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To Convert Iron into Steel

This is usually done by the process of cementation, producing what is termed blistered steel. At the bottom of a trough about2 feet square and 14 feet long, usually formed of fire clay, is placed a layer, about 2 inches thick, of a cement composed of 10 parts charcoal and 1 part ashes and common salt; upon this is laid a tier of thin iron bars about 1 inch apart; between and over them, a layer of cement is spread, then a second row of bars, and so on, alternately, until the trough is nearly full; lastly a layer of cement covered with moist sand and a close cover of fire-tiles, so as to exclude the air. The trough is exposed to the heat of a coal fire, until a full red heat, about 2000° Fahr., is obtained and kept up steadily for about 7 days. Д hole is left in the end of the trough, to allow of a bar being drawn out for examination. When a bar, on being withdrawn and broken, has acquired a crystalline texture, the metal is allowed to cool down gradually, some days being allowed for this, and the charge, when cool, withdrawn from the trough. The bars will be found covered with large blisters, hence the name of the process, and increased about 130 in weight. The steel is now sufficiently good for files and coarser tools, but for finer instruments, several varieties of finer steel are required. (Makins).