HEAT

This term has been applied b-JiI\ to the sensation experienced on touching a hot body, and n \\e cause of that sensation: in the latter sense it is synonym >w* with the term caloric. The cause of the phenomena of hoat is unknown; but they are supposed to depend upon the p-esence of a highly attenuated, imponderable, and subtile faoi of matter, the particles of which repel each other, but ar.i. ttracted by other bodies. The escape of heat through sp.xe is called the radiation of hent, and its communication 'jy contact conduction. The term specific heat is applied to the quantity of thermometric heat required to raise different substances to the same temperature. Thus experiments prove that the quantity of heat which will raise olive oil two degrees will only raise water one degree; hence a pound of water at 212° may be said to contain twice as much heat, or to have twice the capacity for heat that belongs to oil: or the specific heat of water being =1, that of oil is 05. When heat changes the state or form of bodies a large quantity disappears, and remains in them so long as they retain one form. To heat in this state of combination, and inappreciable by the thermometer, the term latent heat or caloric of fluidity has been applied. See Expansion, Evaporation, . HEATH, or [s. 562]