⚫of vapours or dry exhalations, are rais'd from the earth, water, minerals, vegetables, animals, &c. either by the folar, fubterraneous, or culinary Fire.'

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27. Elementary Air properly fo called, is a certain fubtle homogeneous elaftic matter, the bafis or fundamental ingredient of the atmospherical Air, and that which gives it its denomination.'

28. The peculiar nature of this pure 2⚫therial Matter we know but little of; what Authors have advanced concerning it being chiefly conjectural. We have no way of examining it apart, or feparating it from the • other heterogeneous Matters it is mixed with, and confequently no way of afcertaining with ⚫ evidence what belongs to it abftractedly from • the reft.'

29 Dr. Hook and fome others will have it to be no other than the Æther itself, or that fine, fluid, active Matter, diffus'd thro the whole expanfe of the celeftial regions; which coincides with Sir Ifaac Newton's Subtile Medium or Spirit.'

30. In this view it is fuppofed a Body, fui generis, ingenerable, incorruptible, immuta⚫ble, present in all places and in all bodies.'

31. I alfo confulted the learned Bishop Berkeley's Siris, where he appears to have taken great pains in examining the nature and properties of the Atmosphere, and adopted many of the opinions of the ancients on the fame.

32. At Section 137, he tells us, that, the Air or Atmosphere, that furrounds our earth, contains a mixture of all the active volatile parts of the whole habitable world; that is, of all vegetables, minerals, and animals. Whatever perspires, corrupts, or exhales, impregnates the Air, &c.

33. The perpetual ofcillations of this • elastic and restless element operate without Sceafing on all things that have life, whether animal or vegetable, keeping their fibres, veffels, and fluids in a motion always changing, as heat, cold, moisture, drynefs, and ' other causes, alter the elasticity of the Air which accounts, it must be own'd, for many effects. But there are many more which must be deriv'd from other principles or qualities in the air. Thus iron and copper are ⚫ corroded and gather ruft in the air, and bo• dies of all forts are diffolv'd or corrupted, which fheweth an acid to abound and diffuse • itself throughout the air. Sect. 138.

34. By this fame air, Fire is kindled, the lamp of life preferv'd, refpiration, digestion, nutrition, the Pulfe of the Heart, and motion of all the Muscles feem to be performed. Air therefore is a general agent, not only exerting its own, but calling forth the qua lities or powers of all other bodies, by a divifion, comminution, and agitation of their particles, causing them to fly off, and become volatile and active. 139.

35. Nothing ferments, vegetates, or pu trefies without air, which operates with all the virtues of the bodies included in it, that ⚫ is, of all nature; there being no drug, falutary or poisonous, whofe virtues are not breathed into the air. The Air therefore is ⚫ an active mass of numberlefs different principles, the general fource of corruption and generation; on one hand dividing, abrading, and carrying off the particles of bodies, that is, corrupting, or diffolving them; on the other, producing new ones into being, de• ftroying and beftowing forms without inter• miffion. 140.

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36. The feeds of things feem to lye latent in the air, ready to appear and produce their kind, whenever they light on a proper matrix. The extremely small feeds of fern, • moffes, mushrooms, and fome other Plants, ⚫ are concealed, and wafted about in the Air, every part whereof feems replete with feeds of one kind or other. The whole atmosphere ⚫ feems alive. There is every where acid to corrode, and feed to engender. Iron will ruft, and mould will grow in all places. Virgin-earth becomes fertile; crops of new plants ever and anon fhew themselves; all which demonftrates the Air to be a common feminary and receptacle of all vivifying prin•ciples.' '141.

37.

That there is fome latent vivifying fpirit difpers'd throughout the air, common

C 2

expe

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⚫ experience fheweth; inafmuch as it is neceflary both to vegetables and animals, whe ther terreftrial or aquatic,neither Beafts, Infects, Birds, nor Fishes, being able to fubfift without air. Nor doth all Air fuffice, there being fome quality or ingredient, of which, when air is deprived, it becometh unfit to maintain either Life or Flame. And this, even tho' the air fhould retain its elasticity; which by the bye, is an argument that Air doth not act only as an antagonist to the intercostal mufcles. It hath both that and many other uses. It gives and preferves a proper tone to the veffels: This elaftic fluid promotes all fecre tions: Its ofcillations keep every part in motion: It pervades and actuates the whole animal fyftem, producing great variety of effects, and even oppofite at different parts, cooling and heating at the fame time, dif tending and contracting, coagulating and refolving, giving and taking, fuftaining Life ⚫ and impairing it, preffing without and expanding within, abrading fome parts, at the ⚫ fame time infinuating and fupplying others, producing various vibrations in the Fibres, ⚫ and ferments in the Fluids; all which must needs enfue from fuch a fubtile, active, heterogeneous and elastic fluid.' 143.

38. But there is, as we have obferved, • fome one quality or ingredient in the air, on which Life more immediately and principally depends. What that is, tho' Men are

' not

not agreed, yet it is agreed, it must be the fame thing that fupports the vital and the common flame, it being found, that when air, by often breathing in it, is become un• fit for the one, it will no longer ferve for the other, &c. &c. 144.

39. N. B. This and much more to the fame effect is contain'd in the Bishop's Siris, or effay on the virtues of Tar-water.

40. When I had perus'd the above account, concerning fuch remarkable properties of the atmosphere, it appear'd, efpecially at first, quite incredible; particularly where he endeayours to fhew, that the Air by virtue of atherial Fire contain'd therein, includes the fpermatic forms of all natural things : —— The feeds of things feem to lye latent in the air, ready to appear and produce their kind :— that every part of the air feems replete with feeds of one kind or other: that the • Element of ætherial Fire or Light seems to comprehend in a mix'd state, the Seeds, the natural Causes and Forms of all fublunary Things,' and the like.

41. Not being accuftom'd to fuch kind of Reafoning, it appear'd fo extravagant, that I thought to have paffed over that part without farther notice.

42 But when I confulted the renown'd Boerhaave on the fame Subject, I was foon made fenfible of my mistake; for he not only confirms what I thought fo improbable in general,

but