﻿sions 
  per 
  

  

  rainute, 
  

  

  n 
  >? 
  

  

  55 
  

  

  55 
  91 
  

  

  55 
  

  

  55 
  55 
  

  

  55 
  

  

  Velocities 
  of 
  Delta 
  Rays, 
  '2 
  l?> 
  

  

  was 
  increased 
  to 
  9 
  amperes. 
  It 
  was 
  independent 
  of 
  the 
  

   potential 
  applied 
  to 
  the 
  gauze 
  from 
  —40 
  volts 
  to 
  —1200, 
  

   but 
  it 
  did 
  varv 
  with 
  the 
  time 
  after 
  the 
  vacuum 
  was 
  made 
  in 
  

   the 
  same 
  manner 
  as 
  the 
  results 
  obtained 
  previously. 
  For 
  

   example, 
  with 
  —40 
  volts 
  on 
  the 
  gauze,, 
  and 
  a 
  magnetic 
  field 
  

   o£ 
  250 
  units, 
  the 
  Hollowing 
  values 
  of 
  the 
  current 
  were 
  ob- 
  

   tained 
  at 
  different 
  times 
  after 
  the 
  application 
  of 
  the 
  liquid 
  

   air 
  to 
  the 
  charcoal 
  :— 
  

  

  1 
  hour 
  .... 
  126 
  

  

  3 
  hours 
  .... 
  72 
  

   24 
  „ 
  .... 
  25 
  

   48 
  „ 
  .... 
  12 
  

  

  "We 
  are, 
  I 
  think, 
  justified 
  in 
  concluding 
  that 
  the 
  carriers 
  

   of 
  this 
  current 
  are 
  not 
  electrons, 
  but 
  ions 
  of 
  atomic 
  mass. 
  

   Thus, 
  in 
  a 
  magnetic 
  field 
  of 
  2o0 
  gausses, 
  an 
  electron 
  whose 
  

   velocity 
  was 
  as 
  great 
  as 
  that 
  corresponding 
  to 
  1G00 
  volts 
  

   would 
  be 
  curled 
  into 
  a 
  circle 
  of 
  only 
  half 
  a 
  centimetre 
  radius, 
  

   and 
  could 
  scarcely 
  reach 
  the 
  electrode, 
  even 
  if 
  it 
  started 
  

   from 
  the 
  case 
  with 
  that 
  velocity 
  ; 
  and 
  there 
  is 
  no 
  evidence 
  

   that 
  any 
  swift 
  electrons 
  start 
  from 
  the 
  case 
  at 
  all. 
  On 
  the 
  

   other 
  hand, 
  a 
  hydrogen 
  ion 
  whose 
  velocity 
  was 
  due 
  to 
  a 
  fall 
  

   of 
  potential 
  of 
  only 
  9 
  volts 
  would 
  move 
  in 
  a 
  path 
  whose 
  

   radius 
  of 
  curvature 
  is 
  1'7 
  cm., 
  and 
  might 
  escape 
  from 
  the 
  

   electrode, 
  while 
  an 
  oxygen 
  atom 
  with 
  a 
  single 
  charge 
  

   certainly 
  would, 
  as 
  its 
  radius 
  of 
  curvature 
  would 
  be 
  6*7 
  cm. 
  

  

  Assuming 
  then, 
  that 
  the 
  negative 
  current 
  is 
  carried 
  bv 
  

   such 
  positive 
  ions 
  from 
  the 
  gas 
  film 
  upon 
  the 
  source, 
  it 
  

   is 
  nnnecessary 
  to 
  suppose 
  that 
  they 
  are 
  emitted 
  with 
  an 
  

   appreciable 
  velocity, 
  as 
  any 
  of 
  the 
  electric 
  fields 
  used 
  in 
  the 
  

   preceding 
  experiments 
  would 
  be 
  sufficient 
  to 
  take 
  them 
  

   through 
  the 
  magnetic 
  field. 
  It 
  seems 
  more 
  probable 
  that 
  it 
  

   i- 
  -imply 
  an 
  ionization 
  of 
  the 
  gas 
  film 
  by 
  the 
  a-rays. 
  When 
  

   the 
  current 
  in 
  question 
  is 
  reduced 
  to 
  its 
  minimum 
  value 
  by 
  

   three 
  or 
  four 
  days 
  duration 
  of 
  the 
  vacuum, 
  the 
  charge 
  carried 
  

   by 
  it 
  is 
  from 
  5 
  to 
  10 
  per 
  cent, 
  of 
  that 
  carried 
  by 
  all 
  the 
  

   a-ravs 
  from 
  the 
  polonium 
  (see 
  § 
  6). 
  If 
  the 
  ions 
  have 
  losl 
  a 
  

   single 
  electronic 
  charge, 
  this 
  means 
  that 
  only 
  one 
  out 
  of 
  ten 
  

   (or 
  one 
  out 
  of 
  five) 
  of 
  the 
  a-particles, 
  in 
  its 
  passage 
  through 
  

   the 
  surface 
  film, 
  produces 
  a 
  positive 
  ion 
  which 
  can 
  gel 
  away. 
  

   A\ 
  hen 
  the 
  surface 
  film 
  is 
  not 
  so 
  much 
  reduced 
  by 
  long 
  

   exposure 
  to 
  a 
  high 
  vacuum, 
  this 
  number 
  is 
  considerably 
  

   er. 
  

  

  It. 
  is 
  possible 
  that 
  negative 
  ions 
  of 
  atomic 
  size 
  may 
  also 
  be 
  

   produced, 
  but 
  the 
  present 
  apparatus 
  is 
  not 
  adapted 
  to 
  decide 
  

  

  