From many points of view the iron trade looks amazing, and drives the mind to admiring contemplation. If one considers that nature never completes its formation, while "gold, silver, and copper are found in their perfect state in the clefts of rocks, in the sides of mountains, or the channels of rivers," the peculiarity of the character of iron will in some measure be appreciated. Gold, silver, and copper, owing to their being already prepared in nature's furnaces and by nature's transmutations, were the metals first known and first applied to use; "but iron, the most serviceable of all, and to which man is most indebted, is never discovered in its perfect form; its gross and stubborn ore must twice feel the force of fire, and go through two laborious processes, before it becomes fit for use." And even the produce is only pig-iron, another series of nice processes being requisite before it has been converted into bar-iron. If we confine our reflections to the serviceableness of this metal, it will soon be perceived that it is so essential to the welfare of man that without it even his civilization could not be developed to any admirable extent; and that his comforts and occupations would then alone depend upon what the animal creation furnished, or such rude implements as could be made out of wood, stones, bones, or the softer metals. Even then what sort of implements would these be, if not subjected to the agency of iron tools, and rendered sufficiently available by means of the appliances of the same smelted metal?

If we come to Britain, the great iron furnace, and the most wonderful iron shop in the world, we shall find cause for unbounded admiration, and feel that our triumphs are not yet completed, or at their highest figure. Who in imagination can set limits to future achievements in this single department? and who can foretell what other changes and enlargements will accompany improvements in the production of iron? The fact is, that these improvements are stimulants to advancement in every line of life, be it that of agriculture, merchandize, or manufactures. Behold our implements of husbandry as compared with what they were fifty years ago! Think of our machinery in every trade! Reflect but for a moment on our steamers, whether by land or water; and then will arise trains of thought which must not only lead to some adequate con. ceptions of the importance of iron, but to feel that the subject is transcendent.

Look at our iron trade as it has advanced recently. In 1740 the amount of this precious article, as manufactured in England and Wales, was 17,350 tons. In 1788 the quantity was 61,300 tons. By 1796, and including Scotland, it had risen to 125,075. The rate advances with accelerated and ever accelerating speed. In 1806 the total produce was 268,206 tons. About twenty years afterwards it was 581,367 tons; and in 1828 it had reached 703,184.

But the next stride exceeds everything, not merely as regards quantity, but ratio; for in 1839 it had arisen to the enormous amount of 1,347,790 tons! Compare this with the produce one century earlier; and then say what may be the increase of produce during the next hundred, or even the next ten years.

We again shift our ground in order to obtain some glimpses of the successive operations by which the stubborn ore is transmuted into iron. What is called roasting first takes place, the process by which the gross ore is cleared of much of the foreign matter and several of the qualities of its native state, such as moisture and various intractable things, so that it comes to a condition to be pulverized. The next grand process is to smelt the pulverised ore; that is, by extreme heat to bring it to a state of fusion; when, by a variety or a detail of operations, the metal sinks and the scoria floats; after which the separation by discharges and flowings off is obtained, and pig-iron is the result. But before "bars" can be produced, a third series of operations is had recourse to, in order to refine the "pigs," and which are thus described :

"For this purpose a furnace is made use of resembling a smith's hearth, with a sloping cavity sunk from ten to twelve inches below the level of the blasting pipe. This cavity is filled with charcoal and scoria; and on the side opposite to the blast-pipe is laid a pig of cast-iron, well covered with hot fuel. The blast is then let in, and the pig of iron being placed in the very focus of the heat, soon begins to melt, and as it liquifies runs down into the cavity below; here, being out of the direct influence of the blast, it becomes solid, and is then taken out and replaced in its former position, the cavity being then filled with charcoal; it is thus fused a second time, and after that a third time; the whole of these three processes being usually effected in between three and four hours. As soon as the iron has become solid, it is taken out and very slightly hammered, to free it from the adhering scoria; it is then returned to the furnace, and placed in a corner out of the way of the blast, and well covered with charcoal; where it remains till, by further gradual cooling, it becomes sufficiently compact to bear the tilt-hammer. Here it is well beaten till the scoria are forced out; and it is then divided into several pieces, which by a repetition of heating and hammering are drawn into bars, and in this state is ready for sale. The proportion of pig-iron obtained from a given quantity of ore is subject to considerable variation from a difference in the metallic contents of different parcels of ore, and other circumstances; but the amount of bariron, that a given weight of pig-metal is expected to yield is regulated very strictly, the workmen being expected to furnish four parts of the former for five parts of the latter; so that the loss does not exceed 20 per cent."

The conversion of pig-iron into steel demands a word. This substance, which is a compound of iron and carbon, but in less proportion than that of pig-iron, is of such distinguished importance in most of the arts, that no other substance could be substituted,

capable of supplying its united properties of hardness, tenacity, and elasticity. After the pig-iron is totally deprived of carbon, and becomes malleable, the metal can be re-impregnated with that substance to a certain extent, without losing much of its malleable property.

It is curious to remark, that although we have made iron of excellent quality in this country, for all the nice purposes to which it is capable of being applied, yet in attempting to convert it into steel we have always failed. Of late, however, it has been so great a desideratum to obtain this article from British ore, that many efforts have been made to bring about this desirable object, and not altogether without success. We may yet entertain a hope, therefore, that the time will arrive when we shall not be dependent on other countries, especially Sweden, where the steel on which perfect reliance can be placed is produced.

It appears that the good qualities of steel,—and they are very numerous, depend upon circumstances partly chemical and partly mechanical, which have hitherto defied analysis. It is not even precisely known whether the union of iron and carbon is a chemical or mechanical union.

In consequence of this ignorance as to what constitutes the essential qualities of good steel, the processes by which favourable results have been obtained have in nearly all cases been empirical, and in many instances have been real or pretended secrets. The processes are of a nature to forbid any very nice calculations, and they are liable to great and unappreciable modifications in the execution. The hammering, alone, on which many of its good properties depend, is obviously an operation which cannot be meted out with very scrupulous nicety, and is besides liable to be very much influenced by the temperature of the metal and by the direction of the blows in reference to the mechanical structure of the mass.

In the last edition of the Encyclopædia Britannica, from which we have borrowed parts of our information, we find it also stated that steel being most frequently made from rolled bars of good, by which is meant pure iron, it is necessary, in order to communicate the desired quantity of carbon, that the bars be formed into bundles, and be placed in a large stove or furnace alternating with layers of carbon (hard-wood charcoal is preferred), and that a high temperature be maintained for a week or ten days, during which the iron gradually absorbs the required quantity of carbon, and becomes converted into steel. The completeness of this conversion is judged of from time to time by the examination of certain of the bars, which are so disposed as to be accessible for this purpose. If the carbon has not penetrated to the centre of the metal, this will be evident from the breaking of the bar transversely. Towards the end of the process, the watching requires to be skilful and constant,

because if the absorption of carbon becomes very excessive, the metal may be rendered so fusible as suddenly to melt. In any case the surface of the bars becomes so nearly in this soft condition that it is always blistered by the escape or rarefaction of air or gas from the interior of the metal; and hence bars so prepared have acquired the name of blistered steel. We shall not trace the processes of the manufacture further, having indicated some of its niceties and varieties, but conclude our notices of steel in the words of the Encyclopædia, that its destination" is of great importance in estimating even the theory of those processes, as may be well supposed, when it is recollected that a lancet will fracture almost like glass, while a bricklayer's trowel is required to cut the most refractory lump of semi-vitrified clay in the shape of brick. These two instruments are perhaps at the extremities of the scale, the perfect hardness and brittleness of the lancet contrasting with the extraordinary toughness and tenacity of the trowel."

Let us attend for a little to the improvements which have taken place in Britain as regards the processes of the manufacture of iron, The fuel employed for the purpose of melting and refining into malleable bars had always been charcoal; and to this day, perhaps, the same sort of material might have been exclusively used in this country could it have been obtained. But wood became scarce with us as the inhabitants increased, and, therefore, so far back as Elizabeth's reign, enactments were framed to regulate the consumption of wood when converting it into charcoal " for the making of iron." These prohibitions drove the iron-manufacturers to think of a substitute, and coal was resorted to, and a variety of experiments made with it, but for a number of years without success; so that the trade declined even from its primitive condition. One of the great difficulties was to command an adequate power of blast to act upon a comparatively obdurate mineral, while charcoal was easily affected by a simple and feeble bellows. At length, however, steam-engines, even in their infant state, were found to possess the requisite power when applied to improved and improving machinery. These engines, about the year 1760, were by Smeaton made so to operate upon a cylinder that a mighty blast-power was obtained, and now a furnace could yield nearly four times as much iron weekly as it had done before. At last came Watt, when his intuitive and mastering genius introduced such mighty improvements of the steam-engine that the most refractory ores were forced to yield what they contained of metal, while the richer gave up whatever they possessed. Various concomitant advancements were realized in every stage of the manufacture of iron. One of these is called "puddling," which has ever since been so advantageously employed in producing, by means of coal, the malleable material. This is the account given of the process:

"A common reverberatory furnace, heated by coal, is charged with about two-and-a-half hundred weight of this half-refined grey iron. In a little more than half an hour the metal will be found to be nearly melted: at this period the flame is turned off, a little water is sprinkled over it, and a workman, by introducing an iron bar, or an instrument shaped like a hoe, through a hole in the side of the furnace, begins to stir the half fluid mass, and divide it into small pieces. In the course of about fifty minutes from the commencement of the process, the iron will have been reduced by constant stirring to the consistence of small gravel, and will be considerably cooled. The flame is then turned on again, the workman continuing to stir the metal; and in three minutes' time the whole mass becomes soft and semi-fluid; upon which the flame is again turned off. The hottest part

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of the iron now begins to heave and swell, and emit a deep blue lambent flame, which appearance is called fermentation; the heaving motion and accompanying flame soon spread over the whole, and the heat of the metal seems to be rather increased than diminished for the next quarter of an hour after this period the temperature again falls, the blue flame is less vigorous, and in a little more than a quarter of an hour the metal is cooled to a dull red, and the jets of flame are rare and faint. During the whole of the fermentation the stirring is continued; by which the iron is at length brought to the consistency of sand; it also approaches nearer to the malleable state, and in consequence adheres less than at first to the tool with which it is stirred. During the next half-hour the flame is turned off and on several times; a stronger fermentation takes place; the lambent flame also becomes of a clearer and lighter blue, the metal begins to clot, and becomes much less fusible and more tenacious than at first; the fermentation then, by degrees, subsides, the emission of blue flame nearly ceases, the iron is gathered into lumps, and beaten with a heavy-headed tool. Finally, the tools are withdrawn, the apertures through which they were worked are closed, and the flame is again turned on in full force for six or eight minutes. The pieces being thus brought to a high welding heat, are withdrawn and shingled; after this they are again heated, and passed through grooved rollers, by which the scoria are separated; and the bars thus forcibly compressed acquire a high degree of tenacity."

We need not, for the purpose of showing to the reader who may be the most slightly conversant with mechanical science, or with the history of the marvellous strides which in Britain have been achieved in manufactures, whether of pliant cotton or intractable ores, enumerate even the principal improvements in our iron trade. The prodigious amount of metal which is now produced, and the rates of increase, as we have already stated them, even since the year 1830, are facts that are sufficiently significant for our general and popular purpose. It would be easy to render prominent in any hasty glance at improvements, the invention of machinery that now performs the office of hammering, but which was wont to be done by hand-labour. Or, were we to describe the introduction of the hot instead of the cold blast, and the advantages of the substi