Zinc The origin of the art of smelting is lost in the mists of antiquity. Brass was an article of commerce with the Orient from the earliest days of which there is record, but brass can be made by the 'cementation' process in which granulated copper is melted with granulated 'calamine' (oxidized zinc ore), and hence the existence of brass is not proof of the production of metallic zinc. How es cr. metallic zinc was certainly known in India in the 14th century. Zinc ore may be reduced by burning off the zinc as oxide, the os.,le ma. lie utilized such or may he dissulsed and the zinc content deposited electrolytically; or the desulphurized ore may be leached with sulphuric or other acid and the zinc obtained by electrolysis. Both these methods are in commercial use, and other electrochemical processes are in a fair way to be established. Electrothermic reduction of zinc ores is practised in Sweden, but has not yet proved commercially feasible in the United States. The low volatilization point of zinc led to distillation as the first method for the reduction of zinc ores, and it is yet the chief In 1913 the United States ranked first in production, with 31.7 per cent, and first in con sumption, with 27.7 per cent. The other large consumers were Germany, 22.9 per cent; Great Britain, 192 per cent ; France, 8.1 per cent, and Belgium, 7.5 per cent.
The production and consumption of metallic zinc in the United States during the European War as compared to the average of the four years immediately preceding the war is here shown, in short tons.
method. The native Chinese method of making i zinc, though primitive, nevertheless, involves all the essential principles of modern zinc dis tillation. Clay pots or crucibles are set in the flat top of the furnace so that the lower half is exposed to the heat of the furnace. The zinc ore and carbon are put into the pot, a sloping partition with a perforation at the upper edge is luted (sealed with clay) into position at the middle of the pot, and the cover is lutcd on. The zinc vapor comes up through the perforation, condenses in the cooler upper chamber and collects as liquid zinc on the lower portion of the sloping partition, whence it may be dipped and cast into cakes. In the modern retort furnace there may be 300 to 450 clay retorts set in three to five horizontal rows, each retort about 10 inches in diameter and about five feet long. Two such furnace.: are
joined back to back in a block. Only the mouth of the retort projects from the furnace, and to this is luted the condenser, a conical clay cylinder closed at the slightly lower front end, except for a small aperture, by a clay plug. The zinc vapor distils over and is liquefied in the condenser, from which it is •drawn' and cast into slabs four times during the 'campaign' which lasts 24 hours, the re torts being cleaned out and the charges re newed each morning.
World's production of metal lic zinc in 1913. in short tons was a follows: The first zinc was made in the United States in 1835 by Dr. F. R. Hassler, superintendent of the United States Coast Survey. Finding it impossible to obtain abroad brass or zinc of the requisite purity for the standard sets of weights and measures he set up a small zinc distillation plant in the arsenal at Washington. The ore used was a mixture of blende from Perkiomen, Pa., and red zinc ore from Franklin N Furnace, ew Jersey. The first zinc smelting on a commercial scale was at the Lehigh works at South Bethlehem, Pa., in 1860. In the same year the Matthiessen and Hegeler works were opened at La Salle, III. These were the main eastern and western centres of zinc smelting until 1892, when smelters in the coal fields of Kansas assumed equal importance with Illinois plants. This importance was increased about 18%, when natural gas began to he used for smelting, and by 1899 Kansas had become the largest producer among the States. The waning of the gas fields caused Kansas to fall behind Illinois in 1913, but for the last two years the natural-gas smelters of Oklahoma. which first smelted zinc in 1907, have held that State in the front rank. (See Eurraocnsmicm. Ix DUSTIIES ; METALLURGY; METALS). Consult Hol ley. C. D., 'Lead and Zinc Pigments' (New York 1909) ; Ingalls, W. R., 'Production and Properties of Zinc' (ib. 19(Q); id„ 'Metallurgy of Zinc and Cadmium' (2d ed, ib. 1906): id., 'Lead and Zinc in the United States' (ib 1908); 'Mineral Industry' (annual vol„ Ncw York) ; 'Mineral Resources of the t'ntted States' (annual vol., United States Geological Survey, Washington, D. C.).