﻿502 
  

  

  MR 
  W. 
  J. 
  M. 
  RANKINE 
  

  

  To 
  enable 
  others 
  to 
  judge 
  of 
  the 
  accuracy 
  of 
  this 
  result, 
  I 
  shall 
  now 
  explain 
  

   the 
  method 
  by 
  which 
  it 
  was 
  obtained, 
  annexing 
  a 
  copy 
  of 
  the 
  diagram 
  used. 
  

  

  Let 
  E 
  denote 
  the 
  mean 
  rate 
  of 
  increase, 
  per 
  degree, 
  between 
  the 
  freezing 
  and 
  

   boiling 
  points, 
  of 
  the 
  pressure 
  of 
  a 
  gas 
  whose 
  volume 
  is 
  maintained 
  constant. 
  

  

  Then 
  the 
  reciprocal 
  of 
  this 
  coefficient, 
  ^- 
  ■> 
  is 
  an 
  approximation 
  to 
  the 
  number 
  of 
  

  

  degrees 
  below 
  the 
  freezing 
  point, 
  at 
  which 
  the 
  absolute 
  zero 
  is 
  situated. 
  

  

  The 
  experimental 
  data 
  in 
  the 
  following 
  table 
  were 
  copied 
  from 
  the 
  memoirs 
  

   of 
  M. 
  Regnault 
  on 
  the 
  Expansion 
  of 
  Gases. 
  The 
  numbers 
  in 
  the 
  first 
  column 
  

   designate 
  the 
  series 
  of 
  experiments. 
  The 
  second 
  column 
  contains 
  the 
  pressures 
  

   of 
  the 
  gases 
  at 
  the 
  freezing 
  point. 
  The 
  third 
  column 
  contains 
  the 
  mean 
  coefficients 
  

   of 
  increase 
  of 
  pressure 
  per 
  centigrade 
  degree, 
  between 
  0° 
  and 
  100° 
  centigrade. 
  

   The 
  fourth 
  column 
  contains 
  the 
  reciprocals 
  of 
  those 
  coefficients, 
  with 
  the 
  negative 
  

   sign, 
  being 
  approximate 
  positions 
  of 
  the 
  absolute 
  zero, 
  in 
  centigrade 
  degrees, 
  below 
  

   the 
  temperature 
  of 
  melting 
  ice. 
  The 
  gases 
  employed 
  were 
  atmospheric 
  air 
  and 
  

   carbonic 
  acid. 
  

  

  No. 
  

  

  Pressure 
  at 
  

   0° 
  Centigrade 
  

  

  in 
  

   Atmospheres. 
  

  

  Coefficient 
  of 
  in- 
  

   crease 
  of 
  Elasticity 
  

   with 
  Temperature 
  

   = 
  E. 
  

  

  Approximate 
  positions 
  

   of 
  the 
  absolute 
  zero 
  

   in 
  Centigrade 
  degrees 
  

  

  _ 
  1 
  

  

  ~E 
  

  

  

  

  CARBONIC 
  ACIE 
  

  

  . 
  

  

  1. 
  

  

  0-9980 
  

  

  0-0036856 
  

  

  -27°1'33 
  

  

  2. 
  

  

  1-1857 
  

  

  0-0036943 
  

  

  -270-63 
  

  

  3. 
  

  

  2-2931 
  

  

  0-0037523 
  

  

  -266-50 
  

  

  4. 
  

  

  4-7225 
  

  

  0-0038598 
  

  

  -259-08 
  

  

  

  j 
  

  

  ATMOSPHERIC 
  A 
  

  

  [R. 
  

  

  1. 
  

  

  0-1444 
  

  

  00036482 
  

  

  -27411 
  

  

  2. 
  

  

  0-2294 
  

  

  0-0036513 
  

  

  -273-88 
  

  

  3. 
  

  

  0-3501 
  

  

  0-0036542 
  

  

  -273-66 
  

  

  4. 
  

  

  0-4930 
  

  

  0-0036587 
  

  

  -273-32 
  

  

  5. 
  

  

  0-4937 
  

  

  0-0036572 
  

  

  -273-43 
  

  

  6. 
  

  

  1-0000 
  

  

  0-0036650 
  

  

  -272-85 
  

  

  7. 
  

  

  2-2084 
  

  

  0-0036760 
  

  

  -272-03 
  

  

  8. 
  

  

  2-2270 
  

  

  0-0036800 
  

  

  -271-74 
  

  

  9. 
  

  

  2-8213 
  

  

  0-0036894 
  

  

  -271-05 
  

  

  10. 
  

  

  4-8100 
  

  

  0-0037091 
  

  

  -269-61 
  

  

  