/euh mal"geuhm/, n.1. an alloy of mercury with another metal or metals.2. an alloy that consists chiefly of silver mixed with mercury and variable amounts of other metals and is used as a dental filling.3. a rare mineral, an alloy of silver and mercury, occurring as silver-white crystals or grains.4. a mixture or combination: His character is a strange amalgam of contradictory traits.[1425-75; late ME amalgam(e) < MF < ML < dial. Ar al the + malgham < Gk málagma softening agent, equiv. to malak- (s. of malássein to soften) + -ma n. suffix]
* * *Those of silver, gold, and palladium occur naturally. Those with a very high mercury content are liquid; others are crystalline. Amalgams of silver and tin, with minor amounts of copper and zinc, are used in dentistry to fill teeth. Sodium amalgam is used in manufacturing chlorine and sodium hydroxide by electrolysis of brine. Amalgams are used to recover silver and gold from their ores: The ore is shaken with mercury, the amalgam is separated and heated until the mercury distills off (see distillation), and the precious metal is the residue. Amalgams are also used to silver mirrors and apply other metal coatings.
* * *▪ alloyalloy of mercury and one or more other metals. Amalgams are crystalline in structure, except for those with a high mercury content, which are liquid. Known since early times, they were mentioned by Pliny the Elder in the 1st century AD. In dentistry, an amalgam of silver and tin, with minor amounts of copper and zinc, is used to fill teeth.A sodium amalgam is formed during the manufacture of chlorine and sodium hydroxide by the electrolysis of brine in cells wherein a stream of mercury constitutes the negative electrode. Reaction of the amalgam with water produces a solution of sodium hydroxide and regenerates the mercury for reuse.Fine particles of silver and gold can be recovered by agitating their ores with mercury and allowing the resultant pasty or liquid amalgam to settle. By distillation of the amalgam, the mercury is reclaimed, and the precious metals are isolated as a residue.Amalgams of silver, gold, and palladium are known in nature. Moschellandsbergite, silver amalgam, is found at Moschellandsberg, Ger.; Sala, Swed.; and Isère, France. Gold amalgam occurs in California, U.S., Colombia, and Borneo. For detailed physical properties of naturally occurring amalgams, see native element (table).
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