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tion, the temperature is again raised to ensure the complete separation of the copper from the slag. The metal is finally cooled with a little water and taken out of the cavity in the form of sheaves. It bears the name Ara-do=crude copper (Engl. blistered copper: Germ. schwarz-kupfer) and is now carried from the melting place into the refinery.
4th.——Refining to obtain dry copper (Gaar-kupfer) (Mabuki-do).
The two following operations were formerly practised at the Government Refinery at Osaka only; but are now common in all the provinces.
The blistered copper obtained by the foregoing process, still contains some quantity of iron, sulphur and a small proportion of tin, lead, arsenic, &c. To remove all these impurities about 150 kilogrammes of the metal are placed in cavities of fire-proof clay made in the hearth of a small furnace similar to that already described, the whole is covered with charcoal and air is allowed to pass over the surface of the melted copper. By these means small quantities of iron, tin, and also of copper are oxidized, and form with the silicic acid of the hearth or ashes a slag which floats upon the surface of the melted copper. At the same time any remaining traces of sulphur are removed as suphurous acid. The slag is constantly removed with long iron ladles until the surface of the metal remains pure. Finally, a little water is thrown upon it to produce the solidity of the upper portion, so that a sheave of copper may be taken out of the cavity. This is repeated until the crucible is empty. The cakes of dry copper thus obtained still contain an excess of cuprous oxide which is removed in the following manner. In the stage last described it is called by the Japanese Ma-buki-do=“often melted copper” (Gaar-kupfer).
5th.—Casting the bar copper, (Tough copper) (Saö-bu-kido).
In order to obtain the fine Japanese bar copper, which has a just reputation for its purity, the dry copper of the former process is smelted in quantities of from 30
