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buki-do.) Lately the art of refining has been better understood in the provinces where the ore has been dug and smelted. This industry still flourishes especially in the districts round Osaka.
The extraction of the metal from the ore in Japan rests principally on the same basis as our Western continental copper smelting. The melting process according to Japanese methods is divided into several sections.
1.—Calcining or roasting the ore to expel part of the sulphur, arsenic, water &c. and powdering in order to obtain the black powder Kudzu.
2nd.—Fusion with silicate to remove the oxide of iron formed by the roasting process, to convert at the same time the oxide of copper, formed by the roasting, into copper sulphide, and to obtain finally a coarse metal (spur stein) Jap. Kawa-do=Sheave copper.
3rd.—Calcination of the coarse metal: a. to convert the still remaining parts of sulphide of iron into oxide of iron: b. fusion with some of the clay of the covering to remove the whole of the iron in the slag: and c. boiling the metal to expel the sulphur as sulphurous acid. Ara-do=Crude copper.
4th.—Refining, to remove the cuprous oxide and bring the copper to tough-pitch. Tough copper, bar copper, Sao-buki-do=Copper melted bar.
1st.—Roasting the ore.
The coarsely powdered ore is calcined in a broad loamy furnace of about 25 metr. in length and 12 metr. in breadth. The furnace is covered with a shed, and, near to the bottom of it, has many openings for the entrance of the air. On the bottom of this furnace a layer of dry wood is placed, then a layer of ore, and thus alternately wood and ore till there are five double layers. Fire is then placed below, and the whole left for a period of 20-25 days. Part of the sulphide of iron is converted into sulphate of iron, by absorbing oxygen at the beginning of the roasting, and this sulphate is afterwards decomposed by a higher temperature, evolving sulphurous acid and leaving oxide of iron. A very small portion of the sulphide of
