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to 35 kilos in loose crucibles of fire-proof clay. The copper is covered with powder of pure charcoal in order to reduce the small quantity of sub-oxide of copper contained in the dry copper. This portion of sub-oxide makes the copper brittle and must therefore be partly at least removed if copper of great tenacity is required. The whole of the cuprous oxide is not to be removed because copper which is perfectly free from the sub-oxide does not possess the maximum of toughness, a fact which the copper smelters in England fully recognize, taking the greatest care to avoid ‘underpoled’ as well as ‘overpoled’ copper. When the metal is liquefied and all the impurities lave been carefully removed from the surface, it is cast in iron moulds which are divided in 10-12 bar-forms, or sometimes also into square cakes. These moulds are placed in warm water and are then filled with liquid metal. As soon as the bars or plates are solidified, they are taken out of the moulds with a pair of pincers and immediately put for a short time into the vapour of boiling-water. By this means—which is not resorted to in Europe[1]—the copper bars or plates assume the beautiful high red colour characteristic of Japanese bar copper. It now bears the name of Saö-buki-do, i.e. copper melted in bars. If the roasting has not been sufficient, there remain some traces of arsenic in the bar copper which make it brittle and greatly depreciate its commercial value. If the copper ore—ns is the case with many kinds of copper pyrites and grey copper ore—contains enough gold or silver, the coarse metal obtained from the second operation is worked in another manner in the refineries. We will describe afterwards the process of separation of these precious metals, which consists of a liquidation-process, in the “metallurgy of silver.”
Ranzan states that copper is found and smelted in more than 40 provinces of Japan. Our different Japanese sources and my own observations give the following places as the most interesting [vide Japanese Mineralogy. Seki-
- ↑ In Europe a very small admixture of lead is sometimes used in order to obtain a fine red colour for the bars or plates.
