﻿of 
  Pressure 
  which 
  accompany 
  Point 
  Discharge. 
  37 
  

  

  this 
  peak 
  which 
  gives 
  the 
  shape 
  Curves 
  V. 
  should 
  take 
  if 
  the 
  

   water-vapour 
  is 
  without 
  effect 
  upon 
  them. 
  (In 
  constructing 
  

   it 
  account 
  was 
  taken 
  of 
  the 
  fact 
  that 
  the 
  scale 
  of 
  minutes 
  is 
  

   not 
  strictly 
  a 
  scale 
  of 
  percentages, 
  and 
  the 
  ordinates 
  were 
  

   reduced 
  to 
  correspond 
  with 
  a 
  current 
  of 
  1*08 
  microamp.) 
  

  

  To 
  distinguish 
  between 
  the 
  tops 
  of 
  c 
  and 
  d 
  their 
  points 
  

   are 
  there 
  joined 
  by 
  straight 
  lines, 
  but 
  everywhere 
  else 
  in 
  

   Curves 
  Y. 
  this 
  constructed 
  curve 
  is 
  drawn 
  so 
  as 
  best 
  to 
  fit 
  

   the 
  points. 
  Near 
  the 
  lower 
  end 
  of 
  the 
  steep 
  part 
  the 
  latter 
  

   are 
  irregular 
  as 
  they 
  are 
  apt 
  to 
  be 
  in 
  that 
  region 
  ; 
  but 
  the 
  

   agreement 
  is 
  in 
  the 
  main 
  good. 
  It 
  shows 
  that 
  Curves 
  V. 
  

   and 
  VIII. 
  are 
  different 
  expressions 
  of 
  practically 
  the 
  same 
  

   phenomenon, 
  though 
  Y. 
  are 
  for 
  wet 
  and 
  YIII. 
  for 
  dry 
  gas. 
  

  

  Now 
  the 
  end 
  of 
  the 
  constructed 
  curve 
  necessarily 
  corre- 
  

   sponds 
  with 
  the 
  absence 
  of 
  any 
  added 
  impurity, 
  and 
  the 
  

   steep 
  part 
  is 
  virtually 
  the 
  end. 
  In 
  Curves 
  Y. 
  c{l,e 
  this 
  part 
  

   is 
  a 
  little 
  to 
  the 
  right 
  of 
  the 
  lower 
  points, 
  suggesting 
  that 
  the 
  

   drop 
  has 
  occurred 
  before 
  the 
  end 
  of 
  the 
  oxygen 
  was 
  reached 
  ; 
  

   but 
  in 
  curve 
  / 
  it 
  is 
  to 
  the 
  left. 
  Even 
  if 
  we 
  regard 
  the 
  

   position 
  of 
  / 
  as 
  due 
  to 
  error, 
  which 
  there 
  is 
  no 
  particular 
  

   reason 
  for 
  doing, 
  the 
  other 
  three 
  curves 
  indicate 
  that 
  not 
  

   more 
  than 
  about 
  10 
  per 
  cent, 
  of 
  the 
  oxygen 
  was 
  left 
  uncom- 
  

   bined 
  at 
  the 
  drop 
  ; 
  and 
  taking 
  / 
  into 
  account 
  makes 
  the 
  

   amount 
  still 
  smaller. 
  

  

  There 
  is 
  a 
  third 
  way 
  in 
  which 
  Curves 
  Y. 
  throw 
  light 
  on 
  

   this 
  matter. 
  It 
  is 
  possible 
  to 
  obtain 
  from 
  them 
  a 
  direct 
  

   comparison 
  of 
  the 
  volume, 
  v 
  , 
  of 
  impurity 
  originally 
  put 
  into 
  

   the 
  discharge 
  vessel 
  with 
  the 
  total 
  contraction, 
  v, 
  measured 
  

   up 
  to 
  the 
  drop. 
  

  

  The 
  results 
  of 
  this 
  comparison 
  for 
  oxygen 
  are 
  given 
  in 
  

   Table 
  2. 
  P 
  is 
  the 
  percentage 
  of 
  oxygen 
  (by 
  volume) 
  

  

  Table 
  2. 
  

  

  4- 
  Discharge. 
  

  

  — 
  Discharge. 
  

  

  P. 
  

  

  v/v 
  . 
  

  

  P. 
  

  

  v/v 
  . 
  

  

  0-00037 
  

   •0010 
  

   •0027 
  

   •0074 
  

  

  I 
  

  

  3-2 
  

   2-8 
  

   2-3 
  

   2-6 
  

  

  27 
  

  

  000016 
  

   •00054 
  

   •0026 
  

   •0035 
  

   •0057 
  

  

  2-7 
  

   32 
  

   2-7 
  

  

  30 
  

  

  2-8 
  

  

  29 
  

  

  