Furnaces for cupellation and liquation of metal ores, 1819.
© Science Museum / Science & Society Picture Library
Engraving by Baltard, showing equipment for cupellation (asaying or refining using a refractory material which absorbs impurities) and liquation (melting and purifying). Illustration from 'De la richese minerale: Considerations sur les mines, usines et salines des differens etats, presentees comparativement' by Antoine-Marie Heron de Villefose (1774-1852), published in Paris in 1819. In English, the title is 'Of mineral riches: Considerations on the mines, factories and salt-mines of different countries, presented comparatively'.