﻿and 
  Chemical 
  Reactions 
  in 
  Heterogeneous 
  Systems. 
  559 
  

  

  as 
  given 
  by 
  myself, 
  are 
  very 
  clear 
  and 
  simple, 
  are 
  almost 
  

   axiomatic 
  in 
  their 
  character. 
  

  

  I 
  return 
  to 
  the 
  argument 
  I 
  have 
  already 
  given 
  in 
  the 
  Rep. 
  

   Brit. 
  Assoc. 
  Liverpool, 
  1896, 
  in 
  connexion 
  with 
  Co. 
  My 
  

   equation 
  is 
  shown 
  to 
  hold 
  for 
  all 
  molecular 
  reactions, 
  including 
  

   such 
  reactions 
  as 
  the 
  transformation 
  of 
  ice 
  into 
  water, 
  water 
  

   into 
  ice, 
  &c., 
  where 
  concentration 
  does 
  not 
  come 
  into 
  con- 
  

   sideration. 
  It 
  is 
  evident 
  that 
  a 
  law 
  of 
  such 
  a 
  generality 
  cannot 
  

   lind 
  an 
  e.cplanation 
  in 
  diffusion^ 
  w^hich 
  can 
  have 
  only 
  a 
  limited 
  

   application. 
  This 
  is 
  evident 
  joroo/ 
  that 
  there 
  is 
  no 
  necessity 
  

   whatever 
  in 
  diffusion 
  conceptions 
  to 
  explain 
  the 
  meaning 
  of 
  

   my 
  equation, 
  and 
  that 
  to 
  give 
  the 
  correct 
  natural 
  interpre- 
  

   tation 
  to 
  its 
  meaning, 
  we 
  must 
  take 
  as 
  a 
  basis 
  the 
  general 
  

   features 
  underlying 
  all 
  of 
  them, 
  as 
  I 
  did 
  in 
  my 
  papers 
  and 
  

   here, 
  and 
  not 
  follow 
  the 
  particular 
  line 
  of 
  diffusion. 
  

  

  The 
  analogy 
  between 
  the 
  equation 
  for 
  velocity 
  of 
  solution 
  

   of 
  salt 
  with 
  the 
  equation 
  for 
  diffusion 
  evidently 
  seemed 
  to 
  

   Noyes 
  and 
  Whitney, 
  Bruner 
  and 
  Tolloczko, 
  Nernst 
  and 
  

   Brunner 
  peculiar 
  and 
  led 
  them 
  to 
  try 
  to 
  identify 
  them 
  and 
  to 
  

   aday)t 
  the 
  conceptions 
  accordingly. 
  

  

  This 
  coincidence 
  may 
  appeal 
  to 
  some 
  as 
  remarkable, 
  but 
  is 
  

   of 
  no 
  value 
  so 
  long 
  as 
  the 
  physical 
  constants 
  do 
  not 
  j^rove 
  this 
  

   identity, 
  because 
  buoyancy 
  is 
  also 
  regulated 
  by 
  a 
  law 
  of 
  a 
  

   similar 
  nature, 
  so 
  is 
  the 
  law 
  of 
  Newton 
  for 
  cooling 
  &c. 
  Why 
  

   not 
  identify 
  velocity 
  of 
  molecular 
  reaction 
  with 
  the 
  law 
  of 
  

   Newton 
  ? 
  With 
  many 
  assumptions, 
  plenty 
  of 
  hypothesis, 
  

   and 
  no 
  experimental 
  proof, 
  a 
  much 
  more 
  fascinating 
  theory 
  

   could 
  be 
  developed 
  here. 
  But, 
  as 
  already 
  explained 
  in 
  my 
  

   paper 
  (Phil. 
  Mag. 
  July 
  1901) 
  in 
  great 
  detail, 
  there 
  is 
  no 
  

   more 
  and 
  no 
  less 
  analogy 
  between 
  all 
  these 
  phenomena 
  (speed 
  

   of 
  molecular 
  reaction, 
  diffusion, 
  buoyancy, 
  conduction 
  of 
  

   heat), 
  they 
  all 
  have 
  in 
  common, 
  that, 
  v/henever 
  a 
  kind 
  

   of 
  energy 
  (chemical, 
  thermal, 
  &c.) 
  is 
  removed 
  from 
  the 
  

   state 
  of 
  equilibrium, 
  the 
  speed 
  with 
  which 
  it 
  strives 
  to 
  attain 
  

   the 
  same 
  is 
  directly 
  proportional 
  to 
  its 
  remoteness 
  at 
  the 
  time 
  

   T 
  from 
  its 
  point 
  of 
  equilibrium. 
  This, 
  nevertheless, 
  does 
  not 
  

   make 
  all 
  these 
  phenomena 
  identical. 
  

  

  (/) 
  Let 
  us 
  now 
  assume 
  for 
  a 
  moment 
  that 
  the 
  speed 
  of 
  

   solution 
  is 
  regulated 
  by 
  

  

  | 
  = 
  |S(C-.) 
  or 
  ^(C-e), 
  forS 
  = 
  l. 
  

  

  Now 
  the 
  velocity 
  of 
  evaporation 
  also 
  follows 
  my 
  equation, 
  and 
  

   the 
  well 
  established 
  thermodynamic 
  analogy 
  between 
  solution 
  

   and 
  evaporation 
  makes 
  this 
  also 
  self-evident. 
  In 
  case 
  of 
  

   gases 
  the 
  diffusion 
  constant 
  D 
  is 
  about 
  10,000 
  times 
  greater 
  

  

  