Page:Reflections on the Motive Power of Heat.djvu/267

pressure, and c a constant quantity depending on the weight of the vapor and on the units chosen. We give here the table of the volumes occupied by a gramme of vapor formed at different temperatures, and consequently under different pressures.

t or degrees Centigrade.	p or tension of the vapor expressed in millimetres of mercury.	v or volume of a gramme of vapor expressed in litres.
°	mm.	lit.
0	5.060	185.0
20	17.32	58.2
40	53.00	20.4
60	144.6	7.96
80	352.1	3.47
100	760.0	1.70

The first two columns of this table are taken from the Traité de Physique of M. Biot (vol. i., p. 272 and 531). The third is calculated by means of the above formula, and in accordance with the result of experiment, indicating that water vaporized under atmospheric pressure occupies a space 1700 times as great as in the liquid state.

By using three numbers of the first column and three corresponding numbers of the third column, we can easily determine the constants of our equation

$t={\frac {A+B\log v}{A'+B'\log v}}.$