Slag word meaning and definition

[noun] the scum formed by oxidation at the surface of molten metals

\Slag\, n. (Metal.) A product of smelting, containing, mostly as silicates, the substances not sought to be produced as matte or metal, and having a lower specific gravity than the latter; -- called also, esp. in iron smelting, {cinder}. The slag of iron blast furnaces is essentially silicate of calcium, magnesium, and aluminium; that of lead and copper smelting furnaces contains iron.
\Slag\, v. i. & t. [imp. & p. p. {Slagged}; p. pr. & vb. n. {Slagging}.] (Metal.) To form, or form into, a slag; to agglomerate when heated below the fusion point.
\Slag\, n. [Sw. slagg, or LG. slacke, whence G. schlacke; originally, perhaps, the splinters struck off from the metal by hammering. See {Slay}, v. t.] 1. The dross, or recrement, of a metal; also, vitrified cinders. 2. The scoria of a volcano. {Slag furnace}, or {Slag hearth} (Metal.), a furnace, or hearth, for extracting lead from slags or poor ore. {Slag wool}, mineral wool. See under {Mineral}.

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