Xenon, chemical element, symbol Xe; for physical constants, see Periodic Table. Xenon was discovered by Sir William Ramsay and Morris W. Travers in 1898. It occurs in the atmosphere to the extent of one part in 20 million. It is obtained from liquid air residues and from the gases evolved from certain mineral springs. Xenon is a colorless, odorless, and chemically inert gas. It is a member of the noble or “inert” gases. The noble gases do not normally combine with other elements, but the existence of many xenon compounds has been established. Xenon difluoride, tetrafluoride, hexafluoride, and others have been prepared. It is used in special electric lamps.