Flux, << fluhks, >> in chemistry and metallurgy, is a substance that lowers the melting point of a substance to which it is added. A flux added to ore before melting helps to separate the impurities from the metal. In smelting iron, the flux used is generally limestone. This combines readily with the impurities to form slag, which can then be easily removed. Fluxes made of borax, soda, and potash are used to separate base metal from gold and silver. The term flux also refers to the rate of flow of matter or energy across a given surface.
