(a) Zinc chloride or sulphate is precipitated by means of a soluble sulphide - sodium, barium, and calcium sulphides have been used - and precautions are taken that no iron present is precipitated. The precipitate is collected, dried, and calcined for some time at cherry-red beat, with careful stirring. It is raked out while hot into vats of cold water, then levigated and dried. It is zinc oxysulphide. (Griffiths.)

(6) A white pigment, said to possesa excellent covering properties, is prepared by bringing together barium sulphide and zinc sulphate in solution, and subjecting the precipitate which ensues (a mixture of zinc sulphide and baryta sulphate) to the action of superheated steam, by which, at white heat, all the zinc sulphide will be converted into zinc oxide. (Meissner.)

(c) Crude barium sulphide is lixiviated. The supernatant liquid is drawn off, and divided into equal portions. To one, an equivalent of zinc chloride is added, and to this again zinc sulphate, and afterwards another portion of barium sulphide, the result being an intimate mixture of 1 equivalent of barium sulphate and 2 of zinc sulphide. The precipitates, com posed of zinc and barium, are collected, pressed to expedite drying, placed in a retort, and brought to a red heat. While still hot, they are drawn into water, preferably cold, which, it seems, has the effect of increasing their density, and imparting body to the paint to he made from them. They are subsequently washed and ground in water to fine powder, or first dried and then ground. By increasing the number of additions of zinc sulphate, the quality may be varied. The pigment thus prepared is used in the ordinary way. (Orr.)

(d) Zinc-dust, containing lead, silver, copper, and other impurities, is allowed to digest in leaden vessels filled with a concentrated solution of ammonium carbonate in ammonia water. The amnion iacal zinc solution thus obtained is freed from copper by precipitation with a further small quantity of zinc, decanted off, and submitted to distillation, whereby the ammonia is recovered, and in the retort is found zinc carbonate, which by ignition may be converted into oxide. The residual oxides containing silver and lead may either be treated by the refinery process for the separation of silver, or are washed, dried, ignited to drive off any carbonic acid, and treated with a warm solution of lead acetate. This dissolves the lead oxide present, with formation of a basic acetate, from which lead carbonate is precipitated by treatment with carbonic acid gas. (Schnabel.)