﻿284 
  Messrs. 
  Gill 
  and 
  Pidduck 
  on 
  the 
  Genesis 
  of 
  Ions 
  

  

  The 
  corresponding 
  curves 
  for 
  air 
  have 
  been 
  included 
  for 
  

   comparison, 
  and 
  it 
  will 
  be 
  seen 
  that 
  a 
  and 
  are 
  both 
  greater 
  

   for 
  argon 
  under 
  the 
  same 
  conditions 
  of 
  pressure 
  and 
  electric 
  

   force. 
  

  

  3. 
  The 
  experimental 
  difficulties 
  connected 
  with 
  the 
  manipu- 
  

   lation 
  of 
  helium 
  were 
  greater. 
  The 
  first 
  experiments 
  were 
  

   made 
  on 
  a 
  purchased 
  sample, 
  and 
  on 
  a 
  larger 
  quantity 
  which 
  

   was 
  kindly 
  given 
  by 
  Professor 
  .Ramsay 
  containing 
  at 
  least 
  

   98 
  per 
  cent, 
  of 
  helium. 
  

  

  As 
  the 
  theory 
  holds 
  equally 
  well 
  for 
  mixtures 
  as 
  for 
  pure 
  

   gases, 
  we 
  give 
  here 
  the 
  results 
  of 
  the 
  experiments. 
  The 
  gas 
  

   was 
  afterwards 
  purified 
  and 
  similar 
  experiments 
  were 
  made, 
  

   which 
  gave 
  much 
  higher 
  numbers 
  for 
  /3 
  and 
  lower 
  sparking 
  

   potentials. 
  The 
  experiments 
  on 
  the 
  slightly 
  impure 
  gas 
  are 
  

   given 
  in 
  the 
  following 
  tables, 
  as 
  they 
  are 
  of 
  interest 
  in 
  showing 
  

   the 
  effects 
  of 
  small 
  impurities 
  in 
  the 
  case 
  of 
  helium 
  by 
  com- 
  

   parison 
  with 
  the 
  later 
  experiments, 
  and 
  also 
  in 
  showing 
  that 
  

   the 
  same 
  theory 
  holds 
  good 
  for 
  this 
  gas. 
  

  

  Table 
  YL 
  — 
  Helium, 
  pressure 
  13 
  mms. 
  

  

  d 
  

  

  •2. 
  

  

  •4. 
  

  

  •6. 
  

  

  

  X=404 
  q 
  

  

  a 
  = 
  9-32 
  

  

  650 
  

  

  44-8 
  

  

  531 
  

  

  6-50 
  

  

  44-8 
  

  

  531 
  

  

  /3=-0179 
  

  

  Table 
  YII 
  

  

  , 
  — 
  Helium, 
  

  

  pressure 
  10 
  

  

  mms. 
  

  

  

  d 
  

  

  ■1. 
  ( 
  -2. 
  

  

  •3. 
  

  

  •4. 
  

  

  •5. 
  

  

  •6. 
  

  

  

  X-101 
  q 
  

  

  113 
  

  

  1-27 
  

  

  1-43 
  

  

  

  

  

  a— 
  1-19 
  n 
  

  

  1-13 
  

  

  1-27 
  

  

  1-43 
  

  

  

  

  

  

  X=385 
  q 
  

  

  2-61 
  

   2-45 
  

  

  5-84 
  

  

  14-8 
  

  

  38-3 
  

  

  123 
  

  

  503 
  

  

  a 
  =8-95 
  

  

  603 
  

  

  15-1 
  

  

  39-2 
  

  

  114 
  

  

  515 
  

  

  /3=-0252 
  n 
  

  

  Table 
  VIII. 
  — 
  Helium, 
  pressure 
  8 
  mms. 
  

  

  d 
  

  

  •2. 
  

  

  '4. 
  

  

  •5. 
  

  

  •7. 
  

  

  •8. 
  

  

  

  

  

  

  X=305 
  q 
  

  

  a 
  =6-91 
  

  

  /3 
  = 
  -0206 
  n 
  

  

  4-04 
  

  

  17-2 
  | 
  34-4 
  

  

  175 
  

  

  8160 
  

  

  399 
  

  

  16-4 
  

  

  343 
  

  

  195 
  

  

  9210 
  

  

  