Manufacture of Zinc White.

The Journal of the Board of Arts and Manufactures for Upper Canada, July 1867

Zinc-white may be prepared from any zinc ores or old zinc by roasting the same for the purpose of producing the oxyd and treating the latter with a hot solution of muriate of ammonia, which dissolves the oxyd of zinc, while other metals contained in the ore remain behind If the solution is coloured the addition of a small quantity of carbonate of soda will cause a slight precipitate, when the solution will appear clear. The solution is then filtered, when upon cooling the oxyd precipitates, together with a double salt of ammonia and zinc but slightly soluble in cold water. This precipitate is washed, treated with hot water, when the double salt becomes decomposed and the oxyd of zinc is precipitated as a dense white powder, which is washed and dried.