312 Mr. J. Rose-Inn es on the Practical Attainment of 
possible that even at lower temperatures some slight inter- 
action may take place between the walls of a metal vessel 
and the enclosed gas (" L'echelle thermometrique normale et 
les echelles pratiques," pp. 3-4). For these reasons I prefer to 
lake the figure '00366217 as the most probable value for the 
coefficient of the increase of pressure at constant volume ; 
we thus obtain 273'002 as the "uncorrected estimate " of 
the freezing-point of water. By employing the values of the 
constants given at the end of last Section, we may readily 
calculate that the proper correction to be applied is 0°'0ti'J, 
so that we obtain 273 '131 as the estimate of the freezing- 
point. 
The thermodynamic corrections to the readings of the 
hydrogen thermometer are given in the following Table : — 
Table I. 
Temp. 
; C. 
Correction. 
Temp. 
Correction. 
Constant 
pressure 
thermuiuet^r. 
Constant 
volume 
ihermometer. 
Constant 
pressure 
thermometer. 
Constant 
volume 
thermometer. 

oo c C. 
-0023 
-0015 
JO 
-•0OIL 
-•0007 
70 
-•0019 
-•0013 
20 
- -001 8 
-0012 
80 
- -0014 
-•0010 
30 
-0023 
-0015 
90 
-•0008 
-•0005 
40 
-■0025 
-0016 
100 


50 
-•0025 
-001 6 
The constant-pressure thermometer is supposed to be under 
the pressure of 1 atmosphere, and the constant-volume 
thermometer is supposed to be under the pressure of 
] atmosphere at the freezing-point. 
Nitrogen. — \Ye saw that M. Chappuis's value for the 
coefficient of expansion at a constant pressure of 1'002 m. 
was "00367315 ; from this figure we obtain 272°'246 as the 
" uncorrected estimate ,! of the freezing-point of water. We. 
mav emplov the values of the constants given at the end 
of last Seel ion to calculate the necessary correction : we 
easily find that it is equal to 0° 890. Hence we obtain 
273°'13b as the '* corrected estimate" of the freezing-point. 
The following Table gives the thermodynamic corrections 
for the constant-pressure thermometer under 1 atmosphere 
pressure, and for the constant-volume thermometer having 
the pressure of 1 atmosphere at the freezing-point : — 
