﻿490 
  Transactions. 
  — 
  Cliemistry. 
  

  

  numerous 
  cases 
  wliicli 
  are 
  analogous 
  to 
  the 
  present 
  one, 
  that 
  I 
  need 
  not 
  do 
  

   more 
  than 
  point 
  out 
  to 
  you 
  the 
  fact 
  that 
  such 
  a 
  kind 
  of 
  application 
  would 
  

   then 
  be 
  both 
  right 
  and 
  necessary 
  to 
  make. 
  

  

  Art. 
  LXXXIII. 
  — 
  On 
  the 
  Nature 
  and 
  Cause 
  of 
  Tomlinson'' 
  s 
  Cohesion 
  Figures. 
  

  

  By 
  William 
  Skey. 
  

   [Read 
  before 
  the 
  Wellington 
  Philosophical 
  Society, 
  9th 
  Noveviber, 
  1878.] 
  

   It 
  has 
  long 
  since 
  been 
  known 
  that 
  when 
  any 
  oil 
  is 
  suffered 
  to 
  flow 
  on 
  water 
  

   in 
  very 
  thin 
  films 
  a 
  beautiful 
  play 
  of 
  colours 
  is 
  produced 
  ; 
  but 
  it 
  was 
  not 
  

   till 
  the 
  year 
  1868 
  that 
  it 
  was 
  observed 
  certain 
  figures 
  were 
  at 
  the 
  same 
  time 
  

   formed 
  at 
  a 
  rate 
  and 
  of 
  a 
  pattern 
  varying 
  according 
  to 
  the 
  kind 
  of 
  oil 
  used. 
  

  

  These 
  figures 
  are 
  made 
  up 
  of 
  small 
  annular 
  spaces, 
  set 
  in 
  a 
  ground 
  of 
  a 
  

   different 
  shade, 
  and 
  are 
  known 
  as 
  Tomlinson's 
  cohesion 
  figures, 
  after 
  Prof. 
  

   Tomlinson, 
  the 
  discoverer 
  of 
  them. 
  They 
  are 
  employed 
  by 
  Dr. 
  Moffat, 
  

   lecturer 
  on 
  chemistry, 
  at 
  Glasgow, 
  to 
  base 
  thereon 
  a 
  system 
  of 
  olegraphy 
  

   (that 
  is, 
  one 
  by 
  which 
  oil 
  may 
  be 
  identified), 
  and 
  it 
  is 
  their 
  precise 
  nature 
  

   and 
  more 
  immediate 
  cause 
  which 
  I 
  now 
  wish 
  to 
  discuss 
  before 
  you, 
  as 
  I 
  

   have 
  been 
  led 
  by 
  recent 
  investigations 
  of 
  mine 
  upon 
  oils, 
  to 
  believe 
  that 
  

   neither 
  the 
  one 
  nor 
  the 
  other 
  have 
  been 
  heretofore 
  in 
  the 
  least 
  apprehended, 
  

   and 
  this, 
  because 
  the 
  possibility 
  of 
  chemical 
  reactions 
  being 
  involved 
  in 
  the 
  

   production 
  of 
  these 
  figures 
  has 
  not 
  been 
  contemplated. 
  

  

  Thus, 
  as 
  far 
  as 
  I 
  can 
  gather 
  from 
  the 
  statements 
  of 
  Prof. 
  Tomlinson 
  

   and 
  Dr. 
  Moffat 
  (the 
  only 
  scientists 
  who 
  have, 
  within 
  my 
  knowledge, 
  inves- 
  

   tigated 
  this 
  subject), 
  the 
  annular 
  spaces 
  are 
  "perforations" 
  or 
  "holes," 
  

   bottoming, 
  as 
  it 
  necessarily 
  follows, 
  upon 
  the 
  water-surface 
  used, 
  and 
  set 
  in 
  

   a 
  ground 
  which 
  is 
  presumedly 
  formed 
  of 
  oil. 
  Now 
  I 
  think 
  the 
  annexed 
  

   account 
  of 
  observations 
  made 
  by 
  me, 
  will 
  show 
  to 
  you 
  very 
  clearly 
  that 
  all 
  

   this 
  is 
  directly 
  opposed 
  to 
  the 
  facts 
  of 
  the 
  case. 
  

  

  First, 
  then, 
  in 
  regard 
  to 
  the 
  annular 
  spaces 
  (the 
  so-termed 
  " 
  perfora- 
  

   tions" 
  or 
  "holes"). 
  A 
  careful 
  inspection 
  of 
  them 
  showed 
  me 
  that 
  the 
  

   surface 
  in 
  these 
  parts 
  is 
  not 
  at 
  all 
  depressed 
  as 
  compared 
  with 
  that 
  of 
  the 
  

   rest 
  of 
  the 
  patterns, 
  but 
  is, 
  on 
  the 
  contrary, 
  raised, 
  either 
  in 
  flat 
  or 
  round- 
  

   topped 
  hills 
  according 
  as 
  these 
  spaces 
  are 
  of 
  large 
  or 
  small 
  extent. 
  I 
  

   further 
  found 
  that 
  the 
  liquid 
  occupying 
  these 
  parts 
  — 
  that 
  is, 
  the 
  hills 
  — 
  

   burns 
  completely 
  away, 
  and 
  without 
  the 
  least 
  splattering, 
  showing 
  that 
  it 
  

   is 
  an 
  oiL 
  

  

  