﻿474 
  Transactions. 
  — 
  Chemistry. 
  

  

  and 
  the 
  more 
  so 
  •when, 
  on 
  enquiring 
  into 
  this, 
  he 
  learns 
  that 
  no 
  one 
  has 
  yet 
  

   pubHshed 
  anything 
  in 
  explanation 
  of 
  this 
  phenomenon 
  which 
  is 
  backed 
  

   either 
  with 
  any 
  kind 
  of 
  authority 
  or, 
  what 
  is 
  more, 
  by 
  a 
  weight 
  of 
  evidence 
  

   sufficient 
  to 
  recommend 
  it 
  for 
  his 
  unqualified 
  belief. 
  

  

  It 
  was 
  just 
  under 
  these 
  incentives 
  to 
  research 
  that, 
  a 
  little 
  while 
  ago, 
  I 
  

   commenced 
  investigating 
  this 
  phenomenon, 
  and 
  with 
  the 
  additional 
  one 
  of 
  

   ultimately 
  finding 
  something 
  in 
  common 
  between 
  it 
  and 
  that 
  of 
  the 
  motion 
  

   of 
  minute 
  particles 
  in 
  certain 
  liquids 
  — 
  one 
  known 
  by 
  the 
  appellation 
  of 
  

   " 
  Browinian 
  movements 
  " 
  — 
  the 
  Pedetic 
  movements 
  of 
  Prof. 
  Jevons. 
  

  

  After 
  I 
  had 
  made 
  a 
  great 
  number 
  of 
  experim^ts 
  with 
  camphor, 
  how- 
  

   ever, 
  I 
  could 
  find 
  nothing 
  which 
  gave 
  any 
  proof 
  in 
  favour 
  of 
  a 
  common 
  origin 
  

   for 
  the 
  two 
  phenomena. 
  Neither 
  could 
  I 
  find 
  anything 
  in 
  support 
  of 
  the 
  

   theory 
  popularly 
  assigned 
  for 
  the 
  explanation 
  of 
  that 
  exhibited 
  by 
  camphor, 
  

   but 
  instead, 
  evidence 
  of 
  a 
  very 
  decided 
  character, 
  pointing, 
  as 
  I 
  think, 
  

   very 
  clearly 
  to 
  quite 
  a 
  different 
  omgin 
  for 
  it 
  than 
  that 
  which 
  is 
  assigned 
  

   by 
  the 
  theory 
  in 
  question. 
  This 
  I 
  now 
  ask 
  leave 
  to 
  submit 
  to 
  your 
  

   inspection, 
  and, 
  if 
  you 
  will 
  aUow 
  me, 
  I 
  will 
  do 
  this 
  in 
  the 
  same 
  order, 
  or 
  

   nearly 
  so, 
  in 
  which 
  it 
  was 
  educed. 
  

  

  First, 
  I 
  will 
  remind 
  you 
  what 
  this 
  theory 
  is, 
  which 
  is 
  thus 
  endorsed 
  by 
  

   popular 
  opinion. 
  It 
  is 
  based 
  upon 
  the 
  fact 
  that 
  camphor 
  gives 
  off 
  vapour 
  

   at 
  common 
  temperatures, 
  and 
  it 
  is 
  to 
  the 
  unequal 
  impingement 
  of 
  this 
  

   vapour 
  upon 
  the 
  water 
  around 
  it 
  that 
  the 
  movements 
  in 
  question 
  are 
  

   ascribed, 
  the 
  camphor 
  being 
  held, 
  as 
  I 
  suppose, 
  to 
  move 
  in 
  the 
  direction 
  of 
  

   least 
  evaporation. 
  

  

  Now 
  this 
  does, 
  I 
  allow, 
  appear 
  at 
  first 
  thought 
  quite 
  explanatory 
  to 
  

   anyone 
  who 
  will 
  observe 
  the 
  effect 
  which 
  camphor 
  vapour, 
  or 
  vapours, 
  

   generally 
  have 
  upon 
  water, 
  the 
  surface 
  of 
  which 
  is 
  prepared 
  so 
  as 
  to 
  

   indicate 
  any 
  modification 
  it 
  thereby 
  undergoes. 
  Such 
  a 
  surface, 
  in 
  the 
  case 
  

   of 
  water, 
  is 
  easily 
  got 
  by 
  dredging 
  a 
  little 
  very 
  finely-powdered 
  resin 
  evenly 
  

   upon 
  it.* 
  

  

  Camphor 
  suspended 
  close 
  to 
  a 
  surface 
  of 
  this 
  kind 
  produces, 
  as 
  you 
  see, 
  

   an 
  instantaneous 
  recession 
  of 
  the 
  resinous 
  particles 
  from 
  the 
  point 
  imme- 
  

   diately 
  under 
  it; 
  the 
  same 
  effect 
  is 
  also 
  produced 
  by 
  those 
  substances 
  

   generally 
  which 
  give 
  off 
  vapour 
  in 
  suitable 
  quantity 
  at 
  the 
  temperature 
  at 
  

   which 
  they 
  are 
  used 
  ; 
  for 
  instance, 
  alcohol 
  or 
  ether. 
  

  

  It 
  does, 
  indeed, 
  appear 
  from 
  this, 
  that 
  the 
  popular 
  theory 
  which 
  we 
  are 
  

   attacking 
  is, 
  after 
  all, 
  correct. 
  One 
  sees 
  the 
  resin 
  quickly 
  dashed 
  away 
  from 
  

   the 
  camphor, 
  etc., 
  and 
  in 
  consequence 
  conclude 
  that, 
  as 
  action 
  and 
  reaction 
  

  

  * 
  This 
  surface 
  so 
  weU 
  indicates 
  (by 
  the 
  displacement 
  of 
  resin) 
  the 
  presence 
  of 
  oily 
  

   matters 
  that 
  these 
  can 
  readily 
  be 
  detected, 
  as 
  they 
  escape 
  from 
  the 
  finger 
  applied 
  thereto, 
  

   eyen 
  immediately 
  after 
  a 
  thorough 
  wash. 
  

  

  