he, by degrees, within about a quarter of an hour, recover'd. We after- PNEUMATICE wards, fent for another, kitten'd at the fame time; and inclofing that, alfo, in the receiver, obferv'd the violent convulfions, and, as it were, gafping for breath, into which he began to fall, at the fecond or third fuck, ended in a feeming death, within about a minute and a half. But, caufing the pump to be ply'd, the kitling gave manifeft figns of life, after he had endured feveral convulfions, as great as thofe of the firft fit, if not greater. When feven minutes, from the beginning of the exhauftion, were compleated, we let in the air; upon which, the little creature, that feem'd stark dead before, made us fufpect he might recover: but, tho' we took him out of the receiver, and put Aqua Vite into his mouth, yet he, irrecoverably, died in our hands.

86. To determine the quantity of air harbour'd in the pores of fluids, Experiments feems as difficult as it would be ufeful. To fhew how little the air, con- upon the air ujually bartain'd in water, would appear to leffen the bulk of the water, if it were bour'd in the fuffer'd to fly away in an open tube; we let it escape, in an exhausted re- pores of waceiver, without any artifice to catch it in which trial, the water did not ter, &c. part with any thing of its bulk,, that made a diminution fenfible to the eye. We, therefore, endeavour'd to make this lofs vifible, by fome other experiments.

A glafs-tube, feal'd at one end, and about thirty-fix inches in length, being fill'd with water, and inverted into a glafs-veffel, not two inches in diameter, and but a quarter of an inch, or little more, in depth; the glaffes were convey'd into a fit receiver, and the air leisurely pump'd out, and fomewhat flowly re-admitted; when, the numerous bubbles, that had afcended, during the operation, conftituted, at the top, an aerial aggregate, amounting to, wanting about an hundredth part of an inch.

87. Presently after, another tube was fill'd with the fame water, and inverted; when, the water, being drawn down to the furface of that in the veffel, and the air let in again, the water was impell'd up to the very top, within a tenth, and half a tenth of an inch.

The latter tube was forty-three inches and a half above the furface of the stagnant water; the air, collected out of the bubbles, at the top of the water, was, the first time, above three quarters of an inch; and the fecond time we estimated it, at one half, and one fixteenth. The first time, the water, in the pipe, was made to fubfide full as low as the furface of the ftagnant water; the fecond time, the lowest that we made it fubfide, feem'd to be four or five inches above the furface of the water in the open veffel.

But the air, at the top of the tube, poffefs'd more room than its bulk abfolutely required; because it was fomewhat defended from the preffure of the atmosphere, by the weight of the fubjacent cylinder of water, which perhaps, was about three or four feet long.

88. We provided a clear round glafs, furnish'd with a pipe, or ftem, about nine inches in length; the globular part of the glafs being, on the outfide, about three inches and a half in diameter: the pipe of this glass

Y y y 2

was,

PNEUMATICS was, within an inch of the top, melted at the flame of a lamp, and drawn out, for two or three inches, as fiender as a crow's quill, that the decreafe of the water, upon the recefs of the air, harbour'd in its pores, might be the more eafily obferv'd, and eftimated. Above this flender of the pipe, the glafs was, nearly, of the fame fize with the reft of the pipe; that the aerial bubbles, afcending thro' the flender part, might there find room to break, and fo prevent the lofs of any part of the water.

part

This veffel being filled, till the liquor reach'd to the top of the lender part; where, not being uniformly enough drawn out, it was fomewhat broader than elsewhere; we convey'd the glafs, together with a pedestal for it to rest upon, into a tall receiver; and, pumping out the air, there difclofed themselves numerous bubbles, afcending nimbly to the upper part of the glafs, where they made a kind of froth: but, by reafon of the figure of the veffel, they broke at the top of the flender part, and so never came to overflow.

This done, the pump was fuffer'd to reft a while, to give the aerial particles, lodg'd in the water, time to feparate them felves, and emerge; when, the pump was ply'd again. Thefe viciffitudes of pumping, and refting, lafted for a confiderable time; till, at length, the bubbles began to be very rare; foon after which, the external air was let into the receiver; when, it appear'd fomewhat ftrange, that notwithstanding fo great a multitude of bubbles as had efcaped out of the water, I could not, by attentively comparing the place where the furface of the water refted at first, (to which a mark had been affix'd) with that where it now ftood, difcern the difference to amount to above an hair's breadth; and the chief operator in the experiment profefs'd he could perceive no difference at all.

89. Filling a glafs of the fame fhape, and much of the fame bigness as the former, with claret-wine, and placing it upon a convenient pedestal, in a tall receiver, we caus'd fome of the air to be pump'd out; whereupon there emerged thro' the flender pipe, so very great a multitude of bubbles darted, as it were, upwards, as both pleas'd and furpriz'd us; but forc'd us to go warily to work, for fear the glafs fhould break, or the wine overflow; wherefore, we, feasonably, left off pumping, before the receiver was near exhaufted, and fuffer'd the bubbles to get away as they could, till the danger was paft; then, from time to time, we pump'd a little more air out of the receiver; the withdrawing a moderate quantity of air at a time fufficing, even at the latter end, to make the bubbles copioufly and fwiftly afcend, for above a quarter of an hour together.

The little inftrument made ufe of in thefe experiments, being defign'd to examine, among other things, the quantity of bubbles lurking in feveral liquors, may be apply'd to fpirit of wine, and chymical oils. And fome circumftances of our trials made us think, that it might be worth examining, what kind of fubftance may be obtain❜d by this treating aerial and fpirituous corpufcles.

way of

90. An oyster, being put into a very small receiver, and kept there long PNEUMATICS enough, to have, fucceffively, kill'd three or four birds, or beafts, &c. was Shell-fish in not thereby kill'd, nor, for ought we could perceive, confiderably di- an exhaufted fturb'd; only at each fuck we perceiv'd, that the air, contain'd between receiver. the two fhells, broke out at their commiffure; as we concluded from the foam which, at thofe times, came out all around that commiffure. About twenty-four hours after, I found, that both this oyfter, and another, that had been put, at the fame time, into the receiver, were alive.

On the fame day we put a pretty large craw-fifh into a large receiver, and found, that tho' he had been before injur'd by a fall, yet he feem'd not to be much incommoded, by being included, till the air was, in great measure, pump'd out; and then his former motion presently ceas'd, and he lay as dead, till, upon letting in a little air, he foon began to move afresh; and, upon withdrawing the air again, he presently, as before, became movelefs. Having repeated the experiment two or three times, we took him out of the receiver, when he appear'd not to have fuffer'd any harm.

91. Having put an oyfter into a vial, full of water, before we included it in the receiver, that thro' the liquor the motion of the bubbles, expected from the fish, might be the better feen, and confider'd; this oyfter prov'd fo strong, as to keep itfelf clofe fhut, and reprefs'd the eruption. of the bubbles, that, in the other, forc'd open the fhells, from time to time; and kept in its own air, as long as we had occafion to continue the trial.

92. A craw-fifh, that was thought more vigorous, being fubftituted in the place of the former craw-fifh, tho' once he feem'd to lose his motion: together with the air; yet, afterwards, he continu'd moving in the receiver, in fpight of our pumping.

receiver.

93.We took a receiver, fhaped almoft like a bolt-head, containing near Afcale-fi in a pint; and the globular part of it, being almost half full of water, we an exhausted put into it, at the orifice, a fmall gudgeon, about three inches long; which when it was in the water fwam nimbly up and down therein: then, having drawn out the air, fo that about nineteen parts out of twenty, or more, were exhausted; we fecur'd the return of the air from injuring our experiment.

Now the neck of the glafs, being very long, tho' there appear'd numerous bubbles all about the fifh; yet the reft of the water, notwithftanding the withdrawing of fo much air, emitted no froth, and but few bubbles.

The fish, both at his mouth and gills, for a long time, difcharg'd fuch a quantity of bubbles, as appear'd ftrange; and for about half an hour, when ever he rested a while, new bubbles would adhere to many parts of his body, (as if they were generated there) efpecially about the fins and tail; fo that he would appear almost befet with bubbles; and if, being excited to fwim, he was made to shake them off, he would quickly, upon a little reft, be befet with new ones, as before.

Almoft

PNEUMATICS

receiver.

Almoft all the while, he would gape, and move his gills, as before he was included; tho', towards the end of the time I watch'd him, he often neither took in, nor emitted any aerial particles that I could perceive.

After a while, he lay almost constantly with his belly upwards; and yet, would, in that pofture, swim brifkly as before. Nay, foon after, he feem'd to be more lively than at first putting in.

In about an hour and a half after he had been feal'd up, I found him almoft free from bubbles, with his belly upwards, and feeming fomewhat tumid, yet lively as before. But, an hour and a quarter after that, he feem'd to be movelefs, and fomewhat ftiff; yet, upon fhaking the glafs, obferving faint figns of life in him, by fome languid motions he attempted to make, when excited; I open'd the receiver, under water, to try if that liquor, and air, would recover him; when, the external water rufhing in, till it had fill'd the vacant part of the ball, and the greatest part of the stem, the fish funk to the bottom of it, with a greater appearance than ever of being alive: in which state, after he had continu'd a pretty while, I, by the help of the water he swam in, got him thro' the pipe, into a bafon of water, where he gave more manifeft figns of life. But, yet, for fome hours, he lay on one fide or other, without being able to swim, or rest on his belly, which appear'd very much shrunk in.

All the while he continu'd in the bafon of water, tho' he mov'd his gills, as before he had been feal'd up; yet I could not perceive, that he did, even in his new water, emit, as formerly, any bubbles; tho', two or three times, I held him by the tail in the air, and put him into the water again; where, at length, he grew able to lie conftantly upon his belly; tho' that retain'd much of its former lanknefs. And he lived, in the bafon, eight or ten days longer; tho' feveral gudgeons, fince taken, died there in a much lefs time.

Two animals, 94. Sept. 12. A fmall bird, having the abdomen open'd almoft from with large flank to flank, without injuring the guts, was put into a little receiver, wounds in their abdomen, in- and the pump being fet a-work, continued, for fome little time, without cluded in the giving any figns of distress; but at the end of about a minute and an half pneumatical from the beginning, fhe began to have convulfive motions in the wings and, tho' the convulfions were not univerfal, or appeared violent, as is ufual in other birds when the air is withdrawn, yet, at the end of two full minutes, letting in the air, and then taking off the receiver, we found the bird irrecoverable, tho' there appear'd no notable alteration in the lungs ; and the heart, or, at least, the auricles of it, continued beating for a while after.

95. We took, alfo, on the fame day, a pretty large frog, and having, without violating the lungs, or the guts, made two fuch incifions in the abdomen, that the two curl'd bladders, or lobes of the lungs, came out, almost totally, at them; we fufpended the frog, by the legs, in a fmall receiver, and, after we had pump'd out a large part of the air, the animal ftruggled very much, and feem'd to be much diforder'd; and when the receiver was well exhaufted, fhe lay ftill, for a while, as if she had been

dead; the abdomen and thigh being very much swell'd, as if fome rarify'dPNEUMATICS air, or vapour, forcibly diftended them. But as, when the frog was put in, one of the lobes was almoft full, and the other almost shrunk up; fo they continu'd to appear, after the receiver had been exhausted: but upon letting in the air, not only the body ceas'd to be tumid, but the plump bladder appear'd, for a while, fhrunk up as the other; and the receiver being remov'd, the frog presently revived, and quickly began to fill the lobe again with air.

96. The heart of an eel being taken out, and laid upon a plate of tin, The motion of in a small receiver; when we perceiv'd it to beat there, as it had done in the feparated the open air, we exhaufted the veffel, and faw, that tho' the heart grew animal in the heart of a cold very tumid, and, here and there, fent out little bubbles, yet it con-exhausted retinued to beat as manifeftly as before, and feemed to do fo more fwift-ceiver. ly; as we tried by counting the pulfations it made in a minute, whilft it was in the exhausted receiver, and when we had re-admitted the air, and alfo, when we took it out of the glass, and fuffer'd it to continue its motion in the open air. The heart of another eel, being, likewife, taken out, continu'd to beat in the empty'd receiver, as the other had done.

of

97. The heart of another eel, after having been included in an exhausted receiver, and then accurately fecured from leaking, tho' it appear'd very tumid, continu'd to beat there an hour; after which, finding its motion very languid, and almost ceas'd; by breathing a little upon that part the glafs where the heart was, it quickly regain'd motion, which I obferv'd a while; and, an hour after, finding it almoft quite gone, I was able to renew it, by the application of a little more warmth. At the end of the third hour, a bubble, that appear'd to be placed between the auricle and the heart, feem'd to have, now and then, a little trembling motion; but it was fo faint, that I could no more, by warmth, excite it, fo as plainly to perceive the heart to move: wherefore, I fuffer'd the outward air to rufh in, but could not difcern, that, thereby, the heart regain'd any fenfible motion, tho' affifted with the warmth of my breath and hands.

98. Sept. 10. A green-finch, having his legs and wings tied to a weight, The times was gently let down into a glafs body fill'd with water; the time of his wherein anitotal immerfion being mark'd. At the end of half a minute after that time, mals may be the strugglings of the bird feeming finish'd, when being fuddenly drawn up again, he was found quite dead.

kill'd by drow ning, or with. drawing of the

A fparrow, very lufty and quarrelfome, was tied to the fame air, compared. weight, and let down after the fame manner; but tho' he feem'd to be more vigorous under water than the other bird, and continued ftruggling almoft to the end of half a minute, from the time of his total immerfion; (during which, there afcended, from time to time, large bubbles from his mouth) yet, being drawn up as foon as ever the half minute was compleated, we found him, to our wonder, irrecoverably gone.

99. A fmall moufe, being held under water by the tail, emitted, from time to time, feveral aeriel bubbles out of his mouth; and, at laft, as a fpectator affirm'd, at one of his eyes: being taken out, at the end of half a mi

nute,,