but be always ready to expand it selfe where it found least resistance so was it unable to fill the Receiver any more then until the Air within was reduc'd to the same measure of Compactness with that without We may also from our two already often mention'd Experiments further deduce that since Natures hatred of a Vacuum is but Metaphorical and Accidental being but a consequence or result of the pressure of the Air and of the Gravity and partly also of the Fluxility of some other bodies The power shee makes use of to hinder a Vacuum is not as we have else-where also noted any such boundless thing as men have been pleas'd to imagine And the reason why in the former Experiments mentioned in favour of the Plenists Bodies seem to forget their own Natures to shun a Vacuum seems to be but this That in the alleadged cases the weight of that Water that was either kept from falling or impell'd up was not great enough to surmount the pressure of the contiguous Air which if it had been the Water would have subsided though no Air could have succeeded For not to repeat that Experiment of Monsieur Paschal formerly mention'd to have been try'd in a Glass exceeding 32 Foot wherein the inverted Pipe being long enough to contain a competent weight of Water that Liquor freely ran out at the lower Orifice Not to mention this I say we saw in our nineteenth Experiment that when the pressure of the ambient Air was sufficiently weaken'd the Water would â—all out apace at the Orifice even of a short Pipe though the Air could not succeed into the room deserted by it And it were not amiss if tryal were made on the tops of very high Mountains to discover with what ease a Vacuum could be made near the confines of the Atmosphere where the Air is probably but light in comparison of what it is here below But our present three and thirtieth Experiment seems to manifest not onely that the power exercis'd by Nature to shun or replenâ—sh a Vacuum is limited but that it may be determin'd even to Pounds and Ounces Insomuch that we might say such a weight Nature will sustain or will lift up to resist a Vacuum in our Engine but if an Ounce more be added to that weight it will surmount Her so much magnifi'd detestation of Vacuities And thus My Lord our Experiments may not onely answer those of the Plenists but enable us to retort their Arguments against themselves since if that be true which they alleadge that when Water falls not down according to its nature in a Body wherein no Air can succeed to fill up the place it must leave the suspension of the Liquor is made Ne detur Vacuum as they speak it will follow that if the Water can be brought to subside in such a case that deserted space may be deem'd empty according to their own Doctrine especially since Nature as they would perswade us bestirs her self so mightily to keep it from being deserted I hope I shall not need to reminde Your Lordship that I have all this while been speaking of a Vacuum not in the strict and Philosophical sense but in that more obvious and familiar one that has been formerly declar'd And therefore I shall now proceed to observe in the last place that our 33d Experiment affords us a notable proof of the unheeded strength of that pressure which is sustain'd by the Corpuscles of what we call the free Air and presume to be uncompress'd For as fluid and yielding a Body as it is our Experiment teaches us That ev'n in our Climate and without any other compression then what is at least here below Natural or to speak more properly ordinary to it it bears so strongly upon the Bodies whereunto it is contiguous that a Cylinder of this free Air not exceeding three Inches in Diameter is able to raise and carry up a weight amounting to between sixteen and seventeen hundred Ounces I said even in our Climate Aere frigido existente taâ—dius moventur Automata quaÌ„ 〈◊〉 caâ—ido adeo quidem ut Automaton quod Belâ—â—e iâ— Noâ—a Zembla agentâ—s in aedibus 〈…〉 omnino 〈…〉 Varenius Geo Genevat lib. 111. Propo 7. pag. 648. because that is temperate enough and as far as my observations assist me to conjecture the Air in many other more Northern Countries may be much thicker and able to support a greater weight which is not to be doubted of if there be no mistake in what is Recorded concerning the Hollanâ—ers that were forc'd by the Ice to Winter in Nova Zembla namely That they found there so condens'd an Air that they could not make their Clock goe ev'n by a very great addition to the weights that were wont to move it I suppose Your Lordship will readily take notice that I might very easily have discoursed much more fully and accuratly then I have done against the common opinion touching Suction and touching natures hatred of a Vacuum But I was willing to keep my self to those considerations touching these matters that might be verifi'd by our Engine it self especially since as I said at first it would take up too much time to insist particularly upon all the Reflections that may be made even upon our two last Experiments And therefore passing to the next I shall leave it to your Lordship to consider how far these tryals of ours will either confirm or disfavor the new Doctrine of several eminent Naturalists who teach That in all motion there is necessarily a Circle of Bodies as they speak moving together and whether the Circles in such motion be an Accidental or Consequential thing or no. Experiment 34. T Is a known thing to those that are convesant in the Hydrostaticks That two Bodies which in the Air are of equal weight but of unequal bulk as Gold for instance and Iron being afterwards weighed in Water will lose their Aequilibrium upon the change of the ambient Body so that the Gold will sink lower then the Iron which by reason of its greater bulk has more Water to lift or displace that it may sink By Analogy to this Experiment it seem'd probable that if two weights did in our Engine ballance each other when the Glass was full of Air upon the exsuction of a great part of that Air so notable a change in the consistence of the ambient Body would make them lose their Aequilibrium But being desirous at the same time to make a tryal for a certain Design that needs not here be mention'd we took for one of our weights a dry Bladder strongly tyed at the Neck and about half fill'd with Air that being a weight both flight and that would expand it self in the evacuated Glass and fastning that to one part of our formerly mention'd exact ballance which turns with the 32d part of a Grain we put a Metalline counterpoise into the opposite Scale and so the two weights being brought to an
Enquiry touching Bubbles made with common and distill'd Water 182 The 24th Experiment wherein the inquiry is prosecuted with other Liquors as with Sallet Oyl Oyl of Turpentine a Solution of Tartar Spirit of Vinegar Red-wine Milk Hen's Eggs Spirit of Urine Spirit of Wine and Water Spirit of Wine 187 c. The wonderful expansion of the Spirit of Wine 194 The 25th Experiment touching the expansion and gravity of the Air under water 195 c. The 26th Experiment touching the Vibrations of a Pendulum 202 c. The 27th Experiment touching the propagation of sound And the Authors intention of trying some other Experiments for the further elucidation thereof 210 c. The 28 Experiment touching the sudden â—ruption of Bubbles from the water when the airs pressure was speedily remov'd 214 The 29 Experiment touching the cause of the ascent of Fumes and Vapors wherein 't is prov'd from the several motions which the Fumes of a strange smoaking Liquor of the Authors were observ'd to have in the Receiver upon the exsuction of the Air that the reason of their ascent proceeds from the gravity of the ambient air and not from any positive levity of their own 217 c. The 30 Experiment concerning the nature of a fluid Body illustrated by the example of smoak which in several circumstances seems very much to resemble the property of a fluid Body 224 c. A conjecture of the cause of the Suns undulation 228 The 31 Experiment concerning the Phaenomena of two flat Marbles exactly plain'd and wrought together and the true reason thereof 229. The Authors intention for the further prosecution thereof what hindred him the reason why the under Marble did not fal from the upper being onely conjoynd with Spirit of Wine when the Receiver was evacuated And a notable relation concerning the cohesion of flat Bodies 231 c. The 32 Experiment touching the forcible pressure of the Air against the outward superficies of a Valve fasten'd upon the stop-cock of the Receiver The Diameter of it and the weight it sustain'd 233 c. The 33 experiment touching the great pressure of the Air against the under superficies of the Sucker 236 c. what weight was requisite to depress it what weight it would lift and carry up with it 239 c. what improvement use there may be made of this experiment 242. A Discourse touching the nature of Suction proving that fuga vacui is not the adequate cause thereof 243 c. The 34th Experiment containing several attempts for the weighing of light Bodies in the exhausted Receiver 258 c. The 35th Experiment touching the cause of â—iltration and the rising of Water in Siphons 262 c. A relation of a new kinde of Siphon of the Authors upon the occasion of trying the Experiment lately observ'd by some French-men and further improv'd by himself and some conjectures touching the cause of the exhibited Phaenomena 267 c. The 36th Experiment touching the weighing of a parcel of Air in the exhausted Vessel and some other Observations for the explication thereof 272 c. An accidental Experiment tending to the further confirmation of the Authors Reflections upon the first Experiment with a digressive Observation noting the subtil penetrancy of some Spirits to exceed by far that of the Air 275 c. And some other Experiments to shew the difficulty of the ingress of the Air into the pores or holes of some bodies into which Water will readily insinuate it self 279 c. with a conjecture at the cause thereof 282. The Author returns to the prosecution of the inquiry after the gravity of the Air But first upon the occasion of the tenacity of a thin Bubble of Glass sets down his thoughts concerning the strange exuperancy of strength in Air agitated by heat above what the same has unagitated 283 c. And then proceeds to the examination of the weight of the Air by an Aeolipile and compares the result thereof with that of Mersennus 286. The Opinions and Experiments of divers Authors and some of his own touching the proportion of weight betwixt Water and Air are compar'd and examin'd by the Author 288. The result thereof 290. Mersennus his observation reconcil'd with that of the Author and the proportion between the gravity of Water and Air about London 291 c. After the recital of the Opinions of several Writers touching the proportion of gravity between Water and Quick silver the Author sets down his own tryals made several ways together with his conclusion therefrom 293 c. The use he makes of this inquiry for the ghessing at the height of the Atmosphere 297. What other Experiments are requisite to the determination thereof 299 c. The 37th Experiment touching the strange and odde Phaenomenon of the sudden flashes of light in the cavity of the Receiver the several circumstances and difficulties of it with some attempts towards the rendering at reason thereof 301 c. The Difficulty of so doing further shewn from the consideration of the various changes of Air which doe not immediatly fall under our senses 315. this last proposition prou'd by severall observations 316. The 38. Experiment touching the freezing of water 319. c. A problem concerning the great force wherewith a freezing Liquor extends its selfe propos'd upon the Consideration of divers admirable effects wrought thâ—reby 320 c. The 39. Experiment containing an inquisition after the temperature of the substance that remain'd in the cavity of the Receiver after the Air was well exhausted The relation of a Phaenomenon seeming to proceed from the swâ—lling of the Glass With an advertisement concerning the pliableness of Glass in small prices 322. c. The 40. Experiment touching the difficulty that occur'd in making tryall whether rarified Air were able to sustaine flying insects 326. c The 41. Experiment Exhibiting severall tryalls touching the respiration of divers sorts of animalls included in the Receiver 328 c. With a digression conteining some doubts touching respiration wherein are delivereâ— severall Experiments relating thereunto 335 c. The 42. Experiment touching the differing operation of corrosive Liquors in the emptied Receiver and in the open Air. 384 The 43. Experiment touching the spontaneous Ebullition of warm Liquors in the exhausted Receiver 388 The Conclusion 394 TO THE LORD OF DVNGARVAN My Honoured and Dear NEPHEW My Dear Lord REceiving in your last from Paris a desire that I would adde some more Experiments to those I formerly sent You over I could not be so much your Servant as I am without looking upon that Desire as a Command and consequently without thinking my self obliged to consider by what sort of Experiments it might the most acceptably be obey'd And at the same time perceiving by Letters from some other Ingenious Persons at Paris that several of the Virtuosi there were very intent upon the examination of the Interest of the Ayr in hindring the descent of the Quick-silver
much more or less then one of the twenty six divisions this Air took up By this means after a tryal or two we were inabled to convey to the top of the Glass a bubble of Air equal enough as to sight to one of those Divisions Then the open end of the Tube being put into a small Viol whose bottom was cover'd with Water about half an Inch high we included both Glasses into a small and slender Receiver and caused the Pump to be set awork The event was That at the first exsuction of the Air there appear'd not any expansion of the bubble comparable to what appear'd at the second and that upon a very few exsuctions the bubble reaching as low as the surface of the subjacent Water gave us cause to think that if our Pipe had not been broken it would have expanded it self much further Wherefore we took out the little Tube and found that besides the twenty six divisions formerly mention'd the Glass bubble and some part of the Pipe to which the divided Parchment did not reach amounted to six divisions more Whereby it appears that the air had taken up one and thirty times as much room as before and yet seem'd capable of a much greater expansion if the Glass would have permitted it Wherefore after the former manner we let in another bubble that by our guess was but half as big as the former and found that upon the exsuction of the Air from the Receiver this little bubble did not onely fill up the whole Tube but in part break through the subjacent Water in the Viol and thereby manifest it self to have possessed sixty and odde times its former room These two Experiments are mention'd to make way for the more easie belief of that which is now to follow Finding then that our Tube was too short to serve our turn we took a slender Quill of Glass which happen'd to be at hand though it were no so fit for our purpose as we could have wished in regard it was three or four times as big at one end as the other This Pipe which was thirty Inches long being Hermetically seal'd at the slender end was almost filled with Water and after the above-related manner a bubble was convey'd to the top of it and the open extream was put into a Viol that had a little fair Water at the bottom Then the Cover by means of a small hole purposely made in it for the Glass Pipe to stand out at was cemented on to the Receiver and the Pump being set awork after some exsuctions not onely the Air manifestly appear'd extended below the surface of the subjacent Water but one of the By-standers affirms that he saw some bubbles come out at the bottom of the. Pipe and break through the Water This done we left off Pumping and observ'd how at the unperceiv'd leaks of the Receiver the Air got in so fast that it very quickly impell'd up the Water to the top of the Tube excepting a little space whereinto that bubble was repuls'd which had so lately possess'd the whole Tube this Air at the slender end appear'd to be a Cylinder of â…š parts of an Inch in length but when the Pipe was taken out and turn'd upside down it appear'd at the other end inferior in bulk to a Pea. These things being thus done we took to make the Experiment the more exactly a small pair of Scales such as Gold-Smiths use to weigh Gold Coyn in and weighing the Tube and Water in it we found them to amount to one Ounce thirty Grains and an half Then we pourâ—d in as much Water as serv'd to fill up the Tube wherein before we had left as much space unfill'd up as was possess'd by the bubble and weighing again the Pipe and Water we found the weight increas'd onely by one Grain Lastly pouring out the Water and carefully freeing the Pipe from it which yet we could not perfectly doe we weighed the Glass alone and found it to want two Drachmes and thirty two Grains of its former weight So that the bubble of Air taking up the room but of one Grain in weight of Water it appear'd that the Air by its own 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 was so â—arified as to take up one hundred fifty two times as much room as it did before though it were then compress'd by nothing but the ordinary pressure of the contiguous Air. I know not whether it be requisite to take notice that this Experiment was made indeed in a moist Night but in a Room in whose Chimney there was burning a good Fire which did perhaps somewhat rarifie the Air of which the bubble consisted It has seem'd almost incredible which is related by the Industrious Mersennus That the Air by the violence of heat though as great as our Vessels can support without fusion can be so dilated as to take up seventy times as much room as before Wherefore because we were willing to have a confirmation of so strange a Phaenomenon we once more convey'd into the Tube a bubble of the bigness of the former and prosecuting the Experiment as before with the same Water we observed that the Air did manifestly stretch it self so far as to appear several times a good way below the surface of the Water in the Viol and that too with a surface very convex toward the bottom of the Pipe Nay the Pump being ply'd a little longer the Air did manifestly reach to that place where the bottom of the Tube lean'd upon the bottom of the Viol and seem'd to knock upon it and rebound from it Which Circumstances we adde partly that the Phaenomenon we have been relating may not be imputed to the bare subsiding of the Water that fill'd the Tube upon the taking off the pressure of the ambient Air. And partly also that it may appear that if our Experiments have not been as accurately made as with fitter Instruments might perhaps be possible yet the expansion of the Air is likely to be rather greater then lesser then we have made it Since the Air was able to press away the Water at the bottom of the Pipe though that were about two Inches below the surface of the Water that was then in the Viol and would have been at least as high in the Pipe if the Water had onely subsided and not been depressed So that it seems not unlikely that if the Experiment could be so made as that the expansion of the Air might not be resisted by the Neighboring Bodies it would yet inlarge its bounds and perhaps stretch it self to two hundred times its former bulk if not more However what we have now try'd will I hope suffice to hinder divers of the Phaenomena of our Engine from being distrusted Since in that part of the Atmosphere we live in that which we call the free Air and presume to be so uncompress'd is crouded into so very small a part of that space which if it were not hindred
either way the Terrestrial Steam may here and there considerably alter the gravity or pressure of the Atmosphere Your Lordship may also be pleased to remember That by our seventeenth Experiment it appear'd that as when the Air in the Receiver was expanded more then ordinarily the Quick-silver in the Tube did proportionably subside so when the Air in the same Receiver was a little more then ordinarily compress'd it did impell up the Quick-silver in the Tube above the wonted height of betwixt six and seven and twenty digits And if to these things we annex that for ought we can finde by tryals purposely made the degree of rarity or density of the Air shut up into our Receiver does not sensibly alter its temperature as to cold or heat It will not I hope appear absurd to conceive That since the Air included in the Tube could but very faintly hinder the ascent of the Quick-silver or press it downwards since too that included Air could scarce immediately receive any sensible alteration save either by heat or cold And since also that according to the bare density or rarity of the Air incumbent on the subjacent Quick-silver in the Vessel that in the Tube was impell'd more or less high such changes happening in the neighboring part of the outward Air either by the ascension of gross or copious exhalations or by any other cause of which there may be divers as were capable to make considerable alterations in the consistence of the Air as to rarity and density may be able proportionably to alter the heighth of the Quick-silver I rather say that such alterations may be then that they are the causes of our Phaenomenon because I think it sufficient if I have propos'd conjectures not altogether irrational about a new Mystery of Nature touching which the chief thing I pretend to is to give occasion to the Curious to inquire further into it then I have been yet able to do Experiment 19. THe same Reason that mov'd us to conclude that by the drawing of the Air out of the Receiver the Mercury would descend in a Tube shorter then six and twenty digits induc'd us also to expect that by the same means Water might be brought to subside in Glass Tubes of a moderate length though by the noble Experiment said to have been accurately made in France by Monsieur Paschal we are informed that a Tube of no less then about two and thirty Foot was found requisite to make the Experiment De Vacuo succeed with Water instead of Quick-silver so tall a Cylinder of that lighter Liquor being it seems requisite to equal the weight of a Mercurial Cylinder of six or seven and twenty digits and surmount the pressure of the Atmosphere We took then a Tube of Glass Hermetically seal'd at one end of about four foot in length and not very slender This at the open end we fill'd with common Water and then stopt that end till we had inverted the Tube and open'd it beneath the surface of a quantity of the like Water contain'd in a somewhat deep and slender Vessel This Vessel with the Tube in it was let down into the Receiver and the Receiver being clos'd up after the accustom'd manner the Pump was set awork As much of the event as concerns our present purpose was this That till a considerable part of the Air was drawn out of the Receiver the Tube continu'd top-full of Water as when it was put in it being requisite that a great part of the Air formerly contain'd in the Receiver should be drawn out to bring the remaining Air to an Aequilibrium with so short and light a Cylinder of Water But when once the Water began to fall in the Tube then each exsuction of Air made it descend a little lower though nothing near so much as the Quick-silver at the beginning did in the Experiment formerly mention'd Nor did there appear so much inequality in the spaces transmitted by the Water in its descent as there did in those observ'd in the â—all of the Quick-silver of which the cause will scarce seem abstruse to him that shall duly reflect upon what has been already deliver'd And whereas we drew down the Quick-silver in the Tube so far as to bring it within an Inch of the surface of the other Quick-silver into which it was to fall the lowest we were able to draw down the Water was by our conjecture to about a Foot or more above the surface of that in the Vessel of which I know not whether it will be needful to assign so obvious a cause as that though the little Air remaining in the Receiver could not hinder a Cylinder of above an Inch high of Quick-silver from subsiding yet it might very well be able by its pressure to countervail the weight of a Cylinder of a Foot long or more of a Liquor so much less ponderous then Quick-silver as Water is And in fine to conclude our Experiment when the Water was drawn down thus low we found that by letting in the outward Air it might be immediately impell'd up again to the higher parts of the Tube We will adde no more concerning this Experiment save that having try'd it in one of our small Receivers we observ'd That upon the first exsuction of the Air the Water did usually subside diveâ—s Inches and at the second exsuction fall down much lower subsiding sometimes near two Foot as also that upon the letting in of the Air from without the Water was impell'd up with very great celerity THat the Air has a notable Elastical power whencesoever that proceeds we have Experiment 20. I suppose abundantly evinc'd and it begins to be acknowledg'd by the eminentest Modern Naturalists But whether or no there be in Water so much as a languid one seems hitherto to have been scarce consider'd nor has been yet for ought I know determin'd either way by any Writer which invited us to make the following Experiment There was taken a great Glass-bubble with a long neck such as Chymists are wont to call a Philosophical Egg which being fill'd with common Water till the Liquor reach'd about a span above the bubble and a piece of Paper being there pasted on was put unstop'd into the Receiver and then the Air was suck'd out after the wonted manner The event was this That a considerable part of the Air pent up in the Receiver was drawn out before we discern'd any expansion of the Water but continuing the labor of pumping the Water manifestly began to ascend in the stem of the Glass and divers bubbles loosening themselves from the lower parts of the Vessel made their way through the Body of the Water to the top of it and there brake into the Receiver And after the Water once appear'd to swell then at each time the Stop-cock was turn'd to let out the air from the Receiver into the Pump the Water in the Neck of the Glass did suddenly rise about the breadth of
a Barly-corn in the Neck of the Glass and so attain'd by degrees to a considerable height above the mark formerly mention'd And at length to make the expansion of the Water more evident the outward Air was suddenly let in and the Water immediately subsided and deserted all the space it had newly gain'd in the Glass And on this occasion it will not perhaps be amiss to acquaint Your Lordship here though we have already mention'd it in another Paper to another purpose with another Expedient that we made use of two or three years ago to try whether or no Water had a Spring in it About that time then That Great and Learned Promoter of Experimental Philosophy Dr. Wilkins doing me the Honor to come himself and bring some of his inquisitive Friends to my Lodging we there had in readiness a round and hollow Vessel of Pewter great enough to contain two pounds of Water and exactly close every where but at one little hole where it was to be fill'd then partly by sucking out the Air and partly by injecting Water with a Syringe it was not without some difficulty fill'd up to the top and that hole being plac'd directly upwards there was a little more Water leisurely forc'd in by the Syringe Upon which though the Vessel were permitted to rest and the hole kept in its former posture yet the compress'd Water leisurely swell'd above the Orifice of the hole and divers drops ran over along the sides of the Vessel After this we caus'd a skilful Pewterer who had made the Globe to close it up in our presence with Soder so exquisitely that none suspected there was any thing left in it besides Water And lastly the Vessel thus soder'd up was warily and often struck in divers places with a Wooden Mallet and thereby was manifestly compress'd whereby the inclosed Water was crouded into less room then it had before And thereupon when we took a Needle and with it and the Mallet perforated the Vessel and drew out the Needle again the Water but in a very slender Stream was suddenly thrown after it into the Air to the height of two or three Feet As for the other Phaenomena of this Experiment since they belong not to our present purpose and are partly mention'd in another of our Papers we shall instead of recording them here give this Advertisement That as evidently as this Experiment and that made in our Receiver seem to prove a power in the Water to expand and restore it self after compression yet for a reason to be met with ere long I judged it not safe to infer that Conclusion from these Premises till I had made some of the following tryals to the mention of which I will therefore hasten TO discover whether the Expansion of the Water really proceeded from an Elastical power in the parts of the Water it self Experiment 21. we thought it requisite to try two things The one Whether or no the Atmosphere gravitates upon Bodies under Water and the other Whether in case it do gravitate the Intumescence of the Water may not be ascribed to some substance subtler then it self residing in it In order to the satisfying my self about the first of these I intended to let down into the Receiver a Vessel of Water wherein should be immers'd a very small oyl'd Bladder almost devoid of Air but strongly ty'd up at the Neck with a string and detain'd a little under Water by such a weight fasten'd to that string as should just be able to keep the Bladder from swimming and no more For I suppos'd that if when all things were thus order'd the Receiver were empty'd in case there were any such pressure of the Atmosphere upon Water as I was inclin'd to believe the Air within the Bladder being upon the exsuction of the Air within the Receiver freed from that pressure and being press'd onely by the small weight of the incumbent Water would considerably expand it self but whil'st we were preparing Bladders for this Experiment there occurd an easie way for the making at once both the Discoveries I desir'd We took then a Glass Viol containing by ghess a pound and some ounces of Water this we fill'd top full and then we put into the Neck of it a Glass Pipe a pretty deal bigger then a Goose Quill open at both ends and of divers Inches in length One end of this Pipe was so put into the Neck of the Viol as to reach a little below it and then was carefully cemented thereto that no Air might get into the Viol nor no Water get out of it otherwise then through the Pipe and then the Pipe being warily fill'd about half way up to the top with more Water and a mark being pasted over against the upper surface of the Liquor the Viol thus fitted with the Pipe was by strings let down into the Receiver and according to the wonted manner exquisitely clos'd up in it This done we began to Pump out the Air and when a pretty quantity of it had been drawn away the Water in the Pipe began to rise higher in the Pipe at the sides of which some little bubbles discover'd themselves After a little while longer the Water still swelling there appear'd at the bottom of the Pipe a bubble about the bigness of a small Pea which ascending through the Pipe to the top of the Water staid there awhile and then broke but the Pump being nimbly ply'd the expansion of the Water so encreas'd that quickly getting up to the top of the Pipe some drops of it began to run down along the out-side of it which oblig'd us to forbear pumping awhile and give the Water leave to subside within less then two Inches of the bottom of the Pipe After this the Pump being again set at work the bubbles began to ascend from the bottom of the Pipe being not all of a size but yet so big that estimating one with another they appear'd to be of the size of the smaller sort of Peas and of these we reckon'd about sixty which came up one after another besides store of smaller ones of which we made no reckoning And at length growing weary of reckoning and pumping too because we found that in spight of all our pains and industry some undiscern'd Leak or other in the Receiver hinder'd us from being able to empty it altogether we thought fit to desist for that time After tryal made of what operation the external Air being let in upon the expanded Water would have and accordingly turning the Key to let in the Air we saw as we expected that the Water in the Pipe in a moment fell down almost to the bottom of it 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 't is 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 external 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 endowâ—d 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 Experiment 22. 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 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 Phaenomenon 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 Vacuo with 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 found 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 Quick-silver 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 mentionâ—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
the juncture there was setled a round whitish Spot or two which at first we thought might be some stain upon the Glass but after finding it to be in divers Qualities like the Oyl and Salt of the Concrete we were Distilling we began to suspect that the most subtle and fugitive parts of the impetuously ascending Steams had penetrated the substance as they speak of the Glass and by the cold of the ambient Air were condens'd on the surface of it And though we were very backward to credit this suspition and therefore call'd in an Ingenious Person or two both to assist us in the Observation and have Witness of its event we continued a while longer to watch the escape of such unctuous Fumes and upon the whole matter unanimously concluded That all things consider'd the subtle parts of the distill'd matter being violently agitated by the excessive heat had pass'd through the Pores of the Glass widen'd by the same heat But this having never happen'd but once in any of the Distillations we have either made or seen though these be not a few it is much more reasonable to suppose that the perviousness of our Receiver to a Body much more subtle then Air proceeded partly from the looser Texture of that particular parcel of Glass the Receiver was made of for Experience has taught us that all Glass is not of the same compactness and solidity and partly from the enormous heat which together with the vehement agitation of the penetrant Spirits open'd the Pores of the Glass then to imagine that such a substance as Air should be able to permeate the Body of Glass contrary to the testimony of a thousand Chymical and Mechanical Experiments and of many of those made in our Engine especially that newly recited Nay by our fifth Experiment it appears that a thin Bladder will not at its Pores give passage even to rarified Air. And on this occasion we will annex an Experiment which has made some of those we have acquainted with it doubt whether the Corpuscles of the Air be not lesse subtle then those of Water But without examining here the reasonablenesse of that doubt we will proceed to recite the Experiment it self which seems to teach That though Air when sufficiently compress'd may perchance get entrance into narrower holes and crannies then Water yet unless the Air be forc'd in at such very little holes it will not get in at them though they may be big enough to let Water pass through them The Experiment then was this I took a fair Glass Siphon the lower end o◠whose longest Leg was drawn by degrees to such a slenderness that the Orifice at which the Water was to fall out would hardly admit a very small Pin This Siphon being inverted the matter was so order'd that a little Bubble of Air was intercepted in the slenderest part of the Siphon betwixt the little hole newly mention'd and the incumbent Water upon which it came to pass that the Air being not to be forc'd through so narrow a passage by so light a Cylinder of Water though amounting to the length of divers Inches as lean'd upon it hinder'd the further Efflux of the Water as long as I pleas'd to let it stay in that narrow place whereas when by blowing a little at the wider end of the Siphon that little parcel of Air was forc'd out with some Water the remaining Water that before continu'd suspended began freely to drop down again as formerly And if you take a Glass Pipe whether it be in the form of a Siphon or no that being for the most part of the thickness of a Mans Finger is yet towards one end so slender as to terminate in a hole almost as small as a Horse-hair and if you fill this Pipe with Water you will finde that Liquor to drop down freely enough thorow the slender Extream But if you then invert the Pipe you will finde that the Air will not easily get in at the same hole through which the Water pass'd For in the sharp end of the Pipe some Inches of Water will remain suspended which 't is probable would not happen if the Air could get in to succeed it since if the hole were a little wider the Water would immediatly subside And though it be true that if the Pipe be of the length of many Inches a great part of the Water will run down at the wider Orifice yet that seems to happen for some other reason then because the Air succeeds it at the upper and narrow Orifice since all the slender part of the Pipe and perhaps some Inches more will continue full of Water And on this occasion I remember that whereas it appears by our fifth Experiment That the Aërial Corpuscles except perhaps some that are extraordinarily fine will not passe thorow the Pores of a Lambs Bladder yet Particles of Water will as we have long since observ'd and as may be easily try'd by very closely tying a little Alcalizate Salt we us'd the Calx of Tartar made with Nitre in a fine Bladder and dipping the lower end of the Bladder in Water for if you hold it there for a competent while you will finde that there will strain thorow the Pores of the Bladder Water enough to dissolve the Salt into a Liquor But I see I am slipt into a Digression wherefore I will not examine whether the Experiment I have related proceeded from hence That the springy Texture of the Corpuscles of the Air makes them less apt to yield and accommodate themselves easily to the narrow Pores o◠Bodies then the more flexible Particles of Water or whether it may more probabiy be ascrib'd to some other Cause Nor will I stay to consider how far we may hence be assisted to ghess at the cause of the ascension of Water in the slender Pipes and Siphons formerly mention'd but will return to our Bubble and take notice That we thought fit also to endeavor to measure the capacity of the Bubble we had made use of by filling it with Water that we might the better know how much Water answered in weight to ¾ of a Grain of Air but notwithstanding all the diligence that was used to preserve so brittle a Vessel it broke before we could perfect what we were about and we were not then provided of another Bubble fit for our turn The haste I was in My Lord when I sent away the last Sheet made me forget to take notice to you of a Problem that occurr'd to my thoughts upon the occasion of the slow breaking of the Glass Bubble in our evacuated Receiver For it may seem strange since by our sixth Experiment it appears that the Air when permitted will by its own internal Spring expand it selfe twice as much as Mersennus was able to expand it by the heat even of a candent Aeolipile Yet the Elater of the Air was scarce able to break a very thin Glass Bubble and utterly unable to break one
it contained amounting to one and twenty ounces and an halfe and as much Air as was requisite to fill it weighing eleven graines the proportion in gravity of Air to Water of the same bulk will be as one to 938. And though we could not fill the Aeolipile with water so exactly as we would yet in regard we could not either as perfectly as we would drive the Air out of it by heat we think the proportion may well enough hold but those that are delighted with round numbers as the phrase is will not be much mistaken if they reckon water to be neere a thousand times heavier than Air. And for further proof that we have made the proportion betwixt these two bodies rather greater then lesser then indeed it is and also to confirme our former observation of the weight of the Air we will adde That having another time put some Water into the Aeolipile before we set it on the fire that the copious vapours of the rarefied liquor might the better drive out the Air we found upon tryall carefully made that when the Aeolipile was refrigerated and the included vapours were by the cold turned againe into water which could not have happen'd to the Air that the preceeding Steams expell'd the Air when it was let in increas'd the weight of the Aeolipile as much as before namely Eleven Grains though there were already in it twelve Drachmes and a half besides a couple of Grains of Water which remain'd of that we had formerly put into it to drive out the Air. Mersennus indeed tells us that by his account Air is in weight to Water as 1 to 1356. And adds that we may without any danger believe that the gravity of Water to that of Air of a like bulk is not less then of 1300 to 1. And consequently that the quantity of Air to a quantity of Water equiponderant thereto is as 1300 to 1. But why we should relinquish our own carefully repeated tryals I see not Yet I am unwilling to reject those of so accurate and useful a Writer And therefore shall propose a way of reconciling our differing Observations by presenting that the discrepance between them may probably arise from the differing consistence of the Air at London and at Paris For our Air being more cold and moist then that which Your Lordship now breaths may be suppos'd also to be a fourth or fifth part more heavy I leave it to be consider'd whether it be of any moment that our Observations were made in the midst of Winter whereas his were perhaps made in some warmer time of the Year But I think it were not amiss that by the method formerly propos'd the gravity of the Air were observ'd both in several Countries and in the same Country in the several Seasons of the Year and differing Temperatures of the Weather And I would give something of value to know the weight of such an Aeolipile as ours full of air in the midst of Winter in Nova Zembla if that be true which we formerly took notice of namely That the Hollanders who Wintered there found that Air so thick that their Clock would not go If Your Lordship should now ask me if I could not by the help of these and our other Observations decide the Controversies of our Modern Mathematicians about the height of the Air or Atmosphere by determining how high it doth indeed reach I should answer That though it seems easie enough to shew that divers Famous and Applauded Writers have been mistaken in assigning the heigth of the Atmosphere Yet it seems very difficult precisely to define of what height it is And because we have hitherto but lightly touch'd upon a matter of such importance we presume it wil not be thought impertinent upon this occasion to annex something towards the Elucidation of it What we have already try'd and newly set down allows us to take it for granted that at least about London the proportion of gravity betwixt Water and Air of equal bulk is as of a thousand to one The next thing therefore that we are to enquire after in order to our present design is the difference in weight betwixt Water and Quick-silver And though this hath been defin'd already by the Illustrious Verulam and some other inquisitive Persons that have compar'd the weight of several Bodies and cast their Observations into Tables yet we shall not scruple to annex our own tryals about it Partly because we finde Authors considerably to dis-agree partly because we us'd exacter Scales and a somewhat more wary method then others seem to have done And partly also because having prosecuted our inquiry by two or three several ways the small difference between the events may assure us that we were not much mistaken We took then a Glass Pipe of the form of an inverted Siphon whose shape is delineated in the sixteenth Figure And pouring into it a quantity of Quick silver we held it so that the superficies of the Liquor both in the longer and shorter leg lay in a Horizontal Line denoted in the Scheme by the prick'd Line EF then pouring Water into the longer Leg of the Siphon till that was almost fill'd we observ'd the surface of the Quick-silver in that leg to be by the weight of the Water depress'd as from E to B and in the shorter leg to be as much impell'd upward as from F to G Whereupon having formerly stuck marks as well at the point B as at the opposite point D we measurâ—d both the distance DC to have the height of the Cylinder of Quick-silver which was raisâ—d above the Point D level with the surface of the Quick-silver in the other leg by the weight of the Water and the distance BA which gave us the height of the Cylinder of Water So that the distance D C amounting to 2 â—â— â—â— Inches and the height of the Water amounting 30 45 5â— Inches and the whole numbers on both sides which the annexed Fractions being reduc'd to improper Fractions of the same denomination the proportion appear'd to be the denominators beng left out as equal on both sides as 121 to 1665 or by reduction as one to 13 â—â— â—â— Besides this unusual way of determining the gravity of some things we measur'd the proportion betwixt Quick-silver and Water by the help of so exact a ballance as looses its Aequilibrium by the hundredth part of a Grain But because there is wont to be committed an oversight in weighing Quick-silver and Water especially if the Orifice of the Vessel wherein they are put be any thing wide in regard that men heed not that the surface of Water in Vessels will be concave but that of Quick-silver notably convex or protuberant To avoid this usual oversight I say we made use of a glass bubble blown very thin at the Flame of a Lamp that it might not be too heavy for the Ballance and terminating in a very slender neck wherein the concavity or convexity
of a Liquor could not be considerable This Glass weighing 23 1 â— Grains we fill'd almost with Quick-silver and fastning a mark over against the middle of the protuberant Superficies as near as our Eyes could judge we found that the Quick-silver alone weighed 299 â— 3â— Grains Then the Quick-silver being pour'd out and the same Glass being fill'd as full of common Water we found the Liquor to weigh 21 7 8 Grains Whereby it appear'd that the weight of Water to Quick-silver is as one to 13 â—9 2â— Though our Illustrious Verulam questionless not for want of Judgement or Care but of exact Instruments makes the proportion betwixt those two Liquors to be greater then of 1 to 17. And to adde that upon the by since Quick-silver and well rectified Spirit of Wine are how justly I say not accounted the one the heaviest and the other the lightest of Liquors we thought to fill in the same Glass and with the same Scales to observe the difference betwixt them which we found to be as of 1 to 16 64â— â—0â—4 whereby it appear'd That the difference betwixt Spirit of Wine that may be made to burn all away such as was ours and common Water is as betwixt 1 and 1 â—â— â—â—â— We might here take occasion to admire that though Water as appear'd by the Experiment formerly mention'd of the Pewter Vessel seems not capable of â—ny considerable condensation and seems not to have interspers'd in it any store of Air yet Quick-silver of no greater bulk then Water should weigh near fourteen times as much But having onely pointed at this as a thing worthy of consideration we will proceed in our inquiry after the heigth of the Atmosphere And to avoid the trouble of Fractions we will assume that Quick-silver is fourteen times as heavy as Water since it wants so little of being so Wherefore having now given us the proportion of Air to Water and Water to Quick-silver it will be very easie to finde the proportion betwixt Air and Quick-silver in case we will suppose the Atmosphere to be uniformly of such a consistence as the Air we weighed here below For since our Engine hath sufficiently manifested that 't is the Aequilibrium with the external Air that in the Torricellian Experiment keeps the Quick-silver from subsiding And since by our accurate Experiment formerly mention'd it appears that a Cylinder of Mercury able to ballance a Cylinder of the whole Atmosphere amounted to near about thirty Inches and since consequently we may assume the proportion of Quick-silver to Air to be as fourteen thousand to one it will follow that a Cylinder of Air capable to maintain an Aequilibrium with a Mercurial Cylinder of two Foot and an half in height must amount to 35000 Feet of our English Measure and consequently reckoning five Foot to a Geometrical Pace and one thousand such Paces to a Mile to seven full Miles But this as we lately intimated proceeds upon the supposition that the Air is every where of the same consistence that we found it near the surface of the Earth but that cannot with any safety be concluded not onely for the reason I finde to have been taken notice of by the Antients and thus exprest in Seneca Omnis Aër says he quo propior est terris hoc crassior Senec Nat quest lib. 4. cap. 10. quemadmodum in aqua in omni humore faex ima est ita in Aëre spississima quaeque desidunt but much more because the springy Texture of the Aërial Corpuscles makes them capable of a very great compression which the weight of the incumbent part of the Atmosphere is very sufficient to give those that be undermost and near the surface of the Earth And if we recall to minde those former Experiments whereby we have manifested That Air much rarefied without heat may easily admit a further rarefaction from heat and that the Air even without being expanded by heat is capable of being rarefied to above one hundred and fifty times the extent it usually possesses here below How can it be demonstrated that the Atmosphere may not for ought we know or at least for ought can be determin'd by our Statical and Mechanical Experiments rise to the height of Five and twenty German Leagues if not of some hundred of common Miles And this conjecture it self may appear very injurious to the height whereunto Exhalations may ascend Ricciol Alma Nov Tom 2. lib. 10 sect 6. prop. 50. Ex magnan lib. 1. Perspective horarie prop 38. if we will allow that there was no mistake in that strange Observation made at Tolous in a clear Night in August by the diligent Mathematician Emanuel Magnan and thus Recorded by Ricciolus for I have not at hand the Authors own Book Vidit says he ab hor a undecima post meridiem usque ad mediam noctem Lunâ infra horizontem posit â nubeculam quandam lucidam prope Meridianum fere usque ad Zenith diffusam quae consideratis omnibus non poterat nisi à sole illuminari ideoque altior esse debuit tota umbra terrae Addit continues Ricciolus simile quid evenisse Michaeli Angelo Riccio apud Sabinos versanti nempe viro in Mathesi eruditissimo Various Observations made at the feet tops and interjacent parts of high Mountains might perchance somewhat assist us to make an estimate in what proportion if in any certain one the higher Air is thicker then the lower and ghess at the dis-form consistence as to laxity and compactness of the Air at several distances from us And if the difficulties about the refractions of the Celestial Lights were satisfactorily determin'd that might also much conduce to the placing due limits to the Atmosphere whose Dimensions those Observations about Refractions seem hitherto much to contract But for the present we dare not pronounce any thing peremptorily conâ—cerning the height of it but leave it to further inquiry contenting our selves to have manifested the mistake of divers eminent Modern Writers who will not allow the Atmosphere to exceed above two or three Miles in height as the Famous Kepler will not the Aër refractivus and to have rendred a reason why in the mention we made in the Notes upon the first Experiment touching the height of the Atmosphere we scrupled not to speak of it as if it might be many Miles high WE will now proceed to recite a Phaenomenon Experiment 37. which though made amongst the first we thought fit not to mention till after many others that we might have the opportunity to observe as many Circumstances of it as we could and so present Your Lordship at once most of what we at several times have taken notice of concerning so odde a Phaenomenon Our Engine had not been long finish'd when at the first leasure we could steal from our occasions to make tryal of it we caus'd the Air to be pump'd out of the Receiver and whil'st I was busied in entertaining a Learned
former position may be Mechanically explicated Yet I must confess that to determine whether the motion of Restitution in Bodies proceed from this That the parts of a Body of a peculiar Structure are put into motion by the bending of the spring or from the endeavor of some subtle ambient Body whose passage may be oppos'd or obstructed or else it 's pressure unequally resisted by reason of the new shape or magnitude which the bending of a Spring may give the Pores of it To determine this I say seems to me a matter of more difficulty then at first sight one would easily imagine it Wherefore I shall decline medling with a subject which is much more hard to be explicated then necessary to be so by him whose business it is not in this Letter to assign the adequate cause of the Spring of the Air but onely to manifest That the Air has a Spring and to relate some of its effects I know not whether I need annex that though either of the above-mention'd Hypotheses and perhaps some others may afford us an account plausible enough of the Air-spring yet I doubt whether any of them gives us a sufficient account of its Nature And of this doubt I might here mention some Reasons but that peradventure I may God permitting have a fitter occasion to say something of it elsewhere And therefore I should now proceed to the next Experiment but that I think it requisite first to suggest to your Lordship what comes into my thoughts by way of Answer to a plausible Objection which I foresee you may make against our propos'd Doctrine touching the Spring of the Air. For it may be alleadged that though the Air were granted to consist of Springy Particles if I may so speak yet thereby we could onely give an account of the Dilatation of the Air in Wine-Guns and other pneumatical Engines wherein the Air has been compress'd and its Springs violently bent by an apparent externall force upon the removall of which 't is no wonder that the Air should by the motion of restitution expand it self till it have recovered its more natural dimensions whereas in our above mentioned first Experiment and in almost all others tryable in our Engine it appears not that any compression of the Air preceded its spontaneous Dilatation or Expansion of it self To remove this difficulty I must desire Your Lordship to take notice that of whatever nature the Air very remote from the Earth may be and whatever the Schools may confidently teach to the contrary yet we have divers Experiments to evince that the Atmosphere we live in is not otherwise then comparatively to more ponderous Bodies light but heavy And did not their gravity hinder them it appears not why the steams of the Terraqueous Globe of which our Air in great part consists should not rise much higher then the Refraction of the Sun and other Stars give men ground to think that the Atmosphere even in the judgement of those Recent Astronomers who seem willing to enlarge its bounds as much as they dare does reach But lest you should expect my seconding this Reason by Experience and lest you should object That most of the Experimēts that have been propos'd to prove the gravity of the Air have been either barely propos'd or perhaps not accuratly try'd I am content before I pass further to mention here That I found a dry lambs-bladder containing near about two thirds of a pint and compress'd by a packthred tyed about it to loose a grain and the eighth part of a grain of its former weight by the recess of the Air upon my having prickt it And this with a pair of Scales which when the full Bladder and the correspondent weight were in it would manifestly turn either way with the 32 part of a grain And if it be further objected That the Air in the Bladder was violently compress'd by the Pack-thred and the sides of the Bladder we might probably to wave prolix answers be furnish'd with a Reply by setting down the differing weight of our Receiver when empty'd and when full of uncompress'd Air if we could here procure scales fit for so nice an experiment since we are informed that in the German Experiment commended at the beginning of this Letter the Ingenious Tryers of it found That their Glass Vessel of the capacity of 32 measures was lighter when the Air had been drawn out of it then before by no less then one ounce and 1 10 that is an ounce and very near a third But of the gravity of the Air we may elsewhere have occasion to make further mention Taking it then for granted that the Air is not devoid of weight it will not be uneasie to conceive that that part of the Atmosphere wherein we live being the lower part of it the Corpuscles that compose it are very much compress'd by the weight of all those of the like nature that are directly over them that is of all the Particles of Air that being pil'd up upon them reach to the top of the Atmosphere And though the height of this Atmosphere according to the famous Kepler and some others scarce exceeds eight common miles yet other eminent and later Astronomers would promote the confines of the Atmosphere to exceed six or seven times that number of miles And the diligent and learned Riviolo makes it probable that the Atmosphere may at least in divers places be at least 50 miles high So that according to a moderate estimate of the thickness of the Atmosphere we may well suppose that a Column of Air of many miles in height leaning upon some springy Corpuscles of Air here below may have weight enough to bend their little springs and keep them bent As to resume our former comparison if there were fleeces of Wooll pil'd up to a mountainous height upon one another the Hairs that compose the lowermost locks which support the rest would by the weight of all the Wool above them be as well strongly compressed as if a man should squeeze them together in his hands or imploy any such other moderate force to compress them So that we need not wonder that upon the taking off the incumbent Air from any parcel of the Atmosphere here below the Corpuscles whereof that undermost Air consists should display themselves and take up more room then before And if it be objected That in Water the weight of the upper and of the lower part is the same I answer That besides that it may be well doubted whether the observation by reason of the great difficulty have been exactly made there is a manifest disparity betwixt the Air and Water For I have not found that upon an Experiment purposely made and in another Treatise Recorded that Water will suffer any considerable compression whereas we may observe in Wind-Guns to mention now no other Engines that the Air will suffer it self to be crouded into a comparatively very little room in so much that
a very diligent Examiner of the Phaenomena of Wind-Guns would have us believe that in one of them by condensation he reduc'd the Air into a space at least eight times narrower then it before possest And to this if we adde a noble Phaenomenon of the Experiment De Vacuo these things put together may for the present suffice to countenance our Doctrine For that noble Experimenter Monsieur Pascal the Son had the commendable Curiosity to cause the Torricellian Experiment to be try'd at the foot about the middle and at the top of that high Mountain in Auvergne if I mistake not commonly call'd Le Puy de Domme whereby it was found That the Mercury in the Tube fell down lower about three inches at the top of the Mountain then at the bottom And a Learned Man a while since inform'd me That a great Virtuoso friend to us both has with not unlike success tryed the same Experiment in the lower and upper parts of a Mountain in the West of England Of which the reason seems manifestly enough to be this That upon the tops of high Mountains the Air which bears against the restagnant Quick-silver is less press'd by the less ponderous incumbent Air and consequently is not able totally to hinder the descent of so tall and heavy a Cylinder of Quick-silver as at the bottom of such Mountains did but maintain an Aequilibrium with the incumbent Atmosphere And if it be yet further Objected against what hath been propos'd touching the compactness and pressure of the Inferior Air That we finde this very Air to yield readily to the motion of little Flies and even to that of Feathers and such other light and weak Bodies which seems to argue that the particles of our Air are not so compress'd as we have represented them especially since by our former Experiment it appears that the Air readily dilated it self downward from the Receiver into the Pump when 't is plain that it is not the incumbent Atmosphere but onely the subjacent Air in the brass Cylinder that has been remov'd If this I say be objected we may reply That when a man squeezes a Fleece of Wool in his hand he may feel that the Wool incessantly bears against his hand as that which hinders the hairs it consists of to recover their former and more natural extent So each parcel of the Air about the Earth does constantly endeavour to thrust away all those contiguous Bodies whether Aërial or more gross that keep them bent and hinder the expansion of its parts which will dilate themselves or flie abroad towards that part whether upwards or downwards where they finde their attempted Dilatation of themselves less resisted by the neihgboring Bodies Thus the Corpuscles of that Air we have been all this while speaking of being unable by reason of their weight to ascend above the Convexity of the Atmosphere and by reason of the resistance of the surface of the Earth and Water to fall down lower they are forced by their own gravity and this resistance to expand and diffuse themselves about the Terrestial Globe whereby it comes to pass that they must as well press the contiguous Corpuscles of Air that on either side oppose their Dilatation as they must press upon the surface of the Earth and as it were recoyling thence endeavor to thrust away those upper particles of Air that lean upon them And as for the easie yielding of the Air to the Bodies that move in it if we consider that the Corpuscles whereof it consists though of a springy nature are yet so very small as to make up which 't is manifest they doe a fluid Body it will not be difficult to conceive that in the Air as in other Bodies that are fluid the little Bodies it consists of are in an almost restless motion whereby they become as we have more fully discoursed in another Treatise very much disposed to yield to other Bodies In a Discourse touching fluidity and firmness or easie to be displac'd by them and that the same Corpuscles are likewise so variously mov'd as they are intire Corpuscles that if some strive to push a Body plac'd among them towards the right hand for instance others whose motion has an opposite determination as strongly thrust the same Body towards the left whereby neither of them proves able to move it out of its place the pressure on all hands being reduced as it were to an Aequilibrium so that the Corpuscles of the Air must be as well sometimes considered under the notion of little Springs which remaining bent are in their entire bulk transported from place to place as under the notion of Springs displaying themselves whose parts flie abroad whilst as to their entire bulk they scarce change place As the two ends of a Bow shot off fly from one another whereas the Bow it self may be held fast in the Archers hand and that it is the equal pressure of the Air on all sides upon the Bodies that are in it which causes the easie Cession of its parts may be argu'd from hence That if by the help of our Engine the Air be but in great part though not totally drawn away from one side of a Body without being drawn away from the other he that shall think to move that Body too and fro as easily as before will finde himself much mistaken In verification of which we will to divert your Lordship a little mention here a Phaenomenon of our Engine which even to divers ingenious persons has at first sight seem'd very wonderful THe thing that is wont to be admired Experiment 2. and which may pass for our second Experiment is this That if when the Receiver is almost empty a By-stander be desired to lift up the brass Key formerly described as a stopple in the brass Cover he will finde it a very difficult thing to do so if the Vessel be well exhausted and even when but a moderate quantity of Air has been drawn out he will when he has lifted it up a little so that it is somewhat loose from the sides of the lip or socket which with the help of a little oyl it exactly filled before he will I say finde it so difficult to be lifted up that he will imagine there is some great weight fastned to the bottom of it And if as sometimes has been done for merriment onely a Bladder be tyed to it it is pleasant to see how men will marvail that so light a Body filled at most but with Air should so forcibly draw down their hand as if it were fill'd with some very ponderous thing whereas the cause of this pretty Phaenomenon seems plainly enough to be onely this That the Air in the Receiver being very much dilated its Spring must be very much weakn'd and consequently it can but faintly press up the lower end of the stopple whereas the Spring of the external Air being no way debilitated he that a little lifts up
press'd on the Bladder the internal Air not finding the wonted resistance first swell'd and distended the Bladder and then broke it with so wide and crooked a rent as if it had been forcibly torn assunder with hands After which a second Bladder being convey'd in the Experiment was repeated with like success And I suppose it will not be imagin'd that in this case the Bladder was broken by its own Fibres rather then by the Imprison'd Air. And of this Experiment these two Phaenomena may be taken notice of The one that the Bladder at its breaking gave a great report almost like a Craker And the other That the Air contain'd in the Bladder had the power to break it with the mention'd Impetuosity long before the ambient Air was all or near all drawn out of the Receiver But to verifie what we say in another Discourse where we show That even true Experiments may by reason of the easie mistake of some unheeded Circumstance be unsuccessfully try'd we will Advertise on this occasion that we did oftentimes in vain try the breaking of Bladders after the manner above-mention'd Of which the cause appear'd to be this That the Bladders we could not break having been brought us ready blown from those that sold them were grown dry before they came to our hands whence it came to pass that if we afterwards ty'd them very hard they were apt to fret and so become unserviceable and if we ty'd them but moderately hard their stiffness kept them from being clos'd so exactly but that when the included Air had in the exhausted Receiver distended them as much as easily it could it would in part get out between the little wrinkles of the Sphincter of tâ—e Neck Whence also it usually happen'd that upon the letting in the Air from without the Bladders appear'd more flaccid and empty then before they were put in whereas when the Bladders were brought us moist from the Butchers we could without injuring them tye their necks so close that none of the Air once blown in could get out of them but by violently breaking them It will not be amiss on this occasion to point at something which may deserve a more deliberate Speculation then we can now afford it namely that the Elastical Power of the sâ—me Quantity of Air may be as well Encreas'd by the Agitation of the Aërial Particles whether onely moving them more swiftly and scattering them or also extending or stretching them out I determine not within an every way inclosing and yet yielding Body as Display'd by the withdrawing of the Air that press'd it without For we found that a Bladder but moderately fill'd with Air and strongly ty'd being a while held near the Fire not onely grew exceeding turgid and hard but afterwards being approach'd nearer to the Fire suddenly broke with so loud and vehement a noise as stony'd those that were by and made us for a while after almost deaf Experiment 6. HAving thus seen that the Air has an Elastical Power we were next desirous to know in some measure how far a parcel of Air might by this its own Spring be dilated And though we were not provided of Instruments fit to measure the dilatation of the Air any thing accurately yet because an imperfect measure of it was more desireable then none at all we devis'd the following Method as very easily practicable We took a limber Lambs Bladder which was thorowly wetted in fair Water that the sides of it being squeez'd together there might be no Air left in its folds as indeed we could not afterwards upon tryal discern any The neck of this Bladder was strongly tyed about that of a small Glass capable of holding five full drachmes of Water the Bladder being first so compress'd that all the included Air was onely in the Glass without being press'd there then the Pump being set awork after a few exsuctions the Air in the little Viol began to dilate it self and produce a small Tumor in the Neck of the Bladder and as the ambient Air was more and more drawn away so the included Air penetrated further and further into the Bladder and by degrees lifted up the sides and display'd its folds till at length it seem'd to have blown it up to its full extent whereupon the external Air being permitted to flow back into the Reciver repuls'd the Air that had fill'd the Bladder into its former narrow receptacle and brought the Bladder to be again flaccid and wrinkled as before Then taking out the Bladder but without severing it from the Glass we did by a hole made at the top of the Bladder fill the Vessel they both made up with Water whose weight was five Ounces five Drachmes and an half Five Drachmes whereof were above-mention'd to be the contents of the Bottle So that in this Experiment when the Air had most extended the Bladder it possess'd in all above nine times as much room as it did when it was put into the Receiver And it would probably have much inlarg'd its bounds but that the Bladder by its weight and the sticking together of its sides did somewhat resist its expansion And which was more considerable the Bladder appear'd tumid enough whilst yet a pretty deal of Air was left in the Receiver whose exsuction would according to our former Observation probably have given way to a further expansion of the Air especially supposing the dilatation not to be restrain'd by the Bladder SInce we wrote the other day the former Experiment we have met with some Glasses not very unfit for our purpose by means of which we are now able with a little more trouble to measure the expansion of the Air a great deal more accurately then we could by the help of the above-mention'd Bladder which was much to narrow to allow the Air its utmost distention We took then first a Cylindrical Pipe of Glass whose bore was about a quarter of an Inch in Diameter this Pipe was so bent and doubled that notwithstanding its being about two foot in length it might have been shut up into a small Receiver not a Foot high But by misfortune it crack'd in the cooling whereby we were reduced to make use of one part which was straight and intire but exceeded not six or seven Inches This little Tube was open at one end and at the other where it was Hermetically seal'd had a small Glass bubble to receive the Air whose dilatation was to be measur'd Along the side of this Tube was pasted a straight narrow piece of Parchment divided into twenty six equal parts marked with black Lines and Figures that by them might be measur'd both the included Air and its dilatation Afterwards we fill'd the Tube with Water almost to the top and stopping the open end with a Finger and inverting the Tube the Air was permitted to ascend to the above-mention'd Glass bubble And by reason this ascent was very slow it gave us the opportunity to mark how
it would possess We would gladly have tryed also whether the Air at its greatest expansion could be further rarified by heat but do what we could our Receiver leak'd too fast to let us give our selves any satisfaction in that particular Experiment 7. TO discover likewise by the means of that pressure of the Air both the strength of Glass and how much interest the Figure of a Body may have in its greater or lesser Resistance to the pressure of other Bodys we made these further tryals We causd to be blown with a Lamp â— round Glass bubble capable of containing by guess about five Ounces of Water with a slender neck about the bigness of a Swans Quill and it was purposely blown very thin as Viols made with Lamps are wont to be that the thinness of the matter might keep the roundness of the Figure from making the Vessel too strong Then having moderately emptyed the Receiver and taken it out of the Pump we speedily applyed to the Orifice of the bottom of it the Neck of the newly mention'd Glass carefully stopping the Crannys with melted Plaister that no Air might get in at them And after turning the Key of the Stop-cock we made a free passage for the Air to pass out of the bubble into the Receiver which it did with great celerity leaving the bubble as empty as the Receiver it self as appear'd to us by some Circumstances not now to be insisted on Notwithstanding all which the Vessel continuing as intire as before gave us cause to wonder that the bare Roundness of the Figure should inable a Glass almost as thin as Paper to resist so great a pressure as that of the whole incumbent Atmosphere And having reiterated the Experiment we found again that the pressure of the ambient Body thrusting all the parts inwards made them by reason of their arched Figure so support one another that the Glass remain'd as whole as at first Now that the Figure of the Glass is of great moment in this matter may be evinced by this other Experiment Experiment 8. WE took a Glass Helmet or Alembick delineated by the seventh Figure such as Chymists use in Distillations and containing by conjecture between two and three Pints The Rostrum or Nose of it mark'd with c was Hermetically closed and at the top of it was a hole into which was fitted and cemented one of the Shanks of a middle-siz'd Stop-cock so that the Glass being turn'd upside-down the wide Orifice which in common Glass-Helmets is the onely one was upwards and to that wide Orifice was fitted a cast Cover of Lead which was carefully cemented on to the Glass Then the other Shank of the Stop-cock being with Cement likewise fasten'd into the upper part of the Pump the exsuction of the Air was endeavoured But it was not long before the remaining Air being made much too weak to ballance the pressure of the ambient Air the Glass was not without a great noise crack'd almost half round along that part of it where it began to bend inwards As if in the Figure the crack had been made according to the Line ab and upon an endeavour to pump out more of the Air the crack once began appear'd to run on further though the Glass where it was broken seem'd to be by conjecture above ten some thought above twenty times as thick as the bubble mention'd in the foregoing Experiment This will perhaps make it seem strange that having taken another Glass bubble blown at the same time and like for ought we discern'd for size thickness and Figure to that thin one formerly mention'd and having seal'd it up Hermetically and suspended it in the Receiver the exsuction of the ambient Air did not enable the imprisoned Air to break or in the least to crack the bubble though the Experiment were laboriously try'd and that several times with bubbles of other sizes But that perhaps the heat of the Candle or Lamp wherewith such Glasses are Hermetically seal'd not to mention the warmth of his hands that seal'd it might so rarifie the contained Air as much to weaken its Spring may seem probable by the following Experiments Experiment 9. WE took a Glass Viol able to hold three or four Ounces of Water and of the thickness usual in Glasses of that size into the Neck of this was put a moderately slender Pipe of Glass which was carefully fasten'd with a mixture of equal parts of Pitch and Rosin to the Neck of the Viol and which reach'd almost to the bottom of it as the sixth Figure declares This Viol being upon a particular design fill'd with Water till that came up in it a pretty deal higher then the lower end of the Pipe was put into one of our small Receivers containing between a Pint and a Quart in such manner as that the Glass Pipe passing through a hole made purposely for it in the Leaden-Cover of the Receiver was for the most part of it without the Vessel which being exactly closed the Pump was set awork But at the very first exsuction and before the Sucker was drawn to the bottom of the Cylinder there flew out of the Viol a piece of Glass half as broad as the Palm of a Mans Hand and it was thrown out with such violence that hitting against the Neighboring side of the Receiver it not onely dash'd it self to pieces but crack'd the very Receiver in many places with a great noise that much surprised all that were in the Room But it seem'd that in so little a Receiver the Air about the Viol being suddenly drawn out the Air Imprison'd in the Vessel having on it the whole pressure of the Atmosphere to which by the Pipe open at both ends It and the Water were expos'd and not having on the other side the wonted pressure of the Ambient Air to ballance that other pressure the resistance of the Glass was finally surmounted and the Viol once beginning to break where it was weakest the external Air might rush in with violence enough to throw the crack'd parcel so forcibly against the Neighboring side of the Receiver as to break that too And this may be presumed sufficient to verifie what we delivered in that part of our Appendix to the first Experiment where we mention'd the almost equal pressure of the Air on either side of a thin Glass Vessel as the cause of its not being broken by the forcible Spring of the contain'd Air. But yet that it be not suspected that chance had an interest in so odde an Experiment as we have been Relating we will adde that for farther satisfaction we reiterated it in a round Glasse containing by guesse about six ounces of water this violl we put into such a small Receiver as was lately mention'd in such manner as that the bottome of it rested upon the lower part of the Pneumaticall Glasse and the Neck came out through the Leaden-Cover of the same at a hole made purposely for it
affirm it to be replenish'd with them as we may suppose that if they were gather'd together into one place without Intervals between them they would fill but a small part of the whole Receiver As in the thirteenth Experiment a piece of Match was inconsiderable for its bulk whilest its parts lay close together that afterwards when the Fire had scatter'd them into smoke seem'd to replenish all the Vessel For as elsewhere our Experiments have demonstrated both Light and the Effluvia of the Load-stone may be readily admitted into a Glass Hermetically seal'd though before their Admission as full of Air as hollow Bodies here below are wont to be so that upon the exsuction of the Air the large space deserted by it may remain empty notwithstanding the pretence of those subtle Corpuscles by which Lucid and Magnetical Bodies produce their effects And as for the Allegations above mention'd they seem to prove but that the Receiver devoy'd of Air May be replenish'd with some such Etherial Matter as some Modern Naturalists write of but not that it really is so And indeed to me it yet seems that as to those spaces which the Vacuists would have to be empty because they are manifestly devoid of Air and all grosser Bodies the Plenists if I may so call them do not prove that such spaces are replenish'd with such a subtle Matter as they speak of by any sensible effects or operations of it of which divers new Tryals purposely made have not yet shown me any but onely conclude that there must be such a Body because there cannot be a Void And the reason why there cannot be a Void being by them taken not from any Experiments or Phaenomena of Nature that clearly and particularly prove their Hypothesis but from their notion of a Body whose Nature according to them consisting onely in extension which indeed seems the property most essential to because inseparable from a Body to say a space devoid of Body is to speak in the School-mens Phrase a Contradiction in Adjecto This reason I say being thus desum'd seems to make the Controversie about a Vacuum rather a Metaphysical then a Physiological Question which therefore we shall here no longer debate finding it very difficult either to satisfie Naturalists with this Cartesian Notion of a Body or to manifest wherein it is erroneous and substitute a better in its stead But though we are unwilling to examine any further the Inferences wont to be made from the Torricellian Experiment yet we think it not impertinent to present Your Lordship with a couple of Advertisements concerning it First then if in trying the Experiment here or elsewhere you make use of the English measures that Mathematicians and Tradesmen are here wont to imploy You will unless you be forewarn'd of it be apt to suspect that those that have written of the Experiment have been mistaken For whereas men are wont generally to talk of the Quick-silver's remaining suspended at the heighth of between six or seven and twenty Inches we commonly observ'd when divers years since we first were sollicitous about this Experiment that the Quick-silver in the Tube rested at about 29 Inches an half above the surface of the Restagnant Quick-silver in the Vessel which did at first both amaze and perplex us because though we held it not improbable that the difference of the grosser English Air and that of Italy and France might keep the Quick-silver from falling quite as low in this colder as in those warmer Climates yet we could not believe that that difference in the Air should alone be able to make so great a one in the heights of the Mercurial Cylinders and accordingly upon enquiry we found that though the various density of the Air be not to be over-look'd in this Experiment yet the main Reason why we found the Cylinder of Mercury to consist of so many Inches was this That our English Inches are somewhat inferior in length to the digits made use of in Forein Parts by the Writers of the Experiment The next thing I desire Your Lordship to take notice of is That the heigth of the Mercurial Cylinder is not wont to be fouÌ„d altogether so great as really it might prove by reason of the negligence or incogitancy of most that make the Experiment For ofâ—â—n times upon the opening of the inverted Tube into the Vessell'd Mercury you may observe a bubble of Air to ascend from the bottom of the Tube through the subsiding Quick-silver to the top and almost always you may if you look narrowly take notice of a multitude of small bubbles all along the inside of the Tube betwixt the Quick-silver the glass not now to mention the Particles of Air that lye conceal'd in the very Body of the Mercury Many of which upon the Quick-silvers forsaking the upper part of the Tube do break into that deserted space where they finde little or no resistance to their expanding of themselves Whether this be the reason that upon the Application of warm Bodies to the emptyed part of the Tube the subjacent Mercury would be depress'd somewhat lower we shall not determine though it seem very probable especially since we found that upon the application of Linnen cloaths dipped in Water to the same part of the Tube the Quick-silver would somewhat ascend as if the cold had condens'd the Imprison'd Air that press'd upon it into a lesser room But that the deserted space is not wont to be totally devoid of Air we were induc'd to think by several Circumstances For when an eminent Mathematician and excellent Experimenter had taken great pains and spent much time in accuratly filling up a Tube of Mercury we found that yet there remain'd store of inconspicuous bubbles by inverting the Tube letting the Quick-silver fall to its wonted heighth and by approaching by degrees a red hot Iron to the out-side of the Tube over against the upper part of the Mercurial Cylinder for hereby the little unheeded bubbles being mightily expanded ascended in such numbers and so fast to the deserted space that the upper part of the Quick-silver seem'd to our wonder to boyl We further observ'd That in the tryals of the Torricellian Experiment we have seen made by others and one excepted all our own we never found that upon the inclining of the Tube the Quick-silver would fully reach to the very top of the seal'd end which argued that there was some Air retreated thither that kept the Mercury out of the unreplenish'd space If Your Lordship should now demand what are the best expedients to hinder the intrusion of the Air in this Experiment we must answer That of those which are easily intelligible without ocular demonstration we can at present suggest upon our own tryals no better then these First at the open end of the Tube the Glass must not onely be made as even at the edges as you can but it is very convenient especially if the Tube be large that
erroneousness of the Cartesian Hypothesis concerning the Ebbing and Flowing of the Sea which Des Cartes ascribes to the greater pressure made upon the Air by the Moon and the Intercurrent Ethereal Substance at certain times of the Day and of the Lunary Moneth then at others But in regard we found the Quick-silver in the Tube to move up and down so uncertainly by reason as it seems of accidental mutation in the Air I somewhat doubt whether we shall finde the Altitude of the Quick-silver to vary as regularly as the Experiment is ingeniously propos'd The success we shall God permitting us to make tryal of it acquaint Your Lordship with and in the mean time take notice that when we had occasion to take the Tube out of the Frame after it had staid there part of November and part of December a good Fire being then in the room because it was a Snowy day we found the Quick-silver in the Tube to be above the upper surface of the subjacent Mercury 29 Inches three quarters If Your Lordship should now ask me what are the true causes of this varying altitude of the Mercurial Cylinder I should not undertake to answer so difficult a question and should venter to say no more then that among divers possible causes to which it may be ascribed it would not be perhaps absurd to reckon these that follow First then we may consider that the Air in the upper part of the Tube is much more rarified and therefore more weak then the external Air as may appear by this among other things That upon the inclining of the Tube the Quick-silver will readily ascend almost to the very top of it and so take up eight or nine tenth parts and perhaps more of that space which it deserted before which would not happen if that whole space had been full of unrarified Air since that as tryal may easily satisfie you would not have suffer'd it self to be thrust into so narrow a room by so weak a pressure So that although in our Tube when the included Air was heated the Quick-silver was somewhat depress'd Yet there is this difference betwixt such a Tube and common Weather-Glasses that in these the included and the ambient Air are in an Aequilibrium as to pressure and the weight of the Water that keeps them separate is scarce considerable Whereas in such a Tube as we are speaking of the Air within is very much more dilated then that without and 't is not so much the spring or resistance of the included Air as the weight of the Mercurial Cylinder it self that hinders the Quick-silver from ascending higher for if we should suppose that deserted part of the Tube perfectly devoid of Air yet would the Quick-silver rise but a little higher in it and be far from filling it in regard the outward Air would not be able to impel up such a weight much higher whereas it may by our former Experiments appear that if all the Air in the upper part of a Weather-Glass were away the Water would be impell'd up to the very top of it though the Pipe were above thirty Foot long We may next consider that this rarified Air at the upper part of our Tube being exactly shut up betwixt the Glass and the Quick-silver it was scarce subject to any discernable alterations save those it receiv'd from heat and cold And we may further consider that yet the external Air or Atmosphere is subject to many alterations besides them that proceed from either of those Qualities For the Experiment that occasion'd this Discourse seems to make it probable enough that there may be strange Ebbings and Flowings as it were in the Atmosphere or at least that it may admit great and sudden Mutations either as to its Altitude or its Density from causes as well unknown to us as the effects are unheeded by us And that You may not think that there is nothing in Nature but our Experiment that agrees with this our conjecture we might put Your Lordship in minde of the Pains and Aches that are often complain'd of by those that have had great Wounds or Bruises and that doe presage great Mutations in the Air oftentimes whilst to strong and healthy Persons no sign of any such thing appears And that is also very memorable to this purpose which I remember I have somewhere read in a Book of the Ingenious Kircherus who giving a pertinent admonition concerning the various refractions that may happen in the Air relates That during his stay in Malta he often saw Mount Aetna though the next day notwithstanding its being extreamly clear he could not see it adding that Vintemillius a very Learned Person did oftentimes from a Hill he names behold the whole Island he calls Luprica protuberant above the Sea though at other times notwithstanding a clear Sky he could not see it And though perhaps this may be in part ascribed to the various light position of the sun or to the various disposition of the Spectators eye or peradventure to some other cause yet the most probable cause seems to be the differing Density of the Air occasion'd by Exhalations capable to increase the refraction and consequently bring Beams to the Eye which otherwise would not fall on it We have likewise in another Treatise mention'd our having often observ'd with Telescopes a plenty of Steams in the Air which without such a help would not be taken notice of and which as they were not at all times to be seen even through a Telescope so they did sometimes especially after a shower of Rain hastily disappear and when we have visited those places that abound with Mines we have several times been told by the Diggers that even when the Sky seem'd clear there would not seldom suddenly arise and sometimes long continue a certain Steam which they usually call a damp so gross and thick that it would oftentimes put out their very Candles if they did not seasonably prevent it And I think it will easily be granted that the ascension of such Steams into this or that part of the Air and their mixing with it are very like to thicken it as on the other side either heat or the sudden condensation of the Air in another part of the Atmosphere to mention now no other causes are capable of rarifying it Nor will it very much import the main scope of our Discourse whether it be suppos'd that the copious Steams the earth sends into the air thicken that part of the Atmosphere that receives them and make it more heavy Or that sometimes the Fumes may ascend with such celerity that though the Air be thicken'd yet they rather diminish then encrease its gravitation in regard that the quickness of their ascent not onely keeps them from gravitating themselves but may hinder the pressing downwards of many Aërial Corpuscles that they meet with in their way upwards This I say is of no great importance to our present Discourse since
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 Schottus Mechâ—â— hydrauâ—icopneâ—mat Part 3. Claâ—â— 1. That amongst the other rarities to be met with in that great Repository of them the Musaeum 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 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 Natural Moâ—al Hist. of the Indies Lib. 3. C. 9. I remember indeed that the Learned Iosephus 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 Geogr. Genâ—â—al Lib. 1. c. 19. that the accurate Varenius tells 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 â—aline 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-Armoniack may 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 Aeolipile 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 Aeolipile 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 Aeâ—lipile 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 Aeolipile 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 Aeolipile 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 Aeolipile 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. 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 Aeolipile 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 Aeolipile 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 Aeolipile almost 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 Aeolipile when t is taken very hot from the Fire immersing 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 whereinto the neck was plunged Which bubbles seem manifestly to proceed from hence that for a while the heat in the Aeolipile 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 Aeolipile 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 't is 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 Aeolipile 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 Aeolipile 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 Aeolipile 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 〈…〉 〈◊〉 lib. 9. p. 309. Cum eodem tempore quo haec scripsi summi Pont Innocentii X mi mandato organi hydraulici in horto Quirinali constituendi cur a mihi commendata esset Aeoliam cameram insigni sane successu construi jussimus eâ quae sequitur ratione Erat longitudo sive altitudo camerae AH 5 Pedum Latitudine 3 fere ex lateribus constructa 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 parabat exitum Aqua itáque per canalem G maximo impetu ruenâ— vehementissimum ventum mox intus excitabat qui ventus nimia humiditate imbutus ut purior exiret sicciorque Diaphragmata illa in cribri modum pertusa ordinata sunt Intra haec enim aquae vehemens agitatio rupta fractaque aerem puriorem per A canalem subtilioremque emittebat Verum cum postea inventuÌ„ sit acreÌ„ plus aequo humiduÌ„ interioribus Organi meatibus maximuÌ„ detrimentum inferre Hinc ut aer aquosus siccissimam coÌ„sistentiam acquireret ordinavimus canalem plumbeum QR in helicem contortum vasi S aliquantulum capaciori in modum Urnae efformato inserâ—um Intra urnam enim plumbeam canalem tortuosum illisus aer humidus ita ab omni aquositate defaecabatur ut ex furno in Organum derivatus dici potuerit Urna S canalis tortuosus QR ultimum orificium Q inseritur anemothecae organi Et hunc modum organis hydraulicis omniuÌ„ aptissimuÌ„ reperi Debet autem camera illa situari in loco quantum fieri potest sicciori ita ut longo canali aqua intra 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 't is 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 Aeolian 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 I remember 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 tortuous a Pipe of Lead as that describ'd by our Author since we see in the Heads of Stills and the Necks of Aeolipiles 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 open-mouth'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 upon 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 Epicurus 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
much obstinacy that not onely about the upper part of the Jar there appear'd a good number of bubbles but very much smaller then those we saw the first time but afterwards there came from the bottom of the Jar bubbles about the bigness of smal Peas which the Pump being still kept going follow'd one another to the number of forty coming from the stopp'd Violl whose mouth it seems had not been shut so strongly and closely but that the included Air dilating it self by its own spring made it self some little passage betwixt the Wall and the Glass and got away in these bubbles after which the unstopp'd Glass began to float again the Air shut up in it being manifestly so dilated as to expel a good part of the Water but not so much as to break quite thorow And at length when our expectation of it was almost tired out the heavier of the two Viols began to come aloft and immediately to subside again which appear'd to be occasion'd by the Air within it whose bulk and spring being weaken'd by the recess of the forty bubbles before-mention'd it was no longer able as formerly to break forcibly through the incumbent Water but forming a bubble at the mouth of the Glass boyed it up towards the top and there getting away left it to sink again till the pressure of the Air in the Receiver being further taken off the Air in the Viol was permitted to expand it self further and to create another bubble by which it was again for a while carried up And it was remarkable that though after having emptyed the Receiver as far as well we could we ceas'd from pumping yet the Vessel continuing more stanch then it was wont this ascent and fall of the Viol was repeated to the ninth time the included Air by reason of the smalness of the vent at which it must pass out being not able to get away otherwise then little by little and consequently in divers such parcels as were able to constitute bubbles each of them big enough to raise the Viol and keep it aloft until the avolation of that bubble Whereby it may appear that the grand rule in Hydrostaticks That a Body will swim in the Water in case it be lighter then as much of that Water that equals it in bulk will hold likewise when the pressure of the Atmosphere is in very great measure if not when it is totally taken off from the Liquor and the Body though it were worth inquiring what it is that so plentifully concurs to fill the bubbles made in our Experiment by the so much expanded Air for to say with the old Peripatetick Schools That the Air in Rarefaction may acquire a new extent without the admission of any new substance would be an account of the Phaenomenon very much out of date and which I suppose our Modern Naturalists would neither give nor acquiess in I know not whether it may be requisite to adde that in this Experiment as in the former the outward Air being let in did soon precipitate the floating Viol. But I think it will not be amiss to note that congruously to what hath been above recorded of the vast expansion of the Air the Water which in the heavier Viol succeeded in the room of those forty odde if not fifty great bubbles of Air which at several times got out of it amounted but to a very inconsiderable bigness Experiment 26. IT having been observ'd by those that have consider'd what belongs to Pendulums a Speculation that may in my poor judgement be highly useful to the Naturalists that their Vibrations are more slowly made and that their motion lasts less in a thicker then in a thinner Medium We thought it not amiss to try if a Pendulum would swing faster or continue swinging longer in our Receiver in case of the exsuction of the Air then otherwise Wherefore we took a couple of round and polish'd Pendulums of Iron or Steel of equal bigness as near as we could get the Artificer to make them and weighing each of them twenty Dragmes wanting as many Grains One of these we suspended in the cavity of the Receiver by a very slender silken string of about seven Inches and a half in length from the cover of the Receiver to which it was fasten'd Then by inclining the Engine we made the Pendulum swing too and â—ro in it and describ'd as long Arches as in the capacity of so brittle a Vessel we thought safe and convenient And one of the Assistants telling the recursions of the other Pendulum hanging in the free Air by a string of about the same length we shorten'd and lengthen'd this other Pendulum till it appear'd to keep the same pace in its Vibrations with that shut up in the Receiver Then having carefully drawn away the Air we did again set the Pendulum in the Receiver a vibrating and giving the other Pendulum such a motion as made it describe an Arch according to ones ghess equal to that of the included Pendulum we reckon'd one of us the Recursions of that Pendulum which was swinging within the Receiver and another of us that which was moving in that which one would think a much more resisting medium the Air. But once one of us reckon'd near two and twenty Recursions of the included Pendulum whilst the other reckon'd but twenty of the Pendulum that vibrated without And another time also the former of these Pendula was reckon'd to have made one and twenty Recursions wherein the other made but twenty Yet this Experiment seem'd to teach us little save that the difference betwixt the motion of such a Pendulum in the common Air and in one exceedingly rarified is scarce sensible in Vessels no bigger then our Receiver especially since though during this Experiment it held very well yet we could not suppose it to be altogether devoid of Air. We observ'd also that when the Receiver was full of Air the included Pendulum continu'd its Recursions about fifteen minutes or a quarter of an hour before it left off swinging and that after the exsuction of the Air the Vibration of the same Pendulum being fresh put into motion appear'd not by a minutes Watch to last sensibly longer So that the event of this Experiment being other then we expected scarce afforded us any other satisfaction then that of our not having omitted to try it And whether in case the tryal be made with a Pendulum much less disproportionate to the Air then Steel is the event will much better answer expectation experience may be consulted THat the Air is the medium whereby sounds are convey'd to the Ear Experiment 27. has been for many Ages and is yet the common Doctrine of the Schools But this Received Opinion has been of late oppos'd by some Philosophers upon the account of an Experiment made by the Industrious Kircher and other Learned Men who have as they assure us observ'd That if a Bell with a Steel Clapper be
an Instrument shut up into our Receiver would when the ambient Air was suck'd out at all tremble if in another Instrument held close to it but without the Receiver a string tun'd as Musicians speak how properly I now examine not to an Unison with it were briskly toucht and set a Vibrating This I say we purpos'd to try to see how the motion made in the Air without would be propagated through the cavity of our evacuated Receiver But when the Instrument wherewith the tryal was to be made came to be imploy'd it prov'd too big to go into the Pneumatical Vessel and we have not now the conveniency to have a fitter made We thought likewise to convey into the Receiver a long and slender pair of Bellows made after the fashion of those usually employ'd to blow Organs and furnish'd with a small Musical instead of an ordinary Pipe For we hop'd that by means of a string fastned to the upper part of the Bellows and to the moveable stopple that makes a part of the Cover of our Receiver we should by frequently turning round that stopple and the annexed string after the manner already often recited be able to lift up and distend the Bellows and by the help of a competent weight fasten'd to the same upper part of the Bellows we should likewise be able at pleasure to compress them and by consequence try whether that subtler matter then Air which according to those that deny a Vacuum must be suppos'd to fill the exhausted Receiver would be able to produce a sound in the Musical Pipe or in a Pipe like that of ordinary Bellows to beget a Wind capable to turn or set a moving some very light matter either shap'd like the Sails of a Wind-Mill or of some other convenient form and expos'd to its Orifice This Experiment I say we thought to make but have not yet actually made it for want of an Artificer to make us such a pair of Bellows as it requires We had thoughts also of trying whether or no as Sounds made by Bodies in our Receiver become much more languid then ordinary by reason of the want of Air so they would grow stronger in case there were an unusual quantity of Air crouded and shut up in the same Vessel which may be done though not without some difficulty by the help of the Pump provided the Cover and Stopple be so firmly fasten'd by binding and Cement or otherwise to the Glass and to each other that there be no danger of the condens'd Airs blowing of either of them away or its breaking through the junctures These thoughts My Lord as I was saying we entertain'd but for want of leasure as of as good Receivers as ours to substitute in its place in case we should break it before we learn'd the skill of condencing the Air in it we durst not put them in practice Yet on this occasion give me leave to advertise Your Lordship once for all That though for the reasons newly intimated we have Onely in the seventeenth Experiment taken notice that by the help of our Engine the Air may be condens'd as well as rarified yet there are divers other of our Experiments whose Phaenomena it were worth while to try to vary by means of the compression of the Air. Experiment 28. WE taught among divers other things when we discours'd of our first Experiment That the Air shut up in our Receiver presseth as strongly upon the Bodies shut up with it as if they were expos'd to the pressure of the whole Atmosphere That this was not inconsiderately propounded we hope Your Lordship has gather'd from divers of the things already recited But yet perhaps it will not be amiss to subjoyn by way of further confirmation of the same truth the following Experiment which should have accompanied the 20th but the Paper where in the one was written chanc d not to be at hand when the other was sent away We convey'd into the Receiver a new Glass Viol capable of holding about 6 or 7 ounces of Water into which we had before put 2 or 3 Spoon-fulls of that Liquor and stopt it close with a fit Cork The Pneumatical Vessel being empty'd there appear'd not any change in the inclos'd Water the Air imprison'd with it not having the force to blow out the stopple which event though it were no other then we expected was differing from what we desir'd For we would gladly have seen what change would have appear'd in the Water upon the Bottles being suddenly unstopp'd in a place where the ambient Body was so differing from our common Air. Wherefore we did again put in the Viol but less strongly clos'd then formerly though as strongly stopt as seem'd requisite on ordinary occasions But when the Air was pump'd out of the Receiver that within the Viol did quickly as we expected find or make it self little passages to get out at as we argu'd from this That whereas when the Viol was put in the time before the Water remain'd all the while perfectly free from bubbles at this time the bottom of the Glass appear'd all cover'd with them and they upon the regress of the excluded Air into the Receiver did presently flag and shrink up From these tryals it seem'd deducible enough that whil'st the Viol continu'd to be well stopt the included Water did from the Air shut up with it sustain a pressure equal to that of the Atmosphere since till the Air could get out of the Glass there appear'd no bubbles in the Water notwithstanding the want of pressure in the ambient Body But to be sure to reach the chief end of our Experiment we made use of this other expedient We caus'd a convenient quantity of Water to be put and Hermetically shut up into a Glass Egge to whose long Neck which was purposely made of an unequal thickness was fasten'd to one end of a string whose other end was ty'd to the Cover of our Receiver after the manner elsewhere mention'd already Then the Egge being convey'd into the Pneumatical Vessel and that being evacuated we did by turning the brass Stopple formerly describ'd amongst the parts of our Engine so shorten the string as to break the Glass whereby liberty being given to the Air imprison'd in the Egge to pass into the capacity of the Receiver the sudden recess of the Air made the bubbles in a trice appear so numerous and ascend so swiftly in the Water that their motion look'd like that of a violent shower of Rain save that the bubbles did not like the drops of Rain tend downwards but upwards which made me resemble this Phaenomenon to what I have seen happen in the dissolution of Seed-Pearl in some acid Menstruum in which if a good quantity of the little Pearls be cast whole they will at first if the Menstruum be sharp enough be carryed in swarms from the bottom to the top of the Liquor We will adde that without sealing up the
the reason why if a long Pipe exactly clos'd at one end be fill'd top-ful of Water and then inverted no Liquor will fall out of the open Orifice Or to use a more familiar Example when they teach that the cause why in a Gardiner's watering Pot shap'd conically or like a Sugar-Loaf fill'd with Water no Liquor fals down through the numerous holes at the bottome whilst the Gardiner keeps his Thumb upon the Orifice of the litle hole at the top and no longer must be that if in the case proposed the Water should descend the Air being unable to succeed it there would be left at the upper and deserted part of the Vessel a Vacuum that would be avoided if the hole at the top were open'd When I say they alleadge such Experiments the Tendency of them seems plainly to import that they mean by a Vacuum any space here below that is not fill'd with a visible body or at least with Air though it be not quite devoy'd of all Body whatsoever For why should Nature out of her detestation of a Vacuum make Bodies act contrary to their own Tendency that a place may be fill'd with Air if its being so were not necessary to the avoiding of a Vacuum Taking then a Vacuum in this vulgar and obvious sence the common opinion about it seems lyable to several Exceptions whereof some of the chief are suggested to us by our Engine It will not easily then be intelligibly made out how hatred or aversation which is a passion of the Soule can either for a Vacuum or any other object be suppos'd to be in Water or such like inanimate Body which cannot be presum'd to know when a Vacuum would ensue if they did not bestirre themselves to prevent it nor to be so generous as to act contrary to what is most conducive to their own particular preservation for the publique good of the Universe As much then of intelligible and probable Truth as is contain'd in this Metaphoricall Expression seems to amount but to this That by the Wise Author of Nature who is justly sayd to have made all things in number weight and measure the Universe and the parts of it are so contriv'd that it is as hard to make a Vacuum in it as if they studiously conspir'd to prevent it And how far this it selfe may be granted deserves to be further consider'd For in the next place our Experiments seem to teach that the supposed Aversation of Nature to a Vacuum is but accidental or in consequence partly of the Weight and Fluidity or at least Fluxility of the Bodies here below and partly and perhaps principally of the Spring of the air whose restless endeavor to expand it selfe every way makes it either rush in it selfe or compel the interpos'd bodys into all spaces where it finds no greater resistance than it can furmount And that in those motions which are made ob fugam Vacui as the common phrase is Bodys act without such generosity Consideration as is wont to be ascrib'd to them is apparent enough in our 32d Experiment where the torrent of Air that seem'd to strive to get into the Empty'd Receiver did plainly prevent its own Designe by so impelling the Valve as to make it shut the only Orifice the Air was to get in at And if afterwards either Nature or the internal Air had a designe the external Air should be attracted they seem'd to prosecute very unwisely by continuing to suck the Valve so strongly when they found that by that Suction the Valve it selfe could not be drawn in Whereas by forbearing to suck the Valve would by it's own weight have fall'n down and suffer'd the excluded Air to returne freely and to fill again the exhausted Vessel And this minds me to take notice of another deficiency pointed at by our Experiments in the common Doctrine of those Plenâ—sts we reason with for many of those unusual motions in Bodies that are sayd to be made to escape a Vacuum seem rather made to fill it For why to instance in our newly mention'd Experiment assoon as the Valve was depress'd by the weight we hung at it should the Air so impetuously and copiously rush into the cavity of the Receiver it there were before no vacant room there to receive it and if there were then all the while the Valve kept out the Air those lâ—tle spaces in the Receiver which the corpuscles of that Air afterwards fill'd may be concluded to have remain'd empty So that the seeming violence imploy'd by Nature on the occasion of the evacuating of the Vessel seems to have come too late to hinder the making of Vacuities in the Receiver and only to have assoon as we permitted fill'd up with Air those that were already made And as for the Care of the Publique Good of the Universe ascrib'd to dead and stupid Bodies wee shall only demand why in our 19th Experiment upon the Exsuction of the ambient Air the Water deserted the upper half of the Glass-Tube and did not ascend to fill it up till the external Air was let in upon it whereas by its easy and sudden regaining that upper part of the Tube it appear'd both that there was there much space devoid of Air and that the Water might with small or no resistance have ascended into it if it could have done so without the impulsion of the readmitted Air which it seems was necessary to mind the Water of its formerly neglected Duty to the Universe Nay for ought appeares ev'n when the excluded Air assoon as 't was permitted rusht violently into our exhausted Receiver that flowing in of the Air proceeded rather from the determinate Force of the Spring of the neighbouring Air then from any endeavour to fill up much less to prevent vacuity's For though when as much Air as will is gotten into our Receiver our present Opponents take it for granted that it is full of Air yet if it be remembred that when we made our 17th Experiment we crouded in more Air to our Receâ—â—er than it usually holds and if we also consider which is much more the Air of the same consistence with that in our Receiver may in wind-guns as is known and as we have try'd be compressed at least into halfe its wonted room I say at least because some affirme that the Air may be thrust into an 8th or a yet smaller part of its ordinary extent it seems necessary to admit either a notion of condensation rarefaction that is not intelligible or that in the capacity of our Receiver when presum'd to be full of Air there yet remain'd as much of space as was taken up by all the aërial corpuscles unpossessed by the Air. Which seemes plainly to infer that the Air that rush'd into our empty'd vessel did not doe it precisely to fill up the Vacuities of it since it left so many unfill'd but rather was thrust in by the pressure of the contiguous Air which as it could not
somewhat thicker within whose cavity it was imprison'd whereas Air pent up and agitated by heat is able to perform so much more considerable effects that not to mention those of Rarefaction that are more obvious the Learned Jesuit Cabaeus he that writ of the Load-stone relates P Nicol Cab lib 4. Metâ—oâ— Aristot That he saw a Marble Pillar so vast that three men together with display'd arms could not imbrace it and that 1000 Yoke of Oxen drawing it several ways with all their strength could not have torn it assunder quite broken off in the midst by reason of some Wood which happening to be burnt just by the Pillar the heat proceeding from the neighboring Fire so rarified some Air or Spirituous Matter which was shut up in the cavities of the Marble that it broke through the solid Body of the Stone to obtain room to expand it self I remember I have taken notice that probably the reason why the included Air did not break the hermetically seal'd Bubbles that remain'd intire in our emptyed Receiver was That the Air being somewhat rarefied by the Flame imploy'd to close the Glass its Spring upon the recess of the heat grew weaker then before But though we reject not that ghess yet it will not in the present case serve the turn because that much smaller Glass bubbles exactly clos'd will by the included Air though agitated but by the heat of a very moderate Fire be made to fly in pieces Whether we may be assisted to salve this Problem by considering that the heat does from within vehemently agitate the Corpuscles of the Air and adde its assistance to the Spring they had before I shall not now examine since I here but propose a Problem and that chiefly that by this memorable Story of Cabaeus notice may be taken of the prodigious power of Rarefaction which hereby appears capable of performing stranger things then any of our Experiments have hitherto ascrib'd to it We should hence My Lord immediatly proceed to the next Experiment but that we think it fit on this occasion to acquaint You with what some former tryals though not made in our Engine have taught us concerning what we would have discover'd by the newly mention'd Bubble that broke And this the rather because a great part of this letter supposing the gravity of the Aire it will not be impertinent to determine more particularly then hitherto we have done what gravity we ascribe to it We tooke then an Aeolipile made of copper weighing six ounces five drachms and eight and forty graines this being made as hot as we durst make it for feare of melting the mettle or at least the Sodar was removed from the fire and immediately stopped with hard wax that no Aire at all might get in at the little hole wont to be left in Aeolipiles for the fumes to issue out at Then the Aeolipile being suffer'd leasurely to coole was again weighed together with the wax that stopt it and was found to weigh by reason of the additionall weight of the wax six ounces sixe drachmes and 39 graines Lastly the wax being perforated without taking any of it out of the Scale the externall Aire was suffered to rush in which it did with some noyse and then the Aeolipile and wax being againe weighed amounted to six ounces six drachmes and 50. graines So that the Aeolipile freed as farre as our fire could free it from it's Aire weighed lesse then it selfe when replenished with Air full eleven graines That is the Air containable within the cavity of the Aeolipile amounted to eleven graines and somewhat more I say somewhat more because of the particles of the Air that were not driven by the fire out of the Aeolipile And by the way if there be no mistake in the observations of the diligent Mersennus it may seeme strange that it should so much differ from 2. or 3. of ours in none of which we could rarifie the Air in our Aeolipile though made red hot almost all over and so immediately plung'd into cold water to halfe that degree which he mentions namely to 70. times it 's naturall extent unlesse it were that the Aeolipile he imploy'd was able to sustaine a more vehement heat then ours which yet we kept in so great an one that once the soder melting it fell asunder into the two Hemispheres it consists of The fore-mentioned way of weighing the Air by the help of an Aeolipile seems somewhat more exact then that which Mersennus used In that in ours the Aeolipile was not weighed till it was cold whereas in his being weighed red hot it is subject to loose of it's substance in the cooling for as we have elsewhere noted on another occasion Copper heated red hot is wont in the cooling to throw off little thin scales in such plenty that having purposely watcht a Copper Aeolipile during its refrigeration we have seen the place round about it almost covered with those little scales it had every way scatter'd which however they amount not to much ought not to be over-looked when 't is so light a body as Air that is to be weighed We will not examine whether the Aeolipile in cooling may not receive some little increment of weight either from the vapid or faline Steames that wander up and downe in the Air But we will rather mention that for the greater exactnesse we imployed to weigh our Aeolipile both when fill'd onely with Air and when replenisht with Water a paire of scales that would turne as they speak with the fourth part of a grain As to the proportion of weight betwixt Air and Water some learned men have attempted it by wayes so unaccurate that they seeme to have much mistaken it For not to mention the improbable accounts of Kepler and others The learned and diligent Ricciolus having purposely endeavoured to investigate this proportion by meanes of a thin bladder estimates the weight of the Air to that of the Water to be as one to ten thousand or thereabouts And indeed I remember that having formerly on a certain occasion weighed a large bladder full of Air and found it when the Air was all squeesed out to have contained fourteen graines of Air. I found the same bladder afterwards fill'd with water to containe very neer 14. pound of that liquor according to which account the proportion of Air to Water was almost as a graine to a pound that is as one to above 7600. To this we may adde that on the other side Galileo himselfe using another but an unaccurate way too defined the Air to be in weight to Water but as one to 4. hundred But the way formerly proposed of weighing the Air by an Aeolipile seemes by great oddes more exact and as farre as we could ghesse seemed to agree well enough with the experiment made in our Receiver Wherefore it will be best to trust our Aeolipile in the enquiry we are about and according to our observations the water
of Light yet it was indeed but a whiteness which did as hath already been noted opacate as some speak the inside of the Glass Next we consider'd that our common Air abounds with Particles or little Bodies capable to reflect the Beams of Light Of this we might easily give divers proofs but we shall name but two The one that vulgar observation of the Motes that appear in Multitudes swimming up and down in the Air when the Sun-beams shooting into a Room or any other shady Place discover them though otherwise the eye cannot distinguish them from the rest of the Air The other proof we will take from what we and no doubt very many others have observ'd touching the Illumination of the Air in the Night And we particularly remember that being at some distance from London one Night that the People upon a very well-come Occasion testified their Joy by numerous Bon-fires though by reason of the Interposition of the Houses we could not see the Fires themselves yet we could plainly see the Air all enlighten'd over and near the City which argu'd that the lucid Beams shot upwards from the Fires met in the Air with Corpuscles opacous enough to reflect them to our Eyes A third thing that we considered was That white may be produc'd without excluding other ways or denying invisible Pores in the solidest Bodies when the continuity of a Diaphanous Body happens to be interrupted by a great number of Surfaces which like so many little Looking-glasses do confusedly represent a multitude of little and â—eemingly contiguous Images of the elucid Body We shall not insist on the explanation of this but refer You for it to what we have said in another Paper touching Colours But the Instances that seem to prove it are obvious For Water or whites of Eggs beaten to froth do lose their transparency and appear white And having out of one of our lesser Receivers carefully drawn out the Air and so order'd it that the hole by which the Water was to get in was exceeding small that the Liquor might be the more broken in its passage thorow it we observ'd with pleasure That the Neck being held under Water and the little hole newly mention'd being open'd the Water that rush'd in was so broken and acquired such a multitude of new Surfaces that the Receiver seem'd to be full rather of Milk then Water We have likewise found out That by heating a lump of Crystal to a certaâ—n degree and quenching it in fair Water it would be discontinu'd by such a multitude of Cracks which created new Surfaces within it that though it would not fall asunder but retain its former shape yet it would lose its transparency and appear white Upon these Considerations My Lord and some others it seem'd not absur'd to imagine That upon the rushing of the Air out of the Receiver into the empty'd Cylinder the Air in the Receiver being suddenly and vehemently expanded the Texture of it was as suddenly alter'd and the parts made so to shift places and perhaps some of them to change postures as during their new and vehement Motion and their varied Scituation to disturb the wonted continuity and so the Diaphaneity of the Air which as we have already noted upon its ceasing to be a transparent Body without the interposition of colour'd things must easily degenerate into white Several things there were that made this Conjecture seem the less improbable As first That the whiteness always appear'd greater when the Exsuction began to be made whil'st there was store of Air in the Receiver then when the Air was in great part drawn out And next That having exhausted the Receiver and apply'd to the hole in the Stop-cock a large bubble of clear Glass in such a manner that we could at pleasure let the Air pass out at the small Glass into the great one and easily fill the small one with Air again We observ'd with pleasure That upon the opening the passage betwixt the two Glasses the Air in the smaller having so much room in the greater to receive it the Dissilition of that Air was so great that the small Viol seem'd to be full of Milk and this Experiment we repeated several times To which we may adde That having provided a small Receiver whose upper Orifice was so narrow that I could stop it with my Thumb I observ'd that when upon the Exsuction of the Air the capacity of the Glass appear'd white if by a sudden removal of my Thumb I let in the outward Air that whiteness would immediately vanish And whereas it may be objected That in the Instance formerly mention'd Water turning from perspicuous to white there intervenes the Air which is a Body of a Heterogeneous nature and must turn it into Bubbles to make it lose its transparency We may borrow an Answer from an Experiment we deliver in another Treatise where we teach how to make two very volatile Liquors which being gently put together are clear as rock-Rock-water and yet will almost in a moment without the sub-ingression of Air to turn them into Bubbles so alter the disposition of their insensible parts as to become a white and consistent Body And this happens not as in the precipitation of Benjamin and some other Resinous Bodies which being dissolv'd in Spirit of Wine may by the effusion of fair Water be turn'd into a seemingly Milky substance For this whiteness belongs not to the whole Liquor but to the Corpuscles of the dissolv'd Gum which after a while subâ—iding leave the Liquor transparent themselves onely remaining white Whereas in our case 't is from the vary'd texture of the whole formerly transparent fluid Body and not from this or that part that this whitenesse results For the Body is white thorowout and will long continue so and yet may in process of time without any addition be totally reduc'd into a transparent Body as before But besides the Conjecture insisted on all this while we grounded another upon the following Observation which was That having convey'd some smoke into our Receiver plac'd against a Window we observ'd that upon the exsuction of the Air the Corpuscles that were swimming â—n it did manifestly enough make the Receiver seem more opacous at the very moment of the rushing out of the Air For considering that the whiteness whose cause we enquire of did but sometimes appear it seem'd not impossible but that at such times the Air in the Receiver might abound with Particles capable of reflecting the Light in the manner requisite to exhibit a white colour by their being put into a certain unusual Motion As may be in some measure illustrated by this That the new motion of the freshly mention'd Fumes made the inside of the Receiver appear somewhat darker then before And partly by the nature of our formerly mention'd smoking Liquor whose parts though they seem'd transparent whil'st they compos'd a Liquor yet when the same Corpuscles upon the unstopping of the Glass were put
into a new motion and dispos'd after a new manner they did opacate that part of the Air they mov'd in and exhibited a greater whiteness then that which sometimes appears in our Pneumatical Vessel Nor should we content our selves with this single Instance to manifest That little Bodies which being rang'd after one manner are Diaphanous and Colourless may by being barely agitated dispers'd and consequently otherways rang'd exhibite a colour if we were not unwilling to rob our Collection of Experiments concerning Colours But My Lord I foresee You may make some Objections against our proposed ghess which perhaps I shall scarce be able to answer especially if You insist upon having me render a Reason why our Phaenomenon appears not constantly I might indeed answer that probably it would do so if instead of our great Receiver we use such a small Viol as we have lately mention'd wherein the Dissilition of the Air being much greater is like to be the more conspicuous Since I remember not that we ever made our tryal with such small Vessels without finding the expected whiteness to appear But it would remain to be explicated why in our great Receiver the Phaenomenon should sometimes be seen and oftentimes not appear And though that Conjecture which we last made should not be rejected yet if we were further press'd to assign a reason why the Air should abound with such Particles as we there suppose more at one time then another we are not yet provided of any better Answer then this general one That the Air about us and much more that within the Receiver may be much alter'd by such causes as few are aware of For not to repeat those probable Arguments of this Assertion which we have occasionally mention'd here and there in the former part of this Epistle we will here set down two or three Instances to verifie the same Proposition First I finde that the Learned Iosephus Acosta Ioseph Acosta â—at Moâ— Hyst of the Indles lâ—b 3. cap. 9. among other Judicious Observations he made in America hath this concerning the Effects of some Winds There are says he Winds which naturally trouble the Water of the Sea and make it green and black others clear as Crystal Next we have observ'd That though we conveyd into the Receiver our Scales and the Pendula formerly mention'd clean and bright yet after the Receiver had been empty'd and the Air let in again the gloss or lustre both of the one and of the other appear'd tarnish'd by a beginning rust And in the last place we will subjoyn an Observation we made some Years ago which hath been heard of by divers Ingenious Men and seen by some of them We had with pure Spirit of Wine drawn a Tincture out of a certain Concrete which uses to be reckoned among Mineral Bodies And this Tincture being very pure and transparent we did because we put a great value upon it put into a Crystal Viol which we carefully stopp'd and lock'd up in a Press among some other things that we specially priz'd This Liquor being a Chymical Rarity and besides very defecate and of a pleasing Golden Colour we had often occasion to look upon it and so to take notice that one time it seem'd to be very much troubled and not clear as it was wont to be Whereupon we imagined that though it would be something strange yet it was not impossible that some Precipitation of the Mineral Corpuscles was then happening and that thence the Liquor was opacated but finding after some days that though the expected Precipitation had not been made yet the Liquor retaining its former vivid Colour was grown clear again as before we somewhat wondered at it and locking it up again in the same Press we resolved to observe both whether the like changes would again appear in our Tincture and whether in case they should appear they would be ascribable to the alterations of the Weather But though during the greatest part of a Winter and a Spring we took pleasure to observe how the Liquor would often grow turbid and after a while clear again Yet we could not finde that these Mutations depended upon any that were manifest in the Air which would be often dark and clouded when the Tincture was clear and transparent as on the other side in clear Weather the Liquor would appear sometimes troubled and more opacous So that being unable to give an account of these odde changes in our Tincture which we suppose we have not yet lost though we know not whether it have lost its fickle Nature either by those of the Air or any thing else that occurr'd to our thoughts we could not but suspect that there may be in divers Bodies as it were Spontaneous Mutations that is such changes as depend not upon manifest Causes But My Lord what has been all this while said concerning our Phaenomenon is offer'd to You not as containing a satisfactory Account of it but to assist You to give Your self one WE took a Glass Vessel Experiment 38. open at the top and into it we put a mixture of Snow and common Salt such a mixture as we have in another Treatise largely discoursed of and into the midst of this mixture we set a Glasse of a Cylindrical form closely stopp'd at the lower end with Plaister and open at the upper at which we fill'd it with common Water These things being let down into the Receiver and the Pump being set awork the Snow began to melt somewhat faster then we expected whether upon the account of the Exsuction of the Air or because there was but little of the Snow or whether for any other Reason it appeared doubtfull But however by that time the Receiver had been considerably exhausted which was done in lesse then ¼ of an hour we perceived the Water near the bottom of the Glass Cylinder to Freeze and the Ice by a little longer stay seem'd to encrease and to rise somewhat higher then the surface of the surrounding Liquor whereinto almost all the Snow and Salt were resolv'd The Glass being taken out it appear'd that the Ice was as thick as the inside of the Glass it fill'd though into that I could put my Thumb The upper surface of the Ice was very concave which whether it were due to any unheeded accident or to the exsuction of the Air we leave to be determin'd by further tryal And lastly the Ice held against the Light appear'd not destitute of Bubbles though some By-standers thought they were fewer then would have been found if the Water had been frozen in the open Air. The like Experiment we try'd also another time in one of our small Receivers with not unlike success And on this occasion My Lord give me leave to propose a Problem which shall be this Whence proceeds that strange force that we may sometimes observe in frozen Water to break the Bodies that Imprison it though hard and solid That there is such a
force in Water expos'd to Congelation may be gather'd not onely from what may be often observ'd in Winter of the bursting of Glasses too close stopp'd fill'd with Water or aqueous Liquors but by Instances as much more considerable as less obvious For I remember that an Ingenious Stone-cutter not long since complain'd to me That sometimes through the negligence of Servants the Rain being suffered to soak into Marble Stones the supervening violent Frosts would burst the Stones to the Professors no small damage And I remember another Tradesman in whose House I had Lodgings was last Winter complaining that even Implements made of Bell-metal being carelesly expos'd to the wet have been broken and spoil'd by the Water which having gotten into the little Cavities and Crannies of the Metal was there afterwards frozen and expanded into Ice And to these Relations In lâ—b 4. 〈…〉 we can adde one of the formerly mention'd Cabaeus's whereby they not onely may be confirm'd but are surpass'd For he tells us That he saw a huge Vessel of exceeding hard Marble split asunder by congel'd Water whose Rarefaction says our Author prov'd so vehement that the hardness of the Stone yielded to it and so a Vessel was broken which would not have been so by 100 Yoke of Oxen drawing it several ways I know My Lord that to solve this Problem it will be said That Congelation does not as is commonly but erroneously presum'd reduce water into less room then it possess'd before but rather makes it take up more And I have elsewhere prov'd by particular Experiments That whether or no Ice may be truly said to be Water rarefi'd for that seems questionable it may be said to take up more room then the Water did before Glaciation But though we grant that freezing makes Water swell yet how Cold which in Weather-Glasses manifestly condences the Air should expand either the Water or the intercepted Air so forcibly as to perform such things as we have newly related will yet remain a Problem Experiment 39. WE took an Oval Glass clear and least it should break pretty strong with a short Neck at the obtuser end through this Neck we thrust almost to the bottom a Pipe of Glass which was closely Cemented to the newly mention'd Neck the upper part of which Pipe was drawn in some places more slender then a Crows Quill that the changes of the Air in that Glass Egge might be the more conspicuous Then there was convey'd into the Glass five or six Spoonfulls of Water part of which by blowing Air into the Egge was rais'd into the above-mention'd slender part of the Pipe so that the Water was interpos'd between the external Air and that included in the Egge This Weather-glass delineated in the fourteenth Figure was so plac'd and clos'd up in the cavity of one of our small Receivers that onely the slender part of the Pipe to the heigth of four or five Inches passing thorow a hole in the Cover remain'd expos'd to the open Air. The Pump being set a work upon the Exsuction of the Air the Water in the Pipe descended about a quarter of an Inch and this upon two or three reiterated tryals which seem'd sufficiently to argue that there was no heat produc'd in the Receiver upon the Exsuction of the Air For even a little heat would probably have been discover'd by that Weather-glass since upon the bare application of my hand to the outside of the Receiver the warmth having after some time been communicated or propagated through both the Glasses and the interval betwixt them to the Imprison'd Air did so rarifie that as to inable it by pressing upon the subjacent Water to impel that in the Pipe very many times as far as it had fallen downwards upon the Exsuction of the Air. Yet shall not we conclude that in the cavity of the Receiver the cold was greater after the Exsuction of the Air then before For if it be demanded what then could cause the fore-mention'd subsiding of the Water it may be answered That probably it was the reaching of the Glass Egge which upon the Exsuction of the ambient Air was unable to resist altogether as much as formerly the pressure of the included Air and of the Atmosphere which by the intervension of the Water press'd upon its concave surface Which seem'd probable as well by what was above deliver'd in the Experiment about the breaking of the Glass by the force of the Atmosphere as by this notable Circumstance which we divers times observ'd That when by drawing the Air out of the Receiver the Water in the Pipe was subsided upon the readmission of the external Air to press against the convex surface of the Egge the Water was presently re-impell'd to its former height Which would perhaps appear less strange to Your Lordship if You had yet seen what we have heretofore taught in another Treatise concerning the Spring that may be discover'd in Glass as rigid and â—â—â—lexible a Body as it is generally esteem'd And in the mean while it may seâ—ve the turn to cause a Glass Egge to be blown exceeding thin and then having broken it try how far you can by degrees bend some narrow parts of it and how readily upon the removal of what kept it bent it will restore it self to its former state or posture But to return to our Experiment From thence it seems probable either that there succeeds no Body in the room of the Air drawn out of our Receiver or that it is not every Matter that is subtle enough readily to pass through the Pores of Glass that is always agitated enough to produce Heat where ever it is plentifully found So that if no Vacuum be to be admitted this Experiment seems to invite us to allow a great disparity either as to bulk or as to agitation or as to both betwixt some parts of the Etherial Substance and those that are wont here below to produce Heat and Fire We try'd also what Operation the drawing out of the Air would have upon Camphire that being a Body which though not a Liquor consists of such Volatile or Fugitive parts that without any greater agitation then that of the open Air it self they will copiously flie away But we found not that even this loose Body was sensibly alter'd by the Exsuction of the ambient Air. Experiment 40. IT may seem well worth trying whether or no in our exhausted Glass the want of an ambient Body of the wonted thicness of Air would disable even light and little Animals as Bees and other winged Insects to flie But though we easily foresaw how difficult it would be to make such an Experiment yet not to omit our endeavors we procur'd a large Flesh-fly which we convey'd into a small Receiver We also another time shut into a great Receiver a Humming Bee that appear'd strong and lively though we had rather have made the tryal with a Butter-fly if the cold Season would have permitted