Chlorine, element number 17, was first isolated by German-Swedish chemist Carl Wilhelm Scheele in 1774, and he is generally credited with its discovery. Scheele, however, did not recognize chlorine as an element, mistaking it for a compound, an oxide from the hydrochloric acid he used as a source. British chemist Humphry Davy repeated Scheele’s experiment in 1810 and determined that it was indeed an element. Davy named it chlorine because of the yellow-greenish color of the gas, from the Greek χλωρός (chloros, green) + –ινη (–ine). Davy wrote in the Philosophical Transactions of the Royal Society in that year:

It has been judged most proper [...] to call it Chlorine, or Chloric gas.1

The chemical symbol for chlorine is Cl, taken from two of the first letters of its name.

1Oxford English Dictionary, chlorine, 2nd Edition, 1989, Oxford University Press, accessed 1 September 2009,

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