﻿and 
  Chemical 
  Reactions 
  in 
  Heterogeneous 
  Systems. 
  551 
  

  

  amounts 
  to 
  the 
  same/'' 
  This 
  says 
  in 
  so 
  many 
  words 
  what 
  

   Bruner 
  and 
  ToUoczko 
  told 
  us 
  before 
  {Zeitsch. 
  fiir 
  anorg. 
  

   CJiemie, 
  1901, 
  p. 
  328) 
  that 
  '^ 
  the 
  saturated 
  solution 
  at 
  the 
  

   surface 
  of 
  the 
  solid 
  is 
  formed 
  instantaneously/' 
  Now, 
  this 
  

   fundamental 
  assumption 
  of 
  Nernst 
  is 
  quite 
  wrong, 
  as 
  can 
  be 
  

   seen 
  from 
  the 
  following 
  : 
  when 
  we 
  mix 
  two 
  liquids, 
  say 
  in 
  

   equal 
  parts, 
  and 
  a 
  reaction 
  goes 
  on 
  between 
  them, 
  we 
  have, 
  

   in 
  the 
  first 
  instance, 
  a 
  certain 
  difference 
  of 
  chemical 
  potentials 
  

   acting 
  between 
  the 
  molecules 
  in 
  the 
  system, 
  since 
  otherwise 
  

   no 
  reaction 
  would 
  go 
  on 
  ; 
  secondly, 
  the 
  acting 
  molecules 
  can 
  

   only 
  be 
  removed 
  from 
  one 
  another 
  by 
  double 
  the 
  distance 
  of 
  

   the 
  spheres 
  of 
  the 
  molecules 
  themselves. 
  According 
  to 
  

   Nernst 
  all 
  such 
  reactions, 
  such 
  as 
  solution 
  of 
  anilin 
  in 
  acetic 
  

   acid, 
  &c. 
  ought 
  to 
  go 
  on 
  with 
  an 
  infinitely 
  great 
  speed 
  in 
  

   the 
  homogeneous 
  system. 
  

  

  Xow, 
  a 
  very 
  great 
  number 
  of 
  reactions 
  in 
  organic 
  chemistry 
  

   are 
  carried 
  out 
  by 
  mixing 
  two 
  liquids 
  together 
  in 
  the 
  above 
  

   manner, 
  and 
  all 
  organic 
  reactions, 
  with 
  few 
  exceptions, 
  

   belong 
  to 
  the 
  slow, 
  often 
  to 
  the 
  extremely 
  slow, 
  not 
  to 
  the 
  

   instantaneous, 
  reactions. 
  On 
  the 
  other 
  hand, 
  many 
  reactions, 
  

   even 
  in 
  very 
  dilute 
  solutions, 
  go 
  on 
  almost 
  instantaneously, 
  

   though 
  the 
  reacting 
  molecules 
  in 
  the 
  solution 
  are 
  very 
  

   considerably 
  removed 
  from 
  one 
  another. 
  This 
  is 
  so 
  well 
  

   known 
  to 
  every 
  chemist, 
  that 
  I 
  need 
  not 
  dwell 
  upon 
  it 
  any 
  

   longer 
  to 
  show 
  the 
  utter 
  futility 
  of 
  the 
  above 
  assumption. 
  

   Xernst's 
  assumption 
  that 
  ^'infinitely 
  great 
  forces" 
  are 
  acting 
  

   between 
  different 
  parts 
  of 
  the 
  heterogeneous 
  system, 
  when 
  

   it 
  is 
  not 
  in 
  equilibrium, 
  is 
  therefore 
  absolutely 
  unsupported 
  

   by 
  daily 
  experience. 
  Here 
  we 
  have 
  to 
  deal 
  with 
  ordinary 
  

   solution 
  of 
  solid 
  salts, 
  where 
  no 
  electrostatic 
  forces 
  come 
  

   into 
  play, 
  and 
  consequently 
  where 
  the 
  osmotic 
  pressure 
  of 
  

   the 
  solution 
  at 
  equilibrium 
  equals 
  the 
  total 
  solution 
  pressure 
  

   of 
  the 
  solid. 
  We 
  shall 
  see 
  later 
  on 
  that 
  the 
  forces 
  coming 
  

   into 
  consideration 
  here 
  for 
  the 
  different 
  kinds 
  of 
  reaction 
  

   are 
  not 
  " 
  infinitely 
  great,'"' 
  but 
  of 
  measurable, 
  and 
  often 
  of 
  

   very 
  small 
  values 
  indeed. 
  So 
  far 
  I 
  much 
  prefer 
  the 
  less 
  

   detailed 
  views 
  of 
  Bruner 
  and 
  Tolloczko, 
  who 
  speak 
  of 
  

   ^' 
  instantaneous 
  reactions,^' 
  without 
  binding 
  themselves 
  to 
  

   " 
  infinitely 
  great 
  forces. 
  '"' 
  

  

  (Jj) 
  I 
  now 
  turn 
  my 
  attention 
  to 
  Nernst 
  and 
  Brunner's 
  

   support 
  of 
  the 
  hypothesis 
  that 
  at 
  the 
  surface 
  of 
  the 
  solid 
  a 
  

   saturated 
  solution 
  is 
  formed, 
  which 
  is 
  only 
  capable 
  of 
  passing 
  

   into 
  the 
  region 
  of 
  the 
  action 
  of 
  the 
  stirrer 
  by 
  diffusion. 
  My 
  

   question 
  is, 
  where 
  is 
  the 
  proof 
  for 
  the 
  same 
  ? 
  What 
  is 
  there 
  to 
  

   prevent 
  the 
  liquids 
  from 
  passing 
  to 
  the 
  very 
  solid 
  ? 
  In 
  ray 
  

   opinion 
  neither 
  their 
  deduction 
  of 
  the 
  equation 
  on 
  p. 
  63, 
  nor 
  

  

  