FLUX

a substance or mixture added to a furnace charge, to combine with the gangue minerals and form a fusible slag. (Gangue is the name given to the earthy or mineral extraneous matter usually found a ociated with the valuable minerals in ore deposits.) The flux required varies with the nature of the gangue; if this is siliceous, limestone or iron ore is used; but if it is basic, a siliceous flux is added. In the smelting of iron ores, limestone is largely used asa fiux, the slag formed being mainly a silicate of lime and alumina. The fluxes made use of in a ays or chemical experiments consist usually of alkalies and alkaline salts, as borax, cyanide of pota ium, carbonate of sodium, common salt, which render the earthy mixtures fusible by converting them into gla . The fluxes used in pottery are various, but almost all consist of litharge or red-lead, borax, carbonates of pota ium and sodium, and sand. In soldering operations fluxes are used to prevent oxidation and to di olve any oxide which may be formed, the common fluxes being tallow, resin, and zine chloride.