﻿Skey. 
  — 
  On 
  the 
  Movements 
  of 
  Camphor 
  on 
  Water, 
  47S 
  

  

  are 
  equal, 
  eacli 
  of 
  the 
  substances 
  whose 
  vapours 
  we 
  are 
  operatmg 
  with, 
  is 
  

   at 
  such 
  times 
  subjected 
  on 
  all 
  sides 
  to 
  a 
  force 
  tending 
  to 
  diive 
  it 
  in, 
  that 
  is, 
  

   towards 
  its 
  centre 
  ; 
  a 
  force 
  which, 
  as 
  it 
  cannot 
  be 
  persistently 
  equal 
  around 
  

   it, 
  will 
  certainly 
  move 
  it 
  from 
  its 
  normal 
  position. 
  

  

  This 
  is, 
  I 
  allow, 
  a 
  conclusion 
  which 
  one 
  is 
  at 
  first 
  inclined 
  to 
  form 
  ; 
  but 
  

   I 
  will 
  now 
  show 
  to 
  you 
  an 
  extension 
  of 
  this 
  experiment 
  yielding 
  results 
  

   which 
  will, 
  I 
  think, 
  at 
  once 
  prevent 
  anyone 
  previously 
  so 
  inclined 
  from 
  this 
  

   conclusion. 
  

  

  The 
  camphor 
  is 
  now 
  only 
  one-sixth 
  of 
  an 
  inch 
  above 
  the 
  water, 
  and 
  the 
  

   diameter 
  of 
  the 
  cleared 
  space 
  below 
  it 
  is 
  about 
  half 
  an 
  inch 
  ; 
  I 
  now 
  lower 
  

   it 
  to 
  within 
  one-fortieth 
  of 
  an 
  inch 
  of 
  the 
  water, 
  but 
  you 
  observe 
  that 
  the 
  

   area 
  of 
  cleared 
  space 
  is 
  not 
  perceptibly 
  increased, 
  thereby 
  showing 
  that 
  

   this 
  is 
  very 
  closely 
  upon 
  the 
  maximum 
  of 
  that 
  which 
  can 
  be 
  got 
  by 
  placing 
  

   the 
  camphor 
  at 
  an 
  infinitesimal 
  distance 
  from 
  the 
  water. 
  I 
  now 
  allow 
  it 
  

   the 
  slightest 
  contact 
  with 
  the 
  water 
  which 
  I 
  possibly 
  can, 
  and 
  you 
  observe 
  

   that 
  there 
  is 
  instantly 
  a 
  very 
  large 
  increase 
  of 
  cleared 
  space, 
  whose 
  

   diameter 
  is 
  certainly 
  not 
  less 
  than 
  four 
  inches, 
  representing, 
  therefore, 
  an 
  

   area 
  no 
  less 
  than 
  sixty-four 
  times 
  that 
  which 
  we 
  had 
  before. 
  

  

  Here, 
  then 
  we 
  have, 
  in 
  one 
  moment, 
  an 
  accession 
  to 
  our 
  knowledge 
  of 
  a 
  

   kind 
  which 
  teaches 
  us 
  that, 
  whatever 
  the 
  direct 
  radiation 
  of 
  camphor 
  vapour 
  

   may 
  have 
  to 
  do 
  with 
  the 
  production 
  of 
  the 
  cleared 
  space 
  last 
  got, 
  there 
  is 
  

   some 
  reaction 
  of 
  camphor 
  with 
  water 
  of 
  quite 
  a 
  different 
  nature 
  which 
  has 
  

   very 
  much 
  more 
  to 
  do 
  with 
  it 
  ; 
  so 
  great, 
  indeed, 
  is 
  the 
  effect 
  produced 
  by 
  

   the 
  merest 
  contact 
  as 
  compared 
  with 
  that 
  obtained 
  by 
  suspension 
  in 
  the 
  most 
  

   favourable 
  position, 
  that 
  it 
  really 
  becomes 
  a 
  moot 
  point 
  whether 
  any 
  space 
  

   at 
  all 
  is 
  cleared 
  by 
  the 
  direct 
  impingement 
  of 
  this 
  vapour 
  on 
  the 
  water 
  

   surface. 
  

  

  To 
  settle 
  this 
  point 
  by 
  a 
  demonstration 
  I 
  now 
  reproduce 
  certain 
  experi- 
  

   ments 
  of 
  mine 
  : 
  — 
  This 
  small 
  sphere 
  of 
  camphor 
  I 
  suspend 
  over 
  water 
  (pre- 
  

   pared 
  as 
  above) 
  within 
  one-sixth 
  of 
  an 
  inch 
  of 
  its 
  surface, 
  and 
  across 
  

   the 
  cleared 
  space 
  produced, 
  close 
  to 
  the 
  camphor 
  and 
  closer 
  to 
  the 
  water 
  

   than 
  the 
  camphor 
  is, 
  I 
  place 
  this 
  thin 
  bar; 
  now 
  this 
  clearing 
  should 
  have 
  

   its 
  shape 
  materially 
  altered, 
  and 
  its 
  area 
  much 
  curtailed 
  if 
  it 
  has 
  been 
  

   produced 
  by 
  the 
  mere 
  impingement 
  of 
  vapour 
  on 
  water; 
  but 
  you 
  cannot 
  see 
  

   that 
  any 
  variation 
  occm's 
  whether 
  in 
  shape 
  or 
  area. 
  

  

  Again, 
  I 
  place 
  a 
  small 
  piece 
  of 
  camphor 
  on 
  this 
  prepared 
  surface, 
  

   and 
  put 
  a 
  wide 
  bar 
  close 
  to 
  one 
  side 
  of 
  it 
  and 
  very 
  near 
  to 
  the 
  water 
  ; 
  

   now, 
  action 
  and 
  reaction 
  being 
  equal 
  there 
  should 
  occur 
  a 
  marked 
  

   recession 
  of 
  the 
  camphor 
  from 
  the 
  bar 
  if 
  the 
  evaporation 
  theory 
  is 
  correct, 
  

   for 
  in 
  the 
  direction 
  of 
  this 
  bar 
  is 
  the 
  greatest 
  resistance 
  to 
  the 
  escaping 
  

   vapour 
  ; 
  but 
  you 
  cannot 
  observe 
  that 
  anything 
  of 
  this 
  kind 
  happens. 
  

  

  