. A treatise on steel : comprising its theory, metallurgy, properties, practical working, and use. d 300 kilog. of charcoalare required. It follows that the ore, which is gene-rally very rich, and contains 55 to 60 per cent, ofpure iron, produces no more than 33 per cent. II. Steel from Raw Iron or Raw Steel. 244. The pig metal used in the Department ofIsere, and in the Alps, for the manufacture of steelfrom raw iron, sometimes called raw steel, is obtained STEEL FROM RAW IRON OR RAW STEEL. 149 from spathic ores with charcoal. It is white; itsgrains are crystallized, quite large, and divergent
. A treatise on steel : comprising its theory, metallurgy, properties, practical working, and use. d 300 kilog. of charcoalare required. It follows that the ore, which is gene-rally very rich, and contains 55 to 60 per cent, ofpure iron, produces no more than 33 per cent. II. Steel from Raw Iron or Raw Steel. 244. The pig metal used in the Department ofIsere, and in the Alps, for the manufacture of steelfrom raw iron, sometimes called raw steel, is obtained STEEL FROM RAW IRON OR RAW STEEL. 149 from spathic ores with charcoal. It is white; itsgrains are crystallized, quite large, and divergent,like those of fine metal. However, it is not muchdecarburized, because a drop of nitric acid put onit will produce a dark spot. 245. The fires employed for converting pig ironinto steel, are a great deal larger than those in usefor refining; they require only 6800 cubic decimetresof air, while over 10,000 are required for cause of such a difference is, that in the work-ing for iron, about one-third of the blast is employedfor decarburizing the pig metal entirely; while in Fig. the conversion of pig metal into steel, only a small quantity of carbon is to be consumed. This ex- 18* 150 TREATISE ON STEEL. plains also why the tuyere is horizontal, instead ofdipping the same as in an iron finery. 246. The size of a raw-steel finery fire in the Isere,is one metre square and metre deep. A sand-stone is used for the bottom, and the sides are builtwith fire-bricks. 247. This mode of working requires four men;one head forgeman and three assistants. 248. The hearth is filled with fine charcoal, whichis beaten down for two or three hours. This iscalled making the brasque. In the middle of thiscarbonaceous mass a hole is dug, to metrein diameter, and metre in depth. This havingbeen done, the hearth is filled with burning coals,covered with breeze (fine charcoal), and the blastbegins to play. This preliminary heating is madeuse of for reheating there some
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