Galvanized Iron

sheet iron coated with zinc. The ordinary commercial article is prepared in the following manner. A sheet of iron is first cleansed with hot sulphuric acid to remove rust and other impurities, and is washed in cold water. It is then plunged into a bath of molten zinc covered with a film of sal ammoniac to prevent its surface from turning into dross. Upon taking out the sheet of iron, it is found to be covered with a coating of zinc, deposited in crystal-like powder, such as may be seen on a frosted window. A more expensive article is prepared by a coating of tin, followed by one of zinc. The plates are treated with sulphuric acid and washed as before. They are then piled in a tank with layers of finely granulated zinc between the plates. The bath is then filled up with a dilute solution of muriate of tin, consisting of about two quarts of the muriate to 300 gallons of water. A sort of galvanic action is set up. At the end of two hours the plates are found to be coated slightly with tin. They are then treated to a zinc bath as before. Galvanized iron is proof against all ordinary attacks of weather. It requires no paint. It is much used for outside walls and roofs, for water pails, and other purposes, eaves, troughs, cistern pipes, smokestacks, furnace jackets, and the like. Bolts used in shipbuilding are galvanized as a protection against rust.