New experiments physico-mechanicall, touching the spring of the air, and its effects (made, for the most part, in a new pneumatical engine) : written by way of letter to the Right Honorable Charles, Lord Vicount of Dungarvan, eldest son to the Earl of Corke / by the Honorable Robert Boyle, Esq.

A Digression containing some Doubts touching Respi∣ration.

I Fear Your Lordship will now expect, that to these Experiments I should add my Reflections on them, and attempt, by their assistance, to resolve the Diffi∣culties that occur about Respiration; since at the beginning I acknowledg'd a further Enquiry into the Nature of that, to have been my Design in the related Tryals. But I have yet, because of the inconve∣nient Season of the Year, made so few Experiments, and have been so little sa∣tisfied by those I have been able to make, that they have hitherto made Respiration appear to me rather a more, then a less Mysterious thing, then it did before. But yet, since they have furnish'd me with some such new Considerations, concern∣ing the use of the Air, as confirms me in my Diffidence of the Truth of what is commonly believ'd touching that matter; That I may not appear sullen or lazy, I am content not to decline employing a

few hours in setting down my Doubts, i•• presenting Your Lordship some Hints, and in considering whether the Tryals made in our Engine, will at least assist us to discover wherein the Deficiency lies that needs to be supply'd.

And this, My Lord, being all my pre∣sent Design, I suppose You will not ex∣pect that (as if You knew not, or had for∣gotten what Anatomists are wont to teach) I should entertain You with a need∣less Discourse of the Organs of Respira∣tion, and the variety of their Structure in several Animals; though if it were ne∣cessary, and had not been perform'd by o∣thers, I should think, with Galen, that by treating of the Fabricks of living Bodies, I might compose Hymns to the wise Au∣thor of Nature, who, in the excellent con∣trivance of the Lungs, and other parts of (those admirable Engines) Animals, ma∣nifests himself to be indeed what the Elo∣quent Prophet most justly speaks him, Wonderful in Councel, and excellent in working.

Nor shall we any further meddle with those Controversies so much agitated a∣mong the Moderns, namely, Whether the motion of the Lungs in Respiration be their

own, or but consequent to the motion of the Thorax, Diaphragme, and (as some Learn∣ed Men would have it) the Abdomen; And, Whence it is that the Air swells the Lungs in Inspiration, any further then they may receive light from our Engine: But that it may appear what kinde of service it is that may be expected from it on this oc∣casion, we must premise a few Words to shew wherein the strength of the Obje∣ction we are to answer, lies: In favor then of those that would have the Lungs ra∣ther passive then active in the business of Respiration, it may against the common opinion be alledg'd, That as the Lungs be∣ing destitute of Muscles and of Fibres, are unfit to dilate themselves, so it ap∣pears, that without the motion of the Thorax they would not be fill'd with Air. Since as our Learned Friend Dr. High∣more has well (and congruously, to what our selves have purposely try'd) ob∣serv'd, if a live Dog have a great wound made in his Chest, the Lobes of the Lungs on that side of the Mediasti∣••um will subside and lie still; the Tho∣rax and the Lobes on the other side of the Mediastinum, continuing their former motion. And if suddenly at once

the Muscles of the Chest be on both sides dissected, upon the Ingress of the Air, the whole Lungs, though untouch'd, will remain moveless, at least, as to any ex∣pansion or contraction of their substance.

To which we may adde the Observati∣on of the diligent Bartholinus, who af∣firms the like of the Diaphragme al∣so, namely, That it being wounded, the Lungs will fall together, and the Respi∣ration cease, which my Experiments op∣pose not, provided the Wound be any thing great. And indeed the Diaphragme seems the principal Instrument of ordina∣ry and gentle Respiration, although to restrain'd Respiration (if I may so call it) the intercostal Muscles, and perhaps some others may be allowed eminently to concur. But the chief of the Contro∣versies formerly pointed at, is not yet de∣cided, namely, what it is that conveys the Air into the Lungs. For when, to coun∣terballance all that has been alledg'd, those that plead for the Lungs, demand what it is that should bring the Air into the Lungs, if themselves do not attract it, their Antagonists disagree about the Re∣ply. For when to this question some of the best Modern Philosophers answer,

that by the dilatation of the Chest the contiguous Air is thrust away, and that pressing upon the next Air to it, and so onwards, the Propulsion is continued till the Air be driven into the Lungs, and so dilate them: When this (I say) is an∣swered, it is Objected even by Bartholine himself, as a convincing Reply, that, ac∣cording to this Doctrine, a Man could not fetch his Breath from a great Vessel full of Air, with a slender Neck, because, that when his Mouth covers the Orifice of the Neck, the dilatation of his Thorax could not propell the Air in the Vessel into his Lungs, by reason of its being separated by the inclosing Vessel from the ••mbient Air; and yet, say they, Experience wit∣nesses that out of such a Vessel a Man may suck Air. But of this difficulty our Engine furnishes us with an easie Solution, since many of the former Experiments have ma∣nifested, That in the case proposed, there needs not be made any (though 'tis true that in ordinary Respiration there is wont to be made some) propulsion of the Air by the swelling Thorax or Abdomen into the Lungs; since upon the bare Dilatation of the Thorax, the Spring of that internal Air, or halituous substance that is wont

to possess as much of the Cavity of the Chest as the Lungs fill not up, being much weaken'd, the external and contiguous Air must necessarily press in at the open Winde-Pipe into the Lungs, as finding there less resistance then any where else a∣bout it.

And hence (by the way) we may derive a new assistance to judge of that famous Controversie disputed among Naturalists and Physicians, ever since Galens time, some maintaining that the Chest, with the contained Lungs, may be resembled to a pair of Bellows, which comes therefore to be fill'd because it was dilated: And o∣thers pleading to have the comparison made to a Bladder, which is therefore di∣lated because it is fill'd. For as to the Thorax, it seems evident from what has been lately said, that it, like a pair of Bel∣lows, happens to be partly fill'd with Air, but because it was dilated: But as for the Lungs themselves, who want Fibres to distend them, they may fitly enough be compar'd to a Bladder; since they are di∣lated by being fill'd namely, by that Air which rushes into them upon the dilatation of the Chest, in whose increased Cavity it findes (as we freshly noted) less resist∣ance

to its Spring then elsewhere. And this brings into my minde that strange Observation of Nicolaus Fontanus, a Phy∣sitian at Amsterdam, who testifies, That in a Boy of the same Town, four years old, there was found, instead of Lungs, a certain Membranous Bladder; which be∣ing fill'd with Wind, and furnish'd with little Veins, had its origination from the Wind-Pipe it self; which being suppos'd true, how well it will agree with most of the Opinions touching Respiration, I leave to be considered.

And thus may the grand Objection of Bartholine, and others, be answered: But I leave to Anatomists to consider what is to be said to some Observations that seem to contradict those Anatomical Experi∣ments already mention'd: Such was par∣ticularly that which I remember I have read in Sennertus (from the observation of his Farther-in-law Schato) of a Melancho∣ly Student, who having stabb'd himself, and pierced the Diaphragme in the thinner or tendonous part (call'd by many the Nervous Circle) lived seven Moneths af∣ter he had so wounded himself, though af∣ter his death (preceded by violent Vomit∣ings)

the Wound (perchance dilated by those strainings) appear'd so great, that the whole Stomack was found to have got in by it into the left side of the Thorax. And such also was the accident that hap∣pen'd to a Noble Man, whom I remem∣ber I have seen, and who is yet alive, in whose Chest there has, for these many years, remain'd a hole so great, that the motion of his Heart may be perceiv'd by it. These (I say) and some other Obser∣vations, I shall now forbear to insist on, because I hold it not unfit, before we come to consider the use of Respiration, that we acquaint Your Lordship with an Ingenious Conjecture, that was made at the cause of the hasty death of the Ani∣mals our Engine kill'd: namely, That it was not the want of Air that destroy'd them, but the Pressure of the innate Air in the cavity of the Chest; as if the Spring of this Air being no longer coun∣terballanc'd by the ambient Air, was there∣by become so strong, that it kept the Thorax forcibly distended, and hinder'd its wonted contraction; and so compress'd the Lungs and their Vessels, as to obstruct the Circulation of the Blood. And this

Conjecture, as it is specious enough, so I might have admitted it for true, but that I consider'd, that (not to mention that one, especially of the Animals kill'd in our Engine, seem'd manifestly for a pret∣ty while, and not long before he dy'd, to move his Thorax, as if he exercis'd Respi∣ration) the diligent Wallaeus relates, That he divers times observ'd, in the Dissecti∣on of live Bodies, that the Membrane that invests the Lungs, had Pores in it as big as the larger sort of Peas, which a∣grees with the Observations of Chyrur∣gions and Physitians, viz. That matter collected in the Thorax, has penetrated in∣to the Lungs, and been discharged by coughing. And I remember too, that most of the Animals we kill'd in our Engine were Birds, of whose Lungs Harvey somewhere informs us, That he ob∣serv'd them very manifestly to open at their Extremities into the Abdomen. And by such Perforations we may well suppose the passage free betwixt the exter∣nal Air and that in the Abdomen: But 〈◊〉〈◊〉Conjecture may be further 〈◊〉〈◊〉Besides, to show that the Anim•••••• 〈◊〉〈◊〉died in our Glasses, need not be 〈◊〉〈◊〉

to have been kill'd by the want of Air, we foresee another Argument that we must deal so ingeniously with Your Lordship, as not to conceal. You very well know, that besides the generality of the Schools, there are many new Philosophers who, though they dissent from the old Peripateticks in other things, do, as they, deny the possibility of a Vacuum; and hold, that those spaces which are devoid of Air, and other grosser Bodies, are all of them exactly replenished with a certain Etherial Matter, so thin and subtle, that it can freely permeate the Pores of the compactedst and closest Bodies, and ev'n of Glass it self. Now some of those Na∣turalists that are of this perswasion may object, That the Animals that died in our Receivers, did so, not so much for lack of Air, as by reason that the Air that was pump'd out was necessarily succeeded by an Etherial Substance; which consisting of parts vehemently agitated, and so very small, as without resistance to pass in and out through the very Pores of Glass; it may well be suppos'd, that a considerable quantity of this restless and subtle Mat∣ter, meeting together in the Receiver,

with the excessive heat of it, may be quickly able to destroy a little Animal, or at least, make the Air too intemperately hot to be fit for Respiration.

But though this be a Difficulty not so easily to be resolv'd without the assistance of our Engine, yet I suppose we have al∣ready answer'd the Objection by our 38^th and 39^th Experiments; which though we made partly for other purposes, yet we premis'd them onely to clear up the diffi∣culty propos'd.

Another suspition we should have en∣tertain'd concerning the death of our Ani∣mals, namely, That upon the sudden re∣moval of the wonted pressure of the am∣bient Air, the warm Blood of those Ani∣mals was brought to an Effervescence or Ebullition, or at least so vehemently ex∣panded, as to disturb the Circulation of the Blood, and so disorder the whole Oe∣conomy of the Body. (This (I say) I should have had some suspition of) but that Animals of a hot Constitution are not the sole ones that cannot in our ex∣hausted Engine exercise the Function of Life. But I must not now dwell upon matters of this nature, because I think it high time to proceed to the considerati∣on

of the principal subject of our Engine, namely, The use of Respiration; or ra∣ther, The use of the Air in Respiration. For whereas of the divers uses of it men∣tion'd by Anatomists the most, such as the Production and Modulation of the Voice by the Elision of the Air, the La∣rynx &c. the expulsion of Excrements by Coughing, the conveying in of Odours by Inspiration, and some others, rather convenient for the well being of an Ani∣mal, then absolutely necessary to his Life: Whereas (I say) the other uses are such as we have said, The great Hippocrates him∣self gives this notable Testimony to the use of the Air, as to Animals endow'd with Lungs, Mortalibus (says he) hic (spi∣ritus) tum vitae, tum morborum aegrotis cau∣sa est. Tantáque corporibus omnibus spi∣ritûs inest necessitas, ut siquidem aliis om∣nibus & cibis & potionibus, quis abstineat, duos tamē aut tres, vel plures dies possit vi∣tam ducere: At si quis spiritus in corpus vias intercipiat, vel exiguâ diei parte, ho∣mini pereundum sit; Ad••o necessarius est usus spiritûs in corpore. Ad haec quo{que}, quum omnibus aliis actionibus homines qu••∣escant, quod mutationibus innumeris vita sit exposita, ab hâc tamen solá actione nun∣quam

desistant animantia, quin aut spiritum adducant, aut reddant.

But touching the account upon which the Inspiration and Exspiration of Air (both which are comprehended in 〈 in non-Latin alphabet 〉〈 in non-Latin alphabet 〉 Respiration) is so necessary to Life, both Naturalists and Physitians do so disagree, that it will be very difficult either to re∣concile their Opinions, or determine their Controversies.

For first, Many there are who think the chief (if not sole) use of Respiration to be the Cooling and tempering of that Heat in the Heart and Blood, which other∣wise would be immoderate: And this O∣pinion, not onely seems to be most recei∣ved amongst Scholastick Writers, but di∣vers of the new Philosophers, Cartesians, and others, admitted with some variation; teaching, That the Air is necessary, by its coldness, to condense the Blood that pas∣ses out of the right Ventricle of the Heart into the Lungs, that thereby it may obtain such a consistence, as is requisite to make it fit Fewel for the vital Fire or Flame, in the left Ventricle of the heart. And this Opinion seems favor'd by this, That Fishes, and other cold Creatures, whose Hearts have but one cavity, are al∣so

unprovided of Lungs, and by some o∣ther considerations. But though it need not be deny'd, that the inspir'd Air may sometimes be of use by refrigerating the Heart; yet (against the Opinion that makes this Refrigeration, the most genuine and constant use of the Air) it may be Obje∣cted, That divers cold Creatures (some of which, as particularly Frogs, live in the Water) have yet need of Respiration, which seems not likely to be needed for Refrigeration by them that are destitute of any sensible heat, and besides, live in the cold Water: That even decrepid old Men, whose natural heat is made very languid, and almost extinguish'd by rea∣son of age, have yet a necessity of fre∣quent Respiration: That a temperate Air is fittest for the generality of breathing Creatures; and as an Air too hot, so al∣so an Air too cold, may be inconvenient for them (especially, if they be troubled with an immoderate degree of the same Quality which is predominant in the Air:) That in some Diseases the natural heat is so weaken'd, that in case the use of Respi∣ration were to cool, it would be more hurtful then beneficial to breath; and the suspending of the Respiration, may sup∣ply

the place of those very hot Medicines that are wont to be employ'd in such Di∣stempers: That Nature might much bet∣ter have given the Heart but a moderate heat, then such an excessive one, as needs to be perpetually cool'd, to keep it from growing destructive; which the gentle, and not the burning heat of an Animals Heart, seems not intense enough so indi∣spensably to require. These, and other Objections, might be oppos'd, and press'd against the recited Opinion: But we shall not insist on them, but onely adde to them, That it appears not by our fore∣going Experiments (I mean the 38^th and 39^th) that in our exhausted Receiver, where yet Animals die so suddenly for want of Respiration, the ambient Body is sensibly hotter then the common Air.

Other Learned Men there are, who will have the very substance of the Air to get in by the Vessels of the Lungs, to the left Ventricle of the Heart, not onely to temper its heat, but to provide for the generation of Spirits. And these alledge for themselves the Authority of the An∣tients, among whom Hippocrates seems manifestly to favor their Opinion; and both Aristotle and Galen do sometimes

(for methinks they speak doubtfully e∣nough) appear inclinable to it. But for ought ever I could see in Dissections, it is very difficult to make out, how the Air is convey'd into the left Ventricle of the Heart, especially the Systole and Diastole of the Heart and Lungs, being very far from being Synchronical: Besides, that the Spirits seeming to be but the most subtle and unctuous Particles of the Blood, appear to be of a very differing Nature from that of the lean and incom∣bustible Corpuscles of Air. Other Ob∣jections against this Opinion have been propos'd, and prest by that excellent Ana∣tomist, and my Industrious Friend, Dr. Highmore, to whom I shall therefore refer you.

Another Opinion there is touching Re∣spiration, which makes the genuine use of it to be Ventilation (not of the Heart, but) of the Blood, in its passage thorow the Lungs; in which passage, it is dis∣burthened of those Excrementitious Steams, proceeding, for the most part, from the superfluous Serosities of the Blood, (we may adde) and of the Chyle too, which (by those new Conduits of late very happily detected by the famous

Pecquet) hath been newly mix'd with it in the Heart.) And this Opinion is that of the Industrious Moebius, and is said to have been that of that excellent Philoso∣pher Gassendus; and hath been in part an Opinion almost vulgar: But this Hypo∣thesis may be explicated two ways: For first, The necessity of the Air in Respi∣ration, may be suppos'd to proceed from hence; That as a Flame cannot long burn in a narrow and close place, because the Fuliginous Steams it uncessantly throws out, cannot be long receiv'd into the am∣bient Body; which after a while growing too full of them, to admit any more, sti∣fles the flame, so that the vital Fire in the Heart requires an ambient Body, of a yielding nature, to receive into it the su∣perfluous Serosities and other Recrements of the Blood, whose seasonable Expulsi∣on is requisite to depurate the Mass of Blood, and make it fit both to Circulate, and to maintain the vital heat residing in the Heart. The other way of explicating the above mention'd Hypothesis, is, by supposing, that the Air does not onely, as a Receptacle, admit into its Pores the Ex∣crementitious vapors of the Blood, when they are expell'd through the Wind-Pipe,

but does also convey them out of the Lungs, in regard that the inspired Air, reaching to all the ends of the Aspera Ar∣teria, does there associate it self with the Exhalations of the circulating Blood, and when 'tis exploded, carrys them away with it self, as we see that winds speedily dry up the surfaces of wet Bodies, not to say any thing of what we formerly observd touch∣ing our Liquor, whose fumes were strange∣ly elevated upon the Ingress of the Air.

Now of these two ways of explicating the use of Respiration, our Engine af∣fords us this Objection against the first; That upon the Exsuction of the Air, the Animals die a great deal sooner then if it were left in the Vessel; though by that Exsuction the ambient space is left much more free to receive the steams that are ei∣ther breathed out of the Lungs of the Animal, or discharg'd by insensible Tran∣spiration through the Pores of his Skin.

But if the Hypothesis propos'd, be taken in the other sense, it seems congruous e∣nough to that grand observation, which partly the Phaenomena of our Engine, and partly the relations of Travellers, have suggested to us, namely, That there is a

certain consistence of Air requisite to Re∣spiration; so that if it be too thick, and already over-charged with vapors, it will be unfit to unite with, and carry off those of the Blood, as Water will dissolve, and associate to it self but a certain proportion of saline Corpuscles; and if it be too thin or rarefied, the number or size of the Aërial Particles is too small to be able to assume and carry off the halituous Excre∣ments of the Blood, in such plenty as is requisite.

Now that Air too much thicken'd (and as it were clogg'd) with Steams, is unfit for Respiration, may appear by what is wont to happen in the Lead-Mines of De∣vonshire, (and, for ought I know, in those too of other Countrys, though I have seen Mines where no such thing was com∣plain'd of) for I have been inform'd by more then one credible Person (and parti∣cularly by an Ingenious Man, that has of∣ten, for curiosity, digg'd in those Mines, and been imploy'd about them) that there often rises Damps, as retaining the Ger∣mane Word by which they call them) which does so thicken the Air, that unless the Work-men speedily make signs to them that are above, they would (which

also sometimes happens) be presently stifled for want of Breath; and though their Companions do make haste to draw them up, yet frequently, by that time they come to the free Air, they are, as it were, in a swoon, and are a good while be∣fore they come to themselves again. And that this swooning seems not to proceed from any Arsenical or Poysonous Exhala∣tion contain'd in the Damp; as from its over-much condensing the Air, seems pro∣bable from hence; That the same Damps oftentimes leisurely extinguish the flames of their Candles or Lamps; and from hence also that it appears (by many Rela∣tions of Authentical Authors) that in those Cellars where great store of new Wine is set to work, men have been suffo∣cated by the too great plenty of the steams exhaling from the Must, and too much thickning the Air: as may be gathered from the custom that is now used in some hot Countrys, where those that have oc∣casion to go into such Cellars, carry with them a quantity of well kindled Coals, which they hold near their Faces; where∣by it comes to pass, that the Fire discus∣sing the Fumes, and rarefying the Air re∣duces the ambient Body to a consistence fit for Respiration.

We will adde (by way of confirmati∣on) the following Experiment: In such a small Receiver, as those wherein we kill'd divers Birds, we carefully clos'd up one, who, though for a quarter of an hour he seem'd not much prejudiced by the close∣ness of his Prison, afterwards began first to pant very vehemently, and keep his Bill very open, and then to appear very sick; and last of all, after some long and violent strainings, to cast up some little matter out of his Stomack: which he did several times, till growing so sick, that he stag∣ger'd and gasp'd, as being just ready to die; we perceiv'd, that within about three quarters of an hour from the time that he was put in, he had so thickned and tainted the Air with the Steams of his Body, that it was become altogether unfit for the use of Respiration: Which he will not much wonder at, who has taken notice in Sanctorius his Statica Medicina, how much that part of our Aliments, which goes off by insensible Transpiration, ex∣ceeds in weight all the visible and grosser Excrements both solid and liquid.

That (on the other side) an Air too much dilated is not serviceable for the ends of

Respiration, the hasty death of the Ani∣mal we kill'd in our exhausted Receiver, seems sufficiently to manifest. And it may not irrationally be doubted, whether or no, if a Man were rais'd to the very top of the Atmosphere, he would be able to live many minutes, and would not quick∣ly dye for want of such Air as we are wont to breath here below. And that this Conjecture may not appear extrava∣gant, I shall on this occasion subjoyn a memorable Relation that I have met with in the Learned Iosephus Acosta, who tells us, That when he himself past the high Mountains of Peru, (which they call Pariaecaca) to which, he says, That the Alps themselves seem'd to them but as ordinary Houses, in regard of high Tow∣ers, he and his Companions were surpri∣sed with such extream Pangs of Straining and Vomiting, (not without casting up Blood too) and with so violent a Distem∣per, that he concludes he should undoubt∣edly have dyed, but that this lasted not a∣bove three or four hours, before they came into a more convenient and natural temperature of Air: To which our Learn∣ed Author addes an Inference, which be∣ing the principal thing I design'd in men∣tioning,

the Narrative I shall set down in his own Words: I therefore (says he) per∣swade myself, That the Element of the Air is there so subtle and delicate, as it is not proportionable with the breathing of Man, which requires a more gross and temperate Air; and I believe it is the cause that doth so much alter the Stomack, and trouble all the Disposition. Thus far our Author, whose Words I mention, that we may ghess by what happens somewhat near the Confines of the Atmosphere (though propably far from the surface of it) what would happen beyond the Atmosphere. That which some of those that treat of the height of Mountains, relate out of Ari∣stotle, namely, That those that ascend to the top of the Mountain Olympus, could not keep themselves alive, without car∣rying with them wet Spunges, by whose assistance they could respire in that Air, o∣therwise too thin for Respiration: (That Relation (I say) concerning this Moun∣tain) would much confirm what has been newly recited out of Acosta, if we had sufficient reason to believe it: But, I con∣fess, I am very diffident of the truth of it; partly because when I pass'd the Alps, I took notice of no notible change betwixt

the consistence of the Air at the top and at the bottom of the Mountain; partly because of a very punctual relation made by an English Gentleman, of his ascensi∣on on to the top of the Pike of Tenariff (which is by great odds higher then Olym∣pus) I finde no mention of any such dif∣ficulty of breathing; and partly also be∣cause the same Author tells us out of A∣ristotle, That upon the top of Olympus there is no motion of the Air, insomuch, that Letters traced upon the dust, have been, after many years, found legible, and not discompos'd; whereas that Inquisi∣tive Busbequius (who was Ambassador from the German to the Turkish Em∣peror) in one of his Eloquent Epistles, tells us, upon his own knowledge, That Olympus may be seen from Constantino∣ple, blanch'd with perpetual Snow; which seems to argue, That the top of that, as well as of divers other tall Hills, is not a∣bove that Region of the Air wherein Me∣teors are formed. Though otherwise, in that memorable Narrative which David Fraelichius, made of his ascent to the top of the prodigiously high Hungarian Mountain Carpathus: he tells us, That when, having pass'd through very thick

Clouds, he came to the very top of the Hill, he found the Air so calm and subtle, that not a hair of his head moved, whereas in the Lower Stages of the Mountain he felt a ve∣hement Wind. But this might well be casual, as was his, having a clear Air where he was, though there were Clouds, not onely beneath him, but above him.

But (though what has been hither∣to discours'd, incline us to look up∣on the Ventilation and Depuration of the Blood, as one of the principal and constant uses of Respiration; yet) methinks it may be suspected that the Air does something more then bare∣ly help to carry off what is thrown out of the Blood in its passage through the Lungs, from the right Ventricle of the Heart to the left. For we see, in Phlegmatick Constitutions and Dis∣eases, that the Blood will circulate to∣lerably well, notwithstanding its being excessively serous: And in Asthmatical Persons, we often see, that though the Lungs be very much stuff'd with tough Phlegm, yet the Patient may live some Moneths, if not some Years. So that

it seems scarce probable, that either the want of throwing out the superfluous Se∣rum of the Blood for a few Moments, or the detaining it, during so short a while, in the Lungs, should be able to kill a per∣fectly sound and lively Animal: I say, for a few moments, because, that having di∣vers times try'd the Experiment of killing Birds in a small Receiver, we commonly found, that within half a minute of an hour, or thereabouts, the Bird would be surpris'd by mortal Convulsions, and with∣in about a minute more would be stark dead, beyond the Recovery of the Air, though never so hastily let in. Which sort of Experiments seem so strange, that we were oblig'd to make it several times, which gain'd it the Advantage of having Persons of differing Qualities, Professi∣ons and Sexes, (as not onely Ladies and Lords, but Doctors and Mathematicians) to witness it. And to satisfie Your Lord∣ship, that it was not the narrowness of the Vessel, but the sudden Exsuction of the Air that dispatch'd these Creatures so soon; we will adde, That we once inclos'd one of these Birds in one of these small Receivers, where, for a while, he was so little sensible of his Imprisonment, that

he eat very chearfully certain Seeds that we convey'd in with him, and not onely liv'd ten minutes, but had probably liv'd much longer, had not a great Person, that was Spectator of some of these Experi∣ments, rescu'd him from the prosecution of the Tryal. Another Bird being with∣in about half a minute, cast into violent Convulsions, and reduc'd into a sprawling condition, upon the Exsuction of the Air, by the pitty of some Fair Lady's (related to Your Lordship) who made me hastily let in some Air at the Stop-cock, the gasping Animal was presently recover'd, and in a condition to enjoy the benefit of the Lady's Compassion. And another time also, being resolv'd not to be inter∣rupted in our Experiment, we did, at night, shut up a Bird in one of our small Recei∣vers, and observ'd, that for a good while he so little felt the alteration of the Air, that he fell asleep with his head under his wing; and though he afterwards awak'd sick, yet he continu'd upon his legs be∣tween forty minutes and three quarters of an hour; after which, seeming ready to expire, we took him out, and soon found him able to make use of the liberty we gave him for a compensation of his suffer∣ings.

If to the foregoing Instances of the sudden destruction of Animals, by the re∣moval of the ambient Air, we should now annex some, that we think fitter to re∣serve till anon; perhaps Your Lordship would suspect, with me, that there is some use of the Air, which we do not yet so well understand, that makes it so conti∣nually needful to the Life of Animals. Paracelsus indeed tells us, That as the Sto∣mack concocts Meat, and makes part of it useful to the Body, rejecting the other part, so the Lungs consume part of the Air, and proscribes the rest. So that according to our Hermetick Philosopher (as his follow∣ers would have him stil'd) it seems we may suppose, that there is in the Air a little vital Quintessence (if I may so call it) which serves to the refreshment and re∣stauration of our vital Spirits, for which use the grosser and incomparably greater part of the Air being unserviceable, it need not seem strange that an Animal stands in need of almost incessantly draw∣ing in fresh Air. But though this Opini∣on is not (as of some of the same Author) absur'd, yet besides that, it should not be barely asserted, but explicated and prov'd; and besides that, some Objections may be

fram'd against it, out of what has been al∣ready argu'd against the Transmutation of Air into vital Spirits: Besides these things, it seems not probable, that the bare want of the Generation of the won∣ted quantity of vital Spirits, for less then one minute, should within that time be able to kill a lively Animal, without the help of any external violence at all.

But yet, on occasion of this Opinion of Paracelsus, perhaps it will not be im∣pertinent, if before I proceed, I acquaint Your Lordship with a Conceit of that de∣servedly Famous Mechanician and Chy∣mist, Cornelius Drebell, who among o∣ther strange things that he perform'd, is affirm'd (by more then a few credible Per∣sons) to have contriv'd for the late Learn∣ed King Iames, a Vessel to go under Wa∣ter; of which, tryal was made in the Thames, with admired success, the Vessel carrying twelve Rowers, besides Passen∣gers; one of which is yet alive, and rela∣ted it to an excellent Mathematician that inform'd me of it. Now that for which I mention this Story, is, That having had the curiosity and opportunity to make particular Enquiries among the Relations of Drebell, and especially of an Ingenious Phy∣sitian

that marry'd his daughter, concer∣ning the grounds upon which he concei∣ved it feasible to make men unaccustom'd to continue so long under water without suffocation, or (as the lastly mention'd Person that went in the vessell affirmes) without inconvenience. I was answer'd, that Drebell conceiv'd, that 'tis not the whole body of the Air, but a certain Quin∣tessence (as Chymists speake) or spiritu∣ous part of it, that makes it fit for respira∣tion, which being spent, the remaining grosser body, or carcase (if I may so call it) of the Air, is unable to cherish the vi∣tall flame residing in the heart: So that (for ought I could gather) besides the Mechanicall contrivance of his vessell he had a Chymicall liquor, which he accoun∣ted the chiefe Secret of his submarine Na∣vigation. For when from time to time he perceiv'd, that the finer and purer part of the Air was consum'd, or over clogg'd by the respiration, and steames of those that went in his ship, he would, by unstopping a vessell full of this liquor, speedily restore to the troubled Air such a proportion of Vitall parts, as would make it againe, for a good while, fit for Respiration, whe∣ther by dissipating, or precipitating the

grosser Exhalations, or by some other in∣telligible way, I must not now stay to examine. Contenting my selfe to add, that having had the opportunity to do some service to those of his Relations, that were most Intimate with him, and having made it my business to learne what this strange Liquor might be, they constantly affirm'd that Drebell would never disclose the Liquor unto any, nor so much as tell the matter whereof he made it, to above one Person, who himselfe assur'd me that it was.

This account of Drebell's performance, I mention, not that I any further assent to his opinion then I have already intimated, but because the man, and the Invention being extraordinary, I suppose Your Lordship will not be displeas'd to know the utmost I could learne about it; especi∣ally not having found it mention'd by any Writer. Wherefore I have been some∣times inclin'd to favourable thoughts of their opinion, who would have the Aire necessary to ventilate, and cherish the vi∣tall flame, which they do suppose to be continually burning in the heart. For we see, that in our Engine the flame of a Lamp will last almost as little after the Exsucti∣on

on of the Air, as the life of an Animall: Nay I remember, that though I devis'd a more promising way, to make a fire last in our exhausted Receiver, yet it would not succeed: We tooke a hard body made in the forme of a Clove, but twice as long, and proportionably thick, this body be∣ing made of such a Composition, that if it be kindl'd at the upper end, it will most certainly burn away to the very bot∣tome, much better then a Match; we con∣vey'd it diverse times kindl'd at the upper end, into one of our small Receivers, but still found, that though presently upon the Exsuction of the Air, it would leave smoaking, and seeme quite gone out, and againe begin to smoke as soon as the Air was let in upon it; yet if the Air were kept out but foure or five minutes, the fire would be totally, and irrevocably ex∣tinguish'd. To which wee will adde, that though we convey'd into a great Re∣ceiver, a small lamp with rectifi'd spirit of Wine, that being so pure as not to smut the Cotton weeke, or so much as a piece of white Paper held over it; yet we could not by divers tryalls make the flame last a couple of minutes after the Air was begun to be drawne out. But though our Engine

thus shews us a new kind of resemblance betwixt fire and life: yet the opinion we have last mention'd is not free from Dif∣ficulties. For though in the hearts of ma∣ny Animall's Blood be a warm liquor, and in some ev'n a hot one; yet it is not easie to conceive either how the Air (in sub∣stance) can get thither, or how, in case it could, it were able to encrease the heat. Since, however, the Air may encrease the heat of a coale by blowing off the ashes, and making the active Corpuscles pierce further into the kindl'd body, and shatter it the more, yet we see hot liquors have their heat allay'd, and not augmented, by having Air blown on them. And whereas some Eminent Naturalists think it not in∣convenient, to make the heat residing in the heart to be a true flame, provided they adde, that 'tis such a temperate, and almost insensible fire, as the flame of spirit of Wine, which will long burne upon fine white Linnen or Paper without consu∣ming either: give mee leave to wish that they had been more curious to make diffe∣ring trials with that liquor. For (as we ob∣serve in another Treatise) the reason why a Linnen cloth, dipp'd in common Spirit of Wine, is not burnt by the flame of it, is

because the Phlegm of the Liquor de∣fends the Cloth. And the Flame of Spi∣rit of Wine is so far from being too weak to burn a piece of Paper, or of Linnen, that I have us'd it in Lamps to distill Li∣quors out of tall Cucurbits, and found that the Spirit burn'd away indeed much faster then Sallet Oyl, but gave at least as great a heat: Nay, I have, for curiosity sake, melted crude Gold, and that rea∣dily enough, with the bare Flame of pure Spirit of Wine.

But not to press this any further, we will, on this occasion, venture to subjoyn an odde Observation, which may perhaps invite to a further Enquiry into the Opi∣nion we have for Discourse sake oppos'd. Our English Democritus, Dr. Harvey, pro∣poses this difficult and noble Problem to Anatomists, Why a faetus, even out of the Womb, if involv'd in the secundines, may live a good while without a Respiration; but in case after having once begun to breath, its respiration be stopp••d, it will presently die. We are far from pretending to solve so hard a Problem, but this we try'd in re∣lation to it; We took a Bitch that was said to be almost ready to whelp, and ha∣ving caus'd her to be hang'd, we presently

open'd her Abdomen, and found four Pup∣peys in her Womb; one of these we took out, and having freed him from the Tegu∣ments th•••• involv'd him, and from the Liquor he swam in, we observ'd that he quickly open'd his Mouth very wide, mov'd his Tongue, and exercis'd Respi∣ration; then we open'd both his Abdomen and his Chest, and cut assunder the Dia∣phragme, notwithstanding which, he seem••d often to endeavor Respiring, and mov'd in a notable manner, both the In∣tercostal Muscles, part of the Diaphragme, the Mouth and the Tongue: But that which we mention this Puppy for, was this, That being desirous to try whether the other yong ones that had not yet breath'd at all, would long survive this or no; we took them also out of the Womb, and having open'd them, found none of them so much alive, as to have any perceptible motion in his heart, where∣as the heart of that Puppy which had once enjoy'd the benefit of Respiration, con∣tinu'd beating so long, that we our selves observ'd the Auricle to beat, after five or six hours; and a Servant that staid up and watch'd it after we were gone to Bed, af∣firm'd, That he saw the Pulsation conti∣nue

about two hours longer. I shall leave it to others to make Reflections upon this Observation, compar'd with Dr. Har∣vey's Problem.

It is much doubted, whether Fishes breath under Water, and we shall not take upon us, as yet, to determine the Questi∣on either way, because we have not yet been able to procure little Fishes alive to make Experiments upon: That such as are not Setaceous (for such manifestly breath) have not Respiration, properly so call'd, such as is exercis'd by four footed Beasts, and Birds, may be argu'd from their having but one cavity in their Hearts, & from their want of Lungs, whence they are observ'd to be Mute; unless we say, what is not altogether absurd, That their Gills seem somewhat Analogous (as to their use) to Lungs. But that on the other side, Air is necessary to the Lives even of Fishes, and that therefore 'tis proba∣ble they have some obscure kinde of Re∣spiration, seems manifest by two or three Observations and Experiments, mention'd by divers Authors, who tell us, That Fishes soon die in Ponds and Glasses quite fill'd with Water; if the one be so frozen over, and the other so closely stopp'd, that the Fishes cannot enjoy the benefit of the

Air, if we allow them to be true. But because these Relations are not wont to be deliver'd by Writers upon their own Knowledge; as I shall not reject them, so I dare not build upon them, till I have op∣portunity to examine them by experience. In the mean time, we will adde, That our Engine has taught us two things that may illustrate the matter in hand: The one, That there is wont to lurk in Water, ma∣ny little parcels of interspers'd Air, where∣of it seems not impossible that Fishes may make some use, either by separating it when they strain the Water thorow their Gills, or by some other way: The other, what may be collected from the following Experiment.

We took a large Eele (being able to procure no other Fish alive) and removing it out of the Vessel of Water, wherein it was brought us, into our great Recei∣ver, we caus'd the Air to be pump'd out; and observ'd, That the Eele, after some motion to and fro in the Glass, seem'd somewhat dis-compos'd; and that when we had prosecuted the Exsuction of the Air somewhat obstinately, she turn'd up her Belly, as dying Fishes are wont to do, and from thence-forward lay altogether

moveless, just as if she were stark dead; and though I did not think her so, yet the continuing in that Posture, even after the Cover of the Receiver was taken off (whereby the Air was let in) I shoul•• have been of the Opinion of the By standers, if the Diffidence I am wont to exercise in trying Experiments (especially such as are not usual) had not invited me to take the Fish out of the Receiver, upon which she shew'd her self, by her vivid motions, as much alive as before.

But that is most strange which we ob∣serv'd of a great, g••ay, House Snail (as they call it) which being clos••d up in one of our small Receivers, did not onely, not fall down from the side of the Glass, upon the drawing-out of the Air (For that may be ascrib'd to the tenacity of the Liquor wherewith S••••il, use to stick themselves, even to the smoothest Bo∣dies) but was not so much as depriv'd of progressive motion by the recess of the Air: Though except this Snail, we ne∣ver put any living Creature into our Re∣ceiver, whom it did not either kill, or at least reduce to seem ready to dye. But as we shall not here examine what interest the glutinous, and uneasily dissipable Na∣ture

of the Juices of Snails, may have on this event; so whether this escape of our Eele be to be ascrib'd to the particular and vivacious Nature of this sort of Fishes; or to this, That the Air is not indeed ne∣cessary to the life of Fishes; or finally to this, That though these Animals need some Air, yet they need so little, that that which could not be drawn out of the Receiver, might (at least for a while) suf∣fice them, we will not now determine.

Nor are we at leisure to examine that Paradox of Hippocrates, which some Learned Physitians have of late reviv'd, namely, That the Foetus respires in the Womb: For on the one side it seems ve∣ry difficult to conceive, how Air should traverse the Body of the Mother, and the Teguments of the Childe: And since Nature has, in new-born Babes, contriv'd peculiar and temporary Vessels, that the Blood may circulate thorow other Passa∣ges, then it is wont to do in the same In∣dividuals when they come to have the free use of their Lungs, it seems unlikely, th••t Infants in the Womb do properly respire. But then since our Experiments have manifested, That almost all kinde of Liquors do, as well as Water, abound with

interspers'd Corpuscles of Air, it seems not altogether absurd to say; That when the Foetus is grown big, he may (especial∣ly the upper part of the involving Amni∣os, being destitute of Liquor, and fill'd onely with an halituous Substance) exer∣cise some obscure Respiration, especially, since 'tis not (as many wise Men think it) a Fable, That Children have been heard to cry in the Mothers Womb. For though it happens exceeding rarely, yet some∣times it has been observ'd. And I know a young Lady, whose Friends, when she was some Years since with Childe, com∣plain'd to me, That she was several times much frighted with the Cryes of her In∣fant, which, till I disabus'd Her, She and Her Friends look'd upon as Portentous. And such Observations are the more cre∣dible, because not onely Houswives, but more judicious Persons, mention it, as no very unfrequent thing to hear the Chick Pip or Cry in the Egg, before the Shell be broken. But this I mention but as a probable, not a cogent Argument, till I can discover whether an Elision of an halituous Substance, though noe true Air, may not at the top of the Larynx

produce a Sound, since I find that the Blade of a Knife, held in severall postures in the streame of Vapors (or rarified Wa∣ter) that issu's out of an Aeolipile, will af∣ford various and very audible Sounds.

I had thoughts of conveying into our Receiver young ones, ripped out of the wombe of their Dammes, with their in∣volving Coates intire, but could not pro∣cure them. And I have also had thoughts of trying whether it be not practicable, to make a Receiver, though not all of glasse, yet with little glasse windows, so placed, that one may freely look into it, capacious enough to hold a Man, who may observe severall things, both touching Respiration, and divers other matters; and, who in case of fainting, may, by giving a signe of his weaknesse, be immediately re∣liev'd by having air let in upon him. And it seems not impossible, but that by accusto∣mance, some Men may bring themselves to support the want of Air a pretty while, since we see that divers will live so much longer then other Men under Water: that those that dive for Pearles in the West Indies are said to be able to stay a whole houre under water. And Cardan tels us of one Colanus a Diver in Sicily, who was

able to continue (if Cardan neither mi∣stake, nor impose upon us) three or foure times as long. Not to mind Your Lord∣ship, that You have Your selfe often seen in England, a corpulent Man, who is wont to descend to the bottome of the Thames, and bring out of the deep holes at the bottome of the bankes, large fishes alive in his hands. And Acosta tels us, he saw in Peru the like manner of fishing, but more difficult, practised by the Indians.

I made mention of some Men, and of Accustomance: because there are but ve∣ry few, who, though they use themselves to it by degrees, are fit to support, for ma∣ny Minutes, the want of Air. Insomuch that an ingenious Man of my acquaintance, who is very famous for the usefull skill of drawing Goods, and ev'n Ordnance out of sunke Ships, being asked by mee, how long he was able to continue at the depth of 50. or 60. feet under water, without the use of Respiration, confessed to mee, that hee cannot continue above two mi∣nutes of an houre, without resorting to the Air, which he carries downe with him in a certaine Engine (whereof I can show your Lordship a Description.) Another thing I also learn'd of him by enquiry, that was

not despicable: For asking him, whether he found any use of chawing little spon∣ges dipt in oyle in his Mouth, when he was perfectly under water, and at a distance from his Engine, he told me, that by the help of these sponges he could much lon∣ger support the want of his wonted Respi∣ration, then he was able to do without them. The true cause of which would per∣haps, if discovered, teach us some thing pertinent to the Probleme touching the Respiration of Fishes

But the necessity of Air to the most part of Animals unaccustom'd to the want of it, may best be judg'd of by the follow∣ing Experiments, which we try'd in our En∣gine, to discover whether Insects them∣selves have not, either Respiration, or some other use of the Air equivalent thereunto.

We tooke then an humble-bee, one of those common flyes that are call'd flesh flyes, and one of those hairy wormes that resemble caterpillars, and are wont to be call'd Palmer-wormes: These three wee convey'd into one of our small Receivers, and observ'd to the great wonder of the Beholders, that not onely the Bee, and the Fly fell downe, and lay with their bellies

upwards; but the worme it selfe seem'd to be suddenly struck dead: all of them be∣ing reduc'd to lye without motion, or any other discernable signe of life, within somewhat lesse (if we mistake not) then one minute of an houre. And this, not∣withstanding the smalnesse of the Animals in proportion to the capacity of the ves∣sels: which circumstance we the rather mention, because we found that the vessell was not free from leaks. And to satisfie the Spectators, that 'twas the absence of the Air that caus'd this great and sudden change: we had no sooner re-admitted the Air at the stopcock, than all the three In∣sects began to shew signes of life, and little by little to recover. But when we had a∣gain drawn out the Air, their motions pre∣sently ceased, & they fell down seemingly dead as before, cōtinuing moveless, as long as, by continuing to pump, the vessell was kept exhausted. This invited us thankful∣ly to reflect upon the wise goodnesse of the Creator, who by giving the Air a spring, has made it so very difficult, as men find it, to exclude a thing so necessary to Animals: and it gave us also occasion to suspect that if Insects have no lungs, nor any part analogous thereunto, the ambient

Air affects them, and relieves them at the Pores of their Skin, it not being irratio∣nal to extend to these Creatures that of Hippocrates; who says, That a Living Body is throughout perspirable; or to use his expression, 〈 in non-Latin alphabet 〉〈 in non-Latin alphabet 〉, dispos'd to admit and part with what is Spirituous: Which may be somewhat Illustrated by what we have elsewhere noted▪ That the moister parts of the Air readily insinuate themselves into, and recede from the pores of the Beards of wilde Oates, and those of divers other wilde Plants; which almost continually wreath and unwreath themselves according to, even, the light variations of the temperature of the am∣bient Air.

This Circumstance of our Experiment we particularly took notice of, that when at any time, upon the Ingress of the Air, the Bee began to recover, the first sign of Life she gave, was a vehement pant∣ing, which appear'd near the Ta••l: Which we therefore mention, because we have observ'd the like in Bees drown'd in Wa∣ter, when they first come to be reviv'd by a convenient heat: As if the Air were in the one case as proper to set the Spirits

and Alimental Juice a moving, as heat is in the other; and this may perchance de∣serve a further consideration.

We may adde, That we scarce ever saw any thing that seem'd so much as this Ex∣periment, to manifest, That even living Creatures (Man always excepted) are a kinde of curious Engines, fram'd and con∣triv'd by nature (or rather the Author of it) much more skilfully then our gross Tools and unperfect Wits can reach to. For in our present Instance we see Ani∣mals, vivid and perfectly sound, depriv'd immediately of motion, and any discern∣able signs of life, and reduc'd to a condi∣tion that differs from death, but in that it is not absolutely irrecoverable. This (I say) we see perform'd without any, so much as the least external violence offered to the Engine; unless it be such as is offer'd to a Wind-Mill, when the Wind ceasing to blow on the Sayls, all the several parts remain moveless and useless, till a new Breath put them into motion again.

And this was further very notable in this Experiment; That whereas tis known, that Bees and Flies will not onely walk, but flie for a great while, after their heads

are off; and sometimes one half of the Body will, for divers hours, walk up and down, when it is sever'd from the other: Yet, upon the Exsuction of the Air, not onely the progressive motion of the whole Body, but the very motions of the Limbs do forthwith cease; as if the pre∣sence of the Air were more necessary to these Animals, then the presence of their own Heads.

But it seems, that in these Insects, that fluid Body (whether it bea Juice or Flame) wherein Life chiefly resides, is nothing near so easily dissipable, as in perfect Ani∣mals. For where, as we have above re∣cited, that the Birds we conveyed into our small Receiver were within two minutes brought to be past Recovery, we were unable (though by tyring him that pump'd) to kill our Insects by the exsu∣ction of the Air: For though, as long as the Pump was kept moving, they con∣tinued immovable, yet when we desisted from pumping, the Air that press'd in at the unperceiv'd Leaks, did (though slow∣ly) restore them to the free exercise of the functions of Life.

But, My Lord, I grow troublesome, and therefore shall pass on to other Expe∣riments:

Yet without dispairing of your pardon for having entertain'd you so long about the use of Respiration, because it is a subject of that difficulty to be ex∣plain'd, and yet of that importance to humane Life, that I shall not regret the trouble my Experiments have cost me, if they be found in any degree serviceable to the purposes to which they were design'd. And though I despair not but that here∣after our Engine may furnish us with di∣vers Phaenomena useful to Illustrate the Doctrine of Respiration; yet having not, as yet, had the opportunity to make the other tryals, of various kinds, that I judge requisite for my Information: I must confess to Your Lordship, that in what I have hitherto said, I pretend not so much to establish, or over-throw this or that Hypothesis, as to lay together di∣vers of the Particulars that occur'd to me, in order to a future inquiry. I say, di∣vers of the Particulars, because I could adde many others, but that I want time, and fear that I shall need Your Lordships pardon, for having been so prolix in Wri∣ting; and that of Physitians (which per∣haps I shall more easily obtain) for having invaded Anatomy, a Discipline which

they challenge to themselves, and indeed have been the almost sole Improvers of. Without denying then that the inspir'd and exspir'd Air may be sometimes very useful, by condensing and cooling the Blood that passes through the Lungs; I hold that the depuration of the Blood in that passage, is not onely one of the or∣dinary, but one of the principal uses of Respiration. But I am apt also to suspect, that the Air does something else in Respi∣ration, which has not yet been sufficient∣ly explain'd; and therefore, till I have ex∣amin'd the matter more deliberately, I shall not scruple to answer the Questions that may be asked me touching the ge∣nuine use of Respiration, in the excellent Words employ'd by the acute St. Austin, to one that ask'd him hard Questions: Mallem quidem (says he) corum que à me quaesivisti, habere scientiam quam ig∣norantiam: sed quia id nondum potui, ma∣gis eligo cautam ignorantiam confiteri, quam falsam scientiam profiteri.

HAving (partly upon the consideration of some of the foregoing Experi∣ments, and partly upon grounds not now to be insisted on) entertain'd a suspition, that the action of Corrosive Liquors in the dissolving of Bodies, may be conside∣rably varied by the gravitation or pressure of the incumbent Air, and the removal of it; I thought fit to examine my Con∣jecture by the following Experiment.

I took whole pieces of red Coral, and cast them into as much Spirit of Vinager, as sufficed to swim above an Inch over them: These substances I made choice of, that the Ebullition upon the Solution might not be too great, and that the o∣peration might last the longer.

Having then put about half-a-score Sprigs of Coral, together with the Men∣struum, into a somewhat long neck'd Viol, whereof they seem'd scarce to fill a third part, we convey'd that Viol into one of our small Pneumatical Glasses, containing by ghess about a Quart of Water; and having fastned on the Cover, after the accustom'd manner, we suffered the Li∣quor

to remain unmov'd awhile, to ob∣serve whether the Menstruum would work upon the Coral otherwise then be∣fore. But finding there did onely arise, as formerly, a pretty number of small Bubbles, that made no sensible froth up∣on the surface of the distill'd Vinager, there were made two or three Exsuctions of the Air; upon which, there emerg'd from the Corall such a multitude of Bub∣bles, as made the whole Body of the Menstruum appear white; and soon af∣ter, a Froth, as big as all the rest of the Liquor, was seen to swim upon it: And the Menstruum plainly appear'd to boil in the Glass, like a seething Pot. And though, if we desisted but one minute from pumping, the decrement of the Froth and Ebullition, upon the getting in of a little Air at some leak or other, seem'd to argue, that the removal of the the pressure of the external Air was the cause, or, at least, the occasion of this effervescence: Yet to evince this the more clearly, we turn'd the Key, and let in the external Air at the Stop-cock; immedi∣ately upon whose entrance the Froth va∣nish'd, and so many of the Bubbles with∣in

the body of the Liquor disappear'd, that it lost its whiteness, & grew transparent again: The Menstruum also working as languidly upon the coral, as it did before they were put into the Receiver: But when we had again drawn out the Air, first the whiteness re-ap∣pear'd, then the ebulition was renewd, which, the pumping being a while longer & nimbly pursued, grew so great, that for 3 or 4 times one after another, when ever the Air was let out of the Receiver into the emptyed Cylin∣der; the frothy liquor over-flow'd the glass, & ran down by the sides of it: And yet, upon the readmitting of the excluded air, the boil∣ing Liquor grew immediatly as calm and as transparent as at first: as if indeed the operati∣on of it, upon the Coral, had been facilitated by the exsuction of the incumbent air, w^ch on its recess, left it more easie for the more active parts of the liquor to shew themselves such, then it was whilst the wonted pressure of the Air continued unremoved. It may indeed be suspected, that those vast & numerous Bub∣bles proceeded, not from the action of the Menstruum upon the Corall, but from the suddain emersion of those many little parcels of air that (as we formerly observd) are wont to be dispers'd in liquors, without excluding Spirit of Vinegar; but having had this suspi∣tion before we tryd the Experiment, we con∣vey'd

our distill'd Vinager alone into the Re∣ceiver, and kept it awhile there, to free it from its Bubbles (which were but very small) be∣fore ever we put the Corall into it. It may be suspected likewise, that the agitation of the Liqour, necessary following upon the shaking of the Glass, by pumping, might occasion the recited Ebullition, but upon tryal made, there appear'd not any notable change in the liquor, or its operation, though the containing Vessel were shaken, provided no Air were suck'd out of it. The former Experiment was another time tryd in another small Receiver, with Co∣ral grosly poudred, and the success was very much alike, scarce differing in any thing, but that the Coral being reduc'd to smaller parts, upon the ebullition of the liquor, so many lit∣tle lumps of Coral would be carryed & Boy'd up by the emerging Bubbles, as sometimes to darken the Viol; though the same Coralline Corpuscles would be let fall again upon the letting in of the Air.

Something also we try'd in our great Receiver, concerning the solution of Metals in Aqua fortis, and other Corrosive Liquors; but partly the stink, and partly some accidents, kept us from observing any thing peculiar & remarkable about those Solutions.

One thing we must not omit, that when the Spirit of Vinager was boiling upon the Coral, we took off the Cover of the Receiver, and took out the Viol, but could not finde, that notwithstanding so very late an Ebullition, the Liquor had any heat great enough to be at all sensible to our hands.

WE will now subjoyn an Experi∣ment, which, if the former did not lessen, the wonder of it would pro∣bably appear very strange to Your Lord∣ship, as it did to the first Spectators of it.

The Experiment was this: We caus'd Water to be boyl'd a pretty while, that by the heat it might be freed from the la∣titant Air, so often already taken notice of in common Water: Then almost fil∣ling with it a Glass Viol, capable of con∣taining near four Ounces of that Liquor; we convey'd it, whil'st the Water was yet hot, into one of our small Receivers (big enough to hold about a pound of Water) and having luted on the Cover, we caus'd the Air to be drawn out: Upon the two first Exsuctions, there scarce appear'd any change in the Liquor, nor was there any notable alteration made by the third; but at the fourth, and afterwards, the Water appear'd to boyl in the Viol, as if it had stood over a very quick Fire; for the Bubbles were much greater then are usu∣ally found upon the Ebullition of very

much more Water then was contain'd in our Viol. And this Effervescence was so great in the upper part of the Water, that the Liquor boyling over the top of the Neck a pretty deal of it ran down into the Receiver, and sometimes continued (though more languidly) boyling there. Prosecuting this Experiment, we observ'd, that sometimes, after the first Ebullition, we were reduc'd to make divers Exsucti∣ons of the Air, before the Liquor would be brought to boyl again. But at other times, as often as the Key was turn'd to let the Air pass from the Receiver into the Pump, the Effervescence would be∣gin afresh, though the Pump were ply'd for a pretty while together; which seem'd to argue, that the boyling of the Water proceeded from hence, That upon the withdrawing the pressure of the incumbent Air, either the Fiery Corpuscles, or ra∣ther the Vapors agitated by the heat in the Water (which last, what we have for∣merly noted touching the rarefied Wa∣ter of an Aeolipile, manifest to be capa∣ble of an Elastical Power) were permit∣ted to expand themselves mightily in the evacuated Receiver; and did, in their

tumultuous Dilatio, lift up (as the Air is wont to do) the uppermost part of the Water, and turning it into Bubbles, made the Water appear boiling. This conjecture was further confirm'd by these additional Circumstances: First, The Effervescence was confin'd to the upper part of the Water, the lower remain∣ing quiet, unless the Liquor were but shallow. Next, although sometimes (as is already noted) the Ebullition began a∣gain, after it had ceas'd a pretty while, which seem'd to infer, That some concur∣rent cause (whatever that were) did a little Modifie the operation of heat; yet, when the water in the Viol could by no pum∣ping be brought to boil any more, the self-same Water, being in the very same Viol warm'd again, and reconvey'd into the Pneumatical Glass, was quickly brought to boyl afresh, and that vehe∣mently and long enough; not to menti∣on, that a new parcel, taken out of the same parcel of the boyled Water with the former, and put in cold, could by no pumping be brought to the least shew of Effervescence. Besides, having try'd this Experiment in hot Sallet Oyl, be∣ing

a much more tenacious Liquor, and requiring a stronger heat to make it boil, could not be brought to an Effer∣vescence in our Reciver; whereas the Chymical Oyl of Turpentine, being thinner and more volatile, was present∣ly made to boyl up, till it reach'd four or five times its former height in the Viol, in whose bottom it lay, and con∣tinu••d boyling till it was almost reduc'd to be but luke-warm. Wine also be∣ing a more thin and spirituous Liquor then Water, being convey'd in hot in∣stead of the Oyl, did, as I remember, at the very first Exsuction begin to boyl so vehemently, that, in a short time that the Pump was kept moving, four parts of five, by our ghess, boyl'd over out of the Viol, though it had a pretty long Neck. On which occasion we will adde, that even the Water it self, near one half, would sometimes boyl over into the Receiver before it became luke-warm. And it was also remarkable, that once, when the Air had been drawn out, the Liquor did, upon a single Exsucti∣on, boyl so long with prodigiously vast Bubbles, that the Effervescence lasted al∣most

as long as was requisite for the re∣hearsing of a Pater Noster. Now the Experiment having been try'd more then once, and found to succeed as to the main, seems much to countenance the conjecture we made at the beginning of this Letter, where we told your Lordship, That per∣haps the pressure of the Air might have an interest in more Phaenomena then men have hitherto thought. For as we had not then made this Experiment, so now we have made it, it seems to teach, That the Air, by its stronger or weaker pres∣sure, may very much Modifie (as the School-men speak) divers of the Opera∣tions of that vehement and tumultuous Agitation of the small parts of Bodies, wherein the nature of heat seems chiefly, if not solely, to consist. Insomuch that if a heated Body were convey'd above the Atmosphere, 'tis probable that the heat may have a differing operation, as to the power of dissipating the parts of it, from what it has here below.

To conclude, This Experiment might have been further prosecuted, but our want of leasure makes us content our selves to adde at present; That perhaps

it would not be lost labor if this were try'd, not onely with other Liquors, but with variety of heated, and especially soft or melted Bodies: But in such cases the Receiver ought to be so shap'd, as is most proper to preserve the Cement wherewith the Cover must be fastned on, from being melted by the heat of the included Mat∣ter; the inconvenience to be hereby a∣voided, having befallen us in the use of a Receiver too shallow, though otherwise capacious enough.

Notes

• Gale••us de usu, Part: lib: 3.
• Isa. 28.29.
• Fontanus apud Bar∣tholin: lib. 2. cap. 9.
• Epist. 3.
• Fraelichius apud Va¦ren: Geo∣gra: Gener: lib. 1. cap. 19.
• Cardan. de Subtilitat. lib. 11.
• lib 3. c. 15.
• Experi∣ment 42.
• Experi∣ment 43.