﻿DYNAMICAL 
  THEORY 
  OF 
  HEAT. 
  

  

  28^ 
  

  

  lated 
  : 
  with, 
  besides, 
  the 
  following 
  data 
  afforded 
  by 
  Regnault 
  from 
  his 
  observa- 
  

   tions 
  on 
  the 
  total 
  heat 
  of 
  steam, 
  and 
  the 
  specific 
  heat 
  of 
  water 
  

  

  dt 
  

  

  + 
  c= 
  -305. 
  

  

  L 
  = 
  606-5 
  + 
  -305 
  t- 
  (-00002 
  f 
  + 
  -0000003 
  t 
  s 
  ). 
  

  

  The 
  values 
  of 
  —h 
  shewn 
  in 
  the 
  third 
  column 
  are 
  those 
  derived 
  by 
  Clausius 
  from 
  

  

  E 
  

   an 
  equation 
  which 
  is 
  the 
  same 
  as 
  what 
  (34) 
  would 
  become 
  if 
  J 
  = 
  — 
  ^- 
  were 
  substi- 
  

   tuted 
  for 
  /jl. 
  

  

  

  — 
  h 
  according 
  to 
  

  

  

  

  Table 
  I. 
  of 
  "Ac- 
  

  

  — 
  h 
  according 
  to 
  

  

  1 
  

  

  count 
  of 
  Carnot's 
  

   Theory." 
  

  

  Clausius. 
  

  

  

  

  1-863 
  

  

  1-916 
  

  

  50 
  

  

  1-479 
  

  

  1-465 
  

  

  100 
  

  

  1-174 
  

  

  1-133 
  

  

  150 
  

  

  0-951 
  

  

  0-879 
  

  

  200 
  

  

  i 
  

  

  0-780 
  

  

  0-676 
  

  

  59. 
  From 
  these 
  results, 
  it 
  appears 
  that 
  through 
  the 
  whole 
  range 
  of 
  tempera- 
  

   tures 
  at 
  which 
  observations 
  have 
  been 
  made, 
  the 
  value 
  of 
  h 
  is 
  negative 
  ; 
  and, 
  

   therefore, 
  if 
  a 
  quantity 
  of 
  saturated 
  vapour 
  be 
  compressed 
  in 
  a 
  vessel 
  containing 
  

   no 
  liquid 
  water, 
  heat 
  must 
  be 
  continuously 
  abstracted 
  from 
  it 
  in 
  order 
  that 
  it 
  may 
  

   remain 
  saturated 
  as 
  its 
  temperature 
  rises 
  ; 
  and 
  conversely, 
  if 
  a 
  quantity 
  of 
  satu- 
  

   rated 
  vapour 
  be 
  allowed 
  'to 
  expand 
  in 
  a 
  closed 
  vessel, 
  heat 
  must 
  be 
  supplied 
  to 
  it 
  

   to 
  prevent 
  any 
  part 
  of 
  it 
  from 
  becoming 
  condensed 
  into 
  the 
  liquid 
  form 
  as 
  the 
  

   temperature 
  of 
  the 
  whole 
  sinks. 
  This 
  very 
  remarkable 
  conclusion 
  was 
  first 
  

   announced 
  by 
  Mr 
  Rankine, 
  in 
  his 
  paper 
  communicated 
  to 
  this 
  Society 
  on 
  the 
  

   4th 
  of 
  February 
  last 
  year. 
  It 
  was 
  discovered 
  independently 
  by 
  Clausius, 
  and 
  

   published 
  in 
  his 
  paper 
  in 
  Poggendorff's 
  Annalen 
  in 
  the 
  months 
  of 
  April 
  and 
  May 
  

   of 
  the 
  same 
  year. 
  

  

  60. 
  It 
  might 
  appear 
  at 
  first 
  sight, 
  that 
  the 
  well-known 
  fact, 
  that 
  steam 
  rush- 
  

   ing 
  from 
  a 
  high-pressure 
  boiler 
  through 
  a 
  small 
  orifice 
  into 
  the 
  open 
  air, 
  does 
  not 
  

   scald 
  a 
  hand 
  exposed 
  to 
  it, 
  is 
  inconsistent 
  with 
  the 
  proposition, 
  that 
  steam 
  

   expanding 
  from 
  a 
  state 
  of 
  saturation 
  must 
  have 
  heat 
  given 
  to 
  it 
  to 
  prevent 
  any 
  

   part 
  from 
  becoming 
  condensed 
  ; 
  since 
  the 
  steam 
  would 
  scald 
  the 
  hand 
  unless 
  it 
  

   were 
  dry, 
  and 
  consequently 
  above 
  the 
  boiling 
  point 
  in 
  temperature. 
  The 
  explana- 
  

   tion 
  of 
  this 
  apparent 
  difficulty, 
  given 
  in 
  a 
  letter 
  which 
  I 
  wrote 
  to 
  Mr 
  Joule 
  

   last 
  October, 
  and 
  which 
  has 
  since 
  been 
  published 
  in 
  the 
  Philosophical 
  Magazine,* 
  

  

  * 
  This 
  explanation 
  Las 
  been 
  objected 
  to 
  as 
  incorrect 
  in 
  principle 
  by 
  Clausius, 
  in 
  an 
  article 
  

   recently 
  published 
  in 
  Poggendorff's 
  Annalen. 
  I 
  trust 
  that, 
  on 
  reconsidering 
  the 
  subject 
  (and, 
  

   should 
  this 
  meet 
  his 
  eye, 
  on 
  reading 
  the 
  statement 
  in 
  the 
  text, 
  and 
  the 
  remarks 
  in 
  § 
  33 
  above), 
  he 
  

   will 
  perceive 
  that 
  my 
  explanation, 
  as 
  originally 
  stated, 
  is 
  perfectly 
  correct. 
  

  

  