THE MANUFACTURE OF STEEL.
Steel is produced from iron, direct from the ores, by extracting a portion of the carbon from cast iron, or by adding carbon to malleable or bar iron. It is simply a compound of carbon and iron, as cast iron is; but cast iron contains from one to five per cent. of carbon, while steel contains only from a half to one per cent. of carbon. The best steel known to the cutlers of England and the sword makers of Damascus is produced by the wootz manufacturers of India, whose opera tions have been conducted since the days of Alexander, or perhaps before the birth of Brahma. (?) Steel can be made in the Catalan forge in small quantities, by using less ore and more charcoal, and simply raising the tuyer to prevent the blast from burning the car bon from the loup; but the steel so produced is very variable: sometimes a bloom of excellent steel may be produced, hut more frequently it may contain too much carbon, and be simple "pot-metal" or cast iron; or too little carbon, and, consequently, only wrought or malleable iron.
Steel has been produced as a carburet by simply decarbonizing cast iron in various ways for a long time. The process of refining pig metal formerly in general use, to prepare it for the puddling-furnace by blowing air into the liquid metal in the "finery furnace," partially effects the decarbonization of pig metal and forms steel if continued. But the mechanical arrangement of the finery-furnace, and the action of the air blow ing from the surface downwards, instead of from the bottom upwards, does not admit of economical or uniform results, since the iron becomes oxidized before the whole is sufficiently decarbonized to form steel.
A similar process, however, has been long in operation at the celebrated steel and iron works, called Konigshiitte (king's forge), in Upper Silesia, Germany, where "natu ral steel," or a carburet, is made direct from the cast iron by means of a furnace on the principle of the old refining furnace; but the blast is supplied from below, and the pig metal, when melted, falls down through the blast to the bottom of the hearth in the shape of steel,—a process which may be made equally available with that now so cele brated under the name of the Bessemer process; and, as before stated, the same use is made of air for the decarbonization of cast iron in the puddling process, except that it is blown into the melted liquid in the latter, while the metal falls through the blast in the former.
Cast iron may be thoroughly deoxidized and refined by falling, while in a molten condition, through a strong blast of air and steam, the steam being produced by jets of water, or by the falling of the metal into water. As shown in the Nasmyth invention, described in a former page, steam is more effectual than air in deoxidizing cast iron.