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manner of the southern barbarians) for the porous metal mass, left after the extraction of the lead, and the year 1590 gives some reasonable ground for this belief.
We will now proceed to the description of the desilvering process.
1st.—The silver containing raw metal (blister-copper, etc.) is mixed with variable quantities of lead (according to the amount of silver) and the whole smelted with a charcoal-fire in a small furnace of fire-proof clay. The fluid metal is then cast in round or square plates, and leaves the name of awase-buki-do.
2nd.—This alloy (awasi-buki-do) is now placed on the inclined bottom of a small liquation furnace and the whole heated gradually. The bad metal with the dissolved silver flows off from the bottom in a liquid state, de namari, whilst the copper and other less fusible metals remain in a solid condition on the hearth. Thus the lead and silver are separated from the copper and other metals. The porous masses which remain on the bottom, are afterwards smelted and purified, to obtain dry copper from them.
3rd.—The cupellation or separation of lead and silver is effected in a low furnace, with a loose covering: on account of its form, this furnace is called a “toad furnace.” The bottom of this furnace consists of a fire-proof plane, covered with a high layer of sifted wood-ashes.
The family Sumitomo exists still in Osaka. At the house of the present head of the family, in Osaka, Nagahori ichome, may be seen several old documents in relation to this fact, and also a collection of old presents, given by the former Dutch Embassies to Sumitomo when they paid the customary visit to his copperworks.
Previously washed with water to extract the soluble matter, this ash floor is stamped and levelled with great care. In the middle a small round cavity is made, to receive the smelted metal. This ash floor is carefully dried and heated in order that there may be no chinks by which the silver might be lost. The alloy of lead and silver is then placed on the bottom, the furnace is closed with a low covering of fine clay and the whole strongly
