﻿162 
  

  

  Prof. 
  W. 
  A. 
  Douglas 
  Rudge 
  on 
  

  

  amount 
  of 
  gas 
  origiually 
  filling 
  it 
  found. 
  This 
  averaged 
  

   about 
  4'5 
  grammes. 
  The 
  internal 
  volume 
  of 
  the 
  bulb 
  was 
  

   about 
  5*35 
  c.c. 
  

  

  The 
  heat 
  absorbed 
  was 
  found 
  as 
  usual 
  by 
  multiplying 
  the 
  

   water 
  equivalent 
  of 
  the 
  calorimeter 
  and 
  its 
  contents 
  by 
  the 
  

   change 
  in 
  temperature, 
  the 
  water 
  equivalent 
  being 
  found 
  by 
  

   sending 
  a 
  current 
  of 
  known 
  strength 
  through 
  the 
  manganin 
  

   coil 
  and 
  calculating 
  its 
  value 
  from 
  H 
  = 
  C^RT. 
  The 
  liquid 
  in 
  

   the 
  calorimeter 
  was 
  generally 
  water, 
  paraffin 
  was 
  occasionally 
  

   used, 
  but 
  as 
  different 
  samples 
  showed 
  variations 
  in 
  the 
  specific 
  

   heat 
  it 
  was 
  considered 
  best 
  to 
  adhere 
  to 
  water. 
  

  

  A 
  typical 
  experiment 
  gave 
  the 
  following 
  figures 
  : 
  — 
  

  

  Weight 
  of 
  bulb 
  full 
  of 
  gas 
  17-31 
  grms. 
  

  

  , 
  „ 
  empty 
  12-91 
  „ 
  

  

  ?, 
  gas 
  4-40 
  „ 
  

  

  Temperature 
  before 
  escape 
  of 
  gas 
  22-25 
  °C. 
  

  

  Temperature 
  after 
  escape 
  20-35 
  „ 
  

  

  Fall 
  in 
  temperature 
  1-9 
  „ 
  

  

  Correction 
  -05, 
  total 
  fall 
  VQo 
  ,, 
  

  

  Duration 
  of 
  experiment 
  25 
  minutes. 
  

  

  Water 
  equivalent 
  134 
  units. 
  

  

  Heat 
  absorbed 
  261*3 
  „ 
  

  

  Latent 
  beat 
  of 
  4-4 
  grs. 
  of 
  gas 
  159*6 
  „ 
  

  

  Heat 
  absorbed 
  by 
  passing 
  through 
  the 
  plug 
  . 
  101-7 
  „ 
  

   *Cooling 
  of 
  the 
  gas 
  necessary 
  to 
  account 
  for 
  

  

  the 
  absorption 
  of 
  heat 
  110° 
  C. 
  

  

  Pressure 
  of 
  gas 
  at 
  commencement 
  of 
  ex- 
  

   periment 
  57-9 
  atmospheres. 
  

  

  Cooling 
  effect 
  per 
  atmosphere 
  1-9 
  nearly. 
  

  

  The 
  examples 
  in 
  the 
  following 
  table 
  are 
  selected 
  because 
  

   they 
  are 
  all 
  about 
  20° 
  C. 
  

  

  The 
  numbers 
  in 
  the 
  last 
  column 
  are 
  fairly 
  constant, 
  and 
  

   about 
  100 
  experiments 
  have 
  been 
  made 
  which 
  give 
  practically 
  

   the 
  same 
  range 
  in 
  the 
  numerical 
  differences. 
  

  

  * 
  The 
  calculated 
  value 
  of 
  the 
  cooling 
  was 
  obtained 
  by 
  assuming 
  the 
  

   Talue 
  of 
  the 
  specific 
  heat 
  of 
  the 
  gas 
  to 
  be 
  -21, 
  then 
  

  

  H=MxSx(^-0 
  

  

  H 
  

  

  Fall 
  in 
  temperature 
  {Q—t)= 
  TTTTg 
  

  

  