owing to the mines themselves being in former metal. As the production of the great part exhausted. The only sufficient United States fell off that of Great Britain sources known from which the increasing increased from 64,000 tons in 1850 to 73,129 supplies required from year to year can be tons in 1856, and 96,266 tons in 1857, thus furnished, are the mines of Great Britain considerably exceeding one-half of the whole and Spain, though should the argentiferous production of the globe in this metal, which lead mines of Mexico ever be worked for in 1854 was rated at about 133,000 tons. the lead as well as the silver they contain, At that time the production of Spain was they might furnish large quantities of the rated at 30,000 tons, and of the United States at 15,000 tons. Years. Pig lead from Orleans. 1832...... 8,540,000 1833... ...12,600,000 1834. .14,140,000 1835. ..16,000,000 For the year ending June 30, 1859, the | ple methods. The earlier operations were imports of lead are given at 64,000,000 pounds, worth nearly $2,700,000. Of this about $57,000 worth were re-exported to foreign countries, besides American lead to the value of $30,000, and a small amount of manufactured lead. The limited to smelting the ores in log furnaces. Upon a layer of logs placed in an inclosure of logs or stones piled up, split wood was set on end and covered with the ore, and over this small wood again. The pile was fired through an opening in front. LEAD SMELTING. The lead mines of the combustion of the small wood removed from United States being scattered over wide ter- the ore a portion of the sulphur, and the reritories, and their products being nowhere duction was completed by the greater heat brought together in large quantities, the proc- arising from the burning of the logs. The ess of reducing the ores has been conducted lead run down to the bottom and out in in small establishments and by the most sim-front into a basin, whence it was ladled into the moulds. The loss of metal was of to receive the melted lead that overflows, course very large; but a portion was recovered by treating the residue in what was called an ash furnace. The process is still resorted to in places where no furnaces are within reach. But wherever mines are opened that promise sufficient supplies of ore, furnaces are soon constructed in their vicinity. Those in use are of two sorts: the Scotch hearth and the reverberatory. Besides these, another small furnace is often built for melting over the slags. This is little else than a crucible built in brick-work, and arranged for the blast to enter by an aperture in the back, and for the metal to flow out by another opening in front. The Scotch hearth is a small blast furnace, but resembles the open forge or bloomary fire for iron ores. It has long been in use in Europe, and is the most common furnace at our own mines. In this country it has been greatly improved by the introduction of hot blast; and in its most perfect form is represented in the accompanying figures; figure a being a vertical section from front to back, and figure b a horizontal section. and conduct it by the groove into the basin, receiver for giving regularity to the current sides being kept open at the same time to alof air. With such an apparatus, the smelter low free access of air. The oxidation of the can apply the blast with great advantage at sulphur is expedited by almost constant times to help loosen up the charge and stirring of the charge, which brings fresh throw the flame through every part of it. portions to the surface, causing an evolution The ores are prepared for smelting by sep- of white fumes. As these begin to diminish, arating from them all the stony and clayey the fire is started on the grate, and the heat particles, and as much as possible of the is raised till the charge softens and the pieces blende and other impurities that may ac- of ore adhere to the rake. The doors are company them. This may require a succes- then closed, and the fire is urged for a sion of mechanical processes, in which the quarter of an hour, when the smelter opens ores are crushed to fine fragments and dress- the door to see if the metal separates and ed by jigging and screening under water. flows down the inclined hearth. If the sepNot only is the labor and cost of smelting re-aration does not go on well, it is hastened duced by the purity of the ore, and especially its freedom from blende and pyrites, but the quality also of the metal is thereby improved. Lead that contains iron is not adapted for the manufacture of white-lead. The American metal being generally free from this brings a higher price than Spanish or English lead. With pure ore a cord of wood may be made to produce four tons of lead; and each furnace 7,500 lbs. every 24 hours; a smelter and his assistant managing the operation for 12 hours. At Rossie large quantities of lead have thus been smelted at a daily cost for labor of $5, and for fuel of $1.50, making $1.75 per ton. In Wisconsin, before the use of the hot blast, each furnace-shift was continued from 8 to 10 hours, until 30 pigs of lead were produced of 2,100 lbs. weight, at an expense of about $4 for labor, and $1.50 for fuel. by opening one of the doors, partially cooling the furnace, and stirring the charge. The fire is then again urged. If the slags which form seem to require it, he treats them with a few shovelfuls of lime and fine coal; and when, after having flowed down into the lower portion of the hearth, they are brought into a doughy consistency, the smelter pushes the slag to the opposite upper edge of the hearth, from which it is taken out through a door on that side by his assistant, while he lets off the lead into the receiver. The separation by this method is not so perfect as by the Scotch hearth, and the expense of fuel is greater; but the reverberatory is worked without the necessity of steam or water power, which is required to raise the blast for the other process. The slags of the reverberatory contain so much lead that they are always remelted in the slag furnace. Those of the Scotch hearth, when pure ores are employed, are sufficiently clear of metal without further reduction. In Europe other sorts of furnaces are in use, which are adapted particularly for ores of poorer quality than are ever smelted in the United States. The other form of furnace-the reverberatory resembles others of this class employed in smelting copper ores. The sole, or hearth, upon which the ores are spread, is about 8 feet in length by 6 in breadth, and is made to incline rapidly toward an aperture on one side, or at the end under the chimney, and out of which the lead is allowed at the end of each smelting to In the Hartz mountains, at Clausthal, flow into a receiver outside. The charge is argentiferous silver ores containing much supplied either through a hopper in the silica are worked in close cupola furnaces, arched roof, or through the holes in the into which only enough air is admitted to sides, which also serve for admitting the consume the fuel. The object is not to pokers used by the workmen to stir up the roast out the sulphur, but to cause this to charge. Unless the galena has been pre- combine with the granulated cast iron or viously calcined or roasted- -a process neces-with the quick-lime, either of which is mixed sary for poor ores only--this is the first thing to be attended to in all the smelting operations. In the large charge of 30 cwt. of ore this usually takes the first two hours of the process, and is effected in great part by the heat remaining in the furnace from the preceding operation, the doors at the with the ores to flux them and form a fusible compound with the sulphur, through which the metallic lead can easily find its way to the bottom. The production of a silicate of lead is thus avoided, which is a difficult compound to reduce, and is always formed when much silica is present. This process will probably be applied to some of the silicious ores of the United States, and may be particularly suited to the Washoe ores of California. in the fumes, but in the working of argentiferous lead ores, a portion of the silver too is carried off and deposited with them. The fumes collected at the works of the Duke By all the methods of reducing lead a of Buccleuch yield one-third their weight of great loss is incurred by the volatilization of lead, and five ounces of silver to the ton. The a portion of the lead in white fumes, called loss of silver is of little importance in this lead ashes. These are carried up through country, where this metal is not obtained at the chimney of the furnace and fall upon the present time, unless it be at the Washthe ground in the neighborhood, poisoning ington mine, in North Carolina, and at the the vegetation and the water by the carbon- Washoe mines, in California; and conseate of lead, which results from the fumes. quently methods of separating it from the Trees even are killed, and the dogs die off, lead possess little more than scientific interest. and also the cattle. In Scotland the lead In the smelting of argentiferous lead ores, has been detected in chemical examinations the silver goes with the lead, being comof the bodies of animals thus killed, and it pletely dissolved and diffused throughout its was particularly noticeable in the spleen. substance. The usual way of separating it is For the injury thus occasioned at the fur- founded on the principle of the lead being a naces of the United States no remedy has metal easily oxidized and converted into the been applied, but at many of the great es- substance called litharge, in which conditablishments in Europe, where the loss of tion it lets go the silver, which has no affinity lead and the damage to the neighborhood either for the new compound of oxygen and is much more serious, attempts have been lead, or for the oxygen alone. The change made to arrest the fumes, by causing them is effected by melting the lead in the shallow to pass through long flues in the chimney basins called cupels, formed of a porous stacks, in which the particles on cooling earthy material, as the pulverized ashes of would settle down; and their cooling has burned bones, kneaded with water, and been hastened by showers of water falling mixed in a framework of iron. When dried, among the vapors. Flues have been extended these are set in a reverberatory furnace, and great distances beyond the works, and have the pigs of lead are melted upon their surbeen found much more efficient than any face. After being thoroughly heated, a curform of condensation by sudden cooling. rent of air is made to draw through an openSome of the works constructed for this pur- ing in the side of the furnace directly upon pose are very remarkable for their great the face of the melted metal. extent and the saving they have effected, the lead, and the yellow litharge with more and similar ones may perhaps be found well or less red oxide, called minium, collects in worthy of construction at some of the smelt- a thin film upon its surface, and floats off to ing establishments in the United States. At the edge, sinking into and incrusting the the works of Mr. Beaumont, in Northum- cupel and falling over its side into a recepberland, England, horizontal or slightly in- tacle placed to receive it. This process goes clined galleries have been completed in stone- on, the lead gradually disappearing as the work, 8 feet high and 6 feet wide, for an oxygen combines with it, till with the reextent of 8,789 yards (nearly five miles). moval of the last films of oxide the melted This is from one mill alone. The same pro- silver suddenly presents its brilliant, perfectly prietor has connected with other mills in unsullied face. The oxide of lead may be the same district and in Durham four miles collected and sold for the purposes of of galleries for the same purpose. The litharge, The litharge, as for a pigment, for use in the writer who gives the account of these in the manufacture of glass, etc.; or it may be recent edition of Ure's Dictionary, by Rob- mixed with fine coal and converted back ert Hunt, remarks: "The value of the into lead, the carbon of the coal effecting lead thus saved from being totally dissipated this change by the greater affinity it has at and dispersed, and obtained from what in a high heat for the oxygen, than the lead has common parlance might be called chimney to retain it. By this process, known as sweepings, considerably exceeds £10,000 cupellation, lead is hardly worth treating for sterling annually, and forms a striking illustration of the importance of economizing our waste products." Not only is lead lost This oxidizes silver, unless it contain about 10 ounces to the ton of the precious metal; and it was therefore an important object to devise a fectly level table, covered with fine sand, and furnished with a raised margin; and when the metal has spread over this, a couple of workmen, one on each side, carry along a bar supported upon the margin, pushing forward the excess of lead above that necessary for the required thickness, till it falls over the end of the table. By the other method, called milling, the lead is cast in a plate, 6 or 7 feet square, and 6 inches thick, and this being taken up by a crane, is placed upon a line of wooden rollers, which form a flooring for the length it may be of 70 or 80 feet and a width of 8 feet. Across the middle of this line are set the two heavy iron rolls by which the lead plate is compressed, as it is passed between them. The top of the lower roll is on a level with the top of the wooden rollers, and the upper roll is so arranged that it can be set nearer to or further from the lower one, as the thickness of the plate requires. method of saving with economy the silver the shipment of other ores of the different lost in the large quantities of the poorer metals from various sources; and it is to be argentiferous leads. Such a method was hoped that it will hereafter be found more accidentally discovered in 1829 by Mr. advantageous to send ores to New York to Pattinson, of Newcastle, and is now exten- be reduced, than to the smelting establishsively in use in Europe for the poorer silver- ments on the other side of the Atlantic. leads, cupellation being preferred for the USEFUL APPLICATIONS OF LEAD.-A conricher. He observed that when the lead siderable part of the lead product of the world containing silver forms crystals, as it is is converted into the carbonate, known as stirred while in a melted state, the crystals white lead, and used as a paint. The princontain little or none of the silver, and may cipal articles of metallic lead are sheet lead, be removed, thus concentrating the silver lead pipe, and shot. Sheet lead is manuin the portions left behind. This crystal-factured in two ways. The melted lead is lizing process is applied in the large way as upset from a trough suspended over a perfollows: Cast iron pots are set in brickwork side by side, capable of holding each one 4 or 5 tons of lead. The middle one is first charged, and when the lead is melted and stirred, the fire is removed under the next pot to the right; and into this crystals of lead as they form are ladled by means of a sort of cullender, which lets the fluid lead fall back. This instrument is kept hotter than the lead by frequently dipping it in a pot of lead over a separate fire. When fourfifths of the lead have been transferred to the pot to the right, the remainder, which contains all the silver, is removed to the next pot to the left, and the middle pot is then charged with fresh lead, which is treated in the same manner. The process is repeated with each pot, as it becomes full, four-fifths of its contents going to the next pot to the right, and one-fifth to the next to the left, and thus the lead is finally discharged into moulds at one end, and the argentiferous alloy, concentrated to the richness of 300 Lead pipe was formerly made by turning ounces of silver to the ton, is run into bars up sheet lead and soldering the edges; and about 2 inches square. From these the is still prepared in this way for the large silver is obtained by cupellation. At one sizes, as those over six inches diameter. Afestablishment in England, that of Messrs. ter this a method was contrived of casting Walker, Parker & Co., the weekly product the lead in a hollow cylindrical plug, its of silver is from 8,000 to 10,000 ounces. inner diameter of the bore required, and then Whenever the lead mines of the eastern drawing this down through slightly conical states are made to yield regular returns of dies of decreasing diameter, a mandril or lead, the separation of its silver is likely to steel rod being inserted to retain the uniform be carried on in independent establishments, diameter of the bore. Pipes made in this supplied like the copper-smelting works with way were limited to 15 to 18 feet in length, material from various sources. Works hav- and the metal was full of flaws. Many ating these objects in view were established tempts have been made to cast long lengths in the fall of 1860, at Brooklyn, New York, of lead pipe, all of which have proved unsucby Messrs. Bloodgood & Ambler, and will cessful. In 1820 Thomas Burr, of England, commence operations with the smelting of first applied the hydraulic press to forcing the Washoe silver-lead ores from California, lead, when beginning to solidify in cooling, of which over sixty tons have been delivered through an annular space between a hollow at the works for reduction. Their success-ring and a solid core secured in its centre. ful treatment will no doubt be followed by He thus produced pipes of considerable |