Colorless gas with a very slight odor. Slightly anesthetic when inhaled m.p. -111.9 ºC; -169.4 ºF b.p. -107.1±3 ºC; -160.8±5.5 ºF density (gas) 0.005887±0.000009, (liquid) 3.52 (-109 ºC) g/cc; (gas) 0.36751±0.00056, (liquid) 219.75 (-164 ºF) pound/cubic foot	memory peg
	1898 Sir William Ramsay and Morris W. Travers, England
	ξενος (xenos) = strange (Greek)

Xenon occurs in slight traces in gases within the Earth and is present to an extent of about 0.0000086 percent, or about one part in 10,000,000, by volume of dry air.

Xenon was the last noble gas to be discovered. In the sequence of several studies made by Sir William Ramsay (1852-1916) and Morris W. Travers (1872-1961), in 1898, and by repeated fractionation of Krypton an extremely dense gas was obtained that those two scientists were unable to identify (12 July 1898). The spectroscopic analysis of that gas revealed that was a new element that was named Xenon. This name derives from the Greek word ξενος [xenos] = strange.

Xenon is used in lamps that produce intense, extremely short flashes of light, such as stroboscopes and lights for high-speed photography. When a charge of electricity is passed through the gas at low pressure, it emits a flash of bluish-white light; at higher pressures white light resembling daylight is emitted. Xenon flash lamps are used to activate ruby lasers.

Further reading:

• W. Ramsay, The Gases of the Atmosphere: The History of Their Discovery. London: Macmillan, 1915.
• Mary Elvira Weeks, Discovery of the Elements, comp. rev. by Heny M. Leicester (Easton, Pa.: Journal of Chemical Education, 1968), pp. 767-769.
• Edelgasse. Gmelins Handbuch der anorganische Chemie, 8. Aufl.; System-Nummer 1 (1926).