and the articles designated by the figures impure gold is added, and the process thus are thus explained: 1. Reservoir for oxygen. 2. hydrogen. 3. Hydrogen generator. 4. Oxygen 5. Blowpipe. 6. Tuyere. 7. Rolls for converting the metal into sheets. 8. Gasometer. 9. Water pipes. 10. Pan. 11. Moulds in which the loose pieces of metal are compressed. goes on till a considerable amount of iridium is concentrated into the alloy of gold and silver, from which it is at last obtained by dissolving these metals. According to the statement of Dr. Thèvenet published in the Annales des Mines (vol. xvi., 1859), iridium is collected at the gold-washings along the sea-coast of Oregon, and is sometimes quite equal in quantity to the gold. He describes it as white, glistening, very heavy, its specific gravity being 20 to 21, very hard, and resembling sand, its angles slightly flatCrucibles for chemical use are prepared by tened and rounded by friction. It is accomthe ingenious method called spinning. A panied by platinum and rhodium. After disk of the metal is securely fixed against the one of the storms that prevail along this end of the mandrel of a lathe, and, as it re- coast, the miners at low tide collect the volves rapidly, a blunt point is pressed upon black sand and carry it to the washing and its surface, causing the plate to gradually amalgamating apparatus, in which it is stirred bend over and assume the desired form. with mercury and then treated upon the The large platinum retorts used in the man- shaking tables. Though by their rude procufacture of sulphuric acid are imported from esses they probably lose of the precious Paris. The whole amount of platinum metals, they sometimes collect several ounces brought to the United States for the year a day of gold to the man. Near Fort Or1850 was 34,000 oz. troy, which, at the ford, to the north of Rogue River, about custom-house valuation of $6.10 per oz., amounts to $200,000. The importation since that time has been very irregular, but never equal to this. The amount of scraps remelted by Dr. Roberts is about 1000 oz. a year. IRIDIUM AND OSMIUM. An alloy of these metals in fine grains of excessive hardness is found very frequently with platinum and with the gold which is refined at the mints. It is of interest from the use to which it is applied in forming the nibs of gold pens; and for this purpose the small grains are purchased by the pen-makers sometimes at the rate of $250 an ounce. From this quantity they may select from 8000 to 12,000 points of suitable size and shape for use. The alloy is known as iridosmium, and is also very generally called iridium. At some seasons it has been quite abundant in the gold presented at the New York assay office; but recently it is more rare. As it does not fuse and alloy with the gold, it appears in specks upon the bars of this metal. The method of separating it is to melt the gold with a certain portion of silver, as in the usual refining process. The alloy thus obtained being less dense than the melted gold, the particles of iridium settle in the lower portions; the upper is then ladled off, and the metals are parted. More of the 15 per cent. of iridium is found with the gold. Still further north, between Cape Blanco and Coquille, the metals collected consist of about 45 per cent. iridium and 5 per cent. platinum. Between Randolph and Cape Arago the metallic grains are very light and in extremely thin scales; they consist of 70 per cent. iridium and 6 per cent. platinum. Further north, the iridium continues almost as abundantly, but mostly in very fine particles. One piece was shown to Dr. Thèvenet as a great curiosity which was as large as a grain of rice. In sifting more than 50 lbs. of iridium, he states that he had not seen a single specimen of one quarter this size. CHAPTER VII. MERCURY. THIS metal, which is extensively employed in the arts, especially in the treatment of gold and silver ores by amalgamation, in the combination of amalgams for coating mirrors, etc., in the construction of barometers and thermometers, and other philosophical instruments, in the manufacture of the paint called vermilion, for several medicinal preparations, and for a variety of other purposes, was not classed among the productions of the United States until after the acquisition of Califor many years past, the lessees from the Spanish government, in whom the title is vested, have been the Rothschilds and other bankers of Europe; but their contracts with the government have varied from time to time, thus affecting the price at which the product was held.* nia, when mines of its principal ore were opened, which have been extensively worked, as will be described below. Mercury, which is the only fluid metal, is found both in a native state, dispersed in drops among the slates that contain the veins of its ores, and also occurs in combination with sulphur in the ore called cinnabar, a compound of one atom The mines next in importance have been of mercury and one of sulphur, or of 86.2 those of Idria in Carniola, belonging to the per cent. of the former, and 13.8 per cent. Austrian government. These, for some of the latter. Some other natural compounds years previous to 1847, had produced an are known, which are not, however, of much annual average of 358,281 lbs. of mercury, importance. Cinnabar is almost the exclu- and since that time, the production has vasive source of the metal. This is a very ried, sometimes reaching 600,000, and even heavy, brilliant ore of different shades of red; over 1,000,000 lbs. per annum. The other is readily volatilized at a red heat, giving off mines of Europe do not probably produce fumes, when exposed to the air, both mer- 200,000 lbs. On the American continent curial and sulphurous; but in tight vessels it many localities of the ores have been worked sublimes without decomposition, and if lime to some extent; but although the consumpor iron be introduced with the ore into re-tion is very great at the silver mines of torts, the sulphur is retained in combination Mexico, amounting, as estimated by Humwith the new element, and the mercury es- boldt, to 16,000 quintals of 200 lbs. each, capes in vapor, which may be condensed three fourths of the supply was then derived and recovered in the metallic state. On from the European mines. In 1782, merthis principle the process for collecting mercury was even brought to South America cury is based. The ores of mercury are found in almost all the geological formations, but the productive mines are only in the metamorphic or lowest stratified rocks, and in the bituminous slates of the coal measures. In order to appreciate the importance of the mines of California, it is necessary to understand the extent of the demand for this metal, and the sources which have supplied it. From the time of the ancient Greeks and Romans, mercury has been held in high estimation, and has been furnished from the same mines, which have ever since produced the chief part of the product of the world. Pliny states that the Greeks imported red cinnabar from Almaden in Spain, 700 years before the Christian era, and in his own time it was brought to Rome from the same mines to the amount of 700,000 lbs. annually. In modern times the production amounts to 2,700,000 to 3,456,000 lbs. per annum, and is chiefly obtained from two veins, one about 2 feet, and the other 14 feet thick, which, meeting in a hill about 125 feet high, spread out to a thickness of nearly 100 feet. The ores are of small percentage, yielding about only of mercury. I 10 The greatest depth of the workings was only about 330 yards several years ago. After the metal has been extracted from the ores, it is packed in iron bottles or flasks holding 763 lbs. each, and is taken to Cadiz for shipment. For from China, where it was formerly largely extracted in the province of Yunnan. Yet in the early years of the Spanish conquest Peru was a large producer of the metal, its most important mines being in the province. of Huancavelica, where no less than 41 different localities of the ore have been known; but at present the whole product of the country is supposed not to exceed 200,000 lbs. A large portion of this product is from the Santa Barbara, or the "Great Mine,” which has been worked since 1566. The mines of Chili and the numerous localities at which the ores have been found in Mexico supply no metal of consequence. Dumas estimated, not long since, the total annual production as follows: increase of production, hereafter, will be The operations at the Enrequita mine are carried on from the face of the hill, some 5 or 6 levels one above another being carried into the mountain up and down its slope. The most extensive of these is the adit level In California the existence of large quantities of cinnabar was known long before the real character of the ore was understood. It was found along a range of hills on the southern side of the valley of San José, about 60 miles south-east from San Francisco. For an unknown period the Indians had frequented the locality, coming to it from distant places, even from the Columbia river, to obtain the bright vermilion paint with which to ornament their persons. With rude implements, such as the stones they picked from the streams, they extracted the ore from the flinty slates and shales in which it was found, and in their search for it they excavated a passage into the mountain of about sixty feet in length. In 1824 the attention of the whites began to be directed to this curious ore, and some of the Mexicans sought to extract from it gold or silver. Other trials made of it in 1845 resulted in the discovery of its true character, and operations were thereupon commenced to work it by one Andres Castillero. Owing, however, to the disturbed at the base, which is about 600 feet long. state of the country, little was done until 1850, when a company of Mexicans and English engaged vigorously in the extraction and metallurgical treatment of the ore, and established the mine which they called the New Almaden. In 1858 a stop was put upon their further proceedings by an injunction issued by the United States court on the question of defective title. From the testimony presented in the trial, it appeared that the company in the course of eight years had produced full 20,000,000 lbs. of metal, and realized a profit of more than $1,000,000 annually. The Americans who claimed the mine directed their attention to the discovery of new localities of the ore, and succeeded in finding it upon the same range of hills within less than a mile of the old workings. Here they opened a new mine in December, 1858, which they named the Enrequita, and in June, 1860, a company was formed in New York for working it under the name of the "California Quicksilver Mining Association." The following are the returns of their operations to the latest dates in September, 1859, the product of mercury was 14,400 lbs.; October, 28,650; November, 27,525; December, 28,425; January, 1860, 27,000; February, 16,950; March, 25,500; April, 33,700; May, 46,275; June, 48,750; July, 50,000; August, 79,866; September, 66,096. The Shafts are sunk from this to the depth of about 50 feet; but the principal workings are in the upper levels for 300 feet over the adit. These are exceedingly irregular, owing to the unequal distribution of the ore through the argillaceous slates. It lies in beds included between the strata of these lower silurian rocks, dipping with them at a very steep angle, and winding with the contortions of the strata. The workings follow the bunches of ore as they lead up or down, and to the right or left. Shafts occasionally penetrate from one level to another, but no regular system of working appears to have been adopted. With the cinnabar is intermixed some arsenical iron and copper pyrites, and the ore and slates are both traversed by veins of carbonate of lime, some of which are retained in hand specimens of the cinnabar. On the same range of hills, at its western extremity, the Santa Clara Mining Company, of Baltimore, has opened a mine called the Guadalupe, the product of which for the year 1860 was about 200,000 lbs. The total production of the quicksilver mines, from the beginning of 1853 to the close of 1858, was about 177,578 flasks, or 13,318,350 lbs. In 1866, the California mines produced 3,505,878 lbs, and in 1867, 3,840,957 lbs. Litigation has prevented most of them from being fully worked. METALLURGIC TREATMENT. the furnace, so as to receive the vapors from all the retorts. The mercury, as it is condensed, falls down to the bottom, and is let out through a pipe by a contrivance that prevents the water flowing with it from the condenser. At the Enrequita mine each bench of three retorts requires a little over a cord of oak wood a day for heating. Four benches, in operation from September, 1859, employed 6 men in charging and discharging, working in 2 shifts of 3 men, besides 3 firemen, each working 8 hours. Two men besides these were employed in mixing the ores for the retorts. In June, 1860, the produc tion of these furnaces, from 1000 cargas of ore of 300 lbs. each, was about 50,000 lbs., or about 17 per cent. In conducting the furnaces, the workmen are seriously affected by inhaling the mercurial vapors. They are sometimes even salivated, and are often obliged to abandon the business for a time. The horses and mules also suffer from the noxious fumes, and many are lost in consequence. But no injurious effects are experienced among those employed in the mines, the cinnabar being always handled with impunity. gas-works. Three are set together in a bench of brick-work, and each one is furFrom cinnabar not contaminated with nished with an eduction pipe inserted in strange metals, the method of obtaining the the end and leading down into water confluid mercury is very simple. In the early tained in a large cylindrical condenser of workings of the New Almaden mine, the iron. This is placed along the front line of clean ores were placed in the common "try pots," such as are used by the whalers, and a cover being tightly luted on, a fire was started under them, and the mercurial vapors escaped through a tube inserted in the lid and were condensed in cold vessels. Afterward furnaces were constructed in brick-work upon a large scale, each one provided with a chamber or oven 7 feet long, 4 feet wide, and 5 feet high, corresponding to the chamber of the reverberatory furnaces; and into this was introduced a charge of 10,000 lbs. of clean ore separated from the poorer portions after the whole had been broken up. With the ore was mixed a portion of lime to combine with and retain the sulphur. A partition of brick-work separated the oven from the fire-room, and the bricks in this partition were so laid as to leave open spaces for the flame from the burning wood to pass through. On the opposite side of the oven another partition separated this from a chamber of its own size, the only communication between them being by a square hole in one of the corners close to the roof. This chamber connected with another by an opening in the opposite corner near the floor, and this arrangement was extended through eight chambers. Between the last one and the tall wooden flues through which the smoke and vapors finally passed out into the open air was placed a long wooden box provided with a showering apparatus. As the cinnabar was volatilized by the flame The principal uses to which mercury is playing over the charge, the vapors were applied have already been named. carried through the condensing chambers, largest quantities are consumed in working depositing in each a portion of mercury, and gold and silver ores. The principle of the in the showering box they underwent their amalgamating process is explained in the final condensation. From the bottom of account of the treatment of gold ores. each chamber the metal flowed in gutters to the arts amalgams are applied to many usethe main conduit which led to the great iron ful purposes, of which the most important is reservoir sunk in the ground. From this it coating the backs of looking-glass plates with was poured into flasks through brushes tin amalgam. Silver was originally emwhich intercepted the scum of oxide of mer-ployed instead of tin, and the process is still cury. The method proved very wasteful, called "silvering." It is conducted at sevfrom the leakage of the vapors through the eral establishments in the United States on brick-work; and it has been abandoned for an improved process, in which the pulverized ores mixed with quicklime are charged inte large cast-iron retorts very similar in their form and setting to those employed at the The view of the works presents their appearance in 1852, as sketched by J. R. Bartlett, Esq. It was first published in his "Personal Narrative" (New York, 1854). USEFUL APPLICATIONS OF MERCURY. The In the old Venetian plan, which has been in use for 300 years. The largest mirrors are prepared by Messrs. Roosevelt & Sons, in New York, from the French plates which they import. The process is a simple one, |