﻿766 
  Specific 
  Charge 
  of 
  the 
  Ions 
  emitted 
  by 
  Hot 
  Bodies. 
  

  

  not, 
  for 
  instance 
  : 
  (1) 
  Atoms 
  of 
  the 
  metal. 
  This 
  would 
  

   have 
  involved 
  a 
  great 
  variation 
  in 
  the 
  value 
  of 
  m 
  for 
  the 
  

   above 
  elements 
  whose 
  atomic 
  weights 
  are 
  : 
  carbon 
  12, 
  

   platinum 
  195, 
  and 
  iron 
  56. 
  (2) 
  Atoms 
  or 
  molecules 
  of 
  

   absorbed 
  hydrogen. 
  The 
  value 
  of 
  m/H 
  is 
  far 
  too 
  high 
  for 
  

   this. 
  (3) 
  The 
  positive 
  electrons 
  which 
  Thomson 
  has 
  found 
  

   in 
  the 
  canal 
  rays 
  and 
  which 
  other 
  physicists 
  have 
  suggested 
  

   the 
  a 
  rays 
  might 
  be. 
  These 
  have 
  to 
  be 
  eliminated 
  for 
  the 
  

   same 
  reason 
  as 
  hydrogen. 
  

  

  It 
  has 
  been 
  pointed 
  out 
  that 
  the 
  ions 
  appeared 
  to 
  be 
  quite 
  

   homogeneous, 
  and 
  that 
  the 
  patterns 
  did 
  not 
  show 
  any 
  definite 
  

   broadening 
  out 
  in 
  a 
  magnetic 
  field. 
  These 
  experiments 
  show 
  

   quite 
  definitely, 
  not 
  only 
  that 
  the 
  majority 
  of 
  the 
  ions 
  were 
  

   comparatively 
  heavy, 
  but 
  also 
  that 
  there 
  were 
  no 
  ions 
  (no 
  

   measurable 
  number, 
  that 
  is) 
  which 
  were 
  light 
  enough 
  to 
  fall 
  

   under 
  headings 
  (2) 
  and 
  (3). 
  

  

  The 
  experiments 
  do 
  not 
  seem 
  to 
  indicate 
  that 
  the 
  value 
  of 
  

   e/m 
  depends 
  on 
  the 
  temperature 
  of 
  the 
  hot 
  body 
  in 
  any 
  

   definite 
  way. 
  There 
  was 
  some 
  slight 
  evidence 
  that 
  m 
  tended 
  

   to 
  increase 
  with 
  continued 
  heating 
  of 
  the 
  substance, 
  but 
  this 
  

   point 
  cannot 
  be 
  regarded 
  as 
  definitely 
  established. 
  It 
  is 
  to 
  

   be 
  observed 
  that 
  the 
  stated 
  values 
  of 
  m 
  would 
  be 
  doubled, 
  if 
  

   we 
  were 
  to 
  assume 
  that 
  the 
  positive 
  ions 
  carried 
  twice 
  the 
  

   charge 
  of 
  an 
  electrolytic 
  hydrogen 
  ion, 
  as 
  Townsend 
  * 
  has 
  

   recently 
  found 
  to 
  be 
  the 
  case 
  for 
  the 
  positive 
  ions 
  produced 
  

   by 
  Rontgen 
  rays 
  in 
  air. 
  

  

  The 
  values 
  of 
  wi/H 
  are 
  near 
  to 
  the 
  molecular 
  weights 
  of 
  

   N 
  2 
  , 
  CO, 
  and 
  2 
  , 
  but 
  there 
  appears 
  to 
  be 
  no 
  very 
  convincing 
  

   reason 
  why 
  all 
  the 
  substances 
  investigated 
  should 
  evolve 
  one 
  

   or 
  more 
  of 
  these 
  gases 
  when 
  heated. 
  The 
  current 
  evidence 
  

   indicates 
  that 
  the 
  bulk 
  of 
  the 
  gas 
  given 
  off 
  by 
  metals 
  when 
  

   heated 
  is 
  hydrogen. 
  It 
  is 
  possible 
  that 
  the 
  ions 
  arise 
  from 
  

   some 
  impurity 
  which 
  is 
  common 
  to 
  all 
  the 
  materials 
  which 
  

   have 
  been 
  examined. 
  The 
  most 
  likely 
  one 
  to 
  occur 
  would 
  

   appear 
  to 
  be 
  sodium 
  or 
  its 
  salts, 
  and 
  if 
  positively 
  charged 
  

   sodium 
  atoms 
  were 
  emitted 
  they 
  would 
  furnish 
  a 
  value 
  of 
  

   e/m 
  sufficiently 
  near 
  to 
  that 
  which 
  has 
  been 
  observed. 
  

  

  There 
  does 
  not 
  appear 
  to 
  be 
  any 
  evidence 
  of 
  the 
  occurrence 
  

   of 
  light 
  positive 
  ions, 
  even 
  after 
  the 
  metal 
  has 
  been 
  heated 
  

   for 
  a 
  long 
  time, 
  so 
  that 
  the 
  greater 
  part 
  of 
  the 
  initial 
  positive 
  

   ionization 
  has 
  been 
  got 
  rid 
  of. 
  The 
  absence 
  of 
  ions 
  of 
  this 
  

   kind 
  is 
  consistent 
  with 
  the 
  view 
  which 
  the 
  author 
  f 
  has 
  pre- 
  

   viously 
  expressed 
  that 
  the 
  positive 
  ions 
  produced 
  by 
  hot 
  

  

  * 
  Roy. 
  Soc. 
  Proc. 
  A, 
  vol. 
  lxxx. 
  p. 
  207 
  (1908). 
  

   t 
  Phil. 
  Trans. 
  A. 
  vol. 
  ccvii. 
  p. 
  1 
  (1906). 
  

  

  