﻿Interionic 
  Force 
  in 
  Electrolytes, 
  361 
  

  

  rapidly 
  with 
  the 
  distance 
  *. 
  The 
  law 
  indeed 
  forms 
  a 
  limiting- 
  

   case 
  for 
  which 
  the 
  field 
  of 
  force 
  surrounding 
  each 
  ion 
  is 
  

   infinitely 
  strong 
  but 
  confined 
  to 
  an 
  infinitely 
  thin 
  shell. 
  

   This 
  means 
  that 
  the 
  mass 
  law 
  (4) 
  applies 
  solely 
  to 
  asso- 
  

   ciation 
  and 
  dissociation 
  which 
  is 
  the 
  result 
  of 
  what 
  we 
  may 
  

   call 
  "chemical" 
  forces, 
  using 
  this 
  name 
  to 
  distinguish 
  forces 
  

   of 
  this 
  type 
  from 
  the 
  electrical 
  forces 
  of 
  the 
  free 
  ionic 
  

   charges 
  which 
  fall 
  off 
  very 
  slowly 
  with 
  the 
  distance. 
  If 
  

   association 
  is 
  produced 
  by 
  these 
  (4) 
  will 
  not 
  apply 
  to 
  it. 
  

  

  (2) 
  The 
  preceding 
  conclusion 
  suggests 
  that 
  the 
  failure 
  of 
  

   the 
  mass 
  law 
  may 
  be 
  due 
  to 
  a 
  mistaken 
  view 
  of 
  the 
  nature 
  

   of 
  the 
  interionic 
  forces 
  which 
  cause 
  association. 
  The 
  

   apparent 
  association 
  may 
  be 
  partly 
  — 
  or 
  wholly 
  — 
  due 
  to 
  the 
  

   electric 
  forces. 
  In 
  attempting 
  to 
  investigate 
  this 
  view 
  the 
  

   first 
  difficulty 
  is 
  to 
  know 
  exactly 
  what 
  is 
  the 
  law 
  of 
  force 
  

   between 
  the 
  ions. 
  Are 
  we 
  to 
  assume 
  that 
  every 
  4- 
  ion 
  

   attracts 
  every 
  — 
  ion 
  and 
  repels 
  every 
  + 
  ion 
  in 
  the 
  liquid 
  

   according 
  to 
  the 
  inverse 
  square 
  law 
  ? 
  If 
  the 
  mixture 
  of 
  ions 
  

   were 
  a 
  gaseous 
  one 
  this 
  assumption 
  would 
  presumably 
  be 
  a 
  

   sound 
  one, 
  but 
  its 
  validity 
  is 
  more 
  doubtful 
  in 
  the 
  case 
  of 
  an 
  

   electrolyte, 
  where 
  the 
  forces 
  between 
  the 
  ions 
  are 
  affected 
  by 
  

   the 
  intervening 
  water 
  molecules. 
  As 
  the 
  first 
  step, 
  however, 
  

   it 
  seems 
  the 
  most 
  straightforward 
  assumption 
  to 
  make, 
  and 
  

   in 
  previous 
  papers 
  t 
  I 
  have 
  worked 
  out 
  by 
  what 
  is, 
  I 
  think, 
  

   a 
  strict 
  method, 
  the 
  approximate 
  effect 
  on 
  the 
  osmotic 
  pressure 
  

   of 
  a 
  mixture 
  of 
  ions 
  in 
  which 
  interionic 
  force 
  of 
  this 
  character 
  

   is 
  assumed 
  to 
  exist. 
  The 
  calculation, 
  as 
  might 
  be 
  expected 
  

   from 
  the 
  complexity 
  of 
  the 
  forces, 
  is 
  lengthy 
  and 
  need 
  not 
  

   be 
  further 
  referred 
  to. 
  The 
  net 
  effect 
  of 
  the 
  interionic 
  

   forces 
  was 
  found 
  to 
  give 
  a 
  reduction 
  of 
  the 
  osmotic 
  pressure 
  

   which 
  appears 
  to 
  be 
  in 
  accurate 
  agreement 
  with 
  the 
  experi- 
  

   mentally 
  found 
  results 
  for 
  dilute 
  aqueous 
  solutions 
  of 
  strong 
  

   binary 
  electrolytes. 
  In 
  these 
  cases 
  therefore 
  there 
  is 
  ground 
  

   for 
  believing 
  that 
  " 
  chemical 
  association/' 
  if 
  existent, 
  is 
  

   extremely 
  small, 
  and 
  that 
  the 
  effects 
  observed 
  are 
  due 
  

   entirely 
  to 
  the 
  electrical 
  interionie 
  forces. 
  Before 
  we 
  can 
  

   apply 
  to 
  this 
  view 
  the 
  proposition 
  of 
  the 
  present 
  paper, 
  it 
  is 
  

   necessary 
  to 
  settle 
  the 
  relation 
  in 
  which 
  the 
  free 
  ionic 
  

   pressure 
  p 
  stands 
  to 
  the 
  measured 
  osmotic 
  pressure 
  P. 
  

   Unless 
  they 
  are 
  different 
  from 
  each 
  other, 
  an 
  mequality 
  

  

  * 
  This 
  is 
  the 
  kinetic 
  aspect 
  of 
  the 
  thermodynamical 
  stipulation 
  that 
  

   the 
  o-motic 
  pressures 
  of 
  the 
  ions 
  must 
  obey 
  the 
  perfect 
  gas 
  law. 
  The 
  

   assumption 
  is 
  formally 
  made 
  in 
  Boltzmann's 
  original 
  deduction, 
  and 
  it 
  

   can 
  easily 
  be 
  shown 
  that 
  any 
  other 
  will 
  result 
  in 
  a 
  law 
  different 
  

   from 
  (4). 
  

  

  t 
  Phil. 
  Mag. 
  xxiii. 
  p. 
  551 
  (1912); 
  xxv. 
  p. 
  742 
  (1913). 
  

  

  