﻿Pressure, 
  and 
  Latent 
  Heat 
  of 
  Vaporization. 
  395 
  

  

  Table 
  II. 
  

  

  Ref 
  - 
  Name 
  

   No: 
  ^ 
  ame 
  - 
  

  

  Formula. 
  

  

  Molec- 
  

   ular 
  

   Mass. 
  

  

  Latent 
  

   Heat. 
  

  

  TaZ)s 
  

  

  2 
  log 
  p. 
  

  

  

  a 
  

   I 
  Benzene 
  

  

  b 
  

   C 
  6 
  H 
  6 
  

  

  CHC1 
  3 
  

   CC1 
  4 
  

   CS 
  2 
  

  

  (C 
  2 
  H 
  5 
  ) 
  2 
  

  

  CsTI 
  6 
  02 
  

  

  C4H 
  8 
  02 
  

  

  C 
  3 
  H 
  6 
  2 
  

   C4H8O2 
  

  

  c 
  

  

  78 
  

  

  78 
  

   119-4 
  

   156 
  

  

  76 
  

   76 
  

  

  74 
  

   74 
  

   74 
  

   88 
  

   74 
  

   88 
  

  

  d 
  

  

  107-6 
  

  

  109-0 
  

  

  67-0 
  

  

  52-0 
  

  

  90-0 
  

  

  89-5 
  

  

  93-5 
  

  

  94-0 
  

  

  11325 
  

  

  105-37 
  

  

  113-86 
  

  

  102-14 
  

  

  30-75 
  

   31-14 
  

   29-20 
  

   29-25 
  

   25-00 
  

   25-09 
  

   25-21 
  

   25-49 
  

   30-69 
  

   33-96 
  

   30-86 
  

   32-92 
  

  

  f 
  

  

  98 
  

  

  9-8 
  

  

  12-85 
  

  

  1221 
  

  

  14-92 
  

  

  14-92 
  

  

  15-67 
  

  

  15-67 
  

  

  9-8 
  

  

  9-8 
  

  

  9-8 
  

  

  9-8 
  

  

  / 
  and 
  e 
  

   40-55 
  

  

  II 
  

  

  40-94 
  

  

  II 
  Chloroform 
  

  

  42-05 
  

  

  II 
  Carbon 
  tetrachloride 
  ._ 
  

   II 
  Carbon 
  disulphide 
  

  

  III 
  " 
  

  

  III 
  Ethyl 
  ether 
  

  

  41-46 
  

   39-92 
  

   40-07 
  

  

  40-87 
  

  

  II 
  " 
  " 
  

  

  41-16 
  

  

  I 
  Ethyl 
  f 
  ormiate 
  

  

  I 
  Propyl 
  f 
  ormiate 
  

  

  I 
  Methyl 
  acetate 
  

  

  I 
  Ethyl 
  acetate 
  

  

  40-49 
  

   43-76 
  

   40-09 
  

   42-72 
  

  

  I, 
  Jahn, 
  Zeitschr. 
  f. 
  phys. 
  Chem., 
  xi, 
  790, 
  1893. 
  

  

  IT, 
  Eegnault, 
  Memoires 
  de 
  l'Academie, 
  xxvi, 
  761, 
  1862. 
  

  

  Ill, 
  Winkelmann, 
  Wiedemann's 
  Annalen, 
  ix, 
  208 
  and 
  358, 
  1880. 
  

  

  Table 
  II 
  shows 
  that, 
  while 
  it 
  is 
  impossible 
  to 
  speak 
  of 
  a 
  

   constancy 
  for 
  the 
  values 
  contained 
  in 
  the 
  sixth 
  column, 
  through 
  

   the 
  introduction 
  of 
  the 
  pressure 
  correction 
  in 
  equation 
  (17) 
  a 
  

   value 
  is 
  found 
  equal 
  in 
  mean 
  to 
  about 
  40*5 
  ; 
  it 
  is 
  remarkable 
  

   that 
  such 
  a 
  constancy 
  is 
  to 
  be 
  found 
  in 
  the 
  values, 
  since 
  no 
  

   great 
  amount 
  of 
  accuracy 
  can 
  be 
  attributed 
  to 
  the 
  determina- 
  

   tions 
  of 
  the 
  latent 
  heat 
  or 
  of 
  the 
  pressure. 
  If 
  the 
  pressure 
  

   correction 
  be 
  applied 
  to 
  the 
  determinations 
  of 
  the 
  latent 
  heats 
  

   of 
  vaporization 
  carried 
  out 
  under 
  or 
  nearly 
  under 
  atmospheric 
  

   pressure, 
  the 
  "constant" 
  is 
  found 
  to 
  become 
  equal 
  to 
  39' 
  18, 
  

   since 
  2 
  log 
  760 
  equals 
  18*48 
  ; 
  this 
  value, 
  as 
  is 
  to 
  be 
  expected, 
  

   is 
  very 
  near 
  to 
  that 
  found 
  for 
  the 
  liquids 
  under 
  the 
  circum- 
  

   stances 
  given 
  in 
  table 
  II 
  ; 
  undoubtedly, 
  approximately 
  the 
  

   same 
  value 
  for 
  the 
  expression 
  would 
  be 
  found 
  under 
  other 
  

   pressures 
  and 
  concurrent 
  temperatures, 
  although 
  the 
  data 
  at 
  

   hand 
  are 
  too 
  meager 
  to 
  make 
  it 
  worth 
  while 
  to 
  perform 
  the 
  

   necessary 
  calculations. 
  As 
  a 
  conclusion 
  to 
  all 
  that 
  precedes 
  

   and 
  as 
  a 
  prediction 
  of 
  all 
  future 
  experimental 
  work 
  on 
  latent 
  

   heats 
  of 
  vaporization, 
  it 
  may 
  be 
  stated 
  that 
  the 
  relation 
  deduced 
  

   by 
  Le 
  Chatelier 
  may 
  be 
  put 
  equal 
  to 
  about 
  40*00, 
  thus 
  

  

  2lo 
  ^+T^ 
  = 
  40 
  - 
  00 
  

  

  (17 
  bis) 
  

  

  IY. 
  

  

  In 
  accurate 
  determinations 
  of 
  temperatures 
  of 
  ebullition, 
  it 
  

   is 
  often 
  necessary 
  to 
  make 
  a 
  correction 
  for 
  the 
  variation 
  of 
  the 
  

   pressure 
  from 
  the 
  normal 
  pressure 
  of 
  760 
  mm 
  of 
  mercury. 
  In 
  

  

  