Initial experiments on silver refining: how did a cupellation furnace work in the 16th century?

Abstract

Cupellation was for long the only known method to retrieve silver from argentiferous lead. The operation took place in a cupellation furnace, a structure made of a wall supporting a sole (the base for the hearth) and topped with a dome. The hearth, where the alloy was placed, was made from clay and ash. There is very little archaeological evidence of this operation. However, since the 16th century, silver refining has been well documented in detailed and illustrated metallurgical treatises, such as Book X in Georgius Agricola’s De re metallica (1556). Conducting experimentations is therefore necessary to understand the technological choices of ancient metallurgists. Eight operations have been carried out over the past two years. They are entirely based on Agricola’s record. The whole process is taken into account in this study: temperature and atmosphere conditions, hearth composition, drawing out of molten litharge and structure of litharge cakes.