YELLOW ORPIMENT. 539 Asia.—In Natolia and China. America.—Zitnapan in Mexico-, and the north-west territory of the United States*. Observations. 1. Its foliated fracture distinguishes it from'sulphur. 2. Hausmau, at page 209. of his Mineralogy, describes a third subspecies of orpiment, under the name Slaggy Orpiment, and which he says has a conchoidal fracture, and glistening resinous lustre, and is found at Andreas- herg in the Ilartz. 3. This substance appears to differ from the arsenic of the ancients. It differs from the substance commonly called Arsenic at the present day, in containing a portion of sulphur; and in being consequently of a yellow colour; "'hereas our arsenic is perfectly white. Pliny and Theophrastus describe arsenic as having a yellow colour. Thus l’liny says, that the best arsenic is “ colons in auro excellentis.” Iheophrastus sajs, on account of its resemblance in colour, ochra (Z X! ,x) is used Instead of arsenic; but the term itself is apparently- derived from its yellow colour ; and that it was of this colour, appears further probable, from its being changed to a red by calcination, which is mentioned by lheophras- tus; and being thus converted into the substance called nu.r^ which answers exactly to our r.ed-ochre. Of San- <Iaruca, which is used as a synonym for realgar or red or- pinient, Pliny says, “ mtlior quo mngnis rufescit.” The term afrom which our word Arsenic is derived, "as an epithet applied by the ancients to those natural substances, the properties of which were found to be of a strong, and, as it were, masculine character; and as the poisonous quality of arsenic was soon found to be remark-