the Thermodynamic Scale of Temperature. 313 
Table IT. 
i| 
Correct ion. 
Temp. 
j 
Correction. 
; Temp. 
Constant 
pressure 
thermouieler. 
■■ 
Constant 
volume 
thermometer.! 
Constant 
pressure 
thermometer. 
Constant 1 
\oluiiie 
thermometer. 
0° C. 


60° C. 
-•0163 
-0026 
10 
-•0074 
-0011 
70 
-•0138 
-0022 
20 
-0126 
-•0019 
80 
-■0102 
-•0016 
\ 30 
-•0159 
-0025 
*90 
- 0056 
-•00,)9 
40 
-•0175 
-•0027 
100 


50 
-0176 
-•0028 
On the Applicability of the foregoing Theory to actual 
Gas- Thermometers. 
The numerical results given in the tables of last Section 
show that the thermodynamic corrections to the constant- 
volume thermometer are small quantities, when we employ 
hvdrogen or nitrogen at standard density ; and it becomes 
of importance to examine what sort of relation these 
corrections bear to the mistakes of reading due to the un- 
avoidable errors of experiment. It has been already 
remarked that in the case of hydrogen the nature of the 
walls of the containing vessel appears to exert a perceptible 
inlluence upon the pressure of the gus. Great interest 
therefore attaches to a careful comparison, carried out by 
M. Chappuis, between the readings of two hydrogen thermo- 
meters, both used at constant-volume, but differing in the mate- 
rial of their bulbs. The following figures were obtained : — 
Table III. 
Temperature. 
- 1 
Excess of reading of mercury-in-glass 
thermometer over constant-volume 
hydrogen thermometer with : 
Glass reservuir. 
Metai reservoir. 
10° C. 
20 
30 
40 
•051 
•076 
•095 
•108 
•052 
•085 
•102 
•107 
(Trav. et Mem. du Bur. Int. xiii. p. 39). The pressure at 
