The first quality, or best king and queen iron, is thus prepared :—a ball or faggot, being duly heated, is first compressed a little by the squeezer, then rolled to a flat bar in the shingling rolls ; the bar is next cut into pieces, piled, re-heated, and made into a beat bloom under the shingling hammer. This best bloom is next re-heated, passed through the roughing rolls, and then through the finishing rolls, whereby it is brought to the form required. It is an important consideration, that much of the old iron used in the re-manufacturing process was originally the " best " iron of the first manufacturer ; and that as the greater part of the old iron has been improved at the blacksmith's forge, it may safely be said, that where the processes of refinement of the first manufacturer leave off those of the re-manufacturer begin: and as it is universally admitted that the more iron is worked, the better it becomes, (which is indeed proved by the extreme tenacity of fine iron wire,) it seems to follow, that the re-manufac tured iron we have been describing must be greatly superior to that which is newly made from pigs, however carefully the process may have been conducted, or however often it may have been repeated.
.Raesims and Swedish Irons, which were formerly usually employed in our iron manufactures, are still applied extensively at Sheffield and some other places, in the fabrication of the superior kinds of steel and fine cutting instruments ; but their application to other purposes is extremely limited, on account of their much greater cost than our own best charcoal iron, which is scarcely inferior for most purposes to which bar iron is applied. The Russian and Swedish irons are entirely converted and refined with charcoal by processes so similar to our own as not to need description. These valuable foreign irons are more particularly noticed under the sub-head Steel in this article.
Malleable Cast-iron. A very extensive manufacture of iron articles is now carried on at Birmingham, Sheffield, and other places, which although are cast from fluid metal, are nevertheless malleable. This property is derived from two causes ; first, the pigs are prepared from the rich and pure iron ores of Cumberland ; and the metal thus obtained is combined with but a small quantity of carbon, so as nearly to resemble steel in colour, hardness, and the brilliancy of its fracture; and it has in consequence been designated by some manufacturers, run steel. An infinite variety of articles, including nails, saddlers' ironmongery, (and particularly as afterwards receive another metallic coat, as those which are p upon steel,) are cast from this metal. The castings thus produced are exceedingly brittle ; but this property is entirely destroyed by a process termed annealing, in which the i metal is deprived of the carbon to which its previous fusibility was owing, and is in consequence brought to that state of wrought iron requiring only the operations of the shingling forge and rollers to give it a laminated and fibrous texture. Nails made by this process may be drawn out longer, and bent backwards and forwards, without breaking. The metal is however not so strong or tough as hammered and rolled iron ; the discovery of the process is nevertheless of great value, as many excellent articles are produced in conse quence, which would not without it be made at double the cost. The discoverer of this mode of converting cast-iron goods into malleable, was Mr. Samuel Lucas, of Sheffield, who took out a patent for it in 1804 ; the specification of which we shall annex, as there are some manufacturers who, while they avail themselves of Lucas's process, assume it to be their own discovery, in conse quence of making some unimportant variations. " I declare that my said invention of separating the impurities from crude or cast-iron without fusing or melting it, and of rendering the same malleable and proper for the several purposes for which forged or rolled iron was used, and also, by the same method, of improving articles manufactured of cast-iron, and thereby rendering cast or crude iron applicable to a variety of new and useful purposes, is thus to be performed i—the pig, or cast-iron, being first made or cast into such form as may be most convenient for the purpose intended, it is to be put into a steel converting, or other proper furnace, together with a suitable quantity of iron stone, iron ore, some of the metallic oxides, lime, or any combination of these, (previously reduced to powder, or into small pieces,) or with any other substance capable of combining with, or absorbing the carbon of crude iron. A degree
of heat is then to be applied, so intense as to effect an union of the carbon of the cast-iron with the substance made use of, and continued so long a time as shall be found necessary to make the cast-iron either partially or perfectly malleable, accor ding to the purposes for which it may be wanted. If it be intended to make the iron perfectly malleable, from one half to two-thirds of its weight of iron stone, iron ore, or other substance, will be found necessary ; if only partially so, a much less quantity will be sufficient. Five or six days and nights will in general be found sufficient, during which to continue the heat, which towards the close of the process cannot be too great. Care should be taken that the pieces of cast-iron be not of too great thickness, as it would have the effect of length ening the process. But the proportion of the several substances made use of, and the degree and duration of the heat to be applied, must greatly depend, not only on the nature of those substances, but also on the nature and quality of the pig or cast iron employed, a knowledge of which can be obtained only by experience. The cast-iron to be rendered malleable, and the substances to be made use of for that purpose, may be placed in the furnace en alternate layers ; and in order to prevent the iron stone, or iron ore from adhering to the iron, a thin layer of sand may be placed between them. For the improvement c f articles manufac tured of cast-iron, the same directions may beobserved; except that when the articles are small, a less proportion of the substances for producing malleability will be required, and also a less degree and continuation of the heat." Steel. We place this well known invaluable substance under the head of iron, in preference to its own initial letter, considering that we may, with far more propriety, class it under that denomination than cast-iron; for the latter, which every body maintains to be iron, contains more foreign matter than steel, and of the very same kind; cast-iron containing about 7 per cent. of carbon or other matter, and steel considerably less than one per cent. ; even so little in some specimens, as a four-hundredth part. Steel is besides so much like malle able iron, in density and hardness, that few persons, comparatively speaking, know how to distinguish one from the other. The difference between common steel and common cast-iron we understand to be this; that steel is a very com pact and nearly pure iron, rendered more dense and bard by an intimate com bination with a minute portion of carbon, with which in some specimens is found manganese and silex ; and that cast-iron is a less dense and very impure iron, combined in an almost granulated state with a large proportion of carbon and other matters. We are supported in this view of the subject by the fact that in the manufacture of steel with bar iron and charcoal, by the process called cementation, the iron is increased in its specific gravity ; but if the pro cess of cementation be continued beyond the proper limits, the iron will absorb more and more carbon, until it becomes disintegrated, and runs down into cast iron, the loose texture of which is indicated by its greatly reduced specific gravity.