﻿Dr. 
  P. 
  Chappuis 
  on 
  Gas- 
  Thermometry 
  . 
  

  

  245 
  

  

  T. 
  

  

  Harker 
  & 
  

  

  Chappuis, 
  

  

  Holborn 
  & 
  Wien, 
  

  

  Holborn 
  & 
  Day 
  

  

  1808. 
  

  

  1892. 
  

  

  1900. 
  

  

  0° 
  

  

  2690 
  xlO- 
  9 
  

  

  

  2954 
  x 
  10- 
  9 
  

  

  100° 
  

  

  2989 
  

  

  

  

  3066 
  „ 
  

  

  200° 
  

  

  (3288) 
  

  

  n 
  

  

  

  3179 
  „ 
  

  

  300° 
  

  

  (3587; 
  

  

  n 
  

  

  

  3291 
  „ 
  

  

  400° 
  

  

  (3886) 
  

  

  „ 
  

  

  

  3404 
  „ 
  

  

  500° 
  

  

  (4185) 
  

  

  n 
  

  

  

  3516 
  „ 
  

  

  600° 
  

  

  (4484) 
  

  

  ii 
  

  

  4400 
  X 
  10-9 
  

  

  3629 
  „ 
  

  

  At 
  the 
  time 
  of 
  our 
  experiments 
  the 
  absence 
  of 
  precise 
  data 
  

   for 
  the 
  expansion 
  of 
  porcelain 
  compelled 
  us 
  to 
  deduce 
  the 
  

   values 
  for 
  the 
  higher 
  temperatures 
  by 
  extrapolation 
  of 
  the 
  

   expression 
  determined 
  between 
  the 
  limits 
  0° 
  and 
  100°. 
  The 
  

   values 
  we 
  thus 
  obtained 
  seemed 
  to 
  be 
  confirmed 
  by 
  Messrs. 
  

   Holborn 
  and 
  Wien, 
  but 
  are 
  not 
  in 
  agreement 
  with 
  the 
  new 
  

   experiments 
  of 
  Messrs. 
  Holborn 
  and 
  Day. 
  

  

  The 
  following 
  diagram 
  represents 
  the 
  mean 
  coefficients 
  as 
  

   given 
  bv 
  our 
  determination 
  and 
  that 
  of 
  Messrs. 
  Holborn 
  and 
  

   Day. 
  

  

  5000x10" 
  

  

  4000X10" 
  

  

  3000x10" 
  

  

  2000x10" 
  

  

  1000X10' 
  

  

  0X10" 
  

  

  --- 
  ■ 
  

  

  0° 
  

  

  100° 
  

  

  400° 
  

  

  600° 
  

  

  Since 
  the 
  formula 
  of 
  Messrs. 
  Holborn 
  and 
  Day 
  gives 
  too 
  high 
  

   values 
  for 
  temperatures 
  below 
  250° 
  the 
  curve 
  should 
  approach 
  

   ours 
  in 
  this 
  region. 
  It 
  is 
  evident 
  from 
  the 
  diagram 
  that 
  

   there 
  is 
  therefore 
  no 
  incompatibility 
  between 
  their 
  results 
  and 
  

   ours, 
  and 
  that 
  they 
  may 
  be 
  considered 
  as 
  approximate 
  values 
  

   of 
  the 
  same 
  function 
  representing 
  the 
  expansion 
  of 
  Berlin 
  

   porcelain. 
  

  

  Although 
  there 
  may 
  be 
  doubts 
  as 
  to 
  the 
  identity 
  of 
  the 
  

   material 
  subjected 
  to 
  experiments 
  in 
  the 
  two 
  cases, 
  and 
  even 
  

   as 
  to 
  the 
  invariability 
  of 
  the 
  properties 
  of 
  a 
  single 
  specimen, 
  

   w 
  r 
  hen 
  subjected 
  on 
  several 
  occasions 
  to 
  a 
  lengthy 
  annealing 
  

   process, 
  it 
  seemed 
  to 
  me 
  interesting 
  to 
  recalculate 
  some 
  of 
  

   our 
  observations 
  on 
  the 
  boiling-point 
  of 
  sulphur, 
  assuming 
  

   for 
  the 
  mean 
  coefficient 
  of 
  expansion 
  of 
  the 
  reservoir 
  the 
  

  

  