﻿106 
  II. 
  A 
  . 
  Bumstead 
  — 
  Velocities 
  of 
  Delta 
  Rays. 
  

  

  instead 
  of 
  to 
  kinetic 
  energies, 
  the 
  result 
  is 
  still 
  very 
  far 
  from 
  

   an 
  exponential 
  curve 
  

  

  The 
  form 
  of 
  the 
  curves, 
  however, 
  for 
  both 
  the 
  swifter 
  and 
  

   the 
  slower 
  electrons 
  suggests 
  an 
  equation 
  of 
  the 
  form 
  yx 
  n 
  = 
  C. 
  

   In 
  fact, 
  a 
  very 
  fair 
  agreement 
  between 
  the 
  observations 
  from 
  

   30 
  to 
  500 
  volts, 
  and 
  this 
  equation 
  may 
  be 
  obtained 
  by 
  using 
  

   n 
  — 
  0*75, 
  as 
  may 
  be 
  seen 
  from 
  Table 
  II. 
  In 
  this 
  table 
  the 
  

   observed 
  currents 
  have 
  been 
  increased 
  by 
  12 
  units 
  to 
  allow 
  for 
  

   the 
  ionic 
  current 
  discussed 
  above. 
  

  

  Table 
  II. 
  

  

  yx 
  n 
  

  

  = 
  C 
  

  

  n 
  = 
  

  

  : 
  0-75 
  

  

  x 
  (volts) 
  

  

  y(obs 
  + 
  12) 
  

  

  2/(calc.) 
  

  

  Diff. 
  

  

  20 
  

  

  108' 
  

  

  89' 
  

  

  19- 
  

  

  40 
  

  

  53' 
  . 
  

  

  53' 
  

  

  o- 
  

  

  80 
  

  

  31- 
  

  

  31*2 
  

  

  — 
  0-2 
  

  

  120 
  

  

  23-5 
  

  

  23*2 
  

  

  + 
  0-3 
  

  

  160 
  

  

  19- 
  

  

  18*7 
  

  

  + 
  0-3 
  

  

  200 
  

  

  16-7 
  

  

  15-8 
  

  

  4- 
  0-9 
  

  

  240 
  

  

  14*6 
  

  

  13-8 
  

  

  + 
  0-8 
  

  

  280 
  

  

  11*8 
  

  

  12-3 
  

  

  — 
  0-5 
  

  

  320 
  

  

  11-4 
  

  

  11 
  '1 
  

  

  + 
  0-3 
  

  

  360 
  

  

  105 
  

  

  10*2 
  

  

  + 
  0-3 
  

  

  400 
  

  

  9-5 
  

  

  9-4 
  

  

  + 
  0-1 
  

  

  480 
  

  

  8-5 
  

  

  8'2 
  

  

  + 
  0-3 
  

  

  600 
  

  

  6-2 
  

  

  6-9 
  

  

  - 
  0-7 
  

  

  800 
  

  

  4- 
  

  

  5-6 
  ' 
  

  

  - 
  1*6 
  

  

  ]000 
  

  

  2-6 
  

  

  4-7 
  

  

  — 
  2-1 
  

  

  1200 
  

  

  1-3 
  

  

  41 
  

  

  — 
  2'8 
  

  

  The 
  departure 
  of 
  the 
  observations 
  from 
  the 
  equation 
  at 
  the 
  

   higher 
  voltages 
  may 
  or 
  may 
  not 
  be 
  of 
  significance, 
  since 
  the 
  

   currents 
  under 
  these 
  conditions 
  were 
  small 
  and 
  could 
  not 
  be 
  

   very 
  accurately 
  measured, 
  and 
  the 
  placing 
  of 
  the 
  zero 
  line 
  is 
  

   uncertain. 
  At 
  the 
  lower 
  potentials, 
  however 
  (beginning 
  at 
  20 
  

   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 
  distribution 
  of 
  the 
  slower 
  

   electrons 
  may 
  be 
  obtained 
  with 
  an 
  equation 
  of 
  the 
  same 
  form, 
  

   but 
  with 
  a 
  larger 
  value 
  of 
  n, 
  between 
  1*5 
  and 
  2. 
  

  

  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 
  elec- 
  

   troscope, 
  and 
  introducing 
  a 
  small 
  mica 
  condenser. 
  The 
  results 
  

   were 
  as 
  follows 
  : 
  

  

  