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MANUFACTURE OF IRON.

We shall take a short review of the different kinds of ore which the United States afford to the manufacturer.

a. Magnetic Oxide of Iron.-Black magnetic ore is found, in the State of New York, on Lake Champlain and Hudson River; in Vermont, at Bridgewater and Marlborough; in New Hampshire, at Franconia; in New Jersey and Pennsylvania, in large quantities; in Missouri and Wisconsin; and will doubtless be found in Oregon, California, and New Mexico. This ore is generally rich; and one ton and three-quarters to three tons of ore produce, on an average, one ton of metal. It very seldom affords cheap pig metal, on account of the expense of roasting it, and of working it in the blast furnace. If we want a good quality of pig metal from this ore, it must be carefully roasted, and under all conditions worked by cold blast in the furnace. By proper treatment, it affords the very best. and safest kind of bar iron; but by carelessness, or by an injudicious saving of fuel, very short, brittle iron. By careful roasting, and the cold blast, Sweden and Russia furnish excellent iron; but all experiments of raw mine and hot blast have, thus far, failed to produce from this ore a quality of iron favorable to the market. Where we want good bar or wrought iron, and are not too particular in relation to expense, this ore may furnish a solid foundation for a prosperous business.

b. The next in quality is the Sparry Carbonate of Iron. This is seldom found in the United States; it exists in Roxbury and Monroe, Conn., and Plymouth, Vermont, but in quantities too small to deserve particular attention. Spathic ore is the most expensive material from which iron is manufactured, on account of the various and expensive manipulations which the production of a good marketable article renders necessary; gray pig metal it will scarcely yield by any means, and the application of hot blast is so injurious to its quality, that all experiments have yet failed to make that modern improvement available. But by careful treatment of the ores, cold blast in the furnace, and proper manipulation in the forges, this ore yields a bar iron unsurpassed in strength, and furnishes steel with extraordinary facility.

c. Specular Iron Ore.-This class, so far as we are acquainted with the deposits of iron ore, is very scarce in the United States. In Massachusetts and New York, there is hardly any worth mentioning; but according to the geological formations of Iowa, Missouri, Arkansas, Texas, Oregon, California, and New Mexico, these States ought to contain specular ore. This ore is, in many respects,

the most valuable of any; for its application is very simple, and the iron it yields is the strongest and most tenacious kind known in the world. Where it can be bought at reasonable prices, it may be considered the most advantageous for the individual manufacturer.

d. Hydrated Oxide of Iron.—This class, together with the mineral coal deposits, constitutes to the present generation, and will constitute, in a far greater degree, to future generations, a solid foundation of wealth, comfort, and happiness. Upon this ore the citizens of our vast republic may safely base their hopes of continual prosperity; its sources are inexhaustible, and its quality of such a nature, that it constantly requires the mental and physical exertions of the manufacturer of iron. Improvements in arts and sciences are applied with advantage to this branch of the natural deposits, because the material varies greatly in different localities. Constant industry alone will enable us to gain the advantage over difficulties so unceasing. But this ore is the only source of cheap iron; and by the employment of charcoal, it yields iron even of good quality.

The body of this ore may be divided into two geological classes; one class belongs to the primitive and transition rocks, and the other to the tertiary and more recent deposits. The first is generally of better quality than the second; but no definite rule can be given in relation to them. Nearly every State in the Union is abundantly supplied with this kind of ore. From Maine to New Jersey, ore of the older formations abounds; but from New Jersey to Alabama, and from Western New York and Ohio to the Mississippi, within and around the great coal formations, the great class of the hydrates, with the exception of the compact carbonates, alone is to be found. On the working of this ore in the furnaces and forges, we shall speak in the proper place; we shall confine our attention at present to its price. It is generally found in large bodies or regular veins, for which reason the working or raising of the ore is cheap. Where this is not the case, it is best not to commence operations. If an amount of ore sufficient to produce a ton of iron exceeds seven or eight dollars at the furnace, it is evident that competition against those works which pay almost nothing, or, as in Pennsylvania, Ohio, Tennessee, pay but from one to one dollar and a half per ton for iron, would be unsafe. Prosperous times, and a healthy market, may enable us to endure such prices; but when the reverse is the case, a business cannot safely be conducted. Cheap fuel and local facilities, however they may lessen this disadvantage, are not sufficiently strong to overcome a difference of six dollars in favor of

cheap ore; and it is, at least for the beginner, doubtful whether an establishment based upon expensive ore will prosper. Above all things, it is necessary that those who intend to start on a new locality, should take counsel from experienced men as to the quality and richness of the ore; and should the ore happen to average a given quantity of iron, and should the price of an amount of ore sufficient to yield a ton of iron, be but six dollars, the business may be attempted, and may, with industry and care, be successful. However profitable local advantages and good times may make the iron business, to those who find themselves surprised by a sinking market and limited means the losses are great. Against this danger, good quality of the product is the safest guard; and if to this advantage, that of cheap ore can be united, most difficulties can be successfully met.

e. The Compact Carbonate-Argillaceous Ore of the Coal Formation.-This ore is very abundant in the large western coal fields, and will be a source of iron so long only as the out-crops of this ore which are oxidized, and hydrates can be wrought at reasonable prices; the mining of this kind of ore cannot be considered a safe business, for the raising is generally very expensive, and the roasting and smelting difficult. But where it can be raised at one dollar per ton, as in some localities on the Alleghany River; and where the quality of iron is of no consideration, it may serve as a source of cheap iron, and therefore be considered valuable. But we must warn those who are not acquainted with the working of this kind of ore, that they will generally experience difficulties which are very apt to absorb means which, to enterprising individuals, are exhaustive. We shall refer to this subject again in another chapter.

The remaining kinds of ore are of so small amount as not to require particular attention. Where favorable localities offer themselves, an enterprise based upon such ores may be hazarded, but with due consideration of price and market; for iron manufactured from such fancy ores is generally of an inferior kind.

XX. Mining of Iron Ore.

The mining or digging of iron ore does not differ much from other mining operations; and therefore a general description of the mining operation might suffice in this particular case. However, we shall endeavor to present a clear view of the subject.

Mining is an art; "it is a highly cultivated mechanism," says Andrew Ure. Where science and art have liberally spent their

means, architecture, machinery, and plastic arts impart instruction, through the medium of the eye, to the mind, by the display of their respective masterpieces. But this is not the case in the art of mining. An adequate idea of the high cultivation to which this branch of skill and industry has been brought cannot be exhibited at one view, because there is no one point of view from which any other art can be completely sketched. The subterraneous structures present some of the most interesting monuments of the genius of the human mind. Cultivated, for many centuries, under the guidance of science and industry, they are not, and cannot be, however great and ingenious, the objects of panoramic representation. The philosophical mind alone can contemplate and survey them, either in whole or in detail. And therefore those marvellous regions, in which roads, often many miles long, are cut and highly perfected, are unknown to the mass of the people, and disregarded by men of the world. When chance, curiosity, or interest induces such to descend into these dark recesses of our world, they merely discover a few insulated objects which make a vague, indefinite impression on their minds but the symmetrical disposition of the minerals, and the laws which govern geological phenomena, which serve as guides to the skilful miners, they cannot recognize. From exact plans of the underground workings alone can a knowledge of the nature, extent, and distribution of the useful minerals be acquired.

Among the great variety of minerals, apparently infinite, which compose the crust of the earth, science has demonstrated the prevalence of a few general systems of rocks, to which appropriate names have been given. The more recent deposit, or loose gravel and earth, is called alluvium; the more ancient deposit of this kind, diluvium; below this are the secondary rocks; the next, transition rocks; and the oldest, or lowest rocks, primitive formation, or primitive rocks. Every mineral deposit forms more or less of a plane, with distinct direction and inclination; the former is the point of azimuth or horizon towards which it dips, as north, south, southwest, &c.; the latter is the angle which it forms with the horizon. The direction of the mineral deposit is that of a horizontal line, drawn in its plane. Hence, the lines of direction and inclination are at right angles to each other.

Masses are mineral deposits not extensively spread in the form of planes-mere regular accumulations, rounded, or spheroidal. Masses generally occur in the primitive rocks.

Nests, Concretions, or Nodules, are smaller or larger masses of

minerals found in stratified rocks, often kidney-shaped, tuberous, round, or spheroidal.

Large veins are called lodes; they are seldom parallel on their opposite surfaces, and sometimes terminate like a wedge; their course often varies from that of the strata in which they lie. Lodes sometimes pursue for a distance the space between two contiguous strata, and then divide into several branches. Lodes of iron ore are found in almost every geological formation.

Veins are small lodes, which often traverse the strata of the transition rocks, but generally run parallel in the coal measures and more recent formations.

Iron ore is met with in all the different geological eras. Among the primitive rocks, we find magnetic ore and specular iron, chiefly congregated in masses or beds, sometimes of enormous size; as, for instance, the magnetic ore on Lake Champlain. In transition rocks, we find hematite and sparry iron ore, generally in veins or lodes; seldom in masses. In the coal measures, we find brown iron ore and yellow iron ore in all varieties, globular and kidney-shaped oxide, and compact carbonate, generally in veins of greater or less extent. Alluvial and diluvial iron ores are the clay ores, granular ores, bog or meadow ore, &c. The ores which belong to the primitive period always have a metallic aspect, bright lustre, and furnish the richest and purest iron. The ores of the transition rocks furnish less iron, but it is generally of the most profitable kind. The more recent the age of ores, the poorer they are, until, becoming more and more earthy, they form alluvial soil.

An acquaintance with the general results, collected and classified by geology, must be our guide in investigations of mining. This enables the observer to judge whether any particular district contains iron ore, or where this ore can be found. For want of such knowledge, many persons have gone blindly into researches which were, in their nature, absurd and ruinous. Geology teaches us that in primitive rocks no stratified veins can be found; neither bog ores, nor fossil, nor calcareous ores. Transition rocks contain veins of hematite, spathic iron, specular iron, &c., but the veins run either between two different strata, as jura lime and mica slate, or traverse the strata at indefinite angles. The coal measures generally contain iron ore, but no magnetic ore, spathic iron, specular iron, or brown hematite. We must be satisfied with the poorer hydrates resulting from the decomposition of the compact carbonates, or the decomposition of limestone and the carbonates themselves.