﻿Interionic 
  Force 
  in 
  Electrolytes. 
  363 
  

  

  in 
  this 
  way 
  that 
  a 
  satisfactory 
  explanation 
  of 
  the 
  failure 
  of 
  

   the 
  mass 
  action 
  law 
  can 
  be 
  got. 
  On 
  the 
  other 
  hand, 
  the 
  

   idea 
  of 
  the 
  molecular 
  pressure 
  of 
  a 
  pair 
  of 
  associated 
  ions 
  

   seems 
  also 
  necessary 
  to 
  obtain 
  an 
  accurate 
  agreement 
  with 
  

   the 
  experimental 
  equality 
  of 
  the 
  freezing-point 
  and 
  con- 
  

   ductivity 
  variations. 
  Both 
  conditions 
  will 
  be 
  satisfied 
  if 
  

   the 
  law 
  of 
  interionic 
  force 
  be 
  such 
  as 
  practically 
  to 
  confine 
  

   the 
  electrical 
  attraction 
  to 
  pairs 
  of 
  nearest 
  ions. 
  Now, 
  the 
  

   view 
  that 
  in 
  an 
  electrolyte 
  each 
  + 
  ion 
  attracts 
  every 
  — 
  ion 
  

   and 
  repels 
  every 
  + 
  ion 
  is 
  undoubtedly 
  a 
  highly 
  artificial 
  

   one. 
  How 
  artificial 
  it 
  is 
  is 
  made 
  evident 
  by 
  observing 
  that 
  

   the 
  mutual 
  energy 
  of 
  an 
  ion 
  with 
  others 
  would 
  have 
  to 
  be 
  

   expressed 
  as 
  a 
  sum 
  of 
  hundreds 
  of 
  terms 
  before 
  any 
  close 
  

   approximation 
  to 
  its 
  value 
  could 
  be 
  obtained. 
  These 
  repre- 
  

   sent 
  the 
  mutual 
  energies 
  with 
  the 
  nearest 
  ion, 
  the 
  next 
  

   nearest, 
  the 
  third 
  nearest, 
  &c, 
  and 
  form 
  terms 
  which 
  partly 
  

   cancel 
  each 
  other 
  as 
  the 
  successive 
  ions 
  are 
  + 
  and 
  — 
  . 
  

   It 
  is 
  unlikely 
  that 
  this 
  state 
  of 
  things 
  represents 
  a 
  physical 
  

   reality. 
  Indeed, 
  the 
  assumption 
  on 
  which 
  it 
  is 
  based, 
  that 
  

   the 
  action 
  of 
  the 
  water 
  molecules 
  can 
  be 
  simulated 
  by 
  that 
  

   of 
  a 
  continuous 
  medium 
  of 
  S.I.C. 
  the 
  same 
  as 
  that 
  of 
  water 
  in 
  

   mass, 
  is 
  hardly 
  likely 
  to 
  be 
  true. 
  It 
  is 
  probably 
  a 
  good 
  deal 
  

   nearer 
  to 
  the 
  truth 
  to 
  imagine 
  surrounding 
  each 
  ion 
  a 
  

   number 
  of 
  polarized 
  water 
  molecules 
  which 
  tend 
  to 
  form 
  

   chains 
  linking 
  together 
  pairs 
  of 
  temporarily 
  nearest 
  oppo- 
  

   sitely 
  charged 
  ions. 
  Such 
  an 
  action 
  would 
  not 
  be 
  the 
  same 
  

   as 
  that 
  of 
  a 
  uniform 
  medium; 
  it 
  would 
  be 
  more 
  analogous 
  

   to 
  the 
  action 
  of 
  iron 
  filings 
  in 
  forming 
  chains 
  between 
  two 
  

   magnetic 
  poles. 
  The 
  general 
  effect 
  would 
  be 
  to 
  increase 
  the 
  

   attraction 
  between 
  an 
  ion 
  and 
  the 
  nearest 
  one 
  to 
  it 
  of 
  unlike 
  

   sign 
  at 
  the 
  expense 
  of 
  the 
  attraction 
  of 
  more 
  distant 
  ones, 
  

   which 
  latter 
  might 
  well 
  be 
  negligible 
  in 
  consequence. 
  

  

  The 
  view 
  of 
  the 
  constitution 
  of 
  an 
  electrolyte 
  which 
  is 
  

   thus 
  attained 
  will 
  satisfy 
  both 
  the 
  requirements 
  mentioned 
  

   above, 
  which 
  are 
  essential 
  to 
  a 
  satisfactory 
  theory. 
  On 
  it 
  

   we 
  may 
  imagine 
  all 
  the 
  ions 
  divided 
  into 
  pairs 
  formed 
  of 
  ions 
  

   which 
  are 
  temporarily 
  nearest 
  together, 
  the 
  individuals 
  of 
  

   each 
  pair 
  undergoing 
  continual 
  change. 
  Between 
  the 
  ions 
  

   of 
  each 
  pair 
  electrical 
  force 
  exists, 
  which 
  in 
  many 
  wavs 
  is 
  

   similar 
  to 
  a 
  chemical 
  bond, 
  but 
  is 
  different 
  in 
  others. 
  Thus, 
  

   with 
  chemical 
  association, 
  an 
  ion 
  is 
  either 
  free 
  or 
  combined, 
  

   it 
  cannot 
  be 
  both 
  together, 
  but 
  here 
  it 
  possesses 
  simultaneously 
  

   characteristics 
  of 
  both 
  conditions. 
  The 
  ions 
  in 
  each 
  pair, 
  

   for 
  instance, 
  will 
  be 
  separated 
  spatially 
  from 
  each 
  other 
  

   nearly 
  as 
  widely 
  as 
  if 
  they 
  were 
  quite 
  free 
  ; 
  they 
  are 
  free 
  

   (e. 
  g. 
  to 
  carry 
  current 
  or 
  exert 
  ionic 
  pressure) 
  in 
  a 
  fraction 
  

  

  