krypton

Krypton is element 36, a noble gas isolated in 1898 by Scottish chemist William Ramsay and English chemist Morris Travers at University College London. They found it by slowly evaporating liquid air, a technique that had already yielded argon and neon earlier that same summer. Krypton was the third noble gas they identified within a single month, a rate of discovery that has never been repeated.

Ramsay named the element from the Greek kryptos, meaning hidden, because it had concealed itself so thoroughly in the atmosphere despite being present in every breath ever taken. The same root gives English cryptic, encrypt, and crypt: the hidden vault beneath a church floor. Ramsay drew on Greek for all his noble gas names: neon from neos (new), xenon from xenos (strange), argon from argos (idle).

Krypton exists in Earth's atmosphere at about 1.14 parts per million: present everywhere, detectable only by careful measurement, practically invisible in ordinary life. Between 1960 and 1983, the International Bureau of Weights and Measures used a specific wavelength of krypton-86 radiation to define the meter: one meter was exactly 1,650,763.73 wavelengths of that orange-red light. The hidden element was, for twenty-three years, the hidden standard of all physical measurement.

The name achieved its most famous afterlife in 1938 when Jerry Siegel and Joe Shuster introduced Superman to readers of Action Comics. They named his home planet Krypton, borrowing the element's connotation of something rare, hidden, and powerful. The fictional planet became better known than the real element for most of the twentieth century, until krypton fluoride lasers found industrial applications in semiconductor manufacturing and eye surgery.