dephlogisticated air

Meanings

1. oxygen gas, as originally thought to be air deprived of phlogiston (“the hypothetical fiery principle formerly assumed to be a necessary constituent of combustible bodies and to be given up by them in burning”).

Etymology

From dephlogisticated (“from which the phlogiston has been removed”) + air, coined by the English chemist Joseph Priestley (1733–1804) in a 1775 article entitled “An Account of Further Discoveries in Air” published in the Philosophical Transactions of the Royal Society: see the quotation.