The preceding articles are descriptive of three distinct modes of preparing steel. First, by the careful refinement of cast-iron; second, by the stratification of malleable iron with charcoal; and third, by the application of gaseous carbon to the metal. A fourth process, materially differing from those, but producing very similar results, and attended with some peculiar advantages, was patented in the year 1800 by Mr. Mushat, the gentleman whose metallurgical labours we have before noticed. The specification of the patent directs that malleable iron (in scraps or bars) is to be put into a crucible, together with a due proportion of powdered charcoal, or pit coal, plumbago, or any other substance containing the carbonaceous principle, and subjected to an intense heat in an air or blast furnace until the metal is reduced to a fluid state, when it is to be poured out into moulds to form ingots, or any other article that may be required; which castings will be of a similar nature to the steel produced by cementation.

But in those cases when iron ore can be obtained sufficiently rich and free from foreign admixtures, the patentee proposes to save all the time and expense attending the tedious operations necessary for the conversion of such ore, first into cast-iron, and afterwards into bar iron; for such ore, he observes, being previously roasted or torrified, may be substituted for the malleable iron, and the result will be cast-steel, provided the proper quantity of carbonaceous matter be used, as for the common and ordinary qualities of cast steel. The quantity of carbonaceous matter required, is much less than had been previously supposed to be necessary. In employing wood charcoal, from a seventieth to a ninetieth of the weight of the iron being sufficient; and when the quantity is increased beyond a seventieth to a sixtieth, or a fortieth of the weight of the iron, the steel becomes so fusible that it may be run into moulds of any shape, and afterwards be capable of being filed and polished. Hence, by casting, may be constructed stoves, grates, kitchen utensils, wheels, mill-work, and a great variety of things which could not be so made by the processes previously in use.

By varying the proportions of the carbonaceous matter, he can make as great a variety in the qualities of the steel, as the various kinds of pig-metal differ from each other. Cast-steel, made in the ordinary way, Mr. Mushat observes, is so volatile when in fusion as not to admit of being run into any shape except straight moulds of considerable diameter; but that steel of such density as to admit of being cast into any form may be produced by his process, by increasing the quantity of charcoal, and fusing the matter as before directed. To produce qualities of steel softer than is usually manufactured by the common processes, he uses a very small proportion of charcoal, sometimes so little as a two-hundredth part of the weight of the iron; and he states that steel produced with any proportion of charcoal not exceeding the one-hundredth part, will generally be found to possess every property requisite to its being cast into those shapes which require great elasticity, strength, and solidity; and will also be generally found capable of sustaining a white heat, and of being welded together like malleable iron.