Page:Popular Science Monthly Volume 38.djvu/176

164 added from time to time as the work progressed, and sometimes the mass of fuel and ore was heaped up three or four feet. After an hour and a half or two hours of blowing, most of the iron in the ore was found in a pasty condition at the bottom of the hearth, in a bath of liquid "cinder" formed from the impurities of the ore and the ashes of the fuel; the blast was then augmented and most of the "cinder" drawn off through a "tap-hole" in the front side of the hearth, after which the pasty iron was lifted by bars until it was opposite or somewhat above the tuyère, and was there heated and manipulated until it became a spongy but coherent mass or "ball" of forgeable iron, twelve or fifteen inches in diameter, whose numerous



cavities were filled with a more or less fluid cinder. For the purpose of expelling this "cinder" and imparting greater density and coherence to the iron, the ball was then removed from the fire (Fig. 11) and taken to a "trip-hammer" (Fig. 12) and "shingled."

The resulting "bloom," roughly cylindrical or rectangular in shape, represented about three fourths of the iron contained in the ore used; the remainder went into the cinder and was lost. The weight of the "bloom" obtained at a single operation was usually from three hundred to three hundred and fifty pounds.