Now of this Experiment there are two or three Circumſtances yet to be men­tion'd, which are no leſs then thoſe alrea­dy recited, pertinent to our preſent pur­poſe.

In the firſt place then, when the great­er part of the Air had been pump'd out of the Receiver, the riſing bubbles aſcend­ed ſo very ſlowly in the Pipe, that their Progreſs was ſcarce diſcernable; which ſeem'd to proceed from this, That their bigneſs was ſuch, That they could not ſufficiently extend themſelves in the cavity of the Glaſs, without preſſing on both hands againſt the ſides of it, whereby they became of more difficult extruſion to the Water. And though it may ſeem ſtrange theſe bubbles ſhould be of any conſiderable bulk, ſince 'tis like they conſiſted of leſſer parcels of the Air lurking in the Water, then thoſe that were vigorous enough to make their way through long before them: yet they were commonly much larger then before, ſome of them being equal in quantity to four or five Peas: Whether this their in­creaſe of bulk proceeded from the greater decrement of the preſſure of the Air, or from the Union of two or three of thoſe numerous bubbles which were then generated below the bottom of the Pipe, where we could not ſee what was done a­mong them.

Another thing we noted in our bubbles was, That whereas in ordinary ones the Air, together with the thin film of Water that inveſts and detains, is wont to ſwell above the ſurface of the Water it ſwims on, and commonly to conſtitute Hemiſ­pherical Bodies with it, the little parcels of Air that came up after the Receiver was pretty well empty'd, did not make protuberant bubbles, but ſuch whoſe up­per ſurface was either level with or be­neath that of the Water, ſo that the up­per ſurface being uſually ſomewhat con­vex, the leſs protuberant parts of it had a pretty quantity of Water remaining a­bove them.

We alſo further obſerv'd, That where­as in the bubbles that firſt appear'd in the Pipe, the aſcending Air did, as in o­ther common bubbles, make its way up­wards, by dividing the Water through which it paſſ'd, in thoſe bubbles that ap­pear'd at the latter end of our Experi­ment, when the preſſure of the little ex-ternal Air, remaining in the Receiver, was grown inconſiderable, the aſcending parcels of Air having now little more then the weight of the incumbent Water to ſurmount, were able both ſo to expand themſelves as to fill up that part of the Pipe which they pervaded, & by preſſing every way againſt the ſides of it, to lift upwards with them what Water they found above them, without letting any conſiderable quantity glide down along the ſides of the Glaſs: So that ſometimes we could ſee a bubble thruſt on before it a whole Cylinder of Water of perhaps an Inch high, and carry it up to the top of the Pipe; though as we formerly no­ted, upon the letting in the external Air, theſe tumid bubbles ſuddenly relapſ'd to their former inconſpicuouſneſs.

All theſe things laid together ſeem'd ſufficiently to confirm that, which the conſideration of the thing it ſelf would eaſily enough perſwade, namely, That the Air, and ſuch like Bodies being under Water, may be preſſ'd upon as well by the Atmoſphere, as by the weight of the incumbent Water it ſelf.

Hence likewiſe we may verifie what we obſerv'd at the cloſe of the foregoing Experiment, namely, That from the ſole ſwelling of Water there recorded, it can­not be ſo ſafely concluded that Water, when freed from compreſſion, is endowd with an Elaſtical power of expanding it ſelf, ſince thereby it appears that the In­tumeſcence produc'd by that Experiment, may (at leaſt in great part) be aſcrib'd to the numerous little bubbles which are wont to be produc'd in Water, from which the preſſure of the Atmoſphere is in great meaſure taken off. So apt are we to be miſ-led, even by Experiments them­ſelves, into Miſtakes, when either we con­ſider not that moſt Effects may proceed from various Cauſes, or minde onely thoſe Circumſtances of our Experiment, which ſeem to comply with our preconceiv'd Hypotheſis or Conjectures.

And hence it ſeems alſo probable, that in the Pores or inviſible little receſſes of Water it ſelf there lie commonly inter­ſperſ'd many parcels of either Air, or at leaſt ſomething Analogous thereunto, al­though ſo very ſmall that they have not been hitherto ſo much as ſuſpected to lurk there. But if it be demanded how it appears that there is interſperſ'd through the Body of Water any ſubſtance thinner then it ſelf, and why that which produc'd the bubbles above mention'd ſhould not be reſolutely ſaid to be nothing elſe then a more active and ſpirituous part of the Water, we ſhall, in order to the Elucida­tion of this matter, ſubjoyn to what was formerly deliver'd the following Ex­periment.

WE recited in our nineteenth Ex­periment, how by drawing moſt of the Air out of the Receiver, we made the Water ſubſide by degrees in a Glaſs not four Foot long: We ſhall now adde, that in the like Experiment made in ſuch a Tube, or a greater, it may be obſerv'd, That when the Water begins to fall, there will appear ſtore of bubbles faſten'd all a­long to the ſides of the Glaſs; of which bubbles, by the agitation of the Veſſel conſequent upon pumping, there will ariſe good numbers to the top of the Water, and there break; and as the Cylinder of Water is brought to be lower and lower, ſo the bubbles will appear more numerous in that part of the Tube which the Water yet fills; and the nearer the ſurface of the Water, in its deſcent, approaches to theſe bubbles, the greater they will grow, be­cauſe having the leſs weight and preſſure upon them, the Expanſion of that Air which makes them, can be the leſs reſiſted by the preſſure of the incumbent Water and Air; as ſeems probable from hence, that upon the letting in a little external Air, thoſe bubbles immediately ſhrink.

Experi­ment 22.

It may indeed, as we lately intimated, be conjectur'd, that theſe bubbles pro­ceed not ſo much from any Air pre-exi­ſtent in the Water, and lurking in the Pores of it, as from the more ſubtle parts of the Water it ſelf; which by the expan­ſion allow'd them upon the diminiſh'd preſſure of the ambient Bodies may gene­rate ſuch bubbles. And indeed, I am not yet ſo well ſatisfied that bubbles may not (at leaſt ſometimes) have ſuch an Origina­tion: but that which makes me ſuſpect that thoſe in our tryals contain'd real Air formerly latitant in the Pores of the Wa­ter, is this, That upon the inletting of the external Air, the Water was not again impell'd to the very top of the Tube whence it began to fall, but was ſtopt in its aſcent near an Inch beneath the top. And ſince, if the upper part of the Tube had been devoyd of any other then ſuch Ethereal matter as was ſubtle enough freely to penetrate the pores of the Glaſs, the external Air would have been able to impel the Water to the top of a Tube ſeven or eight times as long as ours was; The Phænomenon under conſi­deration ſeem'd manifeſtly to argue that the many bubbles that broke at the top of the Water did contain a real Air, which, being collected into one place and hinder'd by the top of the Glaſs from re­ceding, was able to withſtand the preſſure of the outward Air. As we ſee that if never ſo little Air remain in the Tube up­on the making the Experiment De Vacuowith Quick-ſilver, no inclining of the Tube, though a long one, will enable a Man to impel the Mercury up to the very top, by reaſon (as we formerly noted) of the reſiſtance of the included Air, which will not be compreſſ'd beyond a certain degree.

But in order to a further Diſcovery what our bubbles were, we will, on this occa­ſion, inform Your Lordſhip that we try'd the XIXth Experiment in one of our ſmall Receivers, and ſound, that upon the draw­ing down of the Water, ſo many bubbles diſcloſ'd themſelves and broke into the upper part of the Tube, that having after­wards let in the external Air, the Water was not thereby impell'd to the top of the Tube (three Foot in length) within a lit­tle more then half an Inch. And whe­ther or no it were Air that poſſeſſ'd that ſpace at the top of the Tube which was not fill'd with Water, we took this courſe to examine. We drew the ſecond time the Air out of the Receiver, and found, that by reaſon of the body that poſſeſſ'd the top of the Tube, we were able not onely to make the Water in the Tube fall to a level with the ſurface of the Water in the Veſſel: But alſo (by plying the Pump a little longer) a great way beneath it: which ſince it could not well be aſcrib'd to the bare ſubſiding of the Water by rea­ſon of its own weight, argued that the Wa­ter was depreſſ'd by the Air: which was confirm'd by the Figure of the ſurface of the Water in the Tube, which was much more concave then that of Water in Tubes of that bigneſs uſes to be. And this further tryal (to adde that upon the by) we made at the ſame time, That when the Water in the Pipe was drawn down almoſt as low as the Water without it, we obſerv'd, that (though we deſiſted from pumping) by the bare application of a hand moderately warm to the deſert­ed part of the Tube, the remaining Wa­ter would be ſpeedily and notably de­preſſ'd. And having for a while held a kindled Coal to the outſide of the Tube, (the Pump being ſtill unimploy'd, becauſe the Veſſel chanced to hold extraordinarily well) the Air was by the heat ſo far ex­panded, that it quickly drave the Water to the bottom of the Tube, which was divers Inches beneath the ſurface of the ambient Water. Whereby it appears (by the ſame way by which we formerly mea­ſur'd the dilatation of the Air) that the Air, even when it is expanded to between 90 and 100 times, its extent will yet rea­dily admit of a much further rarifaction by heat.

I conſider'd alſo that in caſe the Bub­bles we have been ſpeaking of, were pro­duc'd by the parcels of Air latitant in the Water, that Air being now got together to the top of the Tube, though the Air were again drawn out of the Receiver, the taking off its preſſure would not diſ­cloſe bubbles as before; and accordingly, the Air being again pump'd out, the Wa­ter in the Tube deſcended as formerly: but for a great while we ſcarce ſaw one bubble appear, onely when the Receiver had been very much exhauſted, and the Water was fallen very low, there appear'd near the bottom of the Tube, certain little bubbles, which ſeem'd to conſiſt of ſuch parcels of Air as had not, by reaſon of their ſmalneſs, got up to the top of the Water, with the more bulkie and vi­gorous ones. And that which is not in­conſiderable, is, That having, by letting in the Air, forc'd up the Water into the Tube, we could not perceive that it aſ­cended nearer the top, though we per­mitted the Engine to remain unimploy'd for two or three Nights together, and watch'd whether the Water would ſwell up and fill the Tube. And on this occa­ſion I remember, that having try'd ſuch an Experiment as this with Quick-ſilver in­ſtead of Water, in a Tube of about a Foot and a half long, wherein it might ſeem more hopeful to eſcape bubbles; yet up­on the drawing down the Quick-ſilver as low as we could, and letting in the exter­nal Air upon it, we found that ſome lurk­ing particles of Air were got up to the top of the Tube, and hinder'd the Quick­ſilver from being forc'd up again ſo high. And though the Quick-ſilver were by this means brought to appear a very cloſe and lovely Metalline Cylinder, not inter­rupted by interſperſ'd bubbles as before; yet having cauſ'd the Air to be again drawn out of the Receiver, I could per­ceive ſeveral little bubbles to diſcloſe themſelves, faſten'd to the inſide of the Tube, near the bottom of it; and having purpoſely watch'd one or two of the chief­eſt, I had the pleaſure to obſerve, that though they grew bigger and bigger as the ſurface of the Mercurial Cylinder fell nearer and nearer to them, ſo as that at length they ſwell'd into a conſpicuous bulk; yet upon the wary letting in the Air upon them, they did not break, but preſently ſhrunk up into a littleneſs that render'd them inconſpicuous.

Whence it ſeems very probable, if not certain, that even in the cloſeſt and moſt ponderous Liquors, and therefore much more in Water, there may lurk undiſcern­able parcels of Air, capable, upon the removal of the preſſure of the ambient Air (though but in part) and that of the Liquor wherein it lurks, to produce con­ſpicuous bubbles. And conſequently, if it ſeem inconvenient to admit an Elaſtical power in the Water, it may be ſaid that the ſwelling of the compreſſ'd Water in the Pewter Veſſel lately mention'd, and the ſpringing up of the Water at the hole made by the Needle, were not the effects of any internal Elater of the Water, but of the ſpring of the many little particles of Air diſperſ'd through that Water, and acting upon it in their ſudden recovering themſelves to a greater extent, then that to which a violent compreſſion had re­duc'd them.

But though, from all theſe particulars, it ſeems manifeſt that the bubbles we have been all this while treating of, were pro­duc'd by ſuch a ſubſtance as may be pro­perly enough call'd Air; yet till we ſhall have had the opportunity of making ſome further tryals concerning the nature of the Air, we ſhall not reſolutely deter­mine whether or no Air be a Primogenial Body (if I may ſo ſpeak) that cannot now be generated or turn'd either into Water or any other Body. Yet in the mean while (becauſe it is an important Queſtion, and if rightly determin'd, may much conduce to the knowledge of the nature of the Air) We think it not unfit to make a brief mention of ſome of the particulars which at preſent occur to our thoughts in favor of either part of the Queſtion.

Firſt then, divers Naturaliſts eſteem the Air (as well as other Elements) to be in­generable and incorruptible. And reaſons plauſible enough may be drawn to coun­tenance this Opinion from the conſidera­tion of that permanency that ought to belong to the corporeal Principles of o­ther Bodies.

Next, Experience may be pleaded to the ſame purpoſe, for I have read of ſome who have in vain attempted to turn Air into Water, or VVater into Air.

The diligent Schottus tells us, That a­mongſt the other rarities to be met with in that great Repoſitory of them, the Muſæum Kercherianum, there is a round Glaſs with a tapering Neck near half full (as one may gueſs by the Scheme he an­nexes) of ordinary Spring-water, which having been Hermetically ſhut up there by Clavius the famous Geometrician, The included water is to this day pre­ſerv'd, not onely clear and pure, as if it were but newly put in: But (as it ſeems) without (in the leaſt) turning into Air, notwithſtanding its having been kept there theſe fifty years: For he tells us, That the Water hath continued there all this while without any diminution.

Schottus Part 3. Claſſ. 1.

Nor does it appear in thoſe Glaſſes, which for Chymical Experiments we uſu­ally cloſe with Hermes his Seal (as they call it) that the included Air does, during its long Impriſonment, notwithſtanding the alteration it receives from various de­grees of heat, diſcernably alter its nature. Whereas we plainly perceive in our Dige­ſtions and Diſtillations, that though it may be rarified into inviſible Vapors, yet it is not really chang'd into Air, but onely divided by heat, and ſcatter'd into very minute parts, which meeting together in the Alembick or in the Receiver, do pre­ſently return into ſuch Water as they con­ſtituted before. And we alſo ſee, that ev'n Spirit of Wine, and other ſubtle and fugitive Spirits, though they eaſily fly in­to the Air, and mingle with it, do yet in the Glaſſes of Chymiſts eaſily lay aſide the diſguiſe of Air, and reſume the deve­ſted form of Liquors. And ſo volatile Salts, as of Urine, Harts-horn, &c. though they will readily diſperſe themſelves through the Air, and play up and down in the capacity of an Alembick or a Recei­ver: yet will they, after a while, faſten themſelves to the inſides of ſuch Glaſſes in the form of Salts.

Beſides, ſince Air is confeſſedly en­dow'd with an Elaſtical power that proba­bly proceeds from its Texture, it appears not what it is that in ſuch light alterations of Water, as are by many preſum'd ca­pable of turning it into Air, can be rea­ſonably ſuppoſ'd ſo to contrive the Parti­cles of Water, as to give them, and that permanently, the ſtructure requiſite to a Spring. I adde the word, Permanently, becauſe the newly mention'd obſervations ſeem to argue the Corpuſcles of Air to be irreducible into Water, whereas the Aqueous Particles may perhaps for a while be ſo vehemently agitated, as to preſs almoſt like Springs upon other Bo­dies; yet upon the ceaſing of the agitati­on, they quickly, by relapſing into Wa­ter, diſcloſe themſelves to have been no­thing elſe whil'ſt they counterfeited the Air.

Laſtly, The Experiment formerly made in our Engine with a piece of Match, ſeems to evince, that even thoſe light and ſubtle Fumes (for the moſt part not aque­ous neither) into which the Fire it ſelf ſhatters dry Bodies, have no ſuch Spring in them as the Air, ſince they were unable to hinder or repreſs the expanſion of the Air included in the Bladder they ſurroun­ded.

I remember indeed that the Learned Foſephus Acoſta, in his Hiſtory of the Weſt Indies, tells us, That he ſaw in thoſe parts ſome Grates of Iron ſo ruſted and conſum'd by the Air, that the Metal be­ing preſſ'd between the Fingers, diſſolv'd (to uſe his words) to powder, as if it had been Hay or parched Straw. And I re­member too, that the accurate Vareniustells us, That in the Iſlands commonly called Azores, the Air (and Wind) is ſo ſharp, that in a ſhort time it frets not only Iron Plates, but the very Tiles upon the Roofs of Houſes, and reduces them to duſt. And I have elſewhere mention'd ſome recent Obſervations of this kinde. But it may be ſaid, That the above-men­tion'd Authors aſcribe the recited effects chiefly to the Winds, and that however the corroſion of the Iron and the Tiles may proceed not from the Air it ſelf, or any of its genuine parts, but from ſome ſaline Corpuſcles diſperſ'd through the Air, and driven by the Winds againſt the Bodies it is preſum'd to fret. And that ſuch volatile Salts may copiouſly aſcend into the Air, and yet retain their Nature, as doth the more fixt Salt in the Sea Wa­ter, the ſublimations of Sal-Armoniackmay ſufficiently evince. Not to mention that I have ſhown ſome Friends a ſecret kinde of ſaline Subſtance incomparably ſubtler then Sal-Armoniack, which did not onely eaſily enough aſcend it ſelf, but carried up with it (and that in a very great proportion) the ſolid and ponderous Bo­dy ev'n of uncalcin'd Gold in the form of ſubtle exhalations, which did afterwards faſten themſelves to the upper parts of the Veſſels, and yet manifeſt themſelves to continue Gold. We remember alſo, that to try whether Water could be turn'd into Air, we once took an Æolipile, into which we had before convey'd ſome Wa­ter, and placing it upon kindled Coals when the heat forc'd out a vehement ſtream of aqueous Vapors; we ty'd about the neck of it, that of a Bladder, which we had before empty'd of Air; and find­ing the Æolipile after a while to blow up the Bladder, we carefully ty'd it again that the included ſubſtance might not get away. Then ſlipping it off from the Æo­lipile we convey'd it into our Receiver, to try whether or no that which in part di­ſtended the Bladder would appear by its Spring to be true Air: whereby we found that upon the exſuction of the ambient Air, the included ſubſtance expanded it ſelf and the Bladder to a very much great­er bulk then it was of before. And for further ſatisfaction, having again taken out the Bladder, we ſuffer'd it to remain ty'd up till next morning, to try whether time, and the coldneſs of the night, would make the contain'd ſubſtance relapſe in­to Water: But the next Morning we found it little leſs tumid then before. I remember, I ſay, that I once made this Experiment; but I might ſay in anſwer to it, that the chief reaſon of my men­tioning it, is, To let Your Lordſhip ſee how requiſite it is to be circumſpect and conſiderate, when we are to make and to build upon nice Experiments. For though I may ſeem to have uſed ſufficient cauti­on, yet afterward conſidering with my ſelf that the Æolipile I had imploy'd was a very large one, and that it required much more care then one that has not try'd it would imagine, to drive out all the Air from a large Æolipile, I eaſily ſuſpected that the diſtenſion of the Bladder in our pneumatical Veſſel, might proceed not from the Watery ſteams that came out at the narrow mouth of the Æolipile, and had very much wetted the Bladder, but from the rarified Air which in that ſort of Veſſels is wont for a good while together to come out with the rarified Water: and accordingly having reiterated the Experi­ment I found it very difficult (by rea­ſon of the ſhrinking of the Bladders (up­on their being heated) and of other impe­diments) to make it ſo accurately as to de­duce from it, that Water may be rarified into true Air.

Natural & Hiſt. In­, Lib. 3. 9.

Geogr. Ge­ral. Lib. 19.

Againſt the four other above-mention'd Conſiderations, we cannot ſpend time to frame Objections, but muſt forth with proceed to the mention of thoſe things that ſeem to argue that Air (at leaſt ſuch as produc'd our bubbles) maybe gene­rated of Water and other Bodies.

Firſt then we have found by Experi­ence that a vapid Air, or Water rarified into vapor, may at leaſt for a while emu­late the elaſtical power of that which is generally acknowledg'd to be true Air. For if you take a good Æolipile, with a moderately ſtrong and ſlender Neck, and filling it with Water, lay it upon quick Coals, you may after a while obſerve ſo great a preſſure by ſome of the parts con­tain'd in the Æolipile upon others, that the Water will ſometimes be thrown up into the Air above three or four Foot high; and if you then take the Æolipilealmoſt red hot from off the Fire, you may perceive that the Water will for a longer time then one would eaſily imagine con­tinue to be ſpouted out in a violent Stream. And if there remains but little Water in the Æolipile when tis taken ve­ry hot from the Fire, immerfing the Neck of it into cold Water, you will finde, that after it begins to ſuck in ſome Water, there will be made from time to time ſtore of large bubbles in that Water where into the neck was plunged. Which bubbles ſeem manifeſtly to proceed from hence, that for a while the heat in the Æ­olipile continues ſtrong enough to rarifie part of the Water that is ſuck'd in, and expel it in the form of Vapors through the Water incumbent on the Pipe. If al­ſo when the Æolipile is almoſt full of wa­ter, and therefore can contain but little Air; you hold a Coal or Brand in that ſtream of Vapors that iſſues out of the narrow mouth of it, you will finde this vapid or rorid Air, (if I may ſo call it) to blow the Fire very ſtrongly and with a roaring noiſe. And that it be not ſaid that 'tis by the external Air which the a­queous ſteams drive before them, and not by the Steams themſelves, that the Blaſt is made and the Flame excited; it has been obſerv'd, that by approaching the Coal or Brand almoſt to the mouth of the Æolipile, the winde appear'd more vehement then if the Body to be kindled were held ſome Inches off.

But in regard the elaſtical power of the Stream, iſſuing out of an Æolipile, ſeems manifeſtly due to the heat that expands and agitates the aqueous Particles where­of that Stream conſiſts, and that ſuch rapid winds ſeem to be but water ſcatter'd into little parts and ſet a moving; ſince we finde, that holding a Knife, or any ſolid, ſmooth and cloſe Body againſt the ſtream that iſſues out of the Æolipile, the vapors condenſing upon it, will preſently cover it with water: It will be very per­tinent to ſubjoyn a notable Experiment that I remember I have met with in the deſcription given us by the Induſtrious Kircher, of ſeveral Muſical Engines. And (though it may ſeem ſomewhat prolix) we will recite what he delivers in his own words, which are theſe.

Cum codem tempore quo hæc ſcripſiſummi Pont: Innocentii Xmi mandato or­gani hydraulici in horto Quirinali conſti­tuendi cur a mihi commendata eſſet; Æoliam camer am inſigni ſane ſucceſſu conſtrui juſsi­mus, eá quæ ſequitur ratione.

Kirch: Art: Mag: Con: & Diſſon: lib. 9. p. 309.

Erat longitudo ſive altitudo cameræ AH 5 Pedum, Latitudine 3 fere ex lateribusconſtructa; in medio duo tenebat Diaphrag­mata CD & EJ in modum cribri pluri­bus for aminibus pertuſa. Paulo infra ca­nalis G aquam advehens inſerebatur in H eidem epiſtomium par ab at exitum. Aqua it áque per canalem G maximo impetu ruens vehementiſsimum ventum mox intus exci­t ab at; qui ventus nimia humiditate imbu­tus, ut purior exiret ſiccior〈qué〉, Diaphrag­mata ill a in cribri modum pertuſa, or dinata ſunt. Intra hæc enim aquæ vehemens agi­tatio rupta fracta〈qué〉 aerem puriorem per A canalem ſubtilioremque emittebat: Verum cum poſtea inventum ſit aerem plus æquo humi­dum interioribus Organi meatibus maximum detrimentum inferre: Hinc ut aer aquoſusſicciſsimam conſiſtentiam acquireret, ordina­vimus canalem plumbeum QR in helicem contortum vaſi S aliquantulum capaciori in modum Urnæ efformato, inſertum. Intra urnam enim plumbeam & canalem tortuo­ſum illiſus aer humidus, it a ab omni aquoſi­tate defæcabatur, ut ex furno in Organum derivatus dici potuerit. Urna S canalis tortuoſus QR ultimum orificium Q inſe­ritur anemothecæ organi. Et hunc modum organis hydraulicis omnium aptiſsimum reperi.

See the fif­teenth Fi­gure.

Debet autem cameræ illa ſituari in loco quantum fieri poteſt ſicciori it a ut longo ca­nali aqua intr a eam derivetur ne locus hu­miditate ſua Organis officiat.

Thus far the Ingenious Kircherus, whom I the rather cite, becauſe although I have been informed of divers Ventiducts (as they call them) by very knowing Tra­vellers that have obſerv'd them: Yet this relation of our Author being very pun­ctual, and deliver'd upon his own particu­lar Experience, has, I confeſs, made me wiſh I had had the good fortune when I was at Rome, to take notice of theſe Or­gans; or that I had now the opportunity of examining of ſuch an Experiment. For if upon a ſtrict inquiry I ſhould find that the breath that blows the Organs does not really upon the ceaſing of its un­uſual agitation by little and little relapſe into water, I ſhould ſtrongly ſuſpect that 'tis poſſible for Water to be eaſily turn'd into Air. I remember indeed, that we have formerly taught that there lurks an interſperſed Air in the pores of ordinary Water, which may poſſibly be ſtruck out by the breaking of the Water in its fall into the Æolian Chamber, (as he calls it.) But in regard the Scheme ſeems to repre­ſent that Chamber as cloſely ſhut, and thereby forbids us to ſuppoſe that any Air is carried into it but what is latitant in the Water, it will ſcarce ſeem probable to him who remembers how ſmall a propor­tion of Air, that appear'd to be when its rarification ſeaſed, which was conceal'd in the Water we freed from bubbles in our Receiver, that ſo little Air as is common­ly diſperſ'd through Water, ſhould be a­ble, in ſo little Water as was requiſite for ſo ſmall a room, to make ſo vehement a Wind as our Author here tells us of. I have ſometime therefore ſuſpected, that in this caſe the Wind may be produc'd by ſmall particles of the water it ſelf, forci­bly expell'd out of the Chamber into the Organs. And to the Objection to which I foreſaw this gheſs to be liable, namely, That, no heat intervening, there appear'd nothing that ſhould raiſe the Water into exhalations and give them an impulſe. I thought it might be ſaid that motion a­lone, if vehement enough, may, with­out ſenſible heat, ſuffice to break Water into very minute parts, and make them aſ­cend upwards, if they can no where elſe more eaſily continue their agitation. For Iremember, that Travelling betwixt Ly­ons and Geneva, I ſaw, not very far out of the Way, a place where the River of Rhone coming ſuddenly to be ſtreighten'd betwixt two Rocks, ſo near each other, that a Man may (if my Memory fail me not) ſtand aſtride upon both at once: that rapid Stream daſhing with great impetuo­ſity againſt its Rocky Boundaries, does break part of its Water into ſuch minute Corpuſcles, and put them into ſuch a mo­tion, that Paſſengers obſerve at a good di­ſtance off, as it were a Miſt ariſing from that place, and aſcending a good way up into the Air. Such, I ſay, was my ſuſ­picion touching the Wind we have been conſidering, but it ſeems ſomething odde that aqueous Vapors ſhould, like a dry Wind, paſs through ſo long and tortu-ous a Pipe of Lead, as that deſcrib'd by our Author, ſince we ſee in the Heads of Stills, and the Necks of Æolipiles, how quickly ſuch vapors are even by a very lit­tle cold recondenſed into Water. But to this alſo ſomething may be ſpeciouſly reply'd; wherefore contenting my ſelf to have mention'd our Authors Experiment as a plauſible, though not demonſtrative proof, that Water may be tranſmuted in­to Air. We will paſs on to mention in the third place another Experiment, which we try'd in order to the ſame enquiry.

We took a clear Glaſs bubble (capable of containing by gheſs about three Oun­ces of Water) with a Neck ſomewhat long and wide, of a Cylindrical form; this we fill'd with Oyl of Vitriol and fair water, of each almoſt a like quantity, and caſting in half a dozen ſmall Iron Nails, we ſtopt the mouth of the Glaſs (which was top-full of Liquor) with a flat piece of Diapalma provided for the purpoſe, that accommodating it ſelf to the ſurface of the water, the Air might be exqui­ſitely excluded: and ſpeedily inverting the Viol, we put the Neck of it into a ſmall wide-mouth'd Glaſs that ſtood rea­dy with more of the ſame Liquor in it, to receive it. As ſoon as the neck had reach'd the bottom of the Liquor it was dipp'd into, there appear'd at the upper part (which was before the bottom) of the Viol a bubble, of about the bigneſs of a Pea, which ſeem'd rather to conſiſt of ſmall and recent bubbles, produc'd by the action of the diſſolving Liquor upon the Iron, then any parcel of the external Air that might be ſuſpected to have got in upon the inverſion of the Glaſs, eſpeci­ally ſince we gave time to thoſe little Particles of Air which were carried down with the Nails into the Liquor to fly up again. But whence this firſt bubble was produced, is not ſo material to our Expe­riment, in regard it was ſo ſmall: For ſoon after we perceiv'd the bubbles produced by the action of the Men­ſtruum, upon the Metal aſcending co­piouſly to the bubble already named, and breaking into it, did ſoon exceedingly in­creaſe it, and by degrees depreſs the wa­ter lower and lower, till at length the ſub­ſtance contain'd in theſe bubbles poſſeſſed the whole cavity of the Glaſs Viol, and almoſt of its Neck too, reaching much lower in the Neck then the ſurface of the ambient Liquor, wherewith the open­mouth'd Glaſs was by this means almoſt repleniſhed. And becauſe it might be ſuſpected that the depreſſion of the Li­quor might proceed from the agitation whereinto the exhaling and impriſon'd ſteams were put, by that heat which is wont to reſult from that action of corro­ſive ſalts upon Metals, we ſuffered both the Viol and the open-mouthed Glaſs to remain as they were, in a Window, for three or four days and nights together; but looking upou them ſeveral times during that while, as well as at the expiration of it, the whole cavity of the Glaſs bubble, and moſt of its Neck, ſeem'd to be poſ­ſeſſ'd by Air, ſince by its ſpring it was a­ble for ſo long to hinder the expell'd and ambient Liquor from regaining its former place. And it was remarkable, that juſt before we took the Glaſs bubble out of the other Glaſs, upon the application of a warm hand to the convex part of the bubble; the Impriſon'd ſubſtance readily dilated it ſelf like Air, and broke through the Liquor in divers bubbles, ſucceeding one another.

Having alſo another time try'd the like Experiment with a ſmall Viol, and with Nails diſſolv'd in Aquafortis, we found nothing incongruous to what we have now deliver'd. And this Circumſtance we obſerv'd, that the newly generated ſteams did not onely poſſeſs almoſt all the whole cavity of the Glaſs, but divers times without the aſſiſtance of the heat of my hand, broke away in large bubbles through the ambient Liquor into the o­pen Air: So that theſe Experiments with corroſive Liquors, ſeem'd manifeſt­ly enough to prove, though not that Air may be generated out of the Water, yet that in general air may be generated anew.

Laſtly, to the foregoing Arguments from Experience we might eaſily ſubjoyn the Authority of Ariſtotle, and of (his followers) the Schools who are known to have taught, that Air and Water being Symbolizing Elements (in the quality of moiſture) are eaſily tranſmutable into one another. But we ſhall rather to the fore­going Argument adde this, drawn from Reaſon, That if, as Leucippus, Democri­tus, Epieurus and others, follow'd by divers modern Naturaliſts, have taught, the difference of Bodies proceeds but from the various Magnitudes, Figures, Motions, and Textures of the ſmall parts they conſiſt of, (all the quali­ties that make them differ, being de­ducible from thence) there appeares no reaſon why the minute parts of Wa­ter, and other Bodies, may not be ſo agi­tated or connected as to deſerve the name of Air. For if we allow the Carteſian Hypotheſis, according to which, as we no­ted at the beginning of this Letter, the Air may conſiſt of any terrene or aqueous Corpuſcles, provided they be kept ſwim­ming in the interfluent Celeſtial Matter; it is obvious that Air may be as often ge­nerated, as Terreſtrial Particles minute enough to be carried up and down, by the Celeſtial Matter aſcend into the Atmo­ſphere. And if we will have the Air to be a congeries of little ſlender Springs, it ſeems not impoſſible, though it be diffi­cult, that the ſmall parts of divers Bo­dies may by a lucky concourſe of cauſes be ſo connected as to conſtitute ſuch little Springs, ſince (as we note in another Treatiſe) Water in the Plants it nouriſhes is uſually contriv'd into Springy Bodies, and even the bare alter'd poſition and con­nexion of the parts of a Body may ſuf­fice to give it a Spring that it had not be­fore, as may be ſeen in a thin and fiexible Plate of Silver; unto which, by ſome ſtroaks of a Hammer, you may give a Spring, and by onely heating it red hot you may make it again flexible as be­fore.

Theſe, My Lord, are ſome of the Conſiderations at preſent occurring to my thoughts, by which it may be made probable that Air may be generated a­new. And though it be not impoſſible to propoſe Objections againſt theſe, as well as againſt what has been repreſented in favor of the contrary Doctrine; yet having already almoſt tyr'd my ſelf, and I fear more then almoſt tyr'd Your Lord­ſhip with ſo troubleſome an Enquiry af­ter the Nature of bubbles, I ſhall wil­lingly leave Your Lordſhip to judge of the Arguments alledged on either ſide, and I ſhould ſcarce have ventur'd to enter­tain You ſo long concerning ſuch empty things as the Bubbles, which have occa­ſion'd all this Diſcourſe, but that I am willing to invite You to take notice with me of the obſcurity of things, or the dim­neſs of our created Intellects (which yet of late too many ſo far preſume upon, as either to Deny or Cenſure the Almighty and Omniſcient Creator himſelf) and to learn hence this Leſſon, That there are very many Things in Nature that we diſ­dainfully over-look as obvious or deſpi-cable, each of which would exerciſe our Underſtandings, if not poſe them too, if we would but attentively enough conſider it, and not ſuperficially contemplate, but attempt ſatisfactorily to explicate the na­ture of it.

SInce the writing of the twenty one and twenty ſecond Experiments (and not­withſtanding all that hath been on their occaſion deliver'd concerning bubbles) we made ſome further tryals in proſecution of the ſame inquiry whereto they were deſigned.

Experi­ment 23.

We choſe then, amongſt thoſe Glaſſes which Chymiſts are wont to call Philoſo­phical Eggs, one that containing about nine Ounces of Water, had a Neck of half an Inch in Diameter at the top, and as we gheſt, almoſt an Inch at the bot­tom; which breadth we pitch'd upon for a reaſon that will by and by appear: then filling it with common Water to the height of about a Foot and a half, ſo that the upper part remain'd empty, we ſhut it into the Receiver, and watch'd what would follow upon pumping, which pro-ved that a great part of the Air being drawn out, the bubbles began to diſcover themſelves at the bottom and ſides of the Glaſs; and increaſing, as the Air was more and more drawn away, they did from time to time aſcend copiouſly e­nough to the top of the Water, and there quickly break: but by reaſon that the wideneſs of the Glaſs allow'd them free paſſage through the Water, they did not appear as in the former Experiments to make it ſwell: The Water ſcarce ever ri­ſing at all above the mark affixt to its up­per ſurface when it was put in, and upon the return permitted to the outward Air, and conſequently the ſhrinking in of the remaining bubbles, the Water ſeem'd to have loſt of its firſt extent, by the avo­lation of the formerly interſperſ'd Air.

Being willing likewiſe to try whether diſtilled Water were by having been di­vided into minute parts, and then re-uni­ted, more or leſs diſpoſ'd to expand it ſelf then Water not diſtill'd: We took out of our Laboratory ſome careful­ly diſtill'd Rain-water, and put about two Ounces of it into a round Glaſs bubble with a very ſmall Neck (not ex­ceeding the ſixth part of an Inch in Dia­meter) which we fill'd half way to the top, and then convey'd it into the Recei­ver; the iſſue was, That though we drew out more then ordinary, yet there ap­pear'd not the leaſt intumeſcence of the Water, nor any aſcending bubbles.

But ſuſpecting that either the ſmall quantity of the water or the Figure of the Veſſel might have an intereſt in this odde Phænomenon, we took the lately mention'd Philoſophical Egge, and another not much differing from it; the former we fill'd up with diſtill'd Rain-water to the old mark, and into the latter we put a long Cylinder or Rod of ſolid Glaſs to ſtreighten the cavity of the Neck by al­moſt filling it up; and then pouring ſome diſtilled Water into that alſo, till it reach'd within ſome Fingers breadth of the top, the Eggs were let down into the Receiver. In this Experiment the Air was ſo far drawn forth before there ap­pear'd any bubble in either of the Glaſſes, that the diſparity betwixt this and com­mon water was manifeſt enough. But at length, when the Air was almoſt quite pump'd out, the bubbles began to diſ-cloſe themſelves, and to increaſe as the preſſure of the Air in the Receiver de­creaſ'd. But whereas in the firſt men­tion'd Philoſophical Egge the bubbles were very ſmall, and never able to ſwell the Water, that we took notice of, at all above the mark: In the other, whoſe Neck, as we lately ſaid, was ſtraightned, and their paſſage obſtructed, great num­bers of them, and bigger, faſtned them­ſelves to the lower end of the Glaſs ram­mer (if we may ſo call it) and gather'd in ſuch numbers between that and the ſides of the Neck, that the Water ſwell'd a­bout a Fingers breadth above the mark, though upon the admitting of the exter­nal Air it relapſ'd to the former mark, or rather fell ſomewhat below it. And al­though thereupon in the firſt nam'd Veſ­ſel all the bubbles preſently diſ-appear'd, yet in the other we obſerv'd, that divers remained faſtned to the lower part of the Glaſs rammer, and continued there ſome­what to our wonder, for above an hour after, but contracted in their Dimen­ſions.

Moreover, having ſuffered the Glaſſes to remain above twenty four hours in the Receiver, we afterwards repeated the Ex­periment, to try what change the exſucti­on of the external Air would produce in the Water, after the internal and latitant Air had (as is above recited) in great mea­ſure got away in bubbles, and whether or no the Water would by ſtanding re-admit any new particles of Air in the room of thoſe that had forſaken it. But though we exhauſted the Receiver very diligent­ly, yet we ſcarce ſaw a bubble in either of the Glaſſes; notwithſtanding which, we perceiv'd the Water to riſe about the breadth of a Barly-corn, or more, in the Neck of that Glaſs wherein the ſolid Cy­linder had been put; The Liquor in the other Glaſs not ſenſibly ſwelling.

And laſtly, upon the letting in of the Air, the Water in the ſtraightned Neck ſoon ſubſided to the mark above which it had ſwollen, which whether it ought to be aſcrib'd to the ſame ſmall expanſion of the parts of the Water it ſelf, or to the rarifaction of ſome yet latitant Air broken into ſuch ſmall particles, as to e­ſcape our obſervation, ſeems not eaſily determinable, without ſuch further tryals, as would perhaps prove tedious to be re­cited as well as to be made; though I was content to ſet down thoſe already men­tion'd, that it might appear how requi­ſite it is in nice Experiments to conſider variety of Circumſtances.

AFter having thus diſcover'd what ope­ration the exſuction of the ambient Air had upon Water, we thought good to try alſo what changes would happen in other Liquors upon the like taking off the preſſure of the external Air. We took then a Glaſs Egge, ſomewhat bigger then a Turkey Egge, which had a long Neck or Stem of about a 1/3 part of an Inch in Diameter; and filling it up with Sallet Oyl until it reach'd above half way to the top of the Neck, we incloſ'd it in the Re­ceiver together with common Water in a reſembling Veſſel, that we might the better compare together the operation of the exſuction of the Air upon thoſe two Liquors. The Pump being ſet a work there began to appear bubbles in the Oyl much ſooner then in the Water, and afterwards they alſo aſcended much more copiouſly in the former Liquor then the latter: Nay, and when by having quite tired the Pum­per, and almoſt our own patience, we gave over, the bubbles riſe almoſt (if not altogether) in as great numbers as ever, inſomuch as none of the various Liquors we tryed either before or ſince, ſeem'd to abound more with Aerial Parti­cles then did this Oyl. In which it was further remarkable, that between the time it was ſet into the Receiver, and that at which we could get ready to Pump, it ſub­ſided notably (by gheſs about half an Inch) below the mark it reach'd before it was put in.

Experi­ment 24.

After this expreſſ'd Oyl, we made tryal of a diſtill'd one, and for that purpoſe made choice of the common Oyl or Spi­rit (for in the Shops where it is ſold, the ſame Liquor is promiſcuouſly call'd by ei­ther name) of Turpentine; becauſe 'twas onely of that Chymical Oyl, we had a ſufficient quantity: which, being put in­to a ſmall Glaſs bubble with a ſlender Neck, ſo as to fill it to about two Inches from the top, did, upon the evacuating of the Receiver, preſent us with great ſtore of bubbles; moſt of which riſing from the bottom, expanded themſelves exceedingly in their aſcent, and made the Liquor in the Neck to ſwell ſo much by degrees, that at length it divers times ran over at the top: by which means, we were hindred from being able to diſcern upon the letting in of the Air, how much the ſubſidence of the Oyl below the firſt mark was due to the receſs of the bub­bles.

Having likewiſe a minde to try whe­ther as ſtrong a ſolution of Salt of Tartar in fair Water as could be made (we ha­ving then no Oyl of Tartar per deliqui­um at hand) though it be accounted, Quick-ſilver excepted, the heavieſt of Liquors would afford us any bubbles; we put in a Glaſs Egge full of it at the ſame time, with other Liquors, and found that they did long yield ſtore of bubbles be­fore any diſcovered themſelves in the Liquor of Tartar; and having purſued the Experiment, it appear'd, That of all the Liquors we made tryal of, this afford­ed the feweſt and the ſmalleſt Bubbles.

Spirit of Vinager being try'd after the ſame manner, exhibited a moderate num­ber of bubbles, but ſcarce any thing elſe worth the mentioning.

Nor could we in red Wine, try'd in a Glaſs Egge, take notice of any thing ve­ry obſervable. For though upon the ex­ſuction of the Air the bubbles aſcended in this Liquor, as it were in ſholes, and ſhifted places among themſelves in their aſcent; yet the Intumeſcence of the whole bulk of the Liquor was ſcarce at all ſenſible, the bubbles moſt commonly breaking very ſoon after their arrival at the top, where during their ſtay, they compoſ'd a kinde of ſhallow froth, which alone appear'd higher in the Neck of the Glaſs, then was the Wine when it was firſt let down. Neither yet did Milk, con­vey'd into our Pneumatical Veſſel, pre­ſent us with any thing memorable, ſave that (as it ſeem'd by reaſon of ſome un­ctuouſneſs of the Liquor) the bubbles not eaſily breaking at the top, and thruſt­ing up one another made the intumeſcence appear much greater then that of common Water.

We likewiſe convey'd Hens Eggs into the Receiver, but, after the exſuction of the Air, took them out whole again. That which invited us to put them in, was, That (as perhaps we mention in other Papers) we had among other Experiments of cold, made Eggs burſt, by freezing them within doors with Snow and Salt: The Ice, into which the aqueous parts of the Egge were turned by the cold, ſo diſtend-ing (probably by reaſon of the numerous bubbles wont to be obſervable in Ice) the outward parts of the Egge, that it uſually crack'd the ſhell, though the inner Mem­brane that involv'd the ſeveral Liquors of the Egge, becauſe it would ſtretch and yield, remain d unbroken, And here­upon we imagin'd that in our Engine it might appear whether or no there were any conſiderable Spring, either in any of the Liquors, or in any other more ſpiri­tuous ſubſtance included in the Egge.

We took alſo ſome Spirit of Urine, careleſly enough deflegmed, and put it in­to the ſame Glaſs (firſt carefully ſcowr'd and cleanſ'd) wherein we had put the Oyl­olive above mention'd: We took alſo an­other Glaſs, differing from a Glaſs Egge, onely in that its bottom was ſlat, and fill'd it up to about 2/3 of the Neck (which was wider then that of the Egge) with rectifi­ed Spirit of Wine.

We took alſo another Glaſs Egge, and having fill'd it with common Water till it reach'd to the middle of the Neck, we pour'd to it of the ſame Spirit of Wine, till it reach'd about an Inch higher.

Theſe three Glaſſes having marks ſet on them, over againſt the edges of the contain'd Liquors were put into the Re­ceiver, and that beginning to be evacua­ted, the bubbles in all the three Liquors began to appear. The mixture of the Spirit of Wine and Water diſcloſ'd a great ſtore of bubbles, eſpecially towards the top; but ſcarce afforded us any thing worth remem bring. The Spirit of Urine appear'd to ſwell near an Inch and an half above the mark; and beſides that, ſent forth ſtore of bubbles, which made a kinde of froth at the upper part of it. And above that ſpume there appear'd eight or ten great bubbles one above another, in a very decent order, each of them conſtitu­ting, as it were, a Cylinder of about half an Inch high, and as broad as the internal cavity of the Neck: So that all the upper part of the Neck (for theſe bubbles reach'd to the top) ſeem'd to be divided into al­moſt equal parts, by certain Diaphrag­mes, conſiſting of the coats of the bub­bles, whoſe edges appear'd like ſo many Rings ſuſpended one above another.

In the Spirit of Wine there did ariſe a great multitude of bubbles, even till wearineſs did make us give over the Ex­periment. And in theſe bubbles two or three things were remarkable; as firſt, That they aſcended with a very notable celerity: Next, That being arriv'd at the top, they made no ſtay there, and yet, notwithſtanding the great thinneſs and ſpitituouſneſs of the Liquor, did, before they broke, lift up the upper ſurface of it, and for a moment or two form thereof a thin film or skin which appear'd protu­berant above the reſt of the ſuperficies like a ſmall Hemiſphere. Thirdly, That they aſcended ſtraight up, whereas thoſe produc'd at the lower part of the Veſſel, containing the mixture of the Water and Spirit of Wine, aſcended with a waver­ing or wrigling motion, whereby they deſcrib'd an indented Line. Laſtly, It was obſervable in the Spirit of Wine (and we took notice of the like in the Oyl of Turpentine lately mention'd) that not onely the bubbles ſeem'd to riſe from cer­tain determinate places at the bottom of the Glaſs, but that in their aſcenſion they kept an almoſt equal diſtance from each other, and follow'd one another in a cer­tain order, whereby they ſeem'd part of ſmall Bracelets, conſiſting of equally lit­tle incontiguous Beads: the lower end of each Bracelet, being as it were, faſten'd to a certain point at the bottom of the Glaſs.