from
The Collaborative International Dictionary of English v.0.48
Slag \Slag\ (sl[a^]g), 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.
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2. The scoria of a volcano.
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3. (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.
[Webster 1913 Suppl.]
{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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