﻿of 
  Water- 
  Vapour 
  by 
  Electric 
  Sparks. 
  

  

  101) 
  

  

  No. 
  of 
  

   Experiment. 
  

  

  Volume 
  of 
  electrolytic 
  

  

  gas 
  collected 
  in 
  

  

  10 
  mins. 
  when 
  cathode 
  

  

  was 
  at 
  C. 
  

  

  Volume 
  of 
  electrolytic 
  

  

  gas 
  collected 
  m 
  

   10 
  mins. 
  when 
  cathode 
  

   was 
  at 
  D. 
  

  

  Ratio 
  

   B/A. 
  

  

  

  A. 
  

  

  B. 
  

  

  

  ~ 
  1. 
  " 
  

  

  6-739 
  c.c. 
  

  

  2-607 
  c.c. 
  

  

  0-386 
  

  

  2. 
  

  

  6293 
  c.c. 
  

  

  0-644 
  c.c. 
  

  

  0-102 
  

  

  3. 
  

  

  6-125 
  c.c. 
  

  

  0-371 
  c.c. 
  

  

  0-060 
  

  

  4. 
  

  

  6-237 
  c.c. 
  

  

  0-317 
  cc. 
  

  

  0051 
  

  

  the 
  oxygen 
  is 
  swept 
  towards 
  the 
  cathode, 
  where 
  it 
  appears 
  

   in 
  excess, 
  while 
  the 
  hydrogen 
  is 
  equally 
  distributed 
  between 
  

   the 
  two 
  poles. 
  A 
  considerable 
  quantity 
  of 
  the 
  electrolytic 
  

   gas 
  passing 
  over 
  the 
  cathode 
  is, 
  however, 
  recombined 
  there, 
  

   so 
  that 
  less 
  oxygen 
  is 
  left 
  to 
  appear 
  in 
  excess 
  at 
  that 
  pole, 
  

   and 
  the 
  hydrogen 
  collected 
  at 
  the 
  anode 
  is 
  proportionately 
  

   diminished. 
  

  

  I£ 
  the 
  point 
  of 
  entry 
  o£ 
  the 
  stream 
  o£ 
  vapour 
  is 
  near 
  the 
  

   cathode, 
  a 
  volume 
  o£ 
  oxygen 
  equal 
  to 
  that 
  which 
  in 
  the 
  

   former 
  case 
  passed 
  over 
  this 
  electrode, 
  and 
  was 
  partially 
  

   recombined, 
  is 
  now 
  driven 
  out 
  at 
  the 
  anode, 
  but 
  its 
  amount 
  is 
  

   not 
  sensibly 
  diminished 
  there, 
  since 
  hardly 
  any 
  recombination 
  

   takes 
  place 
  near 
  this 
  latter 
  pole. 
  

  

  An 
  explanation 
  of 
  the 
  results 
  obtained 
  by 
  Thomson 
  can 
  

   also 
  be 
  given, 
  though 
  the 
  conditions 
  in 
  his 
  experiments 
  and 
  

   in 
  ours 
  were 
  somewhat 
  different, 
  since 
  his 
  steam 
  was 
  at 
  

   atmospheric 
  pressure, 
  whilst 
  our 
  water- 
  vapour 
  was 
  at 
  about 
  

   12 
  mm. 
  pressure, 
  and 
  the 
  amount 
  of 
  metal 
  shot 
  off 
  the 
  cathode, 
  

   and 
  hence 
  the 
  extent 
  of 
  catalysis, 
  increases 
  as 
  the 
  pressure 
  

   decreases. 
  The 
  cathode 
  is 
  surrounded 
  by 
  particles 
  of 
  metal 
  

   w 
  T 
  hich 
  exert 
  a 
  catalytic 
  action 
  on 
  electrolytic 
  gas, 
  so 
  that 
  a 
  

   zone 
  of 
  recombination 
  is 
  found 
  around 
  that 
  pole 
  ; 
  and 
  one 
  of 
  

   us 
  has 
  already 
  pointed 
  out 
  that 
  if 
  a 
  homogeneous 
  mixture 
  of 
  

   oxygen 
  and 
  hydrogen 
  (as 
  is 
  found 
  in 
  the 
  path 
  of 
  the 
  spark) 
  

   is 
  produced 
  inside 
  such 
  a 
  zone, 
  an 
  excess 
  of 
  hydrogen 
  may 
  

   be 
  expected 
  outside 
  it, 
  while 
  the 
  oxygen 
  becomes 
  concentrated 
  

   within 
  (Phil. 
  Mag. 
  1907, 
  vol. 
  xiii. 
  p. 
  630). 
  

  

  If 
  the 
  electrodes 
  are 
  close 
  together, 
  almost 
  the 
  whole 
  spark 
  

   may 
  be 
  inside 
  this 
  recombination 
  zone 
  ; 
  and 
  as, 
  under 
  these 
  

   conditions, 
  the 
  gas 
  swept 
  through 
  the 
  cathode 
  by 
  the 
  water- 
  

   vapour 
  current 
  will 
  chiefly 
  consist 
  of 
  that 
  portion 
  within 
  the 
  

   zone, 
  an 
  excess 
  of 
  oxygen 
  should 
  be 
  found 
  at 
  the 
  cathode, 
  

   and 
  a 
  proportionate 
  excess 
  of 
  hydrogen 
  at 
  the 
  anode. 
  When 
  

   the 
  spark 
  is 
  long, 
  the 
  greater 
  portion 
  of 
  the 
  electrolytic 
  gas 
  

  

  