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
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
laid upon the commissures of the stopple and hole to be made in the Receiver the external Air might be hindred from insinuating it self between them into the Vessel we caus'd several such Glasses as you will finde describ'd a little lower to be blown at the Glass-house and though we could not get the Work-men to blow any of them so large or of so convenient a shape as we would fain have had yet finding one to be tolerably fit and less unfit then any of the rest we were content to make use of it in that Engine Of which I suppose you by this time expect the Description in order to the Recital of the Phaenomena exhibited by it To give your Lordship then in the first place some account of the Engine it self It consists of two principal parts a glass Vessel and a Pump to draw the Air out of it The former of these which we with the Glass-men shall often call a Receiver for its affinity to the large Vessels of that name used by Chymists consists of a Glass with a wide hole at the top of a cover to that hole and of a stop-cock fastned to the end of the neck at the bottom The shape of the Glass you will find express'd in the first Figure of the annexed Scheme And for the size of it it contain'd about 30 Wine Quarts each of them containing near two pound of 16 Ounces to the pound of water We should have been better pleas'd with a more capacious Vessel but the Glass-men professed themselves unable to blow a larger of such a thickness and shape as was requisite to our purpose At the very top of the Vessel A you may observe a round hole whose Diameter BC is of about four inches and whereof the Orifice is incircled with a lip of Glass almost an inch high For the making of which lip it was requisite to mention that upon the by in case your Lordship should have such another Engine made for you to have a hollow and tapering Pipe of Glass drawn out whereof the Orifice above mentioned was the Basis and then to have the cone cut off with a hot Iron within about an Inch of the Points BC. The use of the lip is to sustain the cover delineated in the second Figure where DE points out a brass Ring so cast as that it doth within and without cover the lip BC of the first Figure and is cemented on upon it with a strong and close Cement To the inward tapering Orifice of this Ring which is about three Inches over are exquisitely ground the sides of the Brass stopple FG so that the concave superficies of the one and the convex of the other may touch one another in so many places as may leave as little access as possible to the external Air And in the midst of this cover is left a hole HI of about half an inch over invironed also with a ring or socket of the same mettal and fitted likewise with a brass stopple K made in the form of the Key of a stop-cock and exactly ground into the hole HI it is to fill so as that though it be turn'd round in the cavity it possesses it will not let in the Air and yet may be put in or taken out at pleasure for uses to be hereafter mentioned In order to some of which it is perforated with a little hole 8 traversing the whole thickness of it at the lower end through which and a little brass Ring L fastned to one side no matter which of the bottom of the stopple FG a string 8 9 10 might pass to be imploy'd to move some things in the capacity of the empty'd Vessel without any where unstopping it The last thing belonging to our Receiver is the stop-cock designed in the first Figure by N. for the better fastening of which to the neck and exacter exclusion of the Air there was soder'd on to the shank of the Cock X a Plate of Tin MTUW long enough to cover the neck of the Receiver But because the cementing of this was a matter of some difficulty it will not be amiss to mention here the manner of it which was That the cavity of the tin Plate was fill'd with a melted Cement made of Pitch Rosin and Wood-ashes well incorporated and to hinder this liquid Mixture from getting into the Orifice Z of the shank X that hole was stopt with a Cork to which was fastned a string whereby it might be pull'd out of the upper Orifice of the Receiver and then the glass neck of the Receiver being well warm'd was thrust into this Cement and over the shank whereby it was effected that all the space betwixt the tin Plate and the Receiver and betwixt the internal superficies of the Receiver and the shanck of the Cock was filld with the Cement and so we have dispach'd the first and upper part of the Engine The undermost remaining part consists of a Frame and of a sucking Pump or as we formerly call'd it an Air Pump supported by it The Frame is of Wood small but very strong consisting of three legs 111 so plac'd that one side of it may stand perpendicular that the free motion of the hand may not be hindered In the midst of which frame is transversly nail'd a board 222 which may not improperly be call'd a Midriff upon which rests and to which is strongly fastned the main part of the Pump it self which is the onely thing remaining to be described The Pump consists of four parts a hollow Cylindre a Sucker a handle to move that Sucker and a valve The Cylindre was by a pattern cast of brass it is in length about 14 inches thick enough to be very strong notwithstanding the Cylindrical cavity left within it this cavity is about three inches Diameter and makes as exact a Cylindre as the Artificer was able to bore This hollow Cylindre is fitted with a sucker 4455 consisting of two parts the one 44 somewhat less in Diameter then the cavity of the Cylindre upon which is nail'd a good thick piece of tan'd shoe Leather which will go so close to the Cylindre that it will need to be very forcibly knock'd and ram'd in if at any time it be taken out which is therefore done that it may the more exactly hinder the Air from insinuating it self betwixt it and the sides of the Cylindre whereon it is to move To the midst of this former part of the Sucker is strongly fastned the other namely a thick and narrow plate of Iron 55 somewhat longer then the Cylindre one of whose edges is smooth but at the other edge it is indented as I may so speak with a row of teeth delineated in the Scheme into whose intervals are to be fitted the teeth of a small Iron nut 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 as Trades-men call it which is fastned by two staples 22 to the under side of the formerly mention'd transverse board 222 on which the Cylindre
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
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
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
flexible Plate of Silver unto which by some stroaks of a Hammer you may give a Spring and by onely heating it red hot you may make it again flexible as before These My Lord are some of the Considerations at present occurring to my thoughts by which it may be made probable that Air may be generated anew And though it be not impossible to propose Objections against these as well as against what has been represented in favor of the contrary Doctrine yet having already almost tyr'd my self and I fear more then almost tyr'd Your Lordship with so troublesome an Enquiry after the Nature of bubbles I shall willingly leave Your Lordship to judge of the Arguments alledged on either side and I should scarce have ventur'd to entertain You so long concerning such empty things as the Bubbles which have occasion'd all this Discourse but that I am willing to invite You to take notice with me of the obscurity of things or the dimness of our created Intellects which yet of late too many so far presume upon as either to Deny or Censure the Almighty and Omniscient Creator himself and to learn hence this Lesson That there are very many Things in Nature that we disdainfully over-look as obvious or despicable each of which would exercise our Understandings if not pose them too if we would but attentively enough consider it and not superficially contemplate but attempt satisfactorily to explicate the nature of it Experiment 23. SInce the writing of the twenty one and twenty second Experiments and notwithstanding all that hath been on their occasion deliver'd concerning bubbles we made some further tryals in prosecution of the same inquiry whereto they were designed We chose then amongst those Glasses which Chymists are wont to call Philosophical Eggs one that containing about nine Ounces of Water had a Neck of half an Inch in Diameter at the top and as we ghest almost an Inch at the bottom which breadth we pitch'd upon for a reason that will by and by appear then filling it with common Water to the height of about a Foot and a half so that the upper part remain'd empty we shut it into the Receiver and watch'd what would follow upon pumping which proved that a great part of the Air being drawn out the bubbles began to discover themselves at the bottom and sides of the Glass and increasing as the Air was more and more drawn away they did from time to time ascend copiously enough to the top of the Water and there quickly break but by reason that the wideness of the Glass allow'd them free passage through the Water they did not appear as in the former Experiments to make it swell The Water scarce ever rising at all above the mark affixt to its upper surface when it was put in and upon the return permitted to the outward Air and consequently the shrinking in of the remaining bubbles the Water seem'd to have lost of its first extent by the avolation of the formerly interspers'd Air. Being willing likewise to try whether distilled Water were by having been divided into minute parts and then re-united more or less dispos'd to expand it self then Water not distill'd We took out of our Laboratory some carefully distill'd Rain-water and put about two Ounces of it into a round Glass bubble with a very small Neck not exceeding the sixth part of an Inch in Diameter which we fill'd half way to the top and then convey'd it into the Receiver the issue was That though we drew out more then ordinary yet there appear'd not the least intumescence of the Water nor any ascending bubbles But suspecting that either the small quantity of the water or the Figure of the Vessel might have an interest in this odde Phaenomenon we took the lately mention'd Philosophical Egge and another not much differing from it the former we fill'd up with distill'd Rain-water to the old mark and into the latter we put a long Cylinder or Rod of solid Glass to streighten the cavity of the Neck by almost filling it up and then pouring some distilled Water into that also till it reach'd within some Fingers breadth of the top the Eggs were let down into the Receiver In this Experiment the Air was so far drawn forth before there appear'd any bubble in either of the Glasses that the disparity betwixt this and common water was manifest enough But at length when the Air was almost quite pump'd out the bubbles began to disclose themselves and to increase as the pressure of the Air in the Receiver decreas'd But whereas in the first mention'd Philosophical Egge the bubbles were very small and never able to swell the Water that we took notice of at all above the mark In the other whose Neck as we lately said was straightned and their passage obstructed great numbers of them and bigger fastned themselves to the lower end of the Glass rammer if we may so call it and gather'd in such numbers between that and the sides of the Neck that the Water swell'd about a Fingers breadth above the mark though upon the admitting of the external Air it relaps'd to the former mark or rather fell somewhat below it And although thereupon in the first nam'd Vessel all the bubbles presently dis-appear'd yet in the other we observ'd that divers remained fastned to the lower part of the Glass rammer and continued there somewhat to our wonder for above an hour after but contracted in their Dimensions Moreover having suffered the Glasses to remain above twenty four hours in the Receiver we afterwards repeated the Experiment to try what change the exsuction of the external Air would produce in the Water after the internal and latitant Air had as is above recited in great measure got away in bubbles and whether or no the Water would by standing re-admit any new particles of Air in the room of those that had forsaken it But though we exhausted the Receiver very diligently yet we scarce saw a bubble in either of the Glasses notwithstanding which we perceiv'd the Water to rise about the breadth of a Barly-corn or more in the Neck of that Glass wherein the solid Cylinder had been put The Liquor in the other Glass not sensibly swelling And lastly upon the letting in of the Air the Water in the straightned Neck soon subsided to the mark above which it had swollen which whether it ought to be ascrib'd to the same small expansion of the parts of the Water it self or to the rarifaction of some yet latitant Air broken into such small particles as to escape our observation seems not easily determinable without such further tryals as would perhaps prove tedious to be recited as well as to be made though I was content to set down those already mention'd that it might appear how requisite it is in nice Experiments to consider variety of Circumstances AFter having thus discover'd what operation the exsuction of the ambient Air had upon Water
were not above an Inch and â— half in Diameter yet the weight kept up by suction or rather supported by the Air namely the Valve the Seal and what was cast into it being sent to be weigh'd amounted to about ten of our common Pounds consisting of sixteen Ounces apiece So that we doubted not but that had the Experiment been made with favorable Circumstances the Air endeavoring to press in at the Orifice of the Stop-cock would have kept a very much greater weight from falling out of it I say the Air because we found by tryal purposely made that neither the imperfect contact of the Valve and the Stop-cock nor the Diachylon that was employ'd to fill up the little Crannies left betwixt them were considerable in this Experiment by which may among other things appear that I did not without cause in the above-nam'd Discourse touching Fluidity and Firmness ascribe a great force ev'n to such Pillars of Air as may be suppos'd to begin at the top of the Atmosphere and recoyling from the ground to terminate on the Bodies on which they press since in the present Experiment such a weight was supported by so slender a Cylinder of Air rebounding from the Earth to the Valve whereon â—t did bear Experiment 33. BUt in regard we have not yet been able to empty so great a Vessel as our Receiver so well as we can the Cylinder it self our Pump alone may afford us a nobler instance of the force of the Air we live in insomuch that by help of this part of our Engine we may give a pretty near ghess at the strength of the Atmosphere computed as a weight And the way may be this First the Sucker being brought to move easily up and down the Cylinder is to be impell'd to the top of it Then the Receiver must be taken off from the Pump that the upper Orifice of the Cylinder remaining open the Air may freely succeed the Sucker and therefore readily yield to its motion downward This done there must be fasten'd to one of the Iron Teeth of the Sucker such a weight as may just suffice to draw it to the bottom of the Cylinder And having thus examin'd what weight is necessâ—ry to draw down the Sucker when the Atmosphere makes no other then the ordinary resistance of the Air against its descent the Sucker must be again forc'd to the top of the Cylinder whose upper Orifice must now be exactly closed and then the first weight remaining we easily may by hanging a Scale to the above-metion'd Iron that makes part of the Sucker cast in known weights so long till in spight of the reluctancy of the Atmostphere the Sucker be drawn down For to these weights in the Scale that of the Scale it self being added the sum will give us the weight of a Column of Air equal in Diameter to the Sucker or to the cavity of the Cylinder and in length to the heighth of the Atmosphere According to this method we did since the writing of the last Experiment attempt to measure the pressure of the Atmosphere but found it more difficult then we expected to perform it with any accurateness for though by the help of the Manubrium the Sucker moved up and down with so much ease that one would have thought that both its convex surface and the concave one of the Cylinder were exquisitely smooth as it were slippery yet when the Sucker came to be moved onely with a dead weight or pressure that was not like the force of him that pump'd intended as occasion required we found that the little rufnesses or other inequalities and perhaps too the unequal pressure of the Leather against the cavity of the Cylinder were able now and then to put a stop to the descent or ascent of the Sucker though a very little external help would easily surmount that impediâ—ment and then the Sucker would for a while continue its formerly interrupted motion though that assistance were withdrawn But this discouragement did not deterre us from prosecuting our Experiment and endeavoring by a careful trial to make it as instructive as we could We found then that a Leaden Weight of 28 pounds each consisting of sixteen Ounces being fastned to one of the teeth of the Sucker drew it down slowly enough when the upper Orifice of the Cylinder was left open though by the help of Oyl and Water and by the frequent moving the Sucker up and down with the Manubrium its motion in the Cylinder had been before purposely facilitated This done the upper Orifice of the Cylinder was very carefully and closely stopp'd the Valve being likewise shut with its wonted Stopple well oyl'd after the Sucker had been again impell'd up to the top of the Cylinder Then to the precedent twenty eight pound we added a hundred and twelve pounds more which forcing down the Sucker though but leisurely we took off the twenty eight pound weight and being unable to procure just such weights as we would have had we hung on instead of it one of fourteen pound but found that with the rest unable to carry down the Sucker And to satisfie our selves and the Spectators that it was the resistance of the ambient Air that hinder'd the descent of so great a weight after that we had try'd that upon unstopping the Valve and thereby opening an access to the external Air the Sucker would be immediately drawn down After this I say we made this further Experiment That having by a Man's strength forcibly depress'd the Sucker to the bottom of the Cylinder and then fastned weights to the above-named Iron that makes part of that Sucker the pressure of the external Air finding little or nothing in the cavity of the evacuated Cylinder to resist it did presently begin to impell the Sucker with the weights that clogg'd it towards the upper part of the Cylinder till some such accidental Impediment as we formerly mention'd check'd its course and when that rub which easily might be was taken out of the way it would continue its ascent to the top to the no small wonder of those By-standers that could not comprehend how such a weight could ascend as it were of it self that is without any visible force or so much as Suction to lift it up And indeed it is very considerable that though possibly there might remain some particles of Air in the Cylinder after the drawing down of the Sucker yet the pressure of a Cylinder of the Atmosphere somewhat less then three Inches in Diameter for as it was said in the description of our Engine the cavity of the Cylinder was no broader was able uncompress'd not only to sustain but even to drive up a weight of an hundred and odde pounds for besides the weight of the whole Sucker it self which amounts to some pounds the weights annexed to it made up a hundred and three pounds besides an Iron Bar that by conjecture weighed two pounds more and yet all
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
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
secundines may live a good while without a Respiration but in case after having once begun to breath its respiration be stoppâ—d it will presently die We are far from pretending to solve so hard a Problem but this we try'd in relation to it We took a Bitch that was said to be almost ready to whelp and having caus'd her to be hang'd we presently open'd her Abdomen and found four Puppeys in her Womb one of these we took out and having freed him from the Teguments thâ—â— involv'd him and from the Liquor he swam in we observ'd that he quickly open'd his Mouth very wide mov'd his Tongue and exercis'd Respiration then we open'd both his Abdomen and his Chest and cut assunder the Diaphragme notwithstanding which he seemâ—d often to endeavor Respiring and mov'd in a notable manner both the Intercostal Muscles part of the Diaphragme the Mouth and the Tongue But that which we mention this Puppy for was this That being desirous to try whether the other yong ones that had not yet breath'd at all would long survive this or no we took them also out of the Womb and having open'd them found none of them so much alive as to have any perceptible motion in his heart whereas the heart of that Puppy which had once enjoy'd the benefit of Respiration continu'd beating so long that we our selves observ'd the Auricle to beat after five or six hours and a Servant that staid up and watch'd it after we were gone to Bed affirm'd That he saw the Pulsation continue about two hours longer I shall leave it to others to make Reflections upon this Observation compar'd with Dr. Harvey's Problem It is much doubted whether Fishes breath under Water and we shall not take upon us as yet to determine the Question either way because we have not yet been able to procure little Fishes alive to make Experiments upon That such as are not Setaceous for such manifestly breath have not Respiration properly so call'd such as is exercis'd by four footed Beasts and Birds may be argu'd from their having but one cavity in their Hearts from their want of Lungs whence they are observ'd to be Mute unless we say what is not altogether absurd That their Gills seem somewhat Analogous as to their use to Lungs But that on the other side Air is necessary to the Lives even of Fishes and that therefore 't is probable they have some obscure kinde of Respiration seems manifest by two or three Observations and Experiments mention'd by divers Authors who tell us That Fishes soon die in Ponds and Glasses quite fill'd with Water if the one be so frozen over and the other so closely stopp'd that the Fishes cannot enjoy the benefit of the Air if we allow them to be true But because these Relations are not wont to be deliver'd by Writers upon their own Knowledge as I shall not reject them so I dare not build upon them till I have opportunity to examine them by experience In the mean time we will adde That our Engine has taught us two things that may illustrate the matter in hand The one That there is wont to lurk in Water many little parcels of interspers'd Air whereof it seems not impossible that Fishes may make some use either by separating it when they strain the Water thorow their Gills or by some other way The other what may be collected from the following Experiment We took a large Eele being able to procure no other Fish alive and removing it out of the Vessel of Water wherein it was brought us into our great Receiver we caus'd the Air to be pump'd out and observ'd That the Eele after some motion to and fro in the Glass seem'd somewhat dis-compos'd and that when we had prosecuted the Exsuction of the Air somewhat obstinately she turn'd up her Belly as dying Fishes are wont to do and from thence-forward lay altogether moveless just as if she were stark dead and though I did not think her so yet the continuing in that Posture even after the Cover of the Receiver was taken off whereby the Air was let in I shoulâ— have been of the Opinion of the By standers if the Diffidence I am wont to exercise in trying Experiments especially such as are not usual had not invited me to take the Fish out of the Receiver upon which she shew'd her self by her vivid motions as much alive as before But that is most strange which we observ'd of a great gâ—ay House Snail as they call it which being closâ—d up in one of our small Receivers did not onely not fall down from the side of the Glass upon the drawing-out of the Air For that may be ascrib'd to the tenacity of the Liquor wherewith Sâ—â—il use to stick themselves even to the smoothest Bodies but was not so much as depriv'd of progressive motion by the recess of the Air Though except this Snail we never put any living Creature into our Receiver whom it did not either kill or at least reduce to seem ready to dye But as we shall not here examine what interest the glutinous and uneasily dissipable Nature of the Juices of Snails may have on this event so whether this escape of our Eele be to be ascrib'd to the particular and vivacious Nature of this sort of Fishes or to this That the Air is not indeed necessary to the life of Fishes or finally to this That though these Animals need some Air yet they need so little that that which could not be drawn out of the Receiver might at least for a while suffice them we will not now determine Nor are we at leisure to examine that Paradox of Hippocrates which some Learned Physitians have of late reviv'd namely That the Foetus respires in the Womb For on the one side it seems very difficult to conceive how Air should traverse the Body of the Mother and the Teguments of the Childe And since Nature has in new-born Babes contriv'd peculiar and temporary Vessels that the Blood may circulate thorow other Passages then it is wont to do in the same Individuals when they come to have the free use of their Lungs it seems unlikely thâ—t Infants in the Womb do properly respire But then since our Experiments have manifested That almost all kinde of Liquors do as well as Water abound with interspers'd Corpuscles of Air it seems not altogether absurd to say That when the Foetus is grown big he may especially the upper part of the involving Amnios being destitute of Liquor and fill'd onely with an halituous Substance exercise some obscure Respiration especially since 't is not as many wise Men think it a Fable That Children have been heard to cry in the Mothers Womb. For though it happens exceeding rarely yet sometimes it has been observ'd And I know a young Lady whose Friends when she was some Years since with Childe complain'd to me That she was several times much frighted with the Cryes of her Infant
themselves such then it was whilst the wonted pressure of the Air continued unremoved It may indeed be suspected that those vast numerous Bubbles proceeded not from the action of the Menstruum upon the Corall but from the suddain emersion of those many little parcels of air that as we formerly observd are wont to be dispers'd in liquors without excluding Spirit of Vinegar but having had this suspition before we tryd the Experiment we convey'd our distill'd Vinager alone into the Receiver and kept it awhile there to free it from its Bubbles which were but very small before ever we put the Corall into it It may be suspected likewise that the agitation of the Liqour necessary following upon the shaking of the Glass by pumping might occasion the recited Ebullition but upon tryal made there appear'd not any notable change in the liquor or its operation though the containing Vessel were shaken provided no Air were suck'd out of it The former Experiment was another time tryd in another small Receiver with Coral grosly poudred and the success was very much alike scarce differing in any thing but that the Coral being reduc'd to smaller parts upon the ebullition of the liquor so many little lumps of Coral would be carryed Boy'd up by the emerging Bubbles as sometimes to darken the Viol though the same Coralline Corpuscles would be let fall again upon the letting in of the Air. Something also we try'd in our great Receiver concerning the solution of Metals in Aqua fortis and other Corrosive Liquors but partly the stink and partly some accidents kept us from observing any thing peculiar remarkable about those Solutions One thing we must not omit that when the Spirit of Vinager was boiling upon the Coral we took off the Cover of the Receiver and took out the Viol but could not finde that notwithstanding so very late an Ebullition the Liquor had any heat great enough to be at all sensible to our hands Experiment 43. WE will now subjoyn an Experiment which if the former did not lessen the wonder of it would probably appear very strange to Your Lordship as it did to the first Spectators of it The Experiment was this We caus'd Water to be boyl'd a pretty while that by the heat it might be freed from the latitant Air so often already taken notice of in common Water Then almost filling with it a Glass Viol capable of containing near four Ounces of that Liquor we convey'd it whil'st the Water was yet hot into one of our small Receivers big enough to hold about a pound of Water and having luted on the Cover we caus'd the Air to be drawn out Upon the two first Exsuctions there scarce appear'd any change in the Liquor nor was there any notable alteration made by the third but at the fourth and afterwards the Water appear'd to boyl in the Viol as if it had stood over a very quick Fire for the Bubbles were much greater then are usually found upon the Ebullition of very much more Water then was contain'd in our Viol. And this Effervescence was so great in the upper part of the Water that the Liquor boyling over the top of the Neck a pretty deal of it ran down into the Receiver and sometimes continued though more languidly boyling there Prosecuting this Experiment we observ'd that sometimes after the first Ebullition we were reduc'd to make divers Exsuctions of the Air before the Liquor would be brought to boyl again But at other times as often as the Key was turn'd to let the Air pass from the Receiver into the Pump the Effervescence would begin afresh though the Pump were ply'd for a pretty while together which seem'd to argue that the boyling of the Water proceeded from hence That upon the withdrawing the pressure of the incumbent Air either the Fiery Corpuscles or rather the Vapors agitated by the heat in the Water which last what we have formerly noted touching the rarefied Water of an Aeolipile manifest to be capable of an Elastical Power were permitted to expand themselves mightily in the evacuated Receiver and did in their tumultuous Dilatio lift up as the Air is wont to do the uppermost part of the Water and turning it into Bubbles made the Water appear boiling This conjecture was further confirm'd by these additional Circumstances First The Effervescence was confin'd to the upper part of the Water the lower remaining quiet unless the Liquor were but shallow Next although sometimes as is already noted the Ebullition began again after it had ceas'd a pretty while which seem'd to infer That some concurrent cause whatever that were did a little Modifie the operation of heat yet when the water in the Viol could by no pumping be brought to boil any more the self-same Water being in the very same Viol warm'd again and reconvey'd into the Pneumatical Glass was quickly brought to boyl afresh and that vehemently and long enough not to mention that a new parcel taken out of the same parcel of the boyled Water with the former and put in cold could by no pumping be brought to the least shew of Effervescence Besides having try'd this Experiment in hot Sallet Oyl being a much more tenacious Liquor and requiring a stronger heat to make it boil could not be brought to an Effervescence in our Reciver whereas the Chymical Oyl of Turpentine being thinner and more volatile was presently made to boyl up till it reach'd four or five times its former height in the Viol in whose bottom it lay and continuâ—d boyling till it was almost reduc'd to be but luke-warm Wine also being a more thin and spirituous Liquor then Water being convey'd in hot instead of the Oyl did as I remember at the very first Exsuction begin to boyl so vehemently that in a short time that the Pump was kept moving four parts of five by our ghess boyl'd over out of the Viol though it had a pretty long Neck On which occasion we will adde that even the Water it self near one half would sometimes boyl over into the Receiver before it became luke-warm And it was also remarkable that once when the Air had been drawn out the Liquor did upon a single Exsuction boyl so long with prodigiously vast Bubbles that the Effervescence lasted almost as long as was requisite for the rehearsing of a Pater Noster Now the Experiment having been try'd more then once and found to succeed as to the main seems much to countenance the conjecture we made at the beginning of this Letter where we told your Lordship That perhaps the pressure of the Air might have an interest in more Phaenomena then men have hitherto thought For as we had not then made this Experiment so now we have made it it seems to teach That the Air by its stronger or weaker pressure may very much Modifie as the School-men speak divers of the Operations of that vehement and tumultuous Agitation of the small parts of Bodies