What does "ethiops" mean?

Ethiops: A black substance; -- formerly applied to various preparations of a black or very dark color. [Written also Æthiops.] [Obs.] Ethiops martial (Old Chem.), black oxide of iron. -- Ethiops mineral (Old Chem.), black sulphide of mercury, obtained by triturating mercury with sulphur. -- Ethiops per se (Old Chem.), mercury in finely divided state, having the appearance of a dark powder, obtained by shaking it up or by exposure to the air.