﻿TTIE 
  

   LONDON, 
  EDINBURGH, 
  and 
  DUBLIN 
  

  

  PHILOSOPHICAL 
  MAGAZINE 
  

  

  AND 
  

  

  JOURNAL 
  OF 
  SCIENCE. 
  

  

  [FIFTH 
  SERIES.] 
  

  

  ju. 
  JUN 
  10 
  1898 
  sJ 
  

  

  JUNE 
  1898. 
  V/ 
  

  

  L. 
  Applications 
  of 
  Diffusion 
  to 
  Conducting 
  Gases. 
  By 
  John 
  

   S. 
  Townsend, 
  M.A., 
  Cavendish 
  Laboratory, 
  Cambridge*. 
  

  

  THERE 
  are 
  many 
  phenomena 
  connected 
  with 
  charged 
  and 
  

   conducting 
  gases 
  which 
  can 
  be 
  explained 
  by 
  diffusion. 
  

   Before 
  proceeding 
  to 
  its 
  application 
  to 
  these 
  gases 
  it 
  is 
  

   necessary 
  to 
  solve 
  some 
  problems 
  which 
  apply 
  not 
  only 
  to 
  

   conducting 
  gases, 
  but 
  also 
  to 
  gases 
  in 
  general. 
  The 
  question 
  

   with 
  which 
  it 
  is 
  proposed 
  to 
  deal 
  may 
  be 
  stated 
  thus 
  : 
  — 
  If 
  

   there 
  are 
  two 
  gases, 
  A 
  and 
  B, 
  contained 
  inside 
  a 
  vessel 
  the 
  

   walls 
  of 
  which 
  absorb 
  A, 
  what 
  quantity 
  of 
  A 
  will 
  remain 
  

   unabsorbed 
  and 
  be 
  left 
  distributed 
  throughout 
  B 
  inside 
  the 
  

   vessel 
  after 
  a 
  given 
  time 
  has 
  elapsed 
  ? 
  

  

  The 
  first 
  section 
  deals 
  with 
  the 
  solution 
  of 
  this 
  problem 
  for 
  

   the 
  three 
  particular 
  cases 
  where 
  the 
  boundary 
  consists 
  of 
  a 
  

   pair 
  of 
  parallel 
  planes, 
  a 
  cylinder, 
  and 
  a 
  sphere 
  respectively. 
  

   It 
  will 
  be 
  supposed 
  that 
  the 
  absorption 
  of 
  the 
  gas 
  A 
  by 
  the 
  

   sides 
  of 
  the 
  vessel 
  is 
  so 
  complete 
  as 
  to 
  reduce 
  the 
  pressure 
  of 
  

   A 
  to 
  zero 
  at 
  the 
  surface. 
  In 
  order 
  to 
  obtain 
  solutions 
  that 
  

   will 
  apply 
  to 
  cases 
  where 
  the 
  pressure 
  at 
  the 
  surface 
  is 
  a 
  small 
  

   fixed 
  value 
  it 
  will 
  suffice 
  to 
  substitute 
  p 
  +p' 
  for 
  p 
  in 
  the 
  solu- 
  

   tions 
  obtained 
  on 
  the 
  assumption 
  thatp=0 
  at 
  the 
  surface. 
  

  

  In 
  order 
  that 
  the 
  effect 
  of 
  gravity 
  may 
  not 
  disturb 
  the 
  

   distribution 
  of 
  the 
  gases 
  it 
  will 
  be 
  supposed 
  that 
  the 
  quantity 
  

   of 
  A 
  is 
  small 
  compared 
  with 
  that 
  of 
  B. 
  

  

  The 
  second 
  section 
  deals 
  with 
  the 
  application 
  of 
  these 
  

   results 
  to 
  the 
  cases 
  of 
  charged 
  and 
  conducting 
  gases. 
  

  

  * 
  Communicated 
  by 
  Prof. 
  J. 
  J. 
  Thomson, 
  F.R.S. 
  

   Phil. 
  Mag. 
  S. 
  5. 
  Vol. 
  45. 
  No. 
  277. 
  June 
  1898. 
  2 
  K 
  

  

  