FLUX, in Metallurgy, is sometimes used synonymously with fusion. For instance, an ore, or other matter, is said to be a liquid flux, when it is completely fused.
But the word flux is generally used to signify certain saline matters, which facilitate the fusion of ores, and other matters which are difficultly fusible in assays and reductions of ores; such are alkalies, nitre, borax, tartar, and common salt. But the word flux is more particularly applied to mixtures of different proportions of only nitre and tartar; and these fluxes are called by particular names, according to the proportions of these ingredients, as in the following article.