Noah Webster
Turpeth
TUR'PETH, noun A root brought from the East Indies, particularly from Cambaya, Surat and Goa, or from Ceylon. It is the cortical part of the root of a species of Convolvulus. That sold in the shops is a longish root, of the thickness of the finger, resinous, heavy, and of a brownish hue without, but whitish within. It is cathartic.
Turbith or turpeth mineral, is the yellow precipitate of mercury, called sometimes yellow subsulphate of mercury, or subdeutosulphate.