﻿476 
  Transactions.^^Chemistru, 
  

  

  Evidence 
  of 
  tliis 
  sort, 
  indeed, 
  is 
  to 
  be 
  had 
  in 
  every 
  exliibition 
  of 
  these 
  

   movements 
  of 
  camphor, 
  for 
  whenever 
  the 
  camphor 
  gets 
  to 
  the 
  vessel's 
  

   side, 
  it 
  remains 
  there 
  motionless, 
  whereas 
  it 
  should 
  (according 
  to 
  the 
  theory 
  

   we 
  are 
  examining) 
  rebound 
  therefrom, 
  with 
  great 
  force. 
  

  

  But 
  apart 
  from 
  and 
  independent 
  of 
  these 
  results, 
  it 
  is, 
  as 
  I 
  conceive, 
  

   very 
  questionable 
  whether 
  any 
  vapour 
  emanating 
  from 
  a 
  substance 
  which 
  is 
  

   of 
  the 
  same 
  temperature 
  as 
  its 
  environment, 
  and 
  in 
  presence 
  of 
  air, 
  has 
  a 
  

   direct 
  repellent 
  effect 
  thereon. 
  However, 
  this 
  is 
  a 
  question 
  of 
  so 
  general 
  a 
  

   character 
  that 
  I 
  cannot 
  well 
  extend 
  the 
  scope 
  of 
  this 
  paper 
  so 
  far 
  as 
  to 
  

   take 
  it 
  into 
  consideration 
  now, 
  but 
  if 
  you 
  will 
  allow 
  me 
  I 
  will 
  trench 
  upon 
  

   it 
  so 
  much 
  as 
  to 
  inform 
  you 
  of 
  a 
  few 
  very 
  interesting 
  facts 
  which 
  are 
  con- 
  

   nected 
  with 
  it, 
  and 
  also 
  in 
  an 
  especial 
  manner 
  with 
  the 
  particular 
  phenomena 
  

   we 
  are 
  considering. 
  

  

  Experiments.' 
  — 
  Two 
  pieces 
  of 
  camphor 
  swung 
  in 
  air 
  in 
  close 
  contiguity, 
  

   at 
  the 
  ends 
  of 
  very 
  fine 
  and 
  long 
  threads, 
  do 
  not 
  manifest 
  any 
  repellent 
  effect 
  

   in 
  regard 
  to 
  each 
  other, 
  while, 
  if 
  placed 
  upon 
  water, 
  though 
  at 
  first 
  there 
  is 
  

   an 
  appearance 
  of 
  a 
  mutually 
  repellent 
  force 
  in 
  action, 
  there 
  is, 
  after 
  a 
  short 
  

   time 
  has 
  elapsed, 
  an 
  ajopearance 
  of 
  a 
  mutually 
  attractive 
  force 
  — 
  they 
  actually, 
  

   as 
  you 
  see, 
  move 
  toward 
  each 
  other 
  and 
  close 
  together. 
  Now, 
  you 
  wiU 
  allow 
  

   that 
  these 
  results 
  are 
  not 
  consistent 
  with 
  the 
  theory 
  which 
  credits 
  vapour 
  

   with 
  direct 
  repulsive 
  effects. 
  The 
  case 
  of 
  turpentine 
  is 
  something 
  similar 
  

   to 
  the 
  above. 
  It 
  is 
  a 
  substance 
  which 
  gives 
  off 
  vapour 
  more 
  freely 
  

   than 
  camphor, 
  yet 
  when 
  one 
  sprinkles 
  fine 
  particles 
  of 
  cork 
  upon 
  it 
  and 
  

   applies 
  its 
  vapour 
  thereto, 
  one 
  cannot 
  observe 
  that 
  the 
  cork 
  is 
  at 
  all 
  

   affected 
  thereby. 
  But 
  not 
  only 
  this, 
  one 
  can 
  get 
  the 
  very 
  reverse 
  of 
  

   repulsion 
  during 
  the 
  emission 
  of 
  vapour 
  ; 
  thus, 
  upon 
  either 
  turpentine 
  or 
  

   kerosene 
  a 
  small 
  piece 
  of 
  cork 
  is 
  placed, 
  and 
  a 
  rod 
  moistened 
  with 
  ammonia 
  

   is 
  then 
  brought 
  to 
  within 
  about 
  half 
  an 
  inch 
  of 
  it, 
  v/hen 
  the 
  cork 
  may 
  

   be 
  observed 
  to 
  positively 
  rush 
  to 
  the 
  rod 
  and 
  follow 
  it 
  about 
  as 
  obediently 
  

   as 
  a 
  needle 
  can 
  respond 
  to 
  the 
  movements 
  of 
  a 
  magnet.''' 
  

  

  Taken 
  as 
  a 
  whole, 
  the 
  results 
  which 
  I 
  have 
  just 
  described 
  or 
  exliibited 
  

   to 
  you, 
  do, 
  as 
  I 
  conceive, 
  indisputably 
  show 
  that 
  this 
  recession 
  of 
  particles 
  

   under 
  the 
  influence 
  of 
  camphor 
  is, 
  appearances 
  notwithstanding, 
  not 
  due 
  to 
  

   the 
  direct 
  impingement 
  of 
  vapour 
  on 
  them, 
  but 
  rather 
  to 
  some 
  effect 
  follow- 
  

   ing 
  thereupon 
  ; 
  and 
  it 
  seems 
  therefore 
  necessarily 
  to 
  follow 
  that 
  the 
  move- 
  

   ments 
  of 
  this 
  substance 
  (camphor) 
  on 
  water, 
  are 
  also 
  not 
  the 
  direct 
  result 
  of 
  

   impingement, 
  but 
  the 
  result 
  of 
  something 
  which 
  follows 
  it. 
  

  

  And 
  now, 
  with 
  the 
  popular 
  theory 
  thus 
  disproved 
  before 
  you, 
  it 
  may 
  

   occur 
  to 
  some 
  one 
  here, 
  as 
  it 
  did 
  to 
  me, 
  that 
  possibly 
  these 
  movements 
  of 
  

  

  * 
  Volatile 
  acids, 
  also 
  water, 
  applied 
  in 
  this 
  way 
  have 
  the 
  reverse 
  effect, 
  while 
  tur- 
  

   pentine 
  is 
  neutral. 
  The 
  rod 
  alone, 
  if 
  warm, 
  has 
  also 
  an 
  apparent 
  repulsive 
  effect 
  on 
  

   ■ 
  the 
  corlii. 
  

  

  