See Plate Powder. To clean silver utensils, blackeued by sulphuretted hydrogen, Bottger recommends a boiling saturated solution of borax, or a solution of caustic potash, with some fragments of metallic zinc.

Silvering Powder, &e.,for silvering copper, covering the worn parts of plated goods, etc. 1. Nitrate of silver 30 grs., common salt 30 grs., cream of tartar 3 1/2 drs. Mix.

[ Moistened with water and rubbed on dial plates or other copper articles, it coats them with silver.

2. Silver precipitated from its nitric solution by copper 20 grs., alum 30 grs., cream of tartar 2 drs., salt 2 drs.

3. Precipitated silver 1/2 oz. common salt 2 oz., chloride of ammonium 2 oz., corrosive sublimate 1 dr.; make it into a paste with water. Copper utensils are previously boiled with tartar and alum, and rubbed with this paste, then made red-hot, and afterwards polished.

4. Dissolve chloride of silver in a solution of hyposulphite of soda, and mix this with prepared hartshorn or other suitable powder.