﻿Positive 
  Electricity. 
  837 
  

  

  carbonic 
  acid, 
  or 
  argon^ 
  were 
  introduced 
  so 
  as 
  to 
  raise 
  the 
  

   pressure 
  sufficiently 
  to 
  produce 
  the 
  discharge, 
  the 
  values 
  of 
  

   ejm 
  and 
  the 
  velocity 
  o£ 
  the 
  particles 
  were 
  the 
  same 
  for 
  all 
  

   gases. 
  Since 
  then 
  1 
  have 
  repeated 
  the 
  experiments 
  and 
  have 
  

   tried 
  in 
  addition 
  to 
  the 
  gases 
  I 
  have 
  mentioned, 
  sulphur 
  

   dioxide, 
  methyl 
  iodide, 
  carbon 
  tetrachloride, 
  and 
  also 
  the 
  

   vapour 
  of 
  a 
  radioactive 
  substance 
  UrCl4. 
  With 
  all 
  these 
  

   gases 
  the 
  values 
  of 
  ejm 
  for 
  the 
  Canalstrahlen 
  were 
  the 
  same 
  

   and 
  equal 
  to 
  10*. 
  This 
  seems 
  strong 
  evidence 
  that 
  there 
  is- 
  

   a 
  definite 
  unit 
  of 
  positive 
  electricity 
  as 
  well 
  as 
  of 
  negative, 
  

   the 
  carrier 
  of 
  the 
  positive 
  unit 
  being 
  much 
  larger 
  than 
  the 
  

   negative. 
  This 
  view 
  seems 
  to 
  me 
  to 
  be 
  very 
  much 
  strength- 
  

   ened 
  by 
  some 
  results 
  recently 
  obtained 
  by 
  Mr. 
  Wellisch 
  at 
  

   the 
  Cavendish 
  Laboratory. 
  The 
  experiments 
  were 
  on 
  the 
  

   mobility 
  of 
  the 
  positive 
  and 
  negative 
  ions 
  in 
  mixtures 
  of 
  

   difEerent 
  gases. 
  If 
  we 
  take 
  the 
  view 
  that 
  the 
  positive 
  ion 
  

   is 
  but 
  the 
  residue 
  left 
  after 
  a 
  corpuscle 
  has 
  been 
  abstracted 
  

   from 
  the 
  molecule, 
  then 
  it 
  would 
  seem 
  probable 
  that 
  in 
  the 
  

   case 
  of 
  positive 
  ions 
  there 
  would, 
  in 
  a 
  mixture 
  of 
  two 
  gases 
  

   A 
  and 
  B, 
  be 
  two 
  different 
  types 
  of 
  positive 
  ions 
  moving 
  with 
  

   different 
  velocities. 
  In 
  one 
  type 
  the 
  positive 
  ion 
  would 
  be 
  

   the 
  molecules 
  of 
  A 
  minus 
  a 
  corpuscle, 
  or 
  an 
  aggregate 
  

   formed 
  round 
  it 
  ; 
  in 
  the 
  other 
  the 
  nucleus 
  would 
  be 
  the 
  

   molecule 
  B. 
  Mr. 
  Wellisch 
  found, 
  however, 
  as 
  M. 
  Blanc 
  

   had 
  previously 
  found 
  for 
  a 
  mixture 
  of 
  air 
  and 
  carbonic 
  acid, 
  

   that 
  in 
  the 
  mixture 
  all 
  the 
  positive 
  ions 
  moved 
  with 
  the 
  same 
  

   velocity. 
  

  

  We 
  might, 
  however, 
  without 
  assuming 
  an 
  independent 
  

   unit 
  of 
  positive 
  electricity, 
  explain 
  this 
  result 
  by 
  supposing 
  

   that 
  the 
  ions 
  were 
  aggregates 
  continually 
  breaking 
  up 
  and 
  

   reforming, 
  and 
  that 
  the 
  velocity 
  measured 
  is 
  the 
  velocity 
  

   of 
  the 
  average 
  aggregate. 
  This 
  explanation 
  is, 
  however, 
  

   refuted 
  by 
  some 
  of 
  the 
  cases 
  examined 
  by 
  Mr. 
  Wellisch. 
  

   The 
  ionization 
  under 
  Rontgen 
  rays 
  of 
  methyl 
  iodide, 
  mercury 
  

   methyl, 
  or 
  carbon 
  tetrachloride, 
  is 
  so 
  vastly 
  greater 
  than 
  

   that 
  of 
  hydrogen, 
  that 
  in 
  mixtures 
  of 
  these 
  gases 
  with 
  

   hydrogen, 
  even 
  when 
  there 
  is 
  only 
  one 
  or 
  two 
  per 
  cent, 
  of 
  

   these 
  gases 
  in 
  the 
  mixture, 
  practically 
  the 
  whole 
  of 
  the 
  

   ionization 
  is 
  due 
  to 
  the 
  methyl 
  iodide. 
  Wellisch 
  found 
  that 
  

   in 
  these 
  mixtures 
  the 
  velocity 
  of 
  the 
  positive 
  ion 
  is 
  nearly 
  

   the 
  same 
  as 
  in 
  pure 
  hydrogen, 
  although 
  practically 
  all 
  the 
  

   ions 
  came 
  from 
  the 
  heavy 
  gases. 
  If 
  the 
  positive 
  ion 
  was 
  

   merely 
  the 
  residue 
  left 
  when 
  the 
  corpuscle 
  was 
  taken 
  out, 
  

   the 
  positive 
  ion 
  would 
  be 
  at 
  least 
  as 
  large 
  as 
  a 
  molecule 
  of 
  

   methyl 
  iodide. 
  We 
  can 
  show, 
  however, 
  that 
  the 
  velocity 
  

   with 
  which 
  the 
  charged 
  molecule 
  would 
  move 
  through 
  the 
  

  

  Phil 
  Mag, 
  S. 
  6. 
  Vol. 
  18. 
  No. 
  108. 
  Dec. 
  1909. 
  3 
  L 
  

  

  