Iron Amalgam.—Iron will not unite with mercury under ordinary conditions. Small quantities of an iron amalgam have, however, been formed by immersing sodium-amalgam (containing 1 per cent. of sodium) in a clear, saturated solution of ferrous sulphate.
Silver Amalgam.—This compound is formed by the union of mercury with finely-divided silver. Beautiful crystals of native silver amalgam have been found at Moachellandsberg, in the Palatinate, and in several other places. Mercury is used for silver extracting, in a process some what similar to that described above for the extraction of gold.
Sodium Amalgam.—Sodium and mercury combine readily under ordinary conditions by being brought. into contact one with another. The union is attended with much hissing and spluttering, and with a considerable evolution of heat.
Tin Amalgam.—Tiu and mercury combine readily at ordinary temperatures. If three parts of mercury be brought into contact with one part of tin, aix-sided crystals of tin amalgam are formed.
Tin amalgam is used for silvering looking-glasses. When pulverized and rubbed on the polishing stoae it forma a kind of mosaic silver. Electric amalgam may be made by melting tin and zinc together in various proportions in a porcelain crucible. The mixture is well stirred up, and when on the point of solidifying, the mercury is added and worked into the mass. The whole is next transferred to a mortar warm enough to keep the amalgam soft while it is well worked together, after which a piece of tallow or lard, not quite equal in bulk to the mass, is kneaded in until the amalgam attains the proper consistency.
Zinc Amalgam is formed by mixing and triturating zinc filings with mercury, at a heat some what below the boiling point of the latter. It is usually prepared by pouring mercury into zinc at the temperature at which the latter is just kept in a fused state. Care must be taken to keep the liquid stirred, and to add the mercury slowly and in as fine a stream as possible.