25 II. "When Morn, escorted by the dancing Hours, O'er the bright plains her dewy lustre showers; Till from her sable chariot Eve serene Drops the dark curtain o'er the brilliant scene; You form with chemic hands the airy surge, 30 Mix with broad vans, with shadowy tridents urge. SYLPHS! from each sun-bright leaf, that twinkling shakes O'er Earth's green lap, or shoots amid her lakes, Your playful bands with simpering lips invite, And wed the enamour'd OXYGENE to LIGHT.-- 35 Round their white necks with fingers interwove, Cling the fond Pair with unabating love; Hand link'd in hand on buoyant step they rise, And soar and glisten in unclouded skies. Whence in bright floods the VITAL AIR expands, 40 And with concentric spheres involves the lands; Pervades the swarming seas, and heaving earths, Where teeming Nature broods her myriad births; Fills the fine lungs of all that _breathe_ or _bud_, Warms the new heart, and dyes the gushing blood; 45 With Life's first spark inspires the organic frame, And, as it wastes, renews the subtile flame. [_The enamour'd oxygene_. l. 34. The common air of the atmosphere appears by the analysis of Dr. Priestley and other philosophers to consist of about three parts of an elastic fluid unfit for respiration or combustion, called azote by the French school, and about one fourth of pure vital air fit for the support of animal life and of combustion, called oxygene. The principal source of the azote is probably from the decomposition of all vegetable and animal matters by putrefaction and combustion; the principal source of vital air or oxygene is perhaps from the decomposition of water in the organs of vegetables by means of the sun's light. The difficulty of injecting vegetable vessels seems to shew that their perspirative pores are much less than those of animals, and that the water which constitutes their perspiration is so divided at the time of its exclusion that by means of the sun's light it becomes decomposed, the inflammable air or hydrogene, which is one of its constituent parts, being retained to form the oil, resin, wax, honey, &c. of the vegetable economy; and the other part, which united with light or heat becomes vital air or oxygene gas, rises into the atmosphere and replenishes it with the food of life. Dr. Priestley has evinced by very ingenious experiments that the blood gives out phlogiston, and receives vital air, or oxygene-gas by the lungs. And Dr. Crawford has shewn that the blood acquires heat from this vital air in respiration. There is however still a something more subtil than heat, which must be obtained in respiration from the vital air, a something which life can not exist a few minutes without, which seems necessary to the vegetable as well as to the animal world, and which as no organized vessels can confine it, requires perpetually to be renewed. See note on Canto I. l. 401.]