OF GASES AT CONSTANT VOLUME. 
967 
potash, and a volume of O'l 1 cub. centiin. unabsorbed gas remained in the tube. 
The impurity is therefore about one part in 550 by volume. The drying was effected 
by filling from the bottle through an iron drying tube containing fresh phosphorus 
pentoxide. The one sample of gas was used throughout the several series of experi¬ 
ments ; known weights being released at intervals. 
The thermometers were made by Messrs. Negretti and Zambra, and corrected at 
Kew. They were four in number, to secure open scales : 0° to 20°, 20° to 50°, 50° to 70°, 
and 70° to 100°. In the following tables of sets of experiments it will be understood 
that the initial temperature of 78° is obtained by a jacket of the vapour of absolute 
ethyl alcohol boiling under atmospheric pressure ; the temperature, 56° by acetone 
vapour, 35° by pure ether ; the lowest initial temperature being air temperature. 
It will be noticed that the density given in the several tables varies to some extent 
even with the same value of W. This is due to the thermal-pressure corrections on 
the volume of the vessel varying with the range. 
The tables give, in addition to the initial and final temperatures, the range and 
the latent heat of steam at t^. The values in the column “ w ” are the gross effects 
produced upon the balance. The portion of this effect due to the inequalities of 
volume and thermal capacities of the vessels is given beneath, as well as the sum 
of all other corrections, needing notice, due to the dynamical or buoyant effects set up 
by the gas in the active sphere, ts is the balance of w, or precipitation, due to the 
calorific capacity of the quantity, W, of gas, at constant volume, over the range 
obtaining. On this the mean specific heat over the range is calculated. 
Table II.—W = 17‘6658, Mean Density = 0’1971. 
Mean Pressure = 97 Atmospheres. 
h- 
h- 
X. 
u — q. 
n>. 
7777 
99-55 
.536-9 
21-78 
0-1554 
77-97 
99-82 
536-7 
21-85 
0-1.547 
77-77 
99-55 
536-9 
21-80 
0-1557 
77-84 
99-64 
536-8 
21-80 
0-1553 
Coi’rection for spheres = — 0’00886. 
Other corrections = — 0’00054. w — 0T4.59. 
Deduced specific heat = 0‘20337. 
