of nodules of irregular masses. It is common in beds of spathic iron, in Styria and Carinthia, and generally associated with other ores of iron or earthy minerals, as epidote, hornblende, augite, calcareous spar, and quartz.

All the red clays belong to this class, and, when they contain more than 20 per cent. of metal, may be considered an ore of iron.

d. Hydrated Oxide of Iron, Brown Oxide of Iron, Brown Iron Stone, Hematite.-We have here a class of iron ores which in quantitative importance, supersede any other kind in the United States. Hydrated oxide of iron always affords a yellow powder, without any shade of red, sometimes brownish, or even velvet black. At the blowpipe it turns brown or red, and in the reducing flame black, and melts into a black cinder. Burnt or roasted, it is strongly attracted by the magnet, but not in its raw state. Calcined, it yields a red powder, oxide of iron, and is employed for the same purposes as the oxide. The yellow or brown varieties. contain a large admixture of water in chemical combination, and hence they are called hydrates.

Hydrated oxide of iron consists, in 100 parts, of

59.15 iron

26.15 oxygen

14.70 water

100.00 hydrated oxide of iron.

Brown or yellow iron ore, therefore, never contains more than 59.15 lbs. of iron in 100 lbs. of ore.

The mineralogical term of this ore is Limonite; it comprises a great number of compound varieties. Its forms are various-globular, reniform, stalactitic, and mamillary. It presents great variety of surface, being smooth, granulated, reniform, drusy, columnar; and it is often an impalpable powder. It is a species which, on account of differences in regard to mechanical composition, has received a great diversity of names; still, all the varieties are of the same chemical composition, unless adulterated by foreign matter. The whole class is the result of the decomposition of other iron compounds, namely, iron pyrites, carbonates, red oxides, sulphates, &c. The fibrous limonite, or brown hematite, contains sometimes beautiful crystals of the hydrate, and is known under the name of pipe ore, brown ore, and shell ore; it is then reniform, and consists of alternate layers of different color, or coats of different hardness. To this species belong also a great variety of impalpable and scaly compounds.

Limonite occurs in beds and veins, generally accompanied by spathic iron, calcareous spar, aragonite or quartz. We find these beds, or veins, both in ancient and secondary rocks, in tertiary deposits, in diluvium, and alluvium. In the older rocks, limonite is generally derived from pyrites, and in the coal measures from carbonates; we find it in globular masses imbedded in clay, in sandstone, and in bogs.

Limonite is very plentiful all over the globe, particularly in the United States; vast beds are near Salisbury and Kent, in Connecticut, resting in mica slate; they are of the best kind of brown hematite, and are fibrous. In the State of New York, near Beekman and Amenia, are similar deposits. Massachusetts is favored with that kind of ore; also Vermont, Maryland, and Ohio. The whole iron business of Hanging Rock depends upon it. Kentucky, Tennessee, and Alabama, abound in inexhaustible beds of the best quality. But above all, Pennsylvania has the richest varieties of this kind. No doubt there is more in the United States than we at present know of, and the great valley between the Rocky Mountains and the Alleghanies is a natural basin for all such valuable deposits swept down from Canada, and the impenetrable north.

Limonite is the main source of the iron of commerce all over the globe. It affords an easy and cheap material, and the better varieties are excellent iron; but we have to be careful in the selection of the ore beds. The eastern ore is generally of prime quality; so is that of Hanging Rock in Ohio; that of Tennessee and Alabama is of as good a quality of this kind as one could desire; but the deposits of the coal formation, the pipe ores, and bog ores, are to be carefully selected in reference to quality. This kind of ore in the older rocks is generally good, but where it is derived from more recent deposits, it contains some of the original matter from which it is decomposed. The pipe ore is decomposed sulphuret, and frequently we find a core of pyrites in the centre; then the ore furnishes hot-short iron; but, carefully roasted, the sulphur of the pyrites can be mostly evaporated. The hydrates of the coal formation are mainly derived from spathic iron, and frequently contain carbonic and sulphuric acids, which impair the quality of the metal, but can be removed by a careful roasting of the ores. Bog ores, which mostly contain phosphoric acid, are, for the manufacture of pig metal, incurable, for the phosphorus cannot be separated by roasting; but this separation can be effected in the forge, and hence, deserves consideration. In the main, this kind of ore furnishes an

excellent material in the blast furnace, yields cheap pig metal, and of all classes of ore is the most available for improvement in the forge-as well in the charcoal forge as in the puddling furnace.

III. Carburets of Iron.

Iron has a great affinity for carbon, but science has yet done very little towards investigating the nature of the different compounds. In the chemical laboratories, carburets of iron are generally made by decomposing in a high heat the salts of iron of the vegetable acids; we obtain in that way various compositions, whose nature is not investigated. Those compounds of iron and carbon deserve more attention on the part of scientific men than has yet been paid to them. The investigations of such men would enable us to understand the nature of pig metal better than we do at present.

Some ores, of which we are at present ignorant, may belong to the class of carburets; they are certainly not found in the older rocks, but from the period of the coal measures to the present we may expect to find them. We are not aware that there are any employed in the United States in the manufacture of iron, but, where such can be found they deserve to be employed. In Scotland, the whole iron business depends mainly upon this kind of ore; there it is called Blackband, and was first made use of by Mr. Mushet at the commencement of the present century. After encountering great opposition, this ore enables Scotland to be master in every pig iron market which she can supply.

Carburets are black, sometimes grayish, of slaty appearance, more or less hard, but always harder than clay slate; the powder is attracted by the magnet, and turns brown or red by being calcined. Some varieties burn in larger heaps without other fuel; others have to be calcined, by adding coal or wood. Foreign matter is almost always mixed with the ore; these admixtures are mainly silex or clay. Frequently this ore is classed with the magnetic oxide, on account of its black color; but it is soluble in sulphuric acid, and with the escape of hydrogen leaves carbon, which distinguishes it from the black magnetic ore.

In the coal deposits of Frostburgh (Md.), this ore is found of an inferior quality; it generally contains but from 20 to 25 per cent. of iron. It is also found in small quantities in the Pittsburg coal formation.

This ore deserves the attention of the iron master; for, if even

poor, it always furnishes good pig metal, and is, after being well roasted, an excellent material in the blast furnace: it is more inclined to make gray foundry iron than any other ore; besides that, it works exceedingly well in the furnace.

IV. Sulphurets of Iron.

Iron has a very great affinity for sulphur, and we are acquainted with five definite compounds. It is very difficult to separate iron from sulphur by heat alone. Of the five different compositions, two only deserve our attention-the white and the yellow sulphurets.

a. White Sulphuret of Iron. White Pyrites abound in coal beds, and in the accompanying strata of clay; also in regular veins along with ores of lead, copper, and iron, in the transition rocks. They are very common all over the globe; and are found in New York, Massachusetts, Connecticut, Ohio, and other States. Before the blowpipe, sulphuret of iron becomes red; upon charcoal, the sulphur is evaporated, and oxide of iron remains; it is very liable to decomposition. It is preferable to the yellow kind in the manufac ture of copperas, and is, in coal mines, the most dangerous of any, for it often decomposes so quickly as to kindle the coal slack. Therefore, where it is frequently met with in coal mines, great cleanliness and order ought to be practiced. Its composition is, in 100 parts, 45.07 iron

53.35 sulphur

0.58 manganese

99.00 white pyrites.

b. Yellow Sulphuret of Iron. Yellow Pyrites.-This variety becomes red before the blowpipe, like the above; in the reducing flame it melts into a globule, which continues red-hot for a short time, and possesses, after cooling, a crystalline appearance. In nitric acid, it is slowly soluble with the precipitation of sulphur, but in no other acid. It is composed of

47.30 iron

52.70 sulphur

100.00 yellow sulphuret of iron.

Yellow pyrites is almost identical with the white pyrites, and the latter appears to be only different in containing more foreign matter. Both are widely diffused among the ores of iron. We find such in

massive nodules, crystals, and veins, in the coal beds, clay slate, graywacke, greenstone, limestone, and in beds in primitive slate. It is the main material which is used for manufacturing copperas, alum, oil of vitriol, and Spanish brown, sulphur, and sulphuric acid. In the United States, we find iron pyrites in Vermont, New York, Ohio, New Jersey, Pennsylvania, Maryland, and, in fact, more or less in every State.

This class of iron compound does not belong to the iron ores proper, but its immense quantity, and its presence in coal beds, require especial notice, on account of the injurious effect it has upon the quality of iron, where it comes in contact with the ores or coal. The presence of pyrites is generally indicated by its sulphurous smell, either in roasting the ore or in the casting house; and when such indication is manifest, the careful roasting of the ores, and the long exposure of the roasted ore to the atmosphere, are the best methods of removing the sulphur. If the main body of sulphur is found to be in the fuel, there is little hope of getting rid of it, for it cannot be entirely expelled where a surplus of carbon is present, as is the case in caking coal.

V. Phosphurets of Iron.

Phosphorus combines readily with iron; the compound is whiter than iron itself, can be beautifully polished, but is very brittle, cold-short. Native phosphurets are very seldom found, and we allude to them because the presence of phosphorus in the pig metal occasions it to be cold-short. Under the head of phosphate of iron we shall speak of the ores belonging to this class.

VI. Arseniurets of Iron.

A native compound of iron, arsenic, and sulphur, is called mispickel, or, if it contains silver, which is often the case, it is denominated argentiferous arsenical iron. Arsenic and iron have considerable affinity, and in smelting combine readily; the composition is brittle, not magnetic. Mispickel is white, hard, of a vitreous lustre; it emits before the blowpipe arsenical fumes, and leaves a sulphuret of iron and arsenic soluble in nitric acid, and is composed of 36.04 iron 42.88 arsenic

21.08 sulphur

100.00 mispickel.