PRZUMATICS out taking off the receiver, the manifeftly recover'd, and leap'd against the fide of the glafs; and being taken out into the open air, the flew out of my hand to a confiderable diftance. Animals in the Same parcel of air changed, as to rarity and denfity. 105. Sept. 9. Into a receiver, able to hold about 4 pints and a half of water, we convey'd a lark, together with a gage, by the help whereof we drew out of the air; then obferving the bird, we perceiv'd it to pant very much. Having continued thus for a little above a minute and a half, the bird fell into a convulfive motion, that caft it upon the back. And altho❜ we made great hafte to let in the air; yet, before the expiration of the fecond minute, preceding the convulfion, the lark was gone paft all recovery, tho' various means were used to effect it. 106. Sept. 9. Presently after, we put into the fame receiver, a greenfinch; and having withdrawn half the air, we foon began to obferve the bird, and took notice, that, within a minute after, the appear'd to be very fick; and, fhaking her head, vomited a certain fubftance against the infide of the glafs. Upon this evacuation, the bird feem'd to recover, and continue pretty well, but not without panting, till about the end of the fourth minute; when, growing very fick, fhe vomited again, but much more unquestionably than before; and, foon after, eat up again a little of her vomit; upon which, the very much recover'd. And though he had, in all, three fits of vomiting; yet, for the laft feven or eight minutes, that we kept her in the receiver, the feem'd to be much more lively than was expected: which may, in part, be attributed to a little air that, by an accident, got in, tho' it were immediately pump'd out again. At the end of a full quarter of an hour, from the first exhauftion, the bird appearing not likely to die in a great while, we took her out. 107. April 12. A new-caught viper was included, together with a gage, in a portable receiver, able to hold about three pints and an half of water. This veffel being exhaufted, and fecured against the return of the air, the animal was obferv'd, from time to time, not only to be alive, but nimbly to put out, and to draw back her tongue, for about thirty-fix hours, after fhe was fhut up: we, therefore, continued the veffel longer, in the fame fhady place; where, over-night, at the end of fixty hours. the appear'd very dull and faint, and not likely to live much longer. And, the next, 'by the afternoon, I found her ftark dead, with her mouth open'd to a ftrange widenefs; wherefore, fuffering water to be impell'd, by the outward air, into the cavity of the receiver, we found, by the water that was driven in, and afterwards pour'd out again, and measur'd, that five parts in fix of the air in the veffel, had been pump'd out: fo that in an air rarify'd, tillit expanded itself to five or fix times its ufual dimenfions, our viper was able to live fixty hours, and, perhaps, might have done fo longer. 108. In the preceding experiments, the animals were recover'd from a gafping condition, by letting in fresh air, and not the fame that had been withdrawn from them: wherefore, I thought proper, to try, whether the fame portion of air, without being renew'd, would, by being expanded much beyond its ufual degree, and reduced to it again, ferve to bring an ~ animal to near the point of expiring, and revive him again; fince, by the REUMATICS fuccefs of fuch a tryal, it would notably appear, that the bare change of the confiftence of the air, as to rarity and denfity, may fuffice to produce the above-mention'd effects. We included a moufe in a fine, limber, clear bladder, made more tranfparent by oil, rubb'd on the outfide, that the fmell of it might lefs offend the animal, to be included; clipping off as much of the bladder, at the neck, as we judg'd abfolutely neceffary for letting in a moufe: we, alfo, provided a round ftick, fomewhat lefs than the orifice; that, the wood being laid over, with a close and yielding cement, we might tye the bladder faft, and clofe enough, upon the ftopple thus fitted. In the bladder was left as much air, as we thought might fuffice him, for the time the experiment was to laft. Then, putting this limber, or dilatable receiver into an ordinary one of glafs, and, placing this engine near a window, that we might fee through both of them; the air, was, by degrees, pumped out of the external receiver, and, thereupon, the air included in the bladder proportionably expanded itself, and fo diftended the internal receiver, till, being arriv'd at a degree of rarifaction, which rendred it unfit for refpiration, I perceiv'd figns, in this animal, of his being in great danger of fudden death. Whereupon, the outward air being haftily let into the external receiver, comprefs'd the fwell'd bladder to its former dimenfions, and thereby, the included air to its former density; by which means, the moufe was quickly revived. Having given him fome convenient refpite, the experiment was repeated with the like fuccefs. prevent the ne duction or 109. We put a large parcel of tadpoles, with a convenient quantity of An attempt to water, into a portable receiver, of a round figure, and obferv'd, that, at the ceffity of respira firft exfuction of the air, they rofe to the top of the water; tho', moft of tion, by the pre them fubfided again, till the next exfuction raifed them. They feem'd, by growth of anitheir active and wrigling motion, to be very much difcompos'd. The receiver being exhaufted, they, all of them, continued moving, at the top of the water; and, tho' fome of them feem'd to endeavour to go to the bottom, and dived part of the way, efpecially with their heads, yet, they were immediately buoy'd up again. Within an hour, or a little more, they were all moveless, and lay floating on the water; wherefore, I open'd the receiver; upon which, the air rufhing in, almoft all of them presently funk to the bottom, but none of them recover'd life. 110. We, afterwards, included a lefs number of tadpoles in a smaller glafs, which was alfo exhaufted, with the like circumftances, as the former. And, when I found the other tadpoles to be dead, I hafted to thefe, which did not, except, perhaps, one, give any figns of life; but, upon letting in the air, these having not been long kept from it, fome few of them recover'd, and fwam up and down lively enough; tho', after a while, these alfo died. III. I repeated the fame experiment in a portable receiver, of a convenient kind; and, tho', after the exhauftion was perfected, the tadpoles, for a while, moved briskly enough, on the top of the water, only; yet, Zzz 2 at PNEUMATICS. "at the end of an hour, they seem'd to be, all of them, quite dead, bu continu'd floating. And, though, within half an hour after that, I let in the air; yet all the effect of it was, that the most of them, immediately funk to the bottom, as the reft, foon after, did; none of them, that I could obferve, recovering vital mo tion. The expansion of the blood and ther animal fluids. 112. We procur'd, by preferving fome rain-water, four or five of thofe odd infects, whereof gnats have, by fome, been obferved to be generated about the end of Auguft, or beginning of September. Thefe, for fome weeks, live all together in the water, as tadpoles do; fwimming up and down therein, till they are ripe for a tranfmigration into flies: but including them, with fome of their water, in a small glafs-receiver, which being exhaufted, and very exactly closed, we kept, in a fouth-window; thefe little creatures continued to fwim up and down therein, for fome few days, without feeming to be much incommoded; but at length, and all much about the fame day, they put off the habit they had, whilft they lived as fishes, and appeared with their Exuvia, or caft-coats under their feet; fhewing themfelves to be perfect gnats, that ftood, without finking, upon the furface of the water, and difcovering themfelves to be alive, by their motion, when they were excited to it; but I could not perceive them to fly in that thin medium to which inability, whether the vifcofity of the water might contribute, I know not; tho' they lived a pretty while, till hunger, or cold deftroyed them. 113. The warm blood of a lamb or a fheep, being taken as it was, immediately, brought from the butcher's, where the fibres had been broken, to hinder the coagulation, was, in a wide-mouth'd glass, put into a receiver, made ready for it; and the pump being fet on work, the air was diligently drawn out: but the operation was not always, especially at firft, fo early manifeft, as the fpirituoufnefs of the liquor would make one expect; yet, after a long expectation, the more fubtile parts of the blood would begin to force their way thro' the more clammy, and feem to boil in large clusters, fome as big as great beans or nutmegs; and, fometimes, the blood was fo volatile, and the expansion fo vehement, that it boiled over the containing glafs; of which, when it was put in, it did not fill above a quarter. 114. Having, alfo, included fome milk, warm from the cow, in a cylindrical veffel, about four or five inches high, tho' the pump was long ply'd, before any intumefcence appear'd, yet, afterwards, when the external air was fully withdrawn, the milk began to boil, in a way, that was not fo easy to defcribe, as pleasant to behold: and this it did for a pretty while, with fo much impetuofity, that it threw feveral of its parts out of the widemouth'd glass that contain'd it; tho' there were not above two or three ounces of the liquor, which only half fill'd the glafs. A yet greater difpofition to intumefcence, we thought, we obferv'd in the gall; which was but fuitable to the vifcofity of its texture. The two laft experiments were made with a design to fhew, how far the destructive operation of our engine, upon the included animals, might be be imputed the withdrawing of the air, whereby, the little bubbles gene- PNEUMATICS. rated in the blood, juices, and foft parts of the body, may, by their vaft number, and confpiring diftenfion, variously contract the veffels in fome places, and ftretch them in others; efpecially the fmaller, that convey the blood and nourishment; and fo, by choaking up fome paffages, and vitiating the figure of others, difturb, or hinder the due circulation of the blood: for, fuch diftenfions may caufe pains in fome nerves, and membranous parts, which, by irritating them into convulfions, may haften the death of animals, and deftroy them fooner by that irritation, than they would be deftroy'd by the bare abfence or lofs of what the air is necessary to fupply them with. And, to fhew, that this production of bubbles reaches, even to very minute parts of the body, I fhall add, that, I once obferved in a viper, furiously tortured in our exhaufted receiver, the creature had a confpicuous bubble moving to and fro, in the aqueous humour of one of its eyes. 115. To fhew, that not only the blood and liquors, but also the other foft parts, even in cold animals, have aerial particles latent in them; we took the liver and heart of an eel, as, alfo, the head and body of another fifh of the fame kind, cut afunder, crofs ways, beneath the heart; and putting them into a receiver, upon withdrawing of the air, we perceiv'd, that the liver manifeftly fwell'd every way; and, that both the upper part and lower of the fifh, did fo, likewife. At the place, where the divifion had been made, there came out, in each portion of the fifh, various bubbles; feveral of which feem'd to rife from the Medulla Spinalis, the cavity of the back-bone, or the adjoining parts: and the external air being let in, both the portions of the eel prefently funk; fome of the skin feeming to be grown flaccid in each. animals to fup faction made 116. We included, in a vial with a wide neck, (the whole glafs being able The power of to contain about eight ounces of water,) a fmall young moufe; then "fe to enable tyed ftrongly upon the upper part of the glafs's neck a fine thin bladder, port themselves out of which the air had been carefully exprefs'd; and convey'd this in airs by rariveffel into a middle-fiz'd receiver, in which, we alfo plac'd a mercurial unfit for refpira gage. This done, the air was, by degrees, pump'd out, till it appear'd tion by the gage, that there remain'd but a fourth part in the external receiver; whereupon, the air in the internal receiver, expanding itself, appear'd to have blown the bladder almost half full; and the moufe feeming very ill at eafe, by leaping, and otherwife endeavouring to pafs out at the neck of his prifon; we, for fear the over-thin air would difpatch him, let the air flow into the external receiver; whereby the bladder being comprefs'd, and the air in the vial reduced to its former denfity, the little animal quickly recover❜d. 117. A while after, without removing the bladder, the experiment was repeated, and the air, by help of the gage, reduced to its former degree of rarifaction; when, the moufe, after fome fruitlefs endeavours to get out of the glass, was kept in that thin air for full four minutes; at the end of which, he appear'd fo fick, that, to prevent his dying immediately, we remov'd PNEUMATIC remov'd the external, and took out the internal receiver; whereupon, tho he recover'd; yet 'twas not without much difficulty; being unable to ftand any longer upon his feet; and, for a great while after, he continu'd, ma◄ nifeftly trembling. Air, become un-‹ tion, fit for refpira its fual pref may retain 118. But, having fuffer'd him to reft for a reasonable time, prefuming that ufe had inured him to greater hardships, we convey'd him, again, into the external receiver; and, having brought the air to the former degree of rarifaction, we were able to keep him there for a full quarter of an hour; tho' the external receiver did not at all confiderably leak; as appear'd both by the mercurial gage, and by the remaining diftenfion of the bladder. And, 'tis worth noting, that, till near the latter end of the quarter of an hour, the animal fearce at all appear'd diftrefs'd; remaining ftill very quiet. And tho', when he was put in, his tremblings were yet upon him, and continu'd fo for fome time; yet, afterwards, in fpight of the expansion of the air he was then in, they foon left him. And, when the internal receiver was taken out, he not only recover'd from his fainting fooner than before, but efcaped thofe fubfequent tremblings. 119. Encouraged by this fuccefs, after we allowed him fome time to re◄ cover his ftrength, we re-convey'd him, and the vessel wherein he was included, into the former receiver, and pump'd out the air, till the mercury, in the gage, was drawn down near half an inch lower than before, that the air might be yet farther expanded. And, tho' this, at first, feem'd to difcompofe the little creature; yet, after a while, he grew very quiet, and continu'd fo for a full quarter of an hour; when, we caus'd three exfuctions more to be made, before we difcover'd him to be in manifeft danger, (at which time, the bladder appear'd much fuller than before:) but, then, we were obliged to let the air into the outward receiver; whereupon, the mouse was more fpeedily revived, than one would have fufpected. Now the air, in which the mouse liv'd all this while, had been clogg'd, and infected, with the excrementious effluvia of his body; for 'twas the fame all along; we having, purposely, forborn to take off the bladder, whofe regular diftenfions, and fhrinkings, fufficiently manifefted, that the veffel, whereof 'twas a part, did not leak. 120. We took a moufe, of an ordinary fize, and, having convey'd him into an oval glafs, fitted with a fomewhat long, and confiderably broad neck, that it might be wide enough to admit a moufe, in fpight of his ftruggling; we convey'd in, after him, a mercurial gage, in which we had carefully obferv'd, and mark'd the ftation of the mercury; and which was fo faften'd to a wire, reaching to the bottom of the oval glass, that the gage, remaining in the neck, was not in danger of being broken by the motions of the mouse in the oval part. The upper part of the long neck of the glafs was, notwithstanding the widenefs of it, hermetically feal'd, by means of a lamp, and a pair of bellows, that we might be fure the imprifon'd animal fhould breathe no other air, than what fill'd the receiver, at the time when it was feal'd. This done, the mouse was watched, |