Mercury

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…process, in which gold or silver is dissolved in solutions of sodium or potassium cyanide. Mercury is a poisonous element. Mercury is semi hazardous as a vapor and Among the many good things mercury does for people there is a flip side. in the form of its water-soluble salts. Chronic mercury poisoning, which occurs when small amounts of the metal are repeatedly ingested over long periods of time, causes irreversible brain, liver, and kidney damage.