[SunkenCiv]

Alchemy or al-chema means, "the black", as in the black arts.

[Antoninus]

Alchemy or al-chema means, "the black", as in the black arts.

I have seen numerous derivations of the word, that being one of them. However, in Partington's A Shorth History of Chemistry, which is cited in the original post, he specifically says that chemeia, "is not a Greek word, and appears to have been derived from the native designation of Egypt, a country which Plutarch, in his treatise on Isis and Osiris, written about 100 AD, says was called chemia on account of the black color of its soil. This statement is confirmed by the Egyptian inscriptions, where the hieroglyphic form of the word is used. The name probably meant, "the Egyptian art", and never had the meaning of "black art" as applied to magic."

Not saying this is right, but it's an alternative viewpoint.