﻿Diffusion 
  to 
  Conducting 
  Gases, 
  479 
  

  

  1*4 
  centimetres 
  per 
  second 
  (J. 
  J. 
  Thomson 
  and 
  E. 
  Rutherford, 
  

   Phil. 
  Mag. 
  Nov. 
  1896 
  ; 
  E. 
  Rutherford, 
  Phil. 
  Mag. 
  Nov. 
  1897). 
  

   The 
  gases 
  evolved 
  from 
  a 
  sulphuric 
  acid 
  electrolyte 
  retain 
  a 
  

   large 
  fraction 
  of 
  their 
  charge 
  after 
  passing 
  through 
  wool 
  or 
  

   bubbling 
  through 
  a 
  liquid, 
  and 
  for 
  the 
  oxygen 
  the 
  velocity 
  of 
  

   the 
  carrier 
  is 
  only 
  2*2 
  x 
  10 
  -4 
  centimetres 
  per 
  second 
  when 
  acted 
  

   on 
  by 
  the 
  same 
  force 
  (John 
  S. 
  Townsend, 
  Phil. 
  Mag. 
  Feb. 
  

   1898). 
  

  

  We 
  have 
  here 
  supposed 
  that 
  e, 
  the 
  charge 
  on 
  the 
  carrier, 
  is 
  

   the 
  same 
  in 
  each 
  case. 
  This 
  assumption 
  is 
  reasonable 
  from 
  

   theoretical 
  considerations, 
  but 
  it 
  has 
  not 
  yet 
  been 
  established 
  

   upon 
  experimental 
  evidence 
  that 
  when 
  an 
  elementary 
  gas 
  

   conducts 
  the 
  carriers 
  have 
  the 
  same 
  charge 
  as 
  the 
  atoms 
  

   carry 
  in 
  electrolysis. 
  Information 
  on 
  this 
  point 
  might 
  be 
  

   gained 
  bv 
  testing 
  experimentally 
  the 
  result 
  obtained 
  in 
  

  

  Many 
  examples 
  of 
  this 
  latter 
  kind 
  are 
  to 
  be 
  found 
  in 
  newly 
  

   prepared 
  gases. 
  In 
  most 
  of 
  these 
  cases 
  it 
  is 
  easy 
  to 
  account 
  

   for 
  the 
  growth 
  of 
  the 
  carrier 
  to 
  a 
  large 
  size 
  owing 
  to 
  the 
  pre- 
  

   sence 
  of 
  gases 
  or 
  vapours 
  which 
  would 
  condense 
  round 
  the 
  

   charge 
  and 
  thus 
  increase 
  the 
  size 
  of 
  the 
  carrier. 
  The 
  velocity 
  

   V 
  would 
  thus 
  be 
  greatly 
  diminished. 
  

  

  When 
  newly 
  prepared 
  gases 
  are 
  evolved 
  from 
  a 
  solution 
  it 
  

   is 
  probable 
  that 
  the 
  electrification 
  is 
  acquired 
  immediately 
  as 
  

   the 
  gas 
  is 
  generated, 
  so 
  that 
  each 
  little 
  bubble 
  of 
  the 
  gas 
  as 
  

   it 
  rises 
  in 
  the 
  liquid 
  contains 
  carriers 
  which 
  are 
  charged. 
  

   Since 
  these 
  bubbles 
  are 
  small 
  it 
  would 
  only 
  require 
  a 
  very 
  

   short 
  time 
  for 
  carriers 
  which 
  diffused 
  rapidly 
  to 
  be 
  com- 
  

   pletely 
  discharged 
  by 
  striking 
  the 
  liquid 
  round 
  the 
  bubble, 
  

   so 
  that 
  in 
  order 
  that 
  an 
  appreciable 
  number 
  of 
  charged 
  

   carriers 
  should 
  escape 
  with 
  the 
  gas 
  from 
  the 
  liquid 
  it 
  is 
  

   necessary 
  to 
  assume 
  that 
  they 
  diffuse 
  slowly, 
  or 
  what 
  amounts 
  

   to 
  the 
  same 
  thing, 
  that 
  they 
  should 
  be 
  large 
  compared 
  with 
  

   molecules. 
  

  

  8. 
  When 
  the 
  number 
  of 
  carriers 
  charged 
  with 
  positive 
  and 
  

   negative 
  electricity 
  respectively 
  is 
  unequal, 
  the 
  electrostatic 
  

   field 
  which 
  is 
  created 
  tends 
  to 
  drive 
  those 
  carriers 
  which 
  

   are 
  in 
  excess 
  towards 
  the 
  walls 
  of 
  the 
  containing 
  vessel. 
  

   This 
  effect 
  is 
  easily 
  calculated 
  for 
  the 
  case 
  where 
  the 
  carriers 
  

   are 
  all 
  charged 
  with 
  electricity 
  of 
  the 
  same 
  sign. 
  Let 
  p 
  be 
  

   the 
  density 
  of 
  electrification, 
  uviv 
  the 
  velocities 
  parallel 
  to 
  

   the 
  axes, 
  and 
  4> 
  the 
  electric 
  potential. 
  

  

  In 
  order 
  to 
  determine 
  the 
  motion 
  we 
  have 
  three 
  equations 
  

  

  of 
  the 
  form 
  

  

  n 
  1 
  dp 
  d(f> 
  

  

  a 
  = 
  -f 
  —e-r~. 
  

  

  n 
  ax 
  ax 
  

  

  