CUPEL (Lat. cupella, a little tub or vessel), a small earthen cup-shaped vessel used in the refining of metals. It is usually made of phosphate of lime, or the residue of burnt bones, rammed into a mould. In the process of assaying the precious metals, the silver or gold is fused upon a cupel with lead, when the lead becomes oxidated and vitrified, and is absorbed by the substance of the cupel, while the silver or gold remains in a state of purity. This process is called cupellation. See ASSAYING, vol. iii., p. 770.