﻿96 
  Messrs, 
  A. 
  Holt 
  and 
  E. 
  Hopkinson 
  on 
  Decomposition 
  

  

  of 
  vapour 
  through 
  the 
  two 
  side-tubes 
  G 
  and 
  H, 
  which 
  commu- 
  

   nicated 
  with 
  another 
  condenser 
  also 
  surrounded 
  by 
  a 
  freezing- 
  

   mixture, 
  

  

  Fiff. 
  2. 
  

  

  

  To 
  CONDENSE-R 
  

   AMD 
  PUMT 
  

  

  10 
  CONDENSER 
  

   AND 
  ~Nm? 
  

  

  After 
  condensation 
  of 
  the 
  vapour 
  in 
  the 
  condenser, 
  the 
  

   gases, 
  which 
  consisted 
  of 
  mixtures 
  in 
  different 
  proportions 
  of 
  

   oxygen 
  and 
  hydrogen, 
  were 
  removed 
  by 
  automatic 
  Spreno-el 
  

   pumps, 
  and 
  were 
  collected 
  separately 
  and 
  analysed 
  in 
  the 
  

   same 
  manner 
  as 
  in 
  the 
  experiments 
  of 
  Chapman 
  and 
  Lidbnry. 
  

  

  A 
  voltameter 
  was 
  placed 
  in 
  the 
  circuit 
  so 
  that 
  comparison 
  

   could 
  be 
  made 
  between 
  the 
  amount 
  of 
  decomposition 
  of 
  the 
  

   water- 
  vapour 
  and 
  the 
  quantity 
  of 
  electricity 
  passing 
  in 
  the 
  

   spark. 
  

  

  The 
  rate 
  at 
  which 
  the 
  water-vapour 
  passed 
  through 
  the 
  

   apparatus 
  was 
  varied, 
  and 
  it 
  was 
  noticed 
  that 
  when 
  the 
  current 
  

   of 
  vapour 
  was 
  slow 
  the 
  separation 
  of 
  the 
  oxygen 
  and 
  hydrogen 
  

   was 
  small, 
  but 
  that 
  it 
  increased 
  rapidly 
  as 
  the 
  stream 
  became 
  

   faster, 
  until 
  practically 
  pure 
  hydrogen 
  was 
  collected 
  from 
  the 
  

   diffusion-bulb 
  D. 
  

  

  Ii* 
  the 
  separation 
  of 
  the 
  oxygen 
  and 
  hydrogen 
  is 
  really 
  a 
  

   diffusion 
  phenomenon, 
  one 
  would 
  expect 
  that 
  \\ith 
  this 
  appa- 
  

   ratus 
  the 
  gas 
  collected 
  through 
  E 
  should 
  contain 
  an 
  excess 
  o£ 
  

   hydrogen, 
  while 
  that 
  from 
  (i 
  and 
  11 
  should 
  contain 
  a 
  propor- 
  

   tionate 
  excess 
  of 
  oxygen 
  ; 
  for 
  it 
  [a 
  improbable 
  that 
  any 
  large 
  

   amount, 
  of 
  oxygen 
  could 
  diffuse 
  hack 
  into 
  the 
  bulb 
  1) 
  against 
  

   the 
  rapid 
  current 
  of 
  water-vapour 
  passing 
  from 
  \) 
  to 
  (i 
  and 
  

   pom 
  D'to 
  II. 
  The 
  faster 
  the 
  stream 
  of 
  vapour 
  was 
  passing, 
  

   the 
  less 
  easily 
  could 
  the 
  oxygen 
  diffuse 
  against 
  it, 
  and 
  hence 
  

   the 
  larger 
  the 
  excess 
  of 
  hydrogen 
  found 
  in 
  D. 
  

  

  