Ethiops per se

from The Collaborative International Dictionary of English v.0.48

Ethiops \E"thi*ops\n. [NL. See {Ethiop}.] (Old Chem.)
   A black substance; -- formerly applied to various
   preparations of a black or very dark color. [Written also
   {[ae]thiops}.] [Obs.]
   [1913 Webster]

   {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. Ethmoid