﻿THE 
  ^-"^^C? 
  

  

  LONDON, 
  EDINBURGH, 
  and 
  DUBLIN 
  

  

  PHILOSOPHICAL 
  MAGAZINE 
  

  

  AND 
  

  

  JOURNAL 
  OF 
  SCIENCK 
  

  

  [SIXTH 
  SERIES.] 
  

  

  SEP 
  1 
  EMBER 
  1909. 
  

  

  XLIII. 
  The 
  Ions 
  of 
  Gases. 
  By 
  William 
  Sutherland 
  ^. 
  

  

  RE(JEXT 
  accumulations 
  o£ 
  experimental 
  work 
  on 
  this 
  

   subject 
  show 
  the 
  need 
  of 
  a 
  more 
  comprehensive 
  theory 
  

   than 
  has 
  yet 
  been 
  advanced. 
  The 
  following 
  is 
  an 
  attempt 
  to 
  

   state 
  the 
  fundamentals 
  of 
  a 
  theory 
  wide 
  enough 
  to 
  contain 
  

   the 
  chief 
  phenomena 
  now 
  known. 
  The 
  simplest 
  theoretical 
  

   ion 
  in 
  a 
  gas 
  is 
  an 
  atom 
  charged 
  with 
  an 
  electron, 
  just 
  as 
  in 
  

   elpctrolytic 
  solutions. 
  But 
  the 
  calculations 
  of 
  J. 
  J. 
  Thom- 
  

   son, 
  Langevin, 
  and 
  others, 
  seem 
  to 
  show 
  that 
  the 
  smallest 
  

   ions 
  in 
  gases 
  consist 
  of 
  a 
  few 
  molecules, 
  say 
  two 
  or 
  three. 
  

   P. 
  Phillips 
  in 
  his 
  experiments 
  on 
  Ionic 
  Velocities 
  in 
  Air 
  

   (Proc. 
  Roy. 
  Soc. 
  Ixxviii. 
  1906, 
  p. 
  167), 
  with 
  a 
  wide 
  range 
  

   of 
  temperature 
  finds 
  the 
  number 
  of 
  molecules 
  in 
  a 
  gaseous 
  

   ion 
  to 
  vary 
  apparently 
  with 
  the 
  temperature. 
  It 
  v,'ill 
  be 
  

   shown 
  immediately 
  that 
  this 
  variation 
  of 
  the 
  size 
  of 
  the 
  

   small 
  ion 
  in 
  gases 
  is 
  only 
  apparent, 
  that 
  the 
  experimental 
  

   ion 
  is 
  the 
  simple 
  ion 
  of 
  theory 
  and 
  electrolysis, 
  and 
  that 
  the 
  

   seeming 
  change 
  of 
  size 
  is 
  due 
  to 
  the 
  same 
  cause 
  as 
  the 
  seem- 
  

   ing 
  change 
  of 
  size 
  of 
  molecules 
  with 
  temperature 
  in 
  the 
  

   viscosity 
  of 
  gases 
  ai)d 
  allied 
  phenomena 
  before 
  the 
  effects 
  of 
  

   cohesional 
  force 
  were 
  allowed 
  for 
  in 
  the 
  kinetic 
  theory 
  of 
  

   gases. 
  When 
  the 
  electric 
  force 
  of 
  the 
  simple 
  ion 
  in 
  a 
  gas 
  is 
  

   introduced 
  into 
  the 
  calculation 
  of 
  the 
  ionic 
  mobilities 
  to 
  be 
  

   expected 
  at 
  the 
  different 
  temperatures 
  in 
  the 
  experiments 
  o£ 
  

  

  * 
  Communicated 
  by 
  the 
  Author. 
  

   Phil. 
  Mag. 
  S. 
  6. 
  Vol. 
  18. 
  No. 
  105. 
  Sept. 
  1909. 
  2 
  A 
  

  

  