﻿828 
  Sir 
  J. 
  J. 
  Thomson 
  on 
  

  

  with 
  a 
  constant 
  magnetic 
  field 
  the 
  negative 
  rays 
  are 
  much 
  

   brighter 
  when 
  the 
  magnetic 
  force 
  is 
  at 
  some 
  distance 
  away 
  

   from 
  the 
  cathode 
  and 
  towards 
  the 
  screen 
  than 
  when 
  it 
  i» 
  

   applied 
  nearer 
  to 
  the 
  cathode. 
  

  

  The 
  action 
  o£ 
  the 
  magnetic 
  field 
  in 
  increasing 
  the 
  number 
  

   of 
  these 
  negatively 
  electrified 
  particles 
  is 
  easily 
  understood^ 
  

   lor 
  in 
  a 
  strong 
  field 
  the 
  negative 
  corpuscles 
  can 
  only 
  move 
  

   along 
  the 
  lines 
  of 
  force 
  and 
  thus 
  get 
  concentrated 
  into 
  a 
  

   cloud 
  ; 
  an 
  unelectrified 
  doublet 
  passing 
  through 
  this 
  would 
  

   be 
  very 
  liable 
  to 
  get 
  electrified. 
  

  

  There 
  is 
  in 
  general 
  an 
  abrupt 
  falling 
  off 
  in 
  the 
  intensity 
  of 
  

   the 
  luminosity 
  under 
  electric 
  and 
  magnetic 
  forces 
  as 
  we 
  pass 
  

   from 
  the 
  position 
  of 
  the 
  spot 
  corresponding 
  to 
  uncharged 
  rays 
  

   into 
  the 
  position 
  corresponding 
  to 
  negatively 
  charged 
  rays. 
  

   This 
  shows 
  that 
  the 
  uncharged 
  rays 
  are 
  not 
  rays 
  which 
  start 
  by 
  

   being 
  positively 
  electrified, 
  then 
  take 
  up 
  a 
  corpuscle 
  and 
  get 
  

   neutralized, 
  then 
  another 
  corpuscle 
  and 
  become 
  negatively 
  

   electrified, 
  then 
  lose 
  a 
  corpuscle 
  and 
  so 
  on, 
  repeating 
  this 
  

   process 
  so 
  that 
  on 
  the 
  average 
  the 
  charge 
  is 
  as 
  often 
  positive 
  

   as 
  negative 
  ; 
  for 
  if 
  this 
  were 
  the 
  case, 
  the 
  number 
  of 
  these 
  

   would 
  be 
  very 
  nearly 
  the 
  same 
  as 
  that 
  of 
  those 
  which 
  had 
  

   slightly 
  overshot 
  the 
  mark 
  and 
  become 
  on 
  the 
  average 
  just 
  a 
  

   little 
  more 
  negative 
  than 
  positive, 
  and 
  these 
  would 
  be 
  found 
  

   amongst 
  the 
  negative 
  rays, 
  and 
  the 
  transition 
  from 
  the 
  one 
  

   to 
  the 
  other 
  would 
  be 
  gradual. 
  

  

  Everything 
  points, 
  i 
  think, 
  to 
  the 
  conclusion 
  that 
  even 
  at 
  

   the 
  start 
  from 
  the 
  cathode 
  the 
  Canalstrahlen 
  include 
  a 
  large 
  

   number 
  of 
  neutral 
  doublets, 
  if 
  indeed 
  they 
  do 
  not 
  wholly 
  

   consist 
  of 
  them. 
  

  

  These 
  neutral 
  doublets 
  are 
  found 
  not 
  only 
  in 
  Canalstrahlen, 
  

   the 
  rays 
  at 
  the 
  back 
  of 
  the 
  cathode 
  which 
  have 
  passed 
  through 
  

   it, 
  they 
  are 
  also 
  found 
  in 
  front 
  of 
  the 
  cathode 
  travelling 
  away 
  

   from 
  it, 
  mixed 
  up 
  with 
  rays 
  which 
  carry 
  a 
  positive 
  charge 
  of 
  

   electricity 
  and 
  which 
  are 
  thus 
  travelling 
  against 
  the 
  electric 
  

   field. 
  

  

  The 
  values 
  of 
  e/m 
  for 
  these 
  positively 
  charged 
  rays 
  in 
  front 
  

   of 
  the 
  cathode 
  are, 
  as 
  I 
  have 
  shown 
  (see 
  Phil. 
  Mag. 
  Oct. 
  1908), 
  

   the 
  same 
  as 
  for 
  the 
  Canalstrahlen 
  ; 
  it 
  is 
  convenient 
  to 
  call 
  

   the 
  positively 
  charged 
  rays 
  which 
  travel 
  away 
  from 
  the 
  

   cathode 
  in 
  the 
  same 
  direction 
  as 
  the 
  cathode 
  rays, 
  " 
  Retro- 
  

   grade 
  rays.'"* 
  The 
  presence 
  of 
  neutral 
  doublets 
  is 
  even 
  more 
  

   marked 
  among 
  the 
  retrograde 
  rays 
  than 
  among 
  the 
  Canal- 
  

   strahlen. 
  

  

  These 
  neutral 
  doublets 
  are 
  very 
  interesting, 
  as 
  they 
  form 
  

   an 
  intermediate 
  stage 
  between 
  the 
  ion 
  and 
  the 
  neutral 
  

   molecule. 
  They 
  are 
  found 
  not 
  only 
  in 
  these 
  high 
  tension 
  

  

  