﻿376 
  Mr. 
  R. 
  A. 
  Lehfeldt 
  on 
  a 
  Numerical 
  Evaluation 
  of 
  

  

  value 
  of 
  this 
  quantity 
  instead 
  of 
  Chappuis's, 
  T 
  will 
  come 
  out 
  

   much 
  closer 
  to 
  273°, 
  and 
  it 
  would 
  probably 
  be 
  right 
  to 
  do 
  so, 
  

   since 
  the 
  experiments 
  of 
  Regnault 
  covered 
  a 
  wide 
  range 
  of 
  

   density, 
  whereas 
  only 
  two 
  densities, 
  near 
  together, 
  were 
  used 
  

   at 
  the 
  Bureau 
  International. 
  The 
  numbers 
  derived 
  from 
  

   carbon 
  dioxide 
  cannot, 
  however, 
  be 
  allowed 
  much 
  weight 
  in 
  

   the 
  result, 
  at 
  present 
  ; 
  a 
  fresh 
  set 
  of 
  experiments 
  on 
  the 
  

   cooling 
  effect, 
  carried 
  out 
  with 
  the 
  pure 
  gas, 
  and 
  over 
  a 
  

   considerable 
  range 
  of 
  temperature, 
  is 
  needed 
  to 
  make 
  the 
  

   conclusions 
  trustworthy; 
  while 
  determinations 
  of 
  the 
  coeffi- 
  

   cient 
  of 
  pressure 
  for 
  lower 
  densities, 
  not 
  only 
  for 
  carbon 
  

   dioxide 
  but 
  for 
  all 
  the 
  gases, 
  including 
  air, 
  would 
  give 
  most 
  

   valuable 
  information. 
  

  

  The 
  results, 
  allowing 
  for 
  such 
  possible 
  corrections 
  as 
  we 
  

   have 
  just 
  indicated, 
  seem 
  to 
  point 
  to 
  the 
  conclusion 
  that 
  the 
  

   freezing-point 
  is 
  within 
  a 
  tenth 
  of 
  a 
  degree 
  of 
  273° 
  absolute. 
  

  

  Results: 
  — 
  (ii.) 
  Comparison 
  of 
  the 
  Thermodynamic 
  with 
  Actual 
  

  

  Scales. 
  

   To 
  reduce 
  temperatures 
  on 
  a 
  gas 
  scale, 
  we 
  have 
  from 
  (iv.) 
  

  

  log(T/T 
  )= 
  * 
  l 
  gl±i^, 
  . 
  . 
  . 
  (vii.) 
  

  

  .-K 
  P 
  6/l7 
  rt 
  1//5 
  ' 
  

   in 
  w 
  r 
  hich 
  K 
  P 
  and 
  e 
  are 
  to 
  have 
  their 
  mean 
  values 
  over 
  the 
  

   range 
  0° 
  to 
  t°. 
  For 
  hydrogen 
  these 
  are 
  assumed 
  to 
  be 
  constant 
  

   (for 
  want 
  of 
  better 
  information) 
  and 
  equal 
  to 
  their 
  values 
  

   between 
  0° 
  and 
  100°, 
  so 
  that 
  

  

  l-K 
  P 
  e/i? 
  = 
  0-9993 
  

   tis 
  before. 
  For 
  nitrogen 
  the 
  values 
  of 
  e 
  are 
  taken 
  as 
  those 
  

   read 
  off 
  the 
  curve 
  of 
  experimental 
  data 
  for 
  air, 
  and 
  are 
  as 
  

   follows 
  : 
  — 
  

  

  K 
  P 
  = 
  10,200,000 
  ; 
  v= 
  608 
  c.c. 
  

  

  

  t 
  

  

  Mean 
  of 
  e 
  

   0° 
  to 
  t°. 
  

  

  1-Kpe/fl. 
  

  

  

  10 
  

  

  -0261 
  

  

  10043 
  

  

  

  20 
  

  

  •255 
  

  

  42 
  

  

  

  SO 
  

  

  •249 
  

  

  41 
  

  

  

  40 
  

  

  •242 
  

  

  40 
  

  

  

  50 
  

  

  •235 
  

  

  39 
  

  

  

  60 
  

  

  •228 
  

  

  38 
  

  

  

  70 
  

  

  •221 
  

  

  37 
  

  

  

  80 
  

  

  •214 
  

  

  36 
  

  

  

  90 
  

  

  •207 
  

  

  35 
  

  

  

  100 
  

  

  •200 
  

  

  34 
  

  

  