﻿Ionization 
  of 
  Electrolytic 
  Oxygen. 
  27 
  

  

  By 
  measuring 
  the 
  total 
  charge 
  g 
  in 
  a 
  given 
  volume 
  o£ 
  gas 
  

   and 
  the 
  number 
  n 
  of 
  drops 
  in 
  the 
  cloud 
  he 
  obtained 
  the 
  value 
  

   3 
  X 
  10""^^ 
  for 
  qjn. 
  If 
  all 
  the 
  drops 
  had 
  charges 
  of 
  like 
  sign 
  

   qjn 
  would 
  represent 
  the 
  charge 
  on 
  each 
  ; 
  experiments 
  on 
  the 
  

   conductivity 
  of 
  the 
  charged 
  oxygen 
  from 
  sulphuric 
  acid 
  

   showed 
  that 
  it 
  contained 
  a 
  mixture 
  of 
  positively 
  and 
  nega- 
  

   tively 
  charged 
  particles 
  in 
  the 
  ratio 
  of 
  about 
  4 
  : 
  1, 
  so 
  that 
  the 
  

   charge 
  on 
  each 
  is 
  greater 
  than 
  q/n 
  in 
  the 
  proportion 
  of 
  5 
  : 
  3. 
  

   When 
  this 
  fact 
  is 
  taken 
  into 
  account 
  the 
  value 
  of 
  e 
  would 
  be 
  

   aboi^t 
  5x10-10 
  E.S. 
  units. 
  

  

  At 
  Prof. 
  Townsend's 
  suggestion 
  I 
  have 
  examined 
  the 
  oxygen 
  

   obtained 
  by 
  electrolysis 
  of 
  a 
  solution 
  of 
  potassium 
  hydroxide 
  

   of 
  sp. 
  gr. 
  about 
  1*2, 
  as 
  it 
  appeared 
  probable 
  that 
  an 
  accurate 
  

   value 
  might 
  be 
  obtained 
  by 
  using 
  the 
  method 
  devised 
  by 
  

   Prof. 
  H 
  A. 
  Wilson 
  for 
  measuring 
  the 
  charge 
  on 
  each 
  particle 
  

   in 
  the 
  case 
  of 
  mists 
  produced 
  by 
  adiabatic 
  expansion 
  *. 
  

  

  An 
  electrolvtic 
  foo^ 
  of 
  this 
  nature 
  has 
  two 
  advantao;es 
  over 
  

   an 
  expansion 
  fog 
  which 
  ensure 
  much 
  greater 
  accuracy 
  of 
  

   measurement. 
  The 
  radii 
  of 
  the 
  particles 
  are 
  extremely 
  small, 
  

   and 
  hence 
  their 
  rate 
  of 
  fall 
  is 
  slow 
  (from 
  1 
  to 
  2 
  mm. 
  in 
  a 
  

   minute) 
  and 
  easily 
  observed 
  ; 
  also 
  the 
  cloud 
  is 
  stable, 
  while 
  

   in 
  a 
  fog 
  produced 
  by 
  expansion 
  the 
  velocity 
  is 
  great 
  and 
  it 
  is 
  

   certain 
  that 
  a 
  more 
  or 
  less 
  rapid 
  evaporation 
  must 
  be 
  taking 
  

   place, 
  so 
  that 
  it 
  is 
  impossible 
  to 
  know 
  the 
  size 
  of 
  the 
  drop 
  

   which 
  corresponds 
  to 
  the 
  velocity 
  that 
  is 
  observed. 
  

  

  In 
  my 
  experiments 
  observations 
  on 
  the 
  rate 
  of 
  fall 
  were 
  

   always 
  made 
  over 
  several 
  successive 
  millimetres, 
  and 
  in 
  no 
  

   case 
  was 
  any 
  evidence 
  of 
  a 
  change 
  in 
  the 
  size 
  of 
  the 
  drops 
  

   observable 
  during 
  the 
  course 
  of 
  an 
  experiment. 
  

  

  A 
  current 
  of 
  about 
  10 
  amperes 
  was 
  used 
  for 
  electrolysis 
  

   and 
  electrodes 
  of 
  platinum 
  foil 
  about 
  2*5 
  X 
  3 
  cms. 
  were 
  found 
  

   to 
  give 
  the 
  best 
  results. 
  The 
  oxygen 
  from 
  the 
  anode 
  was 
  

   passed 
  into 
  an 
  apparatus 
  shown 
  in 
  vertical 
  section 
  in 
  the 
  

   figure. 
  

  

  The 
  gas 
  passed 
  up 
  the 
  brass 
  tube 
  a 
  into 
  the 
  observation 
  

   vessel 
  h. 
  This 
  had 
  plane 
  glass 
  slides 
  ; 
  its 
  upper 
  and 
  lower 
  

   boundaries 
  were 
  square 
  brass 
  plates 
  which 
  could 
  be 
  connected 
  

   to 
  the 
  terminals 
  of 
  a 
  battery 
  of 
  secondary 
  cells. 
  The 
  upper 
  

   plate 
  had 
  eight 
  small 
  holes 
  near 
  its 
  edge 
  by 
  which 
  gas 
  might 
  

   escape, 
  and 
  it 
  was 
  suspended 
  from 
  a 
  slightly 
  larger 
  brass 
  plate 
  

   by 
  four 
  bra«s 
  rods. 
  This 
  part 
  of 
  the 
  apparatus 
  was 
  surrounded 
  

   on 
  five 
  sides 
  by 
  a 
  water 
  jacket 
  c 
  having 
  plane 
  gla-^s 
  slides. 
  

   In 
  order 
  to 
  prevent 
  electrolysis 
  in 
  this 
  water 
  it 
  was 
  insulated 
  

   from 
  the 
  base 
  plate 
  by 
  a 
  layer 
  of 
  shellac. 
  

  

  On 
  part 
  of 
  one 
  wall 
  of 
  the 
  chamber 
  h 
  a 
  scale 
  of 
  millimetres 
  

  

  * 
  Phil. 
  Mag. 
  '6] 
  vol. 
  V. 
  1903, 
  p. 
  429. 
  

  

  