﻿160 
  

  

  Prof. 
  W. 
  A. 
  Douglas 
  Rudge 
  on 
  

  

  pressure 
  whose 
  value 
  can 
  be 
  found 
  from 
  the 
  tension 
  of 
  the 
  

   gas 
  at 
  the 
  temperature. 
  

  

  The 
  total 
  heat-change 
  occurring 
  in 
  a 
  calorimeter 
  during 
  

   the 
  escape 
  of 
  the 
  gas 
  will 
  be 
  : 
  — 
  

  

  (1) 
  The 
  heat 
  absorbed 
  during 
  evaporation. 
  

  

  (2) 
  „ 
  ,j 
  „ 
  change 
  in 
  temperature 
  of 
  

   the 
  gas. 
  

  

  (3) 
  The 
  heat 
  absorbed 
  by 
  the 
  Joule-Thomson 
  efEect. 
  

   (2) 
  is 
  a 
  small 
  quantity 
  in 
  the 
  experiments 
  described. 
  

  

  If 
  H=amount 
  of 
  heat 
  absorbed 
  from 
  the 
  calorimeter, 
  

   L 
  = 
  latent 
  heat 
  of 
  the 
  gas, 
  S 
  = 
  specific 
  heat, 
  M 
  = 
  mass, 
  and 
  

   K 
  = 
  change 
  of 
  temperature 
  due 
  to 
  the 
  passage 
  of 
  the 
  gas 
  

   through 
  the 
  plug 
  

  

  H 
  = 
  M,LH-(KxMxS), 
  

  

  H-M, 
  L_T^ 
  

   •'• 
  M,S 
  "■ 
  ' 
  

   and 
  if 
  P 
  = 
  the 
  difEerence 
  in 
  pressure 
  on 
  the 
  two 
  sides 
  of 
  the 
  

  

  plug 
  p^=^ 
  = 
  change 
  in 
  temperature 
  per 
  atmosphere 
  dif- 
  

   ference 
  of 
  pressure, 
  the 
  assumption 
  being 
  made 
  that 
  the 
  

   specific 
  heat 
  remains 
  constant. 
  

  

  Fig. 
  1. 
  

  

  P. 
  Plug 
  chamber. 
  M. 
  Manganin 
  coil. 
  

   W. 
  Turbine. 
  T^ 
  and 
  Tg. 
  Thermometers. 
  

  

  The 
  apparatus 
  (fig. 
  1) 
  used 
  consisted 
  of 
  a 
  small 
  oval-shaped 
  

   calorimeter 
  made 
  of 
  brass 
  in 
  which 
  the 
  plug 
  was 
  placed. 
  

   The 
  plug 
  itself 
  was 
  a 
  small 
  brass 
  vessel 
  with 
  a 
  gas-tight 
  cap 
  

  

  