Arsenic and its compounds are poisonous. These values, however, are being studied, and may be lowered. Arsenic is also used in bronzing, pyrotechny, and for hardening and improving the sphericity of shot. Arsenic is available in high-purity form. It is finding increasing uses as a doping agent in solid-state devices such as transistors.
Gallium arsenide is used as a laser material to convert electricity directly into coherent light.
Twenty-five other radioactive isotopes and isomers are known. Used as a catalyst in the manufacture of ethylene oxide. Used in semiconductor devices. A yellow modification which has no metallic properties is obtained by sudden cooling of arsenic-vapor. This yellow arsenic is converted back to the gray modification upon very short exposure to ultraviolet light.