A process in metallurgy, the separation of gold or silver from impurities by melting the impure metal in a cupel (crucible) and then directing a blast of hot air on it in a special furnace. The impurities, including lead, copper, tin, and other unwanted metals, are oxidized and partly vaporized and partly absorbed into the pores of the cupel. It is used to obtain silver by separating it from the lead with which it is naturally associated in argentiferous lead ores, or to obtain gold from the naturally occurring alloy of argentiferous gold (electrum).