To make cyanide of gold for electro-plating, disso've 1 oz. of oure gold in aqua regia (a mixture of hydrochloric and nitric acids), evaporate to dryness, dissolve the residue in 15 pt. of water, and add 5 1/4oz. of cyanide of potash. Chloride of gold may be used, but about 1 1/2oz. would be required. The amount of cyanide of potash may be varied.