The finest and very best steel for most purposes, is that which has undergone the process of fusion and a subsequent hammering, called cast steel. It is about ninety years since this steel was introduced by one Huntsman, of Attercliffe, near Sheffield, whose name it continued to bear for a long time; but his rivals at Rotherham and Sheffield, who subsequently undertook the manufacture, gave it the more significant name which it now bears. The process of preparing it on the large scale, is as follows: - Blistered steel is broken into small pieces, and put without any admixture into crucibles that hold about 40 lbs. each, and are covered with a lid. The crucibles are separately deposited in a row of small melting furnaces, which are usually square pots, about 15 inches wide and 3 feet deep, with a grating at bottom; the tops of these furnaces are open, and level with the floor of the foundry; and just below their tops are lateral apertures or flues, leading into the common chimney of all the furnaces; access to the fire-places and ash-pits is had in a vault underneath.

The fuel employed is hard coke, in which the crucibles are entirely imbedded and covered over; then each of the furnace mouths is stopped with a trap-door of fire-bricks, inclosed in an iron frame.

This being done, a very sharp draught of air is produced from the ash-pits, through the fuel, into the lateral flues, and a very intense heat is produced, which, being kept up for four or five hours, the steel is thereby brought into perfect fusion, when it becomes necessary to remove the crucibles, and pour out their contents into cast-iron ingot moulds, prepared for their reception, which are either in the form of a short thick bar, for being tilted, or a thick flat cake, to be lamellated between the rolls. The melter has likewise to prepare himself against the terrible ordeal of the operation just mentioned: to protect himself from the fierce fire of the furnaces, as he bends over their mouths, which would otherwise set his clothes on fire, he puts on an armour of coarse sacking; and then, with a pair of long iron tongs, he gripes the blazing crucible, and, quickly lifting it out of its chamber, pours the contents into the moulds. The subsequent processes upon the ingots, bars, or plates of steel, cast in the moulds to bring them to the required shapes, are in every respect the same as we have described for preparing iron into similar forms; but on account of the greater value of steel, and the delicate manner in which it is often wrought, the rolling and hammering processes become more essential in perfecting the quality, and therefore they are more carefully performed.

For the best purposes, steel is always preferred that has been drawn to its required sizes under a tilt hammer, which gives three or four hundred blows per minute. It is however deserving of remark, that when steel rods and bars have been repeatedly rolled at a low heat, they acquire the same density, and more uniformity, than tilted steel.

Ncedham'8 Patent. - A patent for a new process of casting steel was taken out in 1824, by Mr. Needham, of Davis-street, Fitzroy-square. His plan is to employ large fixed or stationary crucibles (made of fire-stone, or Stourbridge clay), and allowing the steel, when melted, to flow from them, through suitable apertures made in the sides, into the moulds, instead of moving the melting-pots already described. The size and shape of these stationary crucibles, it is stated in the specification, may be varied according to circumstances, but a preference is given to an oblong form, with movable covers, fixed upon bearers of fire-brick or stone, on a plane a little inclined from the horizontal line; at the bottom of each crucible a perforation is made, to which is fixed a tube, that passes through the furnace to the moulds, with a plug at the external end; this being withdrawn, the fluid metal readily discharges itself into the moulds. In this manner several melting-pots may be fixed in one furnace, so that a quantity may be fused sufficient for articles of great magnitude; and as the different descriptions of steel require different degrees of heat for their fusion, the patentee recommends that those which require the least be placed in crucibles above those which require the most; by which arrangement, in casting large shafts or cylinders of steel, those parts that require it may be formed with the best steel, while those parts wherein an inferior steel answers the purpose, may, in like manner, be supplied with it.

If it be required to cast a large cylindrical steel roller, the exterior may be made of a superior quality of steel, and the interior of a common quality, by placing a cylinder of wrought iron within the hollow cylindrical mould; and then directing jets of fluid steel, of distinct qualities, to flow into the opposite sides of this circular wrought-iron partition; the steel will then adhere to the iron, and form one solid roller, of inferior cost, but equal in quality to one made entirely of superior steel.