Garth, SIR

SAMUEL, M.D., 1660– 1719. Physician to George I.; knighted 1714; author of a satire, The Dispensary, 1699, and other poems. Gärtner's Canal, or DUCT. Rudiment of the Wolffian duct (vas Star, Collar and George, and Garter. deferens) in the female animal. Gas. Aëroform substance po e ing elasticity and indefinite expansibility; it is composed of molecules, in a state of rapid motion in right lines and with the least attraction for each other. It has the form of the ve el containing it, and the impacts of the molecules upon its walls constitute the pre ure of the gas. If it is compre ed, the number of impacts is increased, and thereby the pre ure is increased. The temperature of the gas is the energy of the molecules, so that increase in this also increases the pre ure. The critical temperature of a gas is that temperature above which it cannot be liquefied by increase of pre ure alone and below which such liquefaction may take place. A gas cannot be liquefied at ordinary temperature by pre ure alone, its critical temperature being below this; all the ordinary gases, with the po ible exception of hydrogen, have been liquefied by pre ure and low temperatures. Vapors may be liquefied at ordinary temperature by pre ure, their critical temperatures being above that. Vapors do not conform to the laws of contraction and expansion for compre ion and temperature that apply to gases. See BOYLE'S LAW, CHARLES' LAW, GAY LUSSAC'S LAW, MARRIOTTE'S LAW, DIFFUSION, and EFFUSION.