﻿888 
  , 
  Messrs. 
  T. 
  H. 
  Laby 
  mid 
  Gr. 
  W. 
  C. 
  Kaye 
  on 
  

  

  complete 
  absorption 
  of 
  a 
  part 
  of 
  the 
  tertiary 
  ft 
  radiation 
  

   occurs 
  more 
  in 
  C0 
  2 
  and 
  in 
  air 
  than 
  in 
  H 
  2 
  . 
  

  

  It 
  is 
  more 
  probable 
  that 
  the 
  soft 
  radiation, 
  whose 
  existence 
  

   we 
  have 
  inferred 
  above, 
  is 
  excited 
  by 
  the 
  absorption 
  of 
  

   f3 
  radiation, 
  haying 
  a 
  velocity 
  about 
  half 
  that 
  of 
  light, 
  than 
  

   that 
  ir 
  is 
  produced 
  directly 
  by 
  the 
  7 
  rays. 
  While 
  it 
  is 
  tertiary 
  

   radiation 
  for 
  our 
  purposes, 
  it 
  should 
  be 
  excited 
  just 
  the 
  same 
  

   when 
  ft 
  rays 
  Broin 
  radium 
  having 
  a 
  velocity 
  of 
  JV 
  are 
  

   absorbed 
  in 
  matter 
  : 
  it 
  would 
  then 
  be 
  called 
  secondary 
  

   radiation. 
  

  

  The 
  above 
  sources 
  of 
  ionization 
  are 
  sufficient 
  to 
  account 
  for 
  

   the 
  experimental 
  results 
  we 
  have 
  obtained, 
  as 
  is 
  shown 
  below. 
  

  

  Hydrogen. 
  — 
  The 
  ionization 
  due 
  to 
  

   I 
  the 
  primary 
  7 
  rays, 
  

   the 
  secondary 
  radiation 
  from 
  the 
  walls, 
  

   1 
  •) 
  the 
  soft 
  tertiary 
  (B 
  radiation, 
  

   will 
  all 
  vary 
  as 
  the 
  pressure 
  in 
  this 
  transparent 
  gas. 
  The 
  

   ionization 
  arising 
  from 
  the 
  secondary 
  /3 
  radiation 
  from 
  the 
  

   hydrogen 
  itself, 
  which 
  varies 
  a^ 
  the 
  square 
  of 
  the 
  pressure, 
  

   maybe 
  neglected. 
  Finally, 
  there 
  is 
  little 
  complete 
  absorption 
  

   of 
  the 
  tertiary 
  /3 
  rays, 
  and 
  thus 
  the 
  ionization 
  in 
  this 
  gas 
  

   varies 
  very 
  nearly 
  as 
  it- 
  pressure. 
  

  

  Air, 
  — 
  The 
  ionization 
  arising 
  Erom 
  (a) 
  and 
  (//) 
  above 
  is 
  

   just 
  as 
  for 
  hydrogen 
  proportional 
  to 
  the 
  pressure 
  : 
  that 
  due 
  

   to 
  the 
  secondary 
  ray- 
  from 
  the 
  gas 
  may 
  be 
  neglected. 
  Some 
  

   of 
  the 
  soft 
  tertiary 
  ft 
  rays 
  are 
  completely 
  absorbed, 
  so 
  that 
  

   the 
  remaining 
  rays 
  contribute 
  for 
  each 
  increment 
  of 
  the 
  

   pressure 
  a 
  decreasing 
  amount 
  of 
  ionization. 
  The 
  sum 
  of 
  

   tli 
  — 
  ionization- 
  would 
  increase 
  less 
  rapidly 
  than 
  directly 
  as 
  

   the 
  pressure, 
  which 
  is 
  in 
  agreement 
  with 
  our 
  observations. 
  

  

  Cm 
  vide. 
  — 
  The 
  ionization 
  is 
  made 
  up 
  in 
  much 
  the 
  

  

  same 
  way 
  as 
  that 
  of 
  air. 
  The 
  effect 
  of 
  the 
  secondary 
  /3 
  

   radiation 
  excited 
  in 
  the 
  C0 
  2 
  itself 
  may 
  need 
  to 
  be 
  taken 
  into 
  

   account: 
  ir 
  contributes 
  ionization 
  varying 
  as 
  the 
  square 
  of 
  

   the 
  pressure. 
  The 
  shape 
  of 
  the 
  C0 
  2 
  curve 
  is 
  consistent 
  with 
  

   the 
  existence 
  of 
  a 
  small 
  proportion 
  of 
  such 
  ionization, 
  for 
  the 
  

   curve 
  exhibits 
  the 
  necessary 
  initial 
  curvature. 
  The 
  absorption 
  

   of 
  the 
  soft 
  tertiary 
  j3 
  rays 
  would 
  be 
  moie 
  marked 
  in 
  C0 
  2 
  

   than 
  in 
  air 
  ; 
  the 
  effect 
  of 
  this 
  is 
  seen 
  in 
  the 
  greater 
  curvature 
  

   of 
  curve 
  C 
  (fig. 
  6). 
  

  

  Since 
  the 
  present 
  experiments 
  were 
  completed 
  Erikson* 
  has 
  

   published 
  in 
  abstract 
  some 
  results 
  on 
  the 
  " 
  Ionization 
  of 
  Gases 
  

   at 
  High 
  Pressures." 
  He 
  found 
  with 
  a 
  constant 
  potential- 
  

   difference 
  between 
  two 
  cylindrical 
  electrodes, 
  that 
  the 
  

  

  * 
  Erikson, 
  Phys. 
  Rev. 
  xxvi. 
  p. 
  199 
  (1908). 
  

  

  