Ethiops
Pronunciation : E"thi*ops n.
Etymology : [NL. See Ethiop.] (Old Chem.)
Definition : Defn: A black substance; -- formerly applied to various preparations of a black or very dark color. [Written also ?thiops.] [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.
Source : Webster's Unabridged Dictionary, 1913