brought from the coal mines of Missouri and Illinois, as the ores also can be carried to the river to meet there the fuel. The locality is already connected with St. Louis by a railroad. A blast furnace was built here in 1846, and another in 1855. A bloomary with six fires was started in 1850, and has produced blooms at an estimated cost of $30 per ton. Shepherd mountain, about a mile distant from the Pilot Knob toward the south-west, is composed of porphyritic rocks, which are penetrated with veins or dikes of both magnetic and specular ores. These run in various directions, and the ores they afford are of great purity. They are mined to work together with those of the Pilot Knob. The mountain covers about 800 acres, and rises to the height of 660 feet above its base. Other localities of these ores are also known, and the occurrence of specular ore is reported by the state geologists in several other counties, as Phelps, Crawford, Pulaski, La Clede, etc. In many parts of the United States and its territories iron is known to exist in great quantities. In Nebraska and Wyoming territory, near the line of the Union Pacific Railroad, large beds of iron ore of good quality are found; in proximity to extensive coal deposits, and these will be utilized for making rails of iron or steel for that great thoroughfare. In Kansas, Colorado, and New Mexico, are beds of specular and other ores in great profusion. The northern territories, as well as the Pacific States and territories, have abundant ores of the richest qualities, and coal enough and wood enough to melt them successfully. IRON MANUFACTURE. Iron is known in the arts chiefly in three forms-cast iron, steel, and wrought iron. The first is a combination of metallic iron, with from 1 to 5 or 5 per cent. of carbon; the second is metallic iron combined with to 14 per cent. of carbon; and the third is metallic iron, free as may be from foreign substances. These differences of composition are accompanied with remarkable differences in the qualities of the metal, by which its usefulness is greatly multiplied. The three sorts are producible as desired directly from the ores, and they are also convertible one into the other; so that the methods of manufacture are numerous, and new processes are continually introduced. The production of wrought iron direct from the rich natural oxides, was until modern times the only method of obtaining the metal. Cast_iron was unknown until the 15th century. Rude nations early learned the simple method of separating the oxygen from the ores by heating them in the midst of burning charcoal; the effect of which is to cause the oxygen to unite with the carbon in the form of carbonic acid or carbonic oxide gas, and escape, leaving the iron free, and in a condition to be hammered at once into bars. The heat they could command in their small fires was insufficient to effect the combination of the iron, too, with the carbon, and produce the fusible compound known as cast iron. In modern times the great branch of the business is the production of pig metal or cast iron in blast furnaces; and this is afterward remelted and cast in moulds into the forms required, or it is converted into wrought iron to serve some of the innumerable uses of this kind of iron, or to be changed again into steel. In this order the principal branches of the manufacture will be noticed. The production of pig metal in blast furnaces is the most economical mode of separating iron from its ores, especially if these are not extremely rich. The process requiring little labor, except in charging the furnaces, and this being done in great part by laborsaving machines, it can be carried on upon an immense scale with the employment of few persons, and most of those ordinary laborers. The business, moreover, has been greatly simplified and its scale enlarged by the substitution of mineral coal for charcoalthe latter fuel, indeed, could never have been supplied to meet the modern demands of the manufacture. Blast furnaces are heavy structures of stone work, usually in pyramidal form, built upon a base of 30 to 45 feet square, and from 30 to 60 feet in height. The outer walls, constructed with immense solidity and firmly bound together, inclose a central cavity, which extends from top to bottom and is lined with large fire brick of the most refractory character, and specially adapted in their shapes to the required contour of the interior. The form of this cavity is circular in its horizontal section, and from the top goes on enlarging to the lower portion, where it begins to draw in by the walls changing their slope toward the centre. This forms what are called the boshes of the furnace-the part which supports the great weight of the ores and fuel that fill the interior. For ores that furnace, the engines are of the most powermelt easily and fast they are made steeper ful kind, and the blowing cylinders are of than for those which are slowly reduced. great dimensions and strength. Some of The boshes open below into the hearth-the the large anthracite furnaces employ cylin'central contracted space which the French ders 74 feet diameter, and 9 feet stroke. One name the crucible of the furnace. The of these running at the rate of 9 revolutions walls of this are constructed of the most re- per minute, and its piston acting in both difractory stones of large size, carefully selected rections, should propel every minute 7,128 for their power to resist the action of fire, cubic feet of air (less the loss by leakage) and seasoned by exposure for a year or more into the furnace-a much greater weight than after being taken from the quarry. Being that of all the other materials introduced. the first portion to give out, the stack is built It is, moreover, driven in at a pressure (proso that they can be replaced when necessary. duced by the contracted aperture of the The hearth is reached on each side of the nozzle of the tuyeres in relation to the great stack by an arch, extending in from the out- volume of air) of 7 or 8 lbs. upon the square side. On three sides the blast is introduced inch. Two such cylinders answer for a pair by iron pipes that pass through the hearth- of the largest furnaces, and should be driven stones, and terminate in a hollow tuyere, by separate engines, so that in case of acciwhich is kept from melting by a current of dent the available power may be extended to wa'er brought by a lead or block-tin pipe, either or both furnaces. It is apparent that and made to flow continually through and the engines, too, should be of the largest class around its hollow shell. The fourth side is and most perfect construction; for the blast the front or working-arch of the furnace, at the is designed to be continued with only tembottom of which access is had to the melted porary interruptions that rarely exceed an materials as they collect in the receptacle pro- hour at a time, so long as the hearth may vided for them at the base of the hearth or remain in running order-a period, it may be, crucible. This arch opens out into the cast- of 18 months, or even 4 or 5 years. Furing-house, upon the floor of which are the naces were formerly built against a high bank, beds in the sand for moulding the pigs into upon the top of which the stock of ore and which the iron is to be cast. Upon the top coal was accumulated, and thence carried of the stack around the central cavity are across a bridge, to be delivered into the constructed, in first-class furnaces, large flues, tunnel-head or mouth of the furnace. The which open into this cavity for the purpose more common arrangement at present is to of taking off a portion of the heated gaseous construct, a little to one side, an elevator, mixtures, that they may be conveyed under provided with two platforms of sufficient the boilers, to be there more effectually con- size to receive several barrows. The moving sumed, and furnish the heat for raising steam power is the weight of a body of water let for the engines. A portion of the gases is into a reservoir under the platform when it also led into a large heating-oven, usually is at the top. This being allowed to descend built on the top of the stack, in which the with the empty barrows, draws up the other blast (distributed through a series of cast iron platform with its load, and the water is dispipes) is heated by the combustion. These charged by a self-regulating valve at the pipes are then concentrated into one main, bottom. The supply of water is furnished which passes down the stack and delivers the to a tank in the top either by pumps conheated air to the tuyeres, thus returning to nected with the steam engine or by the head the furnace a large portion of the heat of its source. which would otherwise escape at the top, and adding powerfully to the efficiency of the blast by its high temperature. The boilers, also conveniently arranged on the top of the furnace, especially when two furnaces are constructed near together, are heated by the escape gases without extra expense of fuel, and they furnish steam to the engines, which are usually placed below them. On account of the enormous volume of air, and the great pressure at which it is blown into the The furnaces of the United States, though not congregated together in such large numbers as at some of the great establishments in England and Scotland, are unsurpassed in the perfection of their construction, apparatus, and capacity; and none of large size are probably worked in any part of Europe with such The Siemen's regenof materials. erating furnace is adopted in those more recently built, wherever an intense heat is required for the reduction of the ores. economy WROUGHT IRON. It has been, in the past, a just ground of complaint against the producers of wroug at iron and steel, that they could not reduce either directly from the ore-but must go through the long and tedious processes of first making pig or cast iron, then eliminating the carbon from the cast iron by a still more tedious process to produce the wrought iron, and then restore a part of the carbon to make steel. It was said with truth that the half civilized Hindoo tribes and even the barbarous Fans of West Africa, made their native wrought iron (the wootz of India) directly from the ore of an excellent quality, and by a much simpler process than was adopted either in Europe or the United States. There has been, until within the past fifteen or eighteen years, a spirit strongly adverse to progress or improvement among iron producers. By their rude and wasteful processes and their adherence to traditional methods and tests, they succeeded in making a fair though not very uniform quality of wrought iron, at a pretty high cost, but they deprecated any change even if it were for the better. The philosophy and chemistry of iron-making were not well understood, and the time and way of its "coming to nature" a term which conveys the idea of a mystery, was a secret which could only be learned, it was thought, by some supernatural inspiration or some extraordinary skill, only to be acquired by long experience and careful observation. ganese, powdered charcoal, or spiegeleisen, or in some cases silica, to act as flux and remove the sulphur, phosphorus, or other impurity, and to destroy the excess of carbon. He knows, too, just what heat is requisite, and how long it must be continued to produce a certain result every time. Here is no guess-work, no “rule of thumb," no uncertainty. If he requires the best steel for rails, he can furnish it of precisely standard quality every time; if he is producing steel for the finest cutlery he can produce that; if he desires a wrought iron which shall be so tough and flexible that it can be bent double cold without any symptoms of flaw or crack, he knows just what percentage of the different ores, what eliminating processes, and what amount and duration of heat is necessary to produce it. Now, as in the past, there are different grades and qualities of cast iron, wrought iron, and steel, intended for different purposes, made from different ores, and possessing different degrees of tenacity, hardness, and ductility; but the iron-maker who cannot produce from a given ore, or ores, that description of iron which he desires, without failure, does not understand his business. Cast iron contains, according to the purpose for which it is intended, from five to six and a half per cent of pure carbon, either chemically or mechanically combined, and except the combination of iron with hydrogen, which is its normal condition, it is not the better for any admixture of other metals or elements, though for some purposes a small percentage of manganese, tungsten, or even a little silicon, are not disadvantageous. As a matter of practical fact, however, both sulphur and phosphorus are usually present, though in good samples in very small amount. By sufficient care they can be almost entirely eliminated, and are so in the best steel and wrought iron. The Bessemer process, invented and put in practice about 1852, first disturbed this popular idea; but in its earlier history this process was not entirely free from guess-work and the coming-to-nature theory by some sudden and unexplicable change; subsequent discoveries and experiments removed this mystery entirely, and there is not, to-day, in practical chemistry and metallurgy a more thoroughly- Steel, according to the purpose to which defined science than that of making iron is to be applied, contains, in chemical comThe iron master, who is fully educated for bination it is believed, from six-tenths to one his business, having before him an accurate and six-tenths per cent. of carbon, and should analysis of his ores, and knowing, as he can have no other ingredient. Wrought iron, if he will, that they are constant in their apart from its ordinary combination with composition, proceeds with the utmost cer- hydrogen, should be entirely free from sultainty to add other ores, or to permeate the phur, phosphorus, or silicon, and though for molten ore with atmospheric air, or to force some purposes, a little manganese, tungsten, additional oxygen through it by means of and a very small percentage of carbon may nitrate of soda, nitrate of potassa, peroxide not prove disadvantageous, yet practically a of iron, or other oxygen-yielding compound, pure iron is preferable to any alloy. Yet it or introduces a definite quantity of man- is seldom actually free from impurities. |