ZINC AND ITS ALLOYS Zine.—Zinc, sometimes called spel ter, is almost as common as lead. It has the peculiarity of evaporating, like water, at a comparatively low temperature. Hence it is produced by a process of distillation. The ores are heated in retorts, and the zinc vapor is carried off condensed and purified through suitable pipes. Zinc is very hard, of a bluish color, and when fresh of a brilliant luster. It tarnishes by contact with the air, forming a thin, hard film which pro tects it from further oxidation. Hence zinc is very durable and resists both air and water. Iron and other metals are often protected by a coating or an impervious varnish of zinc, form ing galvanized iron, which does not rust until the zinc has worn away.
Zinc is crystalline and brittle at ordinary temperatures, but at a tem perature of 300° F. it may be rolled into thin plates, and is quite malleable. At 400° it may be crushed to powder, at 780° it melts, and boils at 1900°, giving off a vapor which takes fire if exposed to the air, and burns with a bright light to zinc oxide. This is a pigment used as a commercial product instead of white lead for painting woodwork. Pure zinc dis solves in nitric acid, but not in dilute sulphuric acid or hydrochloric acid.
Contact with other metals and sub stances capable of conducting electric ity sets up 71. voltaic circuit of elec tricity which dissolves the zinc. This is seen in voltaic batteries; hence commercial zinc, containing more or less lead, iron, etc., may be dissolved readily in acids, alkalies, and even in neutral solutions on account of the electric circuits set up between the zinc and the other metals with which it is alloyed.
Alloys of Zinc.—The principal al loys of zinc are given under copper, brass, and bronze. Zinc alloys readily with all the common metals, except lead and bismuth. These alloys par take of the hardness of zinc, and also, when used in excess, of its brittleness. The most important use of zinc as an alloy is in the manufacture of brass. Zinc will not unite with lead except in the presence of tin or other metal. With lead and bismuth it forms a fusible alloy which melts in boiling water. Zinc is sometimes used to al loy bronze, which should properly consist only of tin and copper. The triple alloy of these three metals is used for journal boxes and other pur poses where great hardness is desired. An amalgam of zinc with mercury is used for coating voltaic batteries Other alloys of zinc are: White metal, 1 zinc; 1 tin, and a little antimony.
Antifriction alloy, 17 zinc; 9 tin; I antimony. This can be used for linings or for castings instead of brass.
Imitation of German silver, 85 zinc; 15 copper.
Substitute bronze, copper, and brass, 90 zinc; 8 copper; 1 cast iron; 1 lead.
Or 91 zinc; 8 copper; 1 lead. These alloys may be colored to represent any alloy.
Equal parts of zinc and tin make an alloy almost as strong as brass.
Zinc Solder.—Common solder, 1 tin and 1 lead. Or coarse solder, 2 lead and 1 tin, will solder zinc. Wet the parts with the liquid and sprinkle with powdered borax.