The proportions of the bath are as follows: - Distilled water, 66 gal.; soda pyrophosphate, 11 lb.; fused tin protochloride, 35 oz. A thin tinning is obtained by simple dipping, and one of any thickness by the aid of the battery.
Zinc is deposited by the wet way and by the battery. The dead lustre colour is a grey blueish-white. Precipitate a soluble zinc salt by ammnoia; this precipitate re4issolve4 in an excess of alkali gives a satisfactory bath; any kind of zinc salt may also be dissolved in potassium cyanide or a soluble sulphite. These deposits are entirely different as regards the durability, from the so-called galvanising, when cleansed iron is plunged into a bath of molten zinc, and is thus protected against oxidation for a long time, which is not the case with electro-deposited zinc.
For depositing upon copper or brass, in the wet way, prepare finely-divided zinc, by pouring the molten metal into a previously strongly heated iron mortar, and stirring until nearly cold. The powdered zinc thus obtained is placed in a porcelain vessel, and to it is added a concentrated solution of sal ammoniac. This mixture is heated to boiling; and the copper or brass objects to be coated with zinc, but previously well cleansed, even with an acid, are then placed in a liquid where they obtain a brilliantly white adhering layer of zinc.