142. Air may alfo be faid to be the feminary of minerals and metals, as it is of vegetables. Mr. Boyle informs us, that the exhausted ores of tin and iron being expofed to the air become again impregnated with metal, and that ore of alum having loft it's falt recovers it after the fame manner. And numberlefs inftances there are of falts produced by the air, that vaft collection or treasury of active principles, from which all fublunary bodies feem to derive their forms, and on which animals depend for their life and breath.

143. That there is fome latent vivifying fpirit difperfed throughout the air common experience fheweth; inafmuch as it is neceffary both to vegetables and animals (b) whether terreftrial or aquatic, neither beafts, infects, birds, nor fifhes 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 though the air fhould retain it's elafticity; which, by the bye, is an argument that air doth not act only as an antagonist to the intercoftal mufcles. It hath both that and many other ufes. It gives and preferves a proper tone to the veffels: this elaftic fluid promotes all fecretions: it's ofcillations keep every part in motion it pervades and actuates the whole animal fyftem, producing great variety of effects, and even oppofite in different parts, cooling at the fame time and heating, diftending and contracting, coagulating and refolving, giving and taking, fuf taining life and impairing it, preffing without anđ expanding within, abrading fome parts, at the fame time infinuating and fupplying others, producing various vibrations in the fibres, and fer

(b)* 138, 139%

ments

ments in the fluids; all which muft needs enfue from fuch a fubtile, active, heterogeneous and elaftic fluid.

144. 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, though men are not agreed, yet it is agreed, it must be the same thing that fupports the vital and the common flame; it being found that when air, by often breathing in it, is become unfit for the one, it will no longer ferve for the other. The like is obfervable in poifonous damps or fteams, wherein flame cannot be kindled. As is evident in the Grotto del cane near Naples. And here it occurs, to recommend the plunging them into cold water, as an experiment to be tried on perfons affected by breathing a poisonous vapour in old vaults, mines, deep holes or cavities under ground. Which, I am apt to think, might fave the lives of feveral, by what I have feen practifed on a dog convulfed, and in all appearance dead, but inftantly reviving on being taken out of the abovementioned Grotto and thrown into a lake adjacent.

145. Air, the general menftruum and feminary, feemeth to be only an aggregate of the volatile parts of all natural beings, which variously combined and agitated produce many various effects. Small particles in a near and close fituation strongly act upon each other, attracting, repelling, vibrating. Hence divers fermentations, and all the variety of meteors, tempefts, and concuffions both of earth and firmament. Nor is the microcofm lefs affected thereby. Being pent up in the vifcera, veffels, and membranes of the body, by it's falts, fulphurs, and elaftic power, it engenders cholics, fpafms, hyfteric disorders and other maladies.

146. The specific quality of air is taken to be

I 2

permanent

permanent elafticity. Mr. Boyle is exprefly of this opinion. And yet, whether there be any fuch thing as permanently elaftic air may be doubted, there being many things which feem to rob the air of this quality, or at leaft leffen and fufpend it's exertion. The falts and fulphurs, for inftance, that float in the air abate much of it's elafticity by their attraction.

147. Upon the whole it is manifeft, that air is no diftinct element, but a mass or mixture of things the most heterogeneous and even oppofite to each other (m), which become air, by acquiring an elasticity and volatility from the attraction of fome active, fubtile fubftance; whether it be called fire, æther, light, or the vital fpirit of the world; in like manner as the particles of antimony, of themfelves not volatile, are carried off in fublimation and rendered volatile, by cohering with the particles of fal ammoniac. But action and reaction being equal, the fpring of this æthereal fpirit is diminished by being imparted. It's velocity and fubtilty are also lefs from it's being mixed with groffer particles. Hence found moves flower than light, as mud than water.

148. Whether air be only freed and fixed, or generated and destroyed, it is certain that air begins, and ceafes to exert or fhew itfelf. Much by experiments seems to be generated, not only from animals, fruits, and vegetables, but also from hard bodies. And it is obferved by Sir Ifaac Newton, that air produced from hard bodies is most elastic. The tranfmutation of elements, each into other, hath been anciently held. In Plutarch we find in was the opinion of Heraclitus, that the death of fire was a birth to air, and the death of air a birth to water. This opinion is alfo maintained by (m) 137, 145.

Sir

Sir. Ifaac Newton. Though it may be queftioned, whether what is thought a change be not only a disguise.

149. Fire feems the most elaftic and expanfive of all bodies. It communicates this quality to moist vapours and dry exhalations, when it heats and agitates their parts, cohering closely with them, overcoming their former mutual attraction, and caufing them, inftead thereof, reciprocally to repel each other and fly asunder, with a force proportionable to that wherewith they had cohered.

150. Therefore in air we may conceive two parts, the one more grofs which was raifed and carried off from the bodies of this terraqueous mass: the other a fine fubtile spirit by means whereof the former is rendered volatile and elaftic. Together they compofe a medium, whofe elafticity. is less than that of pure æther, fire, or fpirit, in proportion to the quantity of falts, vapours, and heterogeneous particles contained therein. Hence it follows, that there is no fuch thing as a pure fimple element of air. It follows alfo, that on the higheft mountains air fhould be more rare than in proportion to the vulgar rule, of the spaces being reciprocally as the preffures: and fo in fact it is faid to have been found, by the gentlemen of the French Academy of Sciences.

151. Æther, fire, or fpirit being attracted and clogged by heterogeneous particles becometh lefs active; and the particles cohering with thofe of æther, become more active than before. Air therefore is a mafs of various particles, abraded and fublimated from wet and dry bodies of all forts, cohering with particles of æther; the whole permeated by pure æther, or light, or fire: for thefe words are used promifcuously by ancient philofophers.

152. This

152. This æther or pure invifible fire, the moft fubtile and elaftic of all bodies, feems to pervade and expand it felf throughout the whole universe. If air be the immediate agent or inftrument in natural things, it is the pure invifible fire that is the first natural mover or fpring, from whence the air derives it's power (a). This mighty agent is every where at hand, ready to break forth into action, if not reftrained and governed with the greateft wifdom. Being always reftless and in motion, it actuates and enlivens the whole vifible mafs, is equally fitted to produce and to deftroy, diftinguishes the various ftages of nature, and keeps up the perpetual round of generations and corruptions, pregnant with forms which it conftantly fends forth and reforbs. So quick in it's motions, fo fubtile and penetrating in it's nature, fo extenfive in it's effects, it feemeth no other than the vegetative foul or vital spirit of the world.

153. The animal fpirit in man is the inftrumental or phyfical caufe both of fenfe and metion. To fuppofe fenfe in the world, would be grofs and unwarranted. But loco-motive faculties are evident in all it's parts. The Pythagoreans, Platonifts, and Stoics held the world to be an anim. Though fome of them have chofen to confider it as a vegetable. However the phænomena and effects do plainly fhew there is a spirit that' moves, and a mind or providence that prefides. This providence, Plutarch faith, was thought to be in regard to the world, what the foul is in regard to man.

154. The order and courfe of things, and the experiments we daily make, fhew there is a mind that governs and actuates this mundane fyftem, (a) 139, 149, 158.

as