Diu M. W. TKAYEliS, Mil. C4. SEXTEE, AXE DK. A. JAQUEKOD 
17. The boiliiig-poiiit. 1’21 
18. Calculation of the results. 122 
19. The details of one experiment.123 
20. The pressure coefficient of hydrogen... 12-3 
21. The pre.ssure coefficient of helium.128 
22. The accuracy of the results. 131 
23. The final values for the pressure coefficients of hydrogen and helium.131 
21:. The pressure coefficients of hytbogen and helium at lower initial in’essures .... 133 
2-5. General conclusions . . 133 
1. Introduction. 
CoxsiDERiXG how much depends upon our knowledge of the relationship betAveen 
the thermodynamic scale of temperature and the various scales of temperature as 
determined by means of gas thermometers, it is surprising that so little attention 
has been paid to the matter in recent years. Indeed, instead of attempting to arrive 
at the necessary experimental data for the solution of the j^roblem, it appears as if 
chemists and physicists Avere prepared to accept arbitrary scales of temperature, 
AA’hich ditier considerably one from another. 
Since the problem Avas first attacked by Joule and Lord Kelvin, more than hall 
a centuiy ago, it has been made the subject of inA'estigation by more than one 
mathematician. Itecently {‘ Phil. Mag.,’ 1901, Ami. 2, p. 130) J. IIo.se-Inxes has 
succeeded in developing some fairly simple equations by means of AA'hich the difierence 
hetAveen the thermo-dynamic scale of temperature and the temperature determined 
by means of gas thermometers can be calculated. The data nece.ssary in the case ot 
each gas are the folloAving:— 
(«.) The coefficient of increase of pressure at constant A’olume, 
(h.) The coefficient of increase of Amlume at constant pressure. 
(c.) The A'ariation of “p.A’.” Avith pressure at difierent temperature. 
(d.) The Joule-Tliomson effect and its Amriation with temperature. 
Applying existing data to his equations, Eose-Innes arriA*ed at results AA'hich, as 
tlie folloAving table shoAvs, are anything but satisfactory : — 
Correction of the Constant-Volume Thermometer. 
Ga.s. 
Pressure on 
gas at ice-point. 
Teiiq^erature of ice- 
point (reciprocal of 
pressure coefficient). 
Correction. 
Absolute ice- 
point. 
Hydrogen. 
iiiillims. 
1000 
273-01 
0-12 
273-16 
Xiti’ogeii. 
995 
272-13 
1-23 
273-36 
