SPECIFIC GRAVITY of any body is the proportion which the weight of a certain billie of that body bears to the same bulk of another body, Which is taken as a standard. The standard for substances solid and liquid is distilled water at the temperature of 62° Fah., barometer 30 inches; and the weight of a cubic inch of this standard is given in the Parliamentary Reports for 1825 as 232.456 troy grains, hence a cubic foot of it weighs 997.129 avoirdupois ounces, or 62.82 avoirdupois pounds. It is convenient to remember that a cubic foot of water weighs about 1000 ounces avoirdupois, as the error result ing from employing this estimate does not amount to much more than of thcf whole. For atiriform bodies, the standard is atmospheric air, a cubic inch of which, at a temperature of 32° Fahr., weighs • 32695, and at 60' Fahr., • 30983 grains troy. The specific gravity of solid bodies is best measured by the hydrostatic balance—a figure of which is given under Archimedes, Principle of (q.v.)--which gives the weight of a volume of
water equal in bulk to the solid, by which it is only necessary to divide the weight of the solid in air to obtain the specific gravity; that of liquids may be obtained by the are ometer (q.v.), or by comparing the weight lost by a solid body in the liquid and in water, and dividing the former by the latter—or by means of the specific-gravity bottle, which holds exactly 1000 grains of distilled water in its standard condition. The bottle is emptied of water, hided with the liquid, and then weighed; the result gives the weight of a volume of the fluid equal in bulk to 1000 grains of the standard, and hence this weight divided by 1000 gives the specific gravity. The specific gravity of all Oxiform fluia is determined by weighing a glass globe filled first. with the fluid and then with atmospheric air. Annexed is a table of the specific gravity of a few of the more com mon substances: