very fine parts. When it is to be applied to a body that is of metal, the surface is previously covered with some gluey substance or size; and when the body is to be exposed to the injuries of the weather, a composition of drying oil and yellow ochre is used in place of the water-size.

In the process of gilding metals, the surface is first cleansed, and then the leaves applied, which, by means of rubbing with a polished blood-stone, and a certain degree of heat, are made to adhere in the manner desired. Gold is also sometimes fixed on metals, by previously reducing it into an amalgam or paste, with mercury. With this amalgam, the metal to be gilded is covered; and, on the application of heat sufficient to evaporate the mercury, nothing is left but the gold, which is afterward burnished with a blood-stone. Another method of gilding metal, is by the application of gold dissolved in aqua-regia.

Gold is also applied to glass, porcelain, and other vitrified substances, of which the surfaces, being very smooth, are capable of perfect contact with the gold-leaves. This gilding is so much the more excellent as the gold is more exactly applied, which done, the articles are exposed to a certain degree of heat, and afterward slightly burnished; or a more substantial gilding is fixed upon glass by the use of powder of gold mixed with a solution of gum-arabic, or with some essential oil, and a small quantity of borax.

Gin. See GENEVA.

Gin, in mechanics (a word contracted from engine), a machine for driving piles; or a trap.

GINGER, in botany, an aromatic root, cultivated at

7 VOL. III.

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