Metals and metal-working in old Japan . own in fig. 8. It consists simply of a hemispherical cavityin the floor of the melting-room, lined wdth refractory was filled wath ignited charcoal, upon which the cakesof silver were placed and covered with more charcoal. Thebellows were started, and when the silver w^as completelymelted, and the necessary amount of copper had been added. ( 41 )the fire was raked off, the molten metal stirred well with a stickof pinewood, and laded with an iron ladle usually into canvasmoulds set in water. It was never cast in ornamental forms,but always in sm
Metals and metal-working in old Japan . own in fig. 8. It consists simply of a hemispherical cavityin the floor of the melting-room, lined wdth refractory was filled wath ignited charcoal, upon which the cakesof silver were placed and covered with more charcoal. Thebellows were started, and when the silver w^as completelymelted, and the necessary amount of copper had been added. ( 41 )the fire was raked off, the molten metal stirred well with a stickof pinewood, and laded with an iron ladle usually into canvasmoulds set in water. It was never cast in ornamental forms,but always in small cakes or bars, which were fashioned solelywith the hammer and chisel. When bars of debased silver— silver containing largequantities of copper—were cast (a practice which unfortunatelywas not seldom followed in the old Mints, when the militaryrulers of the country were in need of money) a special modeof procedure was adopted. The silver was always poured intomoulds which were set in trouglis of hot water as shown in fig. 8;. Fig. 8.—Furnace and Moulds used in Melting and Casting Silver. the reason for this being that the alloy contained so muchcopper that if cast in the ordinary way the bars would becoated with a black layer of copper oxide, which was difficultto remove. By placing the moulds under water this oxidationwas prevented, and castings with a clean metallic surfacewere obtained. The castings were, however, of a coppery hue, and thisrequired removal. They were therefore heated to redness andthen plunged into plum vinegar containing common salt in ( 42 ) solution. After digestion in this for some hours, they wereboiled in plum vinegar without salt, and were then washedwith water and dried. By these operations the copper in thealloy was removed from the surface layers, and a coating ofpure silver left. The castings sometimes contained only from15 to 20 per cent, silver, yet when the above operations hadbeen carefully carried out these low alloys have the ap
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Keywords: ., boo, bookcentury1900, bookpublisherlondonsn, booksubjectmetalwork
