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too by Lead in the Test. But when Cobalts, Arsenics, and the like rapacious Sulphurs,

are intimately united with Gold and silver Ore, the particles of the Ore being by this

means render'd yolatile, when they come to * the Fire, they carry away these noble Metals

to that degree, that to the great damage of ' the Owner, a good part of them both is lost, 'which by a gentle calcination, and the ad* dition of some fixing Powders, might be entirely presery'd. Hence, therefore, it

appears, what an abundance of Gold and « Silver

may
be raifed

up

into the air. Nothing, indeed, seems a greater Paradox, than 'volatile Gold, and yet we are certain from • undeniable chymical Experiments, that if

you take common fublimate of Mercury, 6 and rub it well with Gold reduc'd to Pow

der, and then distill it in a Retort with re

gulus of Antimony, the very Body of the • Gold will ascend in form of a red Oil, and • become perfectly volatile. By Sulphur like« wise, calcin'd Vitriol, and Sal-ammoniac, ' mix'd and apply'd according to Art, almost • all Metals may be render'd volatile in the • Fire. No wonder then, that in clear Wea• ther, there very often appears about Mines $ sudden Fumes, which extinguish the Light ? of a Torch. See Boyle's Works. vol. ist,

p. 52. Since even the most dense Bodies may; • in the form of a Fume, be so carried up into the air, as that it can hardly be deterd. min'd what Bodies they were. But there is

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another Cause which is frequently concerned • in this Affair, and which likewise imprega

nates the Air with these metallic parts, and

that is the Air it self abounding with Salts . and Sulphurs. For as I have already thewn • above that the whole Air is full of Salts • and Sulphurs, and as it appears from what

I have now deliver'd, that those Salts and • Sulphurs can carry aloft even Metals them. felves when they are dissolv'd, it is easy to

apprehend, that the Air it self can by this • means effect that the parts of Metals may • be suspended and float about in it.' 45

Before we leave the examination of • the various Bodies, that are contained in the * Air, and of the different Powers which

pre• vail in it, we must yet take under conside. ration one quality of it, which is very salutary and necessary to the Life of Animals

and Vegetables; a quality which has not yet • been accounted for from any other property • of the Air; but by a diligent inquiry, howa • ever, may pofsibly, hereafter, be come at the • Knowledge of. Whether, now, this latent • virtue of the Air is actually drawıı out of it

by Animals and Vegetables, and hence is in é a short Time exhausted and consumed; and • whether, when it does thus fail, the Ani• mal dies, no body is, I think at present, able • to determine. This however is certain, that if a small Bird is put into a large Receiver D

6 full

a

full of common cold Air, and the Receivet " is then very closely stopp'd, the Bird will

grow sick and vomit within a quarter of an hour, and die in the space of half an hour after. Boyle on the Air. p. 184. A Fish

kept in Water, in a vessel wel} closed, with* out renewing the Air, dies in a short time. Fish likewise die in ponds, that are every

where frozen over, and quickly perish Sin Water, out of which the Air is exhausted.

Hift. de l'Acad. Roy. des Scien. 1699. 240. 1701. 46. and Mem. 224.- Flame, and

red hot coal, quickly go out in air, that is close pent in. The little Eggs of any Insects • whatever, being accurately stopt up in glass

vessels, do not produce their young, though ' affisted by a kindly warmth. The Seeds of • Plants likewife duly moistened, and sow'd « in the best Earth in close Glasses, do not grow, or give any signs of active Life, tho' excited

by a due degree of heat. On the other hand, ' the upper surface of Blood, that is expos’d to • the Air, is of a bright scarlet colour, whilst

other
part,

where the air don't come at it, it grows as black as the juices of a Cuttie-filh: And yet, as soon as ever this black

part is laid open to the air, the black colour ' is inmediately chang'd again into a scarlet:

in every

All these experiments then make it appear, " that there is in the air a certain hidden vir

tue, which cannot be accounted for from the properties of the air, which have been his

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therto discover'd. Sendivogius maintain’d it openly, that there lies hid in the air, the • occult' Food of Life; and other Chymists « have asserted the fame: But what that is, s or how it acts, or what is the proper effect • of it, is a matter still in the dark, Happy the

Person that shall happen to discover it. Let this hipt suffice for Persons that are ignorant

of it, Is it not the elastic Part of the Air « alone?!

46. For my own part, I confess, I cannot apprehend, that either the natural Philosophers, or Physicians, have yet discover'd the physical cause of this wonderful quality of air. I have feen indeed a great many conjec

tures upon it; but they have almoft all fallen • of themselves.' Dallow's Translation of Boerhaave's Theor. of the Art of Chym. p. 292.

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CHAP. II.

PART 1.

SECTION 47.

Sir Isaac Newton's Rules of Reasaning

in Philosophy. And, the Author's First Principles.

*FTER having consulted those ree

A A spectable Authors, mentioned in the a preceding Chapter, upon Air, and

throughly and strictly examined the electrical Fluid, by means of the most effectual Experiments, that I could either meet with or invent, and varied and changed them into many different forms, I diligently compared the electrical fluid with the description that had been given of air; and considering the whole with the utmost attention and accuracy, I was convinced of the truth of many things, which they had advanced, since it was no morą than I myself saw vețified at the electrical apparatus.

48. When a Writer undertakes to explain and settle any important point, which before was doubtful, his First Principles should be rational, and his Method perspicuous: In order to which, I shall lay down my first and funda

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