﻿the 
  Porous 
  Plug 
  Experiment. 
  

   Table 
  I. 
  

  

  163 
  

  

  

  

  ^ 
  

  

  

  t3 
  

  

  

  

  

  t 
  

  

  

  Z 
  . 
  

  

  ^• 
  

  

  J 
  

  

  

  

  ^ 
  2 
  

  

  Teiuperatu 
  

  

  Weight 
  of 
  

   gas. 
  

  

  1— 
  1 
  

  

  1-5 
  

  

  Heat 
  absoi 
  

   by 
  plug 
  

  

  

  t 
  

  

  ^1 
  

  

  18-5 
  

  

  4-8 
  

  

  283-5 
  

  

  182-4 
  

  

  102-6 
  

  

  102 
  

  

  54-2 
  

  

  1-8 
  

  

  21-3 
  

  

  4-4 
  

  

  262 
  

  

  159-6 
  

  

  102-6 
  

  

  112 
  

  

  57-9 
  

  

  1-93 
  

  

  21-85 
  

  

  4-39 
  

  

  260 
  

  

  146 
  

  

  114 
  

  

  123 
  

  

  58-9 
  

  

  2-08 
  

  

  23 
  

  

  4-4 
  

  

  244 
  

  

  140 
  

  

  104 
  

  

  112 
  

  

  60-4 
  

  

  1-84 
  

  

  23-3 
  

  

  3-68 
  

  

  200 
  

  

  114 
  

  

  86 
  

  

  111 
  

  

  60-9 
  

  

  1-82 
  

  

  The 
  latent 
  heat 
  o£ 
  the 
  whole 
  mass 
  of 
  the 
  oas 
  was 
  calculated 
  

  

  by 
  the 
  usual 
  formula 
  

  

  fT(y,-y), 
  

   dh 
  

  

  the 
  values 
  oE 
  Y, 
  Vi, 
  and 
  -3- 
  being 
  taken 
  from 
  Amagat's 
  

  

  table*, 
  — 
  the 
  values 
  of 
  the 
  pressures 
  "svere 
  also 
  taken 
  from 
  the 
  

   same 
  source. 
  

  

  It 
  may 
  be 
  objected 
  that 
  the 
  pressure 
  varied 
  during 
  the 
  

   experiment, 
  and 
  this 
  of 
  course 
  is 
  true 
  ; 
  but 
  dealing 
  with 
  such 
  

   small 
  amounts 
  of 
  liquid 
  gas, 
  it 
  would 
  be 
  extremely 
  difficult 
  

   to 
  measure 
  the 
  alterations 
  in 
  pressure 
  occurring 
  during 
  an 
  

   ■experiment. 
  If, 
  however, 
  we 
  assume 
  that 
  the 
  gas 
  is 
  boiling 
  

   steadily, 
  as 
  is 
  probably 
  the 
  case, 
  the 
  pressure 
  inside 
  the 
  bulb 
  

   will 
  remain 
  fairly 
  constant 
  until 
  about 
  | 
  of 
  the 
  gas 
  has 
  

   ■evaporated, 
  and 
  then 
  the 
  remainder 
  of 
  the 
  gas 
  would 
  be 
  in 
  

   the 
  gaseous 
  condition, 
  and 
  during 
  its 
  escape 
  the 
  pressure 
  

   would 
  fall 
  from 
  the 
  steady 
  value 
  down 
  to 
  that 
  of 
  the 
  atmo- 
  

   sphere. 
  With 
  a 
  larger 
  bulk 
  of 
  gas 
  it 
  would 
  not 
  be 
  difficult 
  

   to 
  stop 
  the 
  experiment 
  before 
  all 
  the 
  gas 
  had 
  evaporated. 
  

  

  There 
  is 
  also 
  a 
  small 
  change 
  in 
  the 
  temperature 
  of 
  the 
  gas, 
  

   and 
  this 
  will 
  influence 
  results 
  slightly. 
  

  

  The 
  mean 
  result 
  deduced 
  from 
  these 
  experiments 
  is 
  that 
  

   carbonic 
  acid 
  in 
  passing 
  through 
  the 
  plug 
  is 
  cooled 
  by 
  

  

  P-894 
  C. 
  

  

  per 
  [atmosphere 
  difference 
  of 
  pressure, 
  at 
  a 
  temperature 
  of 
  

  

  * 
  Preston's 
  ' 
  Heat/ 
  p. 
  394. 
  

   M2 
  

  

  