n. [ LL. cupella cup (cf. L. cupella, small cask, dim. of cupa) : cf. F. coupelle. See Cup, and cf. Coblet. ] A shallow porous cup, used in refining precious metals, commonly made of bone ashes (phosphate of lime). [ Written also coppel. ] [ 1913 Webster ]

Cupel dust, powder used in purifying metals. [ 1913 Webster ]

v. t. [ imp. & p. p. Cupelled p. pr. & vb. n. Cupelling. ] To refine by means of a cupel. [ 1913 Webster ]

pos>n. [ See Cupel. ] The act or process of refining gold or silver, etc., in a cupel. [ 1913 Webster ]

☞ The process consist in exposing the cupel containing the metal to be assayed or refined to a hot blast, by which the lead, copper, tin, etc., are oxidized, dissolved, and carried down into the porous cupel, leaving the unoxidizable precious metal. If lead is not already present in the alloy it must be added before cupellation. [ 1913 Webster ]