﻿520 
  

  

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

  

  Another 
  interesting 
  question, 
  and 
  one 
  of 
  great 
  importance 
  in 
  reference 
  

   to 
  the 
  laws 
  of 
  molecular 
  action, 
  is 
  the 
  relation 
  between 
  the 
  elastic 
  forces 
  of 
  

   a 
  gas 
  at 
  different 
  temperatures 
  while 
  the 
  volume 
  remains 
  constant. 
  The 
  

   experiments 
  which 
  I 
  hare 
  made 
  in 
  this 
  part 
  of 
  the 
  inquiry 
  are 
  only 
  pre- 
  

   liminary, 
  and 
  were 
  performed 
  not 
  with 
  pure 
  carbonic 
  acid, 
  but 
  with 
  a 
  

   mixture 
  of 
  about 
  11 
  volumes 
  of 
  carbonic 
  acid 
  and 
  1 
  volume 
  of 
  air. 
  It 
  

   will 
  be 
  convenient, 
  for 
  the 
  sake 
  of 
  comparison, 
  to 
  calculate, 
  as 
  is 
  usually 
  

   done, 
  the 
  values 
  of 
  a 
  from 
  these 
  experiments 
  ; 
  but 
  it 
  must 
  be 
  remembered 
  

   that 
  a 
  here 
  represents 
  no 
  longer 
  a 
  coefficient 
  of 
  volume, 
  but 
  a 
  coefficient 
  

   of 
  elastic 
  force. 
  

  

  Elastic 
  force 
  of 
  a 
  mixture 
  of 
  11 
  vol. 
  C0 
  2 
  and 
  1 
  vol. 
  air 
  heated 
  under 
  

   a 
  constant 
  volume 
  to 
  different 
  temperatures. 
  

  

  Yol. 
  C0 
  2 
  . 
  

  

  Temperature. 
  

  

  Elastic 
  Force. 
  

  

  

  

  

  at. 
  

  

  

  366-1 
  

  

  . 
  . 
  13-70 
  

  

  22-90 
  1 
  

  

  

  366-2 
  

  

  40-63 
  

  

  25-74 
  V 
  . 
  

  

  (A) 
  

  

  366-2 
  

  

  99-73 
  

  

  31-65 
  J 
  

  

  

  256-8 
  

  

  13-70* 
  

  

  31-181 
  

  

  

  256-8 
  

  

  40-66 
  

  

  35-44 
  Y 
  • 
  ■ 
  

  

  (8) 
  

  

  256-8 
  

  

  99-75 
  

  

  44-29 
  J 
  

  

  

  From 
  series 
  A 
  we 
  deduce 
  for 
  a 
  unit 
  at 
  13°-70 
  and 
  22*90 
  atmospheres 
  : 
  — 
  

  

  a=0-004604 
  from 
  13°- 
  70 
  to 
  40°-63. 
  

   a=0-004367 
  from 
  40°-63 
  to 
  99°-73. 
  

  

  And 
  from 
  series 
  B 
  : 
  — 
  

  

  a= 
  0-005067 
  from 
  13°-70 
  to 
  40°-66. 
  

   a= 
  0-004804 
  from 
  40°-66 
  to 
  99°-75. 
  

  

  The 
  coefficient 
  at 
  13°- 
  70 
  and 
  1 
  atmosphere 
  is 
  

  

  a 
  = 
  0-003513. 
  

  

  It 
  is 
  clear 
  that 
  the 
  changes 
  in 
  the 
  values 
  of 
  a, 
  calculated 
  from 
  the 
  

   elastic 
  forces 
  under 
  a 
  constaut 
  volume, 
  are 
  in 
  the 
  same 
  direction 
  as 
  

   those 
  already 
  deduced 
  from 
  the 
  expansion 
  of 
  the 
  gas 
  under 
  a 
  constant 
  

   pressure. 
  The 
  value 
  of 
  cc 
  increases 
  with 
  the 
  pressure, 
  and 
  it 
  is 
  greater 
  

   at 
  lower 
  than 
  at 
  higher 
  temperatures. 
  But 
  a 
  remarkable 
  relation 
  exists 
  

   between 
  the 
  coefficients 
  in 
  the 
  present 
  case 
  which 
  does 
  not 
  exist 
  between 
  

   the 
  coefficients 
  obtained 
  from 
  the 
  expansion 
  of 
  the 
  gas. 
  The 
  values 
  of 
  cc, 
  

   deduced 
  for 
  the 
  same 
  range 
  of 
  temperature 
  from 
  the 
  elastic 
  forces 
  at 
  

   different 
  pressures, 
  are 
  directly 
  proportional 
  to 
  one 
  another. 
  We 
  have, 
  

   in 
  short, 
  

  

  0-004367 
  0-04804. 
  

  

  0-004604 
  

  

  :0-9485, 
  

  

  0-05067 
  

  

  :0-9481. 
  

  

  