PNEUMATICS However, we ftill ply'd the pump, drawing out, together with the air, much fulphureous, and offenfive fmoke; whereby, though the flame feemed fomewhat gradually impair'd, yet it manifeftly continued burning much longer than, by the fhort duration of other flames in our receivers, one could expect. And once, particularly, in making this experiment, the flame lafted, till the receiver was judg'd to be thoroughly exhaufted; and fome thought it fo furviv'd the exhauftion, that it went not out for want of air-fewel; the brimftone appearing, when we took off the receiver, either to have been confumed by the fire that fed on it, or to have casually ran off from the iron, the heat whereof had kept it conftantly melted. 60. Having obtain'd a faline fpirit, which, by an uncommon way of preparation, was made exceeding sharp, and piercing, we put into a vial, capable of containing three or four ounces of water, a convenient quantity of new filings of pure fteel; which, being moiften'd in the vial, with a little of the faline menftruum, were, afterwards, drench'd with more; whereupon the mixture grew very hot, and yielded large and fetid fumes. And fo inflammable was this fmoke, that upon the approach of a lighted candle, it would readily take fire, and burn with a bluish, and somewhat greenish flame, at the mouth of the vial, for a confiderable time together; and that, tho' with a little light, yet with more strength than one would eafily fufpect. A durable flame of a metalline fubftance in va cuo. The flame of Spirit of wine impregnated with a metal in vacuo. This flaming vial, therefore, we convey'd into a receiver, which he who ufed to manage the pump affirm'd, would be exhaufted by about fix exfuctions; and the receiver being well cemented on, upon the firft fuck, the flame fuddenly appear'd four or five times as great as before; because, as we fuppofed, upon the withdrawing of the air, and, confequently, the weakning of its preffure, numerous bubbles were produced in the menftruum; which breaking, fupply'd the neck of the vial with inflammable fteams; and thefe, we thought, took fire, with fome noife. Upon the fecond exfuction of the air, the flame blazed out, as before; and so it, likewife, did upon the third; but, after that, it went out: nor could we rekindle any fire, by fuddenly removing the receiver; only we found, that there remain'd fuch a difpofition in the fmoke to inflammability, that holding a lighted candle to it, a flame quickly ensued. 61. Having fo united highly rectified fpirit of wine with a prepared metal, that they would afford a vifible ting'd flame; we put this mixture into a small glass lamp, furnished with a very flender wieck, which the mixture would not burn, whilst there was liquor enough left to moisten it well; and putting this lighted lamp into a convenient part of a receiver, able to hold two gallons of water, we made hafte to cement on the glafs to the engine; yet found not, in two or three feveral trials, that, after the pump began to be work'd, fo little a quantity of ting'd flame lafted more than half a minute. We also obferv'd, in repeating this experiment, that when the flame began to decay, the turn-key, being now and then drawn almoft out, the ting'd flame once lafted a minute and half, and another time longer; ~ longer; that the turn-key being, from the firft, taken out, the flame lafted PNEUMATICS two minutes; that, in the fame case, a pipe being bedded in the cement, at the bottom of the glafs, and open at both ends, each almost as big as the orifice fill'd by the turn-key, the ting'd spirit seem'd to burn as if the flame would have lafted very long, had we permitted it; and laftly, that the orifice at the top being stopt with the turn-key, tho' the pipe were left open at the bottom, it plainly, in a fhort time, feem'd greatly to decay, and ready to expire; but caufing one to blow in gently at the pipe, with a pair of bellows, tho' this did not keep the flame vigorous, yet it continu'd alive for above four minutes; and then obferving it to be manifeftly stronger than it was, when we began to refresh it with the bellows, we ceas'd from blowing, and found, that tho' the glafs pipe was ftill left open, yet within about one minute the flame entirely vanish'd. 62. Eminent writers, both ancient and modern, tell us, without fcru- Flame preferple, that naptha and camphire will burn under water; but I had never the ved under good fortune to see them do fo; and doubt, these writers deliver not what water. they affirm from experience. And tho', in celebrated authors, I have met with many compofitions, that will not only burn under water, but be kindled by it; yet I found those I have had occafion to confider, to be fo lamely, or fo darkly, and fome of them, I fear, fo falfly fet down, that by the following compofition, how flight foever it may seem, I have been able to do more than with things they fpeak very promisingly of. We took of gun-powder, three ounces; of well burn'd charcoal, one dram; of good fulphur, or flour of brimstone, half a dram; of choice falt-petre, a dram and half; thefe ingredients being reduc'd to powder, and diligently mix'd without any liquor, we fill'd a large goofe-quill with it; for the kindling whereof, the open orifice of the quill or pipe, was carefully ftopt with a convenient quantity of the fame, made up with as little chymical oil, or water, as would bring it to a fit confiftence. This wild-fire we kindled in the air; and the quill, together with a weight to which it was ty'd, to keep it from afcending, we flowly let down to a convenient depth under water; where it would continue to burn, as appear'd by the great smoke it emitted, and other figns, as it did in the air; because the shape of the quill kept the dry mixture from being acceffible to the water, at any other part than the orifice; and there the stream of fired matter iffued out with fuch violence, as inceffantly beat off the neighbouring water, and kept it from entring into the cavity that contain'd the mixture, which therefore would continue burning till it was confumed. tal in vacuo. 63. In trying to kindle a combuftible fubftance in our exhausted re- An odd phenoceiver, it happen'd to fall befide the iron, whereby our intended expe- menon of the riment was defeated; but whilft we were confidering what was to be flame of a medone on this occafion, and had not yet let in the air, nor brought in the lights that were remov'd out of the room, we were furpriz'd to fee fomething burn like a pale blueish flame, almoft in the midst of the cavity of the receiver; and at firft fufpected it to be fome deception of the VOL. II. X X X fight; PNEUMATICS fight; but all the by-ftanders perceiving it alike, and obferving that it grew very broad, we look'd at it with great attention, and found it to laft much longer, than I remember to have feen any flame in an exhausted receiver. I fhould have expected that it proceeded from fome brimftone sticking, unobferv'd, to a part of the iron we had formerly employ'd to kindle fulphur, had we not, juft before, kept it red-hot in the fire. But tho' we much wonder'd whence this flame proceeded, we did not haften its extinction; and at length, when it expired of itfelf, we let in the air; and perceiv'd, upon the concave part of the iron, which we judg'd to be the place where the fame had appear'd, a piece of melted metal, fuppofed to have been faften'd to the string whereto the fewel we defign'd to kindle, had been ty'd, in order to let it down the more eafily; and this made us conceive, that the ftring happening to be burn'd, by the exceffive heat of the iron, the piece of metal fell into the cavity of it; and that by the fame heat, the more combustible part, which the chymifts call the fulphur, was melted, and kept on fire, and continu'd burning, as we have related. This piece of metal was judg'd to be lead, but having not, formerly, obferv'd fuch a difpofition in lead, to be inflam'd, I confider'd it attentively, and perceiv'd, that it was fome fragment of a mixture of lead and tin, that I caus'd to be melted in a certain proportion. Upon this account, it feems, the mixture of the ingredients had acquired fuch a new texture, as fitted the mafs to afford this odd phenomenon; which argues, that there may be flames of metalline fulphurs produc'd as eafily, without the concurrence of the air, as that of common fulphur; and continue to burn longer than that in our vacuum. Adual flame propagated with difficulty in vacuo. An attempt to make flame kindle camphire without air. 64. Having plac'd our cylindrical plate of iron, first brought to be red hot, in a receiver, capable of containing two gallons of water; and having alfo diligently pump'd out the air, we kindled a little fulphur upon the heated plate; and then a piece of dry'd fpunck, ty'd to a string, was let down to the flame. When the experiment was finish'd, and the fpunck taken out, we found it, in feveral places, not manifeftly alter'd fo much as in colour; and in thofe parts that had been noft expos'd to the flame, it was turn'd to a fubftance very different from afhes; being black, and brittle as tinder, and, like that, exceedingly difpofed to kindle upon the touch of fire. 65. Into the fame receiver, we convey'd the fame cylindrical plate of iron; and when the air had been thoroughly pump'd out, we let a piece of fuch brimftone down upon the hot iron, as would there kindle with the the help of heat. A little above this fulphur, we had ty'd to the fame ftring, a piece of camphire, that being a body exceedingly apt to take fire, or, as it were, to draw it at the flame of lighted brimftone; but our fulphur melting with the heat of the iron, dropt from the string it was faften'd to. As foon as it came to the bottom, where it was diftant from the vehement heat of the metal, the flame expired; but a part of it, that happen'd to ftick to the fide of the iron, was inflam'd by it, and the flame reach'd the camphire, without being able to make it blaze. We alfo attempted to kindle one piece of fulphur in vacuo, by the flame PNEUMATIC of another, ty'd a little lower on the fame firing, that it might firft touch the heated iron, and be thereby fet on fire; but tho' we could find nothing amifs in the kind of fulphur we then us'd, yet we were not able, even by a repeated trial, to make it take fire upon the iron; where, nevertheless, it melted, and feem'd a little to boil. A third trial was not fo unfuccefsful; for having in the receiver, well exhaufted, let down a card-match upon a very hot iron, the lower extreme of it was kindled thereby. But tho' the fulphurated part of the match thus flam'd away, yet the remaining part, which was a mere piece of card, was not thereby turn'd into flame, nor, in moft places, fo much as fenfibly fcorch'd or black'd, tho' it had been purpofely dry'd beforehand. 66. Upon a paper, laid on a convenient part of the plate of the engine, Gun-powder, we made a train of dry powder, as long as the glafs would well cover; tho' fired itthen carefully faftening on the receiver, we exactly pump'd out the air; Self, fires not the contiguous which done, we took a good burning-glafs, and about noon caft the fun- grains in vabeams thro' it, upon a part of the train; but the indifpofition of the pow- cuo. der to fire was fo great, that it fmoked, and melted, without going off. We afterwards employ'd a thinner, and more transparent receiver, which fo little weaken'd the fun's rays, that being kept obftinately upon the fame part of the train, they were able to fire feveral parts, one after another, tho' they could not caufe the flame to propagate; only thofe parts that were melted, did, at length, kindle, and fly away, leaving the reft unalter'd; fo that I found feveral little maffes of diffolv'd matter, in feveral parts of the train, with the powder unchang'd in all the others. And fome of these maffes were contiguous to grains of the powder, which both appear'd unchang'd, and kindled readily, and flash'd all away, as foon as I caus'd the burning-glafs to be applied to them in the open air. 67. For farther confirmation of fo odd an experiment, I shall add, that to try whether by the help of one of those little inftruments, wherewith the strength of powder is commonly examin'd, we could find any difference made by the abfence and prefence of the air, in the refiftance of the inftrument, or the effects of the powder on it; we faften'd it to a competently heavy, and commodioufly fhap'd weight of lead; and when it was carefully fill'd, and primed with powder, we plac'd it in a receiver of a · convenient bignefs; whence we pump'd out the air after the ufual manner, tho' perhaps with more than ufual diligence. But tho' at length, after the powder had long refifted the beams of the fun, thrown on it by a good double convex-glafs, it took fire at the touch-hcle, and fill'd the receiver with fmoke; yet this kindled powder could not propagate the flame, to that which was in the box, how contiguous foever the parcels were to one another; tho' when the inftrument was taken out into the air, where the touch hole appear'd to be free; as foon as ever new priming, with the fame fort of powder, was put in, the whole very readily went off. And when we caus'd the inftrument to be new charg'd, and upon its firing X X X 2 only PNEUMATICS Only at the touch-hole in the exhaufted receiver, order'd new priming to be added, without fo much as taking the inftrument out of the glafs; tho' afterwards this was clos'd again, but without being exhaufted, the powder, clofely fhut up in the glafs, readily went off; as well that which was in the box or cavity of the powder-tryer, as that which lay on the outward part of it. And this experiment was repeated with the like fuccefs. Two different trials with different e 68. A few corns of gun-powder being included in a very fmall bubble, freed from air, and fecur'd against the return of it, and then apply'd wa rily to coals cover'd with afhes, did neither go off nor burn; but affordvents, to kined a little yellow powder, that feem'd to be fulphur, fublimed to the updle gun-pow der in vacuo. per part of the glafs. But two larger bubbles, tho' ftrong, whereof one had the air but in part, and the other totally evacuated, being provided, each of them, with a greater quantity of powder; a while after they were put upon quick-coals, they were both blown to pieces, with a report almoft like that of a mufquet; but tho' this was done in a dark place, yet we did not perceive any real flame produc'd. relation be the Flamma Experiments, 69. We put a spoonful of highly rectify'd spirit of wine into a small fbewing the glass lamp, conveniently fhaped, and purpofely blown, with a very small twixt air, and orifice, at which we thruft in a flender cotton-wieck; we also provided a tall glass receiver, in length 18 inches, that contain'd above 20 pints of vitalis of ani- water. This receiver, which was open at both ends, had its upper orifice mals; and cover'd with a brass plate, fasten'd on very close with good cement; and mal, included for the lower orifice, which was far the wideft, we had provided a brafs with the flame plate, furnifh'd with a competent quantity of the cement we employ'd to of Spirit of keep the air out of the pneumatical engine; by means whereof, we could firft, an ani wine. fufficiently close the lower orifice of our receiver, and hinder the air from getting in at it. We then lighted up the fmall glass lamp, and plac'd it, together with a green-finch, upon the brafs-plate, and in a trice fasten'd it to the lower orifice of the receiver, and then watch'd the event; which was, that within two minutes the flame, after having feveral times almost disappear'd, was utterly extinguifh'd; but the bird, tho' for a while he feem'd to close his eyes, as tho' he were fick, appear'd lively enough at the end of the third minute, when I caus'd him to be taken out. After he had, by being kept in the free air, recover'd and refresh'd himfelf, the former trial was repeated; and at the end of the second minute the flame of the lamp went out; but the bird feem'd not to be endanger'd by being detain'd a while longer. After this, we put in, with the fame bird, two lighted lamps at once, whose flames lafted not one whole minute, before they went out together; but the bird appear'd unhurt, after having been kept five or fix times as long, before we took off the receiver. In the tall receiver, above-mention'd, we included a moufe, with a lighted lamp, fill'd with the fpirit of wine; but before the experiment was near finish'd, the moufe, being at liberty within the glafs, made fhift to |