﻿884 
  Prof. 
  McLennan 
  and 
  Mr. 
  Keys 
  on 
  the 
  Electrical 
  

  

  Table 
  III. 
  

   Conductivity 
  imparted 
  to 
  Liquid 
  Air 
  by 
  Alpha 
  Rays. 
  

  

  Potential 
  difference 
  

   applied 
  to 
  electrodes. 
  

  

  Current 
  (rise 
  in 
  volt- 
  

   age) 
  with 
  positive 
  po- 
  

   tential 
  applied 
  to 
  GrlL 
  

  

  Current 
  (rise 
  in 
  volt- 
  

   age) 
  with 
  neg. 
  pot. 
  

   applied 
  to 
  GrH. 
  

  

  Volts. 
  

  

  Rise 
  in 
  volts 
  per 
  min. 
  

  

  Eise 
  in 
  volts 
  per 
  min. 
  

  

  1367 
  

  

  30-35 
  X 
  10 
  " 
  2 
  

  

  32-7 
  XlO" 
  2 
  

  

  1069 
  

  

  218 
  

  

  2924 
  

  

  765 
  

  

  16'6 
  

  

  20-76 
  

  

  682 
  

  

  166 
  

  

  

  645 
  

  

  15-2 
  

  

  19-33 
  

  

  481 
  

  

  14-5 
  

  

  15-27 
  

  

  323 
  

  

  11-2 
  

  

  9-19 
  

  

  251 
  

  

  9-67 
  

  

  

  162 
  

  

  8-95 
  

  

  8-35 
  

  

  79'2 
  

  

  7-68 
  

  

  6-80 
  

  

  40 
  

  

  5-38 
  

  

  531 
  

  

  20-5 
  

  

  3-91 
  

  

  4-03 
  

  

  161 
  

  

  391 
  

  

  

  10-0 
  

  

  2-88 
  

  

  321 
  

  

  80 
  

  

  1-64 
  

  

  

  It 
  is 
  of 
  interest 
  in 
  connexion 
  with 
  these 
  readings 
  to 
  note 
  

   that 
  the 
  conductivity 
  obtained 
  with 
  the 
  negative 
  fields 
  was 
  

   practically 
  the 
  same 
  as 
  that 
  with 
  the 
  positive. 
  This 
  agrees 
  

   with 
  the 
  results 
  obtained 
  by 
  Greinacher 
  in 
  the 
  ionization 
  of 
  

   petrol 
  ether 
  by 
  alpha 
  rays. 
  As 
  pointed 
  out 
  before, 
  Greinacher, 
  

   in 
  the 
  case 
  of 
  his 
  experiments, 
  has 
  drawn 
  the 
  conclusion 
  

   from 
  his 
  results 
  that 
  the 
  positive 
  and 
  negative 
  ions 
  taking 
  

   part 
  in 
  the 
  conductivity 
  impressed 
  upon 
  petrol 
  ether 
  by 
  alpha 
  

   rays 
  have 
  to 
  a 
  very 
  close 
  degree 
  the 
  same 
  mobility. 
  But 
  

   from 
  some 
  experiments 
  to 
  be 
  described 
  later, 
  it 
  will 
  appear 
  

   that 
  this 
  conclusion 
  can 
  scarcely 
  be 
  drawn 
  from 
  the 
  results 
  

   obtained 
  in 
  the 
  liquid 
  air 
  experiments 
  just 
  described. 
  

  

  IV. 
  Ionization 
  in 
  Air 
  at 
  High 
  Pressures 
  by 
  Alpha 
  Rays, 
  

  

  In 
  another 
  set 
  of 
  measurements 
  the 
  system 
  MH, 
  LE, 
  and 
  

   KD 
  with 
  the 
  polonium-coated 
  plate 
  AB 
  in 
  position, 
  fig. 
  3, 
  

   was 
  placed 
  in 
  a 
  receiver 
  with 
  thick 
  steel 
  walls^ 
  and 
  air 
  was 
  

   pumped 
  into 
  it 
  until 
  a 
  pressure 
  of 
  101 
  atmospheres 
  was 
  

   reached. 
  A 
  set 
  of 
  readings 
  similar 
  to 
  those 
  obtained 
  when 
  

   the 
  above 
  s} 
  T 
  stem 
  was 
  immersed 
  in 
  liquid 
  air 
  was 
  then 
  taken, 
  

   but 
  in 
  this 
  case, 
  owing 
  to 
  the 
  much 
  greater 
  conductivity 
  

   which 
  was 
  obtained, 
  a 
  set 
  of 
  sulphur 
  condensers 
  was 
  connected 
  

  

  