products will satisfactorily explain. A more careful examination into the methods of manufacture at the different works, and inquiry into the general results obtained, are apt to leave the impression that the whole subject is enveloped in mystery, belonging more properly to a secret art in the Middle Ages than to a growing industry of the present century. Every year or two some European expert makes a rapid tour through the country, and announces that our ores are "equal to the best in Europe, but that our methods of mining and preparing them are extremely wasteful, and our methods of smelting are crude and extravagant, and fully a generation behind European practice in technical value and economy." It cannot be denied that there is much justice in these criticisms; nor is a comparison any more favorable to this country, if we regard only the magnitude of our output or the cheapness of our products.

This inferiority cannot be excused on the ground that the art of mining or that of zinc smelting are still in their infancy in this country, but it can be explained in part, first, by certain general limitations to improvement imposed by the nature of the operations necessarily involved in the smelting of zinc, and second, by the peculiar condition of our ore supply. In its essential features the metallurgy of zinc is the same all over the world. The metal must be distilled in fire-clay vessels, in the presence of carbon, and condensed out of the reach of oxidizing agents. The dimensions of the distilling vessels are restricted within very narrow limits, by the nature of refractory materials and the thickness of the charge through which the necessary heat to effect reduction can be economically transmitted, and but little improvement is to be hoped for by a change in these dimensions. The operations to which the ore and products must be submitted are numerous, and the repeated handling of them cannot be avoided. The recent improvements in European practice have not been the results of changes in the form of the furnaces, or in the methods of treating the ore, but have resulted from careful economies in the use of labor, fuel, and ore, and have only kept pace with the concentration of mining and smelting industries into the hands of strong companies, and are in general such as can only be introduced by companies with abundant capital, and where operations of a certain magnitude are carried on. Moreover, the policy of these companies has been, by regulating the output of the mines and the disposition of the metal, to give a steadiness to the value of both the metal and the ores, which has rendered comparatively safe such investments of capital as would otherwise have been precarious.

Such a condition of affairs can only be gradually brought about in this country, owing largely to the circumstances under which existing works were established, and to the peculiarities of the ore supply. The conditions under which smelting is carried on at the different works in this country are so various that only a general description of them is practicable; and the question of ore supply is so important that it merits

more than a passing notice. The greater part of the ore used in this country is obtained as a more or less valuable by-product in the mining of lead ore; and its selling price is not controlled, either by the value of the metal it contains, or by the cost of its discovery and mining. Hence its value is subject to sudden changes, and the investment of capital in zinc mining is rendered more or less unsafe. This fact has exerted a controlling influence on the methods of mining and selling the ore, on the districts most extensively worked, on the location of the principal smelting works, and on their policy towards the ore producers, and its effects will probably long continue to be felt on the zinc industries of the country. Its full importance may perhaps be obscured by the fact that lead and zinc ores are almost universally found associated together; but where the selling price of both ores is controlled by the value of the metal they contain, each bears its proper proportion of the cost of mining, and neither unduly depreciates the value of the other. The inland location of existing mines and works in this country, as compared with the mines and works of Europe, makes them more dependent on railroad transportation and less easily adaptable to changes in the mining and smelting centers. The metallurgy of lead is so simple that when rich deposits of lead and zinc ore are discovered the lead ores are quickly made available by furnaces erected to treat them, and are mined extensively; while large amounts of zinc ore are often neglected or thrown aside as worthless. The metallurgy of zinc is so complicated and expensive that it is slow to adapt itself to new localities, and the works within reach of the new ore fields have a practical monopoly of these markets.

Sources of supply. The present sources of ore supply may be grouped under three divisions: the Eastern, including New Jersey, Pennsylvania, and Virginia; the Middle, including Wisconsin, Illinois, and Tennessee; and the Western, including Missouri and Kansas. These divisions correspond very nearly with distinct types of furnaces and different systems of mining; and may conveniently be treated of separately.

EASTERN DIVISION.

New Jersey. In the Eastern division, the most notable deposit of zinc ore is in Sussex county, New Jersey, where, near the town of Franklin, there is found an absolutely unique deposit of the three rare minerals zincite (red oxide of zinc), willemite (anhydrous silicate of zinc), and franklinite, forming a rock-like mass not unlike in appearance an eruption of granite, in which the franklinite represents the quartz, the willemite the feldspar, and the zincite the mica. This mass fills the space between limestone walls, and is crossed by numerous "trap" dikes, ranging from a fraction of an inch in thickness up to 20 feet; and is interspersed with occasional bunches of calcite, fowlerite, and other crystalline minerals. The principal mine is on Mine hill. The ore is

reached by a tunnel about 75 feet below the outcrop, and has a width of from 40 to 50 feet. It appears to be a chimney-like deposit, of the form so common in magnetite mines; no limit to it has yet been found in depth or in horizontal extension. This deposit, which has been the subject of numerous long and expensive litigations, is now controlled and worked by the New Jersey Zinc and Iron Company, with a capital of $3,000,000, which in 1880 consolidated rival claims. The ore is easily mined and requires little selection. The cost of mining and putting it on cars should not exceed the cost of quarrying an equal amount of limestone. An average sample would contain about 36 per cent. oxide of zinc, 22 per cent. metallic iron, and 11 per cent. metallic manganese. Owing to its low percentage of zinc and high percentage of iron and manganese, this ore is unsuitable for the manufacture of spelter. The mechanical separation of the zinc ores has been found impracticable on account of the intimate chemical and mechanical mixture of the different ingredients. The ore is, however, particularly adapted for the manufacture of oxide of zinc, or "zine white," for which purpose it is exclusively used. The works of this company are at Newark, New Jersey, at which point they have excellent facilities for obtaining a cheap supply of pea and slack anthracite coal, and direct communication with the mine by canal and railroad.

A smaller vein on Mine hill, called the "front vein," has been proved for several hundred yards; it varies from 8 to 20 feet in width, and is occasionally pinched out by the wall rocks; it carries a less proportion of zincite and a greater proportion of calcite than the large vein, but its ores are of a similar character. Part of this vein is owned by the above-named company, and part is at present furnishing ore to the Lehigh Zinc Works, at Bethlehem, Pennsylvania.

Similar veins are found at Sterling Hill, about 2 miles distant, and have been worked to a depth of about 200 feet by the New Jersey Zinc Company, now incorporated with the New Jersey Zinc and Iron Company, and by the Passaic Zinc Company. On the property of the latter company they are accompanied by irregular beds of beautifully crystallized calamine, from which, as it is almost entirely free from lead, a high grade of spelter is made at the works of the company at Jersey City. Mining at this point has been almost entirely suspended during the last few years, as the Passaic Company has had a contract for ore from the large vein on Mine hill.

The shipments of zinc ore from this county for the year 1882 are reported by the State geologist to have been 40,138 tons; and the total output up to the present time can safely be stated at upwards of 250,000 gross tons.

Pennsylvania.-The zinc deposits in the Saucon valley, Lehigh county, Pennsylvania, which were once extensively worked, now produce but little ore. Their history, however, has a special interest from their connection with the introduction of spelter-making into this country, and

from the fact that they belong to a class of deposits which seems to warrant a belief in their continuance to a considerable depth, and because they are a good illustration of the general effect of the characteristic feature of the ore market, above referred to. Three principal deposits have been discovered, known respectively as the Ueberoth, Hartman, and Saucon mines; they occur in magnesian limestone of the Lower Silurian formation, and have many points in common, while they also present some striking differences. They were all at one time owned or controlled by the Lehigh Zinc Company, whose works were at Bethlehem, four miles distant. The Ueberoth mine, which is, so far as de velopments have shown, the largest, was worked. continuously from 1853 up to the fall of 1876. It was for many years the main dependence of these works, and produced in the neighborhood of 300,000 tons of ore. The strata of limestone are here very much disturbed and tilted up almost to the vertical, apparently by the obtrusion of the syenite ridge of the neighboring South mountain. The ore came close to the surface, and a very rich pocket was found in the clay above and around limestone bowlders, which is estimated to have produced 100,000 tons of ore. When this body of ore was exhausted, the ore was followed down in crevices between the bowlders. These crevices lie in planes parallel to the bedding of the limestone, or in planes perpendicular to it, and preserve great regularity in their position, and a parallel course for several hundred yards in a northeast and southwest direction; they are nearly vertical, and at the depth of 225 feet, to which the mine was worked, showed no signs of closing up. The ores at first were exclusively calamine and smithsonite, but at greater depth blende made its appearance, coating the walls of the crevices, and in some cases penetrating into them several feet; in other cases segregated as rich seams, which nearly filled the cross openings. At first it was confined to the northeastern end of the mine, but at the lowest depth reached it could be traced almost continuously to the extreme southwestern end. The dip of the ore body appeared to be regular, and to the southwest. Six of these parallel crevices were worked, and about as many crossings; and where they intersected rich bunches of ore were found, some of which were as much as 60 feet across and 20 feet thick. All the indications seemed to point with increasing certainty to the existence of a backbone or underlying deposit of blende, out of the reach of the action of meteoric waters, from the continuation of which the oxidized ores have been derived. Timbering the mine was always a serious difficulty, but the greatest obstacle to be overcome was the water. Even at a depth of 40 feet the flow was already very strong; at the depth of 150 feet it was found necessary to put in what was then the largest pumping engine in the world. This engine, which is a single cylinder, double acting, condensing, walking beam engine, with a pair of flywheels, has a 110 inch cylinder and a 10-foot stroke, and is calculated to work four 30-inch plunger pumps and four 30-inch lift pumps, with 10-foot stroke, and to take

water from a depth of 300 feet. At the time it was stopped it was running from six to seven strokes a minute, and was working three pairs of 30-inch pumps and one pair of 22-inch pumps, and was easily handling all the water that came to them. The pump shaft and foundation for the engine were no less remarkable in their way. The latter was built up from the solid rock, 60 feet below the surface of the ground, of hewn blocks of Potsdam sandstone; the former, which measured 30 feet by 20 feet in the clear, was started on a small crevice, and timbered with 12-inch square yellow pine sticks, and divided into three compartments, and further strengthened by two open brattices of the same heavy timber. When the pitch of the vein carried it out of the shaft the rest of the depth was sunk through solid rock.

The Hartman mine, distant about half a mile, was worked at first exclusively for calamine. Its exploitation gradually exposed a central "horse" of blende, which the method of mining adopted made it necessary to leave for the support of the timbers which carried the roof. The increasing importance of this blende at the lowest level worked, 150 feet, caused a change to be made in the methods of mining. The mine was operated for a year after the large engine was stopped, and the last work that was done was the putting in of a slope to develop this deposit of blende. The water in the Hartman was always less strong, the pitch of the crevices less steep, and the surrounding rock less disturbed than in the Ueberoth mine; the strike of the crevices was more to the west, and the blende came nearer to the surface.

The Saucon mine, however, affords the simplest and best illustration of this form of deposit. It is distant about a quarter of a mile, and was originally leased by the Passaic Zinc Company, by whom it was sublet to the Lehigh Zinc Company on high royalties. When the rich deposit of calamine first discovered was apparently exhausted, this sublease was surrendered by the latter company, and in 1875 the original lease passed to the Bergen Point Zinc Company, by whom the mine has been 'worked ever since. A face of blende was uncovered at the western extremity of the open pit, and the ore followed under a heavy cap of limestone for a distance of 250 feet up to the property of the Lehigh Zinc Company on the west. On this property it was reached at a depth of 110 feet, under 100 feet of solid limestone, and was followed 150 feet farther on the course of its strike. On both properties it was followed to a depth of nearly 200 feet. In the fall of 1879 all the property of the Lehigh Zinc Company passed into the hands of its bondholders under foreclosure of its mortgages, and in the spring of 1880 all the mining property was sold to the proprietors of the Bergen Point Zinc Works. The workings of these two mines, taken together, show a remarkable regularity of width, pitch, and course, and the deposit is clearly shown to be a large chimney or chute of ore of irregular cross-section, which, however, preserves a lenticular shape, the longer axis of which is about 60 feet, and pitches to the south at an angle of about 30°; the trans