﻿516 
  

  

  Dr. 
  Andrews 
  on 
  the 
  Phijsical 
  Properties 
  of 
  [June 
  17, 
  

  

  carbonic 
  acid, 
  indeed, 
  that 
  I 
  have 
  hitherto 
  chiefly 
  worked, 
  as 
  it 
  is 
  sin- 
  

   gularly 
  well 
  adapted 
  for 
  experiment 
  ; 
  and 
  the 
  properties 
  it 
  exhibits 
  will 
  

   doubtless, 
  in 
  their 
  main 
  features, 
  be 
  found 
  to 
  represent 
  those 
  of 
  other 
  

   gaseous 
  bodies 
  at 
  corresponding 
  temperatures 
  below 
  and 
  above 
  their 
  

   critical 
  points. 
  

  

  Liquefaction 
  of 
  Carbonic 
  Acid 
  Gas. 
  — 
  The 
  following 
  results 
  have 
  been 
  

   obtained 
  from 
  a 
  number 
  of 
  very 
  careful 
  experiments, 
  and 
  give, 
  it 
  is 
  

   believed, 
  the 
  pressures, 
  as 
  measured 
  by 
  an 
  air-manometer, 
  at 
  which 
  

   carbonic 
  acid 
  liquefies 
  for 
  the 
  temperatures 
  stated 
  : 
  — 
  

  

  Temperatures 
  in 
  Pressure 
  in 
  

  

  Centigrade 
  degrees. 
  atmospheres. 
  

  

  . 
  35-04 
  

  

  5-45 
  40-44 
  

  

  11-45 
  47-04 
  

  

  16-92 
  53-77 
  

  

  22-22 
  61-13 
  

  

  25-39 
  65*78 
  

  

  28-30 
  70-39 
  

  

  I 
  have 
  been 
  gratified 
  to 
  find 
  that 
  the 
  two 
  results 
  (for 
  13 
  o, 
  09 
  and 
  

   21°-46) 
  recorded 
  in 
  my 
  former 
  paper 
  are 
  in 
  close 
  agreement 
  with 
  these 
  

   later 
  experiments. 
  On 
  the 
  other 
  hand, 
  the 
  pressures 
  I 
  have 
  found 
  are 
  

   lower 
  than 
  those 
  given 
  by 
  Kegnault 
  as 
  the 
  result 
  of 
  his 
  elaborate 
  investi- 
  

   gation 
  (Memoires 
  de 
  l'Academie 
  des 
  Sciences, 
  vol. 
  xxvi. 
  p. 
  618). 
  The 
  

   method 
  employed 
  by 
  that 
  distinguished 
  physicist 
  was 
  not, 
  however, 
  fitted 
  

   to 
  give 
  accurately 
  the 
  pressures 
  at 
  which 
  carbonic 
  acid 
  gas 
  liquefies. 
  It 
  

   gave, 
  indeed, 
  the 
  pressures 
  exercised 
  by 
  the 
  liquid 
  when 
  contained 
  in 
  large 
  

   quantity 
  in 
  a 
  Thilorier's 
  reservoir 
  ; 
  but 
  these 
  pressures 
  are 
  always 
  con- 
  

   siderably 
  in 
  excess 
  of 
  the 
  true 
  pressures 
  in 
  consequence 
  of 
  the 
  unavoid- 
  

   able 
  presence 
  of 
  a 
  small 
  quantity 
  of 
  compressed 
  air, 
  although 
  the 
  greatest 
  

   precautions 
  may 
  have 
  been 
  taken 
  in 
  filling 
  the 
  apparatus. 
  Even 
  part 
  

   of 
  air 
  will 
  exercise 
  a 
  serious 
  disturbing 
  influence 
  when 
  the 
  reservoir 
  

   contains 
  a 
  notable 
  quantity 
  of 
  liquid. 
  

  

  Law 
  of 
  Boyle. 
  — 
  The 
  large 
  deviations 
  in 
  the 
  case 
  of 
  carbonic 
  acid 
  at 
  

   high 
  pressures 
  from 
  this 
  law 
  appeared 
  distinctly 
  from 
  several 
  of 
  the 
  

   results 
  given 
  in 
  my 
  former 
  paper. 
  I 
  have 
  now 
  finished 
  a 
  long 
  series 
  of 
  

   experiments 
  on 
  its 
  compressibility 
  at 
  the 
  respective 
  temperatures 
  of 
  

   6°-7, 
  63°-7, 
  and 
  100° 
  Centigrade. 
  The 
  two 
  latter 
  temperatures 
  were 
  

   obtained 
  by 
  passing 
  the 
  vapours 
  of 
  pyroxylic 
  spirit 
  (methyl 
  alcohol) 
  

   and 
  of 
  water 
  into 
  the 
  rectangular 
  case 
  with 
  plate-glass 
  sides 
  in 
  which 
  

   the 
  tube 
  containing 
  the 
  carbonic 
  acid 
  is 
  placed. 
  The 
  temperature 
  of 
  the 
  

   vapour 
  of 
  the 
  pyroxylic 
  spirit 
  was 
  observed 
  by 
  an 
  accurate 
  thermo- 
  

   meter, 
  whose 
  indications 
  were 
  corrected 
  for 
  the 
  unequal 
  expansion 
  of 
  the 
  

   mercury 
  ; 
  while 
  that 
  of 
  the 
  vapour 
  of 
  water 
  was 
  deduced 
  from 
  the 
  

   pressure 
  as 
  given 
  by 
  the 
  height 
  of 
  the 
  barometer 
  and 
  a 
  water-gauge 
  

   attached 
  to 
  the 
  apparatus. 
  At 
  the 
  lower 
  temperature 
  (6°-7) 
  the 
  range 
  

   of 
  pressure 
  which 
  could 
  be 
  applied 
  was 
  limited 
  by 
  the 
  occurrence 
  of 
  

  

  