Ba=BARIUM
Barium is a very reactive, silvery metal, which quickly oxidizes in air and easily starts to burn. Therefore elementary barium is hardly used except as a getter material, which binds unwanted rest gases in vacuum tubes. Barium compounds are scarcely used, too, water soluble compounds of it are toxic. The non-water-soluble barium sulfate, known as barium meal, is used as a radiographic contrast medium.
