Word: krypton
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Dates: during 1960-1969
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...effect tossed on the scrap heap. A General Conference on Weights and Measures, meeting at Paris, made a wave length of light the new official standard of length. The meter is now denned as 1,650,763.73 wave lengths of the orange-red light given off by electrically excited krypton 86, a rare gas extracted from the atmosphere. The U.S. inch is 41.929.399 wave lengths...