PATENT FORGES AND FURNACES.
A great many patents have been granted in this country and Europe for the produc tion of wrought or bar iron. direct from the ore, but none of them have obtained popu larity. The principle on which all these patent modes are based is the deoxidization of the ores by the waste heat from the hearth where the ores are reduced.
The Harvey patent in this country is as near perfection as any other with which we are familiar, and differs from the improved forge and bloomery, illustrated in figure 178, chiefly in having a puddling hearth in place of a Catalan hearth, in which to convert the ores to metal by the puddling process.
Good iron can be produced at reasonable expense in this furnace, but rich ores are required, and the quantity of fuel and labor is greater in proportion to the iron pro duced in General Harvey's furnace than in the blast-furnace, and the subsequent elabo ration of the pig in the puddling and rolling processes.
If the same ores are used in the blast-furnace, of course the yield will be in propor tion to the richness. The only real advantage we can discern in the Harvey patent is in the application of the fuel. Using rich ores, good iron can be produced with almost any kind of fuel capable of producing a strong heat,—for instance, pine-knots, charcoal, coke, bituminous coal, or anthracite, and perhaps hard, dry woods. But in the blast
furnace superior iron can be produced only with pure fuel, and the best only with char coal. In this respect, the improved forge and bloomery, illustrated in figure 178, has perhaps less merits than the Harvey furnace; but the rapidity and simplicity of the operation in the former entitle it to equal consideration. In regard to economy, how ever, neither can compete with the modes now generally in use; that is, by means of the blast-furnace and subsequent puddling process, with rolling-mills for the elaboration of the has from the pig.
As before observed, these furnaces. can only be used economically under peculiar circumstances for the production of superior iron when charcoal cannot be obtained for the purpose. Yet we think it possible that the principle involved is susceptible of great improvement, and that a more economical mode may be developed by mechanical ingenuity, and the wonderful effects of the application of fuel by the Siemen's process —a comparatively recent invention—seem to point out the means; but, as neither space nor inclination will permit us to indulge in theories, we must leave this matter to the development of time.