MERCURY is a brilliant white metal, having much of the colour of silver, whence the terms hydrargyrum, argentum vivum, and quicksilver. It has been known from very remote ages. It is liquid at all common temperatures; solid and malleable at 40° - F., and contracts considerably at the moment of congelation. It boils and becomes vapour at about 670°. Its specific gravity at 60° is 13.5. In the solid state its density exceeds 14. The specific gravity of mercurial vapour is 6.976. (Dumas, Ann. de Ch. et Ph. xxxiii. Brande, 928.)

Mercury is used in the fluid state for a variety of philosophical instruments, and for pressure gages for steam engines, etc. It is sometimes, although rarely, employed for rendering alloys more fusible; it is used with tin-foil for silvering looking-glasses, and it has been employed as a substitude: for water in hardening steel. Mercury forms amalgams with bismuth. copper, gold, lead, palladium, silver, tin, and zinc.

Mercury is commonly used for the extraction of gold and silver from their ores by amalgamation, and also in water gilding. See Gold.