﻿the 
  Vapour-Pressure 
  of 
  Mercury. 
  793 
  

  

  observations 
  ; 
  and 
  it 
  was 
  clear 
  that 
  one 
  three-constants 
  

   formula 
  would 
  not 
  fit 
  all 
  the 
  observations 
  as 
  closely 
  as 
  was 
  

   desirable. 
  The 
  graph 
  of 
  the 
  last 
  formula, 
  however, 
  showed 
  

  

  1-60 
  

  

  that 
  two 
  Kirchhoff 
  formulae 
  could 
  be 
  found, 
  which 
  would 
  fit 
  

   the 
  observations 
  as 
  closely 
  as 
  was 
  required 
  by 
  the 
  con- 
  

   cordance 
  and 
  accuracy 
  of 
  the 
  experiments 
  concerned. 
  These 
  

   formulas 
  are 
  : 
  — 
  

  

  logp 
  = 
  15-24431 
  -3623*932/0-2*367233 
  log 
  6, 
  . 
  (M) 
  

   derived 
  from 
  

  

  41°*7, 
  ldgp=3'8157 
  ; 
  190°, 
  1*1072 
  ; 
  270°, 
  2'0965 
  ; 
  

   and 
  logjp= 
  1O-O4O87-3271-245/0- 
  -7020537 
  log 
  0, 
  (L) 
  

   derived 
  from 
  

  

  16, 
  4*994 
  ; 
  270°, 
  2*0965 
  ; 
  356°-7, 
  2*8808. 
  

  

  The 
  following 
  Table 
  shows 
  how 
  closely 
  these 
  formula? 
  fit 
  

   the 
  observations. 
  M 
  is 
  used 
  from 
  15° 
  to 
  270°, 
  and 
  L 
  

   from 
  270° 
  to 
  450 
  c 
  , 
  to 
  calculate 
  log 
  p. 
  Under 
  A 
  is 
  given 
  

   {logjj 
  observed) 
  — 
  (log 
  p 
  calculated), 
  and 
  under 
  2A 
  is 
  given 
  

   the 
  sum 
  of 
  the 
  A's 
  for 
  each 
  group. 
  

  

  