White Arsenic: Orpiment Roasted in Air, the Fume Condensed

White arsenic (arsenic trioxide) is made by roasting arsenic minerals in air: roasting orpiment, an arsenic sulfide ore, drives it off as a fume that condenses as a white solid. It is a deadly poison, and the roast also gives off sulfur dioxide. It is the arsenic source for Scheele's green and Paris green. The picture: our diagram of kiln and condensing chamber.