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Chloride of Gold

Gold unites with chlorine under two different proportions, and are distinguished as the protochloride and the terchloride of gold.

The terchloride of gold, or auric chloride, parts nitrate of silver, and 1 part hydrate of Oxide of Silver. Dissolve 2 potassa, each separately, in distilled water; mix the solution, and, after frequent agitation during an hour, collect and wash the precipitate, and dry it by a gentle heat in the shade. This is more strictly the protoxide of silver, and is in the form of a pale brown powder.

4079. Το Reduce Solid Silver from of silver in 1/80 its weight of powdered black its Chloride. Mix together the dry chloride resin; heat moderately in a crucible until the flame ceases to have a greenish blue color; ver fuses into a button at the bottom of the then increase the heat suddenly until the silconsists of 3 equivalents of chlorine and 1 of crucible. Some parties recommend an adgold, and is obtained by dissolving 1 part gold dition of a little powdered calcined borax, in 3 parts nitro-muriatic acid (aqua-regia); sprinkled on the surface before increasing the evaporate until vapors of chlorine begin to heat. (See No. 3214.) be disengaged, and then set the solution aside to crystallize. It forms orange-red from an Alloy of Silver and Copper. crystalline needles, or ruby-red prismatic crys- Palm's method. When it is desired to pretals; is deliquescent, and soluble in water , pare nitrate of silver from silver containing other, and alcohol, forming a deep yellow solu- copper-coins for example-filter the nitric tion. (Cooley.)

4080. To Prepare Nitrate of Silver The protochloride of gold, or aurous chlor- evaporate it nearly to the consistence of oil,. acid solution, dissolve the alloy in nitric acid, ide, consists of 1 equivalent each of chlorine not to dryness, and add to a part of this con- , consists of 1 equivalent each of chlorine not to dryness, and add to a part of this conand gold, and is obtained by evaporating the centrated metallic solution, part of nitric terchloride to dryness and exposing it to a acid free from chlorine. The silver salt preheat of 450° (440° Fownes) Fahr ., until cipitates in the form of crystals and the copchlorine ceases to be evolved. It forms a per remains in the solution. Wash the preyellowish-white mass, insoluble in water; but cipitate 2 or 3 times with concentrated nitric it is decomposed by water, slowly when cold, acid, and evaporate to dryness. The more and rapidly by the aid of heat, into metallic concentrated the nitric acid, the more comgold and terchloride of gold. (Cooley.) pletely is the silver salt precipitated; an acid . of 1.250 specific gravity is sufficient, however, tates in solutions previously acidulated with to separate completely the two metals. (See hydrochloric acid. (Cooley). No. 3216.)