PNEUMATICS what fhews it was not the clofenefs of the veffel, but the fudden exfuction of the air, that killed thofe creatures fo foon; we once inclos'd a bird in a fmail receiver, where, for a while, he eat very chearfully fome feeds that we convey'd in with him; and not only liv'd ten minutes, but had, probably, furviv'd much longer, tho' he had not been refcu'd. Another bird being, within half a minute, caft into violent convulfions, upon the exfuction of the air; we haftily turn'd the ftop-cock, to let it in again, whereby the gafping animal was prefently recover'd. And, at another time, we, at night, fhut up a bird in one of our small receivers, and obferv'd, that, for a while, he was fo infenfible of the alteration of the air, that he fell afleep, with his head under his wing; and tho' he afterwards awaked sick, yet he continued upon his legs, for above forty minutes; and then seeming ready to expire, we took him out, and foon found him lively. Upon the whole, there appears reafon to fufpect, that there is fome ufe of the air, which we do not yet thoroughly underftand, that makes it fo necessary to the life of animals.

Paracelfus, indeed, tells us, that " as the ftomach concocts the aliment, ແ and makes part of it useful to the body, rejecting the other; fo the lungs confume part of the air, and reject the reft." Whence, according to him, we may fuppofe a little vital quinteffence in the air, which ferves to refresh and reftore our vital fpirits; for which purpofe, the groffer, and far greater part of the air, being unferviceable, it is not ftrange that an animal fhould inceffantly require fresh air. This opinion, indeed, is not abfurd; but it requires to be explain'd and prov'd: befides, fome objections may be made to it, from what has been already argued against the tranfmutation of air, into vital fpirits. Nor is it probable, that the bare want of the generation of the ufual quantity of vital spirits, for less than one minute, fhould be able to kill a lively animal, without the help of any external violence. And, upon this fuppofition, Cornelius Drebell, is affirm'd, by many credible perfons, to have contrived a veffel to be row'd under water: for Drebell conceiv'd, that it is not the whole body of the air, but a ccrtain spirituous part of it, that fits it for refpiration; which being spent, the remaining groffer body of the air, is unable to cherish the vital flame refiding in the heart. So that, befides the mechanical contrivance of his boat, he had a chymical liquor, which, by unftopping the veffel wherein it was contain'd, the fumes of it would fpeedily reftore to the air, foul'd by refpiration, fuch a proportion of vital parts, as would make it again fit for that office; and having made it my bufinefs to learn this ftrange liquor, his relations conftantly affirm'd, that Drebell would never difclofe it, but to one perfon, who himself told me what it was. I have, therefore, been fometimes, inclined to fuppofe, the air neceffary to ventilate and cherish the vital flame, which fome imagine to be continually burning in the heart: for that, in our engine, the flame of a lamp will vanifh almoft as foon after the exfuction of the air, as the life of an animal. We have made a hard body, in the form of a clove, but twice as long, and proportionably thick, of fuch a compofition, that if it be kindled at the upper end, it will

moft

moft certainly burn away to the bottom, much better than a match: this PNEUMATICS. we often convey'd, kindled at the upper end, into a small receiver; but ftill found, that tho' presently, upon the exfuction of the air, it would leave fmoking, and feem quite gone out; and again begin to fmoke, as foon as the air was let in upon it; yet, if the air were kept out but four or five minutes, the fire would be totally, and irrecoverably extinguifh'd. And, conveying a small lamp into a large receiver, with highly rectified spirit of wine, we could not, upon feveral trials, make the flame laft two minutes, after the air was began to be drawn out. This latter opinion, however, has its difficulties: for tho', in the hearts of many animals, the blood be a warm liquor, and, in fome, even hot; yet it is hard to conceive either how the air can get thither; or how, in cafe it could, it fhould increase the heat: fince, however the air may increase the heat of a coal, by blowing off the afhes, and making the active corpufcles penetrate farther into the kindled body, and fhatter it the more; yet hot liquors have their heat allay'd, by air blown on them. And, fince fome naturalifts think the heat. refiding in the heart, to be a true flame, but temperate as the flame of spirit of wine; which will long burn upon fine linen, or paper, without confuming them; I wish they had been more curious to make different trials: with that liquor. For the flame of highly rectified spirit of wine, will not only confume paper, and linen; but I have used it in lamps, to diftil liquors out of tall cucurbits, and found that it gave, at least, as great a heat, as oil: nay, I have readily melted crude gold, with the bare flame of this fpirit.

c

Dr. Harvey demands, "why a fœtus, even out of the womb, if involv❜d in the fecundines, may live, for a confiderable time, without refpiration; yet, if after having once began to breathe, its refpiration be ftop'd, it presently dies?" We pretend not to folve this problem, but made the following experiment with a view to it. We caus'd a bitch to be ftrangled,, that was almoft ready to whelp; and prefently opening her, found four puppies; one of which we freed from the coats that involv'd him, and from the liquor wherein he fwam, and obferved, that he quickly open'd his mouth very wide, mov'd his tongue, and exercis'd refpiration. Then we open'd both his abdomen, and cheft, and cut the diaphragm afunder; notwithstanding which, he feem'd often to endeavour at refpiration, and. remarkably mov'd the intercoftal muscles, part of the diaphragm, the mouth and tongue. But being defirous to try whether the other young ones, that had not yet breath'd at all, would long furvive this; we took them out, and having open'd them, found none of them fo much alive as to have any perceptible motion in their hearts; whereas the heart of that which had once enjoy'd the benefit of refpiration, continued its motion fo long, that we obferv'd the auricle to contract, after five or fix hours; and it. continued about two hours longer.

It is much doubted, whether fish breathe under water. That fuch as are not of the whale kind, have no refpiration, as 'tis exercifed by beafts, and birds, may be argued from their having no cavity in their hearts, and from

PNEUMATICS their want of lungs, whence they are obferv'd to be mute; unless we fay, that their gills answer to lungs. But that air is neceflary even to the lives of fish; and that therefore, 'tis probable, they have fome obfcure kind of refpiration, feems manifeft from obfervations, and experiments. Several authors tell us, that fish foon die in ponds, and glaffes quite fill'd with water, if the one be fo frozen over, and the other fo clofely ftop'd, that they cannot enjoy the benefit of the air. And our engine hath taught us, that many little parcels of interfperfed air, lurk in water; and this, perhaps, fifh may make fome ufe of.

Removing a large eel, out of a veffel of water, into our great receiver, we caufed the air to be evacuated, and obferv'd, that after fome motion in the glass, she feem'd fomewhat difcompofed, and, at length, turn'd up her belly, and afterwards lay altogether movelefs, as if quite dead; but upon taking her out of the receiver, fhe fhew'd herself as much alive as before. But, indeed, a large grey houfe-fnail, being clos'd up in one of our fmall receivers, neither fell down from the fide of the glass, upon drawing out the air; nor was fo much as depriv'd of progreffive motion thereby: tho', except this, we never put any living creature into our exhausted receiver, but what gave figns of death.

Hippocrates, and fome learned phyficians of late, fuppofe, that a fœtus refpires in the womb; but it feems very difficult to conceive how air fhould traverse the body of the mother, and the teguments of the child : and fince nature hath, in new-born infants, contrived peculiar temporary veffels, that the blood may circulate thro' other paffages, than it does in the fame individuals, when they come to have the free ufe of their lungs, 'tis improbable that the foetus in the womb fhould properly refpire: but, then, fince our experiments have manifefted, that almost all kinds of liquors, as well as water, abound with interfperfed corpufcles of air, it seems not altogether abfurd, that when the fœtus is grown big, it may exercise fome obfcure refpiration; efpecially fince children have been heard to cry in the mother's womb. And I know a young lady, whofe friends, when the once went with child, complain'd to me, that he was feveral times much frighted with fuch cries; which, till I difabufed her, fhe, and her friends, look'd upon as portentous. And 'tis no very unfrequent thing, to hear the chick pip in the egg, before the fhell is broken. This, however, I only bring as a probable argument, till I can difcover whether the motion of a rarified fubftance, tho' no true air, may not, at the top of the larynx, produce a found; fince the blade of a knife, held in feveral poftures, in the ftream of the vapours that iffues out of an xolipile, will afford various and audible founds. I have, alfo, had thoughts of trying to make a large receiver, with little glafs windows, capable of holding a man, who may obferve several things as to refpiration, &c. and, in cafe of fainting, may, by giving a fign, be immediately relieved with fresh air. And it feems not impoffible, that fome men, by use, may bring themselves to fupport the want of air a pretty while; fince we fee that feveral will live much longer than others under water. Those who dive for pearls in

very

the

the Weft-Indies, are reported to be able to ftay a whole hour under water: PNEUMATICS. and Cardan tells us of one Colanus, a diver in Sicily, who was able to continue there three or four times as long. We have, alfo, often feen in England, a corpulent man, who defcends to the bottom of the Thames, and thence brings large fish, alive in his hands, out of deep holes; as Acofta tells us, he faw in Peru, the like manner of fishing practifed by the Indians.

However, there are but few men, who, even by use, can fupport, for many minutes, the want of air: a famous diver, of my acquaintance, tells me, that at the depth of 50 or 60 feet under water, he cannot continue above two minutes, without reforting to the air which he carries down with him in an engine. He, alfo, told me, that by the help of fpunges dip'd in oil, and held in his mouth, he could much longer fupport the want of refpiration, under water, than without them: the true caufe of which, would, perhaps, if difcover'd, hint the nature of refpiration in fish. But the neceffity of air to the greatest part of animals, unaccuftomed to the want of it, may be beft judg'd of by the following experiment. We convey'd a bee, a flesh-fly, and a palmer-worm, into one of our small. receivers, and, upon exhaufting thereof, obferv'd, that the bee and the fly fell down, and lay with their bellies upwards, and that the worm seem'd to be fuddenly ftruck dead; all of them lying without motion, or any other difcernible fign of life, in less than one minute; notwithstanding the smallnefs of the animals, in proportion to the receiver, which, too, was not free from leaks: but we had no fooner re-admitted the air, than all the three infects gave figns of life, and, by degrees, recover'd. When we had again drawn out the air, their motions presently ceased, and they fell down, seemingly dead, as before; continuing movelefs, as long as, by pumping, the vessel was kept exhaufted. Herein appears the wife conduct, and goodness of the creator, who, by giving the air a fpring, hath made it very difficult to exclude a thing fo neceffary to animals. And here we may fufpect, that if infects have no lungs, nor any part anfwering thereto, the ambient air affects, and relieves them, at the pores of their skin; for, as Hippocrates well faid, " a living body is every where perfpirable." Thus the moifter parts of the air readily infinuate themselves into, and recede from the pores of the beards of wild oats, and of other wild plants, which almost continually wreath and untwift themselves, according to the lighteft variations in the temperature of the air.

We, particularly, took notice in this experiment, that, when, at any time, upon the re-admiffion of the air, the bee began to recover, the firft fign of life fhe gave, was a vehement panting, which appear'd near the tail; the like we have obferv'd in bees drown'd in water, when they first come to be revived, by a convenient heat; as if the air were, in one cafe, as proper to fet the fpirits, and alimental juice in motion, as heat, in the

other.

This experiment, alfo, feems to manifeft, that, even living creatures,. man always excepted, are a kind of very curious machines. For, here we fee animals lively, and perfectly found, immediately deprived of motion,

and

per

PNEUMATICS. and all difcernible figns of life, and reduced to a condition that differs from death, only, in being not abfolutely irrecoverable: and this is form'd without the leaft external violence, more than is offer'd to a windmill, when, the wind ceafing to blow on the fails, all the feveral parts remain moveless, and useless, till a new breeze puts them again into motion.

Whether the action of men

'Tis known, that bees, and fome other infects, will walk, and fly, for a great while after their heads are off, and fometimes one half of the body will, for feveral hours, walk up and down, when it is fever'd from the other; yet, upon the exfuction of the air in this experiment, not only the progreffive motion of the whole body, but the very motions of the limbs immediately ceafe; as if the air were more necessary to these animals, than their own heads.

But, in these infects, that fluid body, in which life chiefly refides, feems nothing near fo diffipable, as in perfect animals. For, the birds convey'd into our fmall receiver, were, within two minutes, brought paft recovery; but, we were unable to kill our infects, by the exfuction of the air for, tho' as long as the pump was kept working, they continued immoveable, yet, when that refted, the air, which prefs'd in, at the unperceiv'd leaks, flowly reftored them to the free exercife, and functions of life. Without denying, then, that the air may be, fometimes, very ufeful, by condenfing, and cooling the blood, that paffeth thro' the lungs; I am of opinion, that the depuration of that animal fluid, is one of the ordinary, and principal ufes of refpiration.

42. Having entertain'd a fufpicion, that the action of corrofive liquors fruums depends in diffolving bodies, may be confiderably varied by the gravitation, or prefupon the preffure fure of the incumbent air, and the removal of it; I examined my conjecof the air. ture by the following experiment.

I caft ten whole pieces or fprigs of red coral, into as much spirit of vinegar as reach'd an inch above them; then putting thefe, together with the menftruum, into a long-neck'd vial, whereof they scarce fill'd a third part, we convey'd that vial into one of our small receivers, and having faften'd on the cover, we let the liquor remain unmov'd a while. But finding, there only arofe, as before, a number of fmall bubbles, that caufed no fenfible froth upon the furface of the vinegar; we made two or three exfuctions of the air, upon which there rofe, from the coral, fuch a multitude of bubbles, as made the whole body of the menftruum appear white; and foon after, yielded a froth, equal in magnitude to the reft of the liquor the menftruum plainly appearing to boil: tho', if we defifted but one minute from pumping, the decrease of the froth, and ebullition, upon the getting in of a little air, at fome leak or other, feem'd to argue, that the removal of the preffure of the external air, gave occafion to this effervefcence. But, for farther fatisfaction, we let in the external air at the ftop-cock, when, immediately, the froth vanifhed; and fo many of the bubbles, within the body of the liquor, difappear'd, that it loft its whitenefs, and became tranfparent again; the menftruum, alfo, working as languidly upon the coral, as before they were put into the receiver: but,

when