[83]Air is not unfit for Respiration, by having lost its vital Principle, but because it has imbibed Floguiston, which cannot easily be separated from it, but by Agitation in Water. Cavallo, on Air, Pages 479, 670.
[84] For if Moisture be one Cause, which keeps the Particles of Air at greater Distances from each other; this Cause decreases at great Altitudes.
If also the Elasticity decreases in Proportion, not only to the Height, but the Driness; its Particles must, on both Accounts, approach each other, at great Altitudes: tho’, from the Altitude only; they woud separate according to the Rule, viz. that the Rarity of the Air is proportionable to the Relaxation of the Force compressing it.
So that at the Height of 8 or 10 Miles, a Quantity of Air taken from the Surface of the Earth, woud occupy 6 Times its former Space: supposing the Air both below and above to be of the same Kind, as well as of the same mean Temperature of 55, on the Thermometer. See “Martin’s Philosophical Grammar, Page 178.”
[85]Chalmer describing a Whirlwind, which is a Storm of collection and Ascent of hot Air, &c. by Rarefaction, says, “as the Wind ceased, presently after the Whirlwind passed, the branches and Leaves of various Sorts of Trees, which had been carried into the Air, continued to fall for half an hour; and, in their Descent, appeared like Flocks of Birds of different Sizes.”
This Circumstance proves that Columns of hot Air must have been raised in a Body, in Succession, to so considerable a Height, that Branches of Trees carried up by them, took half an Hour in falling.
[86] It may be from this Principle, that in the East, Liquids are kept cool by being hung in the Shade, in the open Air, suspended in wet Cloths: there being a continual Breeze and Succession of cool dry Spunges (as it were) of Air, in Contact with the wetted Cloths, whose Moisture will thus be more quickly evaporated.
[87] Historia Ventorum, Pag. 48, Art. 33.
[88]“Cum enim (Venti) Choreas ducant, Ordinem Saltationis nosse jucundum fuerit. Art. 18.”
[89]On the Action of the Sun and Moon over Animal Bodies, by Dr. Mead, Miscell. Cur. Vol. 1. P. 372, 373.