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Gravity (SPECIFIC in physics)

SPECIFIC, in physics, the relative density of a substance; the weight of a body compared with that of another body having the same magnitude. To obtain this, it is first another body having the same magniin air, which shows its absolute weight. Next it is weighed in water, to show how much it loses in this element. There have now been ascertained the absolute weights of two bodies of equal bulk-viz., the one experimented on, and water, and the ratio of these weights is that also of their specific gravities. Let 1 be the weight of water, and first let the body be heavier than that liquid, then the weight which it loses in water is to the absolute weight as 1 to the specific grav- If lighter than water, ity required. then as the weight of the body in air, plus the weight needful to make it sink in water, is to its weight in air, so is 1 to the specific gravity. On this principle are constructed such instruments as Nicholson's portable balance. In solids and liquids the standard is generally distilled water; for the gases, atmospheric air. Specific gravity is proportionate to density, and the words may be used almost interchangeably.