'Scum' in the Bible

Wherefore thus saith the Lord GOD; Woe to the bloody city, to the pot whose scum is therein, and whose scum is not gone out of it! bring it out piece by piece; let no lot fall upon it.

Then set it empty upon the coals thereof, that the brass of it may be hot, and may burn, and that the filthiness of it may be molten in it, that the scum of it may be consumed.

She hath wearied herself with lies, and her great scum went not forth out of her: her scum shall be in the fire.