﻿the 
  Porous 
  Plug 
  Experiment, 
  

  

  165 
  

  

  the 
  same 
  ordinate 
  during 
  the 
  escape 
  o£ 
  the 
  gas 
  gives 
  the 
  

   reduction 
  in 
  temperature 
  caused 
  by 
  the 
  escape, 
  and 
  this 
  

  

  Fio;. 
  2, 
  

  

  (1) 
  Witliout 
  escape 
  of 
  gas. 
  

  

  (2) 
  With 
  escape 
  of 
  gas. 
  

  

  multiplied 
  by 
  the 
  water 
  equivalent 
  of 
  the 
  apparatus 
  gives 
  the 
  

   heat 
  absorbed 
  in 
  the 
  process. 
  

  

  In 
  this 
  particular 
  case 
  the 
  cooling 
  amounted 
  to 
  0''*926 
  C, 
  

   and 
  the 
  heat 
  absorbed 
  in 
  the 
  process 
  to 
  215 
  units 
  nearly. 
  

   Since 
  the 
  gas 
  during 
  escape 
  was 
  at 
  an 
  average 
  temperature 
  

   o£ 
  37° 
  C. 
  it 
  was 
  above 
  the 
  critical 
  temperature, 
  and 
  the 
  

   pressure 
  w^as 
  calculated 
  by 
  finding 
  the 
  volume 
  occupied 
  by 
  

   the 
  gas, 
  and 
  dividing 
  this 
  by 
  the 
  capacity 
  of 
  the 
  bulb. 
  

  

  The 
  volume 
  of 
  the 
  gas 
  at 
  37° 
  C. 
  and 
  760 
  mm. 
  was 
  

  

  4-56x22320x310 
  

   44x273 
  

  

  = 
  2630 
  cc. 
  

  

  and 
  since 
  the 
  capacity 
  of 
  the 
  bulb 
  was 
  5'35 
  cc. 
  the 
  pressure 
  

   was 
  

  

  -^-^^^ 
  =492 
  atmospheres. 
  

  

  Amagat's 
  curves 
  show 
  that 
  at 
  this 
  high 
  pressure 
  Boyle's 
  law 
  

   holds 
  for 
  carbonic 
  acid. 
  

  

  As 
  the 
  gas 
  escaped 
  the 
  pressure 
  fell, 
  and 
  it 
  was 
  assumed 
  

  

  