Page:Reflections on the Motive Power of Heat.djvu/81

Rh the water to the original temperature. This can undoubtedly be done by at once putting it again in contact with the body A; but there is then contact between bodies of different temperatures, and loss of motive power. It would be impossible to execute the inverse operation, that is, to return to the body A the caloric employed to raise the temperature of the liquid.

This difficulty may be removed by supposing the difference of temperature between the body A and the body B indefinitely small. The quantity of heat necessary to raise the liquid to its former