| VP = vP′; |
and by formula (6.) we have
| V′ | = | 1 + n(T′ − 32) |
| v | 1 + n(T − 32) |
Eliminating v, we shall obtain
| V | = | P′ | · | 1 + n(T − 32) | ; |
| V′ | P | 1 + n(T′ − 32) |
or,
| VP | = | 1 + n(T − 32) | ;(8.) |
| V′P′ | 1 + n(T′ − 32) |
which is the general relation between the volumes, pressures, and temperatures of the same gas or vapour in two different states.
To apply this general formula to the case of the vapour of water, let T′ = 212°. It is known by experiment that the corresponding value of P′, expressed in pounds per square inch, is 14·706; and that V′, expressed in cubic inches, the water evaporated being taken as a cubic inch, is 1700. If, then, we take 0·002083 as the value of n, we shall have by (8.),