One method is to dissolve the scrap gold in a mixture of 1 part pure nitric acid, 3 parts hydrochloric acid, and 1 part pure water made warm in a porcelain basin and placed in a good draught to carry off the poisonous fumes. Drive off excess acid by heat, dissolve the resulting red salt in pure water, and carefully decant or filter to remove silver chloride. Add a solution of protosulphate of iron until all gold is thrown down as a brown powder. Decant off all iron and copper solution. Well wash the gold several times in hot water, and dissolve to form the gilding bath, or dry and fuse with borax in a fireclay crucible. Another method is to melt scrap with twelve times its weight of pure lead on a large bone ash cupel and keep up the heat in the open air until all copper and other base metals have been oxidised. Then fuse the button of gold with two and a half times its weight of pure silver, and dissolve out all silver in warm nitric acid.