The principal uses for this metal are as follows:

(1) The most important use is for alloying with copper in making brass or composition.

(2) When zinc is exposed to air or water, a durable and impermeable coating of zinc carbonate is formed on the surface of the metal. This makes it useful for galvanizing iron to protect against rusting. Zinc sheets may be used for sheathing or roofing.

(3) Zinc is the most electro-positive of the common metals. This makes it particularly useful as a protection against galvanic corrosion in steam boilers, and on the hulls of steel ships. Copper, brass and bronze may also be protected by its use. Rolled zinc slabs are bolted in scraped metallic contact with the part to be protected, and the electrolytic action of impure water in which the metals are immersed gradually corrodes the zinc, leaving the protected metal intact. However, when the zinc becomes much corroded and its metallic surface is no longer exposed, the zinc compound resulting from the corrosion acts electro-negative to the protected metal and this metal is itself destroyed. The protection of iron by galvanizing, as mentioned in item (2), is due not only to a coating of zinc but to the fact that when a part of the zinc coating is broken and the iron is exposed, dampness sets up an electric current which consumes the zinc instead of the iron.

(4) Zinc plates are used extensively in electric batteries.

(5) Oxide and sulphide of zinc are used to make a superior grade of white paint.