﻿480 
  Transactions. 
  — 
  Chemistry. 
  

  

  one 
  cannot 
  obtain 
  a 
  homogeneous 
  sphere 
  of 
  it 
  for 
  use, 
  or 
  if 
  one 
  could 
  it 
  

   would 
  at 
  once 
  lose 
  its 
  character 
  and 
  shape. 
  The 
  oil 
  then 
  being 
  of 
  necessity 
  

   produced 
  irregularly 
  around 
  the 
  camphor 
  spreads 
  unequally 
  from 
  it, 
  and 
  in 
  

   the 
  act 
  urges 
  it 
  in 
  a 
  direction 
  which 
  is 
  away 
  from 
  that 
  side 
  on 
  which 
  there 
  

   is 
  the 
  greatest 
  output 
  of 
  oil 
  ; 
  thus 
  the 
  camphor 
  breaks 
  through 
  the 
  oily 
  

   film 
  at 
  its 
  weakest 
  part, 
  and 
  sets 
  itself 
  upon 
  the 
  edge 
  thereof, 
  which 
  posi- 
  

   tion 
  it 
  retains 
  so 
  long 
  as 
  there 
  is 
  motion 
  produced. 
  The 
  movements 
  of 
  cam- 
  

   phor 
  are, 
  in 
  short, 
  the 
  joint 
  results 
  of 
  the 
  outward 
  spread 
  of 
  oil 
  along 
  the 
  

   water 
  surface— 
  the 
  inertia 
  or 
  adhesiveness 
  of 
  this 
  oil 
  as 
  regards 
  what 
  

   surface 
  it 
  thus 
  occupies 
  — 
  and, 
  lastly, 
  the 
  antipathy, 
  as 
  it 
  were, 
  which 
  exists 
  

   between 
  the 
  two, 
  the 
  camphor 
  and 
  its 
  oil, 
  whereby 
  they 
  refuse 
  to 
  associate. 
  

  

  But 
  the 
  questions 
  will 
  now 
  without 
  doubt 
  present 
  themselves 
  to 
  you 
  — 
  • 
  

   Why 
  should 
  the 
  oil 
  spread 
  so 
  determinately 
  over 
  the 
  water 
  and 
  retain 
  the 
  

   position 
  thus 
  gained 
  so 
  obstinately 
  ? 
  and 
  why 
  should 
  it 
  appear 
  to 
  repel 
  

   camphor 
  ? 
  Unto 
  such 
  questions 
  I 
  might 
  with 
  propriety 
  reply, 
  that 
  to 
  

   entertain 
  them 
  here 
  is 
  not 
  incumbent 
  upon 
  me, 
  as 
  I 
  have 
  now 
  completed 
  

   the 
  task 
  I 
  set 
  myself 
  in 
  this 
  paper, 
  by 
  showing 
  that 
  camphor 
  moves, 
  as 
  we 
  

   have 
  seen, 
  upon 
  water, 
  for 
  the 
  same 
  reason 
  that 
  solid 
  particles 
  occupying 
  a 
  

   water-surface 
  move 
  when 
  oil 
  is 
  added. 
  To 
  treat 
  such 
  questions 
  is 
  really 
  to 
  

   take 
  up 
  another 
  subject, 
  and 
  one 
  which 
  includes 
  within 
  its 
  scope 
  the 
  

   behaviour 
  of 
  oils 
  generally 
  with 
  water 
  when 
  in 
  presence 
  of 
  it 
  — 
  a 
  subject, 
  

   moreover, 
  which 
  I 
  had 
  reserved 
  for 
  a 
  further 
  communication 
  to 
  you 
  ; 
  but 
  

   rather 
  than 
  leave 
  the 
  matter 
  in 
  hand 
  in 
  a 
  state 
  which 
  may 
  to 
  some 
  appear 
  

   unfinished, 
  I 
  will 
  trench 
  upon 
  these 
  subjects 
  so 
  far 
  as 
  to 
  make 
  a 
  few 
  general 
  

   observations 
  thereupon 
  in 
  elucidation 
  of 
  these 
  questions. 
  It 
  is, 
  however, 
  

   proper 
  that 
  I 
  should 
  premise 
  these 
  observations 
  with 
  a 
  short 
  statement 
  of 
  

   the 
  prevailing 
  opinion 
  as 
  to 
  the 
  reason 
  of 
  the 
  extensive 
  spread 
  of 
  even 
  

   minute 
  quantities 
  of 
  oil 
  upon 
  water 
  under 
  favourable 
  circumstances, 
  and 
  

   their 
  refusal 
  to 
  mix 
  under 
  other 
  circumstances. 
  

  

  According 
  to 
  these 
  opinions, 
  and 
  these 
  are 
  both 
  the 
  popular 
  and 
  scien» 
  

   tific 
  ones, 
  the 
  spread 
  of 
  oil 
  upon 
  water 
  is 
  simply 
  the 
  result 
  of 
  gravitation 
  in 
  

   conflict 
  with 
  the 
  cohesiveness 
  of 
  the 
  oil, 
  and 
  the 
  apparent 
  antipathy 
  which 
  

   they 
  manifest 
  towards 
  each 
  other, 
  is 
  the 
  result 
  of 
  an 
  exertion 
  of 
  a 
  repul- 
  

   sive 
  property 
  innate 
  in 
  one 
  or 
  the 
  other, 
  or 
  in 
  both. 
  Thus 
  it 
  seems 
  to 
  me 
  

   that 
  the 
  possibility 
  of 
  chemical 
  reactions 
  being 
  concerned 
  in 
  each 
  of 
  these 
  

   operations 
  has 
  not 
  been 
  contemplated, 
  and 
  so, 
  as 
  I 
  am 
  persuaded, 
  an 
  

   important 
  factor 
  in 
  both 
  these 
  problems 
  has 
  been 
  left 
  out 
  of 
  consideration. 
  

   In 
  opposition, 
  then, 
  to 
  such 
  opinions, 
  I 
  will 
  maintain 
  here 
  that 
  both 
  the 
  

   spread 
  of 
  oil 
  upon 
  water 
  in 
  thin 
  films, 
  and 
  the 
  apparent 
  repulsion 
  which 
  

   may 
  be 
  seen 
  to 
  occur 
  between 
  the 
  two, 
  are 
  brought 
  about 
  mainly 
  through 
  

   the 
  satisfaction 
  of 
  chemical 
  affinity. 
  

  

  