﻿106 
  Messrs. 
  A. 
  Holt 
  and 
  E. 
  Hopkinson 
  cm 
  Decomposition 
  

  

  with 
  each 
  experiment, 
  and 
  so 
  presents 
  a 
  larger 
  active 
  surface 
  

   to 
  the 
  electrolytic 
  gas, 
  as 
  it 
  passes 
  over 
  it. 
  

  

  When 
  the 
  bulbs 
  round 
  the 
  electrodes 
  are 
  of 
  large 
  diameter, 
  

   less 
  oxygen 
  and 
  hydrogen 
  is 
  combined 
  by 
  the 
  metallic 
  particles, 
  

   since 
  there 
  is 
  a 
  larger 
  volume 
  of 
  water- 
  vapour 
  into 
  which 
  the 
  

   electrolytic 
  gas 
  produced 
  by 
  the 
  spark 
  can 
  diffuse, 
  and 
  so 
  

   escape 
  the 
  catalytic 
  action. 
  

  

  As 
  the 
  difference 
  between 
  the 
  behaviour 
  of 
  aluminium 
  and 
  

   platinum 
  when 
  used 
  as 
  electrodes 
  during 
  the 
  decomposition 
  

   of 
  water-vapour 
  by 
  electric 
  sparks 
  seemed 
  of 
  considerable 
  

   interest, 
  we 
  were 
  led 
  to 
  examine 
  the 
  action 
  of 
  other 
  metals 
  

   as 
  well. 
  

  

  A 
  number 
  of 
  spark-tubes 
  of 
  the 
  shape 
  shown 
  in 
  fig. 
  4 
  A 
  

   were 
  used, 
  and 
  the 
  pairs 
  of 
  experiments 
  were 
  carried 
  out 
  

   exactly 
  as 
  already 
  described. 
  As 
  it 
  was 
  not 
  possible 
  to 
  obtain 
  all 
  

   the 
  metals 
  in 
  wires 
  of 
  equal 
  thickness, 
  the 
  values 
  for 
  the 
  ratio 
  

   B/A 
  for 
  one 
  metal 
  are 
  not 
  strictly 
  comparable 
  with 
  those 
  for 
  

   another. 
  

  

  The 
  following 
  tables 
  give 
  a 
  summary 
  of 
  the 
  results 
  obtained 
  

   with 
  different 
  metals 
  : 
  — 
  

  

  Electrodes. 
  

  

  Vol. 
  of 
  electrolytic 
  

  

  gas 
  collected 
  in 
  

  

  10 
  mins. 
  when 
  

  

  cathode 
  was 
  at 
  C. 
  

  

  A. 
  

  

  Vol. 
  of 
  electrolytic 
  

   gas 
  collected 
  in 
  

   10 
  mins. 
  when 
  

  

  cathode 
  was 
  at 
  D. 
  

   B. 
  

  

  Ratio 
  

   LA. 
  

  

  Gold 
  

   wire 
  0*5 
  mm. 
  

   diameter. 
  

  

  CroS 
  c.c. 
  

   8-12 
  c.c. 
  

   5-66 
  c.c. 
  

  

  7"79 
  c.c. 
  

   7-32 
  c.c. 
  

   427 
  c.c. 
  

  

  0929 
  

  

  o-uoi 
  

  

  0*764 
  

  

  Silver 
  

   wire 
  1*0 
  ram. 
  

   diameter. 
  

  

  Copper 
  

   wire 
  l'O 
  ram. 
  

   diameter. 
  

  

  841 
  c.c. 
  

   7-94 
  e.o. 
  

   7-84 
  c.c. 
  

  

  8-18 
  c.c. 
  

   7*71 
  c.c. 
  

   761 
  c.c. 
  

  

  0-974 
  

   0971 
  

   970 
  

  

  7-3G 
  c.c. 
  

   824 
  c.c. 
  

  

  7'52 
  o.o. 
  

   6-41 
  0.0. 
  

  

  5' 
  1 
  1 
  c.c. 
  

   6 
  87 
  c.o. 
  

  

  0936 
  

   0-912 
  

  

  10' 
  -.2 
  

  

  1-042 
  

  

  L-008 
  

   1-036 
  

  

  Iron 
  

   wire 
  •'> 
  mm. 
  

   diameter. 
  

  

  509 
  c.c. 
  

   5-22 
  c.c. 
  

  

  Nickel 
  

   w 
  ire 
  <>•;{ 
  mm. 
  

   diameter. 
  

  

  5*83 
  o.c. 
  

   5'76 
  o.c 
  

  

  