GEORGE BERNARD / SCIENCE PHOTO LIBRARY GEORGE BERNARD / SCIENCE PHOTO LIBRARY
Silver purification. Historical engraving showing workers using various furnaces to separate silver from its ores. The use of heat for the treatment of an ore is known as pyrometallurgy. The equipment used is numbered and includes: 1, an athanor furnace, which is self-feeding and maintains a uniform temperature. Taken from The Laws of Art and Nature, in Knowing, Judging, Assaying, Fining, Refining and Inlarging the Bodies of Confin'd Metals (1683) John Pettus, a translation of the work by Lazarus Erckern.
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