﻿Velocities 
  of 
  Delta 
  Rays. 
  

  

  249 
  

  

  line 
  is 
  uncertain. 
  At 
  the 
  lower 
  potentials, 
  however 
  (begin- 
  

   ning 
  at 
  -0 
  volts), 
  the 
  equation 
  does 
  not 
  fit 
  at 
  all. 
  This 
  may 
  

   well 
  be 
  due 
  to 
  the 
  large 
  admixture 
  of 
  tertiary 
  electrons 
  at 
  

   these 
  potentials, 
  while 
  above 
  40 
  volts 
  there 
  can 
  be 
  few, 
  if 
  

   any, 
  of 
  these. 
  An 
  approximate 
  representation 
  of 
  the 
  distri- 
  

   bution 
  of 
  the 
  slower 
  electrons 
  may 
  be 
  obtained 
  vftth 
  an 
  

   ecj 
  nation 
  of 
  the 
  same 
  form, 
  but 
  with 
  a 
  larger 
  value 
  of 
  n, 
  

   between 
  1'5 
  and 
  2. 
  

  

  Table 
  II. 
  

  

  *M-» 
  = 
  

  

  C. 
  

  

  n- 
  

  

  = 
  0-75. 
  

  

  x 
  (volts). 
  

  

  ?/(.>b*.4-12). 
  

  

  7/(calc). 
  

  

  Diff. 
  

  

  20 
  

  

  103- 
  

  

  89- 
  

  

  19- 
  

  

  40 
  

  

  53- 
  

  

  53' 
  

  

  ()• 
  

  

  80 
  

  

  31" 
  

  

  31-2 
  

  

  -0-2 
  

  

  120 
  

  

  235 
  

  

  23 
  2 
  

  

  +03 
  

  

  160 
  

  

  ID- 
  

  

  187 
  

  

  + 
  0-3 
  

  

  200 
  

  

  16-7 
  

  

  158 
  

  

  4-09 
  

  

  240 
  

  

  146 
  

  

  13-8 
  

  

  +0-8 
  

  

  280 
  

  

  118 
  

  

  123 
  

  

  -0-5 
  

  

  320 
  

  

  11-4 
  

  

  111 
  

  

  4-0-3 
  

  

  360 
  

  

  105 
  

  

  102 
  

  

  +0-3 
  

  

  400 
  

  

  95 
  

  

  94 
  

  

  +0-1 
  

  

  480 
  

  

  8---» 
  

  

  8-2 
  

  

  +03 
  

  

  600 
  

  

  (52 
  

  

  69 
  

  

  -0-7 
  

  

  800 
  

  

  4- 
  

  

  5-6 
  

  

  -1-6 
  

  

  1000 
  

  

  2-6 
  

  

  47 
  

  

  -21 
  

  

  1200 
  

  

  1-8 
  

  

  41 
  

  

  -2-8 
  

  

  In 
  order 
  to 
  get 
  an 
  idea 
  of 
  the 
  relative 
  magnitudes 
  of 
  the 
  

   currents 
  observed 
  under 
  various 
  conditions, 
  a 
  rough 
  series 
  

   of 
  comparisons 
  was 
  made 
  by 
  altering 
  the 
  sensitiveness 
  of 
  the 
  

   electroscope, 
  and 
  introducing 
  a 
  small 
  mica 
  condenser. 
  The 
  

   results 
  were 
  as 
  follows 
  : 
  — 
  

  

  Electronic 
  

  

  current 
  at 
  —40 
  volts 
  . 
  

  

  . 
  . 
  43 
  

  

  ?> 
  

  

  55 
  

  

  ,,-20 
  

  

  55 
  

  

  . 
  . 
  100 
  

  

  55 
  

  

  55 
  

  

  — 
  2 
  

  

  55 
  

  

  . 
  1700 
  

  

  55 
  

  

  55 
  

  

  „ 
  o 
  

  

  55 
  

  

  . 
  . 
  2700' 
  

  

  95 
  

  

  19 
  

  

  „ 
  +40 
  

  

  55 
  

  

  . 
  5800- 
  

  

  Current 
  carried 
  by 
  

  

  a-rays 
  

  

  

  . 
  200- 
  

  

  Minimum 
  

  

  ionic 
  current 
  

  

  

  . 
  10- 
  

  

  It 
  will 
  be 
  seen 
  that 
  the 
  swifter 
  electrons 
  with 
  which 
  we 
  

   have 
  been 
  principally 
  concerned 
  form 
  only 
  a 
  small 
  part 
  of 
  

   the 
  total 
  number 
  which 
  leave 
  a 
  metal 
  when 
  it 
  is 
  struck 
  by 
  

   a-rays. 
  But 
  the 
  fact 
  that 
  a-rays 
  can 
  cause 
  electrons 
  to 
  be 
  

  

  Phil. 
  May. 
  S. 
  6. 
  Vol. 
  20. 
  No. 
  152. 
  Aug. 
  1913. 
  S 
  

  

  