Johann Schröder
Encyclopedia
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
was an element. In 1649, he produced the elemental form of arsenic by heating its oxide, and published two methods for its preparation.