The specific gravity of a mineral is its weight compared with some substance taken as a standard. Distilled water is taken as a standard for liquids, air or hydrogen for gases, the weights of bodies being proportional to their masses, therefore the specific gravity of a body is equivalent to its relative density. It is the density or compactness of a substance that gives it its weight, the more compact the heavier. If a mineral weighs twice as much as water, its specific gravity is low, being but two. If three times as heavy, its gravity is three, and so on. To obtain the specific gravity of a mineral, weigh a bit of the same, using a fine balance, then suspend the mineral by a hair or silk thread, or platinum wire, to one of the scales; immerse it, thus suspended, in a glass of distilled water and weigh it again. Subtract the second weight from the first by the difference obtained; the result is the specific gravity. The loss by immersion is equal to a weight of an equal volume of water. The water should be at a temperature of about 60° F.