Important: Safety Warning
This page describes trade processes that use dangerously toxic materials such as cyanide solutions, mercury amalgams, or strong acids. These processes require training, equipment, and precautions far beyond what the text describes.
This information has been left in for historical purposes but should not be acted upon.
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To Purify Platinum
The native alloy (crude platinum) is acted upon, as far as possible, with nitro-muriatic acid, containing an excess of muriatic acid, and slightly diluted with water. The solution is precipitated by the addition of sal-ammoniac, which throws down nearly the whole of the An ntimony. This is a bluish-white, lustrous, semi-crystalline, extremely brittle metal, of about 6.7 specific gravity; imparts brittleness to alloys; inflammable at high temperature; melts just under redness, 8100 Fahr., fumes, boils, and volatilizes at a white heat, and when suddenly exposed to the air, inflames and is converted into teroxide platinum in the state of an ammonio-chloride, of antimony, which is deposited in beautiful which is washed with a little cold water, dried, and heated to redness; the product is spongy metallic platinum. This is made into a thin uniform paste with water, pressed in a brass mould, to squeeze out the water and render the mass sufficiently solid to bear handling. It is then dried, carefully heated to whiteness, and hammered or pressed in the heated state; after this treatment it may be rolled into plates or worked into any desired shape. (Cooley).