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the iron will gradually run in a liquid state to the bottom of the furnace, and is cast in sand-forms by removing the clay stopper of the lowest opening. The cold metal is sometimes purified by a second smelting in another similar, but smaller furnace, and cast in the desired forms.
The process is—as in our blast furnace system—founded on the reduction of the oxidised ore by means of the carbonic oxide, which is formed, when the carbonic acid, proceeding from the burning of the lowest parts of coal, passes over the red-hot fuel above the burning coal. It is this carbonic oxide which reduces the ore to the metallic state when it comes into contact with it at a red heat. The carbonic oxide is converted by this means into carbonic acid, while the iron is left in the metallic state. The iron and the slag both run to the bottom, where the slag forms a layer above the heavier metal. Old iron is worked by the Japanese in the same manner.
In the province of Satsuma, not far from Kagosima, a European blast-furnace has been erected for some years, which produces, together with other Japanese furnaces at that place, considerable quantities of cast-iron.
The conversion of cast-iron into bar or wrought iron consists in removing as far as possible the carbon, silicon, sulphur, phosphorus and other substances from the cast-iron. This purification rests upon the principle, that when cast-iron is strongly heated in contact with air or oxide of iron, its carbon is evolved in the form of carbonic oxide, while the silicon is converted into silicic acid, which unites with another portion of oxide of iron to form a fusible slag. The Japanese follow the same principle, without however knowing the theory of this puddling process; they mix cast-iron with a little quartz or sand and some iron-scales, heat the whole with charcoal in small furnaces of fire-proof clay—similar to the one already described—and keep the metal during several days (our Japanese author says seven days) in a fluid-state, under continuous blowing with the bellows. We have not seen this process ourselves, because as already stated, the manufacture of bar-iron is now almost abandoned in Japan. The puddling of the
