The dross, mentioned in Isaiah 1:22, signifies falsity.

(Referencias: Apocalypse Explained 887)

6436. 'They will be on the head of Joseph' means those things with respect to the interiors. This is clear from the meaning of 'the head' as the interiors, for it is there that everything in the human being exists first and foremost. A further reason why the interiors are what are meant by 'the head' lies in correspondence. From correspondence 'the neck' means what is intermediate, 'the body' the exteriors, and 'the feet and soles of the feet' the most external parts. This correspondence has its origin in heaven's presentation of itself as the Grand Man. The inmost heaven where the Lord's celestial kingdom is situated presents itself as the head there; the middle or second heaven where His spiritual kingdom is located presents itself as the body; and the lowest or first heaven as the feet, see 4938, 4939, 5318, 6291.