amalgamArticle Free Pass amalgam, alloy 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