Empyreal air

oxygen gas.

See also: Empyreal

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in periodicals archive ?
Drawing from her celestial song "empyreal air, / Thy temp'ring," he calls upon her to return him safely to his "native element." For Milton the test of her celestial power lies less in flight than in a safe return: "Standing on earth, not wrapt above the pole, / More safe I sing with mortal voice." His fear is that, untempered, her song in him may become "this flying steed unreined" that left Bellerophon dismounted "on th'Aleian field ...