Tin is obtained from the ore oxide of tin by smelting. Because of its high price and its low tensile strength (about two tons per square inch), tin is comparatively little used. As one of the constituents of gun-metal or bronze, however, it is of great value. Since it is not acted upon by salts and weak acids in the cold nor by animal or vegetable juices and also since it resists oxidation, tin is often applied to other metals as a protective covering.
In making tin plate, sheet iron is thoroughly cleaned by acid baths, then greased with melted tallow or palm oil to prevent contact with the air, and dipped in a bath of molten tin. A layer of palm oil or other grease also covers the melted tin. After the bath a thin layer of tin sticks to the sheet iron. With this addition the sheet iron is passed through rollers to squeeze off superfluous metal and perfect the coating. This plate is made into tin cans to hold oil, paint, fruit, vegetables, fish, etc. It is also used for roofing and for the manufacture of kitchen utensils.