AMALGAMATION

AMALGAMATION, in Chemistry, the Operation of making an Amalgama; i.e., of calcining, or rather dissolving some Metal, especially Gold, by means of Mercury. See AMALGAMA. Amalgamation is performed by fusing, or at least igniting the Metal; and in this State adding a proportion of Mercury thereto; upon which they mutually attract, and incorporate with each other. See MERCURY. All Metals, except Iron and Copper, unite and amalgamate with Mercury; but Gold with the greatest facility; Silver the next; then Lead, and Tin. See METAL, etc. The Amalgamation of Gold is usually performed by heating the Laminae or Plates of Metal red hot; after which, Quick-silver is to be poured upon them, and the Mixture stirred with a little Iron Rod, till it begins to rise into Smoke.—It is then thrown into a Vessel full of Water, where it coagulates and becomes manageable. This Calcination is in great use among Goldsmiths, and Gilders, who by this means render Gold fluid and ductile for their Purposes—Such Mixture or Amalgama being laid on any other Metal, for instance, Copper; and this afterwards placed on the Fire to evaporate; the Gold will be left alone on the Surface of the Copper: which makes what we call Gilding. See GILDING. The Blackness adhering to the Amalgam may be washed away with Water; and a deal of the Mercury pressed out through a linen Cloth: The rest being evaporated in a Crucible, the Gold remains behind in an impalpable Powder. See GOLD. Gold retains about thrice its own weight of Mercury. This Operation is denoted among Chemists by the Letters AAA. See CHARACTER.