Discovery of krypton

Krypton was discovered in 1898 by the British chemists William Ramsay and Morris Travers at University College London. Working in the weeks after they had found neon, they allowed a sample of liquefied air to evaporate almost completely and examined the least volatile residue with a spectroscope. They saw bright lines that did not match any known element and named the gas krypton, from the Greek kryptos, meaning hidden. It is a colourless, rare noble gas that makes up about one part per million of the atmosphere, and it was followed within weeks by the discovery of xenon. Krypton is used in some lights and lasers. From 1960 to 1983 the international standard for the metre was defined by the wavelength of light emitted by one of its isotopes, krypton-86.

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