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sides in deposits, which gradually diminish in their proportions of oxide of cobalt. The first are of the deepest blue, and are called azure; but of this, and of the succeeding fainter shades, there are many varieties, distinguished by peculiar names. When finely powdered, smalt is applied to coloring wall papers, and blueing linen, besides being incorporated with porcelain to impart to it permanent blue shades. The great value of oxide of cobalt, amounting to several dollars per lb., renders it an important object to fully develop the resources of the country in its ores, as well for export as for domestic use. In 1856 there were imported into Great Britain 428 tons of cobalt ore, and 34 tons of oxide of cobalt.

stances. The ores are sought for all over chloride of lime, and heating the product to the world for the supply of the British man- redness. Smalt is a preparation of cobalt ufactories of porcelain, stained glass, etc. largely used in the arts as a coloring material, They are chiefly combinations of cobalt and consists of silicate of potash and cobalt. with arsenic, sulphur, and sometimes with It is in fact a potash glass colored by silicate nickel and iron. The compound known as of cobalt, and is prepared as follows: Zafsmaltine, or arsenical cobalt, was obtained fre is melted in pots, with suitable proporat Chatham, Conn., as far back as 1787, and tions of pure sand and potash and a little the mine has been worked for cobalt at dif- saltpetre. The other metals combine toferent times in the present century. The co-gether and sink in a metallic mass, which balt in the ore is associated with about an is called speiss. The glass containing the equal amount of nickel, and its proportion oxide of cobalt is ladled out and pouris said to have been less than two per cent. ed into water to granulate it, and is then Cobaltine, which is a compound of sulphur ground to powder. This being introduced 19.3 per cent., arsenic 45.2, and cobalt into vats of water, the colored glass sub35.5, is the most productive ore of this metal, but is not met with in this country. Varieties of pyritous cobalt have been found in Maryland in quantities too small for working; and also at Mine la Motte in Missouri, associated with a black earthy oxide of cobalt and black oxide of manganese. In other places, also, oxide of cobalt, in small quantity, is a frequent accompaniment of manganese ores. Mine la Motte has furnished a considerable amount of the cobalt oxide, but the beds in which it is found are not of permanent character, and are so far exhausted as to be no longer worked with profit. A similar ore, accompanied with nickel, appears to be very abundantly distributed among the talcose and quartzose slates in Gaston and Lincoln counties, North Carolina. It is thrown out with a variety of other ores, as galena, blende, titaniferous Nickel is a metal of some commercial imiron, etc.. in working the gold mines of this portance, and is employed chiefly for proregion; and it is mixed among the great ducing, with copper and zinc, the alloy beds of hematite, found in the same district, known as German silver. The proportions which are the product of the decomposition of these metals are not constant, but the of beds of pyritous iron. In some places it most common in use are eight parts of copper is so abundant that the strata containing it to three cach of nickel and zinc. The larger are conspicuous where the roads pass over the proportion of copper, the more easily the them, by the blackness of the gossan (de- plates are rolled; but if more is used than composed ore) or wad. Prof. H. Wurtz, the relative amounts named, the copper soon who describes these localities (see "American becomes apparent in use. The new cent Journal of Science," 2d series, vol. xxvii., p. contains 12 parts of nickel to 88 of copper, 24), is of opinion that the earthy oxide of and the manufacture of this adds somewhat cobalt is the gossan of the sulphuret of this to the demand. The metal has been mined metal, existing unaltered in the rocks below. at Chatham, Conn., and is met with at Mine Oxide of cobalt, obtained in a crude la Motte and other localities where cobalt state from the washed arsenical ores, is is found. It occurs in greatest abundance at known as zaffre or saflor, and in this condi- an old mine in Lancaster county, Penn., tion it is a commercial article. It is refined where it is associated with copper ores. The by separating the arsenic, iron, and other for- mine was originally worked for copper, it is eign substances, by precipitating them from said, more than one hundred and thirty years the solution in hydrochloric acid; and the ox- ago, and was reopened for supplying nickel ide is finally obtained by precipitating with for the U. S. Mint, on the introduction of

NICKEL.

the new cent in 1857. The sulphuret of nickel. containing, when pure, 64.9 per cent. of nickel, and 35.1 per cent. of sulphur, is in very large quantity, in two veins of great size, one of which has been traced over 600 feet, and the other over 900 feet in length. In 1859 it was producing at the rate of 200 tons of nickel ore and ten tons of copper ore per month. A pyritous variety of nickel ore, called siegenite, is found at Mine la Motte, Missouri, and in Carroll county, Maryland. In Gaston and Lincoln counties, North Carolina, similar ore was found by Prof. Wurtz, as noticed in the remarks on cobalt, above.

CHROME OR CHROMIUM.

The state

mine 7 or 8 tons of excellent ore a day,
the best of which was directly placed in
barrels for the foreign market, and the
poorer was dressed and washed for the Bal-
timore, and other home markets.
line mine, in the same vicinity, worked to
about the same depth, had produced several
thousand tons. The supplies of this ore are
always of uncertain continuance.

leys and ravines, and dug out in sinking shallow pits and trenches over the surface. The ore thus obtained was called "sand chrome," and for a time it had been worth $45 per ton, and thousands of tons had been collected and shipped, principally to Baltimore. At the period named these superficial deposits were mostly exhausted, and the value of the ore was only about $25 per ton. This, however, was sufficient to sustain regular mining operations, which were then carried on upon the veins found in the serpentine, a little west of the east branch of the Octorara Creek. Wood's chrome mine, near the Horse-shoe Ford, was at that time about 150 feet deep, and The ore of this metal, known as chromic the workings had been extended north-east iron or chromate of iron, has been mined and south-west about 300 feet, upon an for many years in the United States, both irregular vein of chrome ore, which lay at for exportation and domestic use. It is the an inclination of about 45° with the horsource whence the chrome colors are ob- izon toward the north-west. The ore, in tained that are largely used in the arts, es- places, formed bunches, which attained a pecially in dyeing and calico printing. The width of 20 feet, and then thinned away name of the metal, from a Greek word to nothing. Four men obtained from the meaning color, was given in consequence of the fine colors of its compounds. It usually consists of the sesquioxide of chromium in proportion varying from 36 to 60 per cent., protoxide of iron from 20 to 37 per cent., alumina sometimes exceeding 20 per cent., and more or less silica, and sometimes magnesia. Its value consists only in the firstnamed ingredient. The localities of the ore are in the serpentine rocks of different parts of the United States, as in the Bare Hills, near Baltimore, and near the Maryland state line on the southern edge of Chester and Lancaster counties, Pennsylvania. In small quantities the ore is met with at Hoboken, Staten Island, and other places near New York city. It is found in several towns in Vermont, but the largest veins of it are in Jay, in the northern part of the state. The composition of this ore was found by Mr. T. S. Hunt to be 49.9 of green oxide or sesquioxide of chromium, 48.96 of protoxide of iron, and 4.14 per cent. of alumina, silica, and magnesia. Though the quantity of the ore in this region is reported to be large, the principal supplies of the country have been obtained in Maryland, and from the mines just over the state line in Pennsylvania. The ore, as recently as 1854, was found in loose fragments among the disintegrated materials of the serpentine upon the tracts called the barrens, and was gathered up from the val

USEFUL APPLICATIONS. Chromate of iron is used chiefly in the production of chromate of potash, and from this the other useful chromatic salts are obtained. The object in view in the chemical treatment of the ore is to convert the sesquioxide of chromium into the peroxide or chromic acid, and cause this to combine with potash. This may be effected by various methods, as by exposing a mixture of the pulverized ore and of saltpetre (nitrate of potash) to a strong heat for some hours. The chrome is peroxidized at the expense of the oxygen of the nitric acid of the saltpetre, and the chromic acid combines with the potash; or if the ore is mixed with carbonate of potash and calcined, the peroxidation of the chrome is effected by admission of air into the furnace, and the same product is obtained as in the employment of saltpetre. The introduction of lime hastens the operation. Other mixtures also are used for the same purpose. When the calcined matter, having been drawn out from

the furnace, is lixiviated with water, the as on Hard-labor Creek, Edgefield District, chromate of potash is dissolved and washed S. C. Usually the ore is found in loose out, and is afterward recovered in the form pieces among the clays which fill the irreguof yellow crystals on evaporating the water. lar cavities between the limestone strata; From chromate of potash the other salts are its quantity is of course very uncertain, readily produced. Chrome yellow, used as and its mines are far from being of a permaa paint, is prepared by mixing chromate of nent character. Oxide of iron is commonly potash with a soluble salt of lead, and col- mixed with the manganese ore, reducing its lecting the yellow precipitate of chromate of richness, and at the same time seriously inlead which falls. A bright red precipitate juring it for some of the purposes to which is obtained by thus employing a salt of mer- it is applied. As obtained from the mines, cury, and a deep red with salts of silver. the assorted ore is packed in barrels and Chrome green is produced by mixing Prus- sent to the chemical establishments, where sian blue with chrome yellow. Some new it is employed principally in the manufacand very interesting compounds of the scs-ture of chloride of lime or bleaching powquioxide of chromium with different bases der. For this purpose the pulverized black have been recently obtained by Prof. A. K. oxide of manganese is introduced into hydroEaton of New York, and in consequence chloric acid, and this being heated a double of their decided colors and the extraordi- decomposition takes place, a portion of its nary permanency of these against powerful chlorine is expelled, and the hydrogen that reagents applied to remove them, the salts was combined with it unites with a part of were employed for printing bank-notes. the oxygen of the pyrolusite. The chloThough they proved to be all that was re- rine, which it was the object of the process quired as to the colors themselves, the steel to obtain, is then brought in contact with plates were so rapidly cut by the excessively hydrate of lime, and uniting with the calsharp and hard powders, however finely they cium base, forms the bleaching powder. A were ground, that it was found necessary to similar result is obtained by mixing the oxabandon their use. The new salts were chro- ide of manganese with chloride of sodium mites-that of iron having a dark purple col- (common salt), and adding sulphuric acid. or; of manganese, a lighter shade of the By these operations a weight of oxygen same; of copper, a rich blueish black; of equal to about one third that of the pure zinc, a golden brown; of alumina, a green, ore may be obtained, and this may be apsomewhat paler than that of the sesquiox-plied to any of the purposes for which oxy

ide.

MANGANESE.

Though this is a metal of no value of itself, one of its ores, called pyrolusite, is a mineral of some commercial importance, chiefly on account of the large proportion of oxygen it contains, part of which it can be easily made to give up when simply heated in an iron retort. The composition of pyrolusite, or black oxide of manganese, is 63.4 per cent. of manganese, and 36.6 per cent. of oxygen. It is a hard, steelgray ore, resembling some of the magnetic iron ores, and is often found accompanying iron ores, especially the hematites. In the United States it is met with in various localities along the range of the hematites, from Canada to Alabama, and has been mined to considerable extent at Chittenden and Bennington, Vermont; West Stockbridge and Sheffield, Mass.; on the Delaware river, and near Kutztown, Berks co., Penn.; and abounds in different parts of the gold region,

gen not absolutely pure is required. Black oxide of manganese is also used to decolorize glass stained green by the presence of the protoxide of iron. Its own amethystine tint is supposed to neutralize the optical effect of the greenish hue of the iron. Pure pyrolusite, free from iron, might be shipped to profit to Liverpool, where it is worth $35 to $40 per ton, but inferior ore would involve bills of cost. The chemically prepared permanganate of potassa has come into extensive use as an anti-septic, of late years.

TIN.

The very useful metal, tin, is not one of the products of this country, and there is no encouragement for hoping that its ores will ever be found in workable quantity. Its presence has been recognized in a few small crystals of oxide of tin, found in Chesterfield and Goshen, Mass., and it has been detected as a mere trace in the iron ores of the Hudson, and iron and zinc ores of New Jersey; it is also associated with some of

the gold ores of Virginia. In the town of Jackson, N. H., is a vein of arsenical iron, containing thin streaks of oxide of tin. There have been discovered, also, some of the tin ores though not as yet in large quantity in Maine, in Missouri, in Texas, and in California. The last named, it is thought, may yet furnish considerable supplies. Tin is imported chiefly from the mines of Cornwall, England, and from Banca, and other islands of the Malay archipelago. The United States is one of the largest consumers of tin, sheet tin having been applied, through the ingenuity of the workers of this article in Connecticut, to the manufacture of a variety of useful utensils. What is called sheet tin is really sheet iron coated with a very thin layer of tin. The sheets are prepared in England by dipping the brightened iron sheets into a bath of melted tin. The process has been applied to coating articles made of iron, which are thus protected from rusting; and zinc is also used for similar purposes. Such are stirrups, bridle-bits, etc. Cast-iron pots and saucepans are tinned on the inside by melted tin being poured in and made to flow over the surface, which has been made chemically clean to receive the metal. The surface is then rubbed with cloth or tow. Tin is imported in blocks or ingots, and the metal is applied to the preparation of various alloys, as bronze or bellmetal, composed of copper and tin in variable proportions, commonly of 78 parts of copper, and 22 of tin; gun-metal, copper 90, and tin 10; pewter, of various proportions of tin and lead, or when designed for pewter plates, of tin 100, antimony 8, bismuth 2, and copper 2; and soft solder, consisting of tin and lead, usually of two parts of the former to one of the latter. Bismuth is sometimes added to increase the fusibility of the alloy.

CHAPTER IX. COAL.

To the early settlers of the American colonies the beds of mineral coal they met with were of no interest. In the abundance of the forests around them, and with no manufacturing operations that involved large consumption of fuel, they attached no value to the black stony coal, the real importance of which was not in fact appreciated even in

Europe until after the invention of the steam engine. The earliest use of mineral coal was probably of the anthracite of the Lehigh region, though it may be that the James River bituminous coal mines, 12 miles above Richmond, were worked at an earlier period than the Pennsylvania anthracites. The region containing the latter belonged to the tribes of the Six Nations, until their title was extinguished and the proprietary government obtained possession, in 1749, of a territory of 3750 square miles, including the southern and middle of the three anthracite coal-fields. In 1768 possession was acquired of the northern coal-field, and at the same time of the great bituminous region west of the Alleghany mountains. The existence of coal in the anthracite region could not have escaped the notice of the whites who had explored the country, for its great beds were exposed in many of the natural sections of the river banks and precipitous hills, and down the mountain streams pieces of coal, washed out from the beds, were abundantly scattered. The oldest maps now known, dating as far back as 1770, and compiled from still older ones, designate in this region localities of "coal;" but these were probably not regarded as giving any additional value to the territory.

The first recorded notice of its use was in the northern basin by some blacksmiths in 1770, only two years after the whites came in possession; and in 1775 a boat load of it was sent down from Wilkesbarre to the Continental armory at Carlisle. This was two years after the laying out of the borough of Wilkesbarre by the Susquehanna Land Company of Connecticut. From this time the coal continued to be used for mechanical operations by smiths, distillers, etc.; and according to numerous certificates from these, published in 1815, in a pamphlet by Mr. Zachariah Cist of Wilkesbarre, they had found it very much better for their purposes, and more economical to use than Virginia bituminous coal, though at the enormous price of 90 cents a bushel. Gunsmiths found it very convenient for their small fires, and one of them, dating his certificate December 9, 1814, stated that he had used it for 20 years, consuming about a peck a day to a fire, which was sufficient for manufacturing 8 musketbarrels, each barrel thus requiring a quart of coal. Oliver Evans, the inventor of the steam engine, certifies in the same pamphlet to his having used it for raising steam, for

volume of the "American Journal of Science," published in 1818, they are spoken of as already having been worked 30 years.

VARIETIES OF COAL.

which it possessed properties superior to those the Susquehanna to Columbia, Lancaster of any other fuel. Judge Fell of Wilkes- county, which, he states, caused much surbarre applied it to warming houses in 1808, prise to the inhabitants, that "an article with and contrived suitable grates for this use of which they were wholly unacquainted should it; but the cheapness of wood and the be thus brought to their own doors." This greater convenience of a fuel which every was the commencement of a trade which has one understood how to use, long prevented since been prosecuted to some extent by its general adoption. In the first volume running rafts of timber loaded with coal, and of the "Memoirs of the Historical Society sometimes with pig iron also, from the headof Pennsylvania," T. C. James, M.D., gives waters to the lower portion of the Susque"a brief account of the discovery of anthra- hanna. The bituminous coal mines on the cite coal on the Lehigh," in which he de- James River, 12 miles above Richmond, in scribes a visit he made to the Mauch Chunk Virginia, were also worked during the last mountain in 1804, where he saw the immense century, but at how early a period we are body of anthracite, into which several small ignorant. In an account of them in the first pits had then been sunk, and which was afterward worked, as it is still, as an open quarry. He states that he commenced to buru the coal that year, and had continued to use it to the time of making this communication in 1826. The discovery of this famous mass of coal was made in 1791, and in 1793 the "Lehigh Coal Mine Company" was formed to work it. But as there were no facilities for transporting the coal down the valley of the Lehigh, nothing was done until 1814, when, at great labor and expense, 20 tons were got down the river and were delivered in Philadelphia. Two years before this a few wagon loads had been received there from the Schuylkill mines; but the regular trade can hardly be said to have commenced until 1820, when the receipts in Philadelphia amounted to 365 tons. Such was the commencement of the great anthracite trade of Pennsylvania, which in the course of 45 years has been steadily increasing, till it now reaches the enormous amount of 15,368,437 tons for the year 1867, and sustains numerous branches of metallurgical and mechanical industry, the possible dependence of which upon this fuel and source of power was hardly dreamed of when its mines were first opened.

The existence of bituminous coal west of the Alleghanies was probably known as early as was that of anthracite in the eastern part of Pennsylvania; and on the western rivers it could not fail to have been noticed by the early missionaries, voyageurs, and hunters. In the old maps of 1770 and 1777 the occurrence of coal is noted at several points on the Ohio. A tract of coal land was taken up in 1785 near the present town of Clearfield, on the head-waters of the west branch of the Susquehanna, by Mr. S. Boyd, and in 1804 he sent an ark load of the coal down

The mineral coals are found of various sorts, which are distinguished by peculiarities of appearance, composition, and properties. Derived from vegetable matters, they exhibit in their varieties the successive changes which these have undergone from the condition of peaty beds or deposits of ligneous materials-first into the variety known as brown coal or lignite, in which the bituminous property appears, while the fibre and structure of the original woody masses is fully retained; next in beds of bituminous coal comprised between strata of shales, fireclay, and sandstones; and thence through several gradations of diminishing proportions of bitumen to the hard stony anthracite, the composition of which is nearly pure carbon; and last of all in this series of steps attending the conversion of wood into rock, the vegetable carbon is locked up in the mineral graphite or plumbago. These steps are clearly traceable in nature, and in all of them the strata which include the carbonaceous beds have undergone corresponding changes. The clayey substratum that supports the peat appears under the beds of mineral coal in the stony material called fire-clay (used when ground to make fire-brick); the muddy sediments such as are found over some of the great modern peat deposits, appear in the form of black shales or slates, which when pulverized return to their muddy consistency; the beds of sand, such as are met with in some of the peat districts of Europe interstratified with different peat beds, are seen in the coal-measures in beds of sandstones; and the limestones which also

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