﻿of 
  Pressure 
  which 
  accompany 
  Point 
  Discharge. 
  35 
  

  

  p. 
  37, 
  and 
  are 
  so 
  nearly 
  coincident 
  with 
  the 
  points 
  that 
  it 
  

  

  did 
  not 
  seem 
  necessary 
  to 
  complicate 
  the 
  figure 
  with 
  a 
  

  

  second 
  set. 
  

  

  Curves 
  V. 
  — 
  Air 
  in 
  Hydrogen. 
  

  

  Dyne-cm.' 
  

  

  a 
  o«0023 
  

  

  30 
  Minutes 
  

  

  The 
  question 
  whether 
  this 
  sudden 
  drop 
  in 
  the 
  contraction 
  

   curve 
  means 
  that 
  the 
  whole 
  of 
  the 
  oxygen 
  has 
  been 
  trans- 
  

   formed 
  into 
  water-vapour 
  naturally 
  arises 
  here. 
  We 
  have 
  not 
  

   yet 
  had 
  the 
  opportunity 
  of 
  obtaining 
  the 
  data 
  necessary 
  for 
  a 
  

   complete 
  answer, 
  as 
  it 
  involves 
  greater 
  modification 
  of 
  the 
  

   apparatus 
  than 
  we 
  are 
  at 
  present 
  in 
  a 
  position 
  to 
  carry 
  out, 
  

   but 
  the 
  following 
  arguments 
  show 
  that 
  the 
  quantity 
  of 
  un- 
  

   combined 
  oxygen 
  present 
  when 
  the 
  drop 
  is 
  reached 
  is 
  at 
  most 
  

   10 
  per 
  cent, 
  of 
  what 
  was 
  originally 
  mixed 
  with 
  the 
  hydrogen, 
  

   and 
  probably 
  less. 
  

  

  There 
  is 
  nothing 
  a 
  priori 
  impossible 
  in 
  the 
  idea 
  that 
  

   practically 
  the 
  whole 
  of 
  the 
  oxygen 
  may 
  enter 
  into 
  com- 
  

   bination 
  with 
  the 
  hydrogen, 
  for 
  Sernst 
  * 
  has 
  shown 
  that 
  the 
  

   equilibrium 
  pressure 
  of 
  oxygen 
  in 
  a 
  mixture 
  of 
  that 
  gas 
  with 
  

   hydrogen 
  and 
  water-vapour 
  is 
  vanishingly 
  small 
  at 
  ordinary 
  

   temperatures. 
  At 
  the 
  same 
  time 
  an 
  agent 
  like 
  discharge 
  does 
  

   not 
  necessarily 
  result 
  in 
  the 
  same 
  equilibrium 
  pressures 
  as 
  

   heat. 
  Collie 
  j 
  has 
  obtained 
  measurements 
  of 
  true 
  equilibrium 
  

   pressures 
  in 
  the 
  case 
  of 
  CO, 
  3 
  , 
  and 
  C0 
  2 
  which 
  are 
  quite 
  

   different 
  to 
  the 
  values 
  given 
  by 
  Nernst 
  for 
  these 
  substances. 
  

   Collie 
  worked 
  at 
  pressures 
  of 
  a 
  few 
  millimetres, 
  and 
  found 
  

   that 
  about 
  70 
  per 
  cent, 
  of 
  his 
  C0 
  2 
  had 
  been 
  dissociated 
  on 
  

   reaching 
  the 
  equilibrium 
  point. 
  Also 
  Noda 
  and 
  Warburg_f 
  , 
  

  

  * 
  Nernst, 
  Zeit. 
  Phys. 
  Chem. 
  lvi. 
  p. 
  534. 
  

   t 
  Collie, 
  Journ. 
  Chem. 
  Soc. 
  1901, 
  p. 
  1063. 
  

   X 
  Noda 
  & 
  Warburg, 
  Drude's 
  Annalen, 
  xix. 
  p. 
  1. 
  

   D2 
  

  

  