﻿Vapour 
  -Pressures 
  of 
  Carbon 
  Dioxide. 
  153 
  

  

  In 
  our 
  low-temperature 
  determinations 
  never 
  less 
  than 
  

   the 
  "bulb" 
  4- 
  1£ 
  cms. 
  was 
  immersed 
  in 
  the 
  liquid 
  sulphur 
  

   dioxide 
  or 
  ammonia, 
  and 
  the 
  bulb 
  + 
  7 
  cms. 
  was 
  inside 
  the 
  

   Dewar 
  vessel, 
  so 
  that 
  5 
  J 
  cms. 
  of 
  the 
  stem 
  was 
  surrounded 
  by 
  

   the 
  vapour 
  of 
  the 
  boiling 
  liquid. 
  This 
  insufficient 
  immersion 
  

   would 
  account 
  for 
  small 
  irregularities 
  — 
  up 
  to 
  o, 
  05 
  — 
  in 
  our 
  

   readings. 
  

  

  (c) 
  Fixed 
  Points. 
  — 
  The 
  resistance 
  R 
  of 
  the 
  platinum 
  

   spiral 
  at 
  the 
  ice 
  point 
  was 
  found 
  by 
  using 
  a 
  bath 
  of 
  partly 
  

   frozen 
  distilled-water 
  surrounded 
  by 
  an 
  air-jacket 
  on 
  the 
  

   outside 
  of 
  which 
  was 
  a 
  freezing-mixture 
  kept 
  at 
  —3° 
  or 
  —4°. 
  

   The 
  following 
  are 
  some 
  of 
  the 
  readings 
  : 
  — 
  

  

  Values 
  of 
  K 
  . 
  

  

  May 
  10 
  2-8348 
  

  

  June 
  6 
  8 
  

  

  n 
  10 
  7 
  

  

  Mean 
  ...... 
  2*8318 
  ohms. 
  

  

  The 
  steam-point 
  readings 
  were 
  : 
  — 
  

  

  Values 
  of 
  R 
  100 
  . 
  

  

  May 
  10 
  3-8379 
  

  

  78 
  

  

  81 
  

  

  » 
  77 
  

  

  May 
  11 
  76 
  

  

  75 
  

  

  June 
  4 
  • 
  76 
  

  

  >, 
  6 
  76 
  

  

  » 
  10 
  _ 
  77 
  

  

  Mean 
  3*8377 
  ohms. 
  

  

  The 
  platinum 
  temperatures 
  were 
  calculated 
  from 
  the 
  

   formula 
  

  

  pt= 
  *~ 
  R 
  ° 
  x 
  100 
  

  

  -"-100 
  — 
  -""O 
  

  

  and 
  reduced 
  to 
  the 
  air-scale 
  by 
  means 
  of 
  the 
  difference 
  

   formula 
  

  

  5. 
  Ihe 
  Results. 
  — 
  Table 
  I. 
  contains 
  the 
  vapour-pressures 
  of 
  

   carbon 
  dioxide 
  as 
  determined 
  by 
  experiment. 
  

  

  