11,103. Boult, A. J., [Fl³gger, E.]. May 8. Zinc oxide and sulphide; sodium and potassiumzincates.-Sodium or potassium zincate is prepared in a pure condition for the production of zinc oxide and sulphide. The zincate is purified by treatment with zinc dust in quantity less than enough to chemically replace the foreign metals present, or the solution is prepared under specified conditions of concentration and time of heating which exclude foreign metals. From the pure zincate, zinc oxide is obtained by precipitation with water above 80‹ C. or by heating to 100‹ C. in vacuo the hydrated precipitate obtained at lower temperatures, while zinc sulphide is obtained by precipitating the solution with hydrogen or other soluble sulphide, and lithopone by precipitating with barium sulphide in presence of sulphuric acid or a soluble sulphate, or by mixing the sulphide precipitate with barium sulphate. The zincate solution may be prepared from scrap zinc or galvanized iron, the alkali being used until more than half of it is combined with zinc.