be seriously delayed. The metal is almost as resistant as gold to the action of air and water, and to the attacks of those acids which exist in foods of all kinds, and which in a few weeks would destroy iron, and convert copper, lead or zinc into poisons, and kindly nature has segregated it in the crust of the earth in places where it may be collected at moderate cost, and utilized in activities that have become quite of the nature of indispensables to the further progress of humanity.
Zinc
This metal, which a thousand years ago was a puzzle to the metallurgists, and a nuisance to the lead miner, has become, during the last quarter of a century, one of the most useful and necessary products of the mine. The demand has increased so enormously that producers have at times had the greatest difficulty in meeting it. We have no reliable statistics of the world's output previous to 1883, when it amounted to 310,000 tons. Its principal use up to that date was for the production of brass, an indispensable alloy in the manufacture of bearings and fittings for all kinds of machinery. Previous to the present mechanical age its only use was in ornamentation. Now many other employments have been found for the metal. In the condition of an oxide it is consumed very extensively by the paint manufacturers. In the form of an electrically deposited coating on sheet iron it is in great demand by the building trade for cornice work, etc., under the name of galvanized iron, and is exported in enormous quantities to all new parts of the world for use as roofing and siding in those temporary structures reared for protection against the weather in lands where lumber is not available at reasonable cost. With the development of the electrical industries it has become a necessity in many forms of batteries, and during the last dozen years or so hundreds of tons have been consumed annually in the recovery of gold from certain of its ores by means of what is known as the cyanide process. These new uses, as well as the steady increase in the demand for brass in the ever-growing machinery trade, have caused its production to grow with such rapidity that in 1906 the crop amounted to 774,525 tons, a gain of 250 per cent, in twenty-four years. Zinc is not reckoned as one of the heavy metals, nor yet is it a light one, its specific gravity being a little less than that of iron. Yet if the product of last year was melted and cast into a pyramid with a base of an acre, the apex would stand at an altitude of about 250 feet. This is a fairly good record for a metal that in 1850 was practically unused except in the form of brass. By itself, it is a beautiful substance, almost as soft as lead, very malleable, and with a rich blue-white luster that is the delight of the artist.
History seems to indicate very clearly that nations who have pos-
