﻿of 
  Pressure 
  which 
  accompany 
  Point 
  Discharge. 
  47 
  

  

  make 
  it 
  likely 
  that 
  some 
  part 
  of 
  the 
  effect 
  of 
  oxygen 
  on 
  the 
  

   conductivity 
  is 
  due 
  to 
  an 
  increase 
  in 
  the 
  sizes 
  of 
  the 
  ions, 
  

   as 
  Warburg 
  himself 
  thought 
  possible. 
  It 
  will 
  be 
  interesting 
  

   to 
  test 
  this 
  by 
  direct 
  measurement 
  of 
  the 
  ionic 
  velocities; 
  

   our 
  new 
  apparatus 
  will 
  we 
  hope 
  enable 
  us 
  to 
  do 
  so. 
  

  

  Summary 
  of 
  Results. 
  

  

  1. 
  Oxygen 
  present 
  in 
  hydrogen 
  at 
  atmospheric 
  pressure 
  

   and 
  subjected 
  to 
  point 
  discharge, 
  combines 
  with 
  the 
  hydrogen 
  

   at 
  the 
  rate 
  of 
  about 
  16 
  molecules 
  of 
  oxygen 
  per 
  ion 
  for 
  

   positive 
  and 
  25 
  molecules 
  for 
  negative 
  between 
  the 
  per- 
  

   centages 
  2 
  and 
  14 
  by 
  volume 
  for 
  the 
  particular 
  point 
  used. 
  

  

  2. 
  Below 
  2 
  per 
  cent, 
  the 
  combination 
  for 
  negative 
  rises 
  

   rapidly 
  until 
  it 
  may 
  reach 
  as 
  many 
  as 
  1 
  10 
  molecules 
  per 
  ion 
  

   below 
  O'Ol 
  per 
  cent. 
  

  

  3. 
  Below 
  0*2 
  per 
  cent, 
  of 
  oxygen 
  the 
  combination 
  for 
  

   positive 
  is 
  about 
  constant, 
  and 
  roughly 
  equal 
  to 
  10 
  molecules 
  

   per 
  ion. 
  

  

  4. 
  There 
  is 
  evidence 
  that 
  at 
  least 
  90 
  per 
  cent, 
  of 
  the 
  oxygen 
  

   can 
  be 
  caused 
  to 
  combine 
  with 
  the 
  hydrogen 
  by 
  point 
  dis- 
  

   charge. 
  

  

  5. 
  The 
  presence 
  of 
  one 
  part 
  of 
  oxygen 
  and 
  upwards 
  in 
  ten 
  

   million 
  of 
  hydrogen 
  can 
  be 
  detected 
  and 
  roughly 
  measured 
  

   by 
  the 
  methods 
  here 
  described. 
  

  

  6. 
  The 
  maximum 
  contraction 
  producible 
  is 
  about 
  2'8 
  times 
  

   greater 
  than 
  the 
  volume 
  of 
  the 
  oxygen 
  present 
  when 
  the 
  

   water- 
  vapour 
  is 
  allowed 
  to 
  remain 
  in 
  the 
  discharge 
  vessel. 
  

  

  7. 
  When 
  nitrogen 
  is 
  present 
  with 
  oxygen 
  in 
  hydrogen, 
  

   even 
  in 
  enormous 
  excess, 
  the 
  combination 
  that 
  occurs 
  is 
  

   mainly, 
  and 
  perhaps 
  wholly, 
  between 
  the 
  oxygen 
  and 
  the 
  

   hydrogen. 
  

  

  8. 
  About 
  7 
  per 
  cent, 
  of 
  the 
  contraction 
  occurs 
  after 
  the 
  

   discharge 
  has 
  ceased. 
  

  

  9. 
  There 
  is 
  evidence 
  which 
  suggests 
  that 
  the 
  addition 
  of 
  

   oxygen 
  above 
  # 
  01 
  per 
  cent, 
  increases 
  the 
  size 
  of 
  the 
  negative 
  

   ions 
  ; 
  while 
  its 
  effect 
  on 
  the 
  positive 
  ions 
  is 
  inappreciable. 
  

  

  10. 
  In 
  pure 
  hydrogen 
  the 
  contraction 
  corresponds 
  to 
  about 
  

   1 
  molecule 
  per 
  ion. 
  

  

  