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Sponge-metal Process

This process of obtaining steel direct from the ore consists in first producing a sponge of malleable iron in vertical brick retorts charged with alternate layers of charcoal and ore, and fired from the outside. It takes about three days to obtain the metallic sponge, when it may be either melted in crucibles, along with substances rich in carbon, for steel; or it can be at once balled, hammered, cut, piled, reheated, and rolled into merchant-bars. See CRUCIBLE-STEEL.

Spouts for Cupolas.--Spouts, as a rule, are made too small. Given plenty of width, there is room to get at the breast, and added depth lowers the stream--a desideratum when a crooked tap is made. They should always be set so that the bottom will be three inches below the sand-bed of the cupola. A slight incline induces motion of the stream. While it is possible to obtain good work from spouts prepared with sand each heat, preference must be given to those made with an internal flange on the front end corresponding to the shape of the spout when formed; this flange serves to hold securely the fire-bricks with which the inside may be built, thus making an imperishable channel close up to the breast. A slight rub over with fire-clay and a coat of blacking completes the operations at this point. The bricks make a safe abutment for the breast, and when the sand-bottom is made the portion immediately adjacent to the fire-brick bottom of the spout can be made good with daubing mixture stiffened well with the fire-sand. See BREAST-HOLE; SAND-BED; CUPOLA; DAUBING.