The slag or dross that remains after the smelting of metal from an ore.
Rough masses of rock formed by solidified lava, and which can be found around a volcano's crater.
The scoria on the surface of molten metal in the ladle.
Silt or sediment deposited from flowing water.
That which sullies or defiles.
The liquid discharges from kitchens, washbasins, toilets etc; sewage.