  deprefled  from  the  top,  all  the  air 
which  is  under  it  will  be  forced  to  pafs  by  this  pipe  into  the  barrel  above  the  pifton  ;  and 
•vice  verfd  if  the  pifton  be  elevated  from  the  bottom ;  fo  that  according  to  the  motion  of  the 
pifton,  the  air  under,  or  over  it,  within  the  barrel,  is  made  to  change  its  place,  and  to  cir- 
culate from  the  fpace  under  or  above  the  pifton  to  the  contrary ;  from  which  effect  of  this 
pripe,  I  call  it  the  circulating  pipe. 

.  The  other  pipe,  or  duft,  is  reprefented  at  c  d,  £g.  2.  which  exhibits  a  back  view  of  the 
pump  :  its  extremity  c  enters  the  block  of  metal  V  to  communicate  with  the  dudl  therein, 
^ad  fo  with  that  through  the  cock  into  the  barrel :  its  end  c  has  a  wing  foldered  to  it,  by 
which  it  is  firmly  fcrewed  to  the  piece  V;  this  being  neceflary  left  the  cement  by  which 
alone  the  joint  there  is  made  air-faft,  fliould  be  cracked  by  any  (hock  moving  the  barrel ; 
or  it  might,  perhaps,  be  fecured  by  the  fcrew  with  only  leather  interpofed  :  this  du£l:  is  a  very 
■Vpide  one,  that  the  air  may  the  fooner  pafs  through  it ;  it  has  a  turn  at  right  angles  at  d, 
'^d  another  at  e,  from  whence  it  extends  under  the  pillar  B,  and  pump-plate  C  D,  through" 
the  middle  of  which  it  rifes  at  A ;  it  has  a  branch  turning  at  right  angles  from  A  under  the 
pump-plate,  the  end  of  which  terminates  in  a  round  orifice  with  an  infide  fcrew,  that  by 
means  of  a  pipe  furnifhed  with  a  ftop-cock  ;  or  otherwife  another  pump-plate  and  receiver, 
Qr  feveral  of  them,  may  be  connected  with  it,  being  laid  on  the  fame  table  which  fupports 
tlic  pump :  when  fuch  are  not  ufed,  the  orifice  is  clofed  with  a  ftop-fcrew  as  at  D.  From 
tliis  pipe  rifes  a  branch  E,  inferted  into  the  top  of  the  brafs  cap  F  of  the  glafs  veflcl  Y,  and 
opening  into  the  veflel  by  a  duft  made  in  the  thick  plate  of  the  cap.  G  is  a  reduced  baro- 
meter tube,  to  be  filled  in  the  moft  perfeft  manner  with  mercury,  and  immerfed  into  a  pool 
of  mercury  in  the  bottom  of  the  glafs  vefTel.  The  interval  between  the  tube  and  the 
neck  of  the  veflel  is  clofed  by  cement,  which,  as  the  neck  muft  be  a  good  deal  wider 
than  the  tube,  is  efi^e£ted  by  a  deep  ring  (I)  fitted  to  the  tube,  having  a  round  plate  at  the 
bottom  of  it ;  which  being  let  down  on  the  tube  after  it  has  been  immerfed  in  the  ciftern,« 
is  joined  with  cement  to  the  top  of  the  cap.  The  tube  was  eafily  immerged  in  the  mercury 
within  the  veflcl,  by  covering  its  open  end,  and  fuftaining  the  mercury  in  it  by  a  little  plate, 
or  fcale  of  iron  (P),  fig.  7.  having  two  threads  tied  to  it,  through  two  holes  made  near  its 
edges  ;  which  threads  were  grafped  together  with  the  top  of  the  tube  between  the  fingers, 
and  the  tube  was  inverted,  and  let  down  into  the  mercury  in  the  veflel :  the  little  plate  was 
then  pulled  up  by  one  of  the  threads,  it  being  made  fo  fmall  as  to  pafs  through  the  neck 
of  the  glafs  while  the  tube  was  within  it,  and  remained  immerfed  in  the  mercury* :  the 
•  I  thought  this  the  beft  way  of  fixing;  the  reduced  barometer,  for  if  there  were  a  feparate  veffel  as  a 
ciftern  for  the  raercury,  and  a  receiver  placed  over  it  and  the  tube,  the  eye  when  on  a  level  with  the  furface 
of  the  ttagnam  mercury,  could  not  fee  the  altitude  of  that  in  the  tube  with  prccifion  through  two  glaffes.— L. 

veflcl 


Defcriptim  of  a  nenv  Air-pump.  507 

TCffel  was  then  clofed  at  the  top  with  melted  cement ;  and  as  It  communicates  by  the  pipe 
E  with  the  cortduit-pipe,  it  is  exhaufted  with  the  receiver,  and  the  mercury  in  the  tube  will 
fink- as  the  rarefaction  advances :  if  a  perfedl  vacuum  could  be  made  in  the  receiver,  and 
gage-veflel,  it  would  fmk  more  or  lefs  beneath  die  level  of  the  furrounding  mercury,  as 
the  tube  is  narrower  or  wider,  even  fo  as  to  difappear  if  the  tube  were  very  narrow  ; 
fo  that  it  muft  not  be  lefs  than  Ti,ths  of  an  inch  in  diameter  j  but  it  would  be  better 
if  it  were  -rstlis.  If  it  were  obferved,  how  much  the  mercury  in  a  tube  open  at  both 
ends  would  fink  beneath  the  level  of  that  in  a  ciftern  in  the  open  air,  it  might  be  pretty 
nearly  eftimated  how  great  is  the  rarefaftion  in  this  gage-veflel,  and  confequently  in 
the  receiver*. 

In  order  that  each  of  tlie  dufts  here  defcribed  fliould  alternately  communicate  to  tlie  bar- 
Tel,  it  is  neceflary,  that  the  cock  fliould  be  moveable  through  a  quarter  of  a  turn,  and  confined 
to  that  motion.  This  is  efFe£ted,  by  a  pin, «,  fixed  perpendicularly  in  the  back  of  the  handle, 
fig.  I .  which,  when  the  handle  is  fixed  in  its  place,  defcribes  a  quadrantal  arc,  imder  the  ftiell 
of  the  cock,  where  there  is  jufl  room  to  allow  fuch  a  motion. 

The  aftion  of  this  pump  may  be  readily  apprehended  from  the  conftruftion  of  its  parts. 
When  the  pifton  is  at  the  bottom  of  the  barrel,  and  the  key  of  the  cock  turned  to  its  limit 
which  opens  the  communication,  between  the  barrel  and  the  receiver  and  at  the  fame  time 
fhuts  that  with  the  circubting  pipe  •,  the  pifton  being  then  drawn  to  the  top  of  the  barrel  dif- 
charges  the  air  through  the  valve,  while  other  air  from  the  receiver  ruflies  into  the  barrel,  and- 
follows  the  pifton.  As  foon  as  the  pifton  has  arrived  at  the  upper,  or  more  remote  end  of  the 
barrel,  the  key  of  the  cock  is  again  turned,  and  fliuts  off  the  connexion  with  the  receiver,  and 
opens  that  with  the  circulating  pipe.  The  pifton  being  then  depreffed,  drives  the  air  through 
the  pipe,  into  the  upper,  or  remote  end  of  the  barrel.  When  the  pifton  has  arrived  at  its 
limit,  the  fljoke  is  ended,  the  key  of  the  cock  is  to  be  again  turned  to  open  the  receiver,  and 
a  fecond  ftroke  may  be  made,  with  the  feme  confequences  as  the  firft ;  and  in  this  manner  the 
procefs  may  be  continued  at  pleafure.  The  limit  of  exhauftion  will  be  when  the  air  in  the 
receiver  fliall  have  become  as  rare  as  the  air  in  the  barrel  would  be  when  the  pifton  is  up; 
fuppofing  no  communication  to  have  taken  place  between  it  and  the  receiver. 

When  the  pump  is  required  to  condenfe,  the  air  is  made  to  move  in  a  reverfe  direftionJ 
The  cock  of  the  gage-veflel  is  flopped,  that  it  may  not  be  burft ;  the  valve  is  taken  off";  the 
communication  of  the  bottom  of  the  barrel,  to  the  circulating  pipe,  opened  by  tlie  key  of  the 
cock,  and  the  pifton  raifed  to  the  top.  The  external  air  pafles  into  the  lower  part  of  the 
barrel;  and  by  turning  the  cock,  fo  as  to  open  the  receiver,  and  fliut  the  circulating  pipe,  and 
then  deprefllng  the  pifton,  the  air  is  forced  into  the  receiver,  wliich  ought  of  courfe  to  be  of 
fufiicient  ftrength,  and  properly  fccured.  By  fliutting  the  receiver,  raifing  the  pifton,  opening 
the  receiver  again,  and  returning  the  pifton  to  its  former  fituation,  another  ftroke  is  made,  and 
thefe  alternations  may  be  carried  on  to  any  deCred  or  praftlcablc  extent. 

•  The  author  prefers  the  ftiort  barometer-gage  to  the  fyphon-gage,  beeaufe  in  this  !aft  he  thinkt  the 
motion  IS  impeded  by  the  tube,  and  tbe  mercury  becomes  foul  on  that  fide  which  communicates  with 

the  receiver N. 

The 


-j;68  Native  Pi-ujfian  Blue. — Native  Copper. 

■  The  remainder  of  Mr.  Little's  paper,  confifts  of  numerous  obfervations  and  remarks,  with 
feme  experiments ;  a  confiderable  number  of  the  former  of  which  arc  familiar  to  fuch  as 
have  attended  to  this  branch  of  natural  philofophy  :  but  the  whole,  though  evidently  fhort  of 
what  the  author  muft  have  originally  intended,  will  be  read  with  inter^ft  and  fatisfadlion,  by 
thofe  who  may  confult  the  memoir  itfelf. 

-a 
X, 

OVfervaiions  on  Chem'ijiry  and  Natural Hijlory.     By  PjlOF£SSOJl  VaNDELLI*. 
I .  Fojil  Prujfian  Blue  from  Mitias  Geraes  in  the  Brazils. 

An  digging  a  mine  at  S.  loao  del  Rey,  to  the  depth  of  more  than  forty  palms  (about  27  (cet 
Englilh),  large  brittle  bones,  and  fome  teeth  of  a  cetaceous  animal  were  found  in  the  clay, 
which  occupied  a  fpace  of  more  than  fifty  palms  fquare  (about  35  feet  Englifh).  Thefe  bones, 
and  the  clay  with  which  they  were  intermixed,  were  white  when  firft  extraded,  but  foon 
became  blue  when  expofed  to  the  air  f. 

Thefe.bones  and  clay,  in  the  blue  (late,  being  expofed  to  the  aftion  of  a  moderate  fire,  be- 
came green,  emitted  a  weak  flame,  and  afterwards  loft  their  colour.  The  reddifh  earth  which 
remained  was,  for  the  moftpart,  attraftedby  the  magnet. 

The  Pruffian  blue  was  foluble  inthe  marine  acid,  and  in  this  ftate  loft  its  colour.  By  addi- 
tion of  a  fixed  alkali,  the  precipitate  was  afforded  of  a  green  colour,  which  afterwards  became 
blue,  of  more  intenfity  then  at  firft. 

.  The  mixture  of  bones  and  clay,  being  fufed  with  a  proper  flux  for  iron,  afforded  three 
parts  of  their  weight  of  iron,  which  was  intirely  attraded  by  the  magnet. 

Refpeding  the  fofTil  Pruffian  blue,  as  the  reader  may  confult  the  works  of  Wallerius,  Berg- 
man and  Kirwan,  I  fhaH  not  enter  into  any  further  detail. 

.2.  Native  .Cupper  of  Brazil.  This  mafs  of  copper  was  found  in  a  valley  two  leagues 
from  Cachoeira,  and  fourteen  from  Bahia.  It  weighs  nearly  2616  arratels  (or  nearly  pounds 
Englifh),  and  its  figure  is  rhomboidal,  the  upper  furface  being  irregular,  on  account  of  fomc 
cavities  and  protuberances.  Its  greateft  height  is  three  feet  two  inches,  its  width,  at  the  bafe, 
two  feet  and  a  half,  and  its  greateft  thicknefs  ten  inches,  Paris  meafure  %. 

The  external  colour  of  the  mafs  is  deep  reddifh,  with  fpots  and  particles  of  a  greenifh  blue, 
produced  by  the  decompofition  of  the  copper.  On  the  lower  furface  appear  fome  yellow 
fpots  of  ochre  of  iron. 

At  various  parts  of  the  furface,  particularly  the  lower  furface,  feveral  pieces,  large  and 
fmall,  are  obferved,  which,  at  firft,  feem  to  hzferrum  micaceum ;  but  when  examined  by  fire 
they  prove  to  be  indurated  oxide  of  copper.  For  an  ounce  of  this  fubftance  afforded 
thirteen  parts  out  of  fixteen  pure  copper. 

*  From  the  Tranfaftions  of  the  Royal  Academy  of  Sciences  at  LiHon,  I.  259. 
if  For  an  explanation  of  this  phenomenon,  fee  Prouft  in  this  Journal,  I.  455. 
J  The  foot-royal  ofParis  is  to  that  of  London  a»j,Qooo  to  0,9383. — l^L 

Tlug 


Manujaclure  efUaUy  Cj'c-.  joj^ 

Tkis  copper  being  afiayed,  afforded  no  indications  of  gold  or  filvep. 

Another  piece  of  virgin  copper  was  found  at  the  fame  place,  but  much  fmaller  than  the 
{orcgoing.  A  mafs  of  copper,  of  the  magnitude  here  dcfcribed,  has  very  rarely  beea  met 
with,  as  Mr.  Monnet  remarks*. 

XL 

On  the  MtuiufaBure  of  Hats,  and  other  OhjeEls.     By  a  Correfpondent. 

ToMr.-NICHOLSON. 

SIR,  Newcaftle,  9th  January,  i75f. 

H  E  obliging  manner  in  which  you  have  noticed  my  enquiries,  refpe£i:ing  the  hatting 
bufinefs,  induce  me  to  fend  you  others  on  another  bufinefs,  equally  productive  of  mifchief, 
to  the  morals  and  the  health  of  a  clafs  of  induftrious,  but  depraved,  fellow  men — I  mean  the 
journeymen  flax-dreflers  j  thofe  and  the  journeymen  hat-makers,  are  almoft  proverbially 
vicious,  and  I  confefs  I  look  with  fangulne  expe£lations  of  reform,  to  the  period  that  will 
exhibit  machinery  for  each. 

Is  it  poffible  to  conftruft  a  machine,  for  the  purpofe  of  drefling  flax?  There  are  machines, 
I  underftand,  in  Scotland,  invented  about  40  years  ago  (vide  Englilh  Encyclopedia,  article 
Flax  Dreffmg),  for  the  breaking  and  fcutching  of  that  article :  might  thefe  not  be  extended  to 
the  further  procefs  of  the  heckles  ?  Perhaps  the  claim  is  equally  upon  humanity  as  ingenuity, 
for  I  have  been  told  (and  I  have,  from  my  own  knowledge  in  that  bufinefs,  fcarce  any  doubt 
of  its  truth),  that  the  journeymen  are  obliged  to  give  it  over,  about  the  age  of  40,  from  an  ap. 
proach  oi  conjumptwn  ^  and  one,  whom  I  am  told  was  lately  opened  at  his  death,  had  his  lungs 
covered  with  a  thick  crujl,  compofed  of  the  dirt  received  upon  them  from  his  bufinefs. 

Accept  the  following  information,  as  the  beft  I  can  yet  afford  you,  on  the  fubje£l  of  my 
queries  in  your  laft  (p.  467) ;  they  have  been  obtained  fince  my  writing  to  you  (on  the  fub- 
je£l.  Hats  were  invented  at  Paris,  A.D.  1404,  by  what  circumftance  I  am  yet  ignorant. 
Firft  made  in  London,  1 5 10.  The  above,  though  an  anonymous  communication  ,to  me,  I  be- 
lieve will  not  be  found  far  from  the  truth.  There  is  a  houfe  in  Derbylhire,  name  Cooper  Bibby 
and  Downal,  at  Lea  Wood,  near  Cromford,  in  that  county,  who,  I  underftand,  ufe  machines 
in  the  making  of  hats,  but  how  far  in  the  procefs  I  am  not  yet  able  to  difcover:  perhaps 
fome  of  your  correfpondents  may  have  informed  you,  in  confequence  of  my  queries.  The 
common  accoimt  amongft  the  journeymen  is,  that  the  property  of  wool  to  felt  was  firft  difcovcred 
by  a  (hepherd,  who  had  wool  in  his  ftioes;  his  name  was  Clement,  and  they  keep  the  25th  of 
November,  as  a  A'iyj  facred  to  dffipation  and  an  old  fhepherd  faint.  Saint  Catherine,  I  under- 
ftand, is  the  patronefs  of  the  journeymen  flax-dreffers.  It  is  probable,  they  will  celebrate  the 
25th  of  November. 

*  Nouveau  Syftcme  ae  Mineralogie,  page  314,  Mines  de  Cuivrc.  The  Cabinet  of  Mines  at  Frcyberg'pof- 
feflcs  a  fpecimen  of  this  kind,  weighing  ten  pounds,  which  is  the  fineft  and  largeft  fpecimen  of  native  copper 
hitherto  known. 

Vol.  II.— Feb.  1799.  3U  Thefe 


5 1 0  Excurjtons  to  MonUPerdu. 

Thefe  fuggeft'ions  may,  I  hope,  afford  a  thread  to  others,  more  converfant  in  the  theory  of 
Mahuzzim,  or  faints  proteftors,  than  I  am,  to  favour  you  with  information  of  more  confe- 
quence  on  the  fubje£ls  of  the  manufactories  in  queftion.  The  editors  of  the  EngHfli  Ency- 
clopedia fay,  that,  on  the  fubjeft  of  dreffing  flax,  they  refer  their  readers  to  fome  obfervations 
in  the  Gentleman's  Magazine,  for  June,  1787  :  I  have  not  that  book  at  hand,  but  I  hope 
your  readers  may  find  in  it  fome  ground-vi'ork  for  future  machinery. 

I  am,  fir. 

Yours,  &c. 

N.L. 
In  the  liquor  for  boiling  of  wool  hats,  after  bowing  and  bafoning,  one  part  of  human  urine 
IS  made  ufe  of,  and  two  parts  clean  foft  water  :  Could  not  fomething  be  fubftituted  in  place  of 
the  urine,  which  might  be  equally  ufefttl  w  hardening  the  hoad^  and  exclude  fo  dirty  an  ingre- 
dient*? 


XII. 

ExtraB  of  a  Letter  from  Citizen  Ramond,  AJfodate  of  the  National  Inflitiite  of  France ,  and  Pro- 
fepr  of  Natural  Hiflory  at  Tarbes,  to  Citiztn  Haiiy,  Member  of  the  InfituU  at  Paris,  refpeB- 
ing  two  excuifions  to  Mount  Perdu,  the  mofl  elevated  fummit  of  the  Pyrenean  Mountains*. 


I 


Bareges,  5  eomplera.  day,  in  the  year  V. 


FLATTER  myfelf,  Citizen,  that  you  will  not  hear,  without  intereft,  fuch  events  as  have 
proved  mofl;  remarkable  in  the  refults  of  my  travels  of  the  prefent  year.  I  haften  to  com- 
municate them,  with  the  hope  that  the  portion  of  your  time  which  I  fliall  engage  will  be  well 
repaid  by  the  geological  fail  which  is  the  obje£t  of  this  letter. 

Mount  Perdu  is  the  mofl:  elevated  mountain  in  the  chain  of  the  Pyreneans.  In  my  for- 
mer travels,  I  proceeded  along  the  bafes.  Reboul,  who  has  fucceeded  in  determining  its 
height  by  obfer\'ations  made  from  various  elevated  points,  had  likewife  approached  it  in  a  dif- 
ferent direftion.  It  is  certain  that  the  whole  of  the  furrounding  group  is  calcareous,  and 
the  afpeft,  which  can  fcarcely  deceive  thofe  who  are  habituated  to  behold  and  contemplate 
mountains,  had  determined  my  belief  that  the  entire  pic  was  of  the  fame  nature. 

Abundance  of  calcareous  matter  forms  one  of  the  diftindt  chara£lers  of  the  Pyrenean 
mountains ;  but  to  behold  this  genus  in  poffeflion  of  the  very  creft  of  the  chain,  the  place 
which  the  granite  occupies  in  every  other  known  chain  of  mountains,  was  a  phenomenon  tod 
fingular  not  to  infpire  me  with  the  ftrongeft;  defire  to  afcertain  its  exiftencc. 

The  enterprize  was  not  without  its  difficulties ;  and  among  them,  that  which  was  the  leafl 

*  The  preparations  for  my  change  of  refidenee,  as  mentioned  en  the  wrapper,  have  induced  me  to  defer  my 
own  obfervations  and  report,  concerning  hatting,  till  next  month. — N. 

f  Read  to  the  French  National  Inftitute  at  the  fitting  of  the  2 1  ft  Vendemiaire,  in  the  6th  year  of  the  Repub- 
lic (12th  Oftober,  i797)»  and  inferted  in  the  Jour»al  de  Mines,  No.  37,  of  the  fame  ye^r. 

forefce% 


Calcareous  Summit  of  the  Pyrenean  Mountains.  51 X 

forefeen,  was  the  abfolute  ignorance  in  which  I  found  all  the  country  people,  with  regard  to 
the  real  pofition  of  Mount  Perdu.  It  is  not  vifible,  but  from  the  elevated  fituations,  and  dif- 
appears  as  foon  as  you  defcend.  It  was  neceflary,  therefore,  to  feek  the  road,  as  chance  might 
direft,  through  the  moft  horrid  deferts,  which  are  never  frequented,  either  by  the  hunter,  or 
by  ftiepherds. 

On  this  occafion,  I  had  the  good  fortune  to  enjoy  the  company  of  our  colleague.  La  Pcy- 
roufe ;  and  I  ufed  every  effort  in  my  power  to  fecure  his  company  in  thofe  regions,  in  which 
I  forefaw  fo  many  interefting  obfervations  would  prefent  themfelves.  But  his  ftrength  did 
not  permit  him  to  accompany  me  longer  than  the  firft  day,  and  part  of  the  fecond.  I  left 
him  at  the  foot  of  the  firft  glaciere,  taking  with  me  his  fon,  and  one  of  his  pupils,  togetlier 
with  four  of  my  own.  I  will  not  fatigue  you  with  the  detail  of  our  own  fufFerings,  nor 
alarm  you  with  an  account  of  our  dangers ;  but  fliall  fimply  obferve,  that  after  having  Im- 
printed our  fteps,  during  three  hours,  in  the  hardened  fnows,  which  the  inclination  of  their 
plane  rendered  very  dangerous,  we  arrived  at  a  fummit  oppofite  Mount  Perdu,  which  raifed 
U3  to  its  middle  part.  I  never  beheld,  even  in  the  Alps,  any  objeft  of  greater  magnificence : 
I  do  not  except  the  approaches  to  Mount  Blanc.  The  calcareous  mountains  poflefs  a  fim- 
plicity  of  form  and  majefty  which  is  peculiar  to  them :  now  Mount  Perdu  is  calcareous,  ab- 
Iblutely  calcareous,  and  of  fecondary  compoCtlon.  I  defcended  from  my  fituation  towards  a 
vaft  lake,  ftill  frozen,  which  repofes  at  its  feet.  I  crofled  this  lake ;  I  vifited  every  fpot  where 
the  external  fnows,  and  horrid  glacieres,  have  fufFered  the  naked  rocks  to  penetrate..  Every 
where  I  found  grit,  breccia,  and  compacl  calcareous  ftone,  covered  with  the  prints  and  re- 
mains of  marine  bodies :  marine  remains  at  the  fummit  of  the  Pyrenees,  and  on  the  pic 
which  predominates  over  all  thefe  mountains ! — ^This  phenomenon  acquires  a  charafter  ftill 
more  wonderful,  when  we  confider  that  the  entire  chain  exhibits  none  of  thofe  atteftations 
of  the  former  refidence  of  the  ocean ;  and  that  it  is  in  vain  we  feek  them  in  our  fecondary 
calcareous  ftones,  our  bituminous  ftones,  or  flates,  all  which  are  deprived  of  the  prints  of 
fhells  and  vegetables.  I  paffed  from  the  flanks  of  Mount  Perdu  into  the  valley  of  Pinede, 
where  it  pours  its  waters ;  I  came  to  the  port  or  paflage  of  Pinede,  one  of  the  moft  elevated 
■  of  the  Pyrenees.  The  fame  phenomena  every  where  prefented  themfelves ;  every  where  I 
faw  grit,  breccia,  and  common  calcareous  ftones,  abounding  with  marine  bodies ;  and  by  caft- 
ing  my  eyes  along  the  extenfive  valley  of  Pinede,  I  faw,  in  all  parts,  the  continuation  of  the 
banks  in  which  I  had  obferved  thefe  remains. 

La  Peyroufe  had  feen  the  oppofite  fide  of  the  mountains  which  I  vifited  :  he  coafted  along 
them  to  meet  me  at  the  port  of  Pinede.  He  obferved  part  of  thefe  v/onders,  and  partook 
of  my  harveft.  Stormy  clouds  having  covered  the  pic,  at  the  time  of  my  arrival  at  my  firft 
excurfion,  it  became  neceflary  to  revifit  it  at  a  more  favourable  feafon  5  I,  therefore,  refumed 
the  route  of  Mount  Perdu,  fifteen  days  ago,  with  a  couple  of  friends  only,  and  fome  hardy 
mountaineers.  All  the  glacieres  were  then  uncovered,  by  the  diflbhition  of  the  fnow  which 
had  laid  upon  them ;  the  lake  was  unfrozen,  and  the  dangers  of  approach  were  confider- 
ably  increafed.  It  was  neceflary  to  fecure  our  footfteps  in  the  hardeft  ice  by  heavy  ftrokes 
of  the  hatchet.  We  fufFered  much  in  this  excurfion,  and  I  could  not  reach  the  fummit  j 
but  the  flcy  was  admirably  ferene,  and  I  touched,  as  it  were,  thofe  rocks  which  I  could  not 

3  U  2  afcend. 


512  Summit  of  the  Pyrenees. — Fo^I  Bwet, 

afccnd.  At  this  time,  I  beheld  the  whole  ftrufture  of  the  mountains,  the  direftlon  and  in- 
clination of  the  ftrata,  the  entire  fucceffion  of  its  layers ;  every  faft  was  manifeftcd  to  my 
fight,  and  I  completed  my  coUc£i:ion  of  marine  bodies,  which  are  contained  in  thefe  moun- 
tains. 

To  the  weft,  as  well  as  to  the  eaft,  every  part  is  fecondary,  and  full  of  fhellsi  I  fent  one 
of  my  pupils  towards  Vignamale,  who  brought  me  a  comu  ammonis.  It  is,  as  I  have  ven- 
tured to  affirm  in  my  printed  obfervations,  an  enormous  fecondary  mafs,  fuperpofited  on  the 
edifice  of  the  chain,  and  which  covers  the  fouthem  part  to  the  thicknefs  of  ten  or  twelve 
kilometres,  and  is  in  length,  forty. 

The  moft  perfeft  among  the  remains  of  marine  bodies  which  I  found  in  thefe  regions 
is  a  perfeft  ammonite,  the  exaft  impreffion  of  a  pedlinite,  the  prints  of  arterites,  many 
oyfters  in  the  folid,  caryophillites,  and  a  multitude  of  madrepores.  I  fhall  not  enter 
into  more  circumftantial  details.  The  geologic  and  geographic  refults ;  the  nature  and  in- 
clination of  the  different  banks ;  their  connexion  with  the  rocks  which  fupport  them ;  the 
ftate  of  vegetation ;  the  infefts  obferved  in  thefe  elevated  regions ; — will  form  materials  for 
a  memoir,  which  I  intend  to  draw  up,  when  in  a  lefs  interrupted  ftate,  for  the  purpofe  of 
tranfmitting  it  to  the  National  Inftitute.  But  I  am  defirous  that  the  principal  fafts  Ihoald 
be  communicated  to  that  body,  with  all  the  intereft  of  novelty,  and  I  think  them  fufficiently 
interefting  to  requeft  your  mediation  in  this  refpeft. 

If  you  think  it  proper  likewife  to  tranfmit  them  to  the  Council  of  Mines,  I  requeft  that 
you  will  permit  me  to  give  you  the  trouble  of  performing  this  office. 


XIII. 
An  AhflraEt  of  a  Memoir  upon  the  Foffil  Bones  of  Animals.     By  Citizen  CuFIER.  * 

HE  intention  of  the  Author,  in  this  memoir,  was  to  colleft  as  much  as  it  was  in  his  power 
all  the  foflll  bones  appertaining  to  each  fpecies  of  animal,  whether  of  fuch  as  he  himfelf 
had  feen,  or  thofe  of  which  he  merely  had  a  defcription  in  authors,  to  form  or  recompofe 
the  flceletons  of  thefe  fpecies,  and  to  compare  them  with  thof:  which  now  exift  on  the  fur- 
face  of  the  globe,  in  order  to  determine  their  relation  and  differences.  The  following  is  a 
feries  of  the  fpecies  to  which  his  attention  has  been  direfted. 

1.  The  animal  which  afforded  the  bones  and  teeth,  called  the  bones  and  horns  of  the  mam- 
mouth,  by  the  Ruffians,  and  inhabitants  of  Siberia.  Similar  foffile  remains  are  alfo  found 
in  Europe.  It  is  a  fpecies  of  elephant,  refembling  the  elephant  of  Afia ;  but  from  which  it 
differs  in  the  alveola  of  its  teeth,  and  its  tufks  being  longer,  the  angle  of  its  lower  jaw 

•  Communicated  to  the  Societe  d'Hiftoire  Katurelle  at  Pari$.      This  abridgment  is  tranflated  from  the  bul- 
letin of  the  Soci(4d  Fhiloraati^ue,  No.  i8,  year  VI. 

being 


On  the  Fojpl  Boiiei  of  extinct  Speaes.  y  i  j 

feeing,  more  obtufe,  and  the  laminse  of  which  its  grinders  are  compofed  being  thinner.  The 
true  analogous  living  animal  is  not  known,  though  it  has  been  hitherto  confidered  as  the  or- 
dinary elephant.  ■ 

2.  The  animal,  of  which  the  remains  are  found  on  the  banks  of  the  Ohio  in  North  Ame- 
rica, which  the  Americans  and  Englifh  have  alfo  named  mammouth,  though  it  differs  much 
from  the  former.  Remains  of  this  animal  are  alfo  found  in  Europe  and  in  Afia.  It  mufl;  ■ 
have  been  nearly  the  height  of  the  elephant,  but  more  bulky;  its  tufks  are  fmaller;  its 
grinders  are  armed  with  large  cutting  points,  of  which  the  feSion  by  wear  prefents  double 
tranfverfal  lozenges.  There  are  three  molar  teeth  on  each  fide,  one  of  four,  one  having  fix, 
and  one  eight,  points. 

3.  The  animal  of  which  the  teeth  tinged  by  copper  afford  the  turquois  ftone,  and  of  which 
there  was  a  mine  at  Slmore,  in  Languedoc.  The  remains  of  this  fame  fpecies  is  found  in 
the  department  of  Ain,  in  Pcfu,  and  elfewhere.  It  muft  have  confidcrably  refembled  the 
former,  but  the  points  of  its  molar  teeth  are  round,  and  when  worn,  their  feftion  prefents, 
firft,  a  circle,  then  a  femi-oval,  and  afterwards,  a  figure  of  a  trefoil,  which  has  caufed  them 
to  be  confounded  with  the  teeth  of  the  rhinoceros :  fome  of  thefe  teeth  have  twelve  points, 
others  fix,  others  four. 

4.  The  rhinoceros.  The  feet  and  fragments  of  the  jaws  of  this  animal  are  found  in 
Trance,  and  elfewhere,  in  which  the  author  has  hitherto  obferved  nothing  which  differs  from 
the  common  rhinoceros ;  but,  as  he  has  not  yet  fcen  an  entire  bone,  he  cannot  pofitively  af- 
firm that  they  are  identical. 

5.  The  fpecies  of  rhinoceros,  with  an  oblong  craneum,  which  is  found  in  Siberia,  Ger- 
many, and  other  countries.  The  author  has  feen  teeth,  and  parts  of  the  jaw-bones,  found 
in  France,  which  appeared  to  him  hkewife  to  belong  to  this  animal ;  the  principal  character 
of  this  fpecies  confifls  in  the  long  clofure  of  the  nofe :  the  living  analogous  animal  is 
unknown.  » 

6-  A  molar  tootn  with  tvro  tranfverfal  eminences,  which  is  in  the  pofTeffion  of  Citizen 
Gillet ;  and  of  which  the  Naticmal  Mufeum  pofleffes  a  young  tooth  that  refembles  neither  the 
teeth  nor  the  germs  of  any  animal  yet  known,  whether  living  or  foffilc:  the  only  tooth 
•which  this  flightly  refembles  is  the  laft  molar  tooth  of  the  rhinoceros.  This  tooth,  there- 
fore, indicates  the  exiftcnce  of  a  fixth  foffde  fpecies,  of  which  the  living  analogous  animal  is 
unknown. 

"7.  The  animal,  twelve  feet  in  length,  and  fix  in  height,  of  which  the  fkeleton  was  found 
under  ground  at  Paraguay,  and  is  preferved  in  the  royal  cabinet  at  Spain,  at  Madrid.  The  au- 
thor proves  by  a  detailed  comparifon  of  the  bones,  with  thofe  of  all  the  known  quadrupeds, 
that  it  is  a'proper  and  difiin£l  fpecies,  more  nearly  approaching  the  floth  than  any  other  genus, 
and  that  it  may  be  called  the  giant  floth.  Citizen  Cuvier,  in  this  place,  communicates  the 
interefting  difcovery  he  has  made,  that  the  floth  (bradypus  tridaBybus,  Lin.)  has  naturally 
rand  conftantly  nine  cervical  vertebrae.  It  is  the  firft  known  exception,  eftablillied  by  Citizen 
Cauberton,  that  all  quadrupeds  have  neither  more  nor  lefs  than  feven  cervical  vertebrae. 

8.  The  animal,  of  which  the  remains  are  found  in  the  caverns  near  Gaylenreuth  and 
Muggendorf,  in  the  margraviate  of  Bayreuth,  in  Franconia.  Various  authors  have  confi- 
dered 


514  F^tl  Bones  of  extinB  species  of  Animals. 

deved  it  as  a  white  bear ;  but  it  difFers  from  this  animal,  as  well  as  from  all  the  known 
bears,  in  the  form  of  its  head,  which  is  particularly  charadierized  by  the  projeflion  of  the 
front,  by  the  abfence  of  the  fmall  tooth,  which  all  the  known  bears  have  behind  each  canine 
tooth,  by  the  ofleous  channel  of  the  humerus,  in  which  the  brachial  artery  pafles ;  and  by 
feveral  other  circumftances  in  the  figure  and  proportion  of  the  bones.  This  animal,  how- 
ever, refembles  the  bear  more  particularly  than  any  other  kind. 

9.  The  carnivorous  animal  of  which  the  bones  are  found  in  the  plaifter-ftone  of  Monte- 
martre :  the  form  of  its  jaws,  the  number  of  its  molar  teeth,  and  the  points  with  which  they 
are  armed,  indicate  that  this  fpecies  is  referrible  to  the  genus  canis ;  but  It  does  not  com- 
pletely refemble  any  fpecies  of  this  genus.  The  moft  ftriking  diftinftive  mark  is  that  the 
feventh  molar  tooth  is  the  greateft  in  the  animal  of  Montemartre,  whereas  the  fifth  is  the 
largeft  in  dogs,  wolves,  foxes,  &c. 

1  o.  The  animal  of  which  the  lower  jaw  was  found  near  "^erona,  has  been  confidered  by 
Jofeph  Monti  as  a  portion  of  the  cranium  of  the  fea-cow ;  a  notion  which  all  the  geologifts 
have  adopted,  though  it  be  the  contrary  to  the  moft  fimple  notions  of  comparative  anatomy. 
This  jaw,  according  to  Cuvier,  has  belonged  to  an  animal  refembling,  though  fpecifically 
different  from,  the  mammouth,  the  animal  of  the  Ohio,  and  that  of  Simore.  Its  moft  particu- 
lar character  confifts  in  the  curve  which  forms  its  fymphyfis. 

1 1 .  The  animal  of  the  ftag  kind  of  which  the  bones  and  the  antlers  are  found  in  Ireland, 
in  England,  at  Maeftricht,  &c.  It  is  fufficiently  different  from  all  the  ftags,  and  even  the 
elk,  to  which  it  has  been  referred,  by  the  enormous  magnitude  of  its  antlers,  the  flattening 
of  their  fuperior  part,  and  the  branches  which  fpring  from  their  bafe.  Several  figures  of  thefe 
are  given  in  the  Philofophical  Tranfadtions. 

1 2.  The  genus  of  the  ox  or  beeve  alone  affords  feveral  folFil  fpecies :  the  craniums  of  two 
Vere  found  in  Siberia,  which  have  been  defcribed  by  Pallas,  who  referred  one  of  them  to  the 
ordinary  buffalo ;  but  he  has  fince  attributed  them  to  a  peculiar  fpecies,  natives  of  Thibet, 
named  arni.  Citizen  Cuvier  proves,  by  ofteologic  comparifon,  that  thofe  craniums  have 
not  belonged  to  the  buffalo.  The  other  appeared  to  Pallas  to  have  belonged  to  the  buffalo 
of  the  Cape,  or  the  mufk  ox  of  Canada.  Citizen  Cuvier  fhews  that  they  cannot  have  be- 
longed to  the  former,  but  not  being  in  pofTeflion  of  the  cranium  of  the  arni,  nor  the  mufk 
ox,  he  makes  no  decifion  refpedting  their  identity  with  the  fofftle  craniums. 

The  author  likewife  defcribes  two  kinds  of  craniums  which  have  been  found  in  the  turf 
pits  of  the  department  of  La  Somme,  which  greatly  refemble  our  common  ox,  and  that  of 
L'Aurouchs,  but  are  more  than  one  fourth  longer. 

From  this  enquiry,  the  Citizen  Cuvier  concludes,  i.That  it  is  not  true  to  affirm  that  the  ani- 
mals of  the  fouth  have  formerly  lived  in  the  north,  their  fpecies  not  being  perfedly  identical. 
a.  That  in  every  country  there  have  lived  animals  which  do  not  at  prefent  exift,  either  on 
the  fame  fpot,  or  elfewhere  in  any  known  country.  Hence  he  leaves  to  geologifts,  the  tafk 
of  making,  in  their  fyftems,  fuch  changes  or  additions  as  they  may  think  beft  fuited  to  ex- 
plain the  fa^s  which  he  has  thus  eftabliihed. 


EKtraSl 


On  iie  Soluim  and  Oxygenation  cf  Tift,  515 

XIV. 

ExtraB  of  a  Memoir  of  Proujiy  entitled  Enquiries  concerning  Tin.     By  CITIZEN  DaRCET,* 

H  E  author  of  this  memoir  obferves,  in  the  firft  place,  that  he  confiders  his  work  as  a 
fupplement  to  that  of  Pelletier,  on  the  different  degrees  of  oxygenation  which  tin  can  acquire, 
when  diflblved  in  acids. 

When  tin  is  diflblved  without  heat,  in  very  weak  nitric  acid,  it  acquires  a  degree  of  oxygena- 
tion, different  from  that  which  it  would  obtain  if  diflblved  in  a  concentrated  acid,  or  if  heat 
had  been  employed.  In  the  firft  cafe,  the  nitric  acid  is  not  decompofed,  and  afibrds  but  little 
oxygen;  but  this  is  not  the  cafe  with  the  water,  which  in  fad,  afibrds  the  quantity  necelTary 
for  its  oxygenation. 

This  folution,  which  is  of  a  yellow  colour,  gradually  precipitates,  more  efpecially  if  it  be  heat- 
ed, and  the  feparation  of  the  tin  is  made  without  re-a£tion,  for  there  is  no  difengagement  of 
nitrous  gas ;  and  if  it  be  faturated  with  cauflic  pot-afb,  there  is  a  difengagement  of  ammoniac, 
as  was  already  obferved  by  Bayen  and  by  Pelletier.  The  oxyde  of  tin,  as  well  that  portion 
which  remains  fufpended  in  the  fluid,  as  that  which  is  precipitated,  and  re-diflblved  in  muriatic 
acid,  equally  decompofe  the  fuperoxygenated  muriate  of  mercury,  and  the  mercurial  oxydes, 
&c.  being  very  different,  in  this  refpedt,  from  the  oxyde  of  tin,  which  is  precipitated  from  the 
folution,  in  concentrated  nitric  acid,  or  the  folution  which  has  been  made  with  heat.  In  this, 
the  nitric  acid  is  decompofed,  and  the  precipitate  is  infoluble  in  the  muriatic  acid,  and  no 
longer  a£ls  upon  corrofive  fublimate,  or  the  oxydes  of  mercury.  This  difference  arifes  from  the 
circumflances,  that  in  the  firfl  cafe,  the  oxyde  of  tin,  whether  it  remain  in  the  liquor,  or  fall 
down,  is  oxyded  to  the  minimum,  as  Prouft  affirms,  and  in  the  fecond  cafe,  to  the  maximum. 
Hence  it  is,  that  in  the  firfl  cafe,  there  is  no  difengagement  of  elallic  fluid,  whereas  in  the 
fecond,  the  difengagement  is  conC4erable. 

When  an  acid  of  the  ftrength  of  25  or  30  degrees  is  ufed  (fp.  gr.  1,23),  the  folution  is  fa 
violent,  that  there  does  not  remain  an  atom  of  tin  in  the  fluid,  but  the  precipitate  is  oxyded  to 
40  parts  of  oxygen ;  but  when  the  very  weak  nitric  acid  is  ufed,  or  the  folution  is  made  with- 
out heat,  the  metal  is  oxyded  only  to  30. 

It  is  afcertained  by  hepatic  water,  that  all  the  tin  is  feparated  from  the  acid;  for  this  re-agent, 
will  totally  precipitate  tin,  copper,  or  lead,  if  the  fluid  contain  any.  Prouft  has  obferved,  that 
this  re-agent  may  prove  eminently  ufeful.  For  example,  fuppofe  a  folution  to  contain  lead, 
copper,  zinc  and  iron,  the  hepatic  liquor  will  feparate  them  all  in  fucceflion;  firfl  the  copper, 
then  the  lead,  next  the  zinc,  and  laft  of  all  the  iron,  with  jhis  remarkable  event,  that  the  iron 
which  was  oxyded  to  the  maximum  in  the  folution,  is  thrown  down  at  the  minimum,  and  is 
precipitated  green,  by  ammoniac  and  by  lime.  This  happens,  becaufe  the  hepatic  water  feizes 
a  portion  of  the  oxygen  from  the  oxyde,  and  becomes  decompofed,  leaving  the  iron  at  the  lefs 
degree  of  oxygenation. 

It  is  known,  that  very  fetid  hydrogen  is  extricated,  during  the  folution  of  tm  in  the  muri- 

*  Annales  de  Chimie,  XXVIII.  113. 

atlc 


$t6  OnthtOxyiaiionofTtn,^i:. 

atic  acid,  jJarticiilatly  wlien  the  tin  contains  arfenic,  which  may  be  very  Well  afcertained,  {ly 
turning  the  gas  under  a  glafs  veflel,  when  the  arfenic  is  depofited  on  the  fides.  Prouft  alfo 
obferves,  that  this  gas  is  very  hurtful  to  the  brlghtnefs  of  the  purple  of  powder  of,  caflius- 
He  therefore  very  properly  advifes,  that  the  folution  fliould  be  heated  before  it  is  ufed:  an 
obfervation  of  the  greateft  importance  for  porcelain  and  enamel  painters. 

If  a  few  drops  of  the  moriate  of  tin,  be  added  to  the  muriatic  acid  of  commerce,  the 
yellow  colour  of  the  latter  inftantly  difappears.  The  tin  deprives  the  iron  of  the  excefs  of 
oxygen,  which  rendered  it  red,  and  ammoniac  then  precipitates  it  of  a  green  colour.  The  fame 
thing  happens  with  the  folutions  of  the  fulphates,  nitrates,  and  red  muriates  of  iron. 

But,  if  a  ftroriger  dofe  of  muriate  of  tin  be  poured  into  the  muriatic  acid  of  commerce,  a 
grey  powder  falls  down,  which  Prouft  has  afcertained  to  be  mercury. 

When  a  folution  of  the  muriate  of  tin  is  diftilled,  the  whole  of  the  liquid  comes  over,  with 
a  portion  of  the  muriate.  Towards  the  end,  the  matter  fwells  up,  and  afterwards  f:ttles  in  the 
flate  of  calm  fufion,  of  a  green  colour;  and  if  the  fire  be  raifcdj  pufFs  of  fuming  vapour  are 
driven  ofF,  but  nothing  comes  oVer  in  the  fluid  form.  If  the  muriate  of  tin  contains  a  fmalf 
portion  of  fulphuric  acid,  that  acid  is  decompofcd,  and  the  fulphur  partly  unites  with  the  tin, 
forming  a  fulphuret,  in  vi'hich  the  tin  is  oxyded  to  the  minimum.  This  muriate  requires  a 
ftronger  heat  for  its  diftillation,  than  the  fmoking  muriate  irt  the  ordinary  procefs. 

But  that  fubftance  which  rifes,  and  is  condenfed  in  the  neck  of  the  retorts,  proves,  after 
wafiiing,  and  feparating  the  fuming  muriatcj  to  be  nothing  but  tin  half  oxyded,  to  which  acid 
only  need  be  added,  in  order  to  diflblve  it  again.  This  diftilled  muriate  eiFeftually  decompofes 
the  fublimate  of  mercury,  and  all  the  mercurial  preparations,  or  oxydes;  while  the  fuming 
muriate,  being  oxyded  to  the  maximum,  dccompofes  nothing. 

The  muriate  of  tin  affords,  with  alcalis,  a  precipitate,  which  cauftic  pot^afli  abundantly  dif- 
folves.  This  folution  referved,  in  a  clofe  vefl'el,  at  the  end  of  1 2  or  15  days,  affords  a  metallic 
group,  in  the  form  of  cauliflowers,  which  confifts  of  tin,  nearly  pure^  In  this  procefs,  one 
part  of  the  tin,  oxyded  to  the  mininum,  robs  the  other,  and  becomes  falurated;  and  this  mu- 
riate of  tin,  fo  faturated,  is  no  longer  capable  of  altering  corrofive  fublimate. 

The  fame  thing  happens,  if  a  mixture  of  the  carbonate  of  copper,  and  the  oxyde  of  tin,  fe- 
parated  fromithe  muriate  by  pot-afh,  be  kept  under  water.  The  oxyde  of  tin  robs  all  the 
copper  of  its  oxygen,  aiid  the  portion  of  carbonic  acid;  whence  the  copper  is  found  reduced, 
in  cryftalized  plates,  among  the  oxyde  of  tin. 

Laftly,  the  muriate  of  tin  difoxygenates  indigo,  and  changes  it  to  grcert.  This  experiment 
is  analogous  to  other  difoxygenations  of  the  fame  fecula,  known  to  dyers.  ProUft  mentions 
<his  circumftance  as  an  obje(Sl  deferring  of  great  attention,  upon  which  he  means  to  malce 
-further  refearches. 

The  fulphates,  nitrated,  muriates,  acetates,  and  carbonates,  of  copper,  and  alfo,  the  red, 
blue,  or  green  oxydes,  mixed  vvith  the  muriate  of  tin,  are  generally  converted  into  a  white 
oxyde,  which  is  collefted  at  the  bottom  of  the  vefTel;  and  if  this  muriate  be  palTed  again  upon 
a  new  oxyde,  it  becomes  itfelf  green,  and  is  faturnted  to  fuch  a  degree  as  no  longer  to 
alter  the  colour  of  oxydes.  The  powder,  thus  robbedliy  the  muriate  of  tin,  afTumes  differ- 
ent fhades  of  colours,  violet,  blue,  black,  &c.  which  are  more  particularly  governed  by  the 
-    ,  degree 


On  the  Oxydation  of  Tin  and  other  Metals.  5 1 7 

degree  of  expofure  to  light.     It  is  fufible  by  heat,  and  affumes  the  appearance  of  a  muriate- 
of  filver,  in  which  ftate  Proufl  propofcs  to  keep  it. 

The  fulphuric  acid  has  no  aftion  on  this  fubftance,  but  the  muriatic  acid  immediately  dif- 
folves  it,  and  it  cryftallizes  in  tetrahedrons.  The  nitric  acid  alfo  diflblves  it,  during  which 
it  pafll;s  through  various  fliades  of  colour ;  but  at  lad  it  retains  the  appearance  of  a  folution 
of  nitrate  of  copper,  in  which  the  prefcncc  of  muriatic  acid  may  be  eafily  detcdled.  But  the 
difengagement  of  nitrous  gas  which  'takes  place  during  the  folution,  proves  that  it  is  not 
faturated  with  oxygen. 

Prouft,  obferving  that  this  muriate  was  without  colour,  and  that  it  was  alfo  foluble  in  am- 
moniac without  colouring  it,  thought  at  firft  that  he  might  conclude,  contrary  to  the  prin- 
ciple eftabliflied  by  Lavoifier,  that  the  copper  was  abfolutely  clear  of  oxygen  ;  but  the  ana- 
lyfiS  which  he  made  foon  undeceived  him. 

He  diffolved  100  grains  of  this  white  fufed  muriate  in  very  pure  nitric  acid,  which  he 
afterwards  precipitated  by  the  nitrate  of  filver,  and  obtained  142  grains  of  muriate  of  filver, 
which  reprefent  24 4:  grains  of  marine  acid.  On  the  other  hand,  100  grains  of  very  white 
muriate  of  filver  treated  with  nitric  acid,  and  carbonate  of  pot-afh,  afforded  him  113  grains 
of  carbonate  of  copper,  which,  according  to  experiment,  anfwer  to  62-J,  or  63  of  copper,  fo 
that  from  his  analyfis  he  found  thefe  produ£ts: — marine  acid  24^;  oxyde  of  tin  i ;  copper  63  j 
and  the  i\\  deficiency  remain  for  oxygen. 

Whereas  he  was  fatisfied,  that  in  the  green  muriate,  in  the  fulphate,  in  the  nitrate,  and  in 
the  acitite  of  copper,  the  metal  which  is  at  the  maximum  of  oxygenation,  contains  about  26 
of  oxygen  in  the  centenary. 

Laftly,  it  is  proved  that  while  the  copper  is  oxyded  no  farther  than  1 7  or  18,  its  folutions 
are  white,  and  it  cannot  then  give  colour  either  to  its  muriate,  or  to  ammoniac. 

The  following,  as  Proufb  informs  us,  is  another  proof  of  the  prefence  of  oxygen  in  this 
white  powder.  If  a  fmall  quantity  be  put  into  water  with  iron  filings,  the  copper'  foon  fepa- 
rates,  and  the  iron  becomes  oxyded  to  the  minimum,  fo  that  when  diflblved  the  alcalies  pre- 
cipitate it  of  a  green  colour. 

If  it  be  demanded  whence  the  oxygen  comes  in  the  white  folution  of  copper  in  the  muri- 
atic acid,  Prouft  replies,  that  it  is  from  the  water.  The  water  is  decompofed,  as  Berthollet 
had  before  fhewn.  The  oxygen  combines,  and  oxydes  the  copper.  Prouft  even  relates  an 
experiment  in  which  the  hydrogene  of  the  water  was  rendered  perceptible  to  the  fmell,  by 
the  affiftance  of  a  fmall  quantity  of  fulphur  which  was  formed,  and  was  diflblved  and  volati- 
lized with  the  hydrogene.  This  experiment  confifts  in  boiling  the  blue  fulphate  of  copper 
in  muriatic  acid.  A  folution  is  obtained,  which  is  precipitated  by  water,  during  which  the 
hydrogene  becomes  perceptible  to  the  fmell. 

When  a  green  muriate  is  diftiiled,  it  may  eafily  be  brought  to  the  point  of  cryftallization  j 
but  if  the  diftillation  be  carried  further,  it  is. decompofed,  and  lofes  the  portion  of  oxygen, 
which  makes  the  difference  between  the  oxyde  containing  25  parts,  and  that  containing  only 
1 8  ;  but  the  diftillation  then  affords  oxygenated  muriatic  gas.  At  length  tliis  gas  ceafes, 
and  there  remains  at  the  bottom  of  the  retort  a  grey,  well-fufed  mafc,  which  is  the  white 
muriate  of  copper.  This  is  an  eafy  method  of  procuring  the  white  muriate.  Prouft  adds. 
Vol.  II— Feb.  1799.  h,  X  that 


5 1 8'  Oxygeaation  of  Metals, — Difference  hctivcen  the  Acetous  and  Acetic  Acids. 

that  the  copper  iu  the  green  fand  of  Peru,  ;uid  in  the  native  muriate  of  Chili,  are  in  this 
(late. 

It  is  of  importance  to  remark,  that  the  chemill  might  be  induced  to  believe,  that  when 
a  metallic  fubllance  is  difoxygenated  in  any  manner  whatever,  whether  by  the  applicatioa 
of  ftrong  heat,  or  by  the  affinities  of  other  metals  for  oxygen  •,  or,  in  the  manner  of  Proult, 
by  hepatic  gas,  as  happens  in  the  difoxygenation  of  the  tunitic  and  molybdic  acids;  the 
chemifl  might  think,  that  thefc  fubftances,  at  their  tranfition  to  the  violet  blue,  or  black 
colour,  were  reduced  to  the  metallic  ftate  :  but  the  effeft  is,  as  he  remarks,  merely  an  incom- 
plete difoxygenation.  The  metal  is  merely  depreffed  to  the  minimum,  as  happens  with  iron 
and  copper,  when  by  various  means  diey  are  brought  from  their  entire  ftate  of  oxygenation, 
to  that  in  which  the  colour  becomes  blue,  black,  or  red,  more  or  lefs  deep.  There  are  no 
metals  b«t  mercury,  gold,  and  arfenic,  in  which  a  complete  difoxygenation  is  obferved. 

But  to  return  to  tin :  Prouft  has  found,  with  Bergman,  that  tin  oxyded  to  the  minimum 
acquired  no  more  than  an  addition  of  30  parts  in  the  hundred,  and  even  in  this  ftate  is  not 
exempt  from  marine  acid.  If  it  be  ignited  in  a  crucible  it  lofes  weight,  and  emits  the 
vapours  of  muriate  of  tin  ;  and  when  the  tin  is  oxyded  to  the  maximum  it  is  charged  with  40 
pci  cent.  But  it  is  eafy  to  reduce  it  30,  in  which  ftate  it  is  blueifli,  and  infoluble  in  acids. 
The  author  here  terminates  his  memoir,  by  remarking,  that  although  Pelletier  has  not  men- 
tioned the  white  muriate  of  copper,  he  is  not  lefs  perfuaded  that  it  -Svas  known  to  that 
chemift  ;  and  this  more  particularly,  becaufe  he  has  fpoken  flightly  of  the  difoxydation  of  that 
metal  by  tin,  as  if  he  meant  to  fpeak  more  fully  on  another  occafion.  But  while  he  renders 
this  juftice  to  Pelletier,  he  affirms  with  the  open  freedom  of  truth,  that  though  his  refults 
coincide  with  thofe  of  that  chemift,  they  were  not  undertaken  fubfequent  to  his  experiments. 

There  are  a  great  number  of  otlier  fails  and  obfervations  in  the  Memoir  of  Prouft  which 
defei-ve  to  be  related ;  but  the  abundance  and  denfity  of  thefe  fa£ls  are  fuch,  that  tlie 
attempt  to  communicate  them  would  convert  this  abridgement  into  a  memoir  no. lefs  ample 
than  the  original. 


XV. 

Obfervations  on  the  Dlffirences  which  exijl  between  the  Acetous  and  Acetic  Acids.     By  J.  A. 

Chaptal.* 


T, 


H  E  acid  of  four  wine  prefents  to  our  obfervation  two  very  diftimSi  ftates,  which  arc 
known  by  the  names  of  the  acetous  and  the  acetic  acids. 

Chemifts  have  hitherto  referred  this  difference  to  the  varying  proportion  between  the 
oxygen  and  the  radical,  and  it  has  generally  been  believed,  that  the  acetic  acid  differs  from 
the  acetous  fimply  in  a  ftronger  dofe  of  the  acidifying  principlef. 

Citizen  Adet  has  refumed  this  interefting  refcarch,  and  has  prefented  to  the  foeiety  a  courfe 
of  experiments,  from  which  he  concludes  : 

•  Annales  de  Chimie,  XXVIII.  113. 
t  We  may  except  Citizen  Peres,  who,  in  the  Journal  des  Pharmaciens,  has  anntunced,  that  the  difference 
Wtween  the  acetous  and  acetic  acids  confifts  in  the  proportion  of  cirbone.— C. 

I.  That 


Diffinnce  between  the  Acetous  and  Acetic  Acids.  519 

T .  That  no  fuch  thing  as  the  acetous  acid  exifts. 

2.  That  the  acid  of  vinegar  is  always  at  the  higheft  poffible  degree  of  oxygenation ;  and, 
Confequently,  is  always  acetic. 

3.  That  the  difference  between  the  acid  obtained  by  the  diflillation  of  vinegar,  and  that 
afforded  by  the  like  procefs  from  the  acetate  of  copper,  depends  on  the  lefs  quantity  of  water 
•contained  in  the  latter.  , 

I  muft  confefs,  that  notwithftanding  the  high  degree  of  confidence  I  place  in  the  labours  of 
Citizen  Adet,  it  has  been  impoffiblc  for  me  to  adopt  his  conclufions  in  this  refpeft  ;  and  as  I 
was  very  far  from  calling  his  experiments  in  queftion,  I  have  thought  it  proper  to  analyfe, 
compare,  and  difcufs,  his  refults,  much  lefs  with  the  view  of  afcertaining  their  accuracy, 
than  to  dcterrtiine  whether  they  juftify  the  confequences  deduced  from  them  by  their  author. 

I  conclude,  therefore,  immediately  with  Citizen  Adet,  that  it  appears  to  be  demonftrated 
by  his  experiments,  that  the  oxygen  exifts  nearly  in  equal  proportions  in  the  diftilled  acetous 
acid  and  the  acetic  acid  ;  that  it  is  equally  difficult,  and  even  impoffible,  to  oxygenate  the 
acetous  acid,  and  to'  difoyxgenate  the  acetic ;  and  that  moft  of  the  fait  feparately  formed  by  thefe 
two  acids  are  of  the  fame  nature.  Thefe  confequences,  no  lefs  new  than  interefting,  belong 
to  Citizen  Adet,  and  naturally  flow  from  his  experiments. 

But  to  conclude,  from  the  fame  fafts,  that  the  acetous  and  the  acetic  acids  are  exaCtly  the 
fame,  and  differ  only  in  their  proportions  of  water,  is  more  than  the  experiments  will  juftify ; 
and  while  we  muft  agree  with  Citizen  Adet  as  to  the  truth  of  his  firft  confequences,  it  may 
alfo  be  fhewn,  that  there  is  a  very  great  difference  between  the  acetous  diftilled  acid,  and  the 
acetic.     I  fliall  endeavour  to  afcertain  the  caufe  of  this  difference. 

The  two  acids  in  queftion  differ,  no  doubt,  in  fmell,  in  tafte,  and  folvent  power ;  but  as 
the  caufe  of  thefe  differences  might  be  referred  to  their  refpective  degrees  of  concentration, 
I  have  thought  it  proper  to  bring  both  to  the  fame  fpecific  gravity,  by  diluting  the  acetic  acid 
with  a  fufficient  quantity  of  diftilled  water ;  and  it  was  with  thefe  two  acids,  at  the  fame 
degree,  that  I  made  the  following  obfervations  and  experiments : 

1 .  The  fmell  and  tafte  fliew  the  difference  between  thefe  two  acids.  The  effe£ls,  in  this 
refpe£t,  are  more  evident,  and  the  fenfation  is  much  more  penetrating  on  the  part  of  the 
acetic  than  the  acetous  acid. 

2.  The  adtion  of  the  acetic  acid  on  the  lips,  and  upon  the  metallic  oxydes,  is  more  fpeedy 
and  energetic  than  that  of  the  acetous  acid.  Thefe  two  acids,  fet  to  digeft  in  equal  portions 
upon  the  oxyde  of  copper,  precipitated  fr<5m  the  fulphate  by  pot-afti,  wafhed,  and  then 
diftilled,  prefented  very  different  refults.  The  acetic  acid  diffolved  the  oxyde,  and  formed 
beautiful  cryftals  by  cooling ;  but  the  acetous  was  fimply  coloured  of  a  blueifh  green,  and 
let  fall  nothing  but  a  green  faline  cruft,  on  the  borders  of  tlie  fluid. 

Neither  of  thefe  acids  perceptibly  attacked  copper.  They  merely  acquired,  by  long 
digeftion,  a  light  green  fhade  of  colour. 

Eleven  parts  of  the  acetic  acid  required  for  their  faturation  6,98  of  pure  pot-afti ;  the 
fame  quantity  of  acetous  acid  required  only  5,73- 

There,  confequently,  exifts  a  difference  between  thefe  oxydes.  The  following  experiments 
will  fhew  in  what  this  difference  confifts,  and  render  us  acquainted  with  its  caufe : 

3X2  ■      ^  I.  If 


5io  Diffc-etut  between  the  Acetoui  and  Acetic  Ac'idi. 

I.  If  fulphuric  acid  be  poured  on  the  concentrated  acetic  acid,  and  then  diltillcd,  the  fiid 
confequence  is  the  produftion  of  confiderable  heat,  the  colour  of  the  mixture  becomes  red, 
and  increafes  in  intenfity,  until  at  length  it  becomes  black.  A  great  quantity  of  carboae  is 
precipitated  by  the  continued  a£tion  of  the  heat,  at  tlie  fame  time  that  much  fulphureous  gas 
is  difengaged. 

II.  I  put  feparately  into  two  glafs  retorts  equal  parts  of  the  acetic  and  acetous  acids,  at  the 
fame  degree  of  concentration ;  I  poured  upon  each  one-fourth  of  its  weight  of  fulphuric  acid. 
This  mixture  produced  a  very  flrong  heat. 

The  colour  of  the  mixture  of  fulphuric  acid  with  the  acetic  acid  at  firfl  appeared  of  a  pale 
yellow,  while  that  of  the  acetous  acid  did  not  change  colour. 

The  mixture  of  acetous  acid  arrived  at  the  point  of  ebullition  fooner  than  the  other. 
It  became  yellow  after  the  evaporation  of  one-third  of  the  fluid,  and  its  colour  grew  deeper 
and  deeper,  until  it  had  acquired  the  tinge  of  highly-coloured  wine. 

The  mixture  of  the  acetic  acid  was  not  coloured  in  the  fame  proportion,  and  it  never  ac- 
quired a  deeper  tinge  than  that  of  ftraw-colourcd  white  wine. 

The  diflillation  being  long  kept  up,  and  urged  by  a  ftrong  fire,  caufed  copious  white  vapours 
of  fulphureous  acid  to  pafs  over ;  and  towards  the  end  the  two  refidues  became  colourlefs, 
and  contained  nothing  but  the  concentrated  fulphuric  acid. 

The  two  firft  third  parts  of  the  producl  of  the  diflillation  had  nearly  the  fame  fmell  and 
tafte,  and  the  acetous  acid  appeared  to  me  to  have  been  brought  to  the  ftate  of  acetic  acid  by 
its  decarbonization  in  the  retort. 

III.  I  faturatcd,  with  pure  pot-afh,  loo  pots  of  each  of  thefe  two  acids,  and  put  the  foln- 
tion  to  evaporate,  and  obtained,  from  both,  white  foliated  deliquefcent  falts.  I  put  equal 
parts  of  each  of  thefe  falts  into  two  retorts,  and  expofed  them  to  an  equal  heat,  which  was 
gradually  increafed  till  it  became  violent.  There  pafled  at  firft  into  the  receiver  of  the  ap- 
paratus in  which  the  acetate  was  placed,  two  or  three  drops  of  offenfive  fmelling  acrid 
water,  which  indicated  no  acidity  to  the  tafte.  The  diftillation  of  the  acetite  produced 
nothing  but  certain  vapours,  which  emitted  a  fimilar  odour. 

The  fait  was  firft  liquified,  and  then  became  black,  in  both  the  retorts.  In  proportion  as  I 
increafed  the  heat,  the  retorts  and  receivers  became  lined  with  a  white  fume,  which  after- 
wards difappeared. 

In' both  retorts  were  left  black  refidues,  upon  which  I  poured  boiling  diftilled  water.  I 
wafhed  them  feveral  times,  in  order  to  deprive  them  of  all  foluble  matter. 

Thefe  refidues  being  dried,  prefented  all  the  charadters  of  carbone.  Their  weight  com- 
pared with  that  in  fait  made  ufe  of,  afforded  the  following  refults  : 

The  acetate  afforded  one-feventeenth  part  of  its  weight  in  carbone. 

The  acetite  afpjrded  one-thirteenth  part. 

There  is,  confequently,  a  difference  between  the  acetous  and  the  acetic  acids;  and  this 
difference  arifes  from  the  greater  proportion  of  carbone  in  tlte  acetous  beyond  that  in  the 
acetic  acid. 

It  appears  to  me,  that  the  phenomena  prefented  by  the  diftillation  of  the  acetite  of  copper, 
ought  to  lead  us  to  the  fame  confequence.     In  faft,  the  acetite  of  copper  is  merely  a  folution 

of 


Difference  between  the  Acetous  and  Acetic  Acids.  52 1 

of  the  oxyJe  of  copper  in  the  acetous  acid,  and  when  this  fait  is  diftilled,  the  acetous  acid  is 
decarbonated.  Part  of  the  carbone  combines  with  the  oxygen  of  the  oxyde  of  copper,  and 
efcapes  in  the  form  of  carbonic  acid ;  while  the  other  part  remains  in  its  folid  form  in  the 
retort  along  with  the  oxyde  itfelf.  The  acetous  acid,  thus  deprived  of  a  portion  of  its  car- 
bone,  paffcs  into  the  receiver  with  charafters  which  no  longer  appertain  to  the  acetous  acid, 
and  the  oxyde  of  copper  is  nearly  reduced  to  the  metallic  ftate. 

The  acetous  does  not  therefore  become  acetic  acid,  but  by  a  fubtra£llon  of  carbone.  It 
appears  that  the  metallic  oxydes  alone,  and  fome  of  the  acids,  are  capable  of  elFedting  this 
decompofition. 

The  acid  appears,  therefore,  to  exift  in  the  ftate  of  acetous  acid  in  the  fait  of  copper,  im- 
properly called  acetite.  It  does  not  become  acetic  acid  but  by  diftillation,  becaufe  it  is  by 
this  procefs  only  that  it  lofcs  a  portion  of  its  carbone. 

Independent  of  the  proofs  we  have  exhibited  in  fupport  of  this  truth,  we  may  adduce  the 
two  following  fa£i:s : 

I .  When  verdigreafe  is  manufactured  with  the  diftilled  acetous  acid  of  copper,  a  pure  fait 
is  obtained,  which  affords  by  diftillation  the  fame  produils  as  the  cryftals  of  Venus,  or  the 
acetate  of  copper.  I  have  mentioned  this  fafl:  in  a  memoir  concerning  the  compound  pro- 
cefles  of  the  fabrication  of  verdigreafe.  2.  Every  one  knows  that  vinegar  is  fo  much  the 
ftronger,  and  more  completely  approaches  in  its  fmell  to  the  acetic  acid,  in  proportion  as  it 
is  more  completely  deprived  of  the  extraftive  matter  with  which  it  was  combined.  AVe  may, 
in  this  cafe,  confider  the  acid  of  vinegar  as  originally  exifting  in  a  ftate  nearly  faporaceous, 
which  diminilhes  its  aftion,  and  weakens  its  properties.     It  is  difengaged  from  this  addition, 

1 .  by  fimple  repofe,  which  fufFers  part  of  the  extra£tive  matter  to  precipitate,  or  fall  down  ; 

2.  by  the  fulphuric  acid,  which  decompofes  and  more  completely  carbonizes  the  extraftive 
matter  ;  3.  by  the  oxyde  of  copper,  which  retains  a  portion  of  the  fame  principle  with  which 
it  appears  to  form  a  pyrophoric  combination. 

I  was  defirous  of  afcertaining  whether  the  acetic  acid  could  be  brought  back  to  the  ftate 
of  acetous  acid,  by  caufmg  it  to  refume,  in  the  courfe  of  diftillation  upon  carbone,  that  por- 
tion which  it  had  loft :  but  all  the  methods  I  made  ufe  of  to  fucceed  in  this  refpedl  were 
inefFe6lual. 

From  the  preceding  fads  I  conclude  :  i.  That  there  is  a  difference  between  the  acetous 
and  the  acetic  acids.  2.  That  this  difference  arifes  from  a  fmaller  proportion  of  carbone  in 
the  acetic  acids,  than  in  the  acetous.  3.  That  the  acidis  in  the  acetous  ftate  in  metallic 
falts.  4.  That  it  does  not  pafs  to  the  acetic  ftate  but  by  decarbonization.  5.  That  the  dif- 
ference between  this  acid  and  fome  others,  equally  fufceptible  of  modifications  by  a  change 
in  the  preparation  of  their  conftituent  parts,  is,  that  in  this  the  oxygen  does  not  appear  fuf- 
ceptible of  addition,  or  fubtra£lion  ;  but  its  carbone  alone  undergoes  which  variation,  and  ' 
determines  all  its  changes  ;  whereas  in  the  other  acids  the  oxygen  is  the  principle  which  is 
more  particularly  fubjed  to  variation,  and  occaCons  the  changes  obfervable  in  their  properties. 


SCIENTIFIC 


522  Scientific  News. 

SCIENTIFIC  NEWS,  AND  JCCOUNT  OF  BOOKS. 
Lantern  Pinions  of  Glafs  for  Mlll-tvork. 

V>>ITIZEN  MOLARD  has  communicated  to  the  French  Inflitute  an  acoount  of  the  ad- 
vantages of  making  the  trundles  in  lantern  pinions  of  glafs,'  to  work  againft  the  hard  wooden 
teeth  of  wheels  in  mill-work.  The  trundles  are  fet  in  die  fame  manner  as  thofe  of  iron, 
only  taking  the  neceflary  care  which  the  nature  of  the  materia!  muft  require.  A  pinion  of 
this  kind,  in  which  the  trundles  were  two  inches  in  diameter,  did  not  undergo  the  leaft  wear, 
or  alteration  of  the  furface  of  the  glafs,  in  1 8  months'  ufe ;  and  the  wooden  teeth  had  loft 
about  one-twelfth  part  of  an  inch.  Iron  trundles  wear  out  the  teeth  in  about  four  months, 
and  load  the  work  with  much  more  friftion.  The  kinds  of  glafs  which  were  tried,  were 
green  window-glafs,  white  fheet-glafs,  and  the  white  glafs  for  goblets  (gobictrle).  Ihis  lafl 
was  the  hardeft  and  beft.  The  inventor,  Cit.  Renaut,  of  the  department  of  La  Meurthe, 
thinks  bottle-glafs  might  be  of  good  fervice.  He  does  not  blow  the  trundles,  but  makes 
them  folid.  It  is  probable,  that  with  us  the  glafs  of  wine  bottles  might  be  the  cheapcft,  and 
moft  valuable  for  its  hardnefs  and  tenacity,  if  it  can  be  eafiiy  wrought  to  the  figure  by  the 
workmen  who  are  employed  upon  it. — Decade  PhUof.  No.  5,  l^ear  VII. 


Itfllttite  of  the  Llgurlan  Republic. 

THE  lately  eftablifhed  Inftitute  of  the  Ligurian  Republic  is  compofed  of  72  members,  of 
which  36  are  refident,  and  36  aflbciates,  inhabitants  of  the  republic,  divided  into  two  clafles, 
and  each  of  thefe  into  three  feftions. 

The  firft  is  the  clafs  of  mathematical  and  phyfical  fciences,  of  which, the  three  fe<fl:ions  are: 
I.  Agriculture,  commerce,  and  manufactures.     2.  Nautical  fcience,  matliematics,  natural> 
philofophy,  and  natural  hiftory.     3.  Chemiftry,  botany,  anatomy,  medicine,  and  furgery. 

The  fecond  clafs  includes  (moral)  philofophy,  literature,  and  the  fine  arts  ;  of  which  the 
fediions  are  :  1 .  The  art  of  reafoning,  and  analyfis  of  the  operations  of  the  underftanding, 
grammar,  eloquence,  and  poetry.     2.  Politics,  hiftory,  and  antiquities.     3.  Arts  of  defign. 

On  the  14th  Brumaire  (Nov.  4)  the  Executive  Diredlory  of  the  Republic  repaired  to  the 
Hall  of  Seffion  of  the  Inftitute,  and  the  eftablifhment  was  opened  by  the  formality  of  pro- 
claiming tlie  members,  &c.  after  wliich  the  Inftitute  proceeded  to  choofe  their  prefident  and 
fecretaries,  and  to  organize  their  future  labours. 


.  Inflitute  of  Cairo.  * 

THE  learned  men  who  accompanied  Buonaparte  in  his  expedition  have  formed  a  national 
Inftitute  at  Cairo,  compofed  of  four  claffes,  each  confifting  of  twelve  members.  They  hold 
their  meetings  on  the  firft  and  fixth  day  of  each  decade. ^ 

The  names  of  the  members  of  each  clafs  are  as  under : 

Clafs  I.  Mathematics.  Andreofly,  Buonaparte,  Coftaz,  Fourier,  Gerard,  Lepere,  Leroi, 
Malus,  Monge,  Nouette,  Quefnot,  Say. 

*  From  the  Magazin  Encyclopedlcjue,  IV.  552.  Nivofe  VII. 

Clafs 


Scientific  News. — Account  of  Books,  e^-i 

Clajs  11.  Natural  Phllofophy.  Beauchamp,  Berthollet,  Champi,  Conte,  Deliflcj  Defcotils, 
Defgenettes,  Dolomieu,  JDubois,  GeofFroy,  Savigny.     (There  is  one  place  vacant.) 

Clafs  III.  Political  Economy.  CafFarelli-Dufalga,  Gloutier,  PoufTielgue,  Sulkowfky,  Sucy, 
Tallien.     (Six  places  vacant.) 

Clafs  IV.  Literature  and  the  Arts.  Denon,  Dutertre,  Nery,  Parceval,  Redoute,  Riegel, 
Venturi,  Raphael,  a  Greek  prieft.  '  (Four  places  vacant.) 

On  the  6th  Fruclidor,  in  the  year  VI.  (Aug.  23,  1798),  at  feven  in  the  morning,  the  Infti- 
tute  of  Egypt  held  its  firft  fitting,  at  which  Buonaparte  prefided.  The  officers  were  eleifted  : 
Monge,  prefident ;  Buonaparte,  vice-prefident ;  and  Fourier,  perpetual  fecretary  ;  in  whofe 
place,  on  account  of  his  abfence  at  Rofetta,  Coftaz  was  provifionally  appointed. 

In  this  firft  fitting  Buonaparte  made  the  following  propofitions  : 

1.  What  are  the  bejl  methods  of  Improving  the  conJlruSilon  of  ovens  to  bake  bread  for  the  army? 
The  commiffaries  named  to  examine  this  queftion  were,  Berthollet,  Caffarelli,  Say,  and 
Monge. 

2.  What  produEl  can  be  fuhjlltuted  Injlead  of  hops  In  making  beer?  Commiflaries,  Berthollet, 
Malus,  Coftaz,  Gloutier,  and  Defgenettes. 

3.  How  may  the  waters  of  the  Nile  be  clarified,  and  rendered  pure  ?  CommifTaries,  Monge, 
Berthollet,  Coftaz,  and  Venturi. 

4.  Are  wind,  or  water  mills,  to  be  preferred  ?  fin  the  prefent  ctrcuhiftances).  Commiflaries, 
Caffarelli,  Malus,  Say,  and  Coftaz. 

5.  What  are  the  refources  fir  procuring  gunpowder  ?  CommifTaries,  AndreofTy,  Malus,  and 
Venturi. 

6.  What  Is  the  fate  of  leglfiatlon  in  Egypt,  and  how  can  it  be  meliorated  ?  CommifTaries,  Say, 
Sulkowflcy,  Tallien,  and  Coftaz. 

7.  A  projeEi  of  regulation  (of  the  Infltute  ? )  CommifTaries,  Monge,  Caffarelli,  Tallien, 
Geoffroy,  Coftaz. 

(To  be  continued). 


Cafes  of  the  Diabetes  Mellitus,  with  the  Refults  of  the  Trials  of  certain  Acids,  and  other 
Subftances,  in  the  Cure  of  the  Lues  Venerea.  By  John  Rollo,  Surgeon-General,  Royal 
Artillery.     Second  Edition,  with  large  Additions. 

THE  fecond  edition  of  thjs  treatife  was  announced  at  p.  427  of  the  prefent  volume,  but 
time  did  not  then  permit  me  to  give  an  account  of  the  additions  and  fa£ts  now  firft  publifhed. 

The  additional  cafes  and  communications  on  this  diabetes,  appear  to  eftablifh  the  author's 
opinion  refpe£ling  the  efficacy  of  diet  confifting  entirely  of  animal  food,  when  rigoroufly 
perfevered  in.  The  difledtions  likewife  prove,  that  the  fweet  urine  does  not  proceed  from 
any  organic  afFeclion  of  the  kidneys,  but  moft  probably  from  fome  vitiated  ftate  of  the 
ftomach,  and  organs  of  digeftion. 

The  additional  cafes  are,  two  from  Dr.  Gerard  of  Liverpool;  a  continuation  of  Walker's  cafe, 
by  Dr.  De  la  Rive;  four  from  Dr.  Cleghorn  of  Glafgow,  with  a  continuation  of  his  former 
cafes;  fome  remarks  and  cafes  by  Dr.  Storer  of  Nottingham,  with  a  continuation  of  Dr. 
Aldricli's  cafe;    one  from  Dr.  Jamefon,  furgeon  of  the  Royal  Artillery;  one  from  Mr. 

Sherriff 


524  Account  of  Booh,  ^c. 

SherrifF  of  Deptford;  one  from  Mr.  Houften  of  London;  three  from  Dr.  Pearfon  of  St. 
George's  Hofpital,  with  remarks;  one  from  Dr.  Marlhall,  with  the  difleftion;  one  from  Dr. 
Willan;  and  one  from  Mr.  Thomas  of  Leicefter-fquare,  with  the  difleftion. 

Dr.  Rollo  informs  us,  that,  fmce  the  firft  difperfion  of  his  notes  on  Capt.  Meredith's  cafe, 
in  Jan.  1 797,  the  number  of  diabetic  patients,  which  he  has  either  feen  or  heard  of,  amounts 
in  all  to  48 ;  a  circumftance  which  proves,  that  this  complaint  has  been  frequently  overlooked, 
and  is  by  no  means  fo  rare  as  has  been  generally  fuppofed.  At  the  end  of  the  firft  part  are 
fome  experiments  and  obfervations  on  urine  and  fugar,  by  Mr.  Cruickfliank. 

In  the  fecond  part,  we  find  a  continuation  of  the  trials  of  the  nitrous  acid,  and  other  oxy- 
genating remedies,  in  the  lues  venerea;  which  appear  to  eftablifh  their  efficacy  in  this 
difcafe,  both  in  its  primary,  and  fecondai-y  ftages.  The  number  of  cafes  cured  in  this  way, 
fince  March  1797,  amount  to  155;  of  thefe,  59  were  cured  by  the  nitrous  acid;  59  by  the 
oxygenated  muriate  of  pot-afli;  7  by  the  oxygenated  muriatic  acid,  and  muriate  of  man- 
ganefe;  3  by  lemon  juice;  1 1  by  the  nitrous  and  other  acids,  combined  with  the  oxygenated 
muriate  of  pot-afli;  and  16  by  a  combination  of  mercury,  with  the  new  remedies. 

In  a  few  inftances,  where  tliefe  medicines  had  not  been  continued  for  a  fufficient  length  of 
time,  relapfes  occurred,  and  the  fecondary  fymptoms  made  their  appearance;  but  all  thefe 
were  afterwards  completely  cured,  by  perfcvering  in  the  fame  mode  of  treatment. 

At  the  conclufion  of  this  part  are  fome  ufeful  and  neceflary  obfervations,  with  re- 
gard to  the  management  of  thefe  remedies,  more  efpecially  the  oxymuriate  of  pot-a(h  :  but 
for  particulars,  the  reader  muft  refer  to  the  work  itfelf;  of  the  charafter  and  importance  of 
which,  the  public  is  fufficicntly  aware. 

Moyens  d'apprendre  a  compter  furement  et  avec  facilite,  ouvrage  pofthume  de  Con- 
dorcet ;  or.  Methods  of  learning  Accounts  with  certainty  and  eafe.  One  volume,  8vo. 
132  pages.     Sold  by  Maulardier  at  Paris,  year  vii. 

The  diftinguifhing  chara£ler  of  thefe  elements,  fays  the  editor,  are,  that  they  exhibit  the 
elements  of  arithmetic  and  logic  at  the  fame  time.  The  author  ufes  the  decimal  fyftem. 
Mag.  Encycl.  ^ 

Mr.  Lowry,  engraver,  of  Titchfield-ftreet,  the  artift  alluded  to  at  page  429  of  the  prefent 
volume,  has  fhewn  me  his  machine  for  ruling,  which  is  very  different  from  mine,  in  all  its 
parts.  As  he  has  no  adtual  divifion  in  the  part  which  produces  the  fhift,  he  can  regulate  his 
diftances  to  incommenfurate,  as  well  as  commenfurate,  meafures.  The  parallax  of  the  rul- 
ing point,  againft  which  I  had  made  no  provifion,  is,  by  a  very  fimple  and  happy  contriv- 
ance, taken  away  in  common  ruling,  or  rendered  variable  at  pleafure,  for  the  purpofe  of 
thickening  the  ftroke  in  Ihading.  This,  together  with  his  great  profelfional  (kill  and  fcience, 
has  given  Mr.  Lowry's  engravings  the  degree  of  precifion  and  efFeft  for  which  they  are  fo 
juftly  admired. 

In  July  1786, 1  communicated  to  the  celebrated  Mr.  Troughton,  of  Fleet-ftreet,  a  fmall 
apparatus,  for  fecuring  the  point  from  lateral  deviation,  in  dividing  mathematical  inftruments, 
which  I  did  not  think  neceflary  to  add  to  the  inftrument  in  plate  20. — The  execution  of  that 
plate,  in  which  the  point  wae  left  to  the  ufual  management  of  the  artift,  fhews,  however, 
that  fuch  a  contrivance  is  neceflary,  and  I  fliall  take  an  opportunity  of  defcribing  it  hereafter. 


J'liiliij.Jomimi.  Int. II.  ri.XXI.  faeiiiy  ftti/e  .iZh 

Air  Viinip  hv  the  Rev.  Jnmcj  Little. 


Fig.  i. 


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J'hiliis.  Journal .  Vol. II. I'l.. XXII.  fiiniu/J'uye  jo-t. 


A 

JOURNAL 


OF 


NATURAL   PHILOSOPHY,   CHEMISTRY, 


AND 


THE   ARTS. 


MARCH   1799. 


ARTICLE   I. 

All  Account  of  Improvements  In  EleBrkal  Batteries  t  a  Method  of  augmenting  their  Power,  nvith 
Experiments,  fieiuing  the  proportional  Lengths  of  Wirefufedby  different  ^lantities  of  EkBricityt 
and  a  Defcription  of  a  new  tiniverfal  EleSirometer.  By  Mr.  JoHN  CuTHBERTSON  *>  No. 
53,  Polandflreety  London,  1799. 

J-N  the  year  1774,  Mr.  E.  Nairne  made  an  Eledrical  Machinfe,  far  fuperior  in  afting  power 
tp  any  that  had  been  made  before*,  and  a  Battery  more  judlcioufly  conftru£ted  and  larger 
than  any  former  one,  with  which  he  made  a  number  of  interefting  experiments.  One  in  parti- 
cular, affords  an  accurate  meafure  of  the  power  of  his  battery,  compared  with  fuch  batteries 
as  have  been  made  fince  that  time.  I  mean  the  experiment  of  melting  or  difperfing  a  metal- 
lic wire.  His  battery  contained  50  fquare  feet  of  coated  furface ;  and  he  found  that  it  was 
capable  of  receiving  a  charge  fo  high,  that  the  difcharge  melted  45  inches  of  iron  wire  of 
^1^  part  of  an  inch  in  diameter,  which  anfwers  to  about  J-  of  an  inch  in  length  for  each  fquare 
foot,  which  was  the  greateft  length  of  wire  ever  melted.  We  have  no  account  of  this  experi- 
rhenthavingbeen  afterwards  repeated  on  a  fcale  of  anyconfiderablemagnitudetill  the  year  1 785  ; 
when  I  conflrufted  a  battery  for  the  Teylerian  fociety,  atHaerlem,  containing  1 35  fquare  feet  of 
coated  furface.  With  this  battery  1 80  inches  of  the  fame  fort  of  wire  was  melted,  which 
feemed  to  be  much  more  than  in  proportion  to  the  fize  of  the  battery,  as  this  was  about  1,3 
inches  for  each  fquare  foot.  This  battery  was  afterwards  increafed  to  225  fquare  feet  of 
coating,  and  with  this  300  inches  of  the  fame  fort  of  wire  melted,  which  was  alfo  at  the  rate 
of  1,3  inches  for  each  fquare  foot.  Some  time  after  this,  I  made  another  battery  for  the 
fame  fociety,  containing  550  fquare  feet  of  coating,  compofed  of  loo  jars  of  $\  fquare  feet 

*  Communicsted  by  the  author.        f  Philof.  Tranf. 

Vov.  II — March  i  799.  3  Y  each. 


§iS  £xperi*>iefits  ivItA  large  eleEirical  Batteries. 

eaci.  The  fame  fort  of  wire  was  not  tried  with  this  ;  but  it  could  be  calculated  from  other 
forts  of  wire  which  it  melted,  that  it  was  capable  of  melting  655  inches,  being  alfo  at  the 
rate  of  1,3  inch  for  each  fquarefoot.  This  increafe  of  power,  which  is  almoft  double  that 
of  Mr.  Nairne,  might  be  attributed  to  the  a£ting  power  of  tlie  maclune;  for  though  Mr. 
Nairne's  machine  poflijfled  the  (trongcfl  acling  power  of  any  machine  made  at  that  time,  yet 
It  could  not  be  fuppofed  to  poflefs  that  high  charging  property  of  the  Hacrlem  machine. 

Since  my  return  to  London,  I  have  made  feveral  batteries,  commonly  compofed  of  15  jars, 
each  containing  168  fquarc  inches  of  coated  furface,  confequently  the  whole  battery  contains 
17  fquare  feet  of  coating.     This  battery,  according  to  tiie  proportion  of  that  made  by  Mr, 
Nairne,  fliould  fufe  6,3  inches,  and  in  proportion  to  the  Haerlem  batteries,  it  ought  to  fufe 
22  inches;  but  inftead  of  following  that  proportion,  it  is  found  to  fufe  60  Inches,  which  is  an 
aftonifliing  increafe  of  force.    For  the  battery  isonlyabout  one-third  part  of  that  of  Mr.  Nairne, 
and  fufes  a  much  greater  length  of  wire ;  and  though  it  is  only  -/^  part  of  that  at  Haerlem, 
yet  it  fufes  t'o  of  the  length  of  wire.     It  feems  difficult  at  firfl;  fight  to  account  for  this  advan- 
tage.    I  have  before  remarked,  that  the  proportional  difference  between  the  charge  of  the 
battery  at  Haerlem  and  Mr.  Nairne' s,  might  be  accounted  for,  from  the  high  charging  power 
of  the  great  machine  5  but  the  refult  of  the  laft-mentioned  experiments  overturns  that  notion  j 
as  it  can  by  no  means  be  fuppofed,  that  a  fingle  2-feet  plate  machine,  which  I  have  ufed  to 
charge  the  battery  of  1 7  fquare  feet  fo  high  as  to  fufe  60  inches,  can  have  a  higher  charging 
poW^er  tlian  that  at  Haerlem  ;  fo  that  it  mufl  proceed  from  fome  other  caufe.     It  might  be 
queftioned  whether  all  thebatteries  were  alike  judicioufly  conftru£led.   A-s  to  Mr.  Nairne's,  it 
had  certainly  faults,  both  with  refpeft  to  the  coating  aftd  the  mounting  of  the  jars ;  but  the 
batteries  at  Haerlem  were  as  judicioufly  conftrudled  as  my  prefent  one,  which  I  am  fpeaking 
of,  and  which  exceeds  them  in  fuch  an  aftonifliing  degree  in  its  proportional  force.     The  only 
difference  between  my  prefent  batteries  and  thefe  at  Haerlem  is  in  the  glafs.  They  were  coni- 
poifed  of  glafs,  blown  in  Bohemia,  and  thofe  which  I  make  here  are  of  white  flint-glafs.     I 
mention  this  faft,  but  I  am  not  inclined  to  think  that  the  caufe  of  the  difference  depends  on 
the  glafs,  becaufe  I  remember  to  have  melted  the  fame  quantity  of  wire  with  one  jar  of  that 
kind  of  glafs  when  in  Amfterdam,  as  I  do  at  prefent  with  white  flint-glafs  ;  fo  that  it  only 
remains  now  to  be  fought  for  ip  the  manner  of  ufing  or  charging  each  battery,  and  here  we 
fhall  probably  find  a  means  of  folving  this  paradox. 

With  regard  to  the  batteries  at  Haerlem,  they  were  never  attempted  to  be  charged  but  in 
dry  weather,  being  fuch  as  was  then  commonly  called  favourable  for  eleftrical  experiments. 
TJiere  was  no  convenience  in  the  room  where  the  machine  and  batteries  were  ufed,  for  making 
a  fire,  which  was  therefore  ill  calculated  for  eleftrical  experiments  :  the  batteries  previous  to 
charging,  were  made  as  clean  and  dry  as  poffible ;  and  if  they  received  a  charge  fo  high  as  to 
caufe  a  fpontaneous  explofion,  they  were  then  looked  upon  to  be  in  their  moft  favourable  ftate. 
It  was  about  thistime  that  we  were  told  by  Mr.  Brooke,  that  a  coated  jar  would  take  a  higher 
charge  when  dirty,  than  when  clean ;  but  the  degree  of  dirtynefs  was  fo  ill  defined,  that 
I  muft  own  I  never  could  dirty  a  fingle  jar  fo  as  to  anfwer,  or  to  come  near  what  was  faid  of 
it;  and  to  pretend  to  bring  all  the  jars  in  a  large  battery,  containing  upwards  of  two  hundred, 
iirto  that  ftate  of  dirtynefs  was  never  attempted  ;  neither  dees  it  appear  that  Mr.  Brooke  ever 

t}iought 


Method  ef  encrenfing  the  Pottirr  »f  ek^rkal  Batterni.  5^7 

^thought  of  dirtying  his   battery  jars,  as  he  only  mentions  trying  two  fmall  bottles,  wHofc 
charging  property  was  very  differently  increafed  by  his  method  of  dirtying. 

Some  time  afterwards,  in  the  year  1792, 1  happened  cafually  to  difeover  that  a  coated  jaf, 
when  it  was  a  little  dampiih  in  the  infide  above  the  coating  {which  is  always  the  cafe  when  a 
jar  isfrefli coated),  would  take  a  higher  charge  than  it  would  do  after  it  had  been  coated  for  foma 
time,  and  was  quite  dry  in  the  infide ;  and  alfo,  if  tlie  atmofphere  was  in  a  moid  ftate,  and 
the  jar  not  dryed  in  the  infide,  it  would  take  an  equally  high  charge.  From  this  it  appeared 
evident  to  me,  that  if  I  could,  by  any  means,  render  the  infide  of  jars  damp,  it  would  anfwer 
the  fame  purpofe.  Breathing  into  a  jar  was  trysd,  and  the  fucccfs  was  fuch,  that  it  would  re- 
ceive an<l  retain  nearly  double  the  quantity  of  electric  fluid  it  could  retain  when  dry  ;  and  in 
trying  to  fufe  wire  with  the  charge  of  one  jar  in  a  dry  flate»  no  more  than  5  inches  ceuld  bc 
fufed,  though  after  breathing  into  it,  i  %  inches  were  fufcd. 

This  method  appeared  at  firfk.  fight  to  have  increafed  the  force  to  more  than  double  ;  but 
notwithftanding  fo  evident  and  Itr'iking  an  effetl:,  I  did  not  think  of  trying  what  would  bc 
the  refult  of  charging  a  battery,  after  the  jars  had  been  breathed  into ;  being  deterred,  as  I 
fiippofe,  from  the  idea  of  its  being  fo  contradictory  to  the  common  method  of  ufmg  battcriesj 
which  was  never  attempted  to  be  done,  but  when  the  atmofphere  was  in  a  tolerably  dry  Hate, 
and  the  jars  previoufly  cleaned.  But  in  March  1 796,  being  engaged  in  a  courfe  of  experiments, 
when  the  atmofphere  was  fo  very  dry,  that  a  fpontancous  difcharge  always  took  place  before 
J  had  a  fuiEcient  force  to  anfwer  my  purpofe,  it  then  occurred  to  me  to  try  what  the  cffeft 
of  breathing  into  the  jars  of  the  battery  would  be.  In  this  trial,  or  refearch,  it  became  ne- 
ceflary  firil,  to  afcertain  the  real  charge  that  the  battery  was  capable  of  receiving,  before  i 
voluntary  explofion  took  place.  This  battery  contained  1 7  fquare  feet  of  coated  glafs,  and 
was  compofed  of  15  jars:  it  was  found  in  the  then  ftate  of  the  atmofphere  to  be  incapable  of 
fufing  a  greater  length  of  wire  than  18  inches.  But  after  breathing  into  each  jar  through  a 
glafs  tube,  it  took  a  charge  Ns'hich  fufed  60  inches,  to  my  very  great  furprife  and  fatisfaftion, 
as  I  then  thought  I  had  obtained  a  method  of  making  one  battery  perform  the  fundtlon  of 
three ;  becaufe  three  times  the  quantity  of  wire  was  fufed,  as  Appears  by  comparing  this 
■with  what  had  been  performed,  by  increa  fing  the  furface  of  batteries  by  former  electricians. 
This  notion  fecmed  to  be  juftified,  by  obfcrving  in  Dr.  van  Marum's  works,  that  I  had  en«> 
larged  his  batteries  at  three  different  times  ;  his  firft  contained  135  fquare  feet  coating,  tlic 
fecond  225  fquare  feet,  and  the  third  550  ;  and  the  higheft  charge  of  the  firft  was  juft  fuf- 
ficient  to  fufe  180  inches  of  iron  wire  of  tto  of  an  inch  diameter,  or  6  inches  of  iron 
wire  of  ^'^  of  an  inch  diameter ;  the  higheft  charge  of  the  fecond  fufed  300  inches  of  the  firft- 
inentloned  wire,  or  10  inches  of  the  laft-mentloned;  the  higheft  charge  of  the  third  fufed  25 
inches.  We  find  that  thefe  batteries  increafed  in  power  in  the  fame  proportion  as  the  coated 
furface  was  increafed.  I  was  prcfent  when  the  wire  v.-as  fufed  by  the  two  f.rft-n\entioned 
^J»5rtteries,  but  at  the  third  not  •,  ho^vever,  we  have  no  reafon  to  doubt  Dr.  van  Marum's  re- 
port. Thefe  experiments  fupported  me  in  my  firft  notion,  that  I  had  difcovered  a  new 
method  of  increafing  the  force  of  a  battery  to  three  times  its  ufual  power  ;  but  being  unable 
to  account  for  it  to  my  own  fatisfa£lion,  I  refolved  to  make  a  tourfe  of  experiments,  in  order 
to  throw  fomc  light  on  the  fubject. 

3  Y  a  Tke 


■  5*8  Dffcription  of  a  new  univiyfal  EleByometer, 

The  chief  experiments  which  have  been  made  on  the  force  of  batteries,  by  Mr.  Brooke*, 
at  Norwich,  in  the  year  1786,  and  by  Dr.  Van  Marum,  in  1785  and  1795.  The  refults 
were  very  different.  Some  experiments  which  I  made  in  Holland,  and  afterwards  repeated 
here,  did  not  feem  to  confirm  either  of  the  two.  All  that  had  been  done  either  by  Dr.  van 
Marum,  or  myfelf,  was  done  without  the  help  of  fuch  an  eleflrometer  as  could  indicate 
the  proportional  quantities  of  electric  fluid  with  a  fufficient  degree  of  accuracy. 

Mr.  Brooke  was  poffefled  of  an  inftrument  of  his  own  invention,  with  which  it  was  pof- 
fihle  to  afcertain  the  comparative  flrength,  if  managed  with  the  lame  dexterity  as  Mr.  Brooke 
himfelf  poffefles.  But  this  inftrument  came  fo  high  in  price,  and  was  fo  very  difficult  in  its 
ufe,  that  few  eleftricians  provided  themfelves  with  it ;  which,  perhaps,  is  one  reafon,  why 
this  fubjeft  has  fo  long  remained  in  obfcurity.  I  have  lately  had  the  good  fortune  to  invent 
an  ele£trometer  which  has  all  the  properties  that  fuch  experiments  require,  and  is  very  fira- 
ple  and  eafy  in  its  ufe  ;  and  with  this  I  found  myfelf  enabled  to  go  through  fuch  experiments 
as  were  neceffary,  with  greater  accuracy  than  any  which  had  been  made  before. 
Tlie  eledrometer  is  reprefented  in  PL  xxiii.  G  H  is  a  long  fquare  piece  of  wood,  about  1 8 

finches  long,  and  fix  inches  bi-oad,  in  which  are  fixed  three  glafs  fupports,  D  E  F,  mounted  with 
brafs  balls,  a  b  c.  Under  the  brafs  ball  a,  is  a  long  brafs  hook  ;  the  ball  c  is  made  of  two 
hemifpheres,  the  under  one  being  fixed  to  the  brafs  mounting,  and  the  upper  turned  v/ith  a 

-groove  to  Ihut  upon  it,  fo  that  it  can  be  taken  off  at  pleafure.  The  ball  b  has  a  brafs  tube 
fixed  to  it,  about  three  inches  long,  cemented  on  to  the  top  of  F,  and  the  fame  ball  has  a 
hole  at  the  top,  of  about  one-half  inch  diameter,  correfponding  with  the  infide  of  the  tube. 
A  B  is  a  ftraight  brafs  wire,  with  a  knife-edged  centre  in  the  middle,  placed  a  little  below 
the  centre  of  gravity,  and  equally  balanced  with  a  hollow  brafs  ball  at  each  end,  the  centre, 
or  axis,  refting  upon  a  proper  fhaped  piece  of  brafs  fixed  in  the  infide  of  the  ball  c ;  that  fide 
of  the  hemifphere  towards  c  is  cut  open,  to  permit  the  end  ^  A  of  the  balance  to  defcend 
till  it  touches  the  ball  a,  and  the  upper  hemifphere  C  is  alfo  cut  open  to  permit  the  end  c  B 
to  afcend ;  i  is  a  weight,  weighing  a  certain  number  of  grains,  and  made  in  the  form  of  a  pin 
with  a  broad  head  -,  the  ball  B  has  two  holes,  one  at  the  top,  and  the  other  at  the  bottom  ; 
the  upper  hole  is  fo  wide,  as  to  let  the  head  of  the  pin  pafs  through  it,  but  to  ftop  at  the 
under  one,  with  its  fhank  hanging  freely  in  ^ ;  a  number  of  fuch  pins  are  commonly  made 
to  each  eleftrometer  of  different  weights  5  ^  is  a  common  Henley's  quadrant  eledlrometer, 
and  when  in  ufe,  it  is  fcrewed  upon  the  top  of  c. 

It  is  evident  from  the  conftrudlion,  that  if  the  foot  ftand  horizontal,  and  the  ball  B  be 
made  to  touch  b,  it  will  remain  in  that  pofition  without  the  help  of  the  weight  / ;  and  if  it 

»  Though  I  had  read  Mr.  Brooke's  book,  as  I  thoughr,  with  a  fufficient  degree  of  attention  when  it  was 
firft  publilhed,  I  did  not,  till  lately,  obferve  that  it  contained  any  experiments  relating  to  this  fubje6t,  till  I 
begun  to  write  this  paper,  and  had  occafion  to  look  into  his  book  for  fome  references.  I  believe  thefc 
experiments  had  efcapcd  Dr.  van  Marum's  notice  likewife,  as  I  never  heard  him  fpeak  of  them  when  he  was 
making  others  of  the  fame  kind.  Though  Mr.  Brooke's  experiments  were  conduced  with  much  fkill  and  in- 
telligence, they  are  fo  confufedly  arranged,  that  this  had  entirely  efcapcd  my  notice  ;  and  I  doubt  not  but 
that  it  liad  alfo  efcapcd  the  notice  of  (tvcral  other  ele£lri(;ians, 

iliould 


J^evj  univerfal  Ele^rometey,  5,29 

{Tiould  by  any  means  receive  a  very  low  charge  of  ele£tric  fluid,  the  two  balls  b,  B,  will  repel 
each  other;  B  will  begin  to  afcend,  and,  on  account  of  the  centre  of  gravity  being  above 
the  centre  of  motion,  the  afcenfion  will  contiuue  till  A  reft  upon  a.  If  the  balance  be  fet 
again  horizontal,  and  a  pin  7,  of  any  fmall  weight,  be  put  into  its  place  in  B,  it  will 
caufe  B  to  reft  upon  b,  with  a  preflure  equal  to  that  weight,  fo  that  more  eletflric  fluid  muft 
be  communicated  than  before,  before  the  balls  will  feparate;  and  as  the  weight  in  B  is  in- 
creafed  or  diminiflied,  a  greater  or  lefs  quantity  of  eleftric  fluid  will  be  required  to  efFedl  a 
feparation; 

When  this  inftrument  is  to  be  applied  to  a  jar,  or  battery,  for  which  purpofe  it  was  in- 
vented, one  end  of  a  wire,  L,  muft  be  inferted  into  a  hole  in  b,  and  the  other  end. into  a  hole 
of  any  ball  proceeding  from  the  infide  of  a  battery,  as  M  *  :  k  muft  be  fcrewed  upon  c,  with 
itsindex  towards  A-,  the  reafon  of  this  inftrument  being  added,  is  to  fliew,  by  the  index  con- 
tinuing to  rife,  that  the  charge  of  the  battery  is  increafing,  becaufe  the  other  part  of  the  in-- 
ftrument  does  not  adl  till  the  battery  has  received  its  reqiiired  charge- 

If  this  inftrument  be  examined  with  attention,,  it  will  be  found  to  confift  of  three  elcGro-- 
meters;  and  anfwers  three  different  purpofes,.  namely,  a  Henly's  ele£trometer,  Lane's  dif- 
charging  electrometer,  and  Brooke's  fteelyard  eledlrometer;  the  firft  not  improved,' but  the  two 
laft,  which  were  very  defedive  when  firft  invented,  I  flatter  myfelf  are  here  brought  to  per- 
fection. As  the  only  ufe  of  Henley's  eledlrometer  to  this  inftrument  is,  as  I  have  faid  before 
to  ftiew,  by  its  continuing  to  increafe  in  divergency,  that  the  battery  continues  to  receive  a 
ftill  ftronger  charge,  it  required  no  improvement ;  but  Lane's  electrometer,  in  its  primitive 
ftate,  could  by  no  means  anfwer  the  required  purpofe  for  batteries,  becaufe  the  ball  intended 
to  difcharge  the  battery,  was  neceflliirily  placed  fo  near  to  the  ball  of  the  battery,  that  duft  and. 
fibrous  particles  were  always  attraCted  by  and  adhered  between  the  two  balls,  fo  as  to  retard 
the  charging,  and  often  render  a  high  charge  impoflible  :  whereas,  in  this,  they  are  placed  at 
four  inches  afunder ;  and  when  the  defired  height  of  charge  is  obtained,  and  not  before,  the 
ball  of  the  eleCtrometer  moves  of  itfelf  nearer  to  the  ball  which  is  connecSted  with  the  outfidc 
of  the  battery,  and  caufes  a  difcharge.  The  defeats  in  Brooke's  fteelyard  eledrometer  were, 
ift,  that  it  could  not  caufe  a  difcharge,  and  adly,  the  difficulty  of  obferving  the  firft  feparation 
of  the  balls  caufed  great  error.  If  it  were  not  placed  in  an  advantageous  light  (which  the 
nature  of  the  experiments  could  not  always  permit),  it  would  not  be  feen,  without  the  at-;- 
tention  of  an  afliftant,  which  is  fometimes  unpleafant,  and  cannot  always  be  commanded.  But. 
the  inftrument  which  I  have  defcribed,  requires  no  attention  or  affiftance;  for  as  foon  as  the 
feparation  takes  place  between  B  and  b,  the  ball  A  defcends,  and  difcharges  the  battery  of 
itfelf. 

By  this  combination  and  improvements,  we  poflefs  in  the  prefent  inftrument 'all  that  can 
ever  be  required  of  an  eledrometcr ;  namely,  by  k,  we  fee  the  progrefs  of  the  charge ;  by  the 
feparation  of  B,  b,  we  have  the  repulfive  power  in  weight ;  and  by  the  ball  A,  the  difcharge 
is  caufed,  when  the  charge  has  acquired  the  ftrength  propofed.  / 

*  A  chain,  or  wire,  or  any  body  through  which  the  charge  is  to  pafs,  muft  be  hung  to  the  hook  at  m, 
and  carried  from  thence  to  the  outfide  of  the  battery,  as  is  rcprefcnted  by  the  line  N. 

Experiments 


53»  Tixpfrmeists  w  eleSfric  Jtrs  stiiJ  Batttriet. 

J^xj:{r'i7nintj  made  wiih  a  Vii^w  to  determine  in  what  Degrre  the  charging  Capacity  ef  coated  Jart 
is  increafed  by  ireathifig  into  ihcin  before  ihe  charging. 

Experiment  I.  Prepare  the  e!e£lrometer  in  the  manner  fliewn  in  the  plate,  with  f!ie  jar  M 
annexed,  which  contains  about  i68  fqtiare  inches  of  coating*;  put  into  B  the  pin,  marked 
15  ;  take  two  inches  cf  watch-pendulum  wire,  fix  to  each  end  a  pair  of  fpring  tongs,  as  is  rc- 
.prefcnted  at  G  m,  hook  one  end  to  m,  and  the  other  to  the  wire  N,  communicating  with  the 
outfide  of  the  jar ;  let  the  uncoated  part  of  the  jar  be  made  very  clean  and  dry ;  and  let  the 
-prime  conductor  of  an  eledtrical  machine,  or  a  wire  proceeding  from  it,  touch  the  wire  L ; 
then  if  the  machine  be  put  in  motion,  the  jar  and  eledtrometer  will  ^charge,  a -,  will  be  feen 
iy  the  rifing  of  the  index  of  k,  and  when  charged  high  enough,  B  will  be  repelled  by  by  and 
A  will  dcfcend  and  difcharge  the  jar  through  the  wire,  which  wa«  confined  in  the  tongs, 
and  the  wire  will  be  fufed  and  run  into  balls. 

Experiment  2.  Put  into  the  tongs  eight  inches  of  the  fame  fort  of  wire  as  before,  hang  one 
•pair  of  tongs  to  the  hook  m,  and  apply  the  otherto  the  wire  \vhich  forms  the  outfide  communis 
cation :  take  out  the  pin  in  B,  and  put  in  its  ftcad  one  marked  30 ;  all  the  other  part  of  the 
apparatus  remaining  as  before,  and  the  uncoated  part  of  the  jar  being  previoudy  cleaned  and 
dried ;  the  machine  being  then  put  in  motion,  the  jar  and  eleiElrometer  will  charge,  as  is 
ihewn  by  the  rifmg  of  the  ind^  as  before ;  bet  as  foon  as  the  jar  has  received  a  greater  quan- 
tity of  eleftric  fluid  than  before,  a  fpontaneous  explofion  will  happen  without  affecting  the 
balls  B  bf  becaufe  the  difcharge  will  have  pafled  along  the  uncoated  part  of  the  jar  from  the 
Infide  coating  to  the  outfide :  ^vhence  it  follows,  that  while  the  jar  remains  in  that  clean 
ftate,  it  is  incapable  of  receiving  a  charge  high  enough  to  affect  the  balls,  or  even  a  higher 
charge  than  Lt  had  received  in  the  firfl  experiment.  I^et  the  uncoated  part  of  the  jar  be 
therefore  rendered,  in  a  flight  degree,  damp;  which  is  eafily  done,  by  breathing  into  the  in- 
fide, through  a  glafs  tube ;  put  the  machine  in  motion,  and  no  fpontaneous  explofion  will 
happen,  but  the  balls  B  b  will  repel,  as  in  the  firfl;  experiment,  and  the  difcharge  will  happen 
from  A  to  a,  and  pafs  through  the  wire  placed  in  the  circuit;  and  though  it  was  eight  inches, 
it  will  be  fufed  in  the  fame  degree  as  two  inches  in  th'e  laft  experiment,  namely,  the  wire 
feen  red  hot  the  -whole  length,  and  then  fall  into  balls. 

Very  different  degrees  of  fufion  are  caufed  by  ele(?bric  difclvarges,  which  may  caufe  grent 
jmiflakes,  if  not  well  attended  to.  It  is  proper  to  adhere  to  the  degree  above-mentioned, 
and  particular  care  ought  to  be  taken  to  lay  the  \vire,  intended  for  fufion,  ftraight,  without 
any  bendings  or  angles  in  it.  The  wire  ufed  in  the  two  laft  experiments,  was  that  which  is 
commonly  called  watch-pendulum  wire,  which  is  flatted  ;  and  as  it  approaches  very  near  to 
fucha  fliarp  edge  as  might  be  fuppofed  to  affcftthe  experiment,  by  permitting  a  difiipation  oi 
die  electric  fluid  in  its  paflage,  round  wires  were  tried,  a-nd  the  refult  was  the  fame. 

*  Tike  out  the  p'n  'u  B,  ani  obfe.vt  whether  tl.e  ball  B  will  remain  at  reft  upon  1/  j  if  •ot,  Mwn  the  «d- 
jiifting  'crew  atC,  till  it  jull  reiiains  upoa  A. 

By 


On  the  Power  ef  tleSrle  Jars  and  Batterifi.  5^31 

By  tlic  laft  experiment  it  appears,  that  breathing  into  the  jar  had  increafcd  its  charging  ca- 
pacity nearly  in  the  fame  proportion  as  it  had  done  the  batteries :  after  breathing,  it  received 
a  charge  fufficient  to  fufe  four  times  the  length  of  wire  it  did  when  clean;  but  by  the  weight  In 
the  eleftrometer,  and  alfo  by  thS  greater  number  of  revolutions  given  before  the  difcharge 
happened,  it  might  be  fuppofed  that  the  jar  had  received  only  a  double  charge. 

The  following  experiments  are  intended  to  flicw  the  lengths  of  wire,  which  are  juft  fufcd. 
by  various  quantities  of  eledric  fluid  at  the  fame  intenfity. 

Experiment  3.  For  this  purpofe,  a  fecond  jar  was  placed  at  the  wire  L,  the  pin  marked- 
30  was  taken  out,  and  15  put  in  Its  place,  two  inches  of  the  fame  fort  of  wire  as  ufed  in  the 
laft  experiment  was  placed  in  the  circuit,  every  other  part  of  the  apparatus  remaining  un- 
altered ;  the  machine  was  tlien  put  in  motion,  till  B  begun  to  afcend,  when  it  was  flopped,, 
and  before  A  could  reach  «,  one  of  the  jars  was  puflied  from  the  wire  L  (to  do  which,  there 
is  always  fufEcient  time  while  the  eleftrometer  is  in  motion),  the  difcharge  was  efFeiied,  ani 
the  two  inches  of  wire  was  juft  fufed. 

Experiment  4.  The  jar  which  was  pufhed  away  in  the  laft  experiment  was  difcharged,  anc^ 
placed  at  the  wire  L,  as  before,  and  eight  Inches  of  the  fame  fort  of  wire  placed  In  the  circuit ;; 
the  outfide  coating  of  the  jars  either  touched  each  other,  or  had  a  metallic  communication. 
All  the  other  part  of  the  apparatus  remained  as  before,  and  the  machine  was  put  in  motion^ 
tiU  B  begun  to  afcend  ;  the  jar  was  not  resioved,  as  In  the  laft  experiment,,  but  fufFered  to 
difcharge  witli  the  other,  and  the  eight  inches  of  wire  was  fufed  in  the  fame  degree  as  the 
two  inches  in  the  laft  experiments. 

It  is  evident  from  the  pofition  of  the  apparatus,  that  the  quantity  of  eleflrk  fluid  difcharged 
in  the  laft  experiment  muft  be  double  that  of  the  former  j  yet,  In  repeating  the  experiment, 
I  had  different  refults,  which  made  me  again  fufpe£l  the  edges  of  the  wire,  I  therefore  re- 
folred  to  take  round  wire,  and  of  as  large  a  diameter  as  could  be  conveniently  fufed. 

Experiment  5,  ivith  three  jars.  Iron  vidre  of  t|^  part  of  an  inch  in  diameter,  and  fix  inches 
in  length,  was  placed  in  the  circuit  -,  three  jars  were  placed  fo  that  the  balls  proceeding  from 
their  infides  touched  the  wire  L,  and  their  outfide  coatings  touched  each  other.  The  machine 
■was  turned  till  B  begun  to  afcend,  tlie  difcharge  was  caufed,  and  the  whole  length  of  the  wire 
was  juft  run  into  balls. 

Experiment  6y  with  three  jurs,  one  renvnted.  Two  inches  of  the  fame  fort  of  wire  was 
placed  in  the  circuit  In  the  fame  manner  as  the  laft,  and  the  three  jars  remained  ;  the  ma- 
chine was  turned  till  B  begun  to  afcend,  tlien  one  of  the  jars  was  drawn  away,  confequently 
f)nly  two  difcharged,  and  the  wire  juft  run  into  balls  as  the  laft. 

Experiment  7,  -with  four  jars.  Wire  of  tto  part  of  an  inch  was  taken,  and  four  jars  placed 
in  contafl:  with  the  wire  L,  with  their  outfide  coatings  in  contacl:  with  each  other,  and  eight 
inches  of  wire  was  placed  In  the  circuit ;  the  weight  in  the  electrometer  remained  as  before  ; . 
the  machine  was  then  put  in  motion  till  B  begun  to  afcend,  the  difcharge  was  efFe£ted,  and 
the  wire  was  fufed,  and  run  into  balls.  The  experiment  was  repeated  with  the  fame  fort  of 
wire  8i  inches  long ;  the  difcharge  was  juft  fufRcIent  to  run  it  into  balls. 

Repeated  with  nine  inches  of  the  fame  fort  of  wire,  and  the  difcharge  caufed  it  to  be  red 
hot  the  whole  length. 

Experiment- 


532  ,      0«  the  PciviT  of  eleBrlcal  Batteries. 

Experiment  8,  with  four  jars,  two  removed.  Two  inches  of  the  fame  fort  of  wu'C  was  placed 
In  the  circuit,  all  the  jars  remaining  as  in  the  laft  experiment,  the  machine  put  in  motion, 
till  B  begun  to  afcend,  then  two  of  the  jars  were  drawn  away ;  the  difcharge  was  caufed, 
and  the  wire  was  fufed,  and  run  into  balls. 

Repeated  with  the  fame  fort  of  wire  i\  inches  long,  the  difcharge  caufed  it  to  be  red  hot 
the  whole  length. 

Experiment  9,  tulth  fourteen  jars.  Wire  of  to^  part  of  an  inch  diameter  was  taken,  eight 
inches  long,  and  proceeded  according  to  Experiment  7  ;  ,it  was  fufed  and  run  into  balls. 

Experiment  lo,  ■with  fourteen  jars,  feven  ranoved.  Two  inches  of  the  fame  fort  of  wire  was 
■taken,  and  proceeded  with,  according  to  Experiment  8  j  it  was  fufed  and  run  into  balls. 

The  refult  of  the  foregoing  experiments  proves  fufhciently,  that  double  quantities  of  elec- 
tric fluid,  in  the  form  of  a  difcharge,  will  melt  four  times  the  length  of  wire  of  a  certain  dia- 
meter; and  Experiments  5  and  6  prove  that  when  one-third  part  is  added  to  two,  three  times 
the  length  of  wire  was  fufed. 

Thefe  experiments  give  reafon  to  apprehend  fome  error  in  Dr.  van  Marum's  experiments, 
becaufe  he  found  his  batteries  to  increafe  in  power  only  in  the  fame  proportion  as  the  coated 
furface  was  increafed,  viz.  that  double  furface  of  coated  glafs  only  could  fufe  double  lengths 
of  wire  of  the  fame  diameter. 

The  doctor  might,  perhaps,  have  "been  led  into  a  miftake  in  the  following  manner :  firft,  he 
rnay  not  have  charged  the  batteries  to  an  equal  height,  £s  he  did  not,  at  that  time,  poflefs  an 
electrometer  of  fuilicient  accuracy  for  that  purpofe ;  and,  fecondly,  he  may  not  have  been 
aware  -of  the  different  degrees  of  fufion  caufed  by  eleftric  difchargeSj  but  only  judged  of  the 
force  by  the  wires  being  converted  into  balls ;  by  which  great  miftakes  may  happen.  For 
if  a  wire  be  taken  i  S  inches  long,  and  of  fuch  a  diameter,  that  when  a  jar  or  battery  is 
charged  to  fuch  a  height  as  juft  to  caufe  it  to  run  into  balls,  much  fliorter  lengths  of  that 
fame  fort  of  wire  may  be  fubje^bed  to  the  fame  force,  and  ftill  be  only  converted  into  balls  by 
it ;  eveii  if  only  feven  inches  were  taken,  nothing  but  bidls  will  appear ;  the  only  difference 
will  be,  that  the  balls  will  be  fmaller,  and  difperfed  to  a  greater  dillance,  which  might  be  ea- 
fily  overlooked.  If  fix  inche*  of  the  fame  fort  of  wire  be  taken,  it  will  be  converted  into 
balls  and  flocculi,  or  brown  oxyde  of  iron  -,  fo  that  to  be  accurate  in  this  point,  the  loweft 
degree  of  fufion  mull  be  had,  which  is  known  when  the  charge  has  pafled,  by  the  wire  being 
f-een  red-hot  the  whole  length,  and  afterwards  run  into  balls. 

Having  now  fufficiently  proved  by  experiment,  in  what  proportion  different  quantities  of 
eledtric  fluid  act  upon  different  lengths  of  wire,  which  was  required  to  be  known,  in  order 
to  explain  in  what  proportion  the  charging  capacity  of  a  jar  or  battery  is  incrcafcd  by  breath- 
ing into  it,  before  the  charging  begins,  I  Hiall  proceed  in  the  next  place  to  explain  this  point. 
The  opinion  that  I  had  at  firft  entertained  (though  fupported  by  Dr.  van  Marum's  experi- 
ments), that  I  had  found  out  a  method  of  increafing  the  charging  capacity  of  batteries  to 
three  times  thairufual  farce,  was  not  fupported  by  the  fa£ts  that  the  ufual  power  of  a  clean  and 
dry  battery,  containing  17  fquare  feet  coated  furface,  namely,  that  of  fufing  from  18  to  2Z 
inches  of  iron  wire  of  -^'^^  part  of  an  inch  in  diameto",  will  be  increafed  by  breathing  into 
tliejar,  fo  as  to  become  capable  of  fufing  60  inches.     If  the  firft-mcntioned  effed  be  taken  at 

a  mean 


Explanation  ef  the  Effecl  of  hreathing  into  EleB/ic  Jars.  533 

a  mean,  it  will  be  20,  then  the  increafed  efFeft,  gained  by  breathing,  will  be  juft  |,  as  deter- 
mined by  the  wire ;  and  experiments  5  and  6  prove,  that  in  order  to  produce  fuch  an  increafed 
efFeft,  an  addition  of  4  part  of  the  coated  furface  mull  be  added  to  the  battery,  which  is  about 
816  fquare  inches.  This  would  amount  to  an  addition  of  54  fquare  inches  to  each  jar ;  or,  in 
other  words,  if  that  quantity  of  coating  could  be  added  to  each  jar,  the  fame  effeft  would 
be  produced  as  when  breathed  into.  But  this  would  require  the  coating  to  be  within  an  inch 
of  tlie  top,  which  would  render  the  battery  unchargeable,  at  leaft,  to  that  degree.  A  battery 
©f  15  jars  conflruGed  in  tlie  ufual  manner,  will,  therefore,  by  this  treatment,  become  equiva- 
lant  in  power  to  21  jars  of  the  fame  kind,  if  clean  and  dry. 

To  explain  the  eifefl:  of  breathing  into  the  jars,  appears  to  be  a  matter  of  feme  difficulty. 
This  experiment  has  been  ftiewn  to  feveral  eleftricians,  and  different  opinions  have  been  ad- 
vanced, moft  of  which  feem  to  imply,  that  breathing  a<3:s  as  a  coating  to  the  uncoated  part, 
which  will  appear  in  the  fequel  to  be  abfurd.  Mr.  Nicholfon's  opinion  (fee  Philof.  Journal, 
II.  219)  comes  much  nearer  to  the  truth,  though  it  does  not  appear  to  me  to  be  fufScient  to 
account  for  the  efFeft  produced.  I  admit,  with  hinij  that  a  fpontaneous  explofion  over  the 
uncoated  part  is  moft  commonly  caufed  by  undulation;  but  that  this  undiflation  is  caufed 
by  the  difcharging  of  different  charged  zones,  will  be  difficult  to  prove,  becaufe  fuch  zones 
cannot  exift  upon  clean  and  dry  glafs. 

When  the  uncoated  part  of  a  Leyden  jar  is  made  perfedly  clean  and  dry,  and  the  jar  fct 
to  the  conduftor  of  a  machine  in  aftion,  it  will  begin  to  charge,  and,  while  charging,  the 
coated  part  of  the  jar,  and  the  wire  which  is  connected  with  it,  become  equally  charged,  and 
each  endeavours  to  throw  off  that  furplus  of  eledlric  fluid  which  is  forcing  into  them  5  .the' 
coating  from  its  edges  upwards,  and  that  part  of  the  wire  which  is  above  the  coating  and 
within  the  jar,  will  endeavour  to  throw  it  in  all  dire£tions,  which  will  caufe  it  to  be  furround- 
ed  by  an  eleftric  atmofphcre,  increafing  in  denfity  as  the  charge  increafes.  This  atmofphere, 
together  with  that  given  out  by  the  coating,  fills  the  whole  jar.  Part  of  the  eledtric  fluid 
forced  Into  the  coating  enters  the  furface  of  the  glafs,  but  the  uncoated  part,  being  clean  and 
dry,  both  withinfide  and  without,  the  infide  refifts  the  fluids  entering  its  furface,  which  is 
kept  fufpended  at  a  diftance,"becaufe  the  natural  eleftric  fluid  contained  on  the  outfide,  finds 
no  means  of  efcape.  But  the  aftion  of  the  machine  ftill  continuing,  prefTes  it  ftill  clofer  to 
the  furface,  and  at  laft  overcomes  that  refifting  force,  and  fome  of  the  particles  on  the  outfide 
give  way,  which  caufes  an  undulation  In  the  infide,  and  the  eleftric  fluid  clofes  inftantly  ia 
upon  its  infide  furface,  and  forces  a  greater  quantity  from  the  outfide.  Flafhes,  or  coruf- 
cations,are  thus  caufed,  which  are  always  feen  when  a  jar  Is  charging  in  the  abovementioned 
circumftances :  the  charge  ftill  continuing  to  be  made,  forces  another  quantity  from  another 
part  of  the  outfide  of  the  jar,  and  caufes  a  fecond  corufcatlon  and  undulation,  which  may 
be  fo  ftrong  as  to  caufe  a  fpontaneous  difcharge ;  or  two  or  three  more  corufcations  and 
undulations  may  happen,  before  the  difcharge,  according  to  the  fteadinefs  or  unfteadinefs  of 
the  action  of  the  machine,  the  quantity  of  eleftric  fluid  thrown  ofi^  from  the  outfide  at  each 
undulation,  and  alfo  the  degree  of  drynefs  and  cleannefs  of  the  uncoated  part  of  the  jar.  A 
difcharge  fometimes  happens  without  having  previoufly  occafioned  any  perceptible  corufca- 
tion.  This  is  the  cafe  when  the  firft  undulation  has  been  fo  ftrong,  as  to  caufe  the  whole 
Vot.  II.— March  1799.  3  Z  difcharge 


534  Bicplanatkn  of  the  EffeB  of  hreathiug  ittto  EUBrk  Jays. 

difcharge  with  the  firft  corufcation,  the  one  being  fo  quickly  followed  by  the  other  that  it  is 
imperceptible. 

A.jar  will  fometimes,  while  it  is  charging,  give  a  great  many  fmall  corufcations,  quickly 
fuccecding  each  other,  which  afterwards  ceafe  without  having  caufed  a  fpontancous  explofion^ 
though  the  aft  ion  of  the  machine  be  continued.  This  happens  when  the  uncoated  part  is 
nearly  clean  and  dry,  but  not  perfectly  fo ;  its  furface  ftill  containing  fome  conducing  par- 
ticles, but  not  fo  connefted,  that  the  eleftric  fluid  can  pafs  from  one  to  the  other  without 
leaps,  or  fmall  corrufcations  on  the  outfide,  which  permit  the  eledric  fluid  to  fpread  gradu- 
ally over  its  inflde  furface,  and  prevent  the  undulations  from  being  fo  ftrong  as  to  caufe  a 
difcharge. 

After  this  explanation  of  the  caufe  of  the  flafhes,  or  corufcations,  which  are  feen  upon 
the  uncoated  part  of  a  jar  while  charging,  and  alfo  that  fuch  corufcations  produce  undu- 
lations, which  terminate  in  a  fpontaneous  explofion  ;  it  remains  now  to  explain  how  a  jar 
is  charged  when  the  corufcations  are  prevented  by  breathing  upon  the  uncoated  part. 

When  a  coated  jar  is  breathed  into,  and  then  fubjedled  to  the  procefs  of  chargino-,  the 
ele£lric  fluid  is  forced  into  it,  along  the  wire  in  the  infide  to  the  coating,  where  it  infl:antly  and 
equally  fpreads  itfelf  over  the  whole  coated  part,  and  at  the  fame  time,  though  with  difficulty, 
and  confequently  gradually.  It  fpreads  itfelf  over  the  uncoated  part,  taking  the  condenfed  film 
of  humidity  for  its  conduftor,  as  it  proceeds  from  the  edges  of  the  coating  upwards  towards 
the  month  of  the  jar,  according  to  the  arrangement  of  the  particles  of  moifture,  and  rifes 
Jiigher  or  lower,  depending  entirely  on  their  arrangement,  and  the  force  with  which  it  is  re- 
belled from  the  machine.  If  the  conducing  particles  be  almoft  uniformly  diffufed  over  the 
uncoated  part,  the  v/hole  jar,  in  the  infide,  will  become  charged,  though  the  uncoated  part 
■will  be  charged  in  a  much  kfs  degree  than  the  coated,  on  account  of  the  imperfeftiori 
of  the  conducting  particles  which  has  adhered  to  its  furface ;  no  corufcations  will  be 
perceived,  on  account  of  the  gradual  and  equal  difFufion  of  the  eleftric  fluid  over  its  infide 
furface  :  and  though  the  charging  be  continued,  yet,  if  the  exhaled  conducting  particles  be 
favourably  diffufed,  no  fpontaneous  explofion  will  happen  from  one  coating  to  the  other, 
along  the  uncoated  furface,  but  the  jar  will  either  be  perforated,  or,  if  it  be  of  fuihcient  ftrength 
to  refifl  that  eifeft,  the  eleftric  fluid  will  be  feen  to  run  in  a  ftream  over  the  mouth  of  the 
jar,  as  quickly  as  the  machine  fupplies  it.  Whenever  a  fpontaneous  eledlric  explofion 
happens,  it  muft  be  from  a  body  of  fufficient  bulk  and  conducing  property  to  con- 
tain that  quantity  of  ele£tric  fluid  at  that  point  from  which  it  explodes,  otherwife  no  explo- 
ijon  ever  happens.  But  the  humid  conducing  particles  are  juft  fufhcient  merely  to  admit  the 
cleftric  fluid,  by  the  aftion  of  the  machine,  to  be  fpread  over  the  furface  of  the  glafs,  but  in 
no  part  of  fufficient  denfity,  either  to  receive,  or  contain  an  explofion.  If,  therefore,  a 
fpontaneous  explofion  do  happen,  it  muft  either  proceed  from  the  infide  coating,  or  the  wire 
which  is  connected  with  it  to  the  outfide ;  and,  if  we  examine  the  ftate  of  the  coating,  we 
Ihall  underftand,  that  the  edge  of  the  coating  (from  which  part  only  it  is  ever  poffible  to 
explode),  and  alfo  above  it,  to  a  fhort  diftance  upwards,  is  as  flrongly  charged  as  the  coated 
part ;  and  by  the  aCtion  of  the  machine  it  is  fo  ftrongly  loaded  with  eleCtric  fluid,  that  it  is 
repulfive  in  all  directions,  which  keeps  back,  or  entirely  (tops,  a  fpontaneous  explofion  from 

the 


Charging  of  'Jars. — St/lplate  of  Strontian  In  Gtouce/lerfhire.  53  J 

the  edge  of  the  coating.  With  regard  to  the  wire,  the  only  place  from  which  it  explodes 
fpontaneoufly,  is  that  part  which  is  nearly  of  an  equal  height  with  die  edge  of  the  mouth  of  the 
jar.  The  fluid  is  nearly  as  much  condenfed  on  this  part  as  on  the  other,  fo  that  an  explofion 
from  the  wire  is  hindered  by  the  fame  caufe  as  from  the  coating.  A  jar  under  fuch  cir- 
cumftanccs  cannot,  therefore,  explode  fpontaneoufly ;  but  the  fluid  will  run  over  the  edge  of 
the  jar  as  quickly  as  the  machine  furniihes  it,  when  its  charging  capacity  is  full. 

I  have  ftated,  at  page  530,  that  a  jar  of  the  dimenfions  there  given,  being  clean  and  dry, 
can  only  contain  a  charge  fufllcient  to  fufe  2  inches  of  a  certain  wire,  and  when  breathed 
into,  its  charging  capacity  will  be  fo  much  encreafed,  that  it  will  contain  a  charge  fuflicient 
to  fufe  8  inches  of  the  fame  fort  of  wire ;  and  a  battery  of  i  j  jars,  in  the  firft-mentioned 
ftate,  can  only  fufe  20  inches,  and  in  the  laft-mentioned,  60  inches.  This  increafed  charg- 
ing capacity,  proceeds,  no  doubt,  from  the  particles  of  moifture,  though  not  from  their  afting 
as  a  coating,  as  has  been  fuppofed,  but  by  their  being  brought  into  a  ftate  or  capacity  of  re- 
(ifting  a  fpontaneous  explofion,  fo  that  a  ftronger  charge  is  forced  in  upon  the  coated  part. 
Some  of  the  eleftric  fluid  which  was  forced  upon  the  uncoated  part  to  a  certain  height 
(perhaps  ^  an  inch,  more  or  lefs,  according  to  the  degree  of  dampnefs,  and  the  fituation  of 
the  particles)  may,  indeed,  be  difcharged  along  with  that  from  the  coated  part  j  but  this 
is  of  little  importance,  and  by  no  means  capable  of  producing  that  increafed  eficft,  which, 
as  I  have  fhewn  by  experiment,  would  require  an  addition  of  feven  jars  to  a  battery  of 
fifteen. 


II. 

Dtfcovery  of  Sulphate  of  Strontian^  near  Sodbtiry,  in  Glouceflcrfnre.     By  G.  S.  GiBBZS, 


B.  M.    F.  R.  S. 
To  Mr.  NICHOLSON. 


I 


SIR, 


F  the  following  imperfeft  analyfis  fliould  meet  your  approbation,  I  fhall  feel  myfelf  flat- 
tered by  feeing  it  noticed  in  your  excellent  monthly  publication. 

I  have  the  honour  to  be, 

Sir, 
Bath,  Your  humble  fenant, 

No.  28,  Gay-ftreet.  GEORGE  SMITH  GIBBES. 


A  friend  of  mine,  the  Rev.  Mr.  Richardfon,  fome  little  time  fince,  (hewed  me  a  fpecimcn 
of  a  fubftance  which,  he  fiid,  was  found  in  great  abundance  in  the  neighbourhood  of  Sod- 
tury,  in  Gloucefterfhire,  where  it  was  ufed  for  the  purpofe  of  making  gravel  walks.  The 
ftone  was  compofed  of  a  vaft  number  or  fmall  cryftals,  which  cohered  together  with  but 
little  force.  The  cryftals  were  eafily  reduced  to  powder,  and  were  not  afll'fted  by  any  acid. 
i  expofed  equal  parts  of  thcfe  cryftals  in  the  ftate  of  a  fine  powder  and  charcoal  to  the 

3  Z  2  adioii 


53^  On  the  Comndum  Stone  from  Afia, 

aftion  of  heat,  and  I  found,  on  pouring  the  muriatic  acid  on  the  fubftance,  when  cool,  that 
there  was  a  great  difengagement  of  fulphurated  hydrogenous  gas. 

I  filtered  this  folution  in  muriatic  acid,  and  I  found  the  cryftals  exaflly  fimilar  to  thofe 
which  I  had  often  formed,  by  adding  the  muriatic  acid  to  the  flrontian  eartli,  found  in  Scot- 
land. This  muriate  poflefl'ed  the  property  of  changing  the  flame  of  the  candle  to  a  moft 
beautiful  red  colour.  A  copious  precipitation  was  formed,  when  the  fulphuric  acid  was 
added  to  a  folution  of  this  muriate.  From  thefe  experiments,  and  from  the  external  charac- 
ters of  the  ftone,  I  have  no  hefitation  in  believing,  that  it  is  compofed  of  the  fulphuric  acid 
and  ftrontian  earth. 

P.  S.  Should  you  wifli  to  poflefs  a  fpecimen  of  tliis  fubftance,  on  receiving  a  line  from  you, 
I  will  take  tlie  firft  opportunity  of  fending  one  to  you. 


III. 

On  the  Corundum  Stone,  from  Afia.     By  the  Right  Honottrable  CHARLES  GREFILLEy  F.  R.  S. 

(Continued  from  p.  485,  Vol.  II.) 


M. 


LR.  Tranckell,  who  refides  in  Ceylon,  and  from  whofe  communications  I  derived  lately 
much  information,  had,  about  five  years  ago,  a  fapphire,  the  greater  part  blue,  and  the  re- 
mainder of  a  ruby  colour.  I  faw,  in  Rome  de  L'Ifle's  colledlion,  at  Paris,  a  fmall  gem,  which 
was  yellow,  blue,  and  red,  in  diftinft  fpots,  and  he  called  it  oriental  ruby."  M.  de  la  Metherie,  ta 
avoid  the  confufion  of  the  denomination  oriental  ruby,  with  oftoedral  ruby,  calls  it  a  fapphire : 
with  more  corre£tnefs,  I  think,  the  above-mentionened  gems  fliould  be  clafled  as  argillaceous, 
under  the  denomination  of  corundum.  I  am  not  uninformed,  that  corundum  is  faid  to  be 
found  in  France.  The  Count  de  Bournon  is  convinced,  that  the  fpecimens  mentioned  in 
Crell's  Journal,  as  having  been  found  by  him  in  a  granite  in  the  Forez,  were  corundum.  M. 
Morveau  alfo  fays,  he  found  it  in  Bretagne ;  but  the  Abbe  Hauy,  in  No.  28,  of  the  Journal 
des  Mines,  aflerts,  that  the  corundum,  found  in  France,  is  titanite ;  he  docs  not  fay  whether 
this  obfervation  extends  both  to  the  corundum  of  Bretagne  and  that  of  the  Forez.  In  the 
fame  manner  I  had  obferved  in  the  fpecimens,  which  Mr.  Rafpe  called  jade,  or  a  new  fub- 
ftance from  Tiree,  on  the  weft  coaft  of  Scotland,  a  great  refemblance  to  corundum ;  but,  hav- 
ing then  only  had  a  curfory  view  of  the  fubftance,  I  am  indebted  to  Mr.  Hatchett  for  the 
examination  of  a  fpecimen  of  it,  which  he  had  from  Mr.  Rafpe's  colleftion.  The  Tiree  ftone 
lefembles  cryftallized  corundum  of  the  coaft,  in  texture  and  colour ;  it  is  alfo  as  refraftory, 
when  examined  by  the  blow-pipe,  with  different  fluxes.  Its  fpecific  gravity  is  3,049;  confe- 
quently  nearer  the  fpecific  gravity  of  pure  corundum  than  the  above-mentioned  lump,  2,785, 
and  the  matrix  of  corundum,  2,768.  The  Tiree  ftone  will  fcratch  glafs  readily,  but  not  rock 
eryftal  j  Its  hardnefs,  therefore,  correfponds  with  that  of  the  matrix  of  corundum.  The 
fubftance  of  the  lump,  defcribed  in  page  481,  cuts  glafs  and  rock  eryftal,  and  the  Tiree 
ftone,  readily. 
It  will,  therefore,  be  fufficient  for  me  to  fay,  that  there  is  great  probability  corundum  may 

be 


On  the  Corundum  Stone  from  Afia,  537 

be  found  in  Great  Britain,  and  en  the  Continent  of  Europe,  as  well  as  in  Afia ;  and  the  above 
flight  eflays  may  {how,  that  obfervations  on  corundum,  in  its  different  {lates  of  purity,  may 
lead  to  accurate-diftinftion  between  fubftances  hitherto  imperfeftly  known,  and  will  lead  to 
a  revifion  of  the  filiceous  genus,  whereby  the  argillaceous  gems  may  obtain  its  due  pre-emi- 
nence in  mineralogy.  When  gems,  by  art,  or  by  rolling  in  the  beds  of  rivers,  have  been  de- 
prived of  the  angles  of  their  cryftals,  they  are  unavoidably  fubje£led  to  uncertain  external 
charafters,  which  even  great  praftice  cannot  render  certain  ;  and  hence  the  unwillingnefs 
of  European  Jewellers  to  deal  in  coloured  gems.  I  have  fome  fpecimens  of  a  fapphire-bluc 
ftone,  India  cut,  very  fmall  and  pellucid  •,  they  were  purchafcd  in  India  as  fapphires,  and 
were  fuppofed  to  be  fluor  by  a  lapidary  in  London,  but  are  cyanite.  The  above  could 
fcarcely  have  happened,  if  the  ftones  had  been  of  fufficient  fize  and  value  to  require  much 
examination,  the  weight  and  degree  of  hardnefs  being  exceedingly  deficient.  The  colour» 
therefore,  will  not  be  a  fafe  guide.  The  diamond,  whether  white,  blue,  red,  yellow,  or  green^ 
can  be  diftinguifhed  by  its  cryftal,  or  by  its  fpecific  gravity  and  hardnefs,  or,  when  it  is 
poliflied,  by  its  luftre.  Other  ftones,  which  compofe  the  order  of  gems,  might  equally  depend 
'  on  their  cryftallization,  fpecific  gravity,  polifli,  and  hardnefs,  for  a  diftindl  arrangement. 
The  near  relation  of  argil,  which  Bergman  gave  to  this  order,  is  dally  confirmed ;  and  it 
will  be,  perhaps,  to  Mr.  Klaproth,  more  than  to  any  other  exifting  chemift,  that  we  fliall  owe 
purcorre£l  information  on  the  fubjeft  of  other  gems,  as  we  do  on  the  fubjedl  of  corundum. 

Many  of  the  varieties  of  corundum,  particularly  the  coloured  and  tranfparent  forts,  witia  their 
regular  cryftallizations,  are  yet  dtjtderata.  Many  cryftallized  ftones,  from  defeft  of  colour, 
luftre,  &c.  are  of  little  value  in  the  market,  fuch  as  jargon,  chryfolite,  tourmaline ;  and  an 
infinity  of  unnamed  ftones  of  Ceylon,  Pegu,Siam,  &c.  would  be  valuable  to  the  mineralogift,if 
obtained  adhering  to  their  ftrata,  and  in  cryftals,  when  external  form  is  not  obliterated.  I  have  no 
doubt,  when  it  is  known  how  much  fuch  information  will  tend  to  illuftrate  the  hiftory  of  the 
earth,  and  particularly  that  of  gems  :  the  fpirit  of  enquiry,  fo  laudably  afloat  in  Britifti  India, 
will  be  dire£ted  to  attain  it.  I  have  not  heard  of  any  metallic  veins  being  found  in  corundum, 
unlefs  a  ftone,  which  Alonfo  Barba,  lih.  i,  c.  13,  defcribes,  fliould  give  an  inftance.  •'  The 
chumpi,  fo  called  from  its  grey  colour,  is  a  ftone  of  the  nature  of  emery,  and  contains  iron  ;  it 
is  of  a  dull  luftre,  difficult  to  work,  becaufc  it  refifts  fire  long.  It  is  found  at  Potofi,  at 
Chocaya,  and  other  places,  with  the  minerals,  negrillos,  and  roficleres." 

Having  mentioned  tlie  varieties  of  cryftallized  and  amorphous  corundum,  and  the  mifcella- 
neous  lafts  relative  to  my  colleftion  of  that  fubftance,  from  India  and  China,  it  might  be  fuffi- 
cient to  give  an  icon  of  the  cryftal,  and  clofe  a  paper  already  prolix ;  but  having  with  fatisfaftion 
obferved,  within  the  laft  years,  the  fcience  of  mineralogy  gaining  ground  in  Great  Britain,  from 
the  knowledge  acquired  by  feveral  gentlemen,  who  have  exammed  the  mines,  and  formed  per- 
fonal  acquaintances  with  the  moft  learned  and  experienced  men  on  the  continent,  and  alfo  from 
ingenious  foreigners,  who  have  communicated  their  obfervations  on  Englifti  foffils,  and  con- 
nefted  the  n  with  the  moft  approved  fyftems,  it  may,  perhaps,  be  accepted  as  a  fufficient  apology 
for  what  follows  j  that  I  confider  it  as  a  defideratum  to  Englifh  mineralogifts,  to  be  invited  to  a 
preference  of  permanent  charafters,  which  the  ftudy  of  cryftallization  has  collected,  and  which. 

promife& 


ijS  On  the  Cirunditm  Stone  from  AJta, 

promlfes  ta  be  a  certain  method  of  afccrtaining  the  laws,  by  which  ele£ltvc  attraction  flvrnngcs 
and  combines  molecules  of  matter.  It  is  true,  the  progrefs  of  cryftallography  has  been  ex- 
tremely flow,  and  different  nations  have  contributed  to  its  prefent  improvement.  It  is  rather  re- 
mavkable,  that  theearlicit  treatife  on  metallurgy,  of  authority,  was  publilhed  in  Italy,  by  Va- 
noccius  liiringuccius,  jufl  before  Agricola  publilhcd  his  Treatife,  in  1546,  in  Germany  -,  and 
the  firfl  treatife,  on  the  Stru£lure  of  Cryftals,  I  know,  is  alfo  from  Italy,  by  Nicolas  Steno; 
Prodromt4S  Dijfertatwnis  de  Solido  intra  SoUdtim  nattiralitcr  content 0.  Florientis,  1669,  in  /^ta. 
A  work  of  great  merit.  Louis  Bourguet  of  Neufchatel,  in  his  Lettres  fur  la  Formation  des  S,-/s 
et  des  Cr^aux.  Amfi.  1729,  lima,  connecled,  by  obfervation  and  meafure,  triangular  and 
rhomboidal,  and  cubic,  and  pyramidal  tetraedal  molecules,  for  all  different  fubftances.  His 
contemporary,  Maurice  Antoine  Capeller*,  attempted  to  deduce  a  fyftem  from  geometrical 
principles  ;  and  in  this  ftate  did  Linnxus  find  the  fubjecl,  when  he  attempted  to  reduce  the 
fcience  of  minerals  to  external  charafters,  and  cryftallized  bodies  to  falts. 

None  of  the  obfervations  of  Linnxus  will  prove  ufelefs  to  fcience  ;  but  his  fyftem  alarmed 
the  chemifts  and  mineralogifts,  who  rcjefted  every  other  criterion,  than  internal  charafter 
from  analyfis,  and  the  fyftem  of  Cronftedt  was  preferred  by  general  affent.  By  this  means, 
a  fpirit  of  controverfy  deprived  the  chem.ift  and  lythologift  of  mutual  afliftance  ;  and  the 
general  opinion  was  correft,  on  the  fuppofition,  that  a  mixed  fyftem  of  chemical  and  external 
characters  would  be  irreconcileable  ;  but  it  has  been  admitted,  even  by  thofe  who  moft 
decidedly  oppofed  Linnjeus's  fyftem,  that  the  beft  fyftem  of  mineralogy  fliould  be  founded 
on  external  and  internal  characters  combinedf.  Among  the  few,  who  ventured  to  exprefs 
their  obligations,  at  the  fame  time,  to  Linnxus,  and  to  Cronftedt,  was  Baron  Born,  whofe 
abilities  and  charader,  in  addition  to  his  diftin£tion,  as  one  of  the  counfellors  of  mines  of  his 
Imperial  Majefty,  obtained  his  inrolment  among  the  fellows  of  the  Royal  Society.  He  con- 
nected the  intrinfic  and  extrinfic  characters  of  minerals,  in  tlie  Index  Foflilium,  which  he 
publiftied  in  1772.  In  Sweden,  Bergman's  Treatife  on  the  Forms  of  Cryftals,  publifhed  in 
the  Upfal  Tranfactions,  in  1 773,  was  a  more  authoritative  recommendation  to  the  invcftigation 
of  the  principles  of  cryftallization  ;  and  it  can  be  of  little  importance  for  me  to  add,  that 
lince  I  have  polTeffed  the  collection  of  Baron  Born,  in  1773,  I  have  had  every  confirmation 
of  the  fame  opinion.  The  progrefs  of  chemiftry,  and  of  cryftallography,  applied  to  minera- 
logy, has  rendered  the  examination  of  ftrata,  and  of  mines,  a  fource  of  amufement  as  well  as 
jnftruCtion ;  and  the  arrangement  of  interefting  facts,  in  the  chemiftry  and  mechanifm 
of  nature,  fuits  my  occafional  refearches  in  geology,  which,  from  variety  of  avocations  and 
circumftances,  have  been  very  much  interrupted.  My  acknowledgment  of  obligation  to  the 
learnedj  who  have  made  this  progrefs  in  fcience,  is  the  beft  recommendation  I  can  give  to 
others  to  examine  their  works.  Thofe  whofe  talents  and'  time  are  devoted  to  the  inveltlgation 
of  every  mineral  fubltance  can  have  no  refpite  to  their  labour  5  minerals,  in  every  ftate  of  their 

*  Prodomus  CryflaUographice,  &c.  and  Littcras  ad  Schcuzerum,  de  Cryftallorum  Gcnerationt.  Aft.  Nat. 
Cur.  vol.  14.     Append,  p.  9. 

f  Nullum  itaque  eft  dubium,  quin  hnjufmodi  metb.odus  mixta,  quss  notis  chsrafterifticls  tarn  extrlnfi-cis 
r^uam  intrinfccis  fimu!  combinatis,  eft  fupeiftrufta,  proximc  ad  naturalem  accedcns,  maximam  indicans  fym- 
mctriaw,  relicjues  fit  pneferenda  methodis,  J,  G.  VVailcrius,  de  Syftemate  Mincralogico  rite  condcndo.  §.  102. 

formation, 


On  the  Corundum  Stom  from  Afia.  -  539 

formation,  perfecllon,  and  decompofition,  as  they  occur  in  mines,  muft  have  their  qualities  im- 
mediately afccrtained,  and  be  referved  for  profit,  or  thrown  away  on  the  heap.  The  pra£tical 
miner  could  not,  without  external  characters,  make  any  progrefs.  The  valuable  minerals  arc 
foon  pointed  out  by  afiiiy,  and  their  appearance  numbered.  The  accuracy  of  feleftion  depended, 
in  all  periods,  much  on  tlie  experience  of  the  miners.  It  remained  for  Mr.  Werner  to  give 
tlic  utmoft  degree  of  accuracy  which  irregular  external  characters  can  acquire,  by  fixing 
appropriate  terms  to  all  the  characters  which  occur,  and  which  the  fenfes  can  difcrimi- 
natc.  In  1774,  he  opened  his  fyftem  of  external  charafters  of  minerals;  and  the  per- 
fection he  has  fince  given  to  it,  has  rendered  it  very  general.  The  Lefkean  colleiEtion, 
arranged  after  Mr.  Werner's  metliod,  has  procured  in  Mr.  Kirwan  a  powerful  fupport 
to  the  introduction  of  that  fyltem  in  this  country ;  and  we  Iiave  already  fome  other 
valuable  publications,  to  recommend  and  introduce  other  favourite  fyftems  of  the  conti- 
nent. It  is,  tlierefore,  at  this  time,  the  Englifli  mineralogiit  Ihculd  be  invited  to  examine, 
if  not  to  prefer,  permanent  chara£ters,  fo  far  as  the  progrefs  of  cryftallography  has  col- 
lected them,  or  at  leaft  to  give  them  a  diftinguiilied  rank  among  external  characters  of 
bodies. 

If  prejudice  too  long  has  retarded  the  union  of  intrinfic  and  extrinfic  chara£ters,  it  has 
alfo  occafioned  a  fchifm  among  the  advocates  of  cryftallography. 

Rome  de  L'Ifle,  in  thejear  1772,  publilhed  the  firft  edition  of  his  Eflay  on  Cryftallogra- 
phy, wlilch  he  ftates  to  be  a  fupplement  to  Linnaeus ;  and,  by  the  affiftance  of  a  very  few 
friends,  he  was  enabled  to  increafe  the  number  of  cryftals  in  a  degree  to  affume  the  appear- 
ance of  a  fyftem.  He  told  me  that  the  accuracy  of  his  meafurement  of  angles  of  minute 
cryftals  was  the  acquireaient  of  great  practice ;  but  that  the  Count  De  Bournon,  after  a 
fhort  practice,  attained  equal  corretStnefs,  and  afforded  him  affiftance,  which  he  acknowledges, 
in  his  fecond  edition,  to  have  received,  particularly  by  the  difcovery  of  cryftals  in  Dauphinc, 
Auvergne,  Franche-Comte,  &c. 

The  Abbe  Hauy,  an  accurate  and  patient  obferver,  and  a  good  mathematician,  confidered 
cryftallography  as  founded  on  certain  laws,  reducible  to  demon'ftration  by  calculation.  In 
the  beginning,  the  differences  of  Bourguet  and  Capeller  were  not  more  pointed  than  thofe  of 
"Rome  de  L'Ifle,  and  the  Abbe  Hauy ;  but  the  progrefs  of  obfervation  and  calculation  having 
demonftrated  their  mutual  utility,  the  obferver  and  meafurer  of  cryftals  will  now  reft  fatisfied 
only  when  calculation  confirms  adual  meafurement.  To  the  Abbe  Hauy  is  alfo  due  a  late 
fcheme  to  fimplify  calculation,  by  expreffing,  according  to  algebraical  formulae,  the  different 
laws  which  determine  the  modification  of  cryftals.  So  far  as  they  are  the  refult  of  calcula- 
tion and  meafurement,  we  may  admit  the  laws  of  calculation ;  for  whenever  the  fuperpofition, 
or  fubtradtion,  of  fimple  or  compound  molecules,  on  a  nucleus,  Ihall,  by  calculation,  give  a  fc- 
ries  of  planes  and  angles,  which  correfponds  exadtly  to  the  angles  and  planes  meafured  on 
natural  cryftals,  it  will  amount  to  no  more  nor  lefs  than  a  demonflration  of  the  rule  or  ar- 
rangement of  ele£tive  attraction  by  figures. 

Thefe  laws  may  be  reduced  to  fimple  practice ;  for  inftance,  the  Abbe  Hauy,  by  meafuring 
the  rhombic  plane  of  corundum,  found  its  two  diagonals  to  be  as  »wo  to  three :  which  gives 

to 


54®  C«  the  Corundum  Stone  from  Afta. 

to  its  acute  angle  8i°  47'  10",  and  to  its  obtufe  angle  98°  12'  50"-,  the  fame  as  martial  vi- 
triol*. The  forms  of  fragments  in,  corundum  are  all  acute  rhomboids.  The  cofme  of  the 
little  angle  in  corundum  is  one-feventh  of  the  radius ;  but  in  calcareous  fpar,  the  cofme  is 
one-fifth  of  the  radius ;  in  fchorl  two-fifths  of  the  radius  •,  in  the  garnet,  one-third ;  and  in  rock- 
cryftals,  one-feventeenth.  Thus  the  application  of  general  laws,  to  afcertain  conftant  cha- 
racter, after  they  fhall  have  been  fully  verified,  may  be  very  fimple  and  general.  It  will  not 
require  perfeft  cryftals;  for  when  cryftals  feparate  into  laminae,  which  fubdivide  into  frag- 
ments, and  fliew  the  form  or  arrangement  of  their  molecules,  it  is  eafy,  from  fuch  frag- 
ments, to  conneft  them  with  their  primitive  cryftal,  and,  confequently,  with  their  clafs.  It 
will  be  a  great  ftep,  to  obtain  one  regular  and  permanent  external  charafter. — Attention  to 
other  charafters  will  be  neceffary,  to  afcertain  the  nature  of  the  fubftance ;  and  other  ex- 
ternal charafters,  fuch  as  irregular  frafture,  colour,  &c.  muft  be  reforted  to,  when  no  per- 
manent characters  exift  j  but  from  their  nature  they  are  fallible,  and,  in  fa£t,  are  feldom 
conclufive. 

The  progrefs  of  cryftallography  appearing,  to  me,  of  -confequence  to  the  progrefs  of  mi- 
neralogy, induced  me  to  defire  the  Count  de  Bournon,  above  mentioned,  one  of  the  honour- 
able vlftims  to  his  allegiance  to  his  king,  to  defcribe  fuch  cryftals,  in  my  coUeftion,  as  Ihewed 
the  different  known  modifications  of  corundum ;  which  will  develope  the  theory  of  cryftal- 
lization,  fo  far  as  is  confiftent  with  the  avowed  obje£t  of  this  paper.  The  fubje£t,  I  believe, 
has  not  hitherto  been  fubmitted  to  the  confideration  of  this  fociety.  The  tranflation  of  the 
Count  de  Bournon's  defcription  has  been  carefully  made,  to  preferve  its  clearnefs  ;  and,  I  hope, 
it  will  be  favourably  received  by  the  Society,  and  make  fome  amends  for  my  tedious  intro- 
duftion.  After  it,  I  have  added  a  table,  connecting  in  one  view  the  fpecific  gravities  of  co- 
lundum,  &c.  herein  mentioned,  with  thofe  given  by  other  authors. 

\An  Analytical  Defcription  of  the  Cr^aUitie  Fonns  of  Corundum,  from  the  EaJl~IndieSy  and  from 

China.     By  the  Count  D£  BouRNON, 

"THE  raoft  ufual  form  of  corundum  is  a  regular  hixsedral  prifm  (Plate  XXIV.  Fig.  i.) ;  in 
general,  the  furface  of  the  cryftal  is  rough,  with  little  luftre,  owing  to  unfavourable  circum- 
ftances,  under  which  It  is  cryftallized. 

The  cryftals  of  corundum,  hitherto  found,  were  not  formed  in  cavaties,  where  each  cryft  J 
being  infulated,  its  furface  could  preferve  that  fmoothnefs,  and  natural  brilliancy,  which  are 
common  to  all  fubftances  that  freely  aflume  a  cryftalline  form.  Like  the  cryftals  of  feldfpar 
which  -we  meet  with  in  the  porphyroid  granites,  the  corundum  cryftals  have  been  enveloped, 
at  the  time  of  their  cryftallization,  by  the  fubftance  of  the  rock,  which  was  forming  at  the 
fame  time  with  themfclves,  in  an  imperfeft  and  confufed  cryftalline  mafs ;  and  the  corundum 
cryftal,  before  it  had  acquired  its  perfeCt  folidity,  neceffarily  received  on  its  furface  the  im- 

*  This  refolt  is  extrafted  from  the  Journal  de  Phy fique ;  but  it  appears,  from  the  Journai  des  Mines,  Na  28, 

«hat  the  Abbe  Hauy  has  fmce  reftified  t^is  mcafurc,  and  giv<n  Sfl"  »6'  for  the  acute  angle,  and  930  34'  for 

the  obtufe  angle. — G.  _    . 

preuion 


I  On  the  ey^aUine  Forms  of  Corundum,  |4t 

jteflion  of  the  difierent  particles  of  the  rock  which  enveloped  them  :  this  naturally  render* 
the  furface  rough  and  dull.  Cryftals  of  feld-fpar,  formed  in  the  granitic  porphyroid  rocks, 
exhibit  the  fame  kind  of  appearance,  from  the  fame  caufe. 

The  corundum  cryftals  are,  in  general,  opaque,  or  at  leaft  they  have  only  an  imperfe£l 
tranfparency  at  the  edges;  when  broken  into  thin  fragments,  the  pieces  are  femi-tranf- 
parent ;  when  held  between  the  eye  and  the  light,  and  examined  with  a  powerful  lens,  it  will 
be  perceived  that  their  interior  texture  is  rendered  dull,  by  an  infinite  number  of  fmall  flaw%r 
"Crofling  each  other,  much  refembling  the  medullary  part  of  wood,  when  it  is  viewed  in  the 
fame  manner.  The  degree  of  tranfparency  of  the  fmall  interftices,  which  are  between  thefe 
flaws,  is  further  evidence  that  this  texture  of  fmall  flaws  occafions  opacity,  which  augments 
in  proportion  to  the  thicknefs  of  the  fragments. 

This  kind  of  internal  ftrufture  has  alfo  a  very  ftrong  analogy  with  that  of  feld-fpar  in 
granite  and  porphyry.  The  endeavour  to  fplit  thefe  cryftals  in  a  direction,  either  perpen- 
dicular, or  parallel  to  their  axes,  meets  with  a  very  confiderable  refiftance:  they  may,  in- 
deed, be  broken  in  thefe  diretlions ;  but  the  rugged  and  irregular  furface  of  the  broken  parts* 
clearly  proves  that  the  dire£tion  in  which  the  cryftalline  laminae  have  been  depofited  one  upon 
another  has  not  been  followed. 

The  regular  hexaedral  prifm  of  thefe  cryftals  cannot  therefore  be  confidered  as  the  form 
of  the  nucleus  of  the  cryftal ;  and,  confequently,  is  not  the  primitive  form  of  the  cryftals  of 
this  fubftance. 

If,  in  order  to  difcover  the  direftion  of  the  cryftalline  laminae,  a  variety  of  cryftals  be 
examined,  fome  will  hardly  fail  to  be  met  with,  which,  on  their  folid  angles,,  formed  by 
the  junction  of  the  fides  of  the  prifm,  with  the  planes  of  the  extremities,  prefent  fmall 
ifofceles  triangles.  Thefe  are  fometimes  greater,  and  fometimes  fmaller,  and  form  folid 
angles,  of  1 22°  34',  with  the  extreme  planes  of  the  cryftal.  They  are,  in  fome  inftances, 
real  faces  of  the  cryftal,  but  moft  frequently  they  evidently  are  the  efFeil  of  fome  violence 
on  that  part.  The  fmoothnefs  and  brilliancy  of  thefe  fmall  faces,  in  the  latter  cafe,  fhew 
that  a  piece  has  been  detached  in  the  natural  direction  of  cryftalline  laminae.  It  is,  indeed, 
much  lefs  difHcult  to  feparate  a  portion  of  the  cryftal  at  thofc  angles,  than  at  any  other 
part }  and  in  following  the  natural  direftion  of  the  faces,  with  a  little  patience  and  dexterity, 
all  the  cryftalline  laminse  may  be  detached,  and  progrefhvely  increafe  the  fize  of  the 
triangular  face. 

This  operation,  however,  cannot  be  done  jndifcrimlnately  on  all  the  folid  angles  of 
the  cryftals,  but  only  on  the  alternate  ones  at  the  fame  extremity,  and  in  a  contrary  direc- 
tion to  each  other.  As  to  the  other  angles,  they  may  be  broken,  but  it  is  impoffible  to  de- 
tach them.  When,  inftead  of  the  folid  angles  of  an  hexaedral  prifm,  fmall  triangular  planes 
are  met  with  (which  frequently  happens,  whether  caufed  by  violence  or  otherwife),  they 
are  always  placed  in  the  direction  above  mentioned.  If  by  following  this  indication  of  na- 
ture, we  continue  to  detach  the  cryftalline  laminie,  we  fhall  at  laft  caufe  the  form  of  the 
hexaedral  prifm  to  difappear  totally,  and  in  place  of  it,  a  rhomboidal  parallelopiped  will  be 
obtained  (fig.  2.),  of  which  the  plane  angles  at  the  rhombs  will  be  86°  and  94°;  the  folid 
Vol.  II. — March  i  799.  4  A  angles 


543  On  the  cr\j]iaU'ine  Forms  of  Corundum. 

angles  at  the  fummit  *  will  meafure  84°  31' ;  and  that  taken  at  the  reunion  of  thebafis  will 
be  95°  29'. 

"We  can  fplit  this  parallelopiped  only  in  a  direftion  parallel  to  its  faces ;  it  will  ftill  con- 
fequendy  preferve  the  fame  form,  which  is  that  of  the  nucleus  of  this  fubftance,  and  its 
primitive  form.  It  is,  therefore,  hy  a  modification  of  the  rhomboidal  parallelopiped 
(fig.  2.)  that  nature  has  formed  the  regular  hexaedral  prifm  (fig.  i.)  which  this  fubftance 
prefents. 

For  if  we  conceive  that  in  any  period  whatever  of  the  increafe  of  the  rhomboidal 
parallelopiped,  a  feries  of  laminae,  or  cryftalline  plates,  has  been  depofited  on  all  the  fides  of 
the  parallelopiped  ;  and  that  thefe  laminse  have  all  undergone  a  progreffive  decreafe  of  one 
row  of  cryftalline  molecules,  at  the  acute  angle  which  tends  to  form  the  fummit ;  and  alfo 
along  the  fides  of  the  oppofite  acute  angle  (fig.  3.  and  4.);  there  will  neceflarily  refult  from 
the  continuation  of  this  fuperpofition,  to  a  certain  period,  an  hexaedral  prifm,  terminated 
by  two  tricdral  pyramids,  placed  in  a  contrary  direftion  ;  and  thgir  planeS)^  or  faces,  which 
form  a  folid  angle,  of  147°  26',  with  the  fides  of  the  prifm,  will  be  either  pentagonal 
(fig.  3.)  or  triangular  (fig.  4.).  They  will  alfo  have,  in  place  of  a  fummit^  an  equilateral 
triangular  plane,  fometimes  greater  and  fometimes  fmaller. 

If  the  fuperpofition  continues,  the  equilateral  triangular  plane,  on  the^mmlt,  will  be- 
come nonagonal,  and  there  will  remain  no  other  traces  of  the  primitive  planes  of  the 
rhomboidal  parallelopiped  than  fmall  ifofceles  triangular  planes  (fig.  5.) :  if  the  fuperpofitioa 
ftill  continues,  until  the  laft  cryftalline  lamina  is  reduced  to  a  fingle  molecule,  or  point, 
no  appearance  of  the  rhomboidal  parallelopiped  will  then  remain ;  and  the  cryftal  refulting 
from  this  operation  of  nature  will  be  a  regular  hexaedral  prifm  (fig.  i .). 

In  the  fame  manner,  viz.  by  a  decreafe  on  the  lower  edges  of  the  laminje,  the  primitive 
rhomboidal  parallelopiped  of  calcareous  fpar  pafles  to  a  regular  hexaedral  prifm  of  that  fub- 
ftance, though  more  frequently  it  does  fo  by  a  decreafe  on  the  lower  angles  of  the  laminae. 
When  the  lamina;  of  the  corundum  cryftal  have,  during  their  fuperpofition  on  the  planes 
of  the  primitive  rhomboidal  parallelopiped,  experienced  a  progreflive  decreafe  at  one  of  their 
acute  angles,  and  along  the  fides  of  the  other,  at  the  fame  time,  and  in  the  fame  proportion, 
it  is  eafy  to  conceive  that  the  height  of  the  hexaedral  prifm  muft  be  the  fame  as  that  of  the 
rhomboidal  parallelopiped,  upon  which  it  has  been  formed.  The  height  B  C  (fig.  i.) 
muft  therefore  bear  the  fame  proportion  to  the  line  A  B,  drawn  through  the  middle  of 
the  two  oppofite  fides  of  the  planes,  on  the  extremities,  as  the  whole  height  E  F  of  the 
rhomboidal  parallelopiped  (fig.  2.)  bears  to  tlie  fmall  diagonal  G  H,  from  one  of  the  rhombs, 
that  is,  nearly  as  6, 45  :  5. 

But  although  this  exaft  proportion  appears  in  a  very  great  number  of  corundum  cryf- 
t^ls,  yet  we  meet  with  fome,  whofe  lengths  are  more  or  lefs  confiderable  \  and  this  is  owing 

•  For  greater  dearnefs,  this  rhomboidal  parallelepiped  may  be  confidcred  as  being  formed  bythejunflion 
•f  two  triedral  pyramids,  bafe  to  bafe  ;  and  the  two  folid  angles  (each  of  which  is  formed  by  the  re- 
union of  three  of  the  acute  angles  on  the  pl.ncs  of  the  rhomb)  will  then  be  confidercd  as  the  fiitnmitsof  tbefe 
fyraisidi. 

to 


On  the  cryJIaUine  Forms  of  CovunduDi.  c^j 

to  different  clrcumftances,  which  have  exifted  at  the  time  of  their  cryilallization.  \fe  may 
conceive,  for  inftance,  that  if  before  the  progreflive  decreafe  of  the  cryltalline  laminae^ 
in  the  manner  above  mentioned,  the  increafe  of  the  rhomboidal  parallelopiped  had  taken 
place,  by  a  fuperpofition  of  laminx,  in  which  the  rovi's  of  cryflalline  molecules  experienced 
a  progreflive  decreafe  along  the  edges  of  the  acute  angle  of  the  bafe  only  (fig.  6.),  and  that 
(the  fides  of  the  prifm  having  already  acquired  a  certain  length)  the  fucceeding  cryltalline 
laminse  had  experienced  a  decreafe  at  the  acute  angle  of  the  fummit,  the  fame  regular 
hexaedral  prifm  would  have  refulted  from  this  procefs ;  but  the  proportion  between  the 
height,  and  the  line  drawn  from  two  of  the  oppofite  fides  of  the  planes,  on  the  extremities, 
would  have  been  much  greater  than  that  of  6,45 :  5,  and  confequently  this  prifm  would 
have  been  longer  than  that  of  the  rhomboidal  parallelopiped,  which  ferved  as  its  nucleus. 
On  the  other,  hand,  if  the  increafe  of  the  rhomboidal  parallelopiped  had  taken  place,  by  a 
fuperpofition  of  cryflalline  laminse,  decreafing  at  the  acute  angle  of  the  fummit,  and  fomc 
time  after  decreafing  alfo  along  the  fides  of  the  acute  angle  of  the  bafe  (fig.  7.),  the  regular 
hexaedral  prifm  refulting  from  this  procefs,  would  have  been  (horter,  in  proportion  to  the 
duration  of  the  mode  of  decreafe  in  the  cryflalline  laminse,  which  were  firfl:  depofited.  There 
are  fome  of  the  hexaedral  prifms,  in  corundum'cryftals,  which  are  fo  Ihort,  that  they  appear 
no  more  than  fegments.  Calcareous  fpar  ofiers  the  fame  phenomenon  ;  as  do  likewife  all 
the  fubftances  in  which  the  hexsedral  prifin  has  any  analogy  of  formation,  with  that  which  we 
have  here  defcribed. 

It  happens  frequently,  when  the  fuperpofition  of  the  cryftalUne  laminae  does  not  go  oti 
equally  on  all  the  faces  of  the  rhomboidal  parallelopiped,  that  one  or  two  only  of  the  folid 
angles  of  the  hexxdral  prifm,  taken  alternately,  ftill  fhew,  by  fmall  ifofceles  triangular 
planes>  fome  remains  of  the  faces  of  the  parallelopiped,  while  the  others  do  not  fhew  any 
at  all. 

Mr.  Greville,  in  his  colle£lion  of  this  fubftance,  has  a  cryftal  of  corundum,  upon  one 
-fide  of  which  only  two  of  the  planes  of  the  rhomb  have  experienced  an  equal  and  perfe£l 
fuperpofition,  while  there  has  been  but  a  very  fmall  number  of  cryflalline  laminje  depofited  on 
die  third  plane.  Confequently  this  cryftal  prefents  a  regular  hexaedral  prifm,  one  of  whofe 
folid  angles  is  fo  much  truncated,  that  the  half  of  the  plane  of  the  end  of  the  hexaedral 
prifms  difappears  (fig-  8.);  and  this  cut,  or  feflion,  forms  an  angle  of  122°  34'  with  the 
plane  on  the  extremity. 

It  is  unneceflary  to  obfcrve,  that  the  regularity  of  the  hexaedral  prifm  depends  on  that  of 
the  rhomboidal  parallelopiped,  on  which  it  is  formed. 

When,  by  detaching  the  laminse  from  the  alternate  folid  angles  of  the  regular  hexaedral 
prifm,  the  planes  refulting  from  this  operation  begin  to  run  into  one  another  -,  and  the  cryftal 
begins  to  afTume  the  form  of  the  rhomboidal  parallelopiped,  to  which  it  owes  its  origin ;  we 
frequently  fee  the  furface  of  thefe  new  planes  divided  into  an  immenfe  number  of  fmall 
rhombs,  formed  thereon  by  the  interfe£tion  of  lines,  that  are  parallel  to  the  fides,  which  be- 
long to  the  rhomboidal  form  of  the  new  faces  (fig.  9.). 

Thefe  lines  are  owing  to  the  extremities  of  the  laminse,  which  have  been  depofited  on  the 
•"ferior  faces,  correfponding  with  thofe  on  which  we  obferve  them ;  and  they  ferve  to  cor- 

4  A  2  ,     roborate 


544  On  the  Dlff'erettee  tfBffeli  in  Over/hoi  and  Breajl  Wheels. 

roborate  ftUl  further,  the  demonftration  we  have  given  of  the  formation  of  the  regular  hexae?* 
dral  prifm  in  this  fubftance. 

(To  be  concluded  in  our  next.) 


IV. 

On  Water-iuheets. 
To  Mr.  NICHOLSON. 


SIR, 


OUR  attention  to  the  Inquiries  fent  laft  month,  Induces  me  to  tranfmit  the  annexed 
japer  for  your  conCderation. 

Your  opinion  that  a  float-board-wheel  is  preferable  to  a  bucket,  agrees  with  that  of  an  ex« 
perienced  mill-wright. 

I  hope,  through  the  medium  of  your  valuable  Journal,  the  fubjedl  will  receive  further  dlf-< 
cuflion ;  as  the  ground  on  which  the  preference  is  given  is  not  obvious. 

It  will,  no  doubt,  be  agreeable  to  you  to  learn,  that  the  fphere  of  your  Journal's  ufeful  com* 
munication  is  extended  to  the  northern  verge  of  Ireland ;  and  that,  amidft  the  tumult  of  po* 
litical  ftrife,  the  arts  of  peace,  and  the  interefts  of  fcience,  are  not  yet  forgotten. 

I  am,  your  obliged  reader, 
Fthfuary  l-j^Z,  DeKRIENSI*. 


On  Water-wheels. 


THE  effe£l  of  water-wheels,  arlfing  from  the  gravitating  power  of  the  water ;  to  retain 
die  water,  feems  the  point  neceflary  to  be  attended  to,  in  the  conftru£lion  of  the  wheel. 

The  form  of  the  bucket-wheel  feems  bed  adapted  to  this  end ;  yet  in  ftreams,  where  the 
fall  is  not  confiderable,  a  preference  is  given  to  float-board-wheels. 

Why  is  this  preference  given  to  float-board-wheels  ?  Suppofe  a  ftream  which  has  a  fall  of 
£x  feet,  and  a  fupply  which  renders  it  equal  to  the  power  of  fix  horfes: 

Allow  this  power  to  be  adequate  to  raife  a  given  weight,  one  foot  high,  thirty  times  in  a 
minute. 

It  is  convenient  to  have  a  water-wheel  of  ten  feet  diameter.  A  bucket-wheel  is  made  of  a 
width  adequate  to  the  fupply  of  water.  Will  this  wheel  be  lefs  competent  to  the  work  than 
a  large  float-board-wheel  ?  If  fo,  to  what  is  the  lofs  of  power  in  the  fmall,  or  the  gain  of  power 
in  the  large,  wheel  owing  ? 


WITHOUT  entering  minutely  at  prefent  into  the  fubjeft  here  ofl^ered  for  confideration, 
which  I  leave  to  my  other  correfpondents,  I  fliall  only  remark,  that  the  preference  feems  to 
have  been  given  to  the  clofe  breaft-wheel,  for  ftreams  afibrding  confiderable  quantities  of 

water 


On  the  Difference  ofEffeB  in  Overjhot  and  Breaft  Wfieels.  545 

water  with  a  low  fall,  for  the  following  reafons :  i .  The  load  upon  the  bucket-wheel  pro- 
duces more  friflrion,  on  the  extremities  of  the  axis,  than  is  produced  in  the  bread- 
wheel  by  the  water,  during  its  paffage  down  the  channel.  That  this  reafoning  is  good, 
may  be  {hewn  by  a  very  familiar  experiment.  Let  any  wheel  be  made  to  reft  on  its 
pivots,  and  then  turned  round ;  it  will  gradually  lofe  its  velocity,  by  the  friftlon,  to  a 
certain  point,  when  it  will  ftop  all  at  once.  The  fuddennefs  of  this  ftop  will  indicate 
the  magnitude  of  the  friftion.  If  this  be  fmall,  the  velocity  will  much  more  gradually 
decay  thart  in  the  contrary  cafe.  On  the  other  hand,  to  (hew  the  friftion  at  the  fur- 
face  of  a  fluid,  let  a  bowl  be  filled  with  water,  and  the  fluid  be  ftirred,  fo  as  to  give 
it  an  horizontal  motion ;  it  will  be  found,  that  this  large  and  heavy  mafs,  bearing  on 
a  furface  fo  very  much  exceeding  that  of  the  pivots  of  the  wheel,  will  turn  round  for 
a  confiderable  time,  and  lofe  its  motion  by  very  imperceptible  gradations :  whence  it  will 
follow,  that  the  fri£lion  is  much  lefs.  2.  In  the  ufual  conftru£lion  of  overfhot-wheels, 
part  of  the  fall  is  loft,  in  delivering  the  water,  at  a  certain  diftance  below  the  vertex, 
and  part  of  its  a£Hon  is  loft,  by  its  running  out  of  the  buckets,  before  it  has  arrived  at 
the  loweft  point  of  the  revolution.  3.  It  is  a  general  notion,  that  large  wheels  go 
fteadier,  from  their  operating  in  the  manner  of  a  fly,  by  means  of  their  inertia;  and 
wheels  have  been  a£tually  conftrufted  of  iron,  with  a  view  to  this  efi'eft.  The  breaft- 
wheel  is  always  larger  than  the  overftiot-wheel,  under  like  circumftances ;  and  it  may 
be  conftrufted,  under  certain  limitations,  of  as  large  a  fize  as  the  engineer  may  think 
fit.  4.  It  is  true,  that  a  breaft-wheel,  of  any  fize,  might  be  converted  into  a  bucket- 
wheel,  and  carry  down  the  water  in  its  buckets,  inftead  of  its  being  fuffered  to  Aide 
down  the  ufual  channel.  But,  when  we  imagine  this  converfion  to  take  place,  we  fee; 
at  once,  that  the  aftion  would  be  lefs  fteady,  from  the  fucceflive  filling  of  the  bucket*, 
and  that  the  lower  portion  of  the  loaded  periphery  would  difcharge  fome  of  its 
contents  much  earlier  than  the  point  at  which  the  breaft -water  ftream  would  have  ccafed 
to  a£i:. 

The  numerical  computation  of  the  difference  of  effeft  between  one  wheel  and  the 
oAer,  according  to  the  dimenfions  given  in  the  prefent  communication,  may  be  made 
from  the  data  at  page  466  of  our  prefent  volume.  It  is  there  deduced,  that  one 
horfe  will  raife  two  hogftieads  and  a  ha'lf  ef  water,  ^*n  feet  high,  in  a  minute  5  and  this 
effe£t,  from  the  note  at  page  465,  would  require  the  fall  of  twice  that  quantity  of  water, 
as  a  power  to  overcome  friftion,  and  produce  velocity  of  working.  The  ftream  men- 
tioned by  my  correfpondent  muft,  therefore,  afford  415  cubic  feet  of  water  per  minute, 
with  a  fall  of  6  feet,  if  it  be  equal  in  power  to  fix  horfes. 

If  certain  dimenfions  be  affumed  for  the  buckets  of  the  overfliot-wheel,  and  an 
ordinary  breaft-wheel  be  compared  with  it,  the  quantity  and  fall  of  the  wsterj  ufelefsly 
expended  on  the  former,  will  Ihew  the  diilerence  of  effe^.  •? 

W.N. 


On 


54^  Account  of  the  Duration  of  Wood  •woriitig  agahijl  Iran^ 

V. 

On  the  Glajs  Trundles  of  Gtizett  RenAUT ;    and  the  Duration  of  the  Teeth  of  Jlliil-work. 

By  C.  B. 


I 


To  Mr.  NICHOLSON. 
SIR, 


OBSERVE  in  your  Journal  for  January  laft,  an  account  of  Citizen  Molard's  having  fubfti- 
tuted  glafs  in  the  place  of  iron  for  the  trundles  of  lantern  pinions,  which  he  ftates  to  be  much 
preferable  to  the  latter ;  as  he  fays,  caft-iron  wears  out  the  wooden  teeth  they  a£t  againft  in 
about  four  months ;  whereas,  the  glafs,  in  the  experiment  he  made,  wore  tlie  wooden 
teeth  about  one-twelfth  of  an  inch  only  in  eighteen  months. 

The  ufe  of  glafs,  in  the  trundles  of  lantern  pinions,  is  liable  to  many  objeftions ; 
experience,  however,  may  point  out  methods  of  obviating  many  of  thefe  :  but  I  think 
it  right  to  mention,  that  Citizen  Molard  is  extremely  wrong,  when  he  fays,  caft-iron 
wears  out  the  wooden  teeth  in  four  months ;  if  it  does  fo  in  France,  it  is  otherwife  ia 
this  country:  I  have  had  a  mill  of  my  own  at  work  for  thefe  four  years,  in  which 
wooden  teeth  aft  againft  iron,  and  I  have  never  been  obliged  to  get  fo  much  as  a 
new  tooth.  Some  months  fince  I  favr  a  fteam  engine,  at  Meff.  Fifli  and  Yates',  in 
St.  John-ftreet,  which  turns  machinery  for  his  grinding  of  fnufF  and  cutting  tobacco. 
This  machine  was  ereded  by  Mr.  Rennie,  engineer  of  this  city,  in  the  year  1786, 
4nd  has  been  conftantly  at  work  for  about  fifteen  hours  per  day  ever  fmce;  yet  the 
wooden  teeth,  in  the  firft  motion,  which  a£t  on  caft-iron,  had  not  worn  above  one-fixth  of 
an  inch;  and  the  iron  teeth  did  not  feem  to  be  worn  y,  part  of  an  inch:  and  from 
every  appearance,  they  will  work  without  repair  for  ten  or  twelve  years  to  come ;  as 
the  workmen  told  me,  that  they  had  not,  apparently,  worn  any  thing  for  thefe  fix  years 
paft.  They  appeared  to  be  very  well  executed;  but  not  better  than  Mr.  Rennie  ge- 
nerally does  fuch  work. 

By  publifhing  the  above,  you  may,  perhaps,  prevent  an  ill-founded  prejudice  from 
being  taken  againft  the  ufe  of  caft-iron,  in  mill-work;  which,  from  experience,  I  can 
fay,  is  the  beft  material  I  have  known  to  be  ufed. 

I  am,  Sir, 

Your  moft  humble  fen-ant, 
Fd).  4th,  1799.  C.  B. 


I  have  vifited  the  manufaflory  of  Meff.  Fi(h  and  Yates',  and  find  that  the  ftatement 
given  above  is  perfeftly  correal.  It  may  be  prefumed,  that  the  iron  trundles,  men- 
tuned  by  Citizen  Renaut,  at  page  522,  were  either  ill  finiflied,  or  rough  from  the  forge; 
and,  at  all  events,  it  appears,  that  they   ought  not  to  afford  ground  for  any  prejudice. 

againft  good  work  in  the  ufual  materials. 

W.N. 
nO 


Accmmt  of  Dr.  Parr's  Theory  of  Light  and  Heat, 

VI. 

On  Dr.  Pan's  Theory  of  Light  and  Heat.     By  a  CorreJ^ondent. 

To  Mr.  NICHOLSON. 


Ac 


SIR, 


XCIDENT  prevented  my  feeing,  for  fome  time,  your  Journal,  publiflied  in  December 
laft;  and  I  now  take  the  liberty  of  making  a  few  obfervations  on  fome  remarks  of  your  corref- 
pondent,  refpe£ting  Dr.  Parr's  theory  of  light  and  heat*.  He  obferves,  "  with  refpeft  to  Dr. 
Parr's  theory,  that  light  and  fire  repel  each  other,  when  difengaged  from  matter,  it  appears 
to  me  too  fanciful  to  be  folid,  and  too  inconfiftent  to  be  fupported,"  &c. — I  do  not  quote  the 
whole  paffage,  becaufe  I  mean  not  to  commence  a  controverfy  upon  tlie  fubje£l:,  as  from  the 
obfervation  juft  tranfcribed,  as  well  as  from  what  follows,  it  is  evident  that  your  correfpondent 
has  feen  only  the  quotation  in  Dr.  Pearfon's  paper ;  and  as  the  eflay  was  publiflied  before 
the  appearance  of  your  Journal,  I  requeft  only  room  for  a  Ihort  analyfis  of  the  theory,  that 
it  may  not  be,  as  I  fufpedt  it  has  been  in  the  paflage  before  me,  mifunderftood.  I  {hall  take 
up  a  little  fpace  only  in  your  valuable  publication,  but  you  will  allow  me  to  add,  that  M. 
Gadolin  has  fince  publifhed  an  opinion  not  very  different ;  and  that,  when  Count  Rumford 
fpeaks  of  changes  effefted,  not  "  by  any  chemical  combination  of  the  matter  of  light  with 
fuch  bodies  (as  are  expofed  to  it),  but  merely  by  the  heat  which  is  generated  or  excited  by  the- 
light  which  is  abforbed  by  them"  he  in  reality  ufes  the  fame  language. 

Dr.  Parr  does  not  merely  affert  an  opinion,  but  fupports  his  hypothefis  by  mjmerous  and 
well-connedted  fafts.  Light  he  confiders,  with  the  chemical  philofopher  of  the  prefent  day, 
as  a  fubftance  capable  of  combining  with  the  various  bodies  it  meets,  producing  by  that 
means  many  chemical  changes.  Among  thefe,  he  traces  with  peculiar  care  its  influence 
upon  vegetation ;  and  from  the  decompofition  of  water,  afforded  in  the  leaves  of  vegetables, 
feemingly  by  its  power,  he  explains  the  great  variety  of  gafes  expired  by  plants  in  different 
fituations. 

As  light  thus  feparates  oxygen,  and  as  the  latter  probably  contains  heat  in  a  lefs  com- 
pounded ftate  than  any  other  fubftance,  he  fteps  over  the  next  difficulty,  and  fuppofes  that 
it  feparates  heat.  This  is  the  only  ftep  unfupported  by  immediate  fa£l:s ;  but  if  affumed  for 
a  moment  as  an  hypothefis,  the  concurrence  of  numerous  other  fa£ts  will  raife  it  to  a  higher 
rank.  By  what  means  light  and  heat  are  brought  together  in  union,  when  they  are  ingre- 
dients in  inflammable  bodies,  he  pretends  not  to  explain ;  but  if  they  are  really  different  ele- 
ments, as  is  now  generally  believed,  our  not  knowing  the  bond  of  union,  is  no  proof  againft 
its  exiftence.  In  the  examination  of  the  various  explofive  fubftances.  Dr.  Parr  traces  iix 
each  the  fource  of  its  light  and  heat,  and  (hows  by  what  means  the  balance  fubfifting  be- 
tween thefe  aftive  ingredients  is  deftroyed,  fometimes  by  the  addition  of  the  one,  fometimes 
by  that  of  the  other  principle.    There  are  various  explofive  fubftances  which  will  not  ex- 

*  ECTay  upon  Light,  in  a  mifctllaneous  volume,  publilhcd  by  »  fccicty  at  Exeter. 

plodk 


548  Scientific  News — Sitittigs  of  the  Infiitute  at  Cairo. 

plode  without  light,  however  intenfe  the  heat,  and  vice  verfd. — ^This  part  of  the  eflay, 
where  he  examines  the  fource  of  light  in  the  compofition  of  the  body,  and  explains  the 
different  modes  by  which  the  violent  feparation  is  efFeded,  as  well  as  the  confequences  of 
the  explofion,  appears  highly  ingenious. 

Such,  Sir,  is  the  outline  of  the  paper  which  I  think  is  mifunderftood  and  mifreprefented 
by  your  correfpondent.  The  different  parts  can  be  only  fairly  appreciated  by  an  examina- 
tion of  the  fafts.  This  is  a  bufmefs  to  which  I  cannot  now  attend,  and  which  is  not  fuited 
to  your  Journal.    Your  giving  me  a  little  room  for  this  analylls  will  oblige,  Sir, 

Yours, 

A  Constant  Read&r. 


SCIENTIFIC  NEWS  AND  ACCOUNTS  OF  BOOKS. 

Infiitute  of  Cair$. 

(Continued  from  page  5*3,  vol.  II-) 


H  E  fecond  fitting  was  held  on  the  nth  Fruftidor,  at  feven  in  the  morning,  at  which 
Citizen  Andreofly  made  a  report  on  the  fifth  queftion  propofed  by  Buonaparte.  He  ob- 
ferved,  in  the  firft  place,  that  Egypt  poflelfes  no  fulphur,  but  formerly  imported  it  from  Ve- 
nice. The  charcoal  is  obtained  by  burning  the  lupine  in  a  trench,  and  afterwards  fifting  it. 
The  faltpetre  is  native,  and  is  even  faid  to  be  found  in  veins  (par  veines)  round  Cairo.  It 
is  refined  in  the  fame  manner  as  (commonly)  in  Europe.  It  is  a  true  nitrate  of  potafli,  and 
not  of  lime,  as  in  France.  The  boiling  is  made  with  the  ftalks  of  Turkey-wheat,  and  it  )• 
purified  with  whites  of  eggs.  The  gunpowder  is  made  by  hand,  and  the  workmen  arc 
naked.  Each  mortar  contains  fifteen  pounds,  and  the  procefs  lafts  feven  hours.  The 
peftles  weigh  from  nineteen  to  twenty-five  paros.  A  fmall  quantity  of  water  is  added,  and 
the  granulation  is  performed  by  a  fieve.  The  reporter  affirms  that  this  powder  is  very  good\ 
but  that  to  render  it  ftill  better  it  is  neceflary  that  the  proportions  of  France  fliould  be  fol- 
lowed. Two  thoufand  cantars  (were)  formerly  made  at  Cairo,  of  which  much  was  fent  to 
Leghorn.  The  beys  had  very  little  powder.  Murat  Bey  had  no  more  than  1,500  cantars. 
It  would  be  eafy,  fays  the  reporter,  to  augment  this  fabrication,  and  even  to  export  large 
quantities  to  Europe- 

At  the  fame  fitting,  the  citizen  Monge  read  a  memoir  on  the  phenomenon,  called  le  mirage 
by  French  feamen,  and  by  ours  looming.  This  effe<Sl  of  refraftion  was  remarkably  feen  by  the 
French,  in  the  courfe  of  their  march  through  the  defert.  Villages  feen  at  a  diftance  ap- 
peared elevated,  and  as  if  built  on  an  ifland  in  the  middle  of  a  lake.  The  furface  of  this 
apparent  water  became  narrower  as  they  approached,  until  at  length,  when  they  were  only 
at  a  fmall  diftance,  it  difappeared  i  but  the  fame  illufion  prefented  itfelf,  with  regard  to  the 

next 


Scientific  News.— -Accounts  of  Boohs,  i'49 

next  remote  village.  The  author  afcribes  this  phenomenon  to  a  diminution  of  the  denfity 
of  the  lower  ftratum  of  the  atmofphere,  occafioned  by  evaporation  of  water  from  the  fands. 
It  is  impoflible  to  deduce  the  particulars  of  his  theory  from  tlie  mere  report ;  but  it  feems  to 
be  nearly  the  fame  as  that  of  Mr.  Huddart*. 

The  third  fitting  was  held  on  the  \6th  FrttElidor.  Berthollet  read  a  memoir  on  the  forma- 
tion of  ammoniac.  Citizen  Sulkowlky  read  a  defcription  of  the  route  from  Cairo  to  Salehia. 
Egypt  has  hitherto  been  known  only  on  the  banks  of  the  Nile.  The  road  followed  by  the 
French  army  in  purfuit  of  Ibrahim  Bey  was  entirely  unknown.  On  going  out  of  Cairo  by  the 
gate  of  Nafr,  you  enter  the  defcrt,  where  fevera!  forfaken  houfes  were  obferved.  The  village 
of  Elmaria,  on  this  road,  is  the  ancient  Heliopolis.  In  another  village,  called  Elmaria,  there 
were  thoufands  of  palm-trees.  On  the  right  of  this  road,  there  are  nothing  but  deferts  of 
fand ;  but,  on  the  left,  are  many  cultivated  lands.  The  places  which  the  army  pafled  are 
Lacoubey,  Elhanea,  Elmenia,  Belbeys,  Souva,  Coraim>,  Salehia,  and  many  others,  which  it 
merely  pafled  through  in  hade. 

Citizen  Say  fpoke  of  the  methods  of  obtaining  better  means  of  grinding,  and  fhewed  that 
water-mills  ought  to  be  conftrufted. 

C.  Balholet  (q.  Berthollet  ?)  read  a  memoir,  in  which  he  examines  die  gun-powder  of  Cairc 
It  contains  only  five  parts  out  of  thirty-two  of  falt-petre ;  the  reft  is  fulphur,.  charcoal,  earthy 
matter,  and  muriate  of  foda :  fo  that  the  only  means  of  rendering  it  ufefuly  is  to  wifh  out  the  fait ^ 
and  inamfaBure  it  a  fecond  titnt. 

Citizen  Monge  read  a  memoir  on  the  antient  monuments  of  Cairo.  The  fafar,  in  the  ftrect 
which  leads  from  the  Inftitute  to  the  caftle,  prefents  a  vafe  of  granite  with  hieroglyphics 
within  and  without.  It  was  a  tomb,  and  refembles  that  of  the  mofque  of  Alexandria. 
Citizen  Monge  propofes  that  it  be  removed  by  the  Inftitute,  in  order  to  coavey  it  to  the 
Inufeum  of  France.  Near  the  caftle,  after  having  palled  the  palace  of  Jofeph,  there  is  the 
cell  of  a  gate  with  hieroglyphics  well  preferved. 

The  fourth  ftttingf  t\fl  FruElidor.  Citizen  Sulkowlky  read  a  memoir  on  a  buft  of  Ifis.  Say!» 
another  on  the  materials  for  fuel  in  Egypt.  The  commiflion  for  grinding,  annouixced  their 
intention  of  etefting  a  wind-mill.    Citizen  Geoffroy  read  a  memoir  on  the  oftrich. 

The  fifth  fitting,  26th  FruBidor.  The  commiflion  for  fuel,  reported  that  the  ftems  of  car- 
thamus,  reeds,  and  ftraw,  may  be  ufed  for  heating  ovens,  at  lefe  charge  than  in  France. — 
Buonaparte  prefented  the  Connoijfatwe  des  Temps  for  the  year  VII,  and  invited  the  Inflitute  to. 
eompofe  an  almanack.  A  commiflion  was  appointed  for  this  obje£t,  confifting  of  Monge- 
Beauchamp,  Nouette,  and  Raphael.  It  was  at  the  iame  time  decreed,  that  the  three  following 
almanacks  (hould  be  [united,  namely,  that  of  the  Copts,  the  Mufliilmen,  and  die  French. 
Citizen  Fourier  read  a  memoir  on  tlie  folution,  of  algebraic  equations.  Citizen  Parceval,  a 
tranflation  of  a  fragnient  of  Taflb.  Citizen  Defgenettes  read  a  diflertation  on  the  diarrhoea,, 
the  dyfentery,  and  the  endemic  opthalmia,  which  are  more  peculiarly  the  diforders  of  Egypt. 

*  Philofophical  Journal,  I.  145— This  curious  fubjedt,  which  does  not  yet  feem  to  be  adequately  ex- 
plained in  all  its  particulars,  has  employed  the  meditations  of  various  obfervers  j  for  fgme  of  which,  the  rea- 
der may  refer  to  the  authors  quoted  at  page  418  of  our  prefeflt  Tolume:— N, 

Vol.  H.—March  1799.  4  a  The-. 


•.jjC  Scientific  Ni'ws.-—Accautits  of  Booh, 

The  Jtxthfittwg,  on  thefirfl  complementary  d/iy.  Citizen  Beauchamp  prefented  an  annuary, 
ready  for  immediate  printing,  and  alfo  feveral  aftrononiical  obfervatious.  Citizen  Berthollct 
read  a  letter  from  Citizen  Laplace,  announcing  a  correftion  in  the  metre.  He  alfo  gave  an 
account  of  the  manufa6lure  of  indigo,  and  pointed  out  confiderable  improvements.  Citizen 
Fourier  communicated  a  projeft  of  a  wind-mill,  to  water  lands. 

Sixth  fitting,  on  the  6th  Vendemaire,  year  VII.  Citizen  Pouflielque  prefented  a  (ketch  of  a 
new  method  of  analytically  demonftrating  geometrical  theorems,  by  Corancez  the  younger. 
Citizen  Norry  read  a  memoir  on  Pompey's  pillar.  Savigny  defcribed  a  new  fpecies  of 
nymphxa.  A  commiffion  was  charged  with  the  eftablilhment  of  a  fchool  of  defign,  among 
whom  were  Redoute  and  Norry.  Citizen  Coftaz  read  a  memoir  on  the  colours  of  the  fea, 
and  Citizen  Parceval  another  tranflatlon  from  Taflb. 

Eighth  fitting,  Vendemaire,  year  VII.  Fifty  mummies  of  birds,  fent  to  the  Inftitute,  were 
<ielivered  for  examination  to  a  commifRon,  compofed  of  Buonaparte,  GeofFroy,  Dolomieu, 
and  fome  others.  Porte,  a  native  of  France,  and  inhabitant  of  Cairo,  who  is  employed  on 
Indigo,  prefented  famples  to  the  Inftitute.  Citizen  Larrey  read  a  memoir  on  the  opthalmia. 
Citizen  Beauchamp  read  another  on  his  voyage  to  Trebifond.  He  indicates  the  longitude  of 
Ifpahan,  and  obferves,  that  the  longitude  of  Trebifond  is  37°  18'  5"  from  Paris,  and  not  43°, 
«s  Bonne  affirms ;  which  dedufts  more  than  eighty  leagues  from  the  Black  Sea.  Citizen 
Delifle  read  a  memoir  on  the  palm-tree,  which  bears  the  fruit  called  <lomm.  It  is  the  caffio- 
phora  of  Theophraftus.  Citizen  Dolomieu  read  a  memoir  on  the  ftudy  of  ancient  and  mo- 
<lern  geography.  He  fixes  the  pofition  of  the  ancient  Alexandria  between  two  hills  of  cal- 
careous fand-ftone,  and  explained  the  fubfequent  changes.  He  thinks  the  fea  muft  have  rifen  a 
foot  fmce  the  time  of  the  Ptolemies.  Citizen  Norry  made  a  report  concerning  the  fchool  of 
defign ;  and  Citizen  Parceval  read  a  tranflation  from  Taflb. 

Since  the  commencement  of  the  Vllth  year,  a  literary  journal  has  appeared,  under  the 
title  of  Decade  Egyptienne,  fournal  litteraire  et  d'Ecenomie  politique.  The  profpedtus  was 
figned  Tallien,  and  is  compofed  of  thirty-eight  pages.  The  Journal  is  to  appear  every  de- 
cade, each  number  containing  two  and  a  half  or  three  flieets,  in  oftavo.  The  price  per  num- 
ber is  to  be  I  franc  French  money,  or  i  o  francs  per  1 2  numbers.  Subfcriptions  are  taken 
by  Citizen  Marc-Aurell,  printer  to  the  army,  quartier  des  Fran5ois,  at  Cairo.  The  firft 
number  appeared  the  10  Vendermaire,. year  VII.  v 


An  Accotmt  of  the  Operations  canied  on  for  accomplifhing  a  Trigonometrical  Survey  of 
England  and  Wales,  from  the  Commencement  in  1784,  to  the  End  of  the  Year  1796.  Be- 
gun under  the  Dire£lion  of  the  Royal  Society,  and  continued  by  Order  of  the  Honour- 
able Board  of  Ordnance.  Firft  publiftied  in,  and  now  received  from,  the  Philofophical 
Tranfaftions.  By  Captain  William  Mudge,  F.R.S.  and  Mr.  Ifaac  Dalby,  Vol.  I.  Illuf- 
trated  with  22  Copper-plates.  London,  printed  by  Bulmer,  and  Co.  for  Faden,  Cha- 
ring-Crofs,  1799  ;  437  pages.  Price  il.  8s.  boards. 
ALL  Europe  is  acquainted  with  more  or  lefs  of  the  particulars  of  this  furvey,  which  is  a 

work  of  the  utmoft  utility,  and  an  honour  to  our  government,  and  the  parties  to  whom  the 

execution 


Scientific  News. — Accounts  of  Books.  55 1 

execution  has  been  intruded.  The  accounts  having  hitherto  been  publifhed  only  in  the 
Philofophical  Tranfa£l:ions,muftneceflarilyliave  been  of  confined  circulation,  while  the  number 
and  expcnce  of  the  engravings  have  prevented  any  fatisfa£lory  detail  from  appearing  in  ^jther 
publications.  The  geographer  and  man  of  fclence  will,  confequently,  learn  with  greit  plea- 
fure,  that  the  account  of  the  operations,  as  far  as  they  have  yet  been  carried,  together  with 
the  plates  of  inftruments,  furveys,  and  other  refults,  are  to  be  had,  in  a  beautifully  printed 
quarto  volume,  at  a  very  eafy  price. 

The  original  defign  had,  for  its  immediate  obje£l:,  the  afcertaining  of  data,  by  which  the 
difference  in  longitude,  between  the  obfervations  of  Greenwich  and  Paris,  might  be  deter- 
mined. Soon  after  the  death  of  General  Roy,  the  general  furvey  of  th«  kingdom  wjp  com- 
menced, of  which  accounts  were  publifhed,  in  the  Tranfaftions  for  1 796.  And  in  1 798,  Mr. 
Faden  having  determined  on  republifliing  all  the  papers  relative  to  this  objeft,  the  prefident 
and  council  of  the  Royal  Society  rendered  him  the  very  efTential  fervice  of  furnifhing  him 
with  the  original  copper-plates,  and  the  mafler-general  of  the  ordnance  granted  him  permif- 
fion  to  reprint  the  accounts  of  the  fubfequent  trigonometrical  furvey.  This  is  now  done 
under  the  fuperintendencc  of  the  able  men  whofe  names  appear  in  tlie  title  page,  who 
have  omitted  no  care  to  render  this  colleftion  of  equal  value  with  the  originals,  and  in  fome 
few  refpefts  more  fo.  An  account  of  the  changes,  which  the  editors  have  made  in  the  original 
papers,  is  given  in  the  preface ;  where  we  alfo  obferve,  that  Mr.  Faden,  with  the  permifTion 
of  the  Board  of  Ordnance,  intends  to  publifh  a  very  fuperior  map  of  Kent,  in  the  courfe  of 
the  prefent  year,  from  documents  fupplied  by  the  labours  of  the  gentlemen  employed  on 
the  general  furvey  by  government. 


A  public  inftitution  for  difFufIng  the  knowledge  and  facilitating  the  general  introduftion 
of  ufeful  mechanical  improvements,  and  for  teaching  by  courfes  of  ledlures  and  experi- 
ments the  application  of  fcience  to  the  common  purpofes  of  life,  has  been  propofed  to  be 
eflablifhed,  by  fubfcription,  in  London,  by  fome  gentlemen  of  the  firft  refpeftability.  I  have 
feen  a  printed  paper,  containing  the  outlines  of  a  plan,  and  a  lift  of  gentlemen,  who  have 
fubfcribed  fifty  guineas  each,  for  this  purpofe.  As  the  plan  itfelf  is  ftill  under  deliberation, 
with  regard  to  various  efTential  particulars,  and  the  prefent  lift  of  fubfcribers  does  not 
contain  the  whole  of  the  names,  on  account  of  the  rapidity  with  which  that  lift  increafes, 
I  (hall  enter  into  no  further'detail  at  prefent,  than  fimply  to  obferve,  that  the  plan  appears 
to  have  already  met  with  a  degree  of  fupport,  which  is  no  lefs  honourable  to  the  public 
fpirit  of  the  fubfcribers,  than  diftinftive  of  its  own  value  and  importance. 


lb 


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I      N      D      E      X 


TO     THE 


FIRST    AND    SECOND    VOLUMES. 


A, 


A. 


.BERCROMBY,  Lord,  ii.  igr 

Abernethy,  Mr.  John,  F.R.S.  on  the  Fo- 
ramina Thebefii  of  the  Heart,  ii.  142 

AbeiTations,  optical,  explained,  i.  g,  12 

Accum,  Frederick,  on  Light  emitted  by  Bo- 
rax, ii.  28.  On  Argill  and  Magnefia,  ii. 
83.    On  the  Purity  of  Drugs,  ii.  118 

Acer  Saccharinutn,  ii.  304 

Acetous  Acid,  Examination  of  the  Purity  of, 
ii.  no 

and  acetic  Acids,  Chaptal  on  their 

Difference,  ii.  518 

Achmet,  i.   138 

Achromatic  Lens,  partly  formed  of  Fluids, 
i.  4.  Whether  improved  by  cementing 
them  together,  ii.  233 

Telefcope,  i.  i 

Acid,  Sulphureous,  i.  143.  Properties,  Ha- 
bitudes, and  Combinations  of,  i.  313.  Com- 
binations of,  i.  364 

■  Sulphuric,  Effefk  of  on  vegetable  Mat- 

ter, i.  385.  Explanation  of  its  Effcfts  on 
vegetable  Matter,  i.  388.  Examination 
of  the  Purity  of,  ii.  120 

-  Gallic,  i.  274.  ii.  338.  OfTin.Obfcrv- 
ationson,  by  Guyton,  i.  543.  Of  Lemons, 
Preparation  of,  ii.  43.  Camphoric,  ii. 
97.  Nitrous,  Examination  of  the  Purity 
of,  ii.  119.  Acetous,  Examination  of  the 
Purityof,  ii.  120.  Muriatic, Examination 
of  the  Purity  of,  ii.  120.  Boracic,  Examin- 
ation of  the  Purity  of,  ii.  121.  Tartare- 
ous,  Method  of  dctefling  the  Adulteration 
of,  ii.  121.  Of  Amber,  Method  of  deteft- 
ing  the  Adulteration  of,  ii.  122.  Of  Ben- 
zoin, Purity  of  the,  ii.  122.  New  Metal- 
lic, in  Siberian  Red  Lead,  ii.  145.  Pro- 
cefs  for  preparing  the  Camphoric,  ii.  157. 
Oxygenated  Muriatic,  ufed  in  Bleaching, 
ii.  168.  Of  Galls,  Prouft  on  the,  ii.  338. 
Zoonic,  difcovered  by  Berthollet,  ii.  367. 
Nitric,  Produftion  of,  ii.  413 
Acids  for  Bleaching,  i.  89 
Acouftic  Inftruments,  Experiments  and  Ob- 

fervations  on,  i.  417 
Adamantine  Spar,  or  Corundum  Stone,   ii. 

477>  53* 
Adams  on  Mathematical  Inftruments,  i.  192 
George,  Inventor  of  the  Spiral  Gun- 

ter's  Rule,  i.  375 
Adct,   i.  46,  486 
Adulteration  of  Drugs,  &c.  Examination  of, 

ii.  118 
JEgireta  Paulus,  i.  138 
^lian,  i.  138 

jEpinus,  Mr.  on  Magnetifm,  ii.  81 
Aeroftation,  ii.  377 
Affinity,  Chemical,  whether  it  be  not  the 

mere  EfFeft  of  Temperature,  ii.  161 
Vol.11. — June  I79.9. 


Africa,  Travels  in,  by  Mr.  Park,  ii.  253,  325 

Africa,  Geography  of  North,  ii.  253 

African  AtTociation,  ii.  379 

Agamemnon,  ii.  319 

Agnenfis  Albertus,  i.  139  . 

Aikin,  ArthXir,  i.  220.     His  Defcription  of 

the  Angltfca  Copper-works,  i.  367 
Air  Balloon,  Experiment  with  the  Parachute 

from,  i.  ;»3 

—  Cold  ilTuing  out  of  the  Earth,  i.  231. 
Theory  of,  i.  233 

—  Pump,  of  Sir  George  S.  Mackenzie's, 
ii.  28.  By  Mr.  Little,  ii.  501.  Sadler's, 
i.  441.  Of  Prince  and  Cuthbertfon,  i. 
119 

Alton,  Mr.  ii.  333 

Albani,  Prince,  ii.  95 

Akhorne,  Stancfty,   ii.  179,  182.     On  the 

Alloy  of  Gold  with  Tin,  ii.  140.  227 
Aldinus,  Joannes,  on  Galvanifm,  i.  335 
Alexander,  ii.  136 
Alkali,  pure  Cauftic,  economical  Procefs  for 

obtainmg,  i.  329 
of  Tartar,  Impropriety  of  the  various 

Denominations  of,  i.  513 
Alkalis,    Procefs  of  Lowitz  for  rendering 

them  very  pure,  i.  164 
Alloy  of  Gold  with  Tin  proved  to  be  very 

noxious,  ii.  140 
Alum,  Obfetvations  on,   i.  318.     Analyfis 

of,  i.  321 
Amand,  St.  his  Silk  Machine  for  Eleftricity, 

ii.  420 
Amber,  Method  of  detefting  the  Adultera- 
tion of  the  Acid  of,  ii.  12 1 
America,  Difcovery  of,  i.  73,  107.      Prize 

Qucftion   on   the   Difcovery   of,   ii.  328. 

Climate  of  near  the  North  Weftern  Lakes 

of,  ii.  315 
American  Philofophical  Society,  i.  13.  ii.  376. 

Black  Birch,  ii.  333.     Sugar  Maple,  ii. 

304 
Amcricanus,  Vefpucius,  i.  73 
Amicus,  i.  472 
Analyfes  of  Pumice,  ii.  2S9 
Analyticus,  i.  92,  187 
Anchor,  Efcapcment,  ii.  54. 
Anderfon,  James,  L.L.D.  F.R.S.  on  an  uni- 

verfal  Charafter,  ii.  189 

Mr.  ii.  197,  477 

Andrada,  D'.  on  Brazilian  Diamonds,  i.  24 
Andrieux,  Cit.  ii.  236 
Anglefey,lfleof,Accountof  the  great  Copper- 
works  in,  i.  367 
Angclucci,  i.  226 

Animal  Strength  computed,  ii.  466 
Annales  de  Chimie,  Authors  of,  i.  46 
Annealing  Gold  with  Tin,  ii,  179 
Anquetil,  i.  46 
Antiraonial  Soap,  i.  549 


Aphrodifsus,  Alexander,  i.  138 

Apparatus  for  producing  coloured  Shadows, 
i.  104.  For  difengaging  Oxygen  Gas,  by 
J.  Sadler,  Efq.  ii.  33-  For  Experiments 
with  the  common  Blow-pipe,  ii.  36.  For 
producing  Water  by  Con.buftion  from 
Hydrogen  Gas,  ii.  235.  For  Bleaching, 
new,  li.  271 

Appreciation  of  Money  at  different  Periods, 

ii-  284  .         c    \. 

Aqua  Fortis,  double.  Examination  ot  tne 
Purity  of,  ii.  119  - 

Marine,  or  Beryl,  Analyfis  of,  byVau- 

quelin,  ii.  358 

Arabic  Gum,  ii.  409 

Arches,  i.  93 

Archimedes  on  the  Lever,  i.  541 

Architefture,  Military,  ii,  89 

New,  Hydraulic,  i.  96 

Ardent  Spirit,  fpecific  Gravity  of,  i.  117 

Argand,  Cit.  ii.  2 10.  His  Claim  to  the  In- 
vention of  an  Air  Pump,  ii.  368 

's  Lamp,  i.  69 

Argillaceous  Earth,  Method  of  Separation  of, 
from  Magnefia,  ii.  83 

Arms,  Fire,  Improvements  in,  i.  517 

Arnault,  H.  ii.  51 

Arnold,  maintaining  Power  of  his  Time- 
piece, ii.  59 

Arrian,  i.  137 

Art  of  printing  Books  find  Piece-goods  by 
Cylinders,  i.  18 

Artern,  Salt-works  of,  ii.  72 

Artificial  Cinnabar,  ii.  i 

Magnets,  Method  of  making,  by 

Coulomb,  ii.  80 

Afli,  Dr.  i.  530 

Afphaltum,  ii.  203 

Afs,  Propagation  of  the  Zebra  with  the,  ii. 
267 

Athenian  Poplar,  ii.  334 

Atmofphere,  its  Elcftricity,  i.  16 

of  the  Planets,  ii.  40 

Atwood,  i.  168.  ii.  56 

Aublet,  ii.  302 

Auftin,  Dr.  ii.  241,247 

Aviccnna,  i.  138 

Azores  Iflands,  Difcovery  of,  i.  74 

Axis  of  Rotation,  ii.  40 

B. 

Babington,  Mr.  ii.  335,  336,  337 

Bacon,  Lord  Chancellor,  i.  3  5  5 

ii.  201.     On  univerfal  Language,  ii. 

344 
Baker,  ii.  131 
Balance  for  Time-pieces,  i.  57.     Expanfion, 

i.  64 
Baldwin,  i.  139 
Balfour,  Sir  William,  i.  377 

4C  Ban, 


554 

Ball,  William,  Efq.  ii.  53; 

Ballosn,  Air,  Experiment  with  a  parachute 

from  an,  i.  513 
Bancroft,  Dr.  ii.  300 
Banks,  Sir  Jofeph,  i.  97,  loi,  188,  190,  215, 

287,  28S,  308,40+. — ii.  47,  60,  72,  73> 

76,  80,  95,  96,  267,  276 
Bannow,  ancient  Corporation  Town  of,  de- 

ftfoyed  by  the  Sands,  ii.  384 
Bar,  compound,  i.  66.      Iron,    Proccfs  for 

making,  ii.  65 
Barbaroffa,  Emperor  Frederick,  i.  139 
Bardfley,  Samuel  Argent,  M.D.  on  Party 

Prejudice,  ii.  188 
Bark,  of  Paraguatan,  for  dyeing,  ii.  93 
Barnard,  Thomas,  Efq.  i.  190 
Barometer,  Lazowfki's,  New,  ii.  n 
Bartolin,  ii.  199 
Barton,  ProfetTor,  ii.  376 
Barytes,  Habitudes  of,  i.  529.    To  obtain 

pure,  i.  53? 
Bafaltes,  ii.  289 

Bats,  fuppofed  fixth  Senfe  of,  i.  474 
Battery,  Eleftrical,  new  Method  of  meafur- 

inf  its  Force,  i.  156 
Baufre,  Sieur,   Inventor  of  the  horizontal 

Efcapement,  ii.  53 
Bauhin,  Cafpar,  i.  138 
Baume's  Method  of  Bleaching  Silk,  i.  32, 

88.     Hydrometer,  i.  37,  192.  ii.  237 
Beafts,  Peculiarities  of  the  Struflure  of  their 

Eyes  i-  477- 
Beaufuy,  Mr.  ii.  25;,  25S 
Beccaria,  i.  357,  396,  578 
Becher,  John  Joachim,  ii.  344.     His  Scheme 

of  univerfal  Writing,  ii.  347 
Becman,  on  univerfal  Language,  ii.  345 
Beguelin,  i.  106 

Behem,  Martin,  the  firft  Difcoverer  of  Ame- 
rica, i.  73,  107 
Behenira,  Martin,  or  Behem,  Chev.  i.  107 
Bellows,  or  blowing  Machines,  ii.  71 
Benjamin,  Purity  of  the  Flowers  of,  n.  122 
Bennet.Rev.  Abraham,  i.  16,  266,  270,  397 

's  Eleftrometer,  ii.  440 

Bentham,  General,  ii.  96 

Benzoin,  Purity  of  the  Acid  of,  ii.  122 

Bergman,  i.  78,  212,  254,  313,  320.  34°- 

'i-  34i  37.  105,  191,  202,  207,  209,  213, 

340 
Bernier,  ii.  86 
Bernouilli,  Daniel,  ii.  176.     On  Gunpowder, 

'•459 

Berihollet,  i.  32,  46,  95,  142,  168.  On  the 
Combinations  of  Oil  with  Earths,  Alkalis, 
and  Metals,  i.  170,  213,  268,  297,  313, 
331.  ii.  37,  54,  I02,  105,  155,  156,  190, 
268,  269.     On  the  Zoonic  Acid,  ii.  367. 

Berry,  Mr.  ii.  477 

Berthoud,  i.  61 

Berthout,  Cit.  Louis,  ii.  237 

Beryl,  Earth  of,  or  Glucine,  ii.  358,  360, 
393 

Befnier,  Father,  on  the  Union  of  Languages, 
ii.  345 

Bewicks,  Mtff.  ii.  63 

Bigueliii,  i.  587 

Birch,  broad-leaved  American  black,  ii.  333 

Mr.  ii.  420 

Birds'  Eyes,  Obfervaticns  on,  i.  474 

Biringuccio,  ii.  89 

Biron,  Cit.  i.  529 


N 


D 


E       X. 


Bitaube,  Cit.  ii.  23S 

Bitumen,   Proportion!  of  Carbon  in,  i.  487. 

Elaftic,  ii.  249 
Bitumens,  ii.  201,  248,  202,  204 
Black,  Dr.  i.  239,  2S9 

Dye,  ii.  338 

Blagdcn,  Dr.  Sir  Charles,  i.  it8,  347,  49S 
Blair,  Dr.  Robert,   his  Method  of  forming 

achromatic  Lenfes  with  Fluids,  i.  i 
Blanchard's  Afcent  by  means  of  a  Balloon, 

ii-  377 

Bleaching  Raw  Silks,  i.  32,  88 

Apparatus  for,  ii.  271.     Art  of, 

by  P.  des  Charmes,  ii.  427.  Of  Prints, 
Method  of,  ii.  165.  Improved  Proccfs  of, 
ii.  268 

Blondelin  I'Hiftoire  Naturclle  dr.  Valmont  de 
Bomare,  i.  95 

Blow  Pipe,  Obl'ervations  and  Experiments  on 
the  common,  ii.  34 

Blowing  Machines,  ii.  71 

Blue,  Prulfian,  Enquiries  concerning  the 
Nature  of,  by  Prouft,  i.  453 

Tournfol,  Procefs  for  making,  ii.  3 1 1 

Blumenbach,  Mr.  i.  256,  519.     ii.  77 

Bodies,  Inftrument  for  meafuring  the  Vo- 
lumes of,  by  H.  Say,  i.  325 

Boelim,  Martyn.     See  Behem 

Boerhave,  i.  363 

Boiard,  i.  201 

Bondt,  i.  44 

Bones  of  living  Animals  augmented  in  Size 
by  the  internal  Ufe  of  Phofphate  of  Lime, 
i.  201.     Foffil,  Cuvier  on,  ii.  220,  512 

Bonhomme  on  the  Cure  of  Ricketis,  i.  174, 
200 

Bonjour,  i.  9;,  142.     On  Nitre,  ii.  23 

Boracic  Acid,  Examination  of  the  Purity  of, 
ii.  121 

Borax,  luminous  Quality  of,  ii.  28 

Borda,  ii.  38 

Borelli,  ii.  128 

Born,  Mr.  ii.  248 

Borlach,  Mr.  ii.  72 

Bofcovich,  i.  555 

BofTut,  ii.  173,  178 

Botham,  Mr.  ii.  309 

Bouchad,  Cit.  ii.  239 

Bougies,  furgical,  to  make,  ii.  413 

Bouguer,  i.  67.  ii.  86 

Boulton  and  Watt's  Steam  Engine,  ii.  229, 
230,231,265 

Bournon,  Count  de,  on  Cryftaline  Forms,  ii. 
540 

Bovey  Coal,  ii.  206 

Boyle,  Robert,  i.  in,  120,  347 

Bradley,  ii.  118 

Brand,  Mr.  ii.  i 

Brafchi,  Prince,  ii.  95 

Brazil,  Difcovery  of,  i.  7  5 

Brazilian  Diamonds,  Hiftory  of,  i.  24 

Bread,  Method  of  making  of,  without  Ycaft, 
i.  267 

Breathing  into  eleftrical  Jars  to  Increafe  their 
Capacity,  ii.  530 

Brce,  J.  ii.  284 

Brick -making,  ii.  498 

Brockbank,  maintaining  Power  of  his  Time- 
piece, ii.  59 

Brodbelt,  Dr.  Francis  Rigby,  i.  264 

Brook,  A.  i.  121.  ii.  217.  On  the  uncoatcd 
Surface  of  electrical  Jars,  ii.  528 


Brook,  Samuel,  ii.  96 

Brougham,  Henry,  jun. 'Efq.  i.  551.  ii.  147, 

«93 
Brown,  Major,  John,  ii.  227 
■  William,  M.D.  on  an  univerfal  writ- 

ten  Charafter,  ii.  190  " 

Dr.i.  336 


Bruce,  Mr.  ii.  254,  256 

Brugnatelli  on  Phofphorus,  i.  444.  On  loud 
Fulminations  with  Phofphorus,  ii.  468 

Bruhl,  Count,  ii.  58 

Brydune,  i.  225 

Buee,  William  Urban,  Efq.  on  the  Cultiva- 
tion of  the  Clove  Tree,  i.  287 

ButFon,  Count  de,  i.  io6,  587.  ii.  16 

Butter,  keeps  better  after  Fufion,  ii.  357 

Byrne,  John,  ii.  224 

C. 

C.ibral,  Albarez,  i.  108 

Cairo,  Inftituteof,  ii.  522,548 

Caldera,  Ri(berto,  i.  25 

Caliinicus,  ii.  90 

Caloric,  Efffft  of  combuftible  Materials, Prize 

Queflinn  to  determine  the,  ii.  328 
Camphor,  its  rapid  Motions  upon  Water,  i. 

205.      Speedy   DilTolution    produced    by 

Effeft  of  Air  and  Water  thereon,  i.  206. 

Dccompofition  of,  ii.  i;8.     Oil  of,  ii,  99 
Camphoric  Acid,  Proccfs  for  preparing,  ii, 

«37 

Camus,  James,  i.  75 

Cit.  ii.  236 

Candles  rhfir  J'.fFcft  explained,  i.  70 

Candle,  Chinefe,  i.  72 

CanncI  Coal,  ii.  204 

Canton,  i.  270 

Caprino,  cold  Caves  of,  i.  231 

CaramueKhis  Appar:it.Philofophique,ii.  346 

Carbon,  Proportions  of  in  Bitumen  and  Mi- 
neral Coal,  by  Kirwan,  i.487.  Develope- 
mcnt  of,  in  vegetable  Matter,  ii.  208 

Carbonate  of  Potafli,  ii.  369 

Carmineti  BalTan',  i.  335 

Carradori,  M.  Joachim,  M.D.  on  natural 
Phofphori,  ii.  132 

Cartwright,  Mr.  his  new  Pifton  for  Pumps, 
&c.  ii.  364,  476 

Carysfort,  Earl  of,  ii.  224 

Calfini,  i.  99 

Count,  ii.  128,  233,  447 

Caft  Iron,  ii.  104 

■ Steel,  Properties  and  Ufes  of,  ii.  103. 

Manufafture  of,  ii.  102 

Cattk,  Prices  of  at  different  Periods,  ii.  284 

Cavallo,  i.  16.  On  the  Ele£lrical  Multiplier, 
i.  394.     Freezing,  i.  504 

Cavcndifh,  H.  i.  143,  140.  3  57,  499 

On  the  MeaCur^s  of  Eleftricity, 

ii.  216.  On  the  mutual  Gravitation  of 
Bodies  and  Denfity  of  the  Earth,  ii.  446. 

Caves  emitting  cold  Winds,  Account  of,  i. 
229 

Cawley,  i.  412.     ii.  228 

Cement  to  clofe  Vcfftls  air-tight,  i.  472 

Cementation  of  Iron,  ii.  68 

Cefi,  sold  Caves  of,  i.  230 

Chalu',  ii.  102 

Champy,  J.  P.  on  Nitre,  ii.  23 

Changes  of  the  Earth,  Priie  Queftion  on  the, 

ii.  238 
Chapman,  William,  M.R.I.A.  li  96 

Chaptal, 


I 


N 


t) 


X. 


Chaptal,  on  the  Soap  of  Wool,  i.  40.  On  tlie 
cold  Caves  of  Roqueforr,  i.  233.  On  Blow- 
ingMachines,  i;26.  OnNitrc,ii.  13.  On 
the  Caule  of  Difference  between  the  Acet- 
ous and  Acetic  Acids,  ii.  518 

Charafler,  Univerfal,  ii.  189.  By  Dr.  An- 
derfon,  ii.  190.     By  Dr.  Brown,  ii  341. 

Charcoal,  reduces  Metals  in  the  humid  Way, 
ii.  404.  Its  imperfeft  conducing  Power, 
as  to  Heat,  is  of  great  Confequence  in 
Cliemiftry,  ii.  499 

Charj^e,  Elcftric,  Method  of  meafuring,  i. 
156 

Charles  Vth,  i.  109 

Charlevoix,  Father,  ii.  304 

Charmes,  Pajot  dcs,  ii.  417 

Charybdis,  Defcription  of,  ii.  12,  17 

Chauifier,  i.   144,  169,  271.    On  Hats,  i. 

399.  5^0 

Chemical  Affinity,  Doubts  as  to  its  Exift- 
ence,  ii.  161 

■Chevalier,  M.  ii.  Igi 

Chiavenna,  Cold  Caves  of,  i.  131 

Chrome,  a  new  Metal,  ii.  145,  387,441 

Chriftie,  Mr.  i.  598 

Chryfolite,  Analyfis  of,  ii,  414 

Chryftals,  Method  of  obtaining  the  pure  fixed 
Alkalis,  i.  164.  Qoartz,  of  Gibraltar,  ii. 
187 

Cigna,  i.  396 

Cinnabar,  Artificial,  new  and  improved  Pro- 
cefs  for  making,  ii.  z 

Civil  Engineers,  Society  of,  ii.  47,  95 

Cleaning  of  Prints,  Method  of,  ii.  265 

Cleghorn,  Dr.  i.  i86 

Cleomedes,  ii.  184 

Climate  of  Ireland,  change  of  in  modern 
Times,  ii.  385,  431 

Clive,  Lord,  ii.  267 

Clocks,  i.  56,  Obfervations  on  the  Efcape- 
ments  of,  i,  429.  Various  Kinds  of  Ef- 
capements,  for  maintaining  Power  of,  ii. 
49. 

Clofure  of  Veffels,  Method  of,  to  render  air- 
tight, i.  260 

Clouds,  Account  of  Changes  of  Colour  and 
Diredion  of,  i.  265 

Clouet,  i.  142.     ii.  237 

Coal,  Mineral,  Proportion  of  Carbon  in,  i. 
487.     Cannel,  ii.  204,     Bovey,  ii.  206 

Cobalt,  i.  540 

Cockfliutt,  James,  ii.  96 

Cogs,  Wheels  without,  i.  329 

CogOiall's  Rule,  i.  450 

Coin,  Table  of  the  new  French,  i.  199 

— —  Whether  its  exchangeable  Value  can  be 
regulated  by  the  State,  ii.  2C1.  Whe- 
ther it  could  all  be  made  of  one  Metal,  ii. 
26  t.  If  two  or  more  Metals  be  ufed, 
whether  the  State  can  fix  the  Ratio  be- 
tween them,  ii.  262.  If  only  one  be  fixed 
and  the  other  left,  whether  the  dearer  or 
cheaper  Metal  ought  to  be  taken,  ii.  262. 
The  beft  Figure  and  Impreffion  of,  ii.  262. 

Cold,  its  EfFeft  on  volatile  Oils,  by  Marguc- 
ron,  i.  182,  227.  Winds  ilTuing  from  the 
Earth,  i.  229,  EfFefts  of  upon  Water,  i. 
568.  Bta  Method  of  producing  Artifi- 
cial, i.  497 

Collier,  Jofeph,  on  Iron  and  Steel,  ii.  190. 
On  the  Fermentation  and  Diftillation  of 
Ardent  Spirit,  ii.  1 90 


Colman,  Mr.  506 

Colour,  remarkable  Change  of  in  a  Negro, 
ii.  191 

s,  of  Light,  i.  551,  586.     Caufe  of, 

i.  595.  From  Specula,  ii.  194.  '  Veget- 
able, new  and  very  permanent,  ii.  1 5  5. 
new  Phenomenon  6f,  in  flat  Plates  of  Glafs, 

ii.  313 

Coloured  Shadows,  i.  loi.    Apparatus  for 

producing  fame,  i.  104 
Colouring,  prinaiple,  Pruflic,  i.  142 
Columbus,  Chriftopher,  i.  73,  107 
Combination  of  Oils  with  Earths  and  other 

Subftances,  i.  170 
Combrune,  M.  ii.  284 
Combuftion,   Obfervations  on,    i.  350.     Of 

Phofphorus  in  Vacuo,  i.  236.    L.  de  Vinci 

on,  ii.  87 
Comet,  its  Tranfit  over  the  Sun,  ii.  357 
Comets,  Eccentricity  of  the  Orbits  of,  ii.  41. 

Improbability  of  the  Earth  being  deftroy- 

ed  by,  ii.  42 
Compafs,  Mariners,  Account  of  the  bed  Me- 

chanifm  for  the  Sufpenfion  of,  i.  4»5 
CompalTes,  Proportional,  ii.  89 
Compofition  for  extinguifliing  Fire,  ii.  279. 

Of  Salts,  on  the  Tables  of,  ii.  340 
Concuffion,  Detonations  produced  by,  i.  168 
Condillac,  Abbe,  ii.  347 
Condorcet,  i.  69,212.     His  Elements  of  Ac- 
counts, ii.  524 
Conduiftors  for  Lightning,  Obfervations  on 

Metallic,  i.  434,  4.39 
Confifcation  and  Sale  of  Works  of  Art  by  the 

French  in  Italy,  ii.  94 
Congelation,  ii.  163.     Of  Mercury,  i.  143, 

497.     Of  Volatile  Oils,  i.  183 
Conftantinus,  i.  138 
Cooper,  Mr.  ii.  269 
Copernicus,  ii.  40,  84. 
Copper,  Procefs  of  working  the  Ore,  Smelt- 
ing, &c.  i.  368.     Money,  ii.  260.     Native, 

large  Mafs  of,  ii.  508.     Plates,  Glafs  pro. 

pofed  as  a  Subftitute  for,  ii.  60.      Plate 

Impreffions,  Method  of  cleaning,  ii.  265 
Coquebert's  Account  of  the  French  Syftem 

of  Meafures,  i.  193.     Cit.  Charles,  ii.  72 
Corn,  damaged  by  improper  Houfing,  ii.  31. 

Method  of   determining  its    Quality   or 

Strength,  ii.  32 
Cornea  of  the  Eye,  Experiments  on,  i.  474, 

Treatment  of  the  Difeafes  of,  i.  550 
Correal,  Francis,  ii.  94 
Corundum  Stone,  Account  of,  by  C.  Gre- 

ville,  Efq.  ii.  477,  536 
Coflel,M.  i.  170 

Cotton  Tree,  Perfian,  on  the,  ii.  457 
Coulomb,  i.  97.     On  Magnets,  ii.  80,446 
Coxe,  i.  153. 
Cramont,  i.  97 

Crawford,  Dr.  i.  289,  518,  529.  ii,  108,  114 
Crell,  ii.  10 
Creroy,  Mr.  ii.  335 
Creufot,   i.  142 
Crome,  Aug.  Fred.  Guil.  on  the  comparative 

Culture  of  Land,  i.  47 
Cromwell,  Oliver,  ii.  346 
Crown  Wheel  Efcapement,  ii.  50 
Cruickfliank,  Mr.  William,  i,  285,  286,  337. 

His  Analyfis  of  Sugar,  W^ucilage,  &c,  ii. 

406 
Cryftal  Iceland,  ii.  193 


in 

Critftalllne  Forms,  ii.  540 

Culture  of  Land,  i.  47 

Cuming,  Alexander,  i.  59.  His  Efcape- 
ment, ii.  58 

Currents,  hot  and  cold  in  the  Sea,  i.  573 

Curvature  of  Bodies  produced  by  chahgi:  of 
Temperature,  i.  6i 

CurveLines,  of  the  Surface  of  Ellipfoid,  i.93 

Cuthbertfon,  Mr.  John,  his  Air  Pump  de- 
fcribed,  i.  121,  130,  241,  441.  Air  Pump, 
ii.  29.  On  the  Meafurc  of  Elcftricity,  ii. 
»  I  5.  Apparatus  for  producing  Wafer  by 
Combuftion,  ii.  135.  On  Elefelica!  Bme- 
ries,  and  his  univerfal  Eleftrometer,ii.  525 

Cuvier,  Cit.  i.  46.  ii.  237.  On  the  foflil 
■Bones  of  extinft  Animals,  ii.  ^ij 

Cuypers,  C.  on  Glafs,  ii.  420 

Cylinder  Printing,  i.  18 

D. 

Dabovillc,  General,  ii.  38 

Dalby,  Mr.  Ifaac,  i.  J50,  198.  ii.  550 

D'Alembert,  ii.  84,  176 

Dalgarme,  George,  on  an  univerfal  Charac- 
ter,  ii.  345,  418 

Dalton,  Mr.  John,  on  the  Vifion  of  Colour** 
ii.  188  ■■; 

Dalzcl,  Andrew,  M.A.  F.R.S.  Edin.  on  M. 
Chevalier's  Tableau  de  la  Plaine  de  Troye, 
ii.  192 

Damafcus  Steel,  Imitation  of,  i.  469.  ii.  10+ 

D'Andrada,  M.  i.  14 

Dangos,  his  Obfervation  of  the  Tranfit  of  a 
Comer,  ii.  357 

D'Anville,  ii,  256 

D'Arcet,  i.  40.  ii.  37. 

Darwin,  Dr.  i.  107,  397.  ii.  368 

Da  Vinci  Leonardo,  ftiort  Sketch  of  his  Life, 
i.  599.  On  the  Crown  Wheel  Efcape- 
ment, ii.  51.    Manufcripts  of,  ii.  84,  90 

Dead-beat  Efcapement,  ii.  52 

DeBorn,  M.  ii.  249 

De  Cambre,  i.  46 

De  Chaulnes,  i.  590 

Decompbfition  of  Soap,  i.  171.  Of  Water 
by  Eleftric  Difcharges,  i.  241 

De  Cufa,  Nicholas,  ii  84 

Defilement,  Fortification,  i.  94 

De  Fondeur,  Jean,  ii.  51 

De  Gama,  Vafco,  i.  108 

De  Genffane,  on  the  Fufion  of  Ores,  &c.  i. 

»39 
Deiman,  i.  44,  241 
DeUval,  Mr.E.  F.R.S.  ii.  319 
De  La  Hire,  i.  593 
De  La  Lande,  i.  135 
De  L'Epee,  Abbe,  Teacher  of  the  Deaf  and 

Dumb,  ii.  347. 
De  Lifle,  Rome,  ii.  199.     Defaltes,  i.  23  J 
De  Luc,  M.  i.  347 
De  Milly,  i.  69. 
De  Morveaux,  i.  192 
Dtnfity  of  the  Earth,  ii.  446 
Depreciation  of  Money  at  different  Periods, 

ii.  284 
Derham,  Dr.  ii.  50,  354 
Defagulitrs  on  the  Perpetual  Motion,  i.  377. 

On  the  Steam  Engine,  i.  420.  ii.  228.   On 

Water  as  a  firft  Mover,  ii.  462 
De  Sauffure,  H.  B.  i.  97,  190,  229,  511 
Defcartes,  i.  305,  588,  593.     On  univerfal 

Language,  ii.  344 

Defcotils, 


ss^ 


N 


E        X. 


Defcotils,  Cituen,  ii.  91,  337 

Def.ription,  Mineralogical,  of  Gibraltar,  ii. 
i8s„  219.  Geographical,  of  North  Ame- 
rica, by  Renne!,  ii.  253.  Of  the  Country 
near  the  North  Weftcrn  Lalics  of  America, 
ii.  3  I  5 

Dsfcroifilles,  ii.  368 

De  Serra,  M.  Correa,  ii.  254 

De  SefTarts,  i.  46.  ii.  237 

Des  Fontaines,  Cit.  ii.  156 

Defmond's  Patent  for  Tanning,  i.  26 

Defportes,  Felix,  i.  5 1 1 

Detached  Efcapements,  i.  54 

Detonations  produced  by  Concuflion  of  the 
Oxymuriate  with  various  Bodies, by  Four- 
croy  and  Vauquelin,  i.  168.  With  Ox- 
ypenated'Muriate  of  Potafli,  ii.  29a,  469 

De  Trebra,  M.  i.  99 

Deyeux,  i.  228 

D'Harleville,  Cit.  Colin,  ii.  239 

D'Herbelot,  ii.  258 

Diabetes  Mellitus,  i.  285.  ii.  427,  $23 

Diamonds  of  Brazil,  Hiftory  of,  i.  24.  Ana- 
lyzed by  Tennant,  i.  177 

Dies  for  making  Screws,  i.  163 

Dietrich,  Cit.  i.  2  10 

Dilatation,  of  Elaftic  Fluids,  i.  143 

Diofcorides,  ii.  136. 

Dip  of  the  Horizon,  Correftion  for,  i.  151 

Difcovery  of  America,  i.  73,  107.  Prize 
QiJeftion  on  the,  ii.  328 

Difpcrfive  Power  of  Fluids,  Meafure  of,  i.  2 

Diftilled  Vinegar,  Method  of  detefting  the 
Adulteration  of,  ii.  120 

T)']i€  on  Acid  of  Lemons,  ii.  43 

Dodd,  R.  on  the  Tunnel  beneath  the  Thames, 
ii.  239,473 

DoUond,  i.  I.  ii.  234 

Dolomku,  i.  98,  359 

Donation,  Prize,  by  Count  by  Rumford,  i. 
t88 

Dondi,  his  ancient  Watch,  ii.  51 

Doubler,  Eleftrical,  Manipulation  of,  i.  397. 
ii.  368 

Drainage  without  Machines,  ii.  491 

Drugs,  Examination  of  the  Purity  of,  ii.  1 18. 

Dryden,  ii.  13 

Drynefs  of  the  Atmofphere,  Precurfor  lef 
Rain,  i.  511 

Du  BuilTon,  ii.  43 

Da  Cangc,  i.  138 

Duhamel,  M.  ii.  105,  190,  307 

Dumcutier,  Cit.  ii.  210 

Dunaghoo,  Mr.  ii.  224 

Duncan,  Dr.  i.  264.  Andrew,  jun.  M.D. 
and  Andrew,  fen.  M.D.  Annals  of  Medi- 
craefi.287.      Andrew,  jun.  M.D.  ii.  265 

Duncombe,  John,  ii.  96 

DundonaU),  Lord,  on  Coal,  i.  48  7.  His  Coal 
Tar,  i.  494 

Dupont  de  Namurs,  i.  47 

Dupratz,  ii.   304 

Durer,  Aibtrt,.  ii.  89 

Dutch  Cbemifts  on  carbonated  Hydrogen,  i. 
44. 

DuTernois,  i.  235 

Duviilard,  i.  46. 

Dyanniere,  i.  49. 

Dyeing,  New  Bark  for,  called  Paraguatan,  ii. 

93 
Dye,  Black,  ii.  339 
Dying,  a£(lfted  by  the  Soap  of  Wool,  i.  43 


Earth,  Sydney,  Doubts  concerning  its  Ex- 
jftence,  i.  404.  Fufibility  of,  i.  142.  Fi- 
gure, Rotation,  and  Projeftion  of,  ii.  39. 
Improbability  of  its  being  deftroyed  by  a 
Comet,  ii.  42.  Sydney,  docs  not  exift,  ii. 
72.  Arj^iilaceous,  Method  of  Separation 
of  from  Magnefia,  ii.  83.  Rotation  of  the, 
proved  by  Experiment,  ii.  84.  Leonard 
de  Vinci's  Theory  of,  ii.  84.  Ancient 
State  of,  ii.  85.  Theory  of,  ii.  86.  Fi- 
gure of,  ii.  184.  Prize  Q^eftion  on  the 
Changes  of,  ii.  238.  New,  or  Glucine, 
ii.  359,  39;.  Its  Denfity  deduced  from 
Experiment,  ii.  446 

Eaftburne,  Henry,  ii.  96 

Eaton,  on  the  Arts  in  Turkey,  ii.  355 

Eau  de  Luce,  i.  80,  166 

Eccho,  remarkable,  lieard  from  an  Air  Bal- 
loon, ii.  377 

economical  Laboratory  of  Guyton,  ii.  210. 

Ecphantus,  ii.  185 

Edgeworth,  Richard  Lovell,  Efq.  F.R  S.  and 
M.R.I.A.  on  the  Telegraph,  ii.  319.  Mr. 
Lovell,  jun.  ii.  314 

Edinburgh,  Tranfaftions  of,  ii.  191 

Edrifi,  ii.  256 

Edwards,  Bryan, Efq.  ii.  280.  Mr.  ii.95.  33* 

Eimbke,  Dr.  ii.  8 

Elaftic  Strings,  i.  328.     Bitumen,  ii.  249 

Eleftric  Charge,  Method  of  meafuring.i.  156. . 
Filh,  Account  of  the  Organs  of,  i.  357. 
Intenfity,  Meafure  of,  i.  87 

Eleflrical  Machines,  i.  83.  Defcription  of  a 
new  Portable,  by  Mr.  Pearfon,  i.  506. 
Doublet,  Manipulation  of,  i.  397.  Inftru- 
ment.  New,  i.  1 7.     Power  of,  meafured,  ii. 

215.  By  Friftion,  of  Silk.  ii.  420 
Eleftricity,  i.  48.     Spining  Condenfer  of,  i. 

i5.  New  Phsenomenon  of  its  Undulation, 
i..  83.  Of  the  Torpedo,  explained,  i.  355. 
Multiplier  of,  Obfervations  on,  i.  394. 
Hiftory  and  Account  of  the  Proccffes  for 
accumulating,  i.  396.  Pofitive  and  Nega- 
tive, i.  433.  Apparatus  for  Experiments 
of,  ii.  435.     Meafure  of  the  Power  of,  ii. 

216.  Obfervations  on,  ii.  396,  420,  438, 

Eleftrometer,  Defcription  of  an  improved,  i. 

270.  ii.  439,441,  515 
Eleftrophore,  Obfervations  on  the  AAion  of, 

'•355 
Elers,  Mr.  ii.  319 
EUicott,  his  Pendulum,  i.  60.     Andrew,  on 

the  Phenomenon  of  Looming,  i.  152 
Emanations  of  Odorant  Bodies,  i.  153,431 
Emery,  ii.  54 

Enclyclopedie  Methodique,  i.  48 
Engine,  Steam,  Hiftorical  Remarks  on  the 

Invention  of,  i.  419.     Comparifon  of,  i. 

422.     Boulton  and  Watt's,  ii.  230.     Mr. 

Sadler's,  ii.  231.      Working  by  a  Pifton, 

Account  of,  ii.  228 
Engineers,  civil,  Origin  of  the  Society  of,  ii. 

47,95 
Engraving  on  Glafs  Plates  for  Printing,  ii. 

60.     On  Wood,  ii.  63 
-^ s,  Method  of  cleaning  of,  ii.  265. 

Machine  for  Ruling  the  Lines  of,  ii.  429 
Eolian  Harp,  Defcription  of,  ii.  12 
Equations,Quadratic;Rule  for  their  Solution, 

«•  »19 


Eratofthenes,  ii.  136,  238 

Efcapement,  Crown  Wheel,  ii.  i;o.  'De- 
fcriptions  of,  various,  ii.  50.  Dead-beat, 
ii.  52.  Horizontal,  ii.  53.  Free  or  de- 
tached, ii.  54.  Common  Anchor,  ii.  54. 
Free,  of  Mudge,  ii.  56.  New,  by  Nichol- 
fon,  ii.  ;9.  New,  for  Watches,  by  Mr.  J, 
Prior,  ii.  363 

Ether,  Vitriolic,  produces  Cold  by  Evapora. 
tion,  i.  50-4 

Eudiometers,  i.  141.  With  the  Sulphatt 
of  Potafli,  by  Guyton,  i.  268 

Euler,  ii.  176 

Euftathius,  ii.  16 

Evaporation,  its  EfFeft  as  to  Refraflion,  i. 
1 46 

Evelyn,  Sir  Geo.  Shuckburgh,  Bart.  F.R.S. 
and  A.S.  his  Table  of  Prices  of  Provifion, 
&c.  ii.  284 

Excife,  afFcfts  Paper-ftaining,  i.  23.  Af- 
fefls  Soap-making,  i.  43 

Excitation  of  Elcftricity,  ii.  438 

Expanfion  Bar,  i.  63.  Balance,  i.  64.  Of 
Metals,  i.  58 

Extinguilhing  Fire,  Compofition  for,  ii.  279 

Extradlion  of  Oil,  ii.  90 

Eye,  Nature  of  the  Procefs  of,  to  produce 
diftinft  Vifion,  1.305,472.  Deprived  of 
tire  Chryftaline  Lens,  i.  311.  Of  Birds, 
Obfervations  on,  i.  472.  Experiments  on 
the  Cornea  of,  i.  .J74.  Obfervations  on 
the  focal  Adjuftment  of,  i.  476.  Of  Qua- 
drupeds and  Birds,  Peculiarities  of  Struil- 
urc  of,  i.  477.  Of  Fiflies,  Peculiarities  of 
the  Strufture  of,  i.  478,  547.  Imperfec- 
tions of  the  Sight  of,  i.  549.  Treatment 
of  the  Difeafes  of,  i.  550 


F. 


Fabbroni,Sig.Gio.  i.  496.  On  the  Bleaching 
of  Engravings,  ii.  265.  On  the  Extinftioi* 
of  Fire,  ii.  279 

Fabriguette,  Michael,  i.  40 

Faden,  William,  ii.  96 

Falcandus,  Hugo,  i.  139. 

Falconet,  ii.  50 

Fata  Morgana,  Account  of,  i.  225,  285.  ii. 
416 

Faujas,  i.  48,  494 

Fajello,  ii.  19 

Feathers,  Cock  and  Hen,  why  they  are  in- 
ferior to  Goofe  Feathers,  i.  401 

Fecula,  i.  274 

Fell,  Mr  i.  507 

Felting,  Procefs  explained  by  Menge,  i.  401. 

Fergufon,  Mr.  ii.  123 

Fernandez,  Dominique  Garcia  de,  ii.  53 

Ferriar,  Dr.  ii.  188 

Figures,  ftrange,  feen  in  the  Air  and  the 
Sea,  i.  225.  Of  the  Earth,  ii.  39.  And 
Motions  of  the  Earth,  aneient  Opinions 
concerning,  ii.  184 

Files,  Machine  for  cutting,  ii.310 

Filtration,  by  Afcent,  ii.  356 

Fire,  Compofuion  for  Extinguifliing,  ii.  279 

. Arms,  Improvements  in,  i.  517.  Greek, 

Compofition  of,  ii.  90 

Fifli,  Eltflric,  Account  of  the  Organs  of,  i. 

357 
Fifhes*  Eye?,  Peculiarities  of  the  Struilurc 
of,  i.  47S,  547 

Filher» 


N 


D 


X. 


Fiflier,  Micrs,  ii.  191 

Flame,  L.  de  Vinci  on,  ii.  87.     Its  Effeft 

on  Eleftricity,  compared  with  that  of  a 

Point,  ii.  440 
Flangaques,  Cit.  ii/236 
Flangeroue,  I.  46 
Fleifchcr,  the  younger,  i.  48 
Fleetwood,  Bifliop,  ii.  284. 
Flexion  of  Light,  ii.  148 
Fkurieu,  Cit,  ii.  239 
Flies,  (mmcrfion  of  in  fermented  Liquors, 

FliM'.nnj;  Lamp,  ii.  167 
Fiujd,  Elaftic,  in  Air  Veflels  of  Fifli,  i.  264 
Fluids,  F.lafiic,  Laws  of,  rheir  Dilatability,  i. 
143.   Propagation  of  Heat  in,  and  general 
Confequences,  by  Count  Rumford,  i.  289, 
341,  %(>2.     Principle  of  the  lateral  Com- 
munication of  Motion  in  (Sec  Venturis, 
i.  524.      Method  of  meafuring  their  con- 
dutting  Powers,  i.  292.      Non-Conduc- 
tors  of  Heat,  ii.  160.     Lateral  Communi- 
cation of  the  Motion  of,  ii.  88.  273,  422, 
487 
Foil,  beautiful  Jewellers',  ii.  355 
Fontenelle,  ii.  428 
F'ordyc^-.  Dr.  George,  i.  65 
Forfier,  Dr.  i.  108.     Mr.  ii.  134 
Fortificaiion,  ii.   89 
Foni-.  Abbe  Alberto,  ii.  220 
Foffil  Bones  of  Gibraltar,  ii.  220 
Foulds,  John,  ii.  96 

Fourcicy  and  Vauquelin  on  Sulphureous 
Acid,  i.  313,  364.  On  Ether,  i.  3S5.  Ex- 
periments on  various  Detonations,  i.-i68 

<•  46,  49>  95>  "43.  >53.  '68,  177, 

205,  265,  275,  316,  335,  359,  363,444, 
535,  &c.  ii.  71,  97,  204,  209,  297,  414 
Fowls,  remarkable  Growth  of  their  Bones 
by  feeding  on  Phofphat  of  Lime,  i.  201 
France,  New  Syftemofthe  Weights  of,  i. 
197.  Table  of  Meafures  of,  and  Com- 
parifoa  with  Englifli,  i.  332 

Coaftof,  rendered  uncommonly  vi- 

lible,  ii.  418 
Frankland,  Sir  Thomas,  Bart,  on  the  Weld- 
ing of  Caft  Steel,  i.  575. 
Franklin,  Dr.  i.  396,  416,  433,  ii.  S09.  On 

Drowned  Flies,  11,353 
Franzaroli,  M.  ii.  356 
Free  Efcapements,  ii.  1:4 
Frec/ini;  Procefils,  i.  497,  568.  At  the  Bot- 
tom of  Water,  li.   163 
French  Republic,  Sale  of  Italian  Paintings, 
ice.  ii.  94.    Weights  and  Meafures,  com- 
parative Tables  with  Englifli,  ii.  2S4 
Frczier,  ii.  90. 

Friftion,  on  the  Heat  excited  by,  ii.   ic6 
Frifichius  Joachim,  on  Univerfal  Language, 

ii.  345 
Fryc,  Capt.  li.  315 
Fulhamc,  Mrs.  i.  486 
Fulminating  Gold  and  Silver,  i.  296 
Fuhninations,  very  lirong  with  Phol'phorus, 

by  Brugnatelli,  ii.  46S 
Furnace,  Lamp,  iu  210 
Fiifi^n  of  Earths,  i.   142 
Fufibility  of  Tallow,  Wax,  and   other  Ar- 
ticks,  i.  70 

G. 

GafTron.  M.  ii.  J^fi 

Vol.  IJ. — June   1799. 


Galen,  ii.  137 

Galileo,   ii.   88,   128.     On  the  Pendulum, 

''•.5' 
Gallic  Acid,  i.  274 

Gallitzin,  Prince,   i.  144 

Galls,  Acid  of,  ii.  338 

Galvanic  Irritation,  Effcft  on  Wounds,  i.  256 

Galvaniftn,  Publications  on,  i.  335 

GarciiafTo,  i.  107 

Garnerin,  his  Parachute,  i.  1:23.  His  Afcent 
into  the  Atmolphere,  ii.  377 

Garnicr,  Cit.  i.  96. 

Garrow,  Mr.  his  Hiftory  of  the  Corundum 
Stone,  ii.  4S0 

Gas,  Carbonited,  Hydrogeneous,  i.  44.  Ex- 
periments on,  by  Mr.  Henry,  ii.  241. 
Carbonated,  Oily,  Hydrogeneous,  i.  49. 
defiant,  i.  44.  Carbonated,  Hydroge- 
neous, obtained  from  Ether,  i.  52.  Car. 
bonated,  Hydrogeneous,  obtained  from 
Alcohol,  i.  52.  Okfiant  Qu^efiions  rela- 
tive thereto,  i.  53.  Oxygen  in  the  Air 
Veflels  of  Fifli,  i.  264.  Produced  from 
Water,  Nature  of,  i.  248.  Hydrogen, 
Apparatus  for  producing  Water  from,  ii. 
235.  Oxygen,  Apparatus  for  difengaging, 
by  J.  Sadler,  Efq,  ii.  33.  Sulphurated, 
Hydrogeneous,  ii.  71 

Gafparis,  Profeffor,  i.  48 

Gafl'endi,  ii.  84 

Gaultier,  Cit.  ii.  305 

Geographical  Defcription  of  North  America, 
by  J.  Rennel,  Efq.  ii.  253 

Geography,  Modern,  i.  48 

Geological  Obfervations  on  North  Wales,  by 
A.  Aikin,  i.  220 

Gcorgi,  Francis,  ii.  89. 

Georgium  Sidus,  Satellites  of,  ii.  240 

Georgius  on  Lemon  Juice,  ii.  43 

Gerard,  Dr.  i.  286 

German  Steel,  ii.  64 

Gcufs,  ii.  89 

Gibbes,  G.S.  Dr.  on  Sulphate  of  Strontian, 
ii.  535 

Gibrrr,  Cit.  ii.  237 

Gibraltar,  Mineralogical  Defcription  of,  ii. 
1S5,  219.     Diamonds,  ii.  187 

Gilpin,  Mr.  i.   117 

Giobert,  ii.  71 

Girtanner,  i.  363.  ii.  9 

Gifljorne,  Rev.  Tho.  ii.  1S9,  336 

Glafs,  Flint,  i.  i.  Optical,  Examination  of, 
i.  iSi.     Engraving  on  for  Printing,  ii.  60 

Glauber's  Salt  feparated  from  Salt  Water,  ijy 
Gren,  ii.  91 

Globules  fjr  Microfcopes,  i.  134 

Glucine  Earth,  ii.  359.     Chara£tcrs  of,  ii. 

395 

Glue  rendered  folid  by  Tan,  i.  277 

Godekir.g,  i.   100 

Godfrey,  Mr.  i.  299 

Gocttling,  i.  444.  ii.  8,  132 

Golbornt,  Mr.  ii.  95 

Gold  Leaf,  itsThicknefs, i.  133.  Dutch,  in 
Leaves,  i.  133.  Efteft  of  the  Mixture  of 
with  Tin,  ii.  140.  179.  Fulminating  Ex- 
periments, and  ObfcrvatioDb  on,  i,  206. 
Aftion  of  Niire  on,  li.  30.  Mine,  Account 
of  tile  Difcoveiy  of,  in  Irclsnt',  li.  223. 
Mot.ey,  ii.  i5o.  Whole  Qnaniiiy  in  Cir- 
cula;i  m,  ii.  2i'i4 

Golklin,  Cil.  1.  46.   ii.  2j3 


SS7 

Gottllng,  i.  142 

Gough,  Mr.  John,  on  the  Variety  of  Voicei, 
ii.  iS8.  On  the  fuppofed  Revival  of 
drowned  InfeSs,  ii.  353 

Gourdain,  Mr.  ii.  53. 

Gouvenain,  Cit.  i.  117 

Governor  for  regulating  the  Motions  of 
Steam  Engines,  ii.  46 

Graham,  George,  i.  58.  ii.   53,  224 

Granulation  of  Shot,  Procefs  of,  i.  263 

Gratcloup,  Mr.  ii.  233 

Gravefande,  ii.  179 

Gravimcter,  Defcription,  i.  no 

Gravitation,  Experiments  on  its  force  bcT 
tween  fmall  Bodies,  ii.  446. 

Gravity,  fpecific.  Table  of  that  of  commcn 
Salt,'  i.  192.  Inftrument  for  determin- 
ing the  fpecific,  of  Bodies,  i.  no.  ii.  84. 
Opinion  of  the  Ancients  on,  ii.  184 

Gray,  Stephen,  i.  396 

Greek  Fire,  Compofition  of,  ii.  90 

Gren,  M.  i.  117,  256.  On  the  Purifica- 
tion of  Salt  Water  by  Cold,  ii.  91 

Greville,  Mr.  i.  519 

Right  Hon.  Ch.  Efq.  F.R.S.  ii.. 

96.  His  Memoir  on  the  Corundum 
Stone,  ii.  477,  536 

Gridiron  Pendulum,  i.  59 

GrieffeBhag,  Andrew  Miller,  his  Cle  ChU 
noife,  ii.  346 

Grimaldo,  i.   555 

Grinding,  Method  of  preventing  its  He»t, 
i.   131 

Ground  Ice,  Theory  of,  ii.  164 

Grundy,  Mr.  ii.  95 

Guericke,  Otto,  i.  129 

Guiana,  Natural  Hiftory  of,  by  Mr.  Loc- 
head,  Efq.  ii.  297,  347 

Gulielmini,  J.  B.  his  Experimental  Proof 
of  the  Earth's  Rotation,  ii.  177 

Gum,  Analyfis  of,  by  Cruickfliank,  i.  406 

Gunpowder,  Prefervation  of,  i.  262.  Com- 
buftion  of,  in  a  clofed  Veflfel,  i.  459. 
Exp!:riments  to  determine  the  Force  of, 
by  Count  Rumford,  i.  459.  Rtfidue  of, 
burned  in  a  clofed  VefiU,  i.  464.  Prodi- 
gious Force  of,  i.  466.  Eftimate  and 
"Table  of  its  Force,  i.  467.  Combuftion 
of,  Progrcflive,  not  Inftantaneous,  i.  ^15. 
Method   of   improving  the  Effects  of,  i. 

517 

Gunter's  Scale,  improved  by  a  great  En. 
largcment  of  the  Divifions,  i.  372.  Spiral, 
i.  375.  Improvements  m  the  Ufe  of,  i, 
450 

Guthrie,  Matthew,  M.D.  on  the  Perfian 
Cotton  Tree,  ii.455 

Guyjot,  Cit.  i.  534 

Guyton,  i.  46,  95,  110,118,  142,  335.2-39. 
250,268,  540,  543.  ii-  43.  101,.  1  =  5. 
Laboratory,  ii.  209,  S14,  236.  On  chemi- 
cal Saturation,  li.  340.     Charcoal,  ii.  499 


H. 


Ha.is.  ii.  29,  236 
Hn(!ley,  ii.  1  28 

Hidicy's    Quadrant    uftfully   cmplovcd   to 
Meafurc  tlie  IvJ'raiStivc  Power  of   Fiuids, 

>•  3 
ll:;:.,   1.  SOI 


4  D 


Ha  dii)ger, 


ss^ 


I 


N 


D 


X. 


Haidinger,  M.  i.  404.  ii.  76 
Haighton,  John,  M.D.  on  Aaitnal  Impreg- 
nation, i.  191 
Hair,  Nature  and  Texture  of,  1.400.  Balls 

in  tlic  Stomach  of  Animals,  i.  401 
Haldane,  Col.  Ne"-  Method  of  Meafuring 

the  Fijrce  of  an  Eloflrical  Battery,  i.  156. 

On  Lightni.ig,  i.  433 
Hall,  Sir  James,  Bart.   F.R.S.  and   A  S.S. 

Edin.    on    the   Origin  and   Principle   of 

Gothic  Architefturc,  ii.  192 
Hall.W.  Efq.  his  Account  of  a  fingulaf  Halo 

of  the  Moon,  ii.  485 
Haile,  i.  174,  ioj 
Haller,  i.  305,  477.  ii.  72 
Halley,  ii.  85 

Halo,  finguiar,  of  the  Moon,  11.485 
Hamilton,  Dr.  i.  32 

Mr.  1.  146 

Sir  William,  i.jjo 

. Duke  of,  i.  (177 

Reverend,  Mr.  on  the  Climate  of 

Ireland,  ii.  3S  i,  43  i 

Hanbury,  ii.  334 

Hardnei's  and  Tenacity  in  Steel  are  diftinft 
Qualities,  i.  3S1 

Harmony,  Trcatifc  on,  i.  48 

Harrifun,  Mr.  John,  i.  59 

Hartley,  Mr.  on  the  Temper  of  Steel,  i.  382 

Harp  Eolian,  Defcription  of,  ii.  12 

Harris,  ii.  122 

Hafienfratz,  ?4r.  ii.  209 

Hatchctt,  Charles,  Efq.  F.R.S.  i.  54  5.  On 
the  Elaftic  Bitumen,  ii.  201,  248.  On 
the  Sydney  Earth,  ii.  143 

Hats,  Improvement  in  the  Manufafture  of, 
i.  399.     Manufa^ure of,  ii.  467,  509 

Hatton,  his  Univerl'al  Meafure,  i.  65 

Haukfbee,  i.  306 

Hauy,  ii.  415. 

Heat,  Prise  Medal  for  Difcoveries  on,  i. 
18S.  Its  Propagation  in  Fluids,  by 
Count  Rumford,  i.  289,  341,  563.  La- 
tent, (hewn  by  the  Recovery  of  Ignition, 
i.  38 1.  Of  the  Globe,  equalized  by  VVater, 
i.  567-  Excited  by  Friftion,  by  Count 
Rumford,  ii.  106.  Contents  of  Count 
Rumford's  Seventh  Eflay  on  the  Propaga- 
tion uf,  ii.  143.  Experiments  on,  by 
Count  Rumford,  ii.  160.  Fluids  arc  Non- 
Conduftors  of,  ii.  160.  Intenfe,  though 
not  perceptible,  ii.  166.  For  Chemical 
Expctiments,  economical  Mode  of  ob- 
taining, ii.  209.  Obfervations  on,ii.  397. 
Dr.  Parr's  Theory  of,  ii.  547 

Hecht,  L.  i.  53.  ii.  37* 

HcUins,  Rev.  Ji.hn,  F.R.S.  on  the  Compu- 
tation of  a  flowly  Converging  Series,  ii.  r43 

Henry,  Mr.  William,  on  Carbon,  ii.  141 

Hcraclides,  ii.  185 

Herbclot,  ii.  256 

Hergifweil,  Cold  Caves  of,  1.251 

HermbftsEdt,  M.  i.  519 

Hero,  Pneumatics  of,  li.  1J7 

Herodotus,  ii.  256 

Herrera,  i.  108 

Herfchell,  William,  on'the  Satellites  of  the 
Georgium  Sidus,  ii,  iz2,  142,  240 

Hcrz,  Mr.  i.  361 

Hefychius,  ii.  16 

Hicdcnburg,  on  Polynomials,  i.  47 


Hi  elm,  i.  496 

Hijrgins,  Br.  M.D.  on  FuhiiuicLting  Gold 
and  Silver,  i.  196.  ii.  246 

Hildebrandt,  M.G.F.  Elements  of  Che- 
miilry,  i.  239 

Hiftory  of  Sugar,  ii.  i?6 

7 —  Narural,  of  Guiana,  ii,  297,  347- 

Holiaiul,  Philemon,  ii,  JS4 

Holme,  Dr.  on  the  Invtrfe  Method  of  Cen- 
tral Forces,  ii.  iqo 

Home,  Everard,  Dc.  i.  191,  308,474,  548, 

55° 
Honey,  ii.  409 
Hooke,  Robert,  ii.    51.      His  Experimental 

Proof  of  the  Earth's  Rotation,  ii.  84,  88, 

312,  3>9'346 
Hnpc,  Dr.  i.  519,  530,   537.  ii.    192,  213, 

2ti7 

Hopkinfon,   i.  13 

Hopfon,  Dr.  ii.  514 

Horn,  Subfliture  for,  ii.  412 

Horils,  their  Power,'  ii.  4O6 

Hurcou's  Rule,  i.  452 

Horizontal  Refraftion,  ftrange  Appearances 

of,  i.  146.     Elcapement,  ii.  53 
Hoffack,  Dr.  on  Vifion,  i.  308 
Houghton,  Major,  ii.  28 1 
Houillt,  i.  2  to 
Howard,  W.  i.  431 
Hoyle,  M.  Thomas,  jun.  on  the  Oxygenated 

Muriate  of  Potafh,  ii.  290 
HubcTt,  Cit.  ii.  95 
Huddart,  on  Horizontal  Refraftors,  i.  146, 

igr,   227-  ii.  47,  96 
Hughes,  Rev.  Mr.  ii.  367 
Humboldt  on  Galvanic  Imitation,    i,   256, 

335.  3<'3 

Hume,  Dr.  ii.  289 

Hungarian  Bread,  i.  267 

Hungary.  Travels  in,  i.  95 

Hunter,  John,  Mr.  i.  308,   310,  357 

Huntfman's  Steel,  i.  576 

Hufard,  Cit.  i.  239,  529 

Hutton,  Dr.  ii.  285 

Huvghtns,  i.  i,  8,  57,  541.  ii.  40.  On  the 
Pendulum,  ii.  51 

Hydraulic  Phenomena,  ii.  422 

Hydrogen  carbonated,  i.  44,  49.  Gas,  Ap- 
paratus for  producing  Water  from,  ii.  235 

Hvdrogtn,  Propofal  to  fubftitute  the  Term 
Phlogifton  for,  i.  481 

Hydrogeneous  Gas,  Experiments  on  Car- 
bonated, by  Mr.  Henry,  ii.  241 

Hydrometer,  i.  iii.  ofBaume,  i.  37 

Hydroftatic  Prefj  of  Bramah,  i.  29 

Hygrometry,  i.  511 

I. 

Ibn  Al,  Wardi,  ii.  256 

Ice,  flow  Fufioa   of,   at  the  Bottom   of  a 

Veffel  of  boiling  Water,  i.  343 

Fufion  of,  by  Water,  i.  563 

Ground,  Phenomena  of,  ii.  164 

Iceland,  Cryftal,  ii.  153,   198 

Ignition  fuddcnly  incrcafed  by  latent  Heat, 

i.  382 
Immerfion  of  Infc£ls  in  fermented  Liquors, 

ii-  3  53 
Imrie,    Major,  his  Defcription  of  Gibraltar, 
ii.  i8j,  19;,  219 


Inflammation  of  combutllble   Subftances  by 

Kriftion,  ii.  292 
Inflexion  of  Light,  i.   13,  58(1,  5:1 
Jngenhouti,  Dr.  i.  83.  ii.  420 
Inlcfts,  fuj-pofcd  revival  of,  after  Inimfrfion 

in  fermented  Liquors,  i'.  3^3 
Inftitiition  for  iDcclianical  Ir.ii-rgvciTients,  i. 

55' 
Inftiument,  new  eleftrical  condcnfing,  i.   16 

New  Weather,  ii.    11.     For  E.uling,  ii, 

429 
Inteiility  of  Sounds,  i.  413 
Inventions,  Difficulties  attending,  i.  20.  H6\v 

far  thuy  ought  to  be  public  Property,  i, 

400.      Chemical  and    Mechanical,    their 

Charadfers,  ii.  309 
Ireland,  Change  of  Climate  in,  its. Caufes, 

ii.  381.     Gold  Mine  in,  ii.  213 
Iris,  artificial,   for  Improvement  of   Tele- 

fcopes,  i.  180 
Irritation,  Galvanic  Effeft  of,   on  Wounds, 

i.  256 
Iron,  Method  of  feparating  it  from  Man- 

gancle,  i.   210.     Procefs  for  difcovering 

Phofphorus   in,    i.    254.     Sitlphates    of, 

Oxidcd     ill    various    Degrees,     i.     453. 

Prulllates   of.    White   and   Blue,  i.   454. 

Eafy   Teft    of   its    Uniformity,    i.    470. 

Method    of  welding,  with  Call  Steel,  i. 

575.     Bar,    Procefs   for  making,  ii.   65. 

Combuftibility  of,  ii.  64.     Crude,  faid  to 

have  been  rendered  Malleable  as  it  came 

out  of  the  Mould,  ii.  356.     Oak,  ji.  335. 

Ore,  Argillaceous,  ii.  498 
Ifaiah,  Sugar  mentioned  in,  ii.  136 
Ifidorus,  ii.  16,  135 
Ivory,  James,  A.M.  new  Series  for  the  Rcc« 

tiiication  of  the  Ellipfis,  ii.  192 
Irvine,  Dr.  i.  286,  289 

J- 

Jaeger,  Dr.  ii.  9 

Jamcfon,  Dr.  i.  286 

Jars,  ii.  70,   102 

Jars,  Mr.  i.  496 

Jeremiah,  Sugar  mentioned  in,  ii.  236 

Jeffop,  William,  Efq.  ii.  47,  95 

Jet,  ii.  204 

Jewellers'  Fail,  Beautiful,  ii.  355 

John,  II.  i.  109 

Jones,    William,  on  Geometry,  Sec.  i.  192 

Journal  des  Savans,  Account  of,  i.  44.  Po- 

lytechnique,  i.  93 
Juba,  i.  137 
Jupiter,  Inftrument  for  exhibiting  its  Moons, 

ii.  122 
Jurin,  Dr.  i.  305 
Juifieu,  Citizen,  ii.  306 


K. 


Kalm,  ii.  304 

Kant,  Mr.  ii.  347 

Keith,  Alexander,  Efq.  F.R.S.  and  F.A.S. 

Edin.  Defcription  of  a  new  Barometer,  ii. 

192 
Kennedy,    Dr.   on   Pumice   and   Lavas,  ii. 

289 
Kepler,  i.  305 

Kicr,  his  Steam-Engine,  i.  422 
Killingtr,  Mr.  i.  98 

Kircber, 


N 


D 


E        X. 


Kirchcr,  Athanafius,  i.  jj6 

Univerfal  Polygraph'*,  it.  345 

Kirchoft",  Mr.  his  new  Procels  for  making 

artificial  Cinnabar,  ii.   i 
Kirwan,  Mr.  i.  48,  335.     Carbon  in  Coil, 

i.   487.      Temperature,    i.  574.  ii.   203, 

20;,  jog,  340 
K-laprotli,  i.  77,   )oo,  144,  404,   519,  536, 

544.  ii.   73,  71''.   77.   289 
; ,  liis  Account   of  a   new   Metal- 
lic  Subftance,    denominated    Tellurium, 

ii.  37i 
,  his  Analyfis  of   Corundum,  ii. 

484 
Klcngel  on  Polynomials,  i.  47 
Klincock,  i.  396,  ii.  497 
Kolegarten,  Mr.  i.  97 
Kramp  on  Polynomials,'  i.  47 
Kuenh,  Charles  Gottlieb,  i.  48 
Kunckel,  i.  444.  ii.  133,  135 


Labat,  ii.  258 

Laboiat  ry,  Economical,  of  Gtiytoii,  ii.  210 

Labour,  Prices  of,  st  diftcrent  Period,  ii.  284 

La  Ctiapellf,  Cit.  Due.  i.  153 

LacaiUe,  i.  194 

Lacepede,  i.  46 

La  Combe,  C.  Diftionary  of  Fifhery,  i.  48 

Lacuee,  Cit.  ii.  238 

La  Grange,  i.  48;  Bouillon,  on  Camphoric 
Acid,  ii.  97.     On  Camphor,  ii.  157 

La  Hire,  i.  99 

Laidley,  Dr.  ii.  2S0 

Lake,  new  Procefs  for  obtaining  from  Ve- 
getables, ii.  155 

Lakes,  North  Weftern,  of  America,  ii.  315 

Lalande,  Cit.  i.  96.  ii.  173,  233,  239 

Lamarek,  Cit.  Dictionary  of  Botany,  i.  48. 
On  the  Pneumatic  Theory,  i.  96 

ii.  236 

Lamhe,  William,  M.A.  Analyfis  of  the 
Waters  of  two  Mineral  Springs,  ii.  190 

Lamethrie,  Dr.  ii.  39 

Lamps,  i.  67.  Lampof  Argand.i.  69.  Float- 
ing, ii.  167.  Economically  ufed  for  Ex- 
periments in  Chemiftry,  ii.  210.  Self, 
moving,  ii.  167 

Lampsdius,  ProfefTor,  i.  142.  ii.  10 

Land  Culture,  i.  47 

Landen,  Mr.  i.  541 

Landriani,  M.  ii.  245 

Langlc,  H.  F.M.  en  Harmony  and  Modu- 
lation, i.  48    ' 

Langlts,  Cit.  ii.  236 

Language,  Univerlal,  ii.  189,  190,  342,  428 

Lar.thorns,  Wire  Cloth  for,  ii.  412 

Lapis  Lazuli,  Analyfis  of,  by  Klaproth, 
i.  77 

La  Place,  Mr.  Pierre  Simon.  His  Syftemof 
the  World,  ii.  39,  86,  236 

Laromiguicre,  i.  46 

Laffus,  Cit.  ii.  37,  236 

Latham,  William,  Efq.  on  a  lingular  In- 
ftance  of  Atmofpherical  Refrsftion,  ii.  417 

Launoy,  ii.  415 

Lauwerenberg,  i.  44 

Lava,  Examination  of  the  ftony  Charafler 
of,  ii.  285. 

Lavoifier,  i.  69,  168,  J78,  179,  237,  261, 
485,  487,  48»- 


La/ow&i,  Mr.  liis  new  Weather  Infirument, 
ir.  1 1 

Lead,  Siberian  Red,  ii.  3S7,  441 

Leather,  improved  Procefs  of  tanning,  i. 
271 

Leaves  of  Gold,  Silver,  and  other  Mttils, 
their  tiiicknefs,  i.  133 

Leboffut,  Cit.  ii.  236 

Le  lirun,  ii.  62 

Ltfevre,  Gineau,  Cit.  ii.  236,  239 

Leger,  M.  i.  69 

Le  Gran<;e,  Cit.  Bouillon,  his  Procefs  for 
purifying  Alkali,  i.  329 

Leibnitz,  ii.  71.  On  univerfal  Language, 
ii.  346,  428 

Le  Lievre,  M.  i.  40 

Lemons,  Preparation  of  the  concrete  Acid 
of,  ii.  43 

Le  Monnicr,  i.  99 

Lcr.ipE,  i.  142 

Lens,  Chryftaiine,  Obfervations  on  its  Struc- 
ture, i.  306 

Lenfis,  Achromatic,  fappcfed  Improvement 
of  cementing  them  together,  ii.  233 

Lent,  Adolph.  C.  M.D.'ii.  494 

Le  Roy,  Cit.  David,  i.  57.11.  239.  Mr.  ii. 
54.'  Peter,  i.  53 

Ltiburne,  Lord,  ii.  335 

Level  Spirit,  Defcription  and  Ufe  of,  i.  135 

Levelling,  eafy  Method  of,  ii.  467 

Lever,  Fundamental  Property  of  the,  i.  541 

Levcque,  i.  46 

Lewenhoek,  i.  308,  380 

Lewis,  Dr.  i.  486.  On  the  Trompe,  i.  526. 
ii.  31 

Lichtenbcrg,  i.  205,  396,  397 

Lichtenftein,  i.  228 

Life  of  Bcrtrand  Pelletier,  Account  of,  ii.  37 

Light,  RefraiStion  of,  i.  13.  Remarkably 
inflefted,  i.  13.  Economical  Prodiiftion 
of,  i.  67.  Of  Lamps  and  Candles,  Mea- 
fure  uf,  i.  67.  Prize  Medal  for  Difcove- 
rieson,  i.  1S8.  Its  Inflexion,  Flexion,  and 
Colour,  i.  551,  586.  Reflexion  of,  i.  554. 
Affcftions  and  Properties  of,  by  H. 
Brougham,  efq.  ii.  14-,  193.  Count  Rum- 
ford's  Enquiries  concerning  its  fuppofed 
Chemical  Properties,  ii.  402.  On  its  fup- 
pofed Clicmical  Properties,  ii.  4.53.  Dr. 
Parr's  Theory,  ii.  547.  Tranfmiliion 
and  Rcflcftion  of,  ii.  312.  Flexion  of,  ii. 
194.  Of  Natural  Phofphori,  ii.  132.  Ob- 
fervations on,  ii.  396. 

Lightning,  Obfervations  on,  by  Col.  Hal- 
dane,  i.  433.  Experiments  with  Arti- 
ficial, i.  436.  Eftefts  of,  on  a  Grove  of 
Trees,  i.  547. 

Ligurian  Irilitute,  ii.  522 

Linck,  Proftflbr,  ii.  71 

Linnaeus,  i.  26,  138.  ii.  155,  304,  333,  337 

Little,  Rev.  James,  Account  of  iiis  Air» 
pump,  ii.  501. 

Liver,  Prize  Queftions  on  the,  ii.  237 

Liverpool,  Earl  of,  i.«87 

Lloyd,  John,  efq.  F.R.S.  i.  96,  ii.  223 

Loans,  Public,  Prize  Q_ucftion  on,  ii.  238 

Lobchock,  or  Chinefe  Candle,  i.  72 

Lochtad,  William,  Efq.  on  the  Natural  Hif- 
tory  of  Guiana,  ii.  192,  297,  347 

Logarithms,  Theory  of  an  improved  Line 
of,  i.  372 

Longitude,  Prize  Q^eftion  on,  ii.  ^37 


S59 

Looming,  or   douWe  Land,  Appearance  of 

i.  IJ2.     Phenomenon  of.  ii.  548 
Lorinier,  Dr.   John,  his   Dipping    J^Jeed!e, 

i.  428 
Lotion.  Alkaline,  for 'promoting  the  Cure  of 

the  Rickets,  i.  20? 
Lowitz  on  the  Purification  of  Alkalis,  i.  164, 

331.11.3 
Lowry,  Mr.  ii.  524 
Lowthorpc,  i.  1 1 1 
Luc,  M.  de,  on  the  Contraflion  of  Water 

by  Cold,  i.  567 
Lucan,  ii.  137 
Luccomb,  ii.  335 
Luce,  Eau  de,  i.   80.     Compcfition  of,  and 

Experiments  on,  i.  166 
Luther,  Martin,  i.  109 

M. 

Machiavcl,  ii.  89 

Machine,  tUftric,  comparifon  between  Plates 
and  Cylinders  of  Glafs,  i.  83.  For  cut- 
'  ing  Files,  ii.  310.  Elcftrical,  by  Fric- 
tion of  Silk,  ii.  420.  For  ruling  Lints, 
ii.  429.  For  blowing  by  a  F.iil  of  Water, 
its  Theory,  ii.  48S 

Machines,  their  political  Eifefts,  ii.  460 

Mackay,  Andrew,  LL.D.  F.R.S.  Edin.  on 
the  Latitude  and  Longitude  of  Aberdeen, 
ii.  192 

Mackenzie,  Sir.  G.  S.  his  Air-pump,  ii, 
28 

Maclean,  i.  486 

Macpherlon,  Mr.  ii.  23 

Macquer,  i.  80,  i<J6,  488.  ii.  37 

Macquart,  Mr.  i.  457 

Magellan,  i.  75,  76,  loS 

Magnc,  J.  B.  i.  202 

Magiiefia,  Precipitai;ion  of,  i.  263.  Me* 
thod  of  fcparating  Argillaceous  Earth 
from,  ii.  83 

Magnetic  Polarity,  i.  97.  Touch,  Im^ 
provement  of  the  Double,  ii.  81 

Magnetifm,  Method  of  exciting,  ii.  8r 

Magnets,  artificial.  Method  of  making,  by 
Coulomb,  ii.  80 

Mahomet,  ii.  236 

Maleiherbes,  M.  Ic,  ii.  307 

Malting,  Experiments  on,  i.  338 

Mancheftcr,  Memoirs  of  the.  Literary  and 
Philofophical  Society  of,  ii.  188 

Manganefe,  Infufficiency  of  the  prefent  Me- 
thods to  feparate  it  from  Iron,  i.  255 

Manufafture   of  Hats,  Improvement  in,  i, 

399 
Maple  Sugar,  ii.  304 
Maraldi,  i.  99 
Mardonius,  ii.  319 
Marcorelle,  Mr.  i.  233 
Margraff,  i.  77.  ii.  31 
Margueron,  Citizen,  i.   182,  227,  404 
Mariana,  i.  1 10 
Mariner's  Compafs,  Account  of    the   Me, 

chanifm  for  the  Sufpenfion  of^  i.  426 
Mariotte,  ii.  177 
Mar,n,am,  Robert,  Efq.  F.R.S.  on  the  Mea.  ' 

lures  of  Trees,  i.  191 
Martin,  Benjamin,  ii.  199 
Maflcelyne,  ii.  85 
Mathematical  Correfpondence,  i.  45,  92,  137, 

138,  186,  188,  237,  238,  283,  284,  334, 

38*,  43» 

Mafhegiatics 


S6o 


N        D 


X. 


M.thcrnnt'cs,  Prizf  Qoeftion  in,  ii.  318 
M.Ujxrtuis,  M.  de,  on  Mulkai  Inftruments, 

i.  416 
Mayow,  ii.  88 

Mazeas,  Abbe,  i.  106,  51)7,  ii.  31? 
Meafures,  Table  of  French,  and  Compari- 

fon  with  ^"nj'ifli,  i.  193,  199,  331,  200, 

ii.  284 
Mechain,  i.  46 
Mechel,  J.  J.  de,  i.  95 
Medici  C<ifmo,  ii.  12S 
Melvill,  i.  -,85,  587 
Mcmieux,  Citizen,  ii.  342,  347 
!Mcn,  their  Mechanic  Power,  ii.  466 
Mcndoza,  Francifci,  i.  140 
Mercury,  its  Congelation,  i.  143 

Purification  of,  i.  i3i,  iSz 

Merfennus,  ii.  12,  344 

MeUier,  ii.  23* 

Metals,    their   Expanfions  by  Heat,  i.    58. 

Irritation   in  Wounds    produced    by,    i. 

Metallic  Bars,  Flexure  of  compound  by 
Change  of  Temperature,  i.  576.  Acid, 
new,  ii.  145 

Mcteorologv,  remarkable  Phenomenon  in, 
i.   511 

Methods  of  Priming,  i.  19 

Meyer,  iVlr.  i.  534 

Microfcopes,  eal'y  Method  of  forming  Glo- 
bules for,  i.  134 

Michau,  Cit.  ii.  30; 

M'chaud,  M.  on  Water  Spouts,  i.  577 

Michell,  the  Rev.  John,  his  Apparatus  for 
Mtafuring  Attraftion,  ii.  446 

Minazi,  i.  152 

Minafi  Antonio,  i.  225 

Mineral  from  New  South  Wales,  Analyti- 
cal Experiments  on,  i.  431;.  ii.  72 

Mineralogical  Defcription  of  Gibraltar,  ii, 
219 

Mines,  Difcovery  of  the  Wicklow  Gold,  ii. 
223 

Miller,  ii.  334 

Military  Architefture,  ii.  89 

Mills  Abraham,  Efq.  ii.  224 

Milne,  Robot,  Efq.   ii.  47,  96 

Milk,  Sugar  of,  ii.  409 

Miichill,  i.  481.  On  PhIogifton,i.  528.  Dr. 
On  an  Argillaceous  Iron-ore,  ii.  494 

Modulation,  i.  48 

Molard,  on  Pinions  of  Glafs,  ii.  1:22,  546 

Molefworth,  William,  Efq.  ii.  227 

,  Richard,  Efq.  F.R.S.  ii.  227. 

Money,  Origin  of  Metallic,  ii.  260.  Gold, 
accounts  of  the  Rccoinat;e  of,  and  aftual 
Q^^^ntity  in  Circulation,  ii.  264.  Depre- 
ciati^in  of  at  difteient  Periods,  ii.  284 

Ming.e,  Cit.  i.  46,  93,  209,  213 

on  felting,  i.  400.  u.  102,  105,  190, 

235,  245 

Mimro,  Dr.  i.  265 

Moon,  Speculations  on  its  Want  of  Water, 
ii.  87 

Morgana,  Fata,  account  of,  i.  2:5.  ii.  416 

Morocco,  Emperor  of,  ii.  25S 

Mwrton.  the  Right  Hon.  the  Earl  of,  F.R.S. 
ii.  96 

M"'ion  in  Fluids,  Pri.KipIc  of  the  lateral 
Cinimunicition  of,  i.  524.  Perpetual, 
accounts  of  variou,  Sciicmes  for  pro.tu- 
cing,  i.  334.  J75-     ^^ '^  Floating  Lamp, 


ii.  167.  In  Fluids,  lateral  Communicaion 
of,  ii.  273 

Morveau,  M.  de,  i.  39 

Mount  Perdu,  its  calcareous  Nature,  ii.  510 

Mountain  Magnetic,  i.  97. 

or  Mineral  Pitch,  ii.  203 

Mountains  of  Wales,  Pofition,  Figure,  and 
Strufture  of,  i.  220 

Mouffin  Poufchin,  Count  Apollos,  on  Cinna- 
bar made  in  the  humid  Way,  ii.  i 

Mouton,  i.  194 

Movers,  firft,  on  the  Meafure  and  Expence 
of,  ii.  459 

Mudge,  Capt.  i.  150,  198.  ii.  550.  Mr.  his 
Efcapement,  ii.  56 

Mulgrave,  Lord,  i.  572,  574 

Mullcr,  John.  i.  108.  ii.  372 

Murhard,  F.W.A.  on  Equations,!.  48 

Muriate  of  Potafli,  Oxygenated,  ii.  190.  Pre- 
paration and  remarkable  Properties  of  the 
Oxygenated,  ii.  290. 

Mufchenbroek,  i.  121,411,30;.  ii.  88,313 

Mufical  Inftrument,  Refonance  of,  i.  416 

Muffin,  Pufchkin,  Count,  011  Platina,  Co- 
balt, &c.  539 

N. 
Nairne,  Edw.  Mr.  ii.  420,  515 
Naptha,  ii.  202 

Naflau  Saarbruck,  Prince  of,  494 
Natural  Steel,  ii.  64.     Hiftorv  of  Guiana,  ii. 

^9">  347-     Philofophy,    Prize   Queftion 

in,  ii.  329.     Phofphori,  Light  of,  ii.  132 
Navarro,  Peter,  ii.  89 
Navigation,  Dangers  of,  in  the  Vicinity  of 

Scylla  and  Charybdis,  ii.  15 
Nearchuj,  ii.  136 
Negro,  remarkable  Change  of  Colour  in  a, 

ii.  191 
Nevill,  Jacob,  ii.  223 
Neutrality  of  Salts  by  Decompofition,  double 

interefting  Qncftion  concerning,  ii.  340 
Newcomen  and  Cawley,   Inventors  of  the 

Lever  Steam  Engine,  i.  422.  ii.  231 
Newton,  Sir  Ifaac,  i.  i,   15,  16,  152,  177, 

526,  541,  542,  552,  554,  558,  562,  5S9, 

593.  Syf"'  S^f'.    5^8,    590.    ii.    53,   m'«, 

152.  174,  195.     His  Fits  of  Tranl'miffion 

and  Refleftion  of  Light,  ii.  312 
Nickalls,  Mr.  ii.  95 
Nicola,  i.  47,  48 
Nitre,    New   Procefs    for   refining,    ii.    23. 

A6^ion  of  on  Gold  and  Platina,  ii.  30 
Nitrous  Acid,  Examination  of  the  Purity  of, 

ii.  119 
Noel,  i.  359 

Nollet,  i.  229,  231,  234,  411 
North  Africa,  Geceraphical  Defcription  of, 

by  J.  Rennel,  E(q.  ii.  2^3 
Northumberland,  Hugh,  Duke  of,  ii.  334 
North  Wales,  Geology  of,  i.  220 
Notlem,  Mr.  i.  334 

O. 

Oak  Bark,  foluble  Principles  of,  i.  273 
Oak  Iron,  Wainfcot  or  Turkev,  ii.  }}^ 
Obfervations,  geological,  on   Nor:h  Wales, 

i.  220. 
Odorant  Bodi':s.  Experiments  to  render  their 

Emanations  perctptible,  i.   i;?,43i 
Oil,  Form-.it'on  of,  i.   5;.     Its  Compounds 

with  Earths,  Alkalis,  and  Metals,  by  Bei- 


thollet,  i.  170.  Volatile,  their  Congela- 
tion by  Cold,  &c.  i.  182,  227.  Mdcufe 
of  for  tempering  Steel,  i.  382.  Purifi- 
cation of,  ii.  4t.  Extraftion  and  Purifica- 
tion of,  ii.  9'j.  Of  Vitriol,  Examinatioa 
of  the  Pu;ity  of,  ii.  ii8.  Motion  of 
a  floa-ing  Lamp  in,  ii.  167 
Oils,  Volatile,  their  Congelation   by  Cold, 

&C.    i.    182,    227 

Oli-fiant  Gas,  i.   44,  49 

Optical  Glafs,  Imperfeftions  of,  i.  181 

Optical  Appearance,  Account  of  Fata  Mor- 
gana, a  remarkable,  i.  225 

Ore  of  Tin,  Analyfis  of,  i.  544 

Orfyrcus,  M.  i.  376 

Oriental  Lapis  Lazuli,  Analyfis  of,  i.  77 

Ormond,  Earl  of,  iL  224 

Ofwald,  ii.  12 

Otto,  Mr.  on  the  Difcovery  of  America, 
i.  73.  '06.  107 

Overflowing  Well,  artificial,  ii.  276, 

Ovid,  ii.  20 

Oxendon,  Hcnrv,  Efq.  ii.  96 

Oxygenated  Muriate  of  Fotafli,  Preparation 
and  remarkrib;e  Properties  of,  ii.  290 

Oxvgen,  in  the  Bladders  of  Fife,  i.  264. 
Prouft  on  its  Tranfition,  ii.  515.  Gas, 
Apparatus  for  difengaging  of,  by  Sadler, 
ii.  33 


Page,  Sir  Thomas,  Knt.  F.R.S.  ii.  96 
Paintings,  Italian,  Sale  of   by  the  French 

Repuhlic,  ii.  94 
Pajot  dcs  Charmes,  ii.  427 
Pallas,  R.  on  Siberian  Red  Lead,  ii.  387 
Papaciii,  M.  i.  579 
Papin,    Dr.  his  Steam   Engine,  i.  421.  ii. 

228 
Papon,  Cit.  ii.  236 
Parachute,  Experiment  with,  by  Garnerin, 

i.  5:3 
Paraguatan,  a  new  dying  Wood,  i.  93 
Park,  Mr.    his  Travels  in   North   Africa, 

i.  253,  2S0,  329,  379 
Parker.  Mr.  ii.  267 

Parr,  M.D.  his  Theoryof  Light,  i.  351.  ii.547 
Partington,  Mr.  i.  397 
Pafi.^raphy,   ii.   342 
Pcailon,  G.  M.D.  on  the  Decompofition  of 

Water  by  Electric  Difcbarges,  i.  241,  299, 

349.  ii.  142,  235,  396 
Pcarfon,  Rev.  W.  on  Gunter's  Rule,  i.   450. 

His   Satellitian,   ii.   122.     His   Eleftrical 

Machine,  i.  506 
Peart,  E.  M.D.  on  Phyfiology,  i.  600 
Pclleticr,  i.   40,   160,    184,   518,   519,   529,  • 

53''>  53  7-     Account   of  the   Life  of,  ii. 

37,  4*7. 
Pelliam,  Right  Hon.   Thomas,  ii.  227 
Pembcrton,  Dr.  i.  305.   ii.  314 
Pendulum,  i.  57,  58,  59.  ii.  40.   Apparatus 

for  preventing  EfFefts  of  Cold   and   Heat 

on,  i.65.     Obfervations  on,  i.  429.  Firft 

Invention  of,  ii.  52 
Perception  of  Colours,  anomalojs  in  Mr. 

D.ilton,  ii.  18S 
Perp^tunl    Motion,   i.   334.      Accounts    of 

various  Sch.mes  fur  produc  ng,  i.  375 
Perrut,  ii.  103 

Pcrrole,  M.  Experiments  on  Sojnd,  :.  411 
I'errot,  Mr.  ii,  319 

Petrol 


I 


N 


D 


E 


X. 


5§K 


Petrol,  or  Petroleum,  ii.  tot 
Petroleum  induratum,  ii.  ioj 
Peyff  r,  i.  233 

Pfaflf,  Dr.  on  Polynom'als,  i.  47.   361,  ii.  9 
Phenomenon,  remarkable,  Optical,  i.  zi$ 
Philadelphia,  Chemical  Society  of,  ii.  376 
Philipps,  Samuel,  ii.  96 
Philolaub,  ii.  185 

Philolophical  Tranfaftions  of  the  Royal  So- 
ciety, i.  191.  ii.   142,  420-     Correfpand- 
ence,  i.  185,  528,  430,  431,     Society  of 
Manchefter,  IViemoirs  of,  ii.  188 
Phofphori,  Light  of  the.  Natural,  ii.  134 
Phofphoric  Acid  contained  in  the  Urine  of 
Animals   that   feed  on  Vegetables  only, 
ii.  71 
Phofphorus,   Combuftion   of,    in    vacuo,    i. 
236,  279.     Obftrvations  on,  and  Experi- 
ments with,  by  Brugnatelli,  i.  444.     Sup- 
po'ed   Apptarance    of    Light    in   Azotic 
Gas,  ii.  8.     Its  Combuftion,  ii.  498 
Photius,  ii.  136 
Picard,  i.  99 

Piftet,  ProfelTor,  i.  97.  ii.  i6o,  414 
Pinchbeck,  Mr.  i.  6i 
Pigotr,  Edward,  Efq,  on  the  Brightnefs  of 

two  fixed  Stars,  i.  191 
Pifo  Cneius,  ii.  254 

Pifton,  Metallic  of  Mr.  Cartwrighr,  ii.  364 
Pitch  Mountain,  or  Mineral,  ii.  203 
Pius  III.  Pope,  i.  75 
Planetary  Atmofpheres,  ii.  40 
Planets,  Motion  of,  ii.  41.     Inftrument  for 

exhibiting  Jupiter  and  Satellites,  ii.  122 

Plants,  Irritability  of  the  Pollen  of,  i.  471 

Platina,  Salts   and   Precipitates  of,   i.   537. 

Amalgam  of,  i.  53S.   Aftioa  of  Nitre  on, 

ii.  30 

Playfair,    John,    on     the    Trigonometrical 

Tables  of  the  Bramins,  ii.  167,   192 
Pliny,  i.  107,  137.  ii.  255,  256,  259 
Plumb  Line  and  Spirit  Ltvel,  i.  134 
Plutarch  on  Gravitation,  ii.  85,  184 
Polarity,  magnetic,  of  a  Mountain,  i.  97 
Poleni,  ii.  172 

Pollen  of  Plants,  Irritability  of,  i.  471 
Polybius,  ii.  238 
Polynomials,  i.  47 
Polytechnic  School,  i.  93,   141 
Poor,   report  of  Society  for  bettering  the 

Condition  of,  i.  190 
Poplar,  Athenian,  ii.  334 
Population  of  Europe,  ii.  436 
Porta  Baptifta,  ii.  90 
Portable  Eleftrical  Machine,  Defcription  of 

a  New,  i.  506 
Porterfield,  Dr.  i.  305 
Pot-afti,  Economical    Procefs  for  obtaining 
Pure,  i.  329.     In  Volcanic  Produftions, 
ii.  289 
Pott,  i.   142 

Poultry,  Pricesofat  different  Periods,  ii.  184 
Pound,  ii.  128 
Precipitates  of  Platina,  i.  537 
Prelong,  Cit.  i.82 
Preparation  of  the  oxygenated  Muriate  of 

Pot-afli,  ii.  290 
Prefs,  Hydroftatic  of  Bramah,  i.29 
Prefervation  of  Gun- powder,  Mode  of,  1,262 
Prevoft,  Benedift,  on  Odours,  i.  153 
Prevot,  Cit.  i.  97,  153,  154,  ao5,  431 
Vol.  I.  July  1799. 


Prices  of  various  Articles  at  different  Pe- 
riods, ii.  284 
Prieftley,    Dr.    i.  67,   182,  261,  265,  314, 

481,    5*7.    546-    !>•    95»    96,   i9<'>  i'9. 

243,  246,  313,  314 
Prieur,  i.  44.  ii.  262 
Piince,  Rev.  J.  his  Air-pump  defcribed,  i. 

121,  441.  ii.  29 
Printing  by  Cylinders,  i.   18.     From  Glafs 

Plates,  ii.  60 
Prints,  Method  of  Cleaning  and  Bleaching, 

ii.  26; 
P|rior,  Mr.  John,  his  new  Efcapement,  ii. 

363 

Prize  Donation  by  Count  Rumford,  i.  188 

Procefs  for  making  Artificial  Cinnabar,  li.  2. 
For  refining  of  Saltpetre,  ii.  23.  Of  Bleach- 
ing, ii.  268 

Projeflion  of  the  Earth,  ii.  39 

Prony,  i.  46,  420,  421.  ii.  173,  231 

Propagation  of  Sounds,  Experiments  on,  by 
Perrole,  i.  411.  Of  the  Zebia,  curious 
Faft,  relpe£ting  the,  ii.  z67. 

Properties  of  Light,  ii.  147,  194 

Proportional  CompaiTcs,  ii.  89 

Prouft,  i.  184.  On  Pruffian  Blue,  i.  453.  ii. 
97.  His  Memoir  on  the  Tanning  Prin- 
ciple, ii- 337.  339.  Enquiries  concerning 
Tin,  ii.  515 

Pruflian  Blue,  Enquiries  concerning  the  Na- 
ture of,  by  Prouft,  i.  453.  Folfil,  from 
B.razil,  ii.  508 

Prulfiates  of  Iron,  White  and  Blue,  i.  454 

rrulfic  Colouring  Principle,  i.  142. 

Ptolemy,  i.  107.  li.  238,  259 

Public  Loans,  Prize  Queftion  on,  ii.  238 

Pumice,  Analyfis  of,  ii.  289 

Pump,  Air,  i.  119.  New  Conftruftion  of,  i. 
441.  By  Sir  Georg'::  S.  Mackenzie,  ii. 
28.  Common,  i.  120.  Worked  by  the 
Wind,  rendered  fteady,  ii.  71 

Purification  of  fixed  Alkalis,  i.  164.  Of 
011,11.46.  Of  Water,  ii.  213.  Of  Mer- 
cury, i.  181.  Of  Potalh  economical  Pro- 
cefs for,  i.  329 

Purity  of  Drugs  and  Medicinei,  Examina- 
tion of,  ii.  118 

Putois,  Sieur,  ii.  233 

Pufchkin,  Count  Mufiin,  i.  537 

Pyrenean  Mountains,  the  moft  elevated 
Summit,  calcareous,  ii.  511 

Quadratic  Equations,  Rule  for  folving,  i. 

»39 

Queflion,  Philofophical,  i.  284.  Mathema- 
tical, i.  92,  138,  186,  188,  238,  284,  41 1 

Qulckfilver,  Method  of  Congelation  of,  by 
Walker,  ii.  497 

R. 

Raab,  Mademoifelle,  ii.  248 

Rachitis,  or  Rickets,  Nature  and  Treatment 

of,  i.  174,  200 
Rain,  preceded  by  Drynefs  of  the  Atraof- 

phere,  i.  51 1 
Rambouillet,  M.  ii.  308 
Ramond,  his  Excurfion  to  Mount  Perdu, 

ii.  510 
Kamuntiini)  Mr.  i.  328 


Ramfden,  Mr.  i.  310,  476.  His  Acco,un,t  qf 
Lenfes  Maftique^s,  ii.  96,  234,  42J 

Ranchon,  Mr.  i.  201 

Randel,  Ad.  FiiJ.  on  the  Powers  of  Euro- 
pean States,  i.  47 

Raflilcigh,  Philip,  M.P.  F.R.S.  and  F.A.S. 
Specimens  of  Minerals,  i.  96 

Rafpe,  Mr.  ii.  346 

Raw  Silk,  Bleaching,  i.  jit,  S8 

Read,  Mr.  John,  ii.  j63.  On  the  Doufaler, 
ii.495 

Reaumur,  i.  36.   ii.  T90,  2S6 

Red  Lead  of  Siberia,  new  Metallic  Acid  in> 

Reflection  of  Light,  i.  554.  ii.  148,  198 

Rcflcftors,  ii.  197 

Refraition,  Aiim^fpherical,  fingular  Inftance 
of,  by  W.  Latham,  Eliq.  ii.  41 7 

Refrafilion,  A(  hromatic,  by  a  fingle  Surface, 
i.  7.  Horizontal,  fingular  EfFedts  of,  i, 
146,  152.     Correftions  for,  i.  1 50 

Refraftive  Puwer  of  Fluids,  meafure  of,  i.  t 

Re-t'iomontanus,  i.  108.  ii.  84 

Rehe,  Mr.  ii.  421 

Re-id,  Dr.  on  Vifion,  i.  549 

Reil,  i.  255 

Renaud,  Mr.  i.  579 

Rennel,  James,  Elq.  F.R.S.  his  Obfervations 
on  North  Africa,  ii.  253,  280,  483,  350 

Rennie,  John,  efq.  ii.  47,  95 

Refonance  of  M'llical  Inftruments,  i.  416 

Revival  of  Infefts  after  Immerfion  in  fer- 
mented Liquors,  ii.  353 

Ribbands,  Count  Rumford's  Experiments 
on  the  Reduflion  of  Metallic  Oxyds,  at- 
tached to,  ii.  400 

Richmond,  Duke  of,  i.  377 

Richtcr,  Mr.  ii.  342 

Rickets,  or  Rachitis,  Nature  and  Treatment 
of,  i.  174,  200 

Rifled  Shot,  Experiments  with,  i.  382 

Rings,  Fairy,  i.  546 

Rinmann,  i.  77.  ii.  105 

Rios,  Don  Jofef  de  Mcndoza,  Refearches  ia 
Aftronomy,  i.  19 

Rittenhoufe,  David,  Efq.  i.  13,  152 

Rivard,  ii.  378 

Rivers,  Edtlies  of,  ii.  492 

Rivers  of  Guiana,  it.  348 

Robertlbn,  Dr.  i.  108.  Mr.  his  Gunter's 
Rule,  i.  374. 

Robifon,  Profcflbr,  ii.  199 

Robins,  Mr.  on  Gunpowder,  i.  459 

Rochon,  Abbe,  on  Achromatic  Lenfes,  ii.  23  J 
His  Wire-cloth  for  Lanthorns,  ii.  412 

Rock  Cryftal,  produced  in  the  humid  Way, 
by  Tromenfdorff,  i.  217 

Roebuck,  John,  M.D.  ii.  191 

Roederer,  Cit.  ii.  238 

Rollo,  Dr.  i.  285,  341.  ii.  427 

Rom6  de  L'lfle,  i.  25 

Romieu,  i.  153,  205,  2o5 

Roquefort,  Cold  Caves  of,  233 

Rofe  Water,  to  make  at  all  Seafons,  i.  80. 

Rofe,  Mr  ii.  372 

Rofeapcnna,  Manfion  of,  deftroyed|by  the 
Sands,  ii.  3S5 

Rotation  of  the  Earth,  ii.  39 

Rouelle,  ii.  71 

Rouland,  his  Silk-machine  for  Eleftrjcity,; 
ii.  420 

Rowley,  Mr.  ii.  12a 

A  £  Roy, 


562 


N 


D 


X. 


Roy,  General,  i.  i;i,  198 

Koyal  Society,  Donation  to,  i.  188 

Rozier,  ii.  134 

Rule,  Gunter's,  Improvements  in  the  Ufe 

of,  i.  450 
Rumford,  Count,  i.  67,  100.     On  Coloured 

Shadows,  i.  loi.     His  Prize  Donation,  i. 

j88.     Effiys,  i.    191,  238,  zzg.     On  the 

Propagation   of  Heat  in  Fluid?,  i.  289, 
'     341,  563.     On  the  Force  of  Gunpowder, 

i.  4^9.  ii.  85.     Of  an  Heat   excited  by 

Friftion,    ii.     io6,    141.      Contents    of 
■     his  Effay  VII.   on    the   Propagation   of 

Heat  in  Fluids,   ii.   143.     On    Heat,    ii. 

160.     His  Effays,  ii.  377.     On  the  fup- 

pofed  Chemical  Properties  of  Light,  ii. 

400,  453 
Rupp.Theophilus  Lewis,  on  Phlogifton,  &c. 

ii.  190.     On  Bleaching,  ii.  268 
Ruffian  Empire,  Statiftical  View  of,  ii.  47 
Rufti,  Dr.  Benjamin,  Account  of  the  Sugar 

Maple,  ii.  308 
Rutherford,  Dr.  ii.  29 


Saccharinum  (Acer),!!.  304 

Sadler,  James,  Efq.  i.  44  j.  His  Air-pump, 
ii.  30.  His  Furnace  for  Oxygen,  ii.  33. 
Defcription  of  his  Steam-engine,  ii. 
228,  231. 

Sage,  Mr.  i.  494.     B.  G.  ii.  31 

Sale  of  Paintings  in  Italy,  i.  '94 

Salmalius,  i.  137 

Salt,  Common,  Table  of  the  Specific  Gra- 
vity, of,  i.  192 

Saltpetre,  new  and  fpecdy  Procefs  for  Re- 
fining, by  Chaptal,  Champy,  and  Bou- 
jour,  ii.  23 

Saltonftall,  Winthorp,  on  Septon,  or  Azote, 
i.  240 

Salt,  obtained  without  Artificial  Heat,  ii.  72. 
Of  Platina,  i.  537.  Method  of  Purify'ng 
by  Cold,  ii.  9 1 

Sahs,  on  the  Tables  of  the  Compofition  of, 
ii.  340 

Sanftoriuson  the  Pendulum,  ii.  51 

San  Michel,  ii.  89 

Santus  Marinus,  i.  139 

Sarafin,  Mr.  ii.  304 

Satellites,  Inftrument  for  Exhibiting  Jupi- 
ter's, ii.  122.  Of  the  Georgium  Sidus, 
ii.  240     " 

Satellitian,  or  Inftrument  for  explaining  the 
'  Phenomena  of  Jupiter  and  his  Satellites, 
by  Mr.  Pearfon,  ii.  122 

SauITure,  i.  220,  571.  On  the  cold  Winds 
which  iOTiie  Out  of  the  Earth,  i.  229 

Savannahs  of  Guiana,  ii.  303,  347. 

Savery,  Captain,  falfely  accufed  of  pirat- 
ing the  Marquis  of  W'orCefter's  Steam- 
engine,  i.  419 

Say,  H.  his  New  Method  of  determining 
Specific  Gravity,  i.  325 

Scarpa,  i.  256,  257 

Schalleru,  Dr.  i.  257 

Schedl,  Hartfman,  i.  75 

Schceie,  i.   141,  268,  320.   ii.  37,  43,  91, 

133.  i68- 
Scherer,  Mr.  i.  242 
■  Scheiner,  Remark  on  his  famous  Obferva- 

tion  of  an  Hilo,  at  Rome,  ii.  487 
Scherer,  Dr.  Alexander  Nicholas,  on  Phof. 

phorus  in  Ajute,  ii.  S 


Schoner,  ii.  84 

Schmeifier,  M.  i.  519 

School  Polytechnic,  i.  93,  141 

Scintillation  of  the  Stars,  ii.  85 

Scotus,  i.  226 

Screw,  on  its  Mechanical  Conftruflion  and 
Ufes,  i.  158 

Scylla,  Defcription  of,  ii.  12 

Sea  Sicknefs,  cure  of,  i.  82.  Encroachment 
on  the  Coaft  of  Wales,  i.  224.  Hot  and 
cold  Currents,  i.  573.  Effeft  of  the  Sun's 
Heat  upon,  ii.  15 

Segum,  i.  26,  46,  271.  ii.  339 

Sentbier,  i.  48.     On  Water-fpouts,  i.  577 

Seneca,  ii.  137 

Serpentine,  Magnetic  Mountain  of,  i.  97 

S'Gravefande,  i.  111,  376 

Shadows,  Coloured,  their  Caufe  and  Eflfefls, 
i.  181 

Shaw,  Dr.  ii.  250 

Sheep  caufcd  the  Difcovery  of  cold  Caves  in 
Switzerland,  i.  23  i 

Sheldrake,  T.  on  the  Club-foot,  ii.  144 

Shiviers,  Dr.  Conrad,  his  Perpetual  Mo- 
tion, i.  378 

Shot,  patent  Manufafture  of,  i.  263.  Rifled, 
Experiments  made  with,  i.  382 

Shiickburgh  Evelyn,  Sir  George  A.  Bart. 
F.R.S.  and  A.S.  ii.  96.  On  a  Standard 
for  Weight  and  Meaiure,  ii.  143 

Siberian  Red-lead,  New  Metallic  Acid  in, 
ii.  145,  441 

Siegling,  Profeffor,  i.  335 

Sight,  Imperfeftions  of,  i.  549 

Silk,  Raw,  Bleaching  of,  i.  32,  88.  Procefs 
for  dying  Yellow,  f.  92 

Silver  Lea^  its  Tliicknefs,  i.  133.  Fulmi- 
nating, Experiments,  and  Obfervations  on, 
i.  296.  Unfuccefsful  Experiments  to  al- 
loy it  with  crude  Platina,  i.  380.  Mo- 
nies, ii,  260 

Simmer,  i.  396 

Simpfon,  W.  i.  138,  334 

Sinclair,  Sir  John,  ii.  357 

Smeaton,  Mr.  John,  F.R.S.  i.  »2i,  122, 
Reports,  ii,  47,  95.     On  Mills,  ii.  461 

Smith,  Mr.  Pearce,  i.  472.     Dr.  ii.  284 

Smoke,  ii.  87 

Soap  cf  Wool,  Experiments  on,  i.  40,  81. 
Earthy  and  Metallic,  by  Berthollet,  i.  170. 
Decompofition  of,  i.  171,  540.  Antimo- 
nial,  i.  540 

Society  of  Natural  Hiftory  of  Paris,  i.  24. 
American  Philofophical,  ii.  376.  Che- 
mical, of  Philadelphia,  ii.  376.  Of  Civil 
Engineers,  Origin  of,  ii.  47.  Of  Civil 
Engineers,  ii.  95.  Of  Civil  Engineers, 
Members  of,  ii.  96.  Of  Edinburgh, 
Tranfaflions  of,  ii.  191.  Philofophical, 
of  Manchefter,  Memoirs  of,  ii.  188 

Soda,  fuperlaturated  Borate  of,  luminous 
Quality  of,  ii.  28.  Separation  cf  the  Sul- 
phate of,  from  Salt-water,  ii.  91.  In 
Volcanic  Produftions,  ii.  289 

Solar  Spectrum,  i.  15 

Soller,  Cit.  i.  21 1 

Sound,  Experinncnts  on  the  Propagation  of, 
by  Perrole,  i.  411.  Intenfity  of,  i.  413. 
Inftruments  for  conveying  Obfervations 
on,  i.  417.  Remarkable  Phenomenon  cf, 
obferved  by  the  Aeronaut  Garnerin,  ii. 
377.  Varieties  of  the  fame  Tone,  ii.  188 


Spallanzani,  Abb^  Laiaro,  Profeffor,  F.R.S. 
&c.  Travels  in  the  Two  Sicilies,  &c.  i. 
48,  363,  600,  On  Scylla  and  Charybdis, 
ii,  12,  no 

Specific  Gravities,  Tables  of,  i.  1 17, 118,  119 

Specification,  of  a  new  Method  of  Tanning, 
i.  26 

Speftrum,  Solar,  of  uncommon  Brilliancy, 
i,  15 

Specula,  Metallic,  afford  Colours  by  Flexion 
and  Rcfleftion,  ii,  153,  197 

Spencer,  Earl,  his  famous  Well,  ii.  25; 

Spirit  Level,  and  Plumb-line,  compared, 
i.  134 

Spouts,  Water,  Account  of  the  Appearance 
of,  by  Michaud,  i.  577 

Squinting,  i.  549 

Stahl,  i.  363,  485.  ii.  43 

Stars,  Scintillation  of,  ii.  8; 

Statics,  ii.  88 

Statins,  i.  137 

Steam-engine,  Defcription  of  Capt.  Savary's, 
i.  419.  Defcription  of  Mr.  Kier's,  i. 
422.  Prize  Queftion  on  the  Heat  of,  ii. 
329.  Governor  for  regulating  the  Mo- 
tions of,  ii.  46.  Working  by  a  Pifton, 
Account  of,  ii.  228.  Boulton  and  Watt's, 
ii.  230.     Sadler's,  ii.  231 

Steam,  Betancour's,  Experiments  on,  i.  518 

Steel,  New  Analyfis  of,  by  Vauquclin,  i.  2 10, 
214,  268.  Method  of  feparating  it  from 
Manganefe,  i,  216.  Tables  of  its  component 
Parts,  i.  251.  Procefs  for  difcoveriiig  of 
Phofphorus  in,  i,  254.  Styrian,  i,  328. 
Mode  of  Hardening  and  Tempering  of,  i, 
381.  Imitation  of  Damafcus,  i.  469, 
Eafy  Teft  of  its  Uniformity,  i.  470.  Caft, 
Method  of  welding  with  Iron,  i.  575. 
Natural,  ii.  64.  German,  ii,  64,  Ma- 
nufaiture  of,  ii.  64,  Caft,  Manufafture 
of,  ii,  102,  Properties  and  Ufes  of  va- 
rious Kinds  of,  ii.  103.  Method  of  try- 
ing, ii.  104.     Of  Damafcus,  i  .  104. 

Stewart,  Sir  James,  ii.  284.     Dr.  ii,  427 

Stock  and  Dies,  for  making  very  perfeft 
Screws,  i.  163 

Stodart,  Mr.  on  the  Temper  of  Steel,  ii.  38.2 

Storch,  H.  on  the  Ruffian  Empire,  ii.  47 

Strabo,  i.  107.  ii.  t6,  21,  238 

Strachan,  Mr.  i.  148 

Strap,  on  a  Wheel,  fingular  Effeft  of,  i.  23 

Stream,  Method  of  meafuring  its  Force,  iii 
462 

Strings,  Elaftic  and  Mufical,  i.  328 

Strontian,  Obfervations  on,  by  Pelletier,  i. 
518.    Comparifon  of,  with  Barytes,  i.  510 

Sturmius,  ii.  345 

Styrian  Steel,  i.  328,  535 

Sugir,  Experiments  and  Obfervations  on 
the  Nature  of,  by  Cruicklhank,  i.  337. 
Hiftory  of,  ii.  136.  Maple,  ii.  304.  Ana- 
lyfis of,  by  Cruickfliank,  ii.  406 

Sulphates  of  Iron,  OxiJed  in  various  De- 
grees, i.  453.  Of  Soda,  ftparated  from 
Salt-water,  ii.  91. 

Sulphites,  i.  316,  364 

Sulphureous  Acid,  Properties  and  Habitude! 
of,  i.  143,  313.  Combinations  of,  i.  364. 
Rfll£f  of  on  Vegetable' Mntter,  i.  3S'5. 
Examination  of  the  Purity  of,  ii.  118 

Sulzer,  i.  519 

Suriurbrand,  ii.  20; 

Survey 


I 


N 


D        E 


X. 


563 


Survey,  trigonometrical,   of   England  and 

Wales,  ii.  550 
Sufpenfion  of  the  Mariner's  Compafs,  i.  426 
Swan,  Major,  C.  ii.  315 
Switzerland,  Geography  of,  i.  47 
Sydney  Earth,  Doubts  concerning  its  Exift- 

ence,  i.  404.     Analyfis  of,  ii.  7* 
Sylvius  Eneas,  i.  75 

T. 

Table  of  the  Degrees  of  Baum^'s  Hydro- 
meter, i.  39.  Of  Expanfions  of  Metals, 
by  Heat,  i.  58.  Of  Specific  Gravities  of 
Ardent  Spirit,  i.  117-  Of  Specific  Gra- 
vities of  Alloys  of  Tin  and  Lead,  118. 
Of  the  new  French  Meafurrs,  i.  198,  332. 
Of  Experiments  of  the  Force  of  Gun- 
powder, i.  468.  Of  the  Power  of  Salts 
for  producing  Cold,  i.  ;oi.  Of  French 
and  Englifli  Meafures,  ii.  J 84.  Of  the 
Prices  of  the  Ncceflaries  of  Life,  &c.  for 
700  Years,  ii.  284 

Tachenius,  i.  363 

Talc,  its  Elcftric  Capacity,  i.  358 

Tamerlane,  ii.  319 

Tanning,  by  Defmond's  Paitent,  i.  26.  The 
Improved  Procefs  of,  by  Seguin,- i.  271. 
Prouft  on  the  Principles  of,  ii.  337 

Tapping  of  Screws,  Enumeration  of  Errors 
in  this  Procefs,  i.  161 

Tar  from  Coal,  i.  494.  Mountain,  or  Mi- 
neral, ii.  203 

T?rtar,  Alkali  of.  Impropriety  of  its  various 
Denomiiiatienf,  i.  597 

Tartareous  Acid,  Method  of  detcfting  the 
Adulteration  of,  ii.  121 

Taflaert,  C.  i.  77 

Taffie,  Mr.  ii.  62 
'  Taylor,  Mr.  his  Mill-wheels,  i.  329 

Telegraph,  Mr.  Edgeworth's,  ii.  320.  Dr. 
Hooke's,  ii.  319 

Telefcdpes,  Achromatic,  i.  i.  Telefcopes 
improved  by  an  Iris,  or  variable  Aper- 
ture, i.  I  So 

Tellurium,  anew  Metal,  ii.  372 

Temperature,  Effc&s  of  the  Change  of,  on 
Metallic  Bodies,  i.  62.  Of  the  Globe, 
Eifefts  of  Water  in  equalizing,  i.  567. 
Efftfts  of  the  Change  of  on  compound 
metallic  B.irs,  i.  576.  Table  of,  near  the 
North-wetttrn  Lakes  of  America,  ii.  318 

Tempering  of  Steel,  new  Mode  of,  i.  38  i 

Tenacity  and  Hardnefs  in  Steel  are  diftinft 
Qualities,  i.  381 

Tennant  Smithfon,  efq.  F.R.S.  on  the  Na- 
ture of  the  Diamond,  i.  177,  199.  On 
the  Aftion  of  Nitre  on  Gold,  and  Pla- 
tina,  i.  30 

Tenon,  i.  46 

Terra  Auftralis,  or  Sydnea,  Analyfis  of, 
ii.  72 

Tertullian,  i.138 

Teftaceo,  Mount  its  cold  Caves,  229 

Tcffier,  Cit.  on  the  Sugar-maple,  ii.  304 

Tetens  on  Polynomials,  i.  47 

Teyler,  i.  242 

Thames,  Tunnel  beneath,  ii.  239,  473 

Theo,  ii.  185 

Theophraftus,  ii.  136 

Theories  of  the  cold  Winds,  iffuing  from 
the  Earth,  i.  233,  235 

Thefeusj  ii.  3 19 


Thomfop,  Sir  Benj.  his  Donation  for  a  Prize, 

i.  188,  225.  ii.  254 

Thouvenel,  Mr.  i.  170 

Thunder  Cloud,  Experiments  with  aa  ar- 
tificial, i.  436. 

Thunder  Storm,  Change  of  Colours,  and 
Direftion  of  Clouds,  during  a,  i.  265 

Tillet,  Matthew,  i.  140.  On  the  Alloy  of 
Gold  with  Tin,  ii.  140,  179 

Tilloch,  Mr.  ii.  476 

Timber  Trees,  advantageous,  ii.  333 

Time-pieces,  Methods  of  Correfition  for 
Temperature,  i.  55 

Tin,  Obfervations  on  the  Acid  of,  by  Guy- 
ton,  i.  543.  Effeft  of  a  Mixture  of  Gold 
with,  ii.  140,  179.  Prouft  on  its  Oxyda- 
tion,  ii.  515 

Tints,  Determination  of,  i.  93 

Toaldo,  Profeflbr,  i.  581 

Tompfon  on  the  Thermal  Baths  of  Italy, 
i.  239 

Toole,  Charles,  ii.  224 

Torpedo,  Experiments  toafccrta.in  the  The- 
ory of  its  bhock,  i.  355 

Tournfol,  Blae,  Procels  for  making,  ii.  311 

Townfon,  Dr.  i.  95.  Philcfophy  of  Mine- 
ralogy, ii.  378 

Tracy,  i.  46 

Tragacanth,  Gum,  ii.  409 

Tranfaftions,  Philofophical,  i.  191,479.11. 
142,  425 

Tranfmiflion  of  Sounds,  Experiments  on 
the,  i.  41! 

Travels  in  Germany  and  Switzerland,  i.  47. 
Mr.  Park's  in  Africa,  ii.  253,285,  329,  379 

Trcmbley,  i.  97 

Trees,  Account  of  three  diferent  Kinds  of 
advantageous  Timber,  ii.  333 

Trevor,  Mr.  ii.  95 

Trigonometrical  Survey  of  England  and 
Wales,  ii.  550 

Trigonometricus,  i.  238 

Troil,  Archbifliop  Von,  ii.  207 

Trommfdorff,  Profeffor,  his  Produftion  of 
Rock-cryftal  in  the  humid  Way,  i.  217. 
ii.  71  .,     ' 

Trooftvvyck.M.  Pacts  Van,  ii.  29 

Troughton,  Mr.  i.  59.  ii.  96,  314 

Trudaine,  Mr.  i.  32 

Tuckert,  Mr.  his  Defcription  of  the  Dutch 
Procefs  for  making  Cinnabar,  ii.  2 

Tunnel  beneath  the  Thames,  ii.  239,  473 

Turkey  Oak,  ii.  335 

Tufcany,  Grand  Duke  of,  ii.  265 

Tyrenfis  Willermiis,  i.  I39 

Tzetzes,  ii.  16,  20 

U. 

Undulation  of  Eleftricity,  i.  84 

Unifon,  Caufes  of  its  Differences  in  different 

Inftrurr.ents,  ii.  188 
Univerfal  Charafter,  by  Dr.  Anderfon,  ii. 

189.     By  Dr.  Brown,  ii.  190 
Urine   of  Animals,  Phofphoric    Acid   not 

contained  in  the,  ii.  71 
Uvedale,  John,  B.A.    on  the  Founder  of 

Huln  Abbey,  Northumbeiland,  ii.  188 
Uxbridge,  Lord,  ii.  367 

V. 
Vacuo,  Combuftion of  Phofphorus  in,  i.  279 
Vaili,  i.  363 


Valliere,  ii.  89 

Vandelli,  Profeffor,  on  Foffil  Pruffian  Blue 
and  native  Copper,  ii.  508 

Vander  Monde,  i.  210.  ii.  64 

Van  Marum,  Dr.  Martinus,  his  New  and 
Powerful  Eleftrlcai  Machine,  i.  83.  ii.  245, 
528.  On  Combuftion  of  Phofphorus,  i. 
279 

Van  Mons,  i.  44,  46,  144,  i65,  16S, 
359.  idj,  444.  ii.  374.  On  Detona- 
tions, ii.  469 

Van  Trooftwyk,  i.  44,  240,  241,  242 

Varley,  Mr.  his  perpetual  Motion,  i.  334, 

375 

Varto,  ii.  136 

Vauquelin,  i.  46,  53,  143,  168,  177,  204, 
210,  228,  248,  313.318,  361,364,385, 
444,  535.  ii.  6,  71,  105.  On  Siberian 
Red  Lead,  ii.  145,  156,213.  His  Ana- 
lyfis of  the  Beryl,  and  Difcovery  of  a  new 
Earth,  ii.  358.  His  Analyfis  of  the  Si- 
berian Red  Lead,  with  Experiments  911 
the  new  Metal  (Chrome)  which  it  eon- 
tains,  ii.  387.  Analyfis  of  the  ChryfoKte, 
ii.  414.  On  the  Siberian  Red  Lead,  ii. 
441 

Vega  Garcillaffo  Tie  La,,  i.  74 

Vegetable,  foluble  Principles  of  Aftringent,. 
i.  274 

Vegetable  Colours,  or  Lakes  of,  ii.  155. 
Matter,  Devclopement  of  Carbon  in,  ii. 
208 

Velho  Gonfalvo,  i.  74 

Venturi,J.  B.  i.  203,  205,  206,209.  ^'^ 
the  Principle  of  the  lateral  Communication 
of  Motion  in  Fluids,  &c.  i.  524,  Effay 
on  the  Works  of  Leonardo  Da  Vinci,  i. 
599.  On  the  lateral  Communication  of 
Motion  in  Fluids,  ii.  172,  On  the  lateral 
Motion  of  Fluids,  i.  273,  422,  487.  ii.  51, 
84,  89,  93 

Veruiam,  Bacon,  on  Univerfal  Language,  ii, 

343-. 

Vclpucius,  i.  73,  no 

Vcffels,  wide-mouthed,.  Method  of  clofing 
to  render  them  Air-tight,  i.  260 

Vieweg  Ftid,  i.  47 

Viilars,  Cit.  ii.  23>6 

Villtterque,  Cit.  ii.  138 

Vince,  Rev.  S.  A.M.  F.R.S.  on  the  Lever, 
i.  541 .  On  the  Reliftance  of  Bodies  mov- 
ing in  Fluids,  ii.  142 

Vinci,  ii.  83. 

Vinegar,  diftiiled.  Method  of  dete61ing  the 
Adulteration  of,  ii.  120 

Virgil,  ii.  13 

Vifion,  Relearches  on  the  Procefs  by  which 
it  is  rendered  diftinft,  i.  305,  472,  549. 
Le  da  Vinci  on,  ii.  89 

Vitality,  Chemical  Procefs  of,  i.  359 

Vitriol,  Oil  of,  Examination  of  the  Pucity 
of,  ii.  1 18 

Vitriaco  Jacobus  de,  ii.  139 

Vitruvlus,  li.  50 

Voices,  Variety  of,  ii.  188 

Volatile  Oils,  how  affeded  by  Cold,  i.  i2i, 
227 

Volcanic  Prod uflions,  i.  285 

Votta,  i.   203,  256,  257,  335,  396,  397,  39S 

Von  Aken,  M.  i.  279 

Vulliamy,  Mr.  Benjamin,  his-  artificial  over- 
flowing Well,  ii.  276 

Wadftrom, 


5^4 


N       D 


X. 


w. 

Wadftrom,  Dr.  ii.  456,  15J 

Wagenfeil,  Dr.  i.  75 

Wainlcot  Oak,  11.335 

Walckier's,  his  Silk  Machine  for  Eleflricity, 

ii.  4JO 
Wales,  North,  Geological  Obfervations  on, 

i.  tto 
Walker,  Mr.  Richard,  on  Artificial  Cold,  i. 

497 

. Steel,  i.  576 

Wallace,  William,  Geometrical  Porifms,  ii. 

i9i 

Wallerius,  i.  14.  ii.  204 

Wallingfort,  his  ancient  Watch,  ii.  51 

Ward,  li.  84. 

Wargentin,  ii.  116,  izS 

Warrens,  i.  359 

Watches,  Obfervations  on  the  Efcapements 
of,  i.  419.  On  the  maintaining  Power 
of,  ii.  49.     Efcapements  for,  ii.  50 

Water,  Dccompofition  of  by  tleftrie  Dif- 
charges,  i.  141,  349.  Etfefts  of  in  equa- 
lising the  Temperature  nf  the  Globe,  i. 

■  567.  Spouts,  account  of  the  Appearance 
of,  by  M.  Michaud,  i.  577.  Circular 
Eddies  or  Whirls  of,  ii.  8li.  General 
Fafls  relative  to  its  Mo'ion  by  L.  dc 
Vinci,  ii.  88.  Upwards  of  Two  Gall  >ns 
made  to  boil  by  Friftion,  ii.  113.  Conge- 
lation o.f,  ii.  163.  Diftilled  for  Chemical 
Experiments,  economical  Mode  of  obtain- 
ing, ii.  209.  Water,  eafy  Mode  of  pu- 
rifying, by  Barytes,  ii.  113.  Expence 
of  as  a  firft  Mover,  ii.  459.  Mills,  Power 
of,  ii.  464.  Wheels,  Bucket  and  Breaft, 
compared,  ii.  497,  544 

Watfon,  Dr.  i.  192,  494,  496,  575.    Major, 

ii.   95.     Mr.  White,  li.  249 
Watt,  Mr.  i.  424.  ii.  46 
Watte,  John,  ii.  96 


Weather  Inftrument,  Laiowflti's  New,  ii.  1 1 

Weaver,  Mr.  ii.  l^^ 

Wedgwood,  Thomas,  i.  363 

■  I  Mr.  on  Sydney  Earth,  L  404. 

ii.  TS 
Weights,  Table  of  the  new  French,  i.  199. 

Table  of   French  and  Comparifon  with 

Englilh,  i.   331. 
Welding  of  Caft-fteel  with  Iron,  i.  575 
Welte,  i.  143 
Welter,  Cit.  i.  329 
Well,  artificial,  overflowing  of,  by  VuHiamy, 

ii.  176 
Welther,  Cit.  his  Procefs  for  making  Car- 
bonate '.f  Potafli,  ii.  369 
Wenzel,  i.  100.  ii.  340 
Werner,  i.  537 
Weftrumb,  Mr.i.  144 
Wheat,  Prices  of,  at  different  Periods,  ii.  284 
Wheels  without  Co,;s,  i.  329.     Underfliot 

and  Overfhot  compared,  li.  464 
Whiiftone,  Caufes  of  the  ftony  Charafter 

of,  ii.  285 
White,  Charles,  Efq.  F.R.S.     Account  of 

three  valuable  Timber  Trees,  ii.  190,  333 
Whitehurft,  Mr.  John,    F.R.S.  i.  57,  65. 

ii.  95 
Whitworth,  ii.  95 
Wick  of  Candles  and  Lamps,  i.  68 
Wicks,  economical,  i.  69 
Widmanftal,  ii.  84 
Widenmann,  ii.  204,  248 
Wilcke,  i.  396 
Wilkins,  Bi'hop,  his  perpetu?!  Motion,  i. 

376.  ii.  191.     Account  of  his  Philofophi- 

cal  Language,  ii.  346 
Wilkinfon,  General,  ii.  315 
Williams,  Lieut.  Col.  i.  150,  198 
Willis,  i.  363 
:  Wilfon,  Profeffor,  on  Multiplying  engraved 
Plates,  ii.  60 


Wilfon,  Patrick,  F.R.S.  on  a  felf-moving 

Lamp,  ii.  167,  192 
Winds,  Coid,   iffuiog  out  of  the  Earth,  i, 

i»9.  233 
Wind  as  a  lift  Mover,  ii.  459,  461     Weft. 

erly  in  LtUnd,  have  of  kte  Years  blowa 

with  uncommon  Violence,  ii.  382 
Wire-cl  jrh  ror  Lantho  ns,  ii.  412.     Fufed 

by  Eleftacity,  ii.  526.     Ufed  as  a  Wa- 

ther  Inftrument,  ii.  1 1 
Wittman,  Dr.  i.  286 
Wood,  Bituminous,  ii.  206.     Engraving  on, 

Woodward,  Dr.  ii.  477 

Wool,  Soap  of,  i.  40 

Worceftcr,  Marquis  of,  i.  376.  Scheme  for 
Perpetual  Motion,  i.  377.  DeTcription  of 
his  Steiitii  Enj;ine,  i.  419.  ii.  228 

World,  Syftem  of  the,  by  Laplace,  ii.  39 

Worfley,  Sir  Richard,  ii.  95 

Woulfe,  Mr.  ii.  14J,  319 

Wounds,  Effeft  of  Galvanic  Irritation  on,  i. 
Z56 


Xerxes,  ii.  319 

Y. 

Yeaft,  fubllitute  for  in  making  Bread,  i.  167- 

ii-  357 
Yelin,  ii.  8 

Yellow,  Procefs  for  dying  Silk,  i.  gz 
Yeoman,  Mr.  ii.   95 
York,  Duke  of,  i.  328 
Young,  Mr.  Thomas,  on  Vi lion,  i.  305 
—  Sir  William,  i.  190 

Z. 

Zebra,  curious  Fafts  refpefting  'he  Propa* 

gation  of,  ii.  267 
Zoonic  Acid,  ii.  367 


ERRATA  IN  VOL.  II. 


Page.  Line. 

29     .3  from  the  bottom,  fdtas,  read  aa 
46     13  il'ter  /--^?  424,  infcrt  fol.  L 

The  pidit:  of  Apparams  feould  be 
numbered  II. 
14'S     18  ioT  periodical,  read  fynodic 

19  for  t  d.  8  h.  26  J*,  m.  read  i  d.  18  h. 
28  m.  36  s. 
t;4     37  for  Hot  qutie-^n'',  r^^d  upwards  of 

-30" 
—I    40  for  97I  lijy'i  »/<•,  read  iiTand^-j\ 

day's  ufe  reJpeRi'vely 
—     vlt.,  for  X  read  of- 
125     11  What  is  faid  of  tie  firfl  and  fecond 
Jateiliies,  refps/fting  the  annual 


Page.  Line. 

error,  is  exaftly  true,  only  with 
refpeft  to  I  he  fecond  :-~x\\e  error 
of  the  firfi  being  minus,  and  in  a 
(mailer  proportion. 

264  —  In  fome  copies,  the  figures  in  the 
Mote  have  flipped,  and  give  an 
imperfeft  imprelfion.  Read /Af 
amount  of  Gold  coined  between  ibe 
years  1762  and  1772  both inclu- 
Ji've,  -was  8,157,203/.  1 5J.  dd. 
and  bet-ween  1782  nndljgz,  both 
inclufive,  -was  19,675,666/.  14). 
kd.  andbetween  1773  and  1777, 
both  inclufive,  was  «9?59',833/. 


Page.  Line. 

IS.  And  in  the  fourth  line  from 
the  bottom,  read  reckoned  at  J 
(i}alfj  per  cent. 

275       8  read  the  pipe  A  B  F  E 

439       8  from  the  bottom  for_/?«/ir  read /i/flW 

488  14  from  the  bottom,  erafe  the  full  ftop 
after  the  word  polijbed,  and  add 
a  ftill  ttop  after  Unpi)  , 

490  *j  for  offered,  re.id  afforded 

—  3  from  the  (■■  ottom  for  K  B  read  K  D 

491  12  read  interi  r  part  of  the  tube 

—  3  from  the  i.Jttora  for  D  D  F  C  read 

DB70 
5 58      6  ioT  £iringucci»}  tQid  Beriitguccius,