The Collaborative International Dictionary of English v.0.48:

Pyrothonide \Py*roth"o*nide\, n. [Pyro- + Gr. ? linen.] (Med.)
   A kind of empyreumatic oil produced by the combustion of
   textures of hemp, linen, or cotton in a copper vessel, --
   formerly used as a remedial agent. --Dunglison.
   [1913 Webster]