﻿the 
  Ions 
  of 
  Gases. 
  347 
  

  

  right 
  side 
  equal 
  to 
  the 
  left. 
  It 
  shows 
  that 
  Wellisch's 
  theory- 
  

   does 
  not 
  give 
  the 
  right 
  reason 
  for 
  the 
  difficulty. 
  The 
  fric- 
  

   tional 
  resistance 
  expressed 
  by 
  the 
  right 
  side 
  of 
  (10) 
  must 
  be 
  

   made 
  8' 
  6 
  times 
  as 
  great 
  to 
  make 
  the 
  dynamical 
  theory 
  of 
  the 
  

   small 
  ions 
  in 
  air 
  correct. 
  The 
  additional 
  resistance 
  is 
  in- 
  

   troduced 
  if 
  we 
  take 
  account 
  of 
  the 
  two 
  new 
  types 
  of 
  viscosity 
  

   (Phil. 
  Mag. 
  [6] 
  xiv. 
  p. 
  1) 
  shown 
  to 
  be 
  fundamental 
  for 
  the 
  

   motion 
  of 
  ions 
  in 
  liquids. 
  We 
  shall 
  find 
  these 
  to 
  be 
  as 
  

   important 
  in 
  the 
  dynamical 
  theory 
  of 
  ions 
  in 
  gases. 
  The 
  

   first 
  of 
  these 
  viscosities, 
  whose 
  coefficient 
  is 
  f, 
  has 
  its 
  origin 
  

   in 
  the 
  mutual 
  potential 
  energy 
  of 
  the 
  opposite 
  electron 
  

   charges 
  of 
  the 
  two 
  kiuds 
  of 
  ion. 
  The 
  second 
  has 
  its 
  origin 
  

   in 
  the 
  mutual 
  potential 
  energy 
  of 
  an 
  ionic 
  charge, 
  and 
  the 
  

   polarization 
  which 
  it 
  induces 
  in 
  the 
  neighbouring 
  molecules- 
  

   of 
  the 
  surrounding 
  medium. 
  Its 
  coefficient 
  was 
  denoted 
  

   by 
  0. 
  As 
  the 
  causes 
  producing 
  ionization 
  and 
  maintaining 
  

   it 
  in 
  a 
  liquid 
  solution 
  are 
  different 
  from 
  those 
  acting 
  in 
  a 
  

   gas, 
  it 
  will 
  be 
  necessary 
  to 
  make 
  a 
  special 
  calculation 
  for 
  f 
  

   and 
  6 
  in 
  a 
  gas, 
  though 
  similar 
  to 
  that 
  furnished 
  for 
  liquid 
  

   solutions. 
  

  

  In 
  the 
  paper 
  just 
  mentioned 
  it 
  is 
  shown 
  that 
  if 
  q 
  positive 
  

   and 
  q 
  negative 
  ions 
  of 
  charge 
  e 
  are 
  nniformly 
  distributed 
  

   through 
  a 
  cm.^, 
  of 
  a 
  medium 
  of 
  dielectric 
  capacity 
  K, 
  they 
  

   possess 
  a 
  rigidity 
  

  

  3K" 
  

  

  N 
  — 
  — 
  e^o^'^ 
  

  

  If 
  they 
  are 
  strained 
  by 
  electric 
  force 
  so 
  that 
  each 
  positive 
  

   electron 
  is 
  displaced 
  in 
  one 
  direction 
  and 
  each 
  negative 
  in 
  

   the 
  opposite, 
  a 
  corresponding 
  stress 
  is 
  developed. 
  Now 
  the 
  

   presence 
  of 
  molecules 
  may 
  cause 
  this 
  strain 
  to 
  relax 
  by 
  

   forcing 
  the 
  ions 
  back 
  to 
  uniform 
  distribution 
  ; 
  they 
  will 
  

   convert 
  the 
  rigidity 
  N 
  into 
  a 
  viscosity 
  NT, 
  where 
  T 
  is 
  the 
  

   time 
  required 
  to 
  reduce 
  the 
  stress 
  to 
  1/e 
  of 
  its 
  initial 
  amount, 
  

   e 
  being 
  the 
  base 
  of 
  natural 
  logarithms. 
  When 
  the 
  ions 
  are 
  

   those 
  of 
  an 
  electrolytic 
  solution, 
  the 
  relaxing 
  action 
  of 
  the 
  

   molecules 
  of 
  solvent 
  is 
  due 
  to 
  their 
  ionizing 
  force, 
  that 
  force 
  

   which 
  pulls 
  the 
  ions 
  of 
  the 
  solute 
  apart 
  and 
  keeps 
  them 
  

   uniformly 
  distributed. 
  In 
  the 
  paper 
  just 
  cited 
  this 
  ionizing 
  

   force 
  is 
  taken 
  to 
  be 
  proportional 
  to 
  q^^^ 
  as 
  it 
  overcomes 
  the 
  

   direct 
  electric 
  attraction 
  between 
  neighbour 
  opposite 
  ions. 
  

   But 
  in 
  a 
  gas 
  we 
  do 
  not 
  regard 
  the 
  molecules 
  as 
  direct 
  ionizers. 
  

   What 
  then 
  are 
  the 
  actions 
  in 
  a 
  gas 
  tending 
  to 
  keep 
  ions 
  

   uniformly 
  distributed 
  ? 
  The 
  chief 
  one 
  is 
  the 
  following. 
  

   According 
  to 
  the 
  principle 
  of 
  the 
  electric 
  origin 
  of 
  molecular 
  

   attraction 
  each 
  molecule 
  behaves 
  like 
  an 
  electrically 
  polarized 
  

  

  