TRACTS: CONTAINING 

I SUSPICIONS about some Hidden Qualities of the AIR; with an Appendix touching CELESTIAL MAGNETS, and some other Particulars.  
II. ANIMADVERSIONS upon Mr. Hobbes' PROBLEMATA De VACUO.  
III. A DISCOURSE of the CAUSE of Attraction by SUCTION.    
By the Honourable ROBERT boil, Esq Fellow of the ROYAL SOCIETY.  
LONDON, Printed by W.G. and are to be Sold by M. Pitt, at the Angel against the Little North Door of St. Paul's Church. 1674.   

Preface.  
AMong other Papers that I designed to contribute towards the Natural History of the Air, I began some years ago to set down a Collection of some new or less heeded Observations and Experiments relating to the Causes and Effects of Changes in the Air, which I referred to several Heads, as to the Airs Heat, Coldness, Moisture, Dryness, Diaphaneity, Opacity, Consistence, several Saltnesses and other Titles; the last of which was of the Occult Qualities of the Air, supposing there be any such. And though afterwards I was, by Sickness and other Impediments, diverted from proceeding in that Collection, and induced to lay aside some of the Observations I had provided, and employ in other Treatises such as were proper to them; yet as to the Title that contained Suspicions about some Hidden Qualities of the Air, the possibility, if not likelihood, that either the Matters of fact, or the Intimations delivered in them, might afford hints not useless to the Sagacious and Inquisitive, persuaded me to let it escape the Fate of its Companions, though possibly, if I had more consulted my own Reputation, I should least of all have suffered this Title to appear, there being none of the rest, that was not less conjectural. But it being thought unfit, that any thing should perish, that related to so considerable and uncommon a Subject, as that of this Title, I was content to cast the collected Experiments into the following Essay for the Reasons expressed at the beginning and close of the ensuing Paper. Which, 'twas hoped, may be the better understood, and less liable to have its Design mistaken, by being ushered in by this Advertisement about the occasion of it.   

ERRATA.  
IN the first Tract, pag. 41. l. 4. read Halicarnasseus.  
In the Tract of the Cause of Suction, p. 14. l. 4. r. 33½ for 36½.   

SUSPICIONS ABOUT Some Hidden QUALITIES in the AIR.  
BEsides the four first Qualities of the Air, (Heat, Cold, Dryness and Moisture) that are known even to the Vulgar; and those more unobvious, that Philosophers and Chemists have discovered, such as Gravity, Springiness, the power of Refracting the beams of Light; etc. I have often suspected, that there may be in the Air some yet more latent Qualities or Powers differing enough from all these, and principally due to the Substantial Parts or Ingredients, whereof it consists. And to this conjecture I have been led, partly (though not only or perhaps chiefly) by considering the Constitution of that Air we live and breath in, which, to avoid ambiguities, I elsewhere call Atmospherical Air. For this is not, as many imagine, a Simple and Elementary Body, but a confused Aggregate of Effluviums from such differing Bodies, that, though they all agree in constituting, by their minuteness and various motions, one great mass of Fluid matter, yet perhaps there is scarce a more heterogeneous Body in the world.  
And as by Air I understand not (as the Peripatetics are wont to do) a mere Elementary Body; so, when I speak of the Qualities of the Air, I would not be thought to mean such naked and abstracted Being's (as the Schools often tell us of,) but such as they call Qualities in concreto, namely Corpuscles endued with Qualities, or capable of producing them in the Subjects they invade and abound in.  
I have elsewhere shown it to be highly probable, that, 
In a Paper above Subterraneal Steams.  besides those vapours and exhalations which by the Heat of the Sun are elevated into the Air, and there afford matter to some Meteors, as Clouds, Rain, Parhelions and Rainbows; there are, at least at some times, and in some places, store of Effluviums emitted from the Subterraneal parts of the Terrestrial Globe; and 'tis no less probable, (from what I have there and elsewhere delivered,) that in the Subterraneal Regions there are many Bodies, some fluid and some consistent, which, though of an operative nature, and like upon occasion to emit steams, seldom or never appear upon the surface of the Earth, so that many of them have not so much as names assigned them even by the Mineralists. Now among this multitude and variety of Bodies, that lie buried out of our sight, who can tell but that there may be some, if not many, of a nature very differing from those we are hitherto familiarly acquainted with; and that, as divers wonderful and peculiar operations of the Loadstone, (though a Mineral many Ages ago famous among Philosophers and Physicians,) were not discovered till of later Ages, wherein its nobler Virtues have been disclosed; so there may be other Subterraneous Bodies, that are endowed with considerable powers, which to us are yet unknown, and would, if they were known, be found very differing from those of the Fossiles we are wont to deal with?  
I also further consider, that, (as I have elsewhere endeavoured to make it probable) the Sun and Planets (to say nothing of the Fixed Stars) may have influences here below distinct from their Heat and Light. On which Supposition it seems not absurd to me to suspect, that the Subtle, but Corporeal, Emanations even of these Bodies may (sometimes at least) reach to our Air, and mingle with those of our Globe in that great receptacle or rendevouz of Celestial and Terrestrial Effluviums, the Atmosphere. And if this suspicion be not groundless, the very small knowledge we have of the structure and constitution of Globes so many thousands or hundred of thousands of miles remote from us, and the great ignorance we must be in of the nature of the particular Bodies that may be presumed to be contained in those Globes, (as Minerals and other Bodies are in the Earth,) which in many things appear of kin to those that we inhabit, (as with excellent Telescopes I have often with attention and pleasure observed, particularly in the Moon,) this great imperfection, I say, of our knowledge may keep it from being unreasonable to imagine, that some, if not many, of those Bodies and their effluxions may be of a nature quite differing from those we take notice of here about us, and consequently may operate after a very differing and peculiar manner.  
And though the chief of the Heteroclite Effluviums, that endow the Air with hidden Qualities, may probably proceed from beneath the surface of the Earth, and from the Celestial Bodies; yet I would not deny but that, especially at some times and in some places, the Air may derive multitudes of efficacious particles from its own operations, acting as a fluid Substance upon that vast number and variety of Bodies that are immediately exposed to it. For, though by reason of its great thinness, and of its being in its usual state devoid both of taste and smell, it seems wholly unfit to be a Menstruum; yet I am not sure but it may have a dissolving, or at least a consuming, power on many Bodies, especially such as are peculiarly disposed to admit its operations.  
For I consider, that the Air has a great advantage by the vast Quantity of it, that may come to work in proportion to the Bodies that are exposed to it: And I have long thought, that, in divers cases, the Quantity of a Menstruum may much more considerably compensate its want of strength, than Chemists are commonly aware of, (as there may be occasion elsewhere to exemplify.) And there are liquors, which pass for insipid, (and are therefore thought to be altogether unfit to be Solvents,) which, though they have their active parts too thinly dispersed to be able presently to make sensible Impressions upon our Organs of Tasting, yet are not quite destitute of Corpuscles fit to act as a Solvent; especially if they have time enough to make with the other parts of the Fluid such numerous and various motions, as must bring, now some of them, and then others, to hit against the Body exposed to them. Which may be illustrated by the Rust like to Verdigrease, which we have observed in Copper that has been long exposed to the Air, whose saline particles, little by little, do in tract of time fasten themselves in such numbers to the surface of the Metal as to corrode it, and produce that efflorescence coloured like Verdigrease, which you know is a factitious Body, wont to be made of the same Metal, corroded by the sharp Corpuscles of Vinegar, or of the Husks of Grapes: Besides, that by the power, which Mercury has to dissolve Gold and Silver, it appears, that it is not always necessary for the making a Fluid fit to be a Dissolvent, that it should affect the Tast. And as to those Bodies, on which the Aerial Menstruum can, though but slowly, work, the greatest quantity of it may bring it this advantage, that, whereas even the strongest Menstruums, if they bear no great proportion in bulk to the Bodies they are to work on, are easily glutted, and being unable to take up any more, are fain to leave the rest of the Body undissolved, our Aerial Menstruum bears so vast a proportion to the Bodies exposed to it, that when one portion of it has impregnated itself as much as 'tis able, there may still come fresh and fresh to work further on the remaining part of the exposed Body.  
Besides the Saline and Sulphureous particles, that, at least in some places, may (as I have elsewhere shown) impregnate the Air, and give it a greater affinity to Chemical Menstruums more strictly so called; I am not averse from thinking, that the Air, merely as a fluid Body, that consists of Corpuscles of differing sizes and solidities restlessly and very variously moved, may upon the account of these Corpuscles be still resolving, or preying upon, the particles of the Bodies that are exposed to their action. For, many of those Aerial Corpuscles, some hitting and some rubbing themselves every minute against those particles of exposed Bodies that chance to lie in their way, may well, by those numerous occursions and affrictions, strike off and carry along with them now some and then others of those particles; as you see it happens in water, which, as soft and fluid as it is, wears out such hard and solid Bodies as Stones themselves, if it often enough meet them in its passage, according to the known saying, 
Gutta cavat Lapidem non vi, sed saepe cadendo.  And though the Aerial Corpuscles be very minute, and the Bodies exposed to them oftentimes large and seemingly solid; yet this needs not make you reject our supposition, because 'tis not upon the whole Body at once, that, according to us, the Aerial Corpuscles endeavour to work, but upon the Superficial particles, which may often be more minute than those Corpuscles; as you will the more easily believe, if you first observe with a good Microscope, how many extant particles may be met with on the surface of Bodies, that to the naked Eye seem very smooth, and even of those that are polished by Art with Tripoli or Puttee; and then consider, that one of these protuberancies, being yet manifestly visible, may well be presumed to consist of a multitude of lesser particles, divers of which may very well be as minute as those Aerial Corpuscles, that successively hit against them, and endeavour to carry them along with themselves. And this may be illustrated by a familiar instance. For, if you take a lump of Loaf Sugar, or even of a much solider and harder Body, Sal Gemmae, and cast it into common water, though this liquor be insipid, and the motions of its corpuscles but very languid; yet these corpuscles are capable to loosen and carry off the superficial particles of Sugar or Salt, that chance to lie in their way, and fresh corpuscles of water still succeeding to work upon the remaining particles of the exposed Body that stand in their way, the whole lump is by little and little dissolved, and ceases to appear to the Eye a thing distinct from the liquor.  
Some things that have occurred to me have made me suspect, that 'tis not impossible, but that some Bodies may receive a disposition to Volatility, and consequently to pass into the Air by the action either of the Sunbeams, in the form of the Sunbeams, or of some substance that once issued out of the Sun and reached unto our Air. For, there may be certain Bodies for the most part in the form of liquors, which, though they pass off from some peculiarly disposed Bodies, may during their stay or contact produce in them a great and strange aptness to be volatilised. In favour of which conjecture, I might here allege both the effects, which the Paracelsians and Helmontians ascribe to the Alkahest of volatilizing even fixed and ponderous Bodies barely by being often abstracted from them, and some other things, which I shall now leave unmentioned, because you may find them in my Notes about Volatility and Fixity.  
But, whatever become of this Conjecture, 'tis consonant to Experience, that, either upon the above-recited accounts, or also some others, those parts of the Atmosphere, which, in a stricter sense, may be called the Air, are, at least in some places, so intermixed with particles of differing kinds, that among that great number of various sorts of them, 'tis very likely that there should be some kinds of an un-common and an unobserved nature. And I could countenance what has been said by the wasting of Odorous Bodies, and especially Camphire, and by representing, that I have observed some solid Bodies actually cold, when their superficial parts were newly taken off, to emit, though invisibly, such copious steams into the Air, as to grow continually and manifestly lighter upon the balance, so as to suffer a notable decrement of weight in a minute of an hour. But the mention I make of such things in an other paper, dissuades me from insisting on them here, where 'twill be seasonable to resume the discourse, which the mention of the Dissolving power, that may be guessed to be in the Air, has for some pages interrupted, and to tell you, that those propounded, before I entered upon the digression, are the two main Consideration à priori (as they speak) whereon I have grounded my surmise, which being proposed but as a Suspicion, I presume it will not be expected, that the Arguments à posteriori, which I shall bring to countenance it, should be more than Conjectures, much less that they should be Demonstrations. And therefore I shall venture to lay before you some few Phaenomena, which seem to be at least as probably referable to some latent Quality in the Air, as to any other cause I yet know. Upon which score such Phaenomena may be allowed to be pleaded in favour of our Suspicion, till some other certain cause of them shall be satisfactorily assigned.  
Having premised thus much to keep you from looking for stronger proofs than I think my task obliges me to give; the first Phaenomenon, I shall propose, shall be the appearing or growth of some Salts in certain Bodies, which we observed to afford them either not at all, or at lest nothing near in such plenty, or so soon, unless they be exposed to the Air. Of such a Phaenomenon as this, that is not so much as mentioned by Vulgar Philosophers, and very rarely, if at all, to be met with in the Laboratories of Chemists, you will not, I suppose, wonder, that I do not present you many Examples, and some few I am able to name. For I remember, that suspecting a solid Marchasite, hard as stone, to be fit to be made an instance for my purpose, I caused it to be broken, that the internal more shining parts might be exposed to the Air; but, though this were done in a room, where a good fire was usually kept, so that the Marchasite was not only sheltered from the rain, but kept in a dry Air, yet after a while I discovered upon the glistering parts an efflorescence of a vitriolate nature.  
And afterwards meeting with a ponderous and dark coloured Mineral, and which, at the first breaking, discovered to the Eye no appearance of any Salt, nor so much as any shining Marchasitical particles, we found nevertheless, that a good quantity of these hard and heavy Bodies, being kept exposed to the Air, even in a room that preserved them from the rain, though probably they had lain many ages entire in the hill, wherein they were found under ground; yet in not many months, by the operation of the Air upon them, they were, in great part, crumbled to powder exceeding rich in Copperas. Nay, I remember, that having for Curiosities sake, laid up some of these stones in a room, where I constantly kept fire, and in the drawer of a Cabinet, which I did not often take out to give them fresh Air, some, if not most of them, were notwithstanding ●over'd with a copious efflorescence, which by its conspicuous colour between blue and green, by its taste, and by its fitness to make in a trice an inky mixture with infusion of galls, sufficiently manifested itself to be Vitriol; whose growth by the help of the contact of the Air is the more considerable, because it is not a mere Acid Salt, but abounds in Sulphureous and Combustible parts, which I have divers times been able, by Methods elsewhere mentioned, actually to separate or obtain from common Vitriol without the addition of any combustible body, and sometimes without any additament at all. It was also uncommon, that our blackish Minerals required no longer time, nor no rain, to make them afford their Vitriolate Efflorescences: For I remember, I kept many of those Marchasites, both glittering ones and others, of which they make and sell great quantities of Vitriol at Deptford, without perceiving in them a change that came any thing near to what I have recited. And I observed those, whose trade it is to make Vitriol, to be often obliged to let their Vitriol-stones, as they call them, lie half a year, or even eighteen months, or two years exposed, not only to the open Air, but to the Rain and Sun, to be able to obtain from them their Vitriolate parts.  
That also the Earth or Ore of Alum, being robbed of its Salt, will in tract of time recover it by being exposed to the Air, we are assured by the experienced Agricola, where, having delivered the way of making Alum, he subjoins this Advertisement: Terra Aluminosa, quae in castellis diluta, postquam effluxit, superfuit egesta et coacervata quotidie, rursus magis & magis fit aluminosa, non aliter atque terra ex qua halinitrum fuit confectum, suo succo plenior fit; quare denuo in Castilia conjicitur & aquae affusae ea percolantur.  
I have likewise observed, as you also perchance have done, that some kind of Lime in old walls and moist places has gained in length of time a copious efflorescence, very much of a Nitrous Nature; as I was convinced by having obtained Saltpetre from it by barely dissolving it in common water, and evaporating the filtrated Solution: And that in calcined Vitriol, whose saline parts have been driven away by the violence of the fire, particles of fresh Salt may be found after it has lain a competent time in the Air, I shall e'er long have occasion to inform you.  
But in the mean time, (to deal ingenuously with you,) I shall freely confess to you, that, though these and the like observations have satisfied Learned men, without having been called in question, and consequently have, at least, probability enough to ground our Suspicion upon; yet I, that am more concerned for the Discovery of a Truth than the Reputation of a Paradox, propose the Argument drawn from the foregoing Observations, but as a Probationer. For it yet seems to me somewhat doubtful, whether the Salts, that appear in the forementioned cases, are really produced by the operation of the Air working as an Agent, or also concurring as an Ingredient; or whether these saline substances be not the production of some internal thing that is analagous' to a Seminal Principle, which makes in these bodies a kind of maturation of some parts, which being once ripened, and perhaps assisted by the moisture of the Air, disclose themselves in the form of saline Concretions; as in the feculent or Tartareous parts of many Wines there will in tract of time be generated or produced store of Corpuscles of a saline nature, that produce the acid taste we find in Tartar, especially that of Rhenish wine. It may also be suspected, that the formerly mentioned Salts found in Marchasites, in Nitrous and Aluminous Earth's, &c. are made by the saline particles of the like nature, that among multitudes of other kinds swim in the Air, and are attracted by the congenerous particles, that yet remain in the Terrestrial bodies, that are, as it were, the wombs of such Minerals, (as I have elsewhere shown, that Spirit of Nitre will, with fixed Nitre and some other Alkalys, compose Saltpetre;) or else, that these Aerial Salts, if I may so call them, assisted by the moisture of the Air, do soften and open, and almost corrode or dissolve the more Terrestrial Substance of these wombs, and thereby solicit out and somewhat extricate the latent Saline particles, and, by their union with them, compose those Emerging bodies that resemble Vitriol, Alum, etc.  
But not only to suggest these scruples, as if I had a mind they should but trouble you, and keep you irresolute, I shall propound something towards the removal of them; namely, that a convenient quantity of Nitrous Earth, or that other of those Substances, which you would examine, be kept in a close vessel to which the Air has not access, for at least as long time as has been observed to be sufficient to impregnate the like substance, or rather a portion of the same parcel that was chosen to be included: For, if the body, that was kept close, have either gained no Salt at all, or very much less in proportion to its bulk than that which was kept exposed, we may thence estimate, what is to be ascribed to the Air in the production of Nitre or other saline Concretions. And, because I have observed none of these bodies, that would so soon, and so manifestly, even to the eye, disclose a saline substance, as the blackish Vitriol-Ore, I lately told you I kept in a drawer of my Cabinet; I judged that a very fit subject, wherewith to try, what maturation or time, when the Air was secluded, would perform towards the deciding of our Difficulty: And accordingly having taken some fragments of it, which we had carefully freed from the adhering Vitriolate efflorescence, by whose plenty we were assured that it was very well disposed to be wrought on by the Air, we put of these fragments of differing sizes into two conveniently shaped glasses, which being Hermetically sealed were ordered to be carried away, and kept in fit places; by which mean 'twas expected, that, even without opening the glasses, we should be able easily to see by the changed colour of the superficial parts, whether any Vitriolate efflorescence were produced; but, through the negligence or mistake of those, to whom the care was recommended, the experiment was never brought to an issue; and though I afterwards got more of the Mineral, and made a second trial of the same, I have not yet been informed of the event.  
But, Sir, though, till the success of some such trial be known, I dare not too confidently pronounce about the Production or Regeneration of Salts in bodies that have been robbed of them, and ascribe it wholly to the Air; yet, when I consider the several and great effects of the Air upon divers other bodies, I think it not rash to conjecture in the mean time, that the operations of the Air may have a considerable share in these Phaenomena, and so that there may be latent Qualities in the Air, in the sense I declared above, where I told you, that, when I speak of these Qualities, I look upon them in Concreto, (as they phrase it,) together with the Substances or corporeal effluvia they reside in: And of these Aerial Qualities, taken in this sense, I shall now proceed to mention some other Instances.  
The Difficulty we find of keeping Flame and Fire alive, though but for a little time, without Air, makes me some times prone to suspect, that there may be dispersed through the rest of the Atmosphere some odd substance, either of a Solar, or Astral, or some other exotic, nature, on whose account the Air is so necessary to the subsistence of Flame; which Necessity I have found to be greater, and less dependent upon the manifest Attributes of the Air, than Naturalists seem to have observed. For I have found by trials purposely made, that a small flame of a Lamp, though fed perhaps with a subtle thin Oil, would in a large capacious glass-Receiver expire, for want of Air, ●●in a far less time than one would be●eve. And it will not much lessen the difficulty to allege, that either the gross fuliginous Smoke did in a close Vessel stifle the flame, or that the pressure of the Air is requisite to impel up the aliment into the wieck: For, to obviate these objections, I have in a large Receiver employed a very small wieck with such rectified Spirit of Wine, as would in the free Air burn totally away; and yet, when a very small Lamp, furnished (as I was saying) with a very slender wieck, was made to burn, and, filled with this liquor, was put lighted into a large Receiver, that little flame, though it emitted no visible smoke at all, would usually expire within about one minute of an hour, and, not seldom, in a less time; and this, though the wieck was not so much as singed by the flame: Nor indeed is a wieck necessary for the experiment, since highly rectified Spirit of Wine will in the free Air flame away well without it. And indeed it seems to ●●erve our wonder, what that should be in the Air, which enabling it to keep flame alive, does yet, by being consumed or depraved, so suddenly render the Air unfit to make flame subsist. And it seems by the sudden wasting or spoiling of this fine Subject, whatever it be, that the bulk of it is but very small in proportion to the Air it impregnates with its virtue. For after the extinction of the flame, the Air in the Receiver was not visibly altered, and, for aught I could perceive by the ways of judging I had then at hand, the Air retained either All, or at least far the greatest part of its Elasticity, which I take to be its most genuine and distinguishing property.  
And this undestroyed springyness of the Air seems to make the necessity of fresh Air to the Life of hot Animals, (few of which, as far as I can guests after many trials, would be able to live two minutes of an hour, if they were totally and all at once deprived of Air,) suggest a great suspicion of some vital substance, if I may so call it, diffused through the Air, whether it be a volatile Nitre, or (rather) some yet anonymous substance, sidereal or Subterraneal, but not improbably of kin to that, which I lately noted to be so necessary to the maintenance of other flames.  
I know not, whether you will think it pertinent to our present Discourse, that I observe to you, that by keeping putrifying bodies in glasses, which by Hermes his seal were secured from the contact of the external Air, I have not been able to produce any Insect or other living Creature, though sometimes I have kept Animal Substances and even Blood so included for many months, and one or two of them for a longer time; and though also these Substances had a manifest change made in their consistence whilst they remained sealed up.  
On this occasion I shall add an odd Observation, that I met with in a little Dissertation de admirandis Hungariae aquis, written by an Anonymous, but Ingenious, Nobleman of that Country, where, speaking of the native Salt that abounds in their Regions, he says, that in the chief Mine (by them called Desiensis) of Transylvania, there was, a few years before he writ, a great Oak like a huge beam dug out of the middle of the Salt; but, though it was so hard, that it would not easily be wrought upon by Iron-tools, yet being exposed to the Air out of the Mine, it became so rotten, as he expresses it, that in four days it was easy to be broken and crumbled between ones fingers. And of that corruptive or dissolutive Power of the Air near those Mines, the same Author mentions other Instances.  
Having found an Antimonial Preparation to procure Vomits, in a case where I did not at all expect it, I was afterwards curious to inquire of some Physicians and Chemists, that were of my Acquaintance, whether they had not taken notice, that Antimonium Diaphoreticum, which, as its name imports, is wont to work by sweat or transpiration, would not become vomitive, if 'twere not kept from the Air? To which one Physician, that was a Learned Man, assured me, it would, as he had found by particular trials: And the like answer has been given me by more than one. And I find, that the experienced Zwelfer himself does somewhere give a caution against letting the Air have access to these Antimonial Medicines, lest it should render them, as he says it will, in tract of time, not only Emetic, but disposed to produce heart-burnings, (as they call them,) faintings, and other bad Symptoms. And I learned by inquiry from a very Ingenious Doctor of Physic, that, having carefully prepared Antimonium Diaphoreticum, he gave many doses of it whilst it was fresh and kept stopped in a glass (without finding that in any Patient it procured so much as one vomit,) but having kept a parcel of the self same Remedy for a pretty while in a glass only covered loosely with a paper, the Medicine, vitiated by the Air, proved emetic (strongly enough) to those, who neither by Constitution, or foulness of stomach, or on any other discernible account, were more than others that had taken it disposed to vomit. By which Observations, and from what I formerly told you of the Saltpetre obtainable from Quicklime, a Man partial to the Air would be made forward to tell you, that this looks, as if either there were in the Air a substance disposed to be assimilated by all kinds of bodies, or that the Air is so vast and rich a Rendezvouz of innumerable seminal Corpuscles and other Analogous particles, that almost any body long exposed to it may there meet with particles of kin to it, and fit to repair its wrongs and losses, and restore it to its natural Condition. But without taking any further notice of this odd surmise, I will proceed to mention two or three other Phaenomena of Nature, that seem to favour the Suspicion, that there may be Secret Qualities in the Air in reference to some bodies.  
The ingenious Monsieur de Rochefort, in the handsome account he gives of the Apple or Fruit of the Tree junipa, whose juice is employed by the Indians to black their skins, that they may look the more terrible to their Enemies, observes, that, though the stain, or, as he speaks, the Tincture of this Fruit cannot be washed out with Soap, yet within nine or ten days it will vanish of itself; which would make one suspect, that there may be in the Air some secret powerful substance, that makes it a Menstruum of more efficacy than Soap itself to obliterate stains. I remember, I have seen this Fruit, but not whilst it was succulent enough to have a trial made with it; which I was therefore troubled at, because the Author does not clearly express, whether this disappearing of the tincture happens indifferently to the bodies it chances to slain, or only is observed on the skins of Men. For, as in the former Case 'twill afford an instance pertinent to our present purpose; so in the latter I should suspect, that the vanishing of the tincture may be due not so much to the operation of the Air upon it, as to the sweat and exhalations of a human body, which abounding with volatile Salt, may either destroy or carry off with them the coloured particles they meet with in their passage.  
I have sometimes, not altogether without wonder, observed the excellency of the better sort of Damasco-steel, (for I speak not of all that goes under that name,) in comparison of ordinary steel. And, besides what I have elsewhere taken notice of concerning it, there is one Phaenomenon, which though I am not sure it belongs to the latent Qualities of the Air, yet because it may well do so, and I am unwilling it should be lost, I will here tell you, that having inquired of an eminent and experienced Artificer, (whom I long since employed in some difficult Experiments,) about the properties of Damasco-steel, this honest and sober Man averred to me, that when he made Instruments of it, and gave them the true temper, which is somewhat differing from that of other Steel, he generally observed, that though, when Razors or other Instruments made of it were newly forged, they would be sometimes no whit better, and sometimes less good, than those made of other Steel; yet when they had been kept a year or two or three in the Air, though nothing else were done to improve them, they would be found much to surpass other Instruments of the same kind, and what themselves were before; in so much; that some of them have been laid aside at first, as no way answering the great expectation conceived of them, which after two or three years were found to surpass it; of which also I am now making a trial. I have several times made a substance that consists chiefly of a Metalline body, and is of a texture close enough to lie for many hours undissolved in a Corrosive Menstruum; and yet this substance, that was fixed enough to endure the being melted by the Fire without losing its colour, would, when I had purposely exposed it to the Air, be discoloured in a very short time, and have its superficial parts turned almost black.  
And this brings into my mind that very pretty Observation, that has been newly made in Italy by an ingenious Man, who took notice, that, if after the opening of a Vein the blood be kept till it be concreted, and have excluded the superficial serum, though the lower part be usually of a dark and blackish colour in comparison of the superficial parts, and therefore be counted far more feculent; yet, if the lump or clott of blood be broken, and the internal and dark coloured parts of the blood be exposed to the Air, it will after a time (for 'tis not said how long) be so wrought on by the contact of the Air, that the superficial part of the blood will appear as florid as the lately mentioned upper part (supposed to be, as it were, the flower of the blood,) did seem before. And this Observation I found to hold in the blood of some Beasts, whereon I tried it, in which I found it to succeed in much fewer minutes, than the Italian Virtuoso's Experiment on Human blood would make me expect.  
On the other side I have often prepared a Substance, whose effect appears quite contrary to this. For, though this factitious Concrete, whilst kept to the Fire or very carefully preserved from the Air, be of a red colour almost like the common opacous Bloodstone of the shops; yet, if I broke it, and left the lumps or fragments of it a little while in the Air, it would in a short time (sometimes perhaps not amounting to a quarter of an hour) it would, I say, have its superficial parts turned of a very dark colour, very little, and sometimes scarce at all, short of blackness.  
A very inquisitive Person of my acquaintance, having occasion to make, by Distillation, a Medicine of his own devising, chanced to observe this odd property in it, That at that time of the year, if it were kept stopped, it would be coagulated almost like Oil of Anniseeds in cold weather; yet, if the stopple were taken out, and so access were for a while given to the Air, it would turn to a liquor, and the vessel being again stopped, it would, though more slowly, recoagulate. The hints, that I guessed might be given by such a Phaenomenon, making me desirous to know something of it more than barely by Relation, I expressed rather a curiosity than a diffidence about it; and the Maker of it telling me, he thought, he had in a small Vial about a spoonful of this Medicine left in a neighbouring Chamber, I desired his leave to consider it myself, which Request being presently complied with, I found it, when he brought it into the Room which I stayed in, not liquid but consistent, though of but a slight and soft contexture. And having taken out the Cork, and set the Vial in a window, which (if I well remember) was open, though the Season, which was Winter, was cold, yet in a little time that I stayed talking with the Chemist, I found, that the so lately coagulated substance was almost all become fluid. And another time, when the Season was less cold, having occasion to be where the Vial was kept well stopped, and casting my Eyes on it, I perceived the included substance to be coagulated much like Oil of Anniseeds. And this substance having, as the Maker assured me, nothing at all of Mineral in it, nor any Chemical Salt, it consisting only of two simple bodies, the one of a vegetable and the other of an animal substance, distilled together, I scarce doubt but you will think with me, that these contrary operations of the Air, which seems to have a power in some Circumstances to coagulate such a body, and yet to dissolve and make it fluid when fresh and fresh parts are allowed access to it, may deserve to be further reflected on, in reference (among other things) to the opportune operations, the inspired Air may have on the consistence and motion of the circulating blood, and to the discharge of the fuliginous recrements to be separated from the blood in its passage through the Lungs.  
There are two other Phaenomena that seem favourable to our Suspicion, That there are Anonymous Substances and Qualities in the Air, which ought not to be altogether praetermitted on this occasion; though, because to speak fully of them would require far more time than I can now spare, I shall speak of them but succinctly.  
The latter of these two Phaenomena is the growth or appearing production of Metals or Minerals dug out of the Earth, and exposed to the Air. And this, though it be the last of the two, I mention first, because it seems expedient, lest it should prove too long an interruption to our Discourse, to postpone the Observations and annex them to the end of this Paper; only intimating to you now, that the caution I formerly interposed about the Regeneration of Salts in Nitrous and other Earth's, may, for greater security, be applied, mutatis mutandis, to that production of Metalline and Mineral bodies we are speaking of.  
The other of the two Phaenomena, I lately promised to mention, is afforded me by those various and odd Diseases, that at some times and in some places happen to invade and destroy numbers of Beasts, sometimes of one particular kind, and sometimes of another. Of this we have many instances in the Books of approved Authors; both Physicians and others; and I have myself observed some notable Examples of it. But yet I should not mention it as a ground of Suspicion, that there may be, in some times and places, unknown Effluvia and powers in the Air, but that I distinguish these from those Diseases of Animals, that proceed, as the Rot in Sheep often does, from the exorbitancy of the Seasons, the immoderateness of Cold, Heat, or any other manifest Quality in the Air. And you will easily perceive, that some of these Examples probably argue, that the Subterraneal parts do sometimes (especially after Earthquakes or unusual cleaving of the ground) send up into the Air peculiar kinds of venomous Exhalations, that produce new and mortal Diseases in Animals of such a species, and not in those of another, and in this or that particular place, and not elsewhere: Of which we have an eminent Instance in that odd Plague or Murrain of the year 1514, which Fernelius tells us invaded none but Cats. And even in Animals of the same species, sometimes one sort have been incomparably more obnoxious to the Plague than another; as Dionysius Halicarnaséus mentions a Plague that attacked none but Maids; whereas the Pestilence that raged in the time of Gentilis (a famed Physician) killed few Women, and scarce any but lusty Men. And so Boterus mentions a great Plague, that assaulted almost only the younger sort of persons, few past thirty years of age being attacked by it: Which last Observation has been also made by several later Physicians. To which may be added, what Learned Men of that Faculty have noted at several times concerning Plagues, that particularly invaded those of this or that Nation, though confusedly mingled with other People; as Cardan speaks of a Plague at Basil, with which only the Swissers, and not the Italians, French, or Germans, were infected. And johannes Utenhovious takes notice of a cruel Plague at Copenhagen, which, though it raged among the Danes, spared both the English, Dutch, and Germans, though they freely entered infected houses, and were not careful to shun the sick. In reciting of which Instances I would not be understood, as if I imputed these effects merely to noxious Subterraneal fumes; for I am far from denying, that the peculiar Constitutions of men's Bodies are likely to have a great interest in them: But yet it seems less probable, that the pestilent venom diffused through the Air should owe its enormous and fatal efficacy to the excess of the manifest Qualities of the Air, than to the peculiar nature of the pestilential poison sent up into the Air from under ground, which when it is by dilution or dissipation enervated, or by its progress passed beyond the Air we breath in, or rendered ineffectual by subterraneal or other Corpuscles of a contrary Quality, the Plague, which it, as a con-cause, produced, either quite ceases, or degenerates into somewhat else. But I have not time to countenance this Conjecture, much less to consider, whether some of those Diseases, that are wont to be called new, which either did begin to appear, or at least to be rise, within these two or three Centuries, as the Sudor Anglicus in the fifteenth Century, the Scurvy, and the Morbus Hungaricus, the Lues Moraviae, Novus Morbus Luneburgensis, and some others, in the last Century of all, may be in part caused by the exotic steams this Discourse treats of. But this Consideration I willingly resign to Physicians.  
And now, if the two forementioned Suspicions, the one about Subterraneal, the other about sidereal, Effluviums, shall prove to be well grounded, they may lead us to other Suspicions and further thoughts about things of no mean Consequence; three of which I shall venture to make mention of in this place.  

I. For we may hence be awakened to consider, whether divers changes of Temperature and Constitution in the Air, not only as to manifest Qualities, but as to the more latent ones, may not sometimes in part, if not chiefly, be derived from the paucity or plenty, and peculiar nature of one or both of these sorts of Esfluviums. And in particular, we find in the most approved Writers such strange Phaenomena to have several times happened in great Plagues and contagious Diseases, fomented and communicated, nay (as many eminent Physicians believed) begun, by some latent pestiferous, or other malignant, Diathesis or Constitution of the Air, as have obliged many of the Learned'st of them to have recourse to the immediate operation of the Angels, or of the Power and Wrath of God himself, or at least to some unaccountable influence of the Stars; none of the Solutions of which difficulties seems preferable to what may be gathered from our Conjecture; since of Physical Agents of which we know nothing so much, as that they are to us invisible and probably of a heteroclite nature, it need be no great wonder, that the operation should also be abstruse, and the effects uncommon. And on this occasion it may be considered, that there are clearer inducements to persuade us, that another Quality of the Atmosphere, its Gravity, may be altered by unseen Effluviums, ascending from the Subterraneous Regions of our Globe; and we have often perceived by the Mercurial Baroscope the Weight of the Air to be notably increased, when we could not perceive in the Air nor surface of Earth any cause to which we could ascribe so notable a change. And this gives me a rise to add, that I have sometimes allowed myself to doubt, whether even the Sun itself may not now and then alter the Gravity of the Atmosphere otherwise than by its Beams or Heat. And I remember, I desired some Virtuosos of my acquaintance to assist me in the inquiry, whether any of the Spots, that appear about the Sun, may not, upon their sudden dissolution, have some of their discussed and dispersed matter thrown off, as far as to our Atmosphere, and that copiously enough to produce some sensible alterations in it, at least as to Gravity.  
II. Another thing, that our two foremention'd Suspicions, if allowed of, will suggest, is, that it may not seem altogether improbable, that some bodies, we are conversant with, may have a peculiar disposition and fitness to be wrought on by, or to be associated with, some of those exotic Effluvia, that are emitted by unknown bodies lodged under ground, or that proceed from this or that Planet. For what we call Sympathies and Antipathies, depending indeed on the peculiar Textures and other Modifications of the bodies, between whom these friendships and hostilities are said to be exercised, I see not why it should be impossible, that there be a Cognation betwixt a body of a congruous or convenient Texture, (especially as to the shape and size of its Pores,) and the Effluviums of any other body, whether Subterraneal or sidereal. We see, that convex Burning-glasses, by virtue of their figure and the disposition of their pores, are fitted to be pervaded by the beams of Light and to refract them, and thereby to kindle combustible matter; and the same beams of the Sun will impart a lucidness to the Bolonian stone. And as for Subterraneal bodies, I elsewhere mention two Minerals, 
See the Experiment in the Discourse of the Determinate Nature of Effluviums.  which being prepared, (as I there intimate,) the steams of the one, ascending without adventitious Heat and wandering through the Air, will not sensibly work on other bodies; but if they meet with that which we prepared, they will immediately have an operation on it, whose effect will be both manifest and lasting.  
III. I now pass on to the other thing, that the two formerly mentioned Suspicions may suggest, which is, that if they be granted to be well founded, we may be allowed to consider, whether among the bodies we are acquainted with here below, there may not be found some, that may be Receptacles, if not also Attractives, of the sidereal, and other exotic Effluviums that rove up and down in our Air.   
Some of the Mysterious Writers about the Philosophers-stone, speak great things of the excellency of what they call their Philosophical Magnet, which, they seem to say, attracts and (in their phrase) corporifies the Universal Spirit, or (as some speak) the Spirit of the World. But these things being abstrusities, which the Writers of them professed to be written for, and to be understood only by, the Sons of Art; I, who freely acknowledge I cannot clearly apprehend them, shall leave them in their own worth as I found them, and only, for brevity sake, make use of the received word of a Magnet, which I may do in my own sense, without avowing the received Doctrine of Attraction. For by such a Magnet, as I here purpose to speak of, I mean not a body that can properly attract our foreign Effluviums; but such an one, as is fitted to detain and join with them, when by virtue of the various motions, that belong to the Air as a Fluid, they happened to accost the Magnet. Which may be illustrated by the known way of making Oil of Tartar (as the Chemists call it) per Deliquium. For, though the Spagyrists and others suppose, that the fiery Salt draws to it the Aqueous Vapours, yet indeed it does but arrest, and imbody with, such of those that wander through the Air, as chance in their passage to accost it.  
And, without receding from the Corpuscularian Principles, we may allow some of the bodies, we speak of, a greater resemblance to Magnets, than what I have been mentioning. For not only such a Magnet may upon the bare account of Adhesion by juxta-position or Contact, detain the Effluviums that would glide along it, but these may be the more firmly arrested by a kind of precipitating faculty, that the Magnet may have in reference to such Effluviums; which, if I had time, I could illustrate by some Instances; nay I dare not deny it to be possible, but that in some Circumstances of time or place one of our Magnets may, as it were, fetch in such steams as would indeed pass near it, but would not otherwise come to touch it. On which occasion I remember, I have in certain cases been able to make some bodies, not all of them Electrical, attract (as they speak) without being excited by rubbing, etc. far less light bodies, than the Effluviums we are speaking of.  
But this it may suffice to have glanced at, it not being here my purpose to meddle with the mystical Theories of the Chemists; but rather to intimate, that, without adopting or rejecting them, one may discourse like a Naturalist about Magnets of Celestial and other Emanations, that appear not to have been considered, not to say, thought of, either by the Scholastic, or even the Mechanical, Philosophers.   

OF CELESTIAL & AERIAL MAGNETS.  
IF now, upon what I have granted in the close of the past Discourse, you should urge the question further, and press me to declare, Whether, as I think it no impossible thing, that Nature should make, so I think it no unpracticable or hopeless thing, that Men should find, or Art should prepare, useful Magnets of the exotic Effluviums of the lower region of the Earth, or the upper of the World: It would much distress me to give any other answer, than that I think it extremely difficult, and not absolutely impossible; and therefore I would not discourage any curious or industrious Man from attempting to satisfy himself by Experiments, because even a seemingly slight discovery in a thing of this nature may be of no small use in the investigation of the nature of the Air, especially in some particular places, and of the Correspondency, which, by the intervention of the Air, the superficial part of the Terrestrial Globe may have both with the Subterraneal Regions of the Earth, and the Celestial ones of the Universe. Some of the things I have tried or seen relating to this discovery, I must for certain reasons leave here unmentioned, and only advertise you, that several bodies, which experience has assured us do imbibe or retain something from the Air, as some calcined Minerals, some Marchasites, some Salts, as well factitious as natural, etc. may be fit to be often exposed to it, and then weighed again, and farther diligently examined, whether that which makes the increment of weight, be a mere imbibed moisture or also somewhat else, and likewise whether it be separable from the body or not, or however have endowed it with any considerably Quality; and if you chance to meet with a good Magnet, you may then vary Experiments with it, by exposing it long to the Air in Regions differing much in Climate, or Soil, or both, by exposing it by day only, or by night, at several Seasons of the Year, in several Temperatures of the Air, at several considerable Aspects of the Stars and Planets, by making it more or less frequently part with what it has gained from the Air; and in short, by having regard to variety of Circumstances, which your Curiosity and Sagacity may suggest. For, by thus diversifying the Experiment many ways, you may perhaps, by one or other of them, make some unexpected and yet important discovery of what Effluviums the Air, in particular places and times, abounds with, or wants, and perchance too, of some correspondency between the Terrestrial and Etherial Globes of the World.  
I shall neither be surprised nor quarrel with you, if you tell me, that these are extravagant thoughts; but if I had been fortunate in preserving all, that Trial, Observation, or other productions of some Curiosity, I once had for such Inquiries, procured me, you would not perhaps think me so very extravagant. But though I must not here make any further mention of them, and shall only take notice of one body, namely VITRIOL, whether crude, or unripe, and (as Chemists speak) embrionated, or Spagyrically prepared; yet some Phaenomena of these Vitriolate Substances may for the present, I hope, somewhat moderate your censure for my putting you upon Observations that I fear you yourself will judge unpromising, and less favourable persons than you would think fantastical. And to let you see by a pregnant Instance, that the Air may not only have a Notable operation upon Vitriol, and that, after a strong fire could work no farther on it, but that this operation was considerably diversified by Circumstances; I shall begin what I have to allege, with what the experienced Zwelfer occasionally observed, and relates to usher in a caution about a Chemical Preparation of Vitriol: For, having informed his Reader, that the Colcothar, that is made by a strong Distillation, is not corrosive, he denies, that, (to use his own words) statim à Distillatione Sal ex eodem, affusâ aquâ, elici queat; sed tum prius, (continues he) ubi aliquandiu aeri expositum fuerit; tunc enim sal praebet quandoque candidum, quandoque purpureum, aspectu pulcherrimum, quod aliquando in copia acquisivi, & penes me asservo, quandoque etiam Nitrosum.  
Which Testimony of this candid Spagyrist has much the more weight with me, because I find, what he affirms of the Saltlesness of newly and strongly calcined Vitriol to be very agreeable to some of my Experiments about Colcothar of blue (v●nereal) Vitriol; which Salt or Mineral (I mean Vitriol) is so odd a Concrete, that I have thought fit more than once to recommend the making Experiments about it to several Curious Persons, that had better opportunity to continue them than I, whose residence was not so fixed. And I remember, that one of these, a Person industrious and versed in Chemical Operations, gave me this account, that not only he had differing kinds of Salts from Colcothar exposed to the Air for many months, and robbed at convenient times of what it had acquired, but that in tract of time he found it so altered, that he obtained from it a pretty quantity of true running Mercury.  
And now, to resume and conclude what I was saying about Colcothar, there are two or three things I would propose to be observed by you, or any Virtuoso that would assist me in these trials about this odd Calcinatum, (for to call it Terrae damnata, were to injure it.)  
The first is, to take notice of ●ome Circumstances that most Observers would overlook; such as (besides the Nature of the Soil) the Temperature of the Air, the Month of the Year, and the Winds, the weight of the Atmosphere, the Spots of the Sun, if any be, the Moon's Age, and her Place in the Zodiac, and the principal Aspects of the Planets, and the other chief Stars. For, though it be a boldness to affirm, that any, or perhaps all of these together, will have any interest in the production of the Salt or other Substance, to be made or disclosed in the Colcothar; yet in things new and exorbitant, it may be sometimes rash and peremptory to deny, even such things as cannot, without rashness, be positively asserted; and in our case the small trouble of taking notice of Circumstances will be richly paid by the least discovery made in things so abstruse and considerable. And as we cannot yet knowingly pronounce, so much as negatively, whether the Libration of the Moon and the Motion of the Sun (and perhaps of some of the other Planets) about their own Centres, and consequently their obverting several parts of their bodies to us, may have an operation upon our Atmosphere; so, for aught I know, there may be in those vast internal parts of the Earth, whose thin crust only has been here and there dug into by Men, considerable Masses of Matter, that may have periodical Revolutions, or Accensions, or Estuations, or Fermentations, or, in short, some other notable Commotions, whose Effluvia and Effects may have operations, yet unobserved, on the Atmosphere and on some particular bodies exposed to it; though these periods may be perhaps either altogether irregular, or have some kind of regularity differing from what one would expect. As we see, that the Sea has those grand Intumescencies, we call Springtides, not every day, nor at any constant day of the month or week, but about the Full and New Moon; and these Springtides are most notably heightened, not every month, but twice a year, at or about the Vernal and Autumnal Equinoxes; which Observations have not been near so ancient and known, as the daily Ebbing and Flowing of the Sea. The Etestans of the Ancients I shall not now insist on, nor the Observations that I think I elsewhere mentioned of the Elder Inhabitants of the Caribe-Islands, who, when the Europeans first resorted thither, were wont to have Hurricanes but once in seven years; afterwards they were molested with them but once in three years; and of late they are troubled with them almost every year. And a Physician that lived there told me, that he had scarce ever observed them to come but within the compass of two months joining to one another. In which Instances, and divers others that may be noted of what changes happened to great Quantities of Matter, Nature seems to affect something of periodical, but not in a way that appears to us, regular.  
One may add on this occasion that memorable passage related by the Learned Varenius of those Hot Springs in Germany, 
Varenius. Lib. 1. Geograph. Vnivers. Therm omnes forè qu●● novimus fiu● cess●tione f●uunt exceptis Piperini● Germania, etc.  that he calls Thermae Peperinae, of which he affirms in more than one place, that they have this peculiarity, that they annually begin and cease to flow at certain times; the former about the third day of May, and the latter near the middle of September, at which time they are wont to rest till the following Spring. But though, for aught I know, our Geographers Observation will hold in hot Springs; yet it must not be extended to all, at least, if we admit that which is related by the accurate johannes de Laet, 
Amer. Lib. V. cap. 7.  (I suppose out of Ximenes, or the famous Conqueror of Mexico, Cortes,) who tells us, that in the Mexican Province, Xilotepec, Fons celebratur, qui quatuor continuit annis scaturit, deinde quatuor sequentibu● deficit, & rursus ad priorem modum erumpit, &, quod mirabile, pluviis diebus, parciùs, quum sudum est tempus & aridum, copiosiùs, exuberat.  
But this is not a place to enlarge upon the grounds of my suspecting, there may be some periodical Motions and Commotions within the Terrestrial Globe; what has been mentioned being only to invite you to take notice of Circumstances in your Observations of Colcothar, some of which may, with the more show of probability, be kept exposed for a long time, because that Bars of Windows and other erected Irons I have found to acquire in tract of time from the Effluvia of the Earth a settled Magnetism.  
The other main thing I would recommend, is, that notice be taken not only of the kind of Vitriol, the Colcothar is made of; (for I generally used blue Danzig Vitriol) as Martial Vitriol, Hungarian Vitriol, Roman Vitriol, etc. to which I have, for Curiosity, added Vitriol made by ourselves of the Solution of the more saline parts of Marchasites in water, without the usual additament of Iron, or Copper; but also, to what degree the calcination is made, and how far the calcined Matter is freed from the Salt by water. For these Circumstances, at least in some places, may be of moment, and perhaps may afford us good hints of the Constitution of the Atmosphere in particular parts, as well as of the best preparation of Colcothar for detaining the exotic Effluviums. And I would the rather have Experiments tried again in other places with Colcothar not calcined to the utmost, nor yet so exquisitely edulcorated, but that some saline particles should be left in it for future increase; because I have more than once purposely tried in vain, that the Caput Mortuum of blue Vitriol, whereof the Oil and other parts had been driven off with a violent and lasting fire, would not, when fresh, impart any saltness to the water; nor do I think, that out of some ounces purposely edulcorated I obtained one grain of Salt. And this saltless Colcothar being exposed, some by me, and some by a Friend that had conveniency in another place not far off, to the Air, some for many weeks and some for divers months, we did not find it to have manifestly increased in weight, or to have acquired any sensible saltness, which, supposing the Vitriol to have nothing extraordinary, gave me the stronger suspicion of some peculiarity in the Air of that part of London, where the Trials had been made, at least during those times wherein we made them; because not only former experience, made here in England, had assured me, that some Colcothars will gain no despicable accession of weight by being exposed to the Air; but accidentally complaining of my lately mentioned disappointment to an ingenious Traveller, that had, in divers Countries, been curious to examine their Vitriols, he assured me, that, though he usually dulcified his Colcothar very well, yet within four or five weeks he found it considerably impregnated by the Air 'twas exposed to.  
It remains, that I add one intimation more about Vitriol, which is, that I have found it to have so great a correspondency with the Air, that it would not be amiss to try, not only Colcothar of differing Vitriols (whether barely made the common way, or without any Metalline addition to the Vitriol Stones or Ore,) but other Preparations of Vitriol too, such as exposing Vitriol, only calcined to whiteness by the Sunbeams, or further to an higher colour by a gentle Heat, or throughly calcined, and then impregnated with a little of its own Oil. For such Vitriolate Substances as these, the Air may work upon, nay even liquid Preparations of Vitriol may be peculiarly affected by the Air, and thereby perhaps be useful to discover the present constitution, or foretell some approaching changes of it. Of the use of which conjecture, namely the peculiar action of the Air on some Vitriolate Liquors, I remember I showed some Virtuosos a new Instance in an Experiment, whereof this was the Sum:  
[I elsewhere mention a Composition that I devised, to make with Sublimate, Copper, and Spirit of Salt, a Liquor of a Green exceeding lovely. But in the description of it I mentioned not (having no need to do it there) a circumstance as odd as the liquor itself was grateful. For the Air has so much interest in the production of this green, that when you have made the Solution of the Copper and Mercury with the Spirit of Salt, that Solution will not be green, nor so much as greenish, as long as you keep it stopped in the bolt-head, or such like glass wherein 'tis made. But if you pour it out into a Vial, which, by not being stopped, leaves it exposed to the Air, it will after a while sooner or later attain that delightful green that so much endears it to the Beholder's Eye. This appeared so odd an Experiment to the Virtuosos, to whom I first related it, that those that could not guests by what means I attained it, could scarce believe it. But that troubled not me, who, to satisfy myself not only of the Truth of the Experiment, but that 'twas not so contingent as many others, repeated it several times, and found the Solution, till the Air made it flourish, to be of a muddy reddish colour quite differing from green. So that I remember, that having once kept some of the liquor in the same glass-egg, wherein the Solution had been made, it looked like very dirty water, whilst the other part of the same Solution, having been exposed to the Air, emulated the colour of an Emerald. In which change 'tis remarkable, that to clarify this liquor and give it a transparent greeness, I perceived not, that any precipitation of foul matter was made to which the alteration could be ascribed; and yet to make it the more probable that this change proceeded not from a subsidence made of some opacating matter effected by some days rest, I kept some of the Solution sealed up in a fine Vial several months, without finding it at the end of that time other than a dark or muddy liquor, which, in short time, it ceased to be, when, the Hermetic Seal being broken off, the Air was permitted to work upon it. And this I further observed in our various Experiments on this liquor, that, according to the quality of the matter and other Circumstances, the greeness was not attained to but at certain periods of time, now and then disclosing itself within two or three days, and sometimes not before nine or ten.]  
With how little Confidence of success Trials, that have the aims of these I have been speaking of, are to be attempted, not only consideration but experience have made me sensible. But yet I would not discourage men's Curiosity from venturing even upon slight probabilities, where the Nobleness of the Subjects and Scope may make even small attainments very desirable. And till trial have been made on occasions of great moment, 'tis not easy to be satisfied, that Men have not been wanting to themselves; which I shall only illustrate by proposing, what, I presume, will not need that I should make an application of it. Those adventurous Navigators, that have made Voyages for Discovery in unknown Seas, when they first discerned something obscure near the Horizon at a great distance off, have often doubted, whether what they had so imperfect a sight of, were a Cloud, or an Island, or a Mountain: But though sometimes it were more likely to be the former, as that which more frequently occurred, than the latter; yet they judged it advisable to steer towards it, till they had a clearer prospect of it: For if it were a deluding Meteor, they would not however sustain so great a loss in that of a little labour, as, in case it were a Country, they would in the loss of what might prove a rich Discovery: And if they desisted too soon from their Curiosity, they could not rationally satisfy themselves, whether they slighted a Cloud or neglected a Country.  
FINIS.   

OBSERVATIONS ABOUT THE GROWTH OF METALS in their ORE Exposed to the AIR.  
By the Honourable ROBERT boil, Fellow of the Royal Society.  
LONDON, Printed by William Godbid, and are to be Sold by Moses Pitt, at the Angel over against the little North Door of St. Paul's Church. 1674.   

OBSERVATIONS OF THE GROWTH OF METALS.  
IT is altogether unnecessary to my present purpose, to examine, whether Metals and Minerals, as if they were a kind of subterraneal Plants, do properly grow as Vegetables do. For this Inquiry belongs to another place, but not to this, where the reference made in the 39th page of the foregoing Paper does not oblige me to speak of the Growth of Metals in any other than a lax and popular sense, in which a Metal may be said to grow, if a portion of Matter being assigned, wherein as yet Men can find either no Metal, as Gold or Tin, or but such a quantity of it; this being exposed to the Air, will after a time either afford some Metal where there appeared none before, or a greater proportion of Metal than it had before.  
Observations of this kind requiring length of time, as well as residence near places abounding with Minerals, I have little or no opportunity to make any of them myself, at least with the wariness, that to me seems due to Observations that I think not easy to be well made. And therefore I must content myself to set down what I have been able to learn by conversing with Mineralists and Travellers, and to add some particulars that I met with in Authors of good Credit.  

OBSERVATIONS ABOUT THE Growth of TIN.  
AN ancient Owner of Mines, being asked by me, Whether he could, otherwise than upon the Conjectures of vulgar Tradition, prove, that Minerals grow even after the Veins have been dug? Answered affirmatively; and being desired to let me know his proofs, he gave me these that follow.  
He told me, that not far from his House there was a Tin-Mine, which the old Diggers affirmed to have been left off, some said eighty, some an hundred & twenty years ago, because they had by their washing and vanning separated all the Ore from the rest of the Earth, and yet of late years they found it so richly impregnated with Metalline Particles, that it was wrought over again with very good profit, and preferred to some other Mines that were actually wrought, and had never been so robbed. And when I objected, that probably this might proceed from the laziness and unskilfulness of Workmen in those times, who left in the Earth the Tin that was lately separated, and might then have been so; I was answered, that 'twas a known thing in the Country, that in those times the Mine-men were more careful and laborious to separate the Metalline part from the rest of the Ore, than now they are.  
He also affirmed to me, that in his own time some Tenants and Neighbours of his (employed by him) having got all the Ore they could out of a great quantity of stuff, dug out of a Tin-Mine, they laid the remains in great heaps exposed to the Air, and within twenty and thirty years after, found them so richly impregnated, that they wrought them over again with good benefit.  
And lastly he assured me, that, in a Work of his own, wherein he had exercised his skill and experience, (which is said to be very great) to separate all the particles of the Tin from the Terrestrial substances, that were dug up with it out of the Vein, he caused Dams to be made to stop the Earthy Substance, which the Stream washed away from the Ore, giving passage to the water after it had let fall this Substance, which lying in heaps exposed to the Air, within ten or twelve years, and sometimes much less, he examined this or that heap, and found it to contain such store of Metalline particles, as invited him to work it again and do it with profit. And yet this Gentleman was so dexterous at separating the Metalline from the other parts of Tinore, that I could (not without wonder) see what small Corpuscles he would, to satisfy my Curiosity, sever from vast quantities (in proportion) of Earthy and other Mineral stuff.  
Relations agreeable to these, I received from another very ingenious Gentleman that was conversant with Tin-Mines, and lived not far from more than one of them.  
I was the more solicitous to procure an information about the Growth of this Metal, because the bulk of that, which is used in Europe, being found in England, I have met with little or no mention of the Growth of it in Outlandish Writers.   

OBSERVATIONS ABOUT THE Growth of LEAD.  
AS for the Growth of Lead in the Ore exposed to the Air, I remember, I enquired about it of a Person of Quality, who had a Patent for divers Leaden Mines that were supposed to contain Silver, and wrought some of them himself at no small charge, yet not without profit; and, as I remember, he answered me, that the Lead-Ore, that had been wrought and laid in heaps, did, in tract of time, grow impregnated with Metal again, and, as experience manifested, became worth working a second time. And indeed some Mineralists deliver it as a general Observation, that the Growth and Renascence of Metals is more manifest in Lead than in any other of them. Fessularum mons in Hetruria, says Boccatius Certardus, who delivers it as a most approved Truth, Florentiae Civitati imminens, lapiaes plumbarios habet, qui si excidantur brevi temporis spatio novis Incrementis instaurantur. J. Gerhard. in Decade quaestionum, pag. m. 22.  
Tu subtilius ne quaeras (says Agricola, speaking of the Growth of Mines in general) sed tantummodo refer animum ad cuniculos, & considera, eos adeò interdum memoriâ hominum in angustum venisse, ut aliqua sui parte nullum aut admodum difficilem praebeant transitum, cum eos satis latè agere soleant Fossores, ne transituros impediant. In tales autem angustias sunt adducti propter accretionem materiae ex qua lapis est factus.  
But whether this increment of Lead is observable in all Mines of that Metal, I was induced to doubt by the answer given me by a Gentleman, whose House was seated near several Lead-Mines, and who was himself Owner of one or two, which he yet causes to be wrought: For this Gentleman, though a Chemist, assured me, that in the Country where he lives, which is divided by the Sea from that of the Person abovementioned, he never observed the Lead-Ore to increase, either out of the Veins or in them; but that in some places, whence Ore had been dug thirty or forty, if not fifty, years before, he perceived not on the sides of the passages, whence the Ore had been dug, that any other had grown in its place, or that the passages, though narrow before, were sensibly straightened, much less blocked up.  
And indeed, if there were no other Arguments in the case, the straightening of the ancient passages in process of time would not convince me. For, when I con●ider, that the Soils that abound with Metals do usually also abound with waters, which are commonly imbibed by the neighbouring Earth; and when I consider too, that water is somewhat expanded by being turned into Ice, and that this expansion is made, (as I have often tried) though slowly, yet with an exceeding great force, by which it often stretches or breaks the Vessels that contain it: When I consider these things, I say, I am apt to suspect, that sometimes the increasing narrowness of the subterraneal passages in Mines may proceed from this, that the Soil that environs them, if they lie not deep, may have the water, imbibed by them, frozen in sharp Winters. By which glaciation, the moistened portion of the Soil must forcibly endeavour to expand itself, and actually do so in the parts contiguous to the passage, since there it finds no resistance: And though the expansion made in one year or two be but small, and therefore not observed; yet, in a succession of many Winters, it may by degrees grow to be very considerable. But this suspicion I suggest not, that I would deny the Growth of Minerals, but to recommend this Argument for it to further Consideration. And yet I take this to be a better proof, than what is much relied on by some Writers of Metals, who urge, that in Churches, and other magnificent Buildings, that are Leaded over, the Metalline Roofs, in a long tract of years, grow far more ponderous, in so much that often times there is a necessity to remove them, and exchange them for Brass ones. For though this plausible Argument be urged by several Writers, and among them by the Learned Io. Gerhardus, pag. m. 22; yet I fear they proceed upon a Mistake. For having had some occasion to observe and inquire after this kind of Lead, I soon suspected, that the increment of weight, (which sometimes may indeed be very great) was no clear proof of the real Growth of the Metal itself. For in that which I had occasion to consider, the additional weight as well as bulk seemed to proceed from Acetous or other Saline Corpuscles of the Timber of those Buildings, which by degrees exhaling and corroding that side of the Lead which they fastened on, turned i● with themselves into a kind of Ceruse: Which suspicion I shall briefly make probable by noting, 1. That I have found by trial purposely made, that Woods afford an acid, though not merely acid, liquor, capable of corroding Lead. 2. That 'tis known, that Led turned into Ceruse increases notably in weight, some say, (for I had not opportunity to try it) above six or seven in the hundred. 3. That from the Sheets of Lead that have very long covered Churches and the like Buildings, there is often obtained by scraping a good proportion of white Lead, which I have known much preferred by an eminent Artist to common Ceruse, when a white Pigment was to be employed. And, by the way, men's finding this Ceruse not on that side of the Lead that is exposed to the outward Air, (where I scarce ever observed any) but on the inside that regards the Timber and other woods work, may disabuse those that fancied this Ceruse to be a part of the Led calcined by the Beams of the Sun, that strike immediately upon the Metal. And if to this it be added, that by Distillation and otherwise I have found cause to suspect, that Alabaster and White Marble may emit Spirituous parts that will invade Lead; it may be doubted, whether what Galen relates of the great Intumescence of Leaden bands or fastenings, wherewith the Feet of Statues were fastened (to their Pedestals,) be a sure Argument of the real Growth of that Metal in the Air.  
But I begin to digress, and seemingly to the prejudice of the particular Scope of this Paper; but yet not to that of one of the main Scopes of all my Physical Writings, the Disquisition and Advancement of Truth.   

OBSERVATIONS ABOUT THE Growth of IRON.  
I Did not find in one of our chief Mines of Iron, that there was any notice taken of the Growth of that Metal; but in another place or two, some that deal in Iron-Ore, informed me, that they believe it grows, and may be regenerated; and upon that account one of them set up a Work, contiguous to some Land of mine, to melt over again the remainder of Ore that had been already wrought (at a great distance from that place) and had for some Ages lain in heaps exposed to the free Air; but with what success this chargeable Attempt has been made, I am not yet informed.  
But of the Growth of Iron in the Island of Ilva or Elva, in the Tyrrhene Sea, not far from the Coast of Tuscany, not only ancient Authors, as Pliny and Strabo, take special notice, but modern Mineralists of very good credit, as Falopius and Caesalpinus, particularly attest the same thing; of whom the latter speaks thus: 
Lib. III. Cap. 6.  Vena ferri copiosissima est in Italia; ob eam nobilitata, Ilva; Tyrreni Maris Insula, incredibili copiâ etiam nostris temporibus eam gignens: Nam terra; quae eruitur dum vena effoditur, tota procedente temporè in venam convertitur.  
And the experienced Agricola gives us the like account of a place in his Country, Germany, 
Agric. de Vet. & Nou. Met. Lib. II. Cap. 15.  In Lygiis, says he, ad Sagam oppidum in pratis eruitur ferrum, fossis ad altitudinem bipedaneam acts. Id decennio renatum denuò foditur, non aliter ac Ilvaeferrum.  
The Learned johan. Gerhardus, out of a Book which he calls Conciones Metallica; I suppose he means the High-Dutch Sermons of Mathesius, (whose Language I understand not) has this notable passage to our present purpose: 
J. Gerhard. Professor Tubingensis, Decad. Quaest Physico chymicarum, pag. m. 18.  Relatum mihi est a metallico fossore, ad Ferrarias, quae non longè Ambergâ distant, terram inanem cum ferri Minera erutam, quam vocant den Gummer, mixtam cum recrementis ferri, quae appellater der Sinder, congestam in cumulos, instar magni cujusdam valli, solibus pluviisque exponi, & decimo quinto anno denuò excoqui, eliquarique ferrum tantae tenacitatis, ut sola laminae inde procudantur.   

OBSERVATIONS ABOUT THE Growth of SILVER.  
OF the Growth, as is supposed, of Silver in the form of Trees or Grass or other Vegetables, I have met with some Instances among Mineralists, and I have elsewhere mentioned, that an Acquaintance of mine showed me a Stone, wherein he affirmed the Silver, I saw in it, to have increased since he had it. But for certain Reasons, none of these Relations seem to me very proper to my present purpose; in order to which I shall therefore set down only one Instance, which I lately met with in a French Collection of Voyages, published by a Person of great Curiosity and Industry, (from whose Civility I received the Book.) For there, in an account given by a Gentleman of his Country of a late Voyage he made to Peru, wherein he visited the famous Silver-Mines of Potosi, I found a passage which speaks to this sense: Le meilleur Argent, etc. i.e. 
Voyage du Sicur au Peru, pag. 15.  The best Silver in all the Indies and the purest is that of the Mines of Potosi; the chief have been found in the Mountain of Aranzasse: And, (some Lines being interposed) 'tis added, that they draw this Metal even from the Mineral Earth's that were in times past thrown aside, when the ground was open, and the Groves and Shafts that are in the Mountains were made; it having been observed that in these recrements Metal had been form afresh since those times, which sufficiently shows the propensity of the Soil to the production of this Metal; yet 'tis true, that these impregnated Earth's yield not so much as the ordinary Ore which is found in Veins betwixt the Rocks.   

OBSERVATIONS ABOUT THE Growth of GOLD.  
AS for the Growth of Gold, the Inquiries I have yet made among Travellers give me no great satisfaction about it, and though I have spoken with several that have been at the Coast of Guiny, and in Congo, and other Parts of Afric, where much Gold is to be had; yet I could not learn by them, that they, or any Acquaintance of theirs among the Natives, had seen any Mines or Veins of Gold, (which yet divers Authors affirm to be found in more than one Kingdom in Ethiopia, and in some other African Countries.) And having afterwards met with a Learned Traveller, that had carefully visited the famous Gold-Mine of Cremnitz in Hungary, he answered me, That he did not learn from the Miners, whether or no the Oars of Gold etc. did really grow or were regenerated in tract of time, by being exposed to the Air, or upon any other account; but the Grand Over●eer, who was Lord of part of the Soil, told him, that he thought the whole Mountain to abound with particles of Gold, and therefore was wont, when the Diggers had almost exhausted the Vein, to cast in store of Earth, and dig up other neighbouring places, which, being kept there as in a Conservatory, would afterwards afford Gold, as the Mine did before.  
And, if a late Germane Professor of Physic do not misinform us, his Country affords us an eminent Instance of the Growth or Regeneration of Gold. Nam Corbachi, 
Johan. Gerhardus in Decade Quastion●●● pag. ●● 19  says he, quae est Civitas westpha●iae sub ditione Comitis de Isenborg & Waldeck, Au●um excoquitur ex cumulis congestis, ita ut ●●ngulis quadrienni●s iterum elaboretur cumulus unus, semper se restaurante nature, etc.    

POSTSCRIPT.  
SInce the setting down of the foregoing Observations, I casually met with a curious Book of Travels, lately made by the very Ingenious Dr. Edward Brown, and finding in pag. 100 a couple of Relations, that seem pertinently referable, the one, to a passage abovecited out of Agricola, in the Notes about the Growth of Lead, and the other to the present Title about the) Growth of Gold; I thought fit to annex them in the Learned Authors own words, viz.  
1. Some passages in this Mine cut through the Rock, and long ●isus'd, have grown up again: And I observed the sides of some, which had been formerly wide enough, to carry their Ore through, to approach each other, so as we passed with difficulty. This happens most in moist places; the passages unite n●t from the top to the bottom, but from one side to another.  
2. The common yellow Earth of the Country near Cremnitz, especially of the Hills towards the West, although not esteemed o'er, affords some Gold: And in one place, I saw a great part of an Hill digged away, which hath been cast into the Works, washed and wrought in the same manner as pounded Ore, with considerable profit.  
THe foregoing Observations about the Growth of Gold and other Metals are not all that I might, perhaps without being blamed for it, have referred to that Title. But all my Papers, wherein other Observations of this kind were set down, are not now at hand, and divers other Instances, that I have met with among Writers of the Growth of Metals, (taking that expression in the sense I formerly declared) do not seem to me so pertinent in this place, because the improving Oars were not exposed, nor perchance accessible, to the Air. And even as to the Instances that I have now mentioned, till severer Observations have been made, to determine whether it be partly the contact or the operation of the Air, or some internal disposition, analogous to a Metalline Seed or Ferment, that causes this Metalline Increment, I dare not be positive; though I thought the Interest of the Air in this Effect might make it pardonable, to add on this occasion to the History of Nature some particulars, of which the Cause conjecturally proposed may be probable enough to countenance a Suspicion, till further Experience have more clearly instructed us.  
To what has been said of the Growth of Metals in the Air, I might add some Instances of the Growth of Fossile Salts, and of some other Minerals: But, besides that these belong to the Paper about the Saltnesses of the Air; what has been already said may suffice for the present occasion.   

POSTSCRIPT.  
AFter what I writ in the 23th page of the foregoing Disoourse, having an opportunity to look again upon the Marchasite there mentioned to have been Hermetically sealed up after its surface had been freed from the grains of Vitriolate Salt that adhered to it, I perceived, that, notwithstanding the Glass had been so closely stopped, yet there plainly appeared from the outside of the mass some grains of an Efflorescence, whose colour, between blue and green, argued it to be of a Vitriolate nature. If this be seconded with other trials made with the like success, it may suggest new thoughts about the Growth of Metals and Minerals, especially with reference to the Air.  
FINIS.   

SOME ADDITIONAL EXPERIMENTS Relating to the SUSPICIONS ABOUT THE HIDDEN QUALITIES of the AIR.  
By the Honourable ROBERT boil, Fellow of the Royal Society.  
LONDON, Printed by William Godbid, and are to be Sold by Moses Pitt, at the Angel over against the little North Door of St. Paul's Church. 1674.   

SOME ADDITIONAL EXPERIMENTS Relating to the SUSPICIONS ABOUT THE Hidden Qualities of the AIR.  
THe ESSAY about Suspicions of some hidden Qualities of the Air, having been detained somewhat long at the Press, that it might come abroad accompanied with the other Tracts designed to attend i●, whilst I was rumaging among several Papers to look for some other things, I met now and then with an Experiment or Observation, that seemed to relate to some of the things delivered in that Tract; and though they be in themselves of no great moment, I am content to annex them to the rest, because, as in that company they may signify somewhat, so I am unwilling that any matter of fact, relating to such a Subject, should perish to save the labour of transcribing.  

EXPER. I.  
Having occasion to dulcify some Calx of Dantzig-Vitriol, from which the Oil had been a good while before distilled; water was put upon two large portions of it, that the liquor might be impregnated with the Vitriolate particles remaining in the Calx; the water put upon one of these portions was, soon after it was sufficiently impregnated, filtrated and gently abstracted, by which means it afforded many drams of a kind of Salt of Vitriol that seemed to differ very little from the Vitriol that had been calcined: But the water that was put upon the other portion of calcined Vitriol, was in a wide-mouthed vessel left in the Air for a month or six weeks; after which time, when it came to be abstracted after the manner formerly recited, it afforded many drams of a Salt that did not then, nor long after, look at all like common Vitriol, or like the other, but shot white almost like Salt-petre, or some other untincted Salt. Whether this Experiment will constantly succeed, and at other Seasons of the Year than that 'twas made in, which was Summer, I had not the opportunity to make a full trial, though I endeavoured it. But that the Air may have a great stroke in varying the Salts obtainable from calcined Vitriol, seemed the more probable, because we had some Colcothar that had lain many months, if not some years, in the Air, but in a place sheltered from the Rain; and having caused a lixivium to be made of it, to try what sort or plenty of Saline particles it would yield, we found, when the superfluous moisture was exhaled, that they began to shoot into Salt far more white than Vitriol, and very differing from it in its figure and way of Concretion.   

EXPER. II.  
We took Colcothar of Venereal Vitriol carefully dulcified, and leaving it in my Study in the Month of january and February, 
This was made at Oxford.  by weighing it carefully before an ounce of it was exposed to the Air, and after it had continued there some weeks, we found it to have increased in weight four grains and about a quarter, besides some little dust that stuck to the Glass.  
This sight Experiment is here mentioned, that, being compared with the next ensuing Trial, it may appear, that the difference of Airs, Seasons, Calces of Vitriol, or other Circumstances, may produce a notable disparity in the Increment of weight, the exposed Bodies gain in the Air.   

EXPER. III.  
We put eight ounces of Outlandish Vitriol, calcined to a deep redness, into a somewhat broad and flat Metalline vessel, and set it by upon a shelf, in a Study that was seldom frequented; and at the same time, that we might observe what increment would be gained by exposing to the Air a larger superficies of the powder in reference to the bulk, we put into another Metalline vessel, smaller than the other, only two ounces of Colcothar, and set it on the same shelf with the other, this was done at the Vernal Equinox, (the Twelfth of March;) on the twenty fifth of june we weighed these powders again, and found the eight ounces to have gained one dram and seventeen grains; but the two ounces had acquired the same weight within a grain: Then putting them back into their former vessels, we left them in the same place as formerly, till the twenty fourth of August; when we found cause to suppose, that the greater parcel of Colcothar had met with some mischance, either by Mice or otherwise; but the lesser parcel weighed Twenty six grains heavier than it did in june, amounting now to two ounces, one dram, forty two grains, having increased, in less than six months, above an hundred grains, and consequently above a tenth part of its first weight.  
No Trial was made to discover what this acquired Substance may be, that we might not disturb the intended prosecution of the Experiment.   

EXPER. IU.  
Because in most of the Experiments of Substances exposed to be impregnated by the Air, or detain its Saline or other exotic particles, we employed Bodies prepared and much altered by the previous operation of the Fire; we thought fit to make some Trials with Bodies unchanged by the Fire, and to this purpose we took a Marchasite, which was partly of a shining and partly of a darkish colour, and which seemed well disposed to afford Vitriol; of this we took several smaller Lumps, that amounted to two ounces; these were kept in a room, where they were freely accessible to the Air, which, by reason that the House, that was seated in the Country, stood high, was esteemed to be very pure. After the Marchasites had been kept in this room somewhat less than seven weeks, we weighed them again in the same Balance, and found the two ounces to have gained above twelve grains in weight.   

EXPER. V.  
The Experiment used at the latter end of our Paper, about Celestial and Aerial Magnets, seeming to some Vixtuess very strange, and the way that I employed in making that Liquor, that turns green in the Air, being somewhat troublesome, I remember I thought fit to try upon the same ground a way of producing the same Phaenomenon more easy and more expeditious. And though perhaps this way will not succeed so constantly, nor always so well as the other, yet for its easiness and cheapness it will not probably be unwelcome to those that are desirous to see the odd Phaenomenon.  
We took then, more than once, filings of clean crude Copper, and having put on them a convenient quantity of good Spirit of Salt, we suffered the Menstruum in Heat (which need not be very great) to work upon the Metal, which it usually does slowly, and not like Aquafortis: When the Liquor had by this operation acquired a thick and muddy colour, we decanted it into a clean Glass with a wide mouth, which being left for a competent time in the open Air, the exposed Liquor came to be of a fair green, though it did not appear that any thing was precipitated at the bottom, to make it clear.   

EXPER. VI  
Perhaps it may not be impertinent to add, that I once or twice observed the fumes of a sharp Liquor to work more quickly or manifestly on a certain Metal sustained in the Air, than did the Menstruum itself that emitted those fumes on those parts of the Metal that it covered: And this brings into my mind, that, ask divers Questions of a Chemist that had been in Hungary and other parts, purposely to see the Mines; he answered me, among other things, that; as to the Ladders and other wooden work employed in one or more of the deep Hungarian Mines, those that were in the upper part of the Groves any thing near the external Air, would by the fretting Exhalations be rendered unserviceable, in not many months, whereas those Ladders and pieces of Timber, etc. that were employed in the lower part of the Mine, would hold good for two or three times as long.   

EXPER. VII.  
We took about the bigness of a Nutmeg of a certain soft but consistent Body, that we had caused to be Chemically prepared, and which in the free Air would continually emit a thick smoke: This being put into a Vial, and placed in a middle sized Receiver in our Engine, continued for some time to afford manifest fumes, whilst the exhaustion was making; till at length, the Air having been more and more pumped out, the visible ascension of fumes out of the Vial quite ceased, and the matter having remained some time in this state, the smoking substance was so altered, that it would not emit fumes, not only when the Air was let into the Receiver, but not in a pretty while after the Vial was taken out of it, till it had been removed to the window, where the Wind blowing-in fresh and fresh Air, it began to smoke as formerly.  
The other Phaenomena of this Experiment belong not to this place; but there are two, which will not be impertinent here, and the latter of them may deserve a serious Reflection.  
The first of them was, that the Substance hitherto mentioned had been kept in a large Glass, whereinto it had been distilled at least five or six weeks, and yet would smoak very plentifully upon the contact of the Air, and be kept from smoking, though the Chemical Receiver were stopped but with a piece of paper.  
The second was, that, when the Vial was put unstopped in the Receiver, and the Receiver close luted on, though no exhaustion were made, yet the white fumes did very quickly cease to ascend into the Receiver, as if this Smoke participated of the nature of Flame, and presently glutted the Air, or otherwise made it unfit (and yet without diminution of its gravity) to raise the Body that should ascend.  
FINIS.    

ANIMADVERSIONS UPON MR. HOBBES' PROBLEMATA DE VACUO.  
By the Honourable ROBERT boil, Fellow of the Royal Society.  
LONDON, Printed by William Godbid, and are to be Sold by Moses Pitt, at the Angel over against the little North Door of St. Paul's Church. 1674.   

PREFACE.  
UPON the coming abroad of Mr. Hobbes' Problemata Physica, finding them in the hands of an Ingenious Person, that intended to write a Censure of them, which several Employments private and public have, it seems; hindered him to do; I began, as is usual on such occasions, to turn over the leaves of the Book, to see what particular things it treated of. This I had not long done before I found, by obvious passages in the third Chapter, or Dialogue, as well as by the Title, which was Problemata de Vacuo, that I was particularly concerned in it; upon which I desired the Possessor of the Book, who readily consented, to leave me to examine that Dialogue, on which condition I would leave him to deal with all the rest of the Book. Nor did I look upon the Reflections I meant to make as repugnant to the Resolutions I had taken against writing Books of Controversy, since the Explications, Mr. Hobbes gave of his Problems, seemed to contain but some Variations of, or an Appendix to, his Tract De Natura Aeris, which, being one of the two first pieces that were published against what I had written, was one of those that I had expressly reserved myself the liberty to answer. But the Animadversions I first made upon Mr. Hobbes' Problems De Vacuo, having been casually mislaid ere they were finished; before I had occasion to resume my task, there past time enough to let me perceive, that his Doctrine, which 'twill easily be thought that the Vacuists disapproved, was not much relished by most of the Plenists themselves, the modernest Peripatetics and the Cartesians; each of them maintaining the Fullness of the World, upon their own grounds, which are differing enough from those of our Author, the natural Indisposition I have to Polemical Discourses, easily persuaded me to let alone a Controversy, that did not appear needful: And I had still persisted in my silence, if Mr. Hobbes had not as 'twere summoned me to break it by publishing again his Explications, which in my Examen of his Dialogue De Natura Aeris I had shown to be erroneous.  
And I did not grow at all more satisfied, to find him so constant as well as stiff an Adversary to interspersed Vacuities, by comparing what he maintains in his Dialogue De Vacuo, with some things that he teaches, especially concerning God, the Cause of Motion, and the Imperviousness of Glass, in some other of his Writings that are published in the same Volume with it. For since he asserts that there is a God, and owns Him to be the Creator of the World; and since on the other side the Penetration of Dimensions is confessed to be impossible, and he denies that there is any Vacuum in the Universe; it seems difficult to conceive, how in a World that is already perfectly full of Body, a Corporeal Deity, such as he maintains in his Append. ad Leviath. cap. 3, can have that access even to the minute parts of the Mundane Matter, that seems requisite to the Attributes and Operations that belong to the Deity, in reference to the World. But I leave Divines to consider what Influence the conjunction of Mr. Hobbes' two Opinions, the Corporeity of the Deity, and the perfect Plenitude of the World, may have on Theology. And perhaps I should not in a Physical Discourse have taken any notice of the proposed Difficulty, but that, to prevent an Imputation on the Study of Nature's Works, (as if it taught us rather to degrade than admire their Author,) it seemed not amiss to hint (in transitu) that Mr. Hobbes' gross Conception of a Corporeal God, is not only unwarranted by sound Philosophy, but ill befriended even by his own.  
My Adversary having proposed his Problems by way of Dialogue between A. and B; `twill not, I presume, be wondered at, that I have given the same form to my Animadversions; which come forth no earlier, because I had divers other Treatises, that I was more concerned for, to publish before them.  
But because it will probably be demanded, why on a Tract that is but short, my Animadversions should take up so much room? It will be requisite, that I here give an account of the bulk of this Treatise.  
And first, having found that there was not any one Problem, in whose Explication, as proposed by Mr. Hobbes, I saw cause to acquiesce, I was induced for the Readers ease, and that I might be sure to do my Adversary no wrong, to transcribe his whole Dialogue, bating some few Transitions, and other Clauses not needful to be transferred hither.  
Next, I was not willing to imitate Mr. Hobbes, 

Credo, 
De Nat. Aeris, p. 13.  (says Mr. Hobbes in his Dialogus Physicus:) Nam motus hic Restitutionis, Hobbii est, & ab illo primo & solo explicatus in Lib. de Corpore, cap. 21. Art. 1. Sine qua Hypothesi, quantuscunque labour, arse, sumptus, ad rerum Naturali● invisibiles causas inveniendas adhibeatur, frustra erit. And speaking of the Gentlemen (to whom it were not here proper for me to give Epith●tes) that used to meet at Gresham-College, and are known by the Name of the Royal Society, he thus treats them and their way of Enquiring into Nature: Conveniant, studia conserant, Experimenta faciant quantum volunt, nisi & Principiis utantur meis, nihil preficient.  A. 
Fateris ergo nihil hactenus à Collegis tuis promotam esse scientium Causarum Naturalium, nisi quod Unus eorum Machinam ●nvenerit, quâ motus excitari Aeris possit talis, ut partes Sphaerae simul undiquaque tendant ad Centrum, & ut Hypotheses Hobbianae, antè quidem satis probabiles, hinc reddantur probabiliores.  B. 
Nec fateri pudet; nam est aliquid prodire tenus, si non datur ultra.  A. 
Quid tenus? quorsum autem tantus apparatus & sumptus Machinarum factu difficilium, ut eatenus tantum prodiretis quantum ante prodierat Hobbius? Cur n●n inde potius incepistis ubi ille defiit? Cur Principiis ab illo positis non estis usi? Cumque Aristoteles rectè dixit, ignorato motu ignorari Naturam, etc.  
— Ad Causas autem, propter quas proficere ne paululum quidem potu●stis, nec poteritis, accedunt etiam aliae, ut odium Hobbii, etc.   who recites in the Dialogue we are considering the same Experiments that he had already mentioned in his Tract De Natura Aeris, without adding as his own (that I remember) any new one to them. But my unwillingness to tyre the Reader with bare Repetitions of the Arguments I employed in my Examen of that Tract, invited me to endeavour to make him some amends for the exercise of his patience by inserting, as occasion was offered, five or six new Experiments, that will not perhaps be so easily made by every Reader that will be able (now that I have perspicuously proposed them) to understand them.  
And lastly, since Mr. Hobbes has not been content to magnify ●●mself and his way of treating of Physical matters, but has been pleased to speak very slightingly of Experimentarian Philosophers (as he styles them) in general, and, which is worse, to disparage the making of elaborate Experiments; I judged the thing, he seemed to aim at, so prejudicial to true and useful Philosophy, that I thought, it might do some service to the less knowing, and less wary, sort of Readers, if I tried to make his own Explications enervate his Authority, and by a somewhat particular Examen of the Solutions he has given of the Problems I am concerned in, show, that 'tis much more easy to undervalue a frequent recourse to Experiments, than truly to explicate the Phaenomena of Nature without them. And since our Author, speaking of his Problemata Physica, (which is but a small Book) scruples not to tell His Majesty, to whom he dedicates them, that he has therein comprised (to speak in his own terms) the greatest and most probable part of his Physical Meditations; and since by the alterations, he has made in what he formerly writ about the Phaenomena of my Engine, he seems to have designed to give it a more advantageous form: I conceive, that by these selected Solutions of his, one may, without doing him the least injustice, make an estimate of his way of discoursing about Natural things. And though I would not interess the credit of Experimentarian Philosophers in no considerabler a Paper than this; yet if Mr. Hobbes' Explications and mine be attentively compared, it will not, I hope, by them be found, that the way of Philosophising he employs, is much to be preferred before that which he undervalues.   

ANIMADVERSIONS UPON MR. HOBBES' Problemata de VACUO.  A. 
MAy one, without too bold an inquisitiveness, ask, what Book you are reading so attentively?  B. 
You will easily believe you may, when I shall have answered you, that 'twas Mr. Hobbes' lately published Tract of Physical Problems, which I was perusing.  A. 
What progress have you made in it?  B. 
I was finishing the third Dialogue or Chapter when you came in, and finding myself, though not named, yet particularly concerned, I was perusing it with that attention which it seems you took notice of.  A. 
Divers of your Experiments are so expressly mentioned there, that one need not be skilled in deciphering to perceive that you are interessed in that Chapter, and therefore seeing you have heedfully read it over, pray give me leave to ask your Judgement, both of Mr. Hobbes' Opinion, and his Reasonings about Vacuum.  B. 
Concerning his Opinion, I am sorry I cannot now satisfy your Curiosity, having long since taken, and ever since kept, a Resolution to decline, at least until a time that is not yet come, the declaring myself either for or against the Plenists. But as to the other part of your Question, which is about Mr. Hobbes' Arguments for the absolute Plenitude of the World, I shall not scruple readily to answer, that his Ratiocinations seem to me far short of that cogency, which the noise he would make in the world, and the way wherein he treats both ancient and modern Philosophers that descent from him, may warrant us to expect.  A. 
You will allow me the freedom to tell you, That, to convince me, that your resentment 〈◊〉 his explicating divers of the Phaenomena of your Pneumatic Engine otherwise than you have been wont to do, (and perhaps in terms that might well have been more civil,) has h 〈…〉 share in dictating this Judgement of yours; the best way will be, that entering for a while into the party of the Vacuists you answer the Arguments he alleges in this Chapter to confute them.  B. 
Having always, as you know, forborn to declare myself either way in this Controversy, I shall not tie myself strictly to the Principles and Notions of the Vacuists, nor, though but for a while, oppose myself to those of the Plenists: But so far I shall comply with your Commands, as either upon the Doctrine of the Vacuists, or upon other grounds, to consider, whether this Dialogue of Mr. Hobbes have cogently proved his, and the Schools, Assertion, Non dari Vacuum; and whether he has rightly explained some Phaenomena of Nature which he undertakes to give an account of, and especially some produced in our Engine, whereof he takes upon him to render the genuine Causes. And this last inquiry is that which I chiefly design.  A. 
By this I perceive, that if you can make our your own Explications of your Adversaries Problems de Vacuo, and show them to be preferable to his, you will think you have done your work, and that 'tis but your secondary scope to show, that in Mr. Hobbes his way of solving them, he gives the Vacuists an advantage against Him, though not against the Plenists in general.  B. 
You do not mistake my meaning, and therefore without any further Preamble, let us now proceed to the particular Phaenomena considered by Mr. Hobbes; the first of which is an Experiment proposed by me in the one and thirtieth of the Physicomechanical Experiments concerning the Adhesion of two flat and polished Marbles, which I endeavoured to solve by the pressure of the Air. And this Experiment Mr. Hobbes thinks so convincing an one to prove the Plenitude of the World, that, though he tells us he has many cogent Arguments to make it out, yet he mentions but this one, because that, he says, suffices.  A. 
The Confidence he thereby expresses of the great force of this Argument does the less move me, because, I remember, that formerly in his Elements of Philosophy he thought it sufficient to employ one Argument to evince the Plenitude of the World, and for that one he pitched upon the Vulgar Experiment of a Gardeners Watering-Pot: But, whether he were wrought upon by the Objections made to his Inference from that Phaenomenon in your Examen of his Dialogue De Natura Aeris, or by some other Considerations, I will not pretend to divine. But I plainly perceive, he now prefers the Experiment of the cohering Marbles.  B. 
Of which it will not be amiss, though the passage be somewhat long; to read you his whole Discourse out of the Book I have in my hand.  A. 
'Tis fit that you, who for my sake are content to take the pains of answering what he says, should be eased of the trouble of reading it, which I will therefore, with your leave, take upon me. His Discourse then about the Marbles is this:  A. 
Ad probandam Universi Plenitudinem, nullum nostin Argumentum cogens?  B. 
Imò multa: Unùm autem sufficit ex eo sumptum, Quod duo corpora plana, si se mutuò secundùm amborum planitiem communem tangant, non facile in instant divelli possunt; successiuè verò facillimè. Non dico, impossibile esse duo durissima Marmora ita cohaerentia divellere, sed difficile; & vim postulare tantam, quanta sufficit ad duritiem lapidis superandam. Siquidem verò majore vi ad separationem opus sit quam illae, quâ moventur separata, id signum est non dari Vacuum.  A. 
Assertiones illae demonstratione indigent. Primò autem ostend, quomodo ex duorum durissimorum corporum, conjunctorum ad superficies exquisite laeves, diremptione difficili, sequatur Plenitudo Mundi?  B. 
Si duo plana, dura, polita Corpora (ut Marmora) collocentur unum supra alterum, ita ut eorum superficies se mutuò per omnia puncta exactè, quantum fieri potest, contingant, illa sine magna difficultate ita divelli non possunt, ut eodem instante per omnia puncta dirimantur. Veruntamen Marmora eadem, si communis eorum superficies ad Horizontem erigatur, aut non valde inclinetur, alterum ab altero facillimè (ut scis) etiam solo pondere dilabentur. Nun causa hujus rei haec est, Quod labenti Marmori succedit Aer, & relictum locum semper implet?  A. 
Certissimé. Quid ergo?  B. 
Quando verò eadem uno instante divellere conaris, nun multo major vis adhibenda est; Quam ob causam?  A. 
Ego, & mecum (puto) omnes causam statuunt, Quod spatium totum inter duo illa Marmora divulsa, simul uno instante implere Aer non potest, quantacunque celeritate fiat divulsio.  B. 
An qui spatia in Aere dari vacua contendunt, in illo Aere solo dari negant qui Marmora illa conjuncta circumdat?  A. 
Minimè, sed ubique interspersa.  B. 
Dum ergo illi, qui Marmor unum ab altero revellentes Aerem comprimunt, & per consequens Vacuum exprimunt, Vacuum faciunt locum per revulsionem relictum; nulla ergo separationis erit difficultas, saltem non major quam est difficultas corpora eadem movendi in Aere postquam separata fuerint. Itaque quoniam, concesso Vacuo, difficultas Marmora illa dirimendi nulla est, sequitur per difficultatis experientiam, nullum esse Vacuum.  A. 
Recte quidem illud infers. Mundi autem Plenitudine suppos●ta, quomodo demonstrabis possibile omnino esse ut divellantur?  B. 
Cogita primo Corpus aliquod ductile, nec nimis durum, ut ceram, in duas partes distrahi, quae tamen parts ●on minus exacte in communi plano se mutuo tangunt quam laevissima Marmora. jaem quo pacto distrahatur cera, consideremus. Nun perpetuo attenuatur donec in filum evadat tenuissimum, & omni dato crasso tenuius, & sic tandem divellitur? Eodem modo etiam durissima columnae in duas partes distrahetur, si vim tantam adhibeas, quanta sufficit ad resistentiam duritiei superandam. Sicut enim in cera partes primo extimae distrahuntur, in quarum locum succedit Aer; ita etiam in Corpore quantumlibet duro Aer locum subit partium extimarum, quae primae Vulfionis viribus dirumpuntur. Vis autem quae super at resistentiam partium extimarum Duri, facilè superabit resistentiam reliquarum. Nam resistentia prima est à Toto Duro, reliquarum verò semper à Residuo.  A. 
Ita quidem videtur consideranti, quam Corpora quaedam, praesertim verò duris●ima, fragilia sint.  
Does this Ratiocination ●eem to you as cogent, as it did to the Proposer of it?  B. 
You will quickly think it does not, and perhaps you will think it should not, if you please to consider with me some of the Reflections that the Reading of it suggested to me.  
And first, without declaring for the Vacuists Opinion, I must profess myself unsatisfied with Mr. Hobbes' way of arguing against them: For, where he says, Dum ergo illi qui Marmor unum ab altero revellentes Aerem comprimunt & per consequens Vacuum exprimunt, Vacuum faciunt locum per revulsionem relictum; nulla ergo separationis erit difficultas, saltem non major quam est difficultas corpora eadem movendi in Aere postquam separata fuerint. Itaque quoniam, concesso Vacuo, difficultas Marmora illa dirimendi nulla est, sequitur per difficultatis experientiam, nullum esse Vacuum. Methinks he expresses himself but obscurely, and leaves his Readers to guess, what the word Dum refers to. But that which seems to be his drift in this passage, is, that, since the Vacuists allow interspersed Vacuities, not only in the Air that surrounds the conjoined Marbles, but in the rest of the ambient Air, there is no reason, why there should be any difficulty in separating the Marbles, or at least any greater difficulty than in moving the Marbles in that Air after their separation. But, not to consider, whether his Adversaries will not accuse his phrase of squeezing out a Vacuum as if it were a Body, they will easily answer, that notwithstanding the Vacuities they admit in the ambient Air, a manifest reason may be given in their Hypothesis of our finding a difficulty in the Divulsion of the Marbles. For, the Vacuities they admit being but interspersed, and very small, and the Corpuscles of the Atmosphere being according to them endowed with Gravity, there leans so many upon the upper surface of the uppermost Marble, that that stone cannot be at once perpendicularly drawn up from the lower Marble contiguous to it, without a force capable to surmount the weight of the Aerial Corpuscles that lean upon it. And this weigh● has already so constipated the neigh●bouring parts of the ambient Air that he, that would perpendicularly raise the upper Marble from the lower shall need a considerable force to mak● the Revulsion, and compel the al● ready contiguous parts of the incum●bent Air to a subingression into the pores or intervals intercepted be●tween them. For the Conatus of him that endeavours to remove the uppe● Marble, whilst the lower surface o● it is fenced from the pressure of th● Atmosphere by the Contact of th● lower Marble which suffers no Air to come in between them, is not assisted by the weight or pressure of the At●mosphere, which, when the Marble● are once separated, pressing as strongly against the undermost surface o● the upper Marble, as the incumbent Atmospherical Pillar does against th● upper surface of the same Marble● the hand that endeavours to raise i● in the free Air has no other resistance than that small one of the Marble own weight to surmount.  A. 
But what say you to the Reason that Mr. Hobbes, and, as he thinks, all others give of the difficulty of the often mentioned Divulsion, namely, Quod spatium totum inter duo illa Marmora divulsa simul uno instante implere Aer non potest, quantacunque celeritate fiat divulsio.  B. 
I say, that, for aught I know, the Plenists may give a more plausible account of this Experiment, than Mr. Hobbes has here done; and therefore abstracting from the two opposite Hypotheses, I shall further say, That the genuine Cause of the Phaenomenon seems to be that which I have already assigned; and that difficulty of raising the upper stone that accompanies the Airs not being able to come in all at once, to possess the space left between the surfaces of the two Marbles upon their separation, proceeds from hence, that, till that space be filled with the Atmospherical Air, the hand of him that would lift up the superior Marble cannot be fully assisted by the pressure of the Air against the lower surface of that Marble.  A. 
This is a Paradox, and therefore I shall desire to know on what you ground it?  B. 
Though I mention it but as a Conjecture proposed ex abundanti, yet I shall on this occasion countenance it with two things; the first, that, since I declare not for the Hypothesis of the Plenists as 'tis maintained by Mr. Hobbes, I am not bound to allow, what the common Explication, adopted by my Adversary, supposes; namely, that either Nature abhors a Vacuum (as the Schools would have it,) or that there could be no Divulsion of the Marbles, unless at the same time the Air were admitted into the room that Divulsion makes for i●. And a Vacuist may tell you, that, provided the strength employed to draw up the superior Marble be great enough to surmount the weight of the Aerial Corpuscles accumulated upon it, the divulsion would ensue, though by Divine Omnipotence no Air or other Body should be permitted to fill the room made for it by the divulsion; and that the Air's rushing into that space does not necessarily accompany, but in order of Nature and time follow upon, a separation of the Marbles, the Air that surrounded their contiguous surfaces being by the weight of the collaterally superior Air impelled into the room newly made by the divulsion. But I shall rather countenance what you call my Paradox by an Experiment I purposely made in our Pneumatical Receiver, where having accommodated two flat and polished Marbles, so that the lower being fixed, the upper might be laid upon it and drawn up again as there should be occasion, I found, that if, when the Receiver was well exhausted, the upper Marble was by a certain contrivance laid flat upon the lower, they would not then cohere as formerly, but be with great ease separated, though it did not by any Phaenomenon appear, that any Air could come to rush in, to possess the place given it by the recess of the upper Marble, whose very easy avulsion is as ●asily explicable by our Hyphothesis, since the pressure of that little Air, that remained in the Receiver, being too faint to make any at all considerable resistance to the avulsion of the upper Marble, the hand that drew it up had very little more than the single weight of the stone to surmount.  A. 
An Anti-plenist had expected, that you would have observed, that the difficult separation of the Marbles in the open Air does rather prove, that there may be a Vacuum, than that there can be none. For in case the Air can succeed as fast at the sides as the divulsion is made, a Vacuist may demand, whence comes the difficulty of the separation? And if the Air cannot fill the whole room made for it by the separated Marbles at the fame instant they are forced asunder, how is a Vacuum avoided for that time, how small soever, that is necessary for the Air to pass from the edges to the middle of the room newly made?  B. 
What the Plenists will say to your Argument I leave them to considered but I presume, they will be able to give a more plausible account of the Phaenomenon we are treating of, than is given by Mr. Hobbes.  A. 
What induces you to dislike his Explication of it?  B. 
Two things, the one, that I think the Cause he assigns improbable; and the other, that I think another, that is better, has been assigned already.  
And first, whereas Mr. Hobbes requires to the Divulsion of the Marbles a force great enough to surmount the hardness of the stone, this is asserted gratis, which it should not be; since it seems very unlikely, that the weight of so few pounds as will suffice to separate two coherent Marbles of about an Inch, for instance, in Diameter, should be able to surmount the hardness of such solid stones as we usually employ in this Experiment. And though it be generally judged more easy to bend, if it may be, or break a broader piece of Marble caeteris paribus, than a much narrower; yet, whereas neither I, nor any else that I know, nor I believe Mr. Hobbes, ever observed any difference in the resistance of Marbles to separation from the greater or lesser thickness of the stones; I find by constant experience, that, caeteris paribus, the broadness of the coherent Marbles does exceedingly increase the difficulty of disjoining them: Insomuch that, whereas not many pounds, as I was saying, would separate Marbles of an Inch, or a lesser, Diameter; when I increased their Diameter to about four Inches, if I misremember not, there were several Men that successively tried to pull them asunder without being able by their utmost force to effect it.  A. 
But what say you to the Illustration, that Mr. Hobbes, upon the supposition of the World's Plenitude, gives of our Phaenomenon by drawing asunder the opposite pa●●s of a piece of Wax?  B. 
To me it seems an Instance improper enough. For first, the parts that are to be divided in the Wax are of a soft and yielding consistence, and according to him of a ductile, or, if you please, of a tractile nature, and not, as the parts of the coherent Marbles, very solid and hard. Next, the parts of the Wax do not stick together barely by a superficial contact of two smooth Planes, as do the Marbles we are speaking of; but have their parts implicated, and as it were entangled with one another. And therefore they are far from a disposition to slide off, like the Marbles; from one another, in how commodious a posture soever you place them. Besides 'tis manifest, that the Air has opportunity to succeed in the places successively deserted by the receding parts of the attenuated Wax; but 'tis neither manifest, nor as yet well proved by Mr. Hobbes, that the Air does after the same manner succeed between the two Marbles, which, as I lately noted, are not forced asunder after such a way, but are, as himself speaks, severed in all their points at the same instant.  A. 
I know, you forget not what he says of the dividing of a hard Column into two parts by a force sufficient to overcome the resistance of its hardness.  B. 
He does not here either affirm, that he, or any he can trust, has seen the thing done; nor does he give us any such account of the way wherein the Pillar is to be broken; whether in an erected, inclined, or horizontal posture; nor describe the particular circumstances that were fit to be mentioned in order to the solution of the Phaenomenon. Wherefore, till I be better informed of the matter of fact, I can scarce look upon what Mr. Hobbes says of the Pillar, as other than his Conjecture, which now I shall the rather pass by, not only because the case is differing from that of our polished Marbles, which are actually distinct Bodies, and only contiguous in one Commissure; but also, because I would hasten to the second reason of my dislike of Mr. Hobbes' Explication of our Phaenomenon, which is, that a better has been given already, from the pressure of the Atmosphere upon all the superficial parts of the upper Marble save those that touch the Plane of the lower.  A. 
You would have put fair for convincing Mr. Hobbes himself, at least would have put him to unusual shifts, if you had succeeded in the attempt you made, among other of your Physicomechanical Experiments, to disjoin two coherent Marbles, by suspending them horizontally in your Pneumatical Receiver, and pumping out the Air that environed them; for, from your failing in that attempt, though you rendered a not improbable Reason of it, Mr. Hobbes took occasion, in his Dialogue De Nat●●a Aeris, to speak in so high a strain as this: Nihil isthic erat quod ageret pondus; Experimento hoc excogitari contra opinionem eorum qui Vacuum asserunt aliud argumentum fortius aut evidentius non potuit. Nam si duorum cohaerentium alterutrum secundùm eam viam, in quae jacent ipsae contiguae superficies, propulsum ●sset, facile separarentur, Aere praximo in locum relictum successiuè semper influente; sed illa ita divellere, ut simul totum amitterent contactum, impossibile est, mundo pleno. Oporteret enim aut motum fieri ab uno termino ad alium in instant, aut duo corporae eodem tempore in eodem esse loco: Quorum utrumvis dicere, est absurdum.  B. 
You may remember, that where I relate that Experiment, I expressed a hope, that, when I should be better accommodated than I then was, I might attempt the Trial with prosperous success, and accordingly afterwards, having got a lesser Engine than that I used before, wherewith the Air might be better pumped out and longer kept out, I cheerfully repeated the Trial. To show then, that when two coherent Marbles are sustained horizontally in the Air, the Cause, why they are not to be forced asunder, if they have two or three Inches in Diameter, without the help of a considerable weight, is the pressure I was lately mentioning of the ambient Air; I caused two such coherent Marbles to be suspended in a large Receiver, with a weight at the lowermost, that might help to keep them steady; but was very inconsiderable to that which their Cohesion might have surmounted; then causing the Air to be pumped by degrees out of the Receiver, for a good while the Marbles stuck close together, because during that time the Air could not be so far pumped out, but that there remained enough to sustain the small weight that endeavoured their divulsion: But when the Air was further pumped out, at length the Spring of the little, but not a little expanded, Air, that remained, being grown too weak to sustain the lower Marble and its small clog, they did, as I expected, drop off.  A. 
This will not agree over-well with the confident and triumphant expressions just now recited.  B. 
I never envied Mr. Hobbes' forwardness to triumph, and am content, his Conjectures be recommended by the confidence that accompanies them, if mine be by the success that follows them. But to confirm the Explication given by me of our Phaenomenon, I shall add, that as the last mentioned Trial, which I had several times occasion to repeat, shows, that the cohesion of our two contiguous Marbles would cease upon the withdrawing of the pressure of the Atmosphere; so by another Experiment I made, it appears, that the supervening of that pressure sufficed to cause that Cohesion. For, in prosecution of one of the lately mentioned Trials, having found, that when the Receiver was well exhausted, two Marbles, though considerably broad, being laid upon one another after the requisite manner, their adhesion was, if any at all, so weak, that the uppermost would be easily drawn up from off the other; we laid them again one upon the other, and then letting the external Air flow into the Receiver, we found, according to expectation, that the Marbles now cohered well, and we could not raise the uppermost but accompanied with the lowermost. But I am sensible, I have detained you too long upon the single Experiment of the Marbles: And though I hope the stress Mr. Hobbes lays on it will plead my excuse, yet to make your Patience some amends, I shall be the more brief in the other particulars that remain to be considered in his Dialogue De Vacuo. And 'twill not be difficult for me to keep my promise without injuring my Cause, since almost all these particulars being but the same which he has already alleged in his Dialogue De Nature Aeris, and I soon after answered in my Examen of that Dialogue, I shall need but to refer you to the passages where you may find these Allegations examined, only subjoyning here some Reflections upon those few and slight things, that he has added in his Problems De Vacuo.  A. 
I may then, I suppose, read to you the next passage to that long one, you have hitherto been considering, and it is this: Ad Vacuum nunc revertor: Quas causas sine suppositione Vacui redditurus es illorum effectuum, qui ostenduntur per Machinam illam quae est in Collegio Greshamensi?  B. 
Machina illa—  B. 
Stop here, I beseech you, a little, that, before we go any further, I may take notice to you of a couple of things that will concern our subsequent Discourse.  
Whereof the first is, that it appears by Mr. Hobbes' Dialogue about the Air, that the Explications he there gave of some of the Phaenomena of the Machina Boyliana, were directed partly against the Virtuosos, that have since been honoured with the Title of the Royal Society, and partly against the Author of that Engine, as if the main thing therein designed were to prove a Vacuum. And since he now repeats the same explications, I think it necessary to say again, that if he either takes the Society or me for professed Vacuists, he mistakes, and shoots beside the mark; for, neither they nor I have ever yet declared either for or against a Vacuum.  
And the other thing I would observe to you, is, that Mr. Hobbes seems not to have rightly understood, or at least not to have sufficiently heeded in what chiefly consists the advantage, which the Vacuists may make of our Engine against him: For, whereas in divers places he is very solicitous to prove, that the cavity of our Pneumatical Receiver is not altogether empty, the Vacuists may tell him, that since he asserts the absolute plenitude of the World, he must, as indeed he does, reject not only great Vacuities, but also those very small and interspersed ones, that they suppose to be intercepted between the solid corpuscles of other bodies, particularly of the Air: So that it would not confute them to prove, that in our Receiver, when most diligently exhausted, there is not one great and absolute Vacuity, or, as they speak, a Vacuum coacervatum, since smaller and disseminated Vacuities would serve their turn. And therefore they may think their Pretensions highly favoured, as by several particular effects, so by this general Phaenomenon of our Engine, that it appears by several Circumstances, that the Common or Atmospherical Air, which, before the pump is set a work, possessed the whole cavity of our Receiver, far the greatest part is by the intervention of the pump made to pass out of the cavity into the open Air, without being able, at least for a little while, to get in again; and yet it does not appear by any thing alleged by Mr. Hobbes, that any other body succeeds to fill adequately the places deserted by such a multitude of Aerial corpuscles.  A. 
If I guess aright, by those words, (viz. it appears not by any thing alleged by Mr. Hobbes,) you design to intimate, that you would not in general prejudice the Plenists.  B. 
Your conjecture was well founded: For I think divers of them, and particularly the Cartesians, who suppose a subtle Matter or AEther fine enough to permeate glass, though our common Air cannot do it, have not near so difficult a task to avoid the Arguments the Vacuifts may draw from our Engine, as Mr. Hobbes, who, without having recourse to the porosity of glass, which indeed is impervious to common Air, strives to solve the Phaenomena, and prove our Receiver to be always perfectly full, and therefore as full at any one time as at any other of common or Atmospherical Air, as far as we can judge of his opinion by the tendency or import of his Explications.  A. 
Yet, if I were rightly informed of an Experiment of yours, Mr. Hobbes may be thereby reduced either to pass over to the Va●uist's, or to acknowledge some AEtherial or other matter more subtle than Air, and capable of passing through the pores of glass; and therefore, to show yourself impartial between the Vacuists and their Adversaries in this Controversy, I hope you will not refuse to gratify the Plenists by giving your friends a more particular account of the Experiment.  B. 
I know which you mean, and remember it very well. For, though I long since devised it, yet having but the other day had occasion to peruse the Relation I writ down of one of the best Trials, I think I can repeat it, almost in the very words, which, if I mistake not, were these:  
There was taken a Bubble of thin white glass, about the bigness of a Nutmeg, with a very slender stem, of about four or five Inches long, and of the bigness of a Crows-quill. The end of the Quill being held in the flame of a Lamp blown with a pair of Bellows, was readily and well sealed up, and presently the globous part of the glass, being held by the stem, was kept turning in the flame, till it was red hot and ready to melt; then being a little removed from the flame, as the included Air began to lose of its agitation and spring, the external Air manifestly and considerably pressed in one of the sides of the Bubble. But the glass being again, before the cold could crack it, held as before in the flame, the rarified Air distended and plumped up the Bubble; which being the second time removed from the flame, was the second time compressed; and, being the third time brought back to the flame, swelled as before, and removed, was again compressed, (either this time or the last by two distinct cavities;) till at length, having satisfied ourselves, that the included Air was capable of being condensed or dilated without the ingress or egress of Air (properly so called) we held the Bubble so long in the flame, strengthened by nimble blasts, that not only it had its sides plumped up, but a hole violently broken in it by the over-rarified Air, which, together with the former watchfulness, we employed from time to time to discern if it were any where cracked or perforated, satisfied us that it was till then entire.  A. 
I confess, I did not readily conceive before, how you could, (as I was told you had,) make a solid Vessel, wherein there was no danger of the Airs getting in or out, whose cavity should be still possessed with the same Air, and yet the Vessel be made by turns bigger and lesser. And, though I presently thought upon a well stopped bladder, yet I well foresaw, that a distrustful Adversary might make some Objections, which are by your way of proceeding obviated, and the Experiment agrees with your Doctrine in showing, how impervious we may well think your thick Pneumatick Receivers are to common Air, since a thin glass Bubble, when its pores were opened or relaxed by flame, would not give passage to the Springy particles of the Air, though violently agitated; for if those particles could have got out of the pores, they never would have broke the Bubble, as at length a more violent degree of Heat made them do; nor probably would the Compression, that afterwards ensued of the Bubble by the ambient Air, be checked near so soon, if those Springy Corpuscles had not remained within to make the resistance. Methinks, one may hence draw a new proof of what I remember you elsewhere teach, that the Spring of the Air may be much strengthened by Heat. For, in our case, the Spring of the Air was thereby enabled to expand the compressed glass, it was imprisoned in, in spite of the resisting pressure of the external Air; and yet, that this pressure was considerable, appears by this, that the weight of so small a Column of Atmospherical Air, as could bear upon the Bubble, was able to press in the heated glass, in spite of the resistance of its tenacity and arched figure.  B. 
Yet that which I mainly designed in this Experiment was, (if I were able) to show and prove at once, by an Instance not liable to the ordinary exceptions, the true Nature of Rarefaction and Condensation, at least of the Air. For, to say nothing of the Peripatetic Rarefaction and Condensation, strictly so called, which I scruple not to declare, I think to be physically inconceptible or impossible; 'tis plain by our Experiment, that, when the Bubble, after the Glass had been first thrust in towards the Centre, was expanded again by heat, the included Air possessed more room than before, and yet it could perfectly fill no more room than formerly, each Aerial Particle taking up, both before and after the heating of the Bubble, a portion of space adequate to its own bulk; so that in the Cavity of the expanded Bubble we must admit either Vacuities interspersed between the Corpuscles of the Air, or that some fine Particles of the Flame, or other subtle matter, came in to fill up those Intervals, which matter must have entered the Cavity of the Glass at its pores: And afterwards, when the red-hot Bubble was removed from the flame, it is evident, that, since the grosser particles of the Air could not get through the Glass, which they were not able to do, even when vehemently agitated by an ambient Flame, the Compression of the Bubble, and the Condensation of the Air, which was necessarily consequent upon it, could not, supposing the Plenitude of the World, be performed without squeezing out some of the subtle matter contained in the cavity of the Bubble, whence it could not issue but at the pores of the Glass. But I will no longer detain you from Mr. Hobbes his Explications of the Machina Boyliana; to the first of which you may now, if you please, advance.  A. 
The passage I was going to read, when you interrupted me, was this:  B. 
Machina illa eosdem effectus producit, quos produceret in loco non magno magnus inclusus ventus.  A. 
Quomodo ingreditur istuc ventus? Machinam nosti Cylindrion esse cavum, aeneum, in quem protruditur Cylindrus alius solidus ligneus, coriotectus, (quem suctorem dicunt) ita exquisitè congruens, ut ne minimus quidem Aer inter corium & aes intrare (ut putant) possit.  B. 
Scio, & quò Suctor facilius intrudi possit, foramen quoddam est in superiori parte Cylindri, per quod Aer (qui suctoris ingressum alioqui impedire possit) emittatur. Quod foramen aperire possunt & claudere quoties usus postulat. Est etiam in Cylindri cavi recessu summo datus aditus Aeri in globum concavum Vitreum, quem etiam aditum claviculâ obturare & aperire possunt quoties volunt. Denique in globo vitreo summo relinquitur foramen satis amplum, (claviculâ item claudendum & recludendum) ut in illum quae volunt immittere possint, experiendi causâ.  B. 
The imaginary wind to which Mr. Hobbes here ascribes the effects of our Engine, he formerly had recourse to in the 13th page of his Dialogue, and I have sufficiently answered that passage of it in the 45th and 46th pages of my Examen, to which I therefore refer you.  A. 
I presume, you did not overlook the comparison Mr. Hobbes annexes to what I last read out of his Problems, since he liked the conceit so well, that we meet with it in this place again, though he had formerly printed it in his Dialogue De Natura Aeris. The words (as you see) are these: Tota denique Machina non multum differt, si naturam ejus spectes, à Sclopeto ex Sambuco, quo pueri se delectant, imitantes Sclopetos militum, nisi quòd major sit, & majori arte fabricatus, & pluris constet.  B. 
I could scarce, for the reason you give, avoid taking notice of it. And if Mr. Hobbes intended it for a piece of Ralliery, I willingly let it pass, and could easily forgive him a more considerable attempt than this, to be revenged on an Engine that has destroyed several of his opinions: But, if he seriously meant to make a Physical Comparison, I think he made a very improper one. For, not to urge, that one may well doubt how he knows, that in the enclosed cavity of his Potgun, there is a very vehement wind, (since that does not necessarily follow from the compreffion of the included Air:) In Mr. Hobbes' Instrument, the Air, being forcibly compressed, has an endeavour to expand itself, and when it is able to surmount the resistance of its prison, that part that is first disjoined is forcibly thrown outwards; whereas in our Engine it appears by the passage lately cited of our Examen, that the Air is not compressed but expanded in our Receiver, and if an intercourse be opened, or the Vessel be not strong enough, the outward Air violently rushes in: And if the Receiver chance to break, the fragments of the glass are not thrown outwards, but forced inwards.  A. 
So that, whether or no Mr. Hobbes could have pitched upon a Comparison more suitable to his Intentions, he might easily have employed one more suitable to the Phaenomena.  B. 
I presume, you will judge it the less agreeable to the Phaenomena, if I here subjoin an Experiment, that possibly you will not dislike; which I devised to show, not only that in our exhausted Receivers there is no such strong endeavour outwards, as most of Mr. Hobbes' Explications of the things that happen in them are built upon, but that the weight of the Atmospherical Air, when 'tis not resisted by the counterpressure of any internal Air, is able to perform what a weight of many pounds would not suffice to do.  A. 
I shall the more willingly learn an Experiment to this purpose, because in your Receivers, the rigidity of the glass keeps us from seeing, by any manifest change of its figure, whether, if it could yield without breaking, it would be pressed in, as your Hypothesis requires.  B. 
The desires to obviate that very difficulty, for their satisfaction, that had not yet penetrated the grounds of our Hypothesis, made me think of employing, instead of a Receiver of Glass, one of a stiff and tough, but yet somewhat flexible, Metal. And accordingly having provided a new Pewter Porringer, and whelmed it upside down upon an Iron plate fastened to (the upper end of) our Pneumatical Pump, we carefully fastened by Cement the orifice to the plate, and though the inverted Vessel, by reason of its stiffness and thickness and the convexity of its superficies, were strong enough to have supported a great weight without changing its figure; yet, as soon as by an exsuction or two the remaining part of the included Air was brought to such a degree of expansion, that its weakened Spring was able to afford but little assistance to the tenacity and firmness of the Metal, the weight of the pillar of the incumbent Atmosphere (which by reason of the breadth of the Vessel was considerably wide also) did presently and notably depress the upper part of the Porringer, both lessening its capacity and changing its figure; so that instead of the Convex surface, the Receiver had before, it came to a Concave one, which new figure was somewhat, though not much, increased by the further withdrawing of the included and already rarified Air. The Experiment succeeded also with an other common Porringer of the same Metal. But in such kind of Vessels, made purposely of Iron plates, it will sometimes succeed and sometimes not, according to the Diameter of the vessel and the thickness of the plate, which was sometimes strong enough and sometimes too weak to resist the pressure of the incumbent Air. And sometimes I found also, that the vessel would be thrust in, not at the top but side-ways, in case that side were the only part that were made too thin to resist the pressure of the Ambient; which Phaenomenon I therefore take notice of, that you may see, that that powerful pressure may be exercised laterally as well as perpendicularly.  
Perhaps this Experiment, and that I lately recited of an Hermetically sealed Bubble, by their fitness to disprove Mr. Hobbes' Doctrine, may do somewhat towards the letting him see, that he might have spared that not over-modest and wary expression, where speaking of the Gentlemen that meet at Gresham-College, (of whom I pretend not to be one of the chief) he is pleased to say, Experimenta faciant quantum volunt, nisi Principiis utantur meis nihil proficient. But let us, if you please, pass on to what he further alleges to prove, that the space in the exhausted Receiver, which the Vacuists suppose to be partly empty, is full of Air. (Video (says A.) si suctor trudatur usque ad fundum Cylindri AEnei, obturenturque for amina, Secuturum esse, dum suctor retrahitur, locum in Cylindro cavo relictum fore vacuum. Nam ut in locum ejus succedat Aer, est impossible. To which B. answers, Credo equidem, suctorem cum Cylindri cavi superficie satis arctè cohaerere ad excludendum stramen & plumam, non autem Aerem neque Aquam. Cogita enim, quod non ita accuratè congruerent, quin undiquaque interstitium relinqueretur, quantum tenuissimi capilli capax esset. Retracto ergo suctore, tantum impelleretur Aeris, quantum viribus illis conveniret quibus Aer propter suctoris Retractionem reprimitur, idque sine omni difficultate sensibili. Quanto autem interstitium illud minus esset, tantum ingrederetur Aer velocius: Vel si contactus sit, sed non per omnia puncta, etiam tunc intrabit Aer, modò suctor ma●ore vi retrahatur. Postremò, etsi con●actus ubique exactissimus sit, vi tamen ●atis auct● per cochleam ferream, tum ●orium cedet, tum ipsum es; atque ita quoque ingredietur Aer. Credin' tu, ●osfibile esse duas superficies it a exactè ●omponere, ut has compositas esse suppo●unt illi; aut corium ita durum esse, ut Aeri, qui Cochleae ope incutitur, nihi omnino cedat? Corium quanquam optimum admittit aquam, ut ipse scis, fortè fecisti unquam iter vento & pluvi● 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉. Itaque dubitare no● potes, quin retractus Suctor tantum A● ris in Cylindrum adeoque in ipsum Rec●piens incutiat, quantum sufficit ad locu● semper relictum perfectè implendu● Effectus ergo, qui oritur à Retractio● suctoris, alius non est quam ventu● ventus (inquam) vehementissimus● q● ingreditur undiquaque inter Suctoris s●● perficiem convexan, & Cylindri aen● concavam, proceditque (versâ clavicul●● in cavitatem globl Vitrei, sive (u●●●ocatur Recipientis.  
The Substance of this Ratiocin●●tion having been already proposed ●● Mr. Hobbes in his Dialogue of th● Air, the 11th page, I long since answered it in the 30th and some of th● following pages of my Examen; an● therefore I shall only now take noti●● in transitu of some slight whether a●●ditions or variations, that occur ●● what you have been reading. And first, I see no probability in what he gratis asserts, that so thick a Cylinder of Brass, as made the chief part of the pump of our Engine, should yield to the Sucker, that was moved up and down in it, though by the help of an Iron rack; and whereas he adds, that the leather, that surrounds the more solid part of the Sucker, would yield to such a force; it seems, that that compression of the leather should by thrusting the solid parts into the pores make the leather rather less than more fit to give passage to the Air; nor would it however follow, notwithstanding Mr. Hobbes' Example, that, because a Body admits Water, it must be pervious to Air: For I have several times, by ways elsewhere taught, made Water penetrate the pores of Bladders, and yet Bladders resist the passage of the Air so well, that even when Air included in them was sufficiently rarified by Heat, or by our Engine, it was necessary for the Air to break them before it could get out; which would not have been, if it could have escaped through their pores. What Mr. Hobbes inculcates here again concerning his ventus vehementissimus, you will find answered in the place of my Examen I lately directed you to.  A. 
We may then proceed to Mr. Hobbes' next Explication, which he proposes in these terms:  A. 
Causam video nunc unius ex Machinae mirabilibus, nimirum cur Suctor, postquam est aliquatenus retractus & deinde amissus, subitò recurrit ad Cylindri summitatem. Nam Aer, qui vi magna fuit impulsus, rursus per repercussionem ad externa vi eadem revertitur.  B. 
Atque hoc quidem Argumenti satis est etiam solum, quòd locus à suctore relictus non est Vacuus. Quid enim aut attrahere aut impellere suctorem potuit ad locum illum unde retractus erat, si Cylindrus fuisset vacuus? Nam ut Aeris pondus aliquod id efficere potuisset, falsum esse satis supra demonstravi ab eo quod Aer in Aere gravitare non potest. Nosti etiam, quod cum è recipiente Aerem omnem (ut illi loquuntur) exegerint, possunt tamen trans vitrum id quod intus fit videre, & sonum, si quis ●iat, inde audire. Id quod solum, etsi nullum aliud Argumentum esset (sunt autem multa,) ad probandum, nullum esse in Recipiente Vacuum, abundè sufficit.  B. 
Here are several things joined together, which the Author had before separately alleged in his often-mentioned Dialogue. The first is, the Cause he assigns of the ascension of the Sucker forcibly depressed to the bottom of the exhausted Cylinder, and then let alone by him that pumped; to which might be added; that this ascension succeeded, when the Sucker was clogged with an hundred pound weight. This Explication of Mr. Hobbes you will find examined in the 33th and 39th, and some ensuing pages of my Discourse. And as to his denying, that the weight or pressure of the Air could drive up the Sucker in that Phaenomenon, because the Air does not weigh in Air, we may see the contrary largely proved in divers places of my Examen, and more particularly and expressly in the four first pages of the third Chapter. And whereas he says in the last place, that the visibility of Bodies included in our Receivers, and the propagation of Sound, (which, by the way, is not to be understood of all Sound that may be heard, though made in the exhausted Receiver,) are alone sufficient Arguments to prove no Vacuum: I have considered that passage in the answer I made to the like allegation in the 45th page of the Examen; and shall only observe here, that, since the Vacuists can prove, that much of the Air is pumped out of the exhausted Receiver, and will pretend, that, notwithstanding many interspersed Vacuities, there may be in the Receiver corporeal substance enough to transmit Light and stronger Sounds, Mr. Hobbes has not performed what he pretended, if he have but barely proved, that there may be Substances capable of conveying Light and Sound in the cavity of our Receiver, since he triumphantly asserts, Nullum esse in Recipienti Vacuum. But we may leave Mr. Hobbes and his Adversaries to dispute out this point, and go on to the next passage.  A. 
Which follows in these words: Ad illud autem, quod si Vesica aliquatenus inflata in Recipiente includatur, paulo post per exuctionem aeris inflatur vehementius & dirumpitur, quid respondes?  B. 
Motus partium Aeris undiquaque concurrentium velocissimus & per concursum in spatiis brevissimis numeroque infinitis gyrationis velocissimae vesicam in locis innumerabilibus simul & vi magna, instar totidem terebrarum, penetrate, praesertim si vesica, antequam immittatur, quò magis resistat aliquatenus inflata fit. Postquam autem Aer penetrans semel ingressus est, facile cogitare potes, quo pacto deinceps vesicam tendet, & tandem rumpet. Verùm si antequam rumpatur, versâ claviculâ, Aer externus admittatur, videbis vesicam propter vehementiam motus temperatam diminutâ tensione rugosiorem. Nam id quoque observatum est. jam si haec, quam dixi, causa minùs tibi vide atur verisimilis, vide an tu aut alius quicunque imaginari potest, quo pacto vesica distendi & rumpi possit à viribus Vacui, id est, Nihili.  B. 
This Explication Mr. Hobbes gave us in the 19th page of his Dialogue De Natura Aeris, and you may find it at large confuted in the latter part of the third Chapter of my Examen. Nor does, what he here says in the close about the Vires Vacui or Nihili, deserve to detain us, since there is no reason at all, that the Vacuists should ascribe to nothing a power of breaking a Bladder, of whose rupture the Spring of the included Air supplies them so easily with a sufficient Cause.  
After what Mr. Hobbes has said of the breaking of a Bladder, he proceeds to an Experiment which he judges of affinity with it, and his Academian having proposed this Question: Unde fit ut animalia tam cito, nimirum spatio quatuor minutorum horae, in recipiente interficiantur?  
For answer to it our Author says:  B. 
Nun animalia sic inclusa insugunt in Pulmones Aerem vehementissimè motum? Quo motu necesse est ut transitus sanguinis ab uno ad alterum cordis ventriculum interceptus, non multò pòst sistatur. Cessatio autem sanguinis, Mors est. Possunt tamen animalia cessante sanguine reviviscere, si Aer externus satis maturè intromittatur, vel ipsa in Aerem temperatum, antequam refrixerit sanguis, extrahantur.  
This Explication is not probable enough, to oblige me to add any thing about it to what I have said in the 49th and the two following pages of my Examen; especially the most vehement motion, ascribed to the Air in the Receiver, having been before proved to be an Imaginary thing. You may therefore, if you please, take notice of the next Explication.  
[Idem Aer (says he) in Recipiente Carbones ardentes extinguit, sed & illi, si, dum satis calidi sunt, eximantur, relucebunt. Notissimum est, quòd in fodinis Carbonum terreorum (cujus rei experimentum ipse vidi) saepissime è lateribus foveae ventus quidam undiquaque exit, qui fossores interficit ignemque extinguit, qui tamen reviviscunt si satis cito ad Aerem liberum extrahantur.]  
This Comparison which Mr. Hobbes here summarily makes, he more fully displayed in his Dialogue De Natura Aeris, and I considered, what he there alleged, in the 52th page and the two next of my Examen. And, though I will not contradict Mr. Hobbes in what he historically asserts in this passage; yet I cannot but somewhat doubt, whether he mingles not his conjecture with the bare matter of fact. For, though I have with some curiosity visited Mines in more places than one, and proposed Questions to Men that have been conversant in other Mines, both elsewhere and in England (and particularly in Derbysbire where Mr. Hobbes lived long;) yet I could never find, that any such odd and vehement wind, as Mr. Hobbes ascribes the Phaenomenon to, had been by them observed to kill the Diggers, and extinguish well-lighted Coals themselves: And indeed, it seems more likely, that the damp, by its tenacity or some peculiarly malign quality, did the mischief, than a wind, of which I found not any notice taken; especially since we see, what vehement winds Men will be able to endure for a long time, without being near-killed by them; and that it seems very odd, that a wind, that Mr. Hobbes does not observe to have blown away the Coals, that were let down, should be able (instead of kindling them more fiercely) to blow them out.  A. 
The last Experiment of your Engine, that your Adversary mentions in these Problems, is delivered in this passage:  A. 
Si phialam aqua in Recipiens dimiseris, exucto Aere bullire videbis aquam. Quid ad hoc Respondebis?  B. 
Credo sanè in tanta Aeris motitatione saltaturam esse aquam, sed ut calefiat nondum audivi. Sed imaginabile non est, Saltationem illam à Vacuo nasci posse.  B. 
This Phaenomenon he likewise took notice of, and attempted to explicate in his abovementioned Dialogue, which gave me occasion in the 46th and 47th pages of my Examen, to show how unlikely 'tis, that the vehement motion of the Air should be the cause of it; but he here tells us, that 'tis not imaginable, that this dancing of the water (as he is pleased to call it) proceeds from a vacuum, nor do I know any Man that ever pretended, that a vacuum was the efficient cause of it. But the Vacuists perhaps will tell him, that, though the bubbling of the water be not an effect of a vacuum, it may be a proof of it against him; for they will tell him, that it has been formerly proved, that a great part of the Atmospherical Air is by pumping removed out of our exhausted Receiver, and consequently can no more, as formerly, press upon the surface of the water. Nor does Mr. Hobbes show what succeeds in the room of it; and therefore it will be allowable, for them to conclude against him (though not perhaps against the Cartesians) that there are a great many interspersed Vacuities left in the Receiver, which are the occasion, though not the proper efficient cause, of the Phaenomenon. For they will say, that the Springy Particles of the yet included Air, having room to unbend themselves in the spaces deserted by the Air that was pumped out, the Aerial and Springy Corpuscles, that lay concealed in the pores of the water, being now freed from the wont pressure that kept them coiled up in the liquor, expanded themselves into numerous bubbles, which, because of their comparative lightness, are extruded by the water, and many of them appear to have risen from the bottom of it. And Mr. Hobbes' vehement wind, to produce the several Circumstances of this Experiment, must be a lasting one. For, after the agitation of the Pump has been quite left off, provided the external Air be kept from getting in, the bubbles will sometimes continue to rise for an hour after. And that which agrees very well with our Explication and very ill with that of Mr Hobbes's, is, that, when by having continued to pump a competent time, the water has been freed from the Aerial particles that lurked in it before, though one continue to pump as lustily as he did, yet the water will not at all be covered with bubbles as it was, the Air that produced them being spent; though, according to Mr. Hobbes' Explication, the wind in the Receiver continuing, the dance of the water should continue too.  A. 
I easily guess, by what you have said already, what you may say of that Epiphonema wherewith Mr. Hobbes (in his 18th page) concludes the Explications of the Phaenomena of your Engine. [Spero jam te certum esse, says he, nullum esse Machinae illius Phaenomenon, quo demonstrari potest ullum in Universo locum dari corpore omni vacuum.]  B. 
If you guessed aright, you guessed that I would say, that as to the Phaenomena of my Engine, my business was to prove, that he had not substituted good Explications of them in the place of mine, which he was pleased to reject. And as for the proving a Vacuum by the Phaenomena of my Engine, though I declared that was not the thing intended, yet I shall not wonder, that the Vacuists should think those Phaenomena give them an advantage against Mr. Hobbes. For, though in the passage recited by you he speak more cautiously than he is wont to do, yet, by what you may have already observed in his Argumentations, the way he takes to solve the Phaenomena of our Engine, is by contending, that our Receiver, when we say it is almost exhausted, is as full as ever (for he will have it perfectly full,) of common Air; which is a conceit so contrary to I know not how many Phaenomena, that I do not remember I have met with or heard of any Naturalist, whether Vacuist or Plenist, that having read my Physicomechanical Experiments and his Dialogue, has embraced his opinion.  A. 
After what you have said, I will not trouble you with what he subjoins about Vacuum in general, where having made his Academian say, [Mundum scis finitum esse, & per Consequens vacuum esse oportere totum illud Spatium quod est extra mundum infinitum. Quid impedit quo minus vacuum illud cum Aere mundano permisceatur?] He answers: De rebus transmundanis nihil scio. For I know, that it concerns not you to take notice of it. But possibly the Vacuists will think, he fathers upon them an Impropriety they would not be guilty of, making them speak, as if they thought, the ultra-mundan Vacuum were a real Substance that might be brought into this World and mingled with our Air. And since, for aught I know, Mr. Hobbes might have spared this passage, if he had not designed it should introduce the slighting answer he makes to it; I shall add, that by the account Mr. Hobbes has given of several Phaenomena within the World, 'tis possible, that the Vacuists may believe his Profession of knowing nothing of things beyond it.  
After the Experimenta Boyliana (as your other Adversary calls them;) Mr. Hobbes proceeds to the Torricellian Experiment, of which he thus discourses:  A. 
Quid de experimento senses Torricelliano, probante Vacuum per Argentum vivum hoc modo: est in seq. figura ad A, pelvis sive aliud vas, & in eo Argentum vivum usque ad B; est autem C D tubus vitreus concavus repletus quoque Argento vivo. Hunc tubum si digito obturaveris erexerisque in vase A, manumque abstuleris, descendet Argentum vivum à C; verùm non effundetur totum in pelvim, sed sistetur in distantia quadam, puta in D. Nun ergo necessarium est, ut pars tubi inter C & D sit vacua? Non enim puto negabis quin superficies tubi concava & Argenti vivi convexa se mutuo exquisitissim● contingant.  B. 
Ego neque nego contactum, nequ● vim Consequentiae intelligo.  
By which passage it seems that he still persists in the solution of this Experiment, which he gave in his Dialogue De Natura Aeris, and formerly did, for the main, either propose, or adopt, in his Elements of Philosophy.  B. 
This opinion or explication o● Mr. Hobbes I have, as far as concerns me, considered in the 36th, and some ensuing pages, of my Examen, to which it may well suffice me to refer you. But yet let me take notice of what he now alleges:  B. 
Si quis (says he) in Argentum vivum, quod in vase est, vesicam immerserit inflatam, nun illa amot â man● emerget?  A. 
Ita certè, etsi esset vesica ferre● vel ex materia quacunque praeter Aurum.  B. 
Vides igitur ab Aere penetran● posse Argentum vivum.  A. 
Etiam, & quidem illâ ipsâ vi quam à pondere accipit Argenti vivi.  
I confess this Allegation did a little surprise me: It concerned Mr. Hobbes to prove, that as much Air, as was displaced by the descending Mercury, did at the orifice of the Tube, immersed in stagnant Mercury, invisibly ascend to the upper part of the pipe. To prove this he tells us, that a bladder full of Air being depressed in Quicksilver, will, when the hand that depressed it is removed, be squeezed up by the very weight of the Mercury, whence it follows, that Air may penetrate Quicksilver. But I know not, who ever denied, that Air environed with Quicksilver may thereby be squeezed upwards; but, since even very small bubbles of Air may be seen to move in their passage through Mercury, I see not, how this Example will at all help the Proposer of it. For 'tis by mere accident, that the Air included in the bladder comes to be buoyed up, because the bladder itself is so; and if it were filled with Water instead of Air, or with Stone instead of Water, it would nevertheless emerge, as himself confesses it would do, if it were made of Iron, or of any Matter besides Gold, because all other Bodies are lighter in specie than Quicksilver. But since the emersion of the bladder is manifest enough to the sight, I see not how it will serve Mr. Hobbes' turn, who is to prove that the Air gets into the Torricellian Tube invisibly; since 'tis plain, that even heedful observation can make our Eyes discover no such trajection of the Air; which (to add that enforcement of our Argument) must not only pass unseen through the sustained Quicksilver, but must likewise unperceivedly dive, in spite of its comparative lightness, beneath the surface of the ponderous stagnant Mercury, to get in at the orifice of the erected Tube. But let us, if you please, hear the rest of his Discourse about this Experiment.  A. 
Though it be somewhat prolix, yet, according to my custom hitherto, I will give it you verbatim.  B. 
Simul atque Argentum vivum descenderit ad D, altius erit in vase A quam antè, nimirum plus erit Argenti vivi in vase quam erat ante descensum, tanto quantum capit pars tubi C, D. Tanto quoque minus erit Aeris extra tubum quam ante erat. Ille autem Aer qui ab Argento vivo loco suo extrusus est, (suppositâ universi plenitudine) quò abire potest nisi ad eum locum, qui in tubo inter C & D à descensu Argenti vivi relinquebatur? sed quâ, inquies, viâ in illum locum successurus est? Quà, nisi per ipsum corpus Argenti vivi Aerem urgentis? Sicut enim omne grave liquidum, sae ipsius pondere, Aerem, quem descendendo premit, ascendere cogit (si via alia non detur) per suum ipsius corpus; ita quoque Aerem quem premit ascendendo, (si viae alia non detur) per suum ipsius corpus transire cogit. Manifestum igitur est, suppositâ mundi plenitudine posse Aerem externum ab ipsa gravitate Argenti vive cogi in locum illum inter C & D. Itaque Phaenomenon illud necessitatem vacui non demonstrat. Quoniam autem corpus Argenti vivi penetrationi, quae fit ab Aere, non nihil resistit, & ascensioni Argenti vivi in vase A resistit Aer; quando illae duae resistentiae aequales erunt, tunc in tubo sistetur alicubi Argentum vivum; atque ibi est D.  B. 
In answer to this Explication I have in my Examen proposed divers things, which you may there meet with: And indeed his Explication has appeared so improbable to those that have written of this Experiment, that I have not found it embraced by any of them, though, when divers of them opposed it, the Phaenomena of our Engine were not yet divulged. Not then needlessly to repeat what has been said already, I shall on this occasion only add one Experiment, that I afterwards made, and it was this: Having made the Torricellian Experiment (in a strait Tube) after the ordinary way, we took a little piece of a fine Bladder, and raising the Pipe a little in the stagnant Mercury, but not so high as the surface of it, the piece of Bladder was dexterously conveyed in the Quicksilver, so as to be applied by one's finger to the immersed orifice of the Pipe, without letting the Air get into the Cavity of it; then the Bladder was tied very strait and carefully to the lower end of the Pipe, whose orifice (as we said) it covered before, and then the Pipe being slowly lifted out of the stagnant Mercury, the impendent Quicksilver appeared to lean but very lightly upon the Bladder, being so near an exact AEquilibrium with the Atmosperical Air, that, if the Tube were but a very little inclined, whereby the gravitation of the Quicksilver, being not so perpendicular, came to be somewhat lessened, the Bladder would immediately be driven into the orifice of the Tube, and to the Eye, placed without, appear to have acquired a concave superficies instead of the convex it had before. And when the Tube was reerected, the Bladder would no longer appear sucked in, but be again somewhat protuberant. And if, when the Mercury in the Pipe was made to descend a little below its station into the stagnant Mercury, if, I say, at that nick of time the piece of Bladder were nimbly and dexterously applied, as before, to the immersed orifice, and fastened to the sides of the Pipe, upon the lifting the Instrument out of the stagnant Mercury, the Cylinder of that Liquor being now somewhat short of its due height, was no longer able fully to counterpoise the weight of the Atmospherical Air, which consequently, though the Glass were held in an erected posture, would press up the Bladder into the orifice of the Pipe, and both make and maintain there a Cavity sensible both to the Touch and the Eye.  A. 
What did you mainly drive at in this Experiment?  B. 
To satisfy some Ingenious Men, that were more diffident of, than skilful in, hydrostatics, that the pressure of the external Air is capable of sustaining a Cylinder of 29 or 30 Inches of Mercury, and upon a small lessening of the gravitation of that ponderous liquor, to press it up higher into the Tube. But a farther use may be made of it against Mr. Hobbes' pretention. For, when the Tube is again erected, the Mercury will subside as low as at first, and leave as great a space as formerly was left deserted at the top; into which how the Air should get to fill it, will not appear easy to them, that, like you and me, know by many trials, that a Bladder will rather be burst by Air than grant it passage. And if it should be pretended, either that some Air from without had yet got through the Bladder, or that the Air, that they may presume to have been just before included between the Bladder and the Mercury, made its way from the lower part of the Instrument to the upper; 'tis obvious to answer, That 'tis no way likely, that it should pass all along the Cylinder unseen by us; since, when there are really any Aerial Bubbles, though smaller than Pins heads, they are easily discernible. And in our case, there is no such resistance of the Air to the ascension of the stagnant Mercury, as Mr. Hobbes pretends in the Torricellian Experiment made the usual way.  A. 
But, whatever becomes of Mr. Hobbes' Explication of the Phaenomenon; yet may not one still say, that it affords no advantage to the Vacuists against him?  B. 
Whether or no it do against other Plenists, I shall not now consider; but I doubt, the Vacuists will tell Mr. Hobbes, that he is fain in two places of the Explication, we have read, to suppose the Plenitude of the World, that is, to beg the thing in question, which 'tis not to be presumed they will allow.  A. 
But may not Mr. Hobbes say, that 'tis as lawful for him to suppose a Plenum, as for them to suppose a Vacuum.  B. 
I think he may justly say so; but 'tis like they will reply, that, in their way of explicating the Torricellian Experiment, they do not suppose a Vacuum as to Air, but prove it. For they show a great space, that having been just before filled with Quicksilver, is now deserted by it, though it appeared not, that any Air succeeded in its room; but rather, that the upper end of the Tube is either totally or near totally so devoid of Air, that the Quicksilver may without resistance, by barely inclining the Tube, be made to fill it to the very top: Whereas Mr. Hobbes is fain to have recourse to that which he knows they deny, the Plenitude of the World, not proving by any sensible Phaenomena, that there did get in through the Quicksilver Air enough to fill the deserted part of the Tube, but only concluding, that so much Air must have got in there, because, the World being full, it could find no room any where else; which the Vacuists will take for no proof at all, and the Cartesians, though Plenists, who admit an Etherial matter capable of passing through the pores of Glass, will, I doubt, look upon but as an improper Explication.  A. 
I remember on this occasion another Experiment of yours, that seems unfavourable enough to Mr. Hobbes' Explication, and you will perhaps call it to mind when I tell you, that 'twas made in a bended Pipe almost filled with Quicksilver.  B. 
To see whether we understand one another, I will briefly describe the Instrument I think you mean. We took a Cylindrical Pipe of Glass, closed at the upper end, and of that length, that being dexterously bend at some Inches from the bottom, the shorter leg was made as parallel as we could to the longer: In this Glass we found an expedient, (for 'tis not easy to do,) to make the Torricellian Experiment, the Quicksilver in the shorter leg serving instead of the stagnant Quicksilver in the usual Baroscope, and the Quicksilver in the longer leg reaching above that in the shorter about eight or nine and twenty Inches. Then, by another artifice, the shorter leg, into which the Mercury did not rise within an Inch of the top, was so ordered, that it could in a trice be Hermetically sealed, without disordering the Quicksilver. And this is the Instrument that I guess you mean.  A. 
It is so, and I remember, that it is the same with that, which in the Paradox about Suction you call, whilst the shorter leg remains unsealed, a Travelling Baroscope. But when I saw you make the Experiment, that leg was Hermetically sealed, an Inch of Air in its natural or usual consistence being left in the upper part of it, to which Air you outwardly applied a pair of heated Tongues.  B. 
Yet that, which I chiefly aimed at in the Trial, was not the Phaenomenon I perceive you mean; for, my design was, by breaking the Ice for them, to encourage some, that may have more skill and accommodation than I then had, to make an attempt that I did not find to have been made by any; namely, to reduce the Expansive force of Heat in every way included Air, if not in some other Bodies also, to some kind of measure, and, if 'twere possible, to determine it by weight. And I presumed, that at least the event of my Trial would much confirm several Explications of mine, by showing, that Heat is able, as long as it lasts, very considerably to increase the Spring or pressing power of the Air. And in this conjecture I was not mistaken; for, having shut up, after the manner newly recited, a determinate quantity of uncomprest Air, which, (in the Experiment you saw,) was about one Inch; we warily held a pair of heated Tongues near the outside of the Glass, (without making it touch the Instrument, for fear of breaking it,) whereby the Air being agitated was enabled to expand itself to double its former Dimensions, and consequently had its Spring so strengthened by Heat, that it was able to raise all the Quicksilver in the longer leg, and keep up or sustain a Mercurial Cylinder of about nine and twenty Inches high, when by its expansion it would, if it had not been for the Heat, have lost half the force of its elasticity. But whatever I design in this Experiment, pray tell me, what use you would make of it against Mr. Hobbes.  A. 
I believe, he will find it very difficult to show, what keeps the Mercury suspended in the longer leg of the Travelling Baroscope, when the shorter leg is unstopped, at which it may run out; since this Instrument may, as I have tried, be carried to distant places, where it cannot with probability be pretended, that any Air has been displaced by the fall of the Quicksilver in the longer leg, which perhaps fell long before above a mile off. And when the shorter leg is sealed, it will be very hard for Mr. Hobbes to show there the odd motions of the Air, to which he ascribes the Torricellian Experiment. For, if you warily incline the Instrument, the Quicksilver will rise to the top of the longer leg, and immediately subside, when the Instrument is again erected, and yet no Air appears to pass through the Quicksilver interposed between the ends of the longer and the shorter leg. But that which I would chiefly take notice of in the Experiment, is, that upon the external application of a hot Body to the shorter leg of the Baroscope, when 'twas sealed up, the included Air was expanded from one Inch to two, and so raised the whole Cylinder of Mercury in the longer leg, and, whilst the heat continued undiminished, kept it from subsiding again. For, if the Air were able to get unseen through the body of the Quicksilver, why had it not been much more able, when rarified by Heat, to pass through the Quicksilver, than for want of doing so to raise and sustain so weighty a Cylinder of Mercury? I shall not stay to inquire on this occasion, how Mr. Hobbes will, according to his Hypothesis, explicate the rarefaction of the Air to double its former dimensions, and the condensation of it again; especially since, asserting that part of the upper leg, that is unfilled with the Quicksilver, to be perfectly full of Air, he affirms that, which I doubt he cannot prove, and which may very probably be disproved by the Experiment you mention in the Discourse about Suction, where you show, to another purpose, that in a Travelling Baroscope, whose shorter leg is sealed, if the end of the longer leg be opened, whereby it comes indeed to be filled with Air, the pressure of that Air will enable the subjacent Mercury notably to compress the Air included in the shorter leg.  B. 
I leave Mr. Hobbes to consider what you have objected against his Explication of the Torricellian Experiment; to which I shall add nothing, though perhaps I could add much, because I think it may be well spared, and our Conference has lasted long already.  A. 
I will then proceed to the la●● Experiment recited by Mr. Hobbes in his Problemata de Vacuo.  A. 
Si Phialam, collum habent●● longiusculum, ea●démque omni Corpor● praeter Aerem vacuam ore sugas, continuoque Phialae os aquae immergas, videbis aquam aliquousque ascendere in Phialam. Quî fieri hoc potest nisi factum sit Vacuum ab exuctione Aeris, in euj●● locum possit Aqua illa ascendere?  B. 
Concesso Vacuo, oportet quaeda● l●cae vacua fuisse in illo Aere, etiam qu● erat intra Phialam ante suctionem. C●● ergo non ascendebat Aqua ad ea imple●da absque suctione? Is qui sagit Phi●lam, neque in ventrem quicquam, neq●● in pulmones, neque in os è Phialu ex●git. Quid ergo agit? Aerum comm●vet, & in partibus ejus conatum sugen●● efficit per os exeundi, & non admittendo, conaetum redeundi. Ab his conatibus contrariis compo●●tur circumitio in●●● Phialam, & conatus exeundi quaquaversum. Itaque Phialae ore aquae immerso, Aer in subjectam aquam penetrate è Phiala egrediens, & tuntundem aquae in Phialam cogit.  
Praeterea vis illa magna suctionis facit, ut sugentis labra c●m collo Phialae aliquando arctissimè cohaereant propter contactum exqusitissimum.  B. 
As to the first Clause of Mr. Hobbes' account of our Phaenomenon, the Vacuists will easily answer his Question by acknowledging, that there were indeed interspersed Vacuities in the Air contained in the Vial before the suction; but they will add, there was no reason, why the Water should ascend to fill them, because, being a heavy body, it cannot rise of itself, but must be raised by some prevalent weight or pressure, which then was wanting. Besides, that there being interspersed Vacuities as well in the rest of the Air that was very near the Water, as in that contained in the Vial, there was no reason, why the Water should ascend to fill the Vacuities of one portion of Air rather than those of another. But when once by suction a great many of the Aerial Corpuscles were made to pass out of the Vial, the Spring of the remaining Air being weakened, whilst the pressure of the ambient Air, which depends upon its constant Gravity, is undiminished, the Spring of the internal becomes unable to resist the weight of the external Air, which is therefore able to impel the interposed Water with some violence into the Cavity of the Glass, till the Air, remaining in that Cavity, being reduced almost to its usual Density, is able by its Spring, and the weight of the Water got up into the Vial, to hinder any more Water from being impelled up. For, as to what Mr. Hobbes affirms, that, Is qui sugit Phialam neque in ventrem quicquam, neque in pulmones, neque in as quicquam exugit: How it will agree with what he elsewhere delivers about Suction, I leave him to consider. But I confess, I cannot but wonder at his confidence, that can positively assert a thing so repugnant to the common sentiments of Men of all opinions, without offering any proof for it. But I suppose, they that are by trial acquainted with Sucking, and have felt the Air come in at their mouths, will prefer their own experience to his authority. And as to what he adds, that the Person that sucks agitates the Air, and turns it within the Vial into a kind of circulating wind, that endeavours every where to get out; I wish, he had shown us by what means a Man that sucks makes this odd Commotion of the Air; especially in such Vials as I use to employ about the Experiment, the orifice of whose neck is sometimes less than a Pins head.  A. 
That there may be really Air extracted by Suction out of a Glass, me thinks you might argue from an Experiment I saw you make with a Receiver which was exhausted by your Pump, and consequently by Suction. For I remember, when you had counterpoised it with very good Scales, and afterwards by turning a stop-cock, let in the outward Air, there rushed in as much Air to fill the space that had been deserted by the Air pump● out, as weighed some scruples (consisting of twenty grains a piece) though the Receiver were not of the largest size.  B. 
You did well to add that Clause; for, the Magdeburgic Experiment, mentioned by the industrious Schottus, having been made with a vast Receiver, the readmitted Air amounted to a whole ounce and some drachms. But to return to Mr. Hobbes, I fear not that he will persuade you, that have seen the Experiment he recites, that as soon as the neck of the Vial is unstopped under water, the Air, that whirled about before, makes a sally out, and forces in as much water. For, if the orifice be any thing large, you will, instead of feeling an endeavour to thrust away your finger that stopped it, find the pulp of your finger so thrust inward, that a Peripatetic would affirm that he felt it sucked in. And that Intrusion may be the Reason, why the lip of him that sucks is oftentimes strongly fastened to the orifice of the Vials neck, which Mr. Hobbes ascribes to a most exquisite contact, but without clearly telling us, how that extraordinary contact is effected. And when your finger is removed, instead of perceiving any Air go out of the Vial through the water, (which, if any such thing happen, you will easily discover by the bubbles,) you shall see the water briskly spring up in a slender stream to the top of the Vial, which it could not do, if the Cavity were already full of Air. And to let you see, that, when the Air does really pass in or out of the Vial immersed under water, 'tis very easy to perceive its motions, if you dip the neck of the Vial in water, and then apply to the globulous part of it either your warm hands or any other competent Heat, the internal Air being rarified; you shall see a portion of it, answerable to the degree of Heat you applied, manifestly pass through the water in successive bubbles, whilst yet you shall not see any water get into the Vial to supply the place deserted by that Air. And if, when you have (as you may do by the help of sucking) filled the neck and part of the belly of the Vial with water, you immerse the orifice into stagnant water, and apply warm hands to the globulous part as before, you will find the water in the Vial to be driven out, before any bubbles pass out of the Vial into the surrounding water; which shows, that the Air is not so forward to dive under the water, (and much less under so ponderous a liquor as Quicksilver,) as Mr. Hobbes has supposed.  A. 
That 'tis the Pressure of the external Air, that (surmounting the Spring of the internal) drives up the water into the Vial we have been speaking of, does, I confess, follow upon your Hypothesis: But an Experimentarian Philosopher, as Mr. Hobbes calls you among others, may possibly be furnished with an Experiment to confirm this to the Eye.  B. 
You bring into my mind what I once devised to confirm my Hypothesis about Suction, but found a while since that I had omitted it in my Discourse about that Subject. And therefore I shall now repeat to you the substance at least of the Memorial that was written of that Experiment, by which the great interest of the weight of the Atmospherical Air in Suction will appear, and in which also some things will occur, that will not well agree with Mr. Hobbes' Explication, and prevent some of his Allegations against mine.  A. 
Having not yet met with an Experiment of this nature, such an one as you speak of will be welcome to me.  B. 
We took a Glass Bubble, whose long stem was both very slender and very Cylindrical; then by applying to the outside of the Ball or globulous part a convenient heat, we expelled so much of the Air, as that, when the end of the pipe was dipped in water, and the inward Air had time to recover its former coolness, the water ascended either to the top of the pipe or very near it. This done, we gently and warily rarified the Air in the Cavity of the Bubble, till by its expansion it had driven out almost all the water that had got up into the stem, that so it might attain as near as could be to that degree of heat and measure of expansion, that it had when the water began to rise in it. And we were careful to leave two or three drops of water unexpelled at the bottom of the pipe, that we might be sure, that none of the included Air was by this second rarefaction driven out at the orifice of it; as the depression of the water so low assured us, on the other side, that the included Air wanted nothing considerable of the expansion it had when the water began to ascend into the pipe. Whilst the Air was in this rarified state, we presently removed the little Instrument out of the stagnant water into stagnant Quicksilver, which in a short time began to rise in the pipe. Now, if the ascension of the liquor were the effect of Nature's Abhorrence of a Vacuum; or of some internal principle of Motion; or of the Compression and propagated Pulsion of the outward Air by that which had been expelled; why should not the Mercury have ascended to the top of the pipe, as the water did before? But de facto it did not ascend half, or perhaps a quarter so far; and if the pipe had been long enough, as well as 'twas slender enough, I question, whether the Mercury would have ascended (in proportion to the length of the stem) half so high as it did.  
Now of this Experiment, which we tried more than once, I see not, for the reason lately expressed, how any good account will be given without our Hypothesis, but according to That 'tis clear.  A. 
I think I perceive why you say so; for the Ascension of Liquors being an effect of the prevalency of the external Airs pressure against the resistance it meets with in the Cavity of the Instrument, and the Quicksilver being bulk for bulk many times heavier than water, the same surplusage of pressure that was able to impel up water to the top of the pipe, ought not to be able to impel up the Quicksilver to any thing near that height. And if it be here objected, as it very plausibly may be, that the raised Cylinder of Mercury was much longer than it ought to have been in reference to a Cylinder of Water, the proportion in gravity between those two Liquors (which is almost that of fourteen to one) being considered; I answer, that when the Cylinder of Water reached to the pipe, the Air possessed no more than the Cavity of the globulous part of the Instrument, being very little assisted to dilate itself by so light a Cylinder as that of Water: But when the Quicksilver came to be impelled into the Instrument by the weight of the external Air, that ponderous Body did not stop its ascent as soon as it came to be equiponderant to the formerly expelled Cylinder of Water; because, to attain that height, it reached but a little way into the pipe, and left all the rest of the Cavity of the pipe to be filled with part of that Air, which formerly was all s●ut up in the Cavity of the Bubble; by which means the Air, included in the whole Instrument, must needs be in a state of expansion, and thereby have its Spring weakened, and consequently disabled to resist the pressure of the external Air, as much as the same included Air did before, when it was less rarified; on which account, the undiminished weight or pressure of the external Air was able to raise the Quicksilver higher and higher, till it had obtained that height, at which the pressure, compounded of the weight of the Mercurial Cylinder and the Spring of the internal Air (now less rarified than before,) was equivalent to the pressure of the Atmosphere or external Air.  B. 
You have given the very Explication I was about to propose; wherefore I shall only add, that to confirm this Experiment by a kind of Inversion of it, we drove by heat a little Air out of the Bubble, and dipped the open end of the pipe into Quicksilver, which by this means we made to ascend till it had filled about a fourth part or less of the pipe, when that was held erected. Then carefully removing it without letting fall any Quicksilver, or letting in any Air, we held the orifice of the pipe a little under the surface of a Glass full of Water, and applying a moderate heat to the outside of the Ball, we warily expelled the Quicksilver, yet leaving a little of it to make it sure that no Air was driven out with it, then suffering the included Air to cool, the external Air was found able to make the Water not only ascend to the very top of the pipe, and thence spread itself a little into the Cavity of the Ball, but to carry up before it the Quicksilver that had remained unexpelled at the bottom of the stem. And if in making the Experiment we had first raised, as we sometimes did, a greater quantity of Quicksilver, and afterwards drove it out, the quantity of Water, that would be impelled into the Cavity of the pipe and ball, would be accordingly increased.  A. 
In this Experiment 'tis manifest, that something is driven out of the Cavity of the Glass before the Water or Quicksilver begins to ascend in it: And here also we see not, that the Air can pass through the pores of Quicksilver or Water, but that it drives them on before it, without sensibly mixing with them. In this Experiment there appears not at all any Circular Wind, as Mr. Hobbes fancies in the sucked Vial we are disputing of, nor any tendency outwards of the included Air upon the account of such a Wind; but, instead of these things, that the ascension of the Liquors into the Cavity of the pipe depends upon the external Air, pressing up the Liquors into that Cavity, may be argued by this, that the same weight of the Atmosphere impelled up into the pipe so much more of the lighter Liquor, Water, than of the heavier Liquor, Mercury.  B. 
You have said enough on this Experiment; but 'tis not the only I have to oppose to Mr. Hobbes his Explication: For, that there is no need of the sallying of Air out of a Vial, to make the Atmospherical Air press against a Body that closes the orifice of it, when the pressure of the internal Air is much weakened; I have had occasion to show some Virtuosos, by sucking out, with the help of an Instrument, a considerable portion of the Air contained in a Glass; for having then, instead of unstopping the orifice under water, nimbly applied a flat Body to it, the external Air pressed that Body so forcibly against it, as to keep it fastened and suspended, though 'twere clogged with a weight of many ounces.  A. 
Another Experiment of yours Mr. Hobbes' Explication brings into my mind, by which it appears, that, if there be such a Circular Wind, as he pretends, produced by Suction in the Cavity of the Vial, it must needs be strangely lasting. For I have seen more than once, that, when you have by an Instrument sucked much of the Air out of a Vial, and afterwards carefully closed it, though you kept the slender neck of it stopped a long time, perhaps for some weeks or months, yet when 'twas opened under water, a considerable quantity of the Liquor would be briskly impelled up into the neck and belly of the Vial. So that, though I will not be so pleasant with Mr. Hobbes, as to mind you on this occasion of those Writers of Natural Magic, that teach us to shut up Articulate Sounds in a Vessel, which being transported to a distant place and opened there, will rende● the Words that are committed to it● yet I must needs say, that so lasting a Circular Wind, as, according to Mr. Hobbes, your Experiments exhibited, may well deserve our wonder.  B. 
Your admiration would perchance increase, if I should assure you, that having with the Sunbeams produced smoke in one of those well-stopped Vials, this Circular Wind did not at all appear to blow it about, but suffered it to rise, as it would have done if the included Air had been very calm. And now I shall add but one Experiment more, which will not be liable to some of the things as invalid as they are, which Mr. Hobbes has alleged in his account of the Vial, and which will let you see, that the weight of the Atmospherical Air is a very considerable thing; and which may also incline you to think, that, whilst Mr. Hobbes does not admit a subtler Matter than common Air to pass through the Pores of close and solid Bodies, the Air he has recourse to will sometimes come too late to prevent a Vacuum. The Experiment, which was partly accidental, I lately found registered to this sense, if not in these words: [Having, to make some Discovery of the weight of the Air, and for other purposes, caused an AEolipile, very light considering its bulk, to be made by a famous Artist, I had occasion to put it so often into the fire for several Trials, that at length the Copper scaled off by degrees, and left the Vessel much thinner than when it first came out of the Artificers hands; and a good while after, this change in the Instrument being not in my thoughts, I had occasion to employ it, as formerly, to weigh how many grains it would contain of the Air at such a determinate constitution of the Atmosphere, as was to be met with, where I than chanced to be. For the making this Experiment the more exactly, the Air was by a strong, but warily applied, fire so carefully driven away, that, when clapping a piece of Sealing-wax to the Pin-hole, at which it had been forced out, we hindered any communication betwixt the Cavity of the Instrument and the external Air, we supposed the AEolipile to be very well exhausted, and therefore laid it by, that, when it should be grown cold, we might, by opening the orifice with a Pin, again let in the outward Air, and observe the increase of weight that would thereupon ensue: But the Instrument, that, as I was saying, was grown thin, had been so diligently freed from Air, that the very little that remained, and was kept by the War from receiving any assistance from without, being unable by its Spring to assist the AEolipile to support the weight of the ambient Air; this external fluid did by its weight press against it so strongly, that it compressed it, and thrust it so considerably inwards, and in more than one place so changed its figure, that, when I showed it to the Virtuosos that were assembled at Gresham-Colledge, they were pleased to command it of me to be kept in their Repository, where I presume it is still to be seen.  
FINIS.   

OF THE CAUSE OF Attraction BY SUCTION.  
By the Honourable ROBERT boil, Fellow of the Royal Society.  
LONDON, Printed by William Godbid, and are to be Sold by Moses Pitt, at the Angel over against the little North Door of St. Paul's Church. 1674.   

PREFACE.  
HAving about twelve years ago summarily expressed and published my Opinion of the Cause of Suction, and a while before or after brought to the Royal Society the Glass Instrument I employed to make it out; I desisted for some time to add any thing about a Problem, that I had but occasionally handled: Only, because the Instrument I mentioned in my Examen of Mr. Hobbes' Opinion, and afterwards used at Gresham-College, was difficult enough to be well made, and not to be procured ready made, I did for the sake of some Virtuosos, that were curious of such things, devise a slight and easily made Instrument, described in the following Tract, Chap. 4th, in which the chief Phaenomena, I showed before the Society, were easily producible. But afterwards the mistakes and erroneous Opinions, that, in Print as well as in Discourse, I met with, even among Learned Men, about Suction, and the Curiosity of an Ingenious Person, engaged me to resume that Subject and treat of it, as if I had never before meddled with it, for the reason intimated in the beginning of the ensuing Paper. And finding upon the review of my later Animadversions an Mr. Hobbes's Problemata de Vacuo, that some passages of this Tract are referred to there; I saw myself thereby little less than engaged to annex that Discourse to those Animadversions. And this I the rather consented to, because it contains some Experiments, that I have not elsewhere met with, which, together with some other parts of that Essay, may, I hope, prove of some use to illustrate and confirm our Doctrine about the Weight and Spring of the Air, and supply the less experienced than ingenious. Friends to our Hypothesis with more grounds of answering the later Objections of some Learned Men, against whose endeavours I perceive it will be useful to employ variety of Experiments and other Proofs to evince the same Truth; that some or other of these may meet with those Arguments or evasions with which they strive to elude the force of the rest.  
The Title of the following Essay may sufficiently keep the Reader from expecting to find any other kind of Attraction discoursed of, than that which is made by Suction. But yet thus much I shall here intimate in general, that I have found by Trials purposely made, that the Examples of Suction are not the only noted ones of Attraction, that may be reduced to Pulsion.   

OF THE CAUSE OF ATTRACTION BY SUCTION.  

CHAP. I.  
I Might, Sir, save myself some trouble in giving you that account you desire of me about Suction, by referring you to a passage in the Examen, I long since writ, of Mr. Hobbes' Dialogus Physicus de Natura Aeris, if I knew, you had those two Books lying by you. But because I suspect, that my Examen may not be in your hands, since 'tis a most out of Print, and has not for some years been in my own; and because I do not so well remember, after so long a time the particulars that I writ there, about Suction, as I do in general, that the Hypothesis I proposed, was very incidentally and briefly discoursed of, upon an occasion ministered by a wrong Explication given of Suction by Mr. Hobbes, I shall here decline referring you to what I there writ● and proposing to you those thoughts about Suction, that I remember I there pointed at, I shall annex some things to illustrate and confirm them; that would not have been so proper for me to have insisted on in a short and but occasional Excursion.  
And I should immediately proceed to what you expect from me, but that Suction being generally looked upon as a kind of Attraction, it will be requisite for me to premise something about Attraction itself. For, besides that the Cause of it, which I here dispute not of, is obscure, the very Nature and Notion of it is wont by Naturalists to be either left untouched, or but very darkly delivered, and therefore will not be unfit to be here somewhat explained.  
How general and ancient soever the common Opinion may be, that Attraction is a kind of Motion quite differing from Pulsion, if not also opposite to it; yet I confess, I concur in opinion, though not altogether upon the same grounds, with some modern Naturalists, that think Attraction a Species of Pulsion. And at least among inanimate Bodies I have not yet observed any thing, that convinces me, that Attraction cannot be reduced to Pulsion; for, these two seem to me to be but extrinsical denominations of the same Local Motion, in which, if a moved Body precede the Movent, or tend to acquire a greater distance from it, we call it Pulsion; and if, upon the score of the Motion, the same Body follow the Movent or approach to it, we call it Attraction. But this difference may consist but in an accidental respect, which does not Physically alter the nature of the Motion, but is founded upon the respect, which the Line, wherein the Motion is made, happens to have to the situation of the Movent. And that which seems to me to have been the chief cause of men's mistaking Attraction for a motion opposite to Pulsion, is, that they have looked upon both the moving and moved Bodies, in too popular and superficial a manner; and considered in the Movent rather the situation of the conspicuous and more bulky part of the Animal or other Agent, than the situation of that part of the Animal, or Instrument, that does immediately impress that motion upon the Mobile.  
For those that attentively heed this, may easily take notice, that some part of that Body, or of the Instrument, which by reason of their conjunction in this operation is to be looked on but as making one with it, is really placed behind some part of the Body to be drawn, and therefore cannot move outwards itself without thrusting that Body forward. This will be easily understood, if we consider, what happens when a Man draws a Chain after him; for, though his Body do precede the Chain, yet his finger or some other part of the hand, wherewith he draws it, has some part or other that reaches behind the fore part of the first Link, and the hinder part of this Link comes behind the anteriour part of the second Link; and so each Link has one of its parts placed behind some part of the Link next after it, till you come to the last Link of all. And so, as the finger, that is in the first Link, cannot move forwards but it must thrust on that Link, by this Series of Trusions the whole Chain is moved forwards; and if any other Body be drawn by that Chain, you may perceive, that some part of the last Link comes behind some part of that Body, or of some intervening Body, which, by its cohesion with it, aught in our present case to be considered as part of it. And thus Attraction seems to be but a Species of Pulsion, and usually belongs to that kind of it, which, for distinctions sake, is called Trusion, by which we understand that kind of Pulsion, wherein the Movent goes along with the moved Body without quitting it whilst the progress lasts; as it happens, when a Gardener drives his Wheel-barrow before him without letting go his hold of it.  
But I must not here dissemble a difficulty, that I foresee may be speciously urged against this account of Attraction. For it may be said, that there are Attractions, where it cannot be pretended, that any part of the Attrahent comes behind the Attracted Body; as in Magnetical and Electrical Attractions, and in that which is made of Water, when 'tis drawn up into Springs and Pumps.  
I need not tell you, that you know so well, as that partly the Cartesians, and partly other Modern Philosophers, have recourse on this occasion either to screwed Particles and other Magnetical Emissions, to explicate Phaenomena of this kind. And, according to such Hypotheses, one may say, that many of these Magnetical and Electrical Effluvia come behind some parts of the attracted Bodies, or at least of the little solid Particles, that are as it were the Walls of their ●ores, or procure some discussion of the Air, that may make it thrust the Movable towards the Loadstone or Amber, etc. But if there were none of these, nor any other subtle Agents that cause this Motion by a real, though unperceived, Pulsion; I should make a distinction betwixt other Attractions and these, which I should then style Attraction by Invisibles. But, whether there be really any such in Nature, and why I scruple to admit things so hard to be conceived, may be elsewhere considered. And you will, I presume, the freelier allow me this liberty, if, (since in this place 'tis proper to do it,) I show you, that in the last of the instances I formerly objected (that of the drawing up of Water into the Barrel of a Syringe,) there is no true Attraction of the Liquor made by the external Air. I say then, that by the ascending Rammer, as a part of which I here consider the obtuse end, Plug, or Sucker, there is no Attraction made of the contiguous and subjacent Water, but only there is room made for it, to rise into, without being exposed to the pressure of the superior Air. For, if we suppose the whole Rammer to be by Divine Omnipotence annihilated, and consequently uncapable of exercising any Attraction; yet, provided the superior Air were kept off from the Water by any other way as well as 'twas by the Rammer, the Liquor would as well ascend into the Cavity of the Barrel; since, (as I have elsewhere abundantly proved,) the surface of the Terraqueous Globe being continually pressed on by the incumbent Air or Atmosphere, the Water must be by that pressure impelled into any cavity here below, where there is no Air to resist it; as by our Supposition there is not in the Barrel of our Syringe, when the Rammer, or whatever else was in it, had been annihilated. Which Reasoning may be sufficiently confirmed by an Experiment, whereby I have more than once shown some curious persons, that, if the external Air, and consequently its pressure, be withdrawn from about the Syringe, one may pull up the Sucker as much as he pleases, without drawing up after it the subjacent Water. In short, let us suppose, that a Man standing in an inner room does by his utmost resistance keep shut a Door, that is neither locked nor latched, against another, who with equal force endeavours to thrust it open? In this case, as if one should forcibly pull away the first Man, it could not be said, that this Man, by his recess from the Door he endeavoured to press outwards, did truly and properly draw in his Antagonist, though upon that recess the coming in of his Antagonist would presently ensue; so it cannot properly be said, that by the ascent of the Rammer, which displaces the superior Air, either the Rammer itself, or the expelled Air, does properly attracts the subjacent Water, though the ingress of that Liquor into the Barrel does thereupon necessarily ensue. And that, as the Comparison supposes, there is a pressure of the superior Air against the upper part of the Sucker, you may easily perceive, if having well stopped the lower orifice of the Syringe with your finger, you forcibly draw up the Sucker to the top of the Barrel. For if then you let go the Rammer, you will find it impelled downwards by the incumbent Air with a notable force.   

CHAP. II.  
HAving thus premised something in general about the Nature of Attraction, as far as 'tis necessary for my present design; it will be now seasonable to proceed to the consideration of that kind of Attraction, that is employed to raise Liquors, and is by a distinct Name called Suction.  
About the Cause of this there is great comention between the New Philosophers; as they are styled, and the Peripatetics. For the Followers of Aristotle, and many Learned Men that in other things descent from him, ascribe the ascension of Liquors upon Suction to Nature's abhorrence of a Vacuum. For, say they, when a Man dips one end of a Straw or Reed into stagnant Water, and sucks at the other end, the Air contained in the cavity of the Reed passes into that of his Lungs, and consequently the Reed would be left empty, if no other Body succeeded in the place it deserts; but there are only (that they take notice of,) two Bodies that can succeed, the Air and the (grosser Liquor) the Water; and the Air cannot do it, because of the interposition of the Water, that denies it access to the immersed orifice of th● Reed, and therefore it must be the Water itself, which accordingly does ascend to prevent a Vacuum detested by Nature.  
But many of the Modern Philosophers, and generally all the Corpusc●larians, look upon this Fuga Vacue as but an imaginary Cause of Suction; though they do it upon very differing grounds. For, the Atomists; tha● willingly admit of Vacuities, properly so called, both within and without our World, cannot think that Nature hates or fears a Vacuum, and declines her usual course to prevent it: And the Cartesians, though they do, as well as the Peripatetics, deny that that there is a Vacuum, yet since they affirm not only, that there is none in rerum Natura, but that there can be none, because what others call an empty Space having three Dimensions, hath all that they think belonging to the Essence of a Body, they will not grant Nature to be so indiscreet, as to strain herself to prevent the making of a thing that is impossible to be made.  
The Peripatetic Opinion about the Cause of Suction, though commonly defended by the Schools, as well Modern as Ancient, supposes in Nature such an abhorrence of a Vacuum, as neither has been well proved, nor does well agree with the lately discovered Phaenomenon of Suction. For, according to their Hypothesis, Water and other Liquors should ascend upon Suction to any height to prevent a Vacuum, which yet is not agreeable to experience. For I have carefully tried, that by pumping with a Pump far more staunch than those that are usually made, and indeed as well closed as we could possibly bring it to be, we could not by all our endeavours raise Water by Suction to above 
* See Cont. of Phys. Mech. Exp. the 15 th' Exp.  36 ½ foot. The Torricellian Expt shows, tha● the weight of the Air is able to sustain, and some of our Experim ts show, 'tis able to raise a Mercurial Cylinder equal in weight to as high a Cylinder of Water as we were able to raise by pumping. For Mercury being near ●● times as heavy as Water of the sam● bulk, if the weight of the Air b● equivalent to that of a Mercuri● Cylinder of 29 or 30 Inches, it mu●● be able to counterpoise a Cylinder o● Water near fourteen times as long that is, from thirty four to near thirt● six foot. And very disagreeable t● the common Hypothesis, but consonant to ours, is the Experiment th● I have more than once tried, and ● think elsewhere delivered, namely That, if you take a Glass Pipe of a●bout three foot long, and, dipping one end of it in Water, suck at the other, the Water will be suddenly made to flow briskly into your mouth: But, if instead of Water you dip the lower end into Quicksilver, though you suck as strongly as ever you can, provided that in this case, as in the former, you hold the Pipe upright, you will never be able to suck up the Quicksilver near so high as your mouth; so that if the Water ascended upon Suction to the top of the same Pipe, because else there would have been a Vacuum left in the cavity of it, why should not we conclude, that, when we have sucked up the Quicksilver as strongly as we can, as much of the upper part of the Tube as is deserted by the Air, and yet not filled by the Mercury, admits, in part at least, a Vacuum, (as to Air) of which consequently Nature cannot reasonably be supposed to have so great and unlimited an abhorrency, as the Peripatetics and their Adherents presume. Yet I will not determine, whether there be any more than many little Vacuities, or Spaces devoid of Air, in the Cavity; so called, of the Pipe unfilled by the Mercury; (so that the whole Cavity is not one entire empty Space;) it being sufficient for my purpose, that my Experiment affords a good Argument ad hominem against the Peripatetics, and warrants us to seek for some other Cause than the fuga Vacui, why a much stronger Suction than that, which made Water ascend with ease into the Suckers mouth, will not also raise Quicksilver to the same height or near it.  
Those Modern Philosophers that admit not the fuga Vacui to be the Cause of the raising of Liquors in Suction, do generally enough agree in referring it to the action of the Suckers thorax. For, when a Man endeavours to suck up a Liquor, he does by means of the Muscles enlarge the cavity of his Chest, which he cannot do but at the same time he must thrust away those parts of the ambient Air that were contiguous to his Chest, and the displaced Air does, according to some Learned Men, (therein, if I mistake not, Follower's of Gassendus,) compress the contiguous Air, and that the next to it, and so outwards, till the pressure, successively passing from one part of the Air to the other, arrive at the surface of the Liquor; and all other places being as to sense full, the impelled Air cannot find place but by thrusting the Water into the room made for it in the Pipe by the recess of the Air that passed into the Suckers lungs. And they differed not much from this Explication, that, without taking in the compression of the ambient Air made by the thorax, refer the Phaenomenon to the propagated motion or impulse, that is impressed on the Air displaced by the thorax in its dilatation, and yet unable to move in a World perfectly filled, as they suppose ours to be, unless the Liquor be impelled into as much of the cavity of the Pipe, as fast as 'tis deserted by the Air that is said to be sucked up. But though I readily confess this Explication to be ingenious, and such as I wonder not they should acquiess in, who are acquainted but with the long known and obvious Phaenomena of Suction; and though I am not sure, but that in the most familiar cases the Causes assigned by them may contribute to the Effect; yet, preserving for Cartesius and Gassendus the respect I willingly pay such great Philosophers, I must take the liberty to tell you, that I cannot acquiess in their Theory. For I think, that the Cause of Suction, they assign, is in many cases not necessary, in others, not sufficient. And first, as to the Condensation of the Air by the dilatation of the Suckers Chest; when I consider the extent of the ambient Air, and how small a compression no greater an expansion than that of the Thorax is like to make, I can scarce think, so slight a condensation of the free Air can have so considerable an operation on the surface of the Liquor to be raised, as the Hypothesis I examine requires: And that this impulse of the Air by a Suckers dilated Thorax, though it be wont to accompany the ascension of the water procured by Suction, yet is not of absolute necessity to it, will, I presume, be easily granted, if it can be made out, that even a propagated Pulsion, abstracted from any Condensation of Air, is not so necessarily the Cause of it, but that the Effect may be produced without it. For suppose, that by Divine Omnipotence so much Air as is displaced by the Thorax were annihilated; yet I see not, why the Ascension of the Liquor should not ensue. For, when a Man begins to suck, there is an AEquilibrium, or rather AEquipollency between the pressure, which the Air, contained in the Pipe, (which is shut up with the pressure of the Atmosphere upon it,) has, by virtue of its Spring, upon that part of the surface of the water that is environed by the sides of the Pipe, and the pressure which the Atmospherical Air has, by virtue of its weight, upon all the rest of the surface of the stagnant water; so that, when by the dilatation of the Suckers Thorax, the Air within the cavity of the Pipe comes to be rarified, and consequently lose of its Spring, the weight of the external Air continuing in the mean time the same, it must necessarily happen, that the Spring of the internal Air will be too weak to compress any longer the gravitation of the external, and consequently, that part of the surface of the stagnant water, that is included in the Pipe, being less pressed upon, than all the other parts of the same surfaces must necessarily give way, where it can least, resist, and consequently be impelled up into the Pipe, where the Air, having had its Spring weakened by expansion, is no longer able to resist, as it did before. This may be illustrated by somewhat varying an Instance already given, and conceiving, that within a Chamber three Men thrust all together with their utmost force against a Door, (which we suppose to have neither Bolt nor Latch) to keep it shut, at the same time the three other Men have just equal strength, and employ their force to thrust it open. For though, whilst their opposite endeavours are equal, the Door will continue to be kept shut, yet if one of the three Men within the Room should go away, there will need no new force, nor other accession of strength to the three Men, to make them prevail and thrust open the Door against the resistance of those that endeavoured to keep it shut, who are now but two.  
And here (upon the by) you may take notice, that, to raise water in Suction, there is no necessity of any rarified and forcibly stretched Rope, as 'twere, of the Air, to draw up the subjacent water into the Pipe, since the bare debilitation of the Spring of the included Air may very well serve the turn. And though, if we should suppose the Air within the Pipe to be quite annihilated, it could not be pretended (since it would not have so much as Existence) that it exercises an attractive Power; yet in this case the water would ascend into the Pipe, without the assistance of Nature's imaginary Abhorrence of a Vacuum, but by a Mechanical Necessity, plainly arising from this, that there would be a pressure of the incumbent Atmosphere upon the rest of the surface of the stagnant water, and no pressure at all upon that part of the surface that is within the Pipe, where consequently there could be no resistance made to the ascension of the water, every where else strongly urged by the weight of the incumbent Air.  
I shall add on this occasion, that, to show some inquisitive Men, that the weak resistance within a Vessel, that had but one orifice exposed to the water, may much more contribute to the ascension of that Liquor into the Vessel, than either the compression or the continued or reflected impulse of the external Air; I thought fit to produce a Phaenomenon, which by the Beholders was without scruple judged an Effect of Suction, and yet could not be ascribed to the Cause of Suction, assigned by either of the Sects of Philosophers I descent from. The Experiment was this: By a way, elsewhere delivered, the long neck of a Glass-bubble was sealed up, and almost all the Air had been by Heat driven out of the whole cavity of the Bubble or Vial, and then the Glass was laid aside for some hours, or as long as we pleased; afterwards the sealed apex of the neck was broken off under water: I demand now of a Peripatetic, whether the Liquor ought to be sucked or drawn into the cavity of the Glass, and why? if he says, as questionless he will, that the water would be attracted to hinder a Vacuum, he would thereby acknowledge, that, till the Glass was unstopped under water, there was some empty space in it; for, till the sealed end was broken off, the water could not get in, and therefore, if the fuga vacui had any thing to do in the ascension, the Liquor must rise, not to prevent an empty space, but to fill one that was made before. Nor does our Experiment much more favour the other Philosophers, I descent from: For in it there is no dilatation made of the sides of the Glass, as in ordinary Suction there is made of the Thorax, but only there is so much Air driven out of the cavity of the Bubble, into whose room since neither common Air nor Water is permitted to succeed, it appears not, how the propagated and returning impulse, or the Circle of Motion, as to common Air and Water, does here take place. And then I demand, what becomes of the Air, that has been by heat driven out, and is by the Hermetical Seal kept out of the cavity of the Bubble? If it be said, that it diffuses itself into the ambient Air, and mingles with it, that will be granted which I contended for, that so little Air as is usually displaced in Suction cannot make any considerable compression of the free ambient Air; for, what can one Cubic Inch of Air, which is sometimes more than one of our Glasses contains, do, to the condensation so much as of all the Air in the Chamber, when the expelled Corpuscles are evenly distributed among those of the ambient. And how comes this inconsiderable condensation to have so great an effect in every part of the room, as to be able there to impel into the Glass as much water in extent as the whole Air that was driven out of the cavity of it? But if it be said, that the expelled Air condensed only the contiguous or very neighbouring Air, 'tis easy to answer, that 'tis no way probable, that the expelled Particles of the Air should not by the differing motions of the ambient Air be quickly made to mingle with it, but should rather wait (which if it did we sometimes made it do for many hours) till the Vessels whence 'twas driven out were unstopped again. But, though this could probably be pretended, it cannot truly be asserted. For if you carry the sealed Glass quite out of the room or house, and unstop it at some other place, though two or three miles distant; the ascension of the water will, (as I found by trial) nevertheless ensue; in which case I presume, it will not be said, that the Air, that was expelled out of the Glass, and condensed the contiguous or near contiguous Air, attended the Bubble in all its motions, and was ready at hand to impel-in the water, as soon as the sealed apex of the Vial was broken off. But I doubt not, but most of the Embracers of the Opinion I oppose, being Learned and Ingenuous Persons, if they had been acquainted with these and the like Phaenomena, would rather have changed their Opinion about Suction, than have gone about to defend it by such Evasions, which I should not have thought worth proposing, if I had not met with Objections of this nature publicly maintained by a Learned Writer, on occasion of the Air's rushing into the exhausted Magdenburgic Engine. But as in our Experiment these Objections have no place, so in our Hypothesis the Explication is very easy, as will anon be intimated.   

CHAP. III.  
HAving thus shown, that the Ascension of Water upon Suction may be caused otherwise than by the Condensation or the propagated Pulsion of Air contiguous to the Suckers Thorax, and thrust out of place by it; it remains that I show, (which was one of the two things I chiefly intended,) that there may be Cases wherein the Cause, assigned in the Hypothesis I am examining, will not have place. But this will be better understood, if, before I proceed to the proof of it, I propose to you the thoughts, I had many years since, and do still retain, about the Cause of the Ascension of Liquors in Suction.  
To clear the way to the right understanding of the ensuing Discourse, it will not be amiss here to premise a summary intimation of some things that are supposed in our Hypothesis.  
We suppose then first, without disputing either the Existence or the nature of Elementary Air, that the Common Air we breath in, and which I often call Atmospherical Air, abounds with Corpuscles not devoid of Weight, and endowed with Elasticity or Springiness, whereby the lower parts, compressed by the weight of the upper, incessantly endeavour to expand themselves, by which expansion, and in proportion to it, the Spring of the Air is weakened, (as other Springs are wont to be) the more they are permitted to stretch themselves.  
Next, we suppose, that the Terraqueous Globe, being environed with this gravitating and springy Air, has its surface and the Bodies placed on it pressed by as much of the Atmosphere as either perpendicularly leans on them, or can otherwise come to bear upon them. And this pressure is by the Torricellian and other Experiments found to be equivalent to a perpendicularly erected Cylinder of about twenty nine or thirty Inches of Quicksilver, (for the height is differing, as the gravity of the Atmosphere happens to be various.)  
Lastly, we suppose, that, Air being contained in a Pipe or other hollow Body that has but one orifice open to the free Air, if this orifice be Hermetically sealed, or otherwise (as with the mouth of one that sucks) closed, the now included Air, whilst it continues without any farther expansion, will have an elasticity equivalent to the weight of as much of the outward Air as did before press against it. For, if the weight of the Atmosphere, to which it was then exposed, had been able to compress it further, it would have done so, and then the closing of the orifice, at which the internal and external Air communicated, as it fenced the included Air from the pressure of the incumbent, so it hindered the same included Air from expanding itself; so that, as it was shut up with the pressure of the Atmosphere upon it, that is in a state of as great compression as the weight of the Atmosphere could bring it to, so, being shut up and thereby kept from weakening that pressure by expansion, it must retain a Springiness equipollent to the pressure 'twas exposed to before, which (as I just now noted) was as great as the weight ● the incumbent Pillar of the Atmosphere could make it. But if, as was said in the first Supposition, the included Air should come to be dilated or expanded, the Spring being then unbent, its Spring, like that of other elastical Bodies, would be debilitated answerably to that expansion.  
To me than it seems, that, speaking in general, Liquors are upon Suction raised into the cavities of Pipes and other hollow Bodies, when, and so far as, there is a less pressure on the surface of the Liquor in the cavity, than on the surface of the external Liquor that surrounds the Pipe, whether that pressure on those parts of the external Liquor, that are from time to time impelled up into the orifice of the Pipe, proceed from the weight of the Atmosphere, or the propagated compression or impulse of some parts of the Air, or the Spring of the Air, or some other Cause, as the pressure of some other Body quite distinct from Air.  
Upon the general view of this Hypothesis, it seems very consonant to the Mechanical Principles. For, if there be on the differing parts of the surface of a fluid Body unequal pressures, 'tis plain, as well by the nature of the thing, as by what has been demonstrated by Archimedes, and his Commentators, that the greater force will prevail against the lesser, and that that part of the waters surface must give way, where it is least pressed. So that that, wherein the Hypothesis I venture to propose to you, differs from that which I descent from, is not, that mine is less Mechanical; but partly in this, that, whereas the Hypothesis, I question, supposes a necessity of the protrusion or impulse of the Air, mine does not require that supposition, but, being more general, reaches to other ways of procuring the Ascension of Liquors, without raising them by the impulse of the Air; and partly, and indeed chiefly, in that the Hypothesis, I decline, makes the Cause of the Ascension of Liquors to be only the increased pressure of the Air external to the pipe; and I chiefly make it to depend upon the diminished pressure of the Air within the pipe, on the score of the expansion 'tis brought to by Suction.  
To proceed now to some Experiments that I made in favour of this Hypothesis, I shall begin with that which follows:  
We took a Glass-pipe bended like a Syphon, but so that the shorter leg was as parallel to the longer as we could get it made, and was Hermetically sealed at the end: Into this Syphon we made a shift (for 'tis not very easy) to convey water, so that the crooked part being held downwards, the liquor reached to the same height in both the legs, and yet there was about an Inch and half of uncomprest Air shut up in the shorter leg. This little Instrument (for 'twas but about fifteen Inches long) being thus prepared, 'tis plain, that according to the Hypothesis I descent from, there is no reason, why the water should ascend upon Suction. For, though we should admit, that the external Air were considerably compressed, or received a notable impulse, when the Suckers chest is enlarged; yet in our case that compression or protrusion will not reach the surface of the water in the shorter leg, because it is there fenced from the action of the external Air by the sides of the Glass, and the Hermetical Seal at the top. And yet, if one sucked strongly at the open orifice in the longer leg, the water in the shorter would be depressed; and that in the longer ascended at one suck about an Inch and half: Of which the reason is clear in our Hypothesis. For, the Spring of the included Air, together with the weight of the water in the shorter leg, and the pressure of the Atmospherical Air, assisted by the weight of the liquor in the longer leg, counterbalanced one another before the Suction began: But, when afterwards upon Suction the Air in the longer leg came to be dilated and thereby weakened, 'twas rendered unable to resist the undiminish'd pressure of the Air included in the shorter leg, which consequently expanding itself by virtue of its Elasticity, depressed the contiguous water, and made it proportionably rise in the opposite leg, till by the expansion its Spring being more and more weakened, it arrived at an equipollency with the gravitation or pressure of the Atmosphere. Which last clause contains the Reason, why, when the person that sucked had raised the water in the longer leg less than three Inches higher by repeated endeavours to suck, and that without once suffering the water to fall back again, he was not able to elevate the water in the longer, so much as three Inches above its first station. And if in the shorter leg there was but an Inch and a quarter of space left for the Air unfilled by the water, by divers skilfully reiterated acts of Suction he could not raise the liquor in the longer leg above two Inches; because by that time the Air included in the shorter leg had, by expanding itself further and further, proportionably weakened its Spring, till at length it became as rarified, as was the Air in the cavity of the longer leg, and consequently was able to thrust away the water with no more force than the Air in the long leg was able to resist. And by the recited trial it appeared, that the rarefaction usually made of Air by Suction is not near so great, as one would expect, problably because by the dilatation of the Lungs the Air, being still shut up, is but moderately rarified, and the Air in the longer leg can by them be brought to no greater degree of rarity, than that of the Air within the Chest For, whereas the included Air in our Instrument was not expanded, by my estimate, at one suck to above the double of its former dimensions, and by divers successive sucks was expanded but from one Inch and an half to less than four Inches and an half, if the Suction could have been conveniently made with a great and staunch Syringe, the rarefaction of the Air would probably have been far greater; since in our Pneumatick Engine Air may, without heat, and by a kind of Suction, be brought to possess many hundreds of times the space it took up before. From this rarefaction of the Air in both the legs of our Instrument proceeds another Phaenomenon, readily explicable by our Hypothesis. For if, when the water was impelled up as high as the Suction could raise it; the Instrument were taken from th● Suckers mouth, the elevated water would with violence return to its wont station. For, the Air, in both the legs of the Instrument, having by the Suction loft much of the Spring, and so of its power of pressing; when once the orifice of the longer leg was left open, the Atmospherical Air came again to gravitate upon the water in that leg, and the Air, included in the other leg, having its Spring debilitated by the precedent expansion, was not able to hinder the external Air from violently repelling the elevated water, till the included Air was thrust into the space it possessed before the Suction; in which space it had Density and Elasticity enough to resist the pressure, that the external Air exercised against it through the interposed water.  
But our Hypothesis about the Cause of Suction would not need to be solicitously proved to you by other ways, if you had seen what I have sometimes been able to do in our Pneumatick Engin. For, there we found by trials purposely devised, and carefully made, that a good Syringe being so conveyed into our Receiver, that the open orifice of the Pipe or lower part was kept under water, if the Engine were exhausted, though the handle of the Syringe were drawn up, the water would not follow it, which yet it would do if the external Air were let in again. The Reason of which is plain in our Hypothesis. For, the Air, that should have pressed upon the surface of the stagnant water, having been pumped out, there was nothing to impel up the water into the deserted cavity of the Syringe, as there was when the Receiver was filled with Air.   

CHAP. IU.  
BUt because such a conveniency as our Engine, and the apparatus necessary for such Trials are not easily procurable, I shall endeavour to confirm our Hypothesis about Suction by subjoining some Experiments, that may be tried without the help of that Engine, for the making out these three things: 

I. That a Liquor may be raised by Suction, when the pressure of the Air, neither as it has Weight nor Elasticity, is the Cause of the Elevation.  
II. That the weight of the Atmospherical Air is sufficient to raise up Liquors in Suction.  
III. That in some cases Suction will not be made, as, according to the Hypothesis I descent from, it should, although there be a dilatation of the Suckers Thorax, and no danger of a Vacuum though the Liquor should ascend.    
And first, to show, how much the rising of Liquors in Suction depends upon the weight or pressure of the impellent Body, and how little necessity there is, where that pressure is not wanting, that, in the place deserted by the Liquor that is sucked, there should succeed Air or some other visible Body, as the Peripatetic Schools would have it; to ●hew this, I say, I thought on the following Experiments. We took a Glass-pipe fit to have the Torricellian Experiment made with it, but a good deal longer than was necessary for that use: This Pipe being Hermetically sealed at one end, the other end was so bend as to be reflected upwards, and make as it were the shorter leg of the Syphon as parallel as we could to the longer, so that the Tube now was shaped like an inverted Syphon with legs of a very unequal length. This Tube, notwithstanding its inconvenient figure, we made a shift, (for 'tis not easily done) to fill with Mercury, when 'twas in an inclined posture, and then erecting it, the Mercury subsided in the longer leg, as in the Torricellian Experiment, and attained to between two foot and a quarter and two foot and an half above the surface of the Mercury in the shorter leg, which in this Instrument answers to the stagnant Mercury in an ordinary Barometer, from which to distinguish it I have elsewhere called this Syphon, furnished with Mercury, a Travelling Baroscope, because it may be safely carried from place to place. Out of the shorter leg of this Tube we warily took as much Mercury as was thought convenient for what we had further to do, and this we did by such a way as to hinder any Air from getting into the deserted cavity of the longer leg, by which means the Mercurial Cylinder, (estimated as I lately mentioned) retained the same height above the stagnant Mercury in the shorter: The upper and closed part of this Travelling Baroscope you will easily grant to have been free from Common Air, not only for other Reasons that have been given elsewhere, but particularly for this, that, if you gently incline the Instrument, the Quicksilver will ascend to the top of the Tube; which you know it could not do, if the place, formerly deserted by it, were possessed by the Air, which by its Spring would hinder the ascension of the Mercury, (as is easy to be tried.) The Instrument having been thus fitted, I caused one of the bystanders to suck at the shorter leg, whereupon (as I expected) there presently ensued an Ascension of four or five Inches of Mercury in that leg, and a proportionable Subsidence of the Mercury in the longer, and yet in this case the raising of the Mercury cannot be pretended to proceed from the pressure of the Air. For, the weight of the Atmosphere is fenced off by that, which closes the upper end of the longer Tube, and the Spring of the Air has here nothing to do, since, as we have lately shown, the space deserted by the Mercury is not possessed by the included Air, and the pulsion or condensation of the Air, supposed by divers modern Philosophers to be made by the dilatation of the Suckers Chest, and to press upon the surface of the Liquors that are to be sucked up, this, I say, cannot here be pretended in regard the surface of the Liquor in the longer leg is every way fenced from the pressure of the ambient Air. So that it remains, that the Cause, which raised the Quicksilver in the shorter leg upon the newly recited Suction, was the weight of the collaterally superior Quicksilver in the longer leg, which, being (at the beginning of the Suction) equivalent to the weight of the Atmosphere, there is a plain reason, why the stagnant Mercury in the shorter leg should be raised some Inches by Suction; as Mercury stagnant in an open Vessel will be raised by the weight of the Atmosphere, when the Suction is made in the open Air. For, in both cases there is a Pipe, that reaches to the stagnant Mercury, and a competent weight to impel it into that Pipe; when the Air in the cavity of the Pipe has its Spring weakened by the dilatation that accompanied Suction.  
The Second point formerly proposed, which is, That the weight of the Air is sufficient to raise Liquors in Suction; may not be ill proved by Arguments legitimately drawn from the Torricellian Experiment itself, and much more clearly by the first and fifteenth of our Continued Physicomechanical Experiments. And therefore I shall only here take notice of a Phaenomenon, that may be exhibited by the Travelling Baroscope, which, though it be much inferior to the Experiments newly referred to, may be of some use on the present occasion.  
Having then provided an Instrument like the Travelling Baroscope, mentioned under the former Head, but whose legs were not so unequally long, and having in it made the Torricellian Experiment after the manner lately described; we ordered the matter so, that there remained in the shorter leg the length of divers Inches unfilled with stagnant Mercury. Then I caused one, versed in what he was to do, so to raise the Quicksilver by Suction to the open orifice of the shorter leg, that, the orifice being seasonably and dexterously closed, the Mercury continued to fill that leg, as long as we thought fit; and then having put a mark to the surface of the Mercury in the longer leg, we unstopped the orifice of the shorter; whereupon the Mercury, that before filled it, was depressed, till the same Liquor in the longer leg was raised five Inches or more above the mark, and continued at that height. I said, that the Mercury that had been raised by Suction, was depressed, rather than that it subsided, because its own weight could not here make it fall, since a Mercurial Cylinder of five Inches was far from being able to raise so tall a Cylinder of Mercury as made a counterpoise in the longer leg; and therefore the depression we spea●● of, is to be referred to the gravitation of the Atmospherical Air upon the surface of the Mercury in the shorter leg: And I see no cause to doubt but that, if we could have procured an Instrument, into whose shorter leg a Mercurial Cylinder of many Inches higher could have been sucked up, it would by this contrivance have appeared, that the pressure of the Atmosphere would easily impel up a far taller Cylinder of Mercury than it did in our recited Expe●●ment.  
That this is no groundless conjecture may appear probable by the Experiment you will presently meet with. For if the gravity of an incumbent Pillar of the Atmosphere be able to compress a parcel of included Air as much as a Mercurial Cylinder, equivalent in weight to between thirty and five and thirty foot of water, is able to condense it, it cannot well be denied that the same Atmospherical Cylinder may be able by its weight to raise and counterbalance eight or nine and twenty Inches of Quicksilver, or an equivalent pillar of water in Tubes, where the resistance of these two Liquors to be raised and sustained by the Air, depends only upon their own unassisted gravity.  
To confirm our Doctrine of the Gravitation of the Atmosphere upon the surface of the Liquors exposed to it, I will subjoin an Experiment, that I devised to show, that the incumbent Air, in its natural or usual state, would compress other Air not rarified, but in the like natural state, as much as a Cylinder of eight or nine and twenty Inches of Mercury would condense or compress it.  
In order to the making of this, I must put you in mind of what I have shown elsewhere at large, 
See the Author's Defence of the Doctrine touching the Spring and Weight of the Air, against Fr. Linus, chap. 5.  and shall further confirm by one of the Experiments that follows the next; namely, that about twenty nine or thirty Inches of Quicksilver will compress Air, that being in its natural or usual state (as to rarity and density) has been shut up in the shorter leg of our Travelling or Syphon-like Baroscope, into half the room that included Air possessed before. This premised, I pass on to my Experiment, which was this:  
We provided a Travelling Baroscope, wherein the Mercury in the longer leg was kept suspended by the counterpoise of the Air that gravitated on the surface of the Mercury in the shorter leg, which we had so ordered, that it reached not by about two Inches to the top of the shorter leg. Then making a mark at the place where the stagnant Mercury rested, 'twas manifest according to our Hypothesis, that the Air. in the upper part of the shorter leg was in its natural state, or of the same degree of density with the outward Air, with which it freely communicated at the open orifice of the shorter leg; so that this stagnant Air was equally pressed upon by the weight of the collaterally superior Cylinder of Mercury in the longer leg, and the equivalent weight of a directly incumbent pillar of the Atmosphere. Things being in this posture, the upper part of the shorter leg, which had been before purposely drawn out to an almost capillary smallness, was Hermetically sealed, which, though the Instrument was kept erected, was so nimbly done by reason of the slenderness of the Pipe, that the included Air did not appear to be sensibly heated, though for greater caution we stayed a while from proceeding, that, if any rarefaction had been produced in the Air, it might have time to lose it again. This done, we opened the lower end of the longer leg, (which had been so ordered before, that we could easily do it, and without concussion of the Vessel,) by which means the Atmospherical Air, gaining access to the Mercury included in the longer leg, did, as I expected, by its gravitation upon it so compress the Air included in the shorter leg, that, according to the estimate we made with the help of a Ruler, (for by reason of the conical figure of the upper part of the glass we could not take precise measures,) it was thrust into near half the room it took up before, and consequently, according to what I put you lately in mind of, endured a compression like that, which a Mercurial Cylinder of about twenty nine Inches would have given it.  
This Experiment, as to the main of it, was for greater caution made the second time with much the like success; and though it had been more easy to measure the Condensation of the Air, if, instead of drawing out and sealing up the shorter leg of the Instrument, we had contented ourselves to close it some other way; yet we rather chose to employ Hermes' Seal, lest, if any other course had been taken, it might be pretended, that some of the included Air, when it began to be compressed, might escape out at the not perfectly and strongly closed orifice of the leg wherein 'twas imprisoned.  
To make it yet further appear, how much the Ascension of Liquors by Suction depends upon Pressure, rather than upon Nature's imaginary Abhorrence of a Vacuum, or the propagated Pulsion of the Air; I will subjoin an Instance, wherein that presumed Abhorrence cannot be pretended. The Experiment was thus made:  
A Glass-Syphon, like those lately described, with one leg far longer than the other, was Hermetically sealed at the shorter leg, and then by degrees there was put in, at the orifice of the longer leg, as much Quicksilver as by its weight sufficed to compress the Air in the shorter leg into about half the room it possessed before; so that, according to the Peripatetic Doctrine, the Air must be in a state of preternatural Condensation, and that to a far greater degree, than (as I have tried) 'tis usually brought to by Cold, intense enough to freeze water. Then measuring the height of the Quicksilver in the longer Tube above the superficies of that in the shorter, we found it not exceed thirty Inches. Now, if Liquors did rise in Suction ob fugam vacui, there is no reason, why this Quicksilver in the longer part of the Syphon should not easily ascend upon Suction, at least till the Air in the shorter leg had regained its former Dimensions, since it cannot in this place be pretended, that, if the Mercury should ascend, there would be any danger of a Vacuum in the shorter leg of the Tube, in regard that the contiguous included Air is ready at hand to succeed as fast as the Mercury subsides in the shorter leg of the Syphon. Nor can it be pretended, that, to fill the place deserted by the Quicksilver, the included Air must suffer a preternatural rarefaction or descension; since 'tis plain in our case, that on the contrary, as long as the Air continues in the state whereto the weight of the Quicksilver has reduced it, it is kept in a violent state of compression; since in the shorter leg it was in its natural state, when the Mercury, poured into the longer leg, did by its weight thrust it into about half the room it took up before. And yet, having caused several persons, one of them versed in sucking, to suck diver's times as strongly as they could, they were neither of them able, not so much as for a minute of an hour, to raise the Mercury in the longer leg, and make it subside in the shorter for more than about an Inch at most. And yet to show you, that the Experiment was not favourably tried for me, the height of the Mercurial Cylinder in the longer leg above the surface of that in the shorter leg was, when the Suction was tried, an Inch or two shorter than thirty Inches, and the compressed Air in the shorter leg was so far from having been by the exsuction expanded beyond its natural and first dimensions, that it did not, when the contiguous Mercury stood as low as we could make it subside, regain so much as one half of the space it had lost by the precedent Compression, and consequently was in a preternatural state of condensation, when it had been freed from that state as far as Suction would do it. Whence it seems evident, that 'twas not ob fugam vacui, that the Quicksilver did upon Suction ascend one Inch; for, upon the same score it ought to have ascended two, or perhaps more Inches, since there was no danger, that by such an ascension any Vacuum should be produced or left in the shorter leg of the Syphon; whereas, according to our Hypothesis, a clear cause of the Phaenomenon is assignable. For, before the Suction was begun, there was an AEquilibrium or equipollency between the weight of the superior Quicksilver in the longer leg, and a Spring of the compressed Air included in the shorter leg: But when the Experimentor began to suck, his Chest being widened, part of the Air included in the upper part of the longer leg passed into it, and that which remained had by that expansion its pressure so weakened, that the Air in the shorter leg, finding no longer the former resistance, was able by its own Spring to expand itself, and consequently to depress the contiguous Mercury in the same shorter leg, and raise it as much in the longer.  
But here a Hydrostatician, that heedfully marks this Experiment, may discern a difficulty, that may perhaps somewhat perplex him, and seems to overthrow our Explication of the Phaenomenon. For he may object, that if the compressed Air in the shorter leg had a Spring equipollent to the weight of the Mercury in the longer leg, it appears not, why the Mercury should not be sucked up in this Instrument, as well as in the free Air; since, according to me, the pressure of the included Air upon the subjacent Mercury must be equivalent to the weight of the Atmosphere, and yet experience shows, that the weight of the Atmosphere will, upon Suction, raise Quicksilver to the height of several Inches.  
To clear this difficulty, and show, that, though it be considerable, 'tis not at all insuperable, be pleased to consider with me, that I make indeed the Spring of the compressed Air to be equipollent to the Weight of the compressing Mercury, and I have a manifest reason to do it; because, if the Spring of the Air were not equipollent to that Weight, the Mercury must necessarily compress the Air farther, which 'tis granted de facto not to do. But then I consider, that in our case there ought to be a great deal of difference between the operation of the Spring of the included Air and the Weight of the Atmosphere, after Suction has been once begun. For, the Weight of the Atmosphere, that impels up Mercury and other Liquors, when the Suction is made in the open Air, continues still the same, but the force or pressure of the included Air is equal to the counterpressure of the Mercury no longer than the first moment of the Suction; after which, the force of the imprisoned Air still decreases more and more, since this compressed Air, being further and further expanded, must needs have its Spring proportionably weakened; so that it need be no wonder, that the Mercury was not sucked up any more than we have related; for there was nothing to make it ascend to a greater height, than that, at which the debilitated Spring of the (included but) expanded Air was brought to an equipollency with the undiminish'd and indeed somewhat increased weight of the Mercurial Cylinder in the longer leg, and the pressure of the Aerial Cylinder in the same leg, lessened by the action of him that sucked. For whereas, when the orifice of this leg stood open, the Mercury was pressed on by a Cylinder of the Atmospherical Air, equivalent to about thirty Inches of Quicksilver; by the mouth and action of him that sucked the Tube was freed from the external Air, and by the dilatation of his Thorax, the neighbouring Air, that had a free passage through his windpipe to it, was proportionably expanded, and had its Spring and pressure weakened: By which means, the compressed Air in the shorter leg of the Syphon was enabled to impel up the Mercury, till the lately mentioned Equilibrium or equipollency was attained. And I must here take notice, that, as the Quicksilver was raised by Suction but a little way, so the Cylinder that was raised was a very long one; whereas, when Mercury is sucked up in the free Air, it is seldom raised to half that length; though, as I noted before, the impellent cause, which is the weight of the Atmosphere, continued still the same, whereas in our Syphon, when the Mercury was sucked up but an Inch, the compressed Air, possessing double the space it did before, had by this expansion already lost a very considerable part of its former Spring and Pressure.  
I should here conclude this Discourse, but that I remember a Phaenomenon of our Pneumatic Engine, which to divers Learned Men, especially Aristotelians, seemed so much to argue, that Suction is made either by a Fuga Vacui, or some internal Principle, that divers years ago I thought fit to set down another account of it, and lately meeting with that account among other papers, I shall subjoin it just as I found it, by way of Appendix to the foregoing Tract.  
Among the more familiar Phaenomena of the Machina Boyliana, (as they now call it,) none leaves so much scruple in the Minds of some sorts of Men, as this, That, when one's finger is laid close upon the orifice of the little Pipe, by which the Air is wont to pass from the Receiver into the exhausted Cylinder, the pulp of the finger is made to enter a good way into the cavity of the Pipe, which doth not happen without a considerable sense of pain in the lower part of the fing●r. For most of tho● that are strangers to Hydrostatical especially if they be prepossessed wi●● the Opinions generally received bot● in the Peripatetic and other School● persuade themselves, that they f●● the newly mentioned and painful protuberance of the pulp of the finger to be effected not by pressure, as 〈◊〉 would have it, but distinctly by Abstraction.  
To this we are wont to answer That common Air being a Body 〈◊〉 devoid of weight, the Phenomeno● is clearly explicable by the pressure of it: For, when the finger is fir●● laid upon the orifice of the Pipe, no pain nor swelling is produced, because the Air which is in the Pipe presse● as well against that part of the finger which covereth the orifice, as the ambient Air doth against the other parts of the same finger. But when by pumping, the Air in the Pipe, or the most part of it, is made to pass out of the Pipe into the exhausted Cylinder, than there is nothing left in the Pipe, whose pressure can any thing near countervail the undiminish'd pressure of the external Air on the other parts of the finger; and consequently, that Air thrusts the most yielding and fleshy part of the finger, which is the pulp, into that place where its pressure is unresisted, that is, into the cavity of the Pipe, where this forcible intrusion causeth a pain in those tender parts of the finger.  
To give some visible Illustration of what we have been saying, as well as for other purposes, I thought on the following Experiment.  
We took a Glass-pipe of a convenient length, and open at both ends, whose cavity was near about an Inch in Diameter, (such a determinate breadth being convenient, though not necessary:) To one of the ends of this Pipe we caused to be firmly tied on a piece of very fine Bladder, that had been ruffled and oiled, to make it both very limber and unapt to admit water; and care was taken, that the piece of Bladder tied on ●hould be large enough, not only to cover the orifice, but to hang loose somewhat beneath it.  
This done, we put the covered end of the Pipe into a Glass-body (or Cucurbit) purposely made more than ordinarily tall, and the Pipe being held in such manner, as that the end of it reached almost, but not quite, to the bottom of the Glass-body, we caused water to be poured both into this Vessel and into the Pipe (at its upper orifice, which was left open) that the water might ascend equally enough, both without and within the Pipe. And when the Glass-body was full of water, and the same liquor was level to it, or a little higher within the Pipe, the Bladder at the lower orifice was kept plump, because the water within the Pipe did by its weight press as forcibly downwards, as the external water in the large Glass endeavoured to press it inwards and upwards.  
All this being done, we caused part of the water in the Pipe to be ●aken out of it, (which may be done either by putting in and drawing out a piece of Sponge or of Linen, or more expeditiously by sucking up part of the water with a smaller Pipe to be immediately after laid aside;) upon which removal of part of the internal water, that which remained in the Pipe being no longer able, by reason of its want of weight, to press against the inside of the Bladder near as forcibly as it did before, the external water, whose weight was not lessened, pressed the sides and bottom of the Bladder, whereto it was contiguous, into the cavity of the Pipe, and thrusted it up therein so strongly, that the distended Bladder made a kind of either Thimble or Hemisphere within the Pipe. So that here we have a protuberance, like that abovementioned of the finger's effected by Pulsion, not Attraction● and in a case where there can be no just pretence of having ●●course to Nature's Abhorrance of a Vacuum, since, the upper orifice of the Pipe being left wide open, the Air may pass in and out without resistance.  
The like swelling of the Bladder in the Pipe we could procure without taking out any of the internal liquor, by thrusting the Pipe deeper into the water; for then the external liquor, having by reason of its increase of depth a greater pressure on the outside of the Bladder, than the internal liquor had on the inside of it, the Bladder must yield to the stronger pressure, and consequently be impelled up.  
If the Bladder lying loof at the lower end of the Pipe, the upper end were carefully closed with one's thumb, that the upper Air might not get out until the Experimentor thought fit, and if the thus closed Pipe were thrust almost to the bottom of the water, the Bladder would not be protuberant inwards, as formerly; because the included Air by virtue of its Spring, resisted from within the pressure of the external water against the outside of the Bladder: But if the thumb, that stopped the Pipes upper orifice, were removed, the formerly compressed Air having liberty to expand itself, and its elasticity being weakened thereby, the external water would with suddenness and noise enough, not to be unpleasant to the Spectators, drive up the Bladder into the cavity of the Pipe, and keep it there very protuberant.  
To obviate an Objection, that I foresaw might be brought in by persons not well versed in hydrostatics, I caused the Pipe forementioned, or such another, to be so bend near the lower end, as that the orifice of it stood quite on one side, and the parts of the Pipe made an angle as near to a right one as he that blew it could bring it to. This lower orifice being fitted with a Bladder, and the Pipe with its contained liquor being thrust under water after the former manner, the lateral pressure of the water forced the Bladder into the short and horizontal leg, and made it protuberate there, as it had done when the Pipe was strait.  
Lastly, that the Experiment might appear not to be confined to one liquor; instead of Water we put into the unbent Pipe as much red Wine (who●e colour would make it conspicuous) as was requisite to keep the Bladder somewhat swelling outwards, when it was somewhat near the bottom of the water; and than 'twas manifest, that, according as we had foreseen, the superficies of the red liquor in the Pipe was a good deal higher than that of the external water, and if the depth of both liquors were proportionably lessened, the difference of height betwixt the two surfaces would indeed, as it ought to happen, decrease, but still the surface of the wine would be the higher of the two, because being lighter in specie than the common water, the AEquilibrium between the pressures of the two liquors upon the Bladder would not be maintained, unless a greater height of wine compensated its defect of specific gravity. And if the Pipe was thrust deeper into the water, than the Bladder would be made protuberant inwards, as when the Pipe had water in it. By which it appears, that these Phaenomena, without recourse to attraction, may be explicated barely by the Laws of the AEquilibrium of Liquors.  
FINIS.    

NEW EXPERIMENTS About the PRESERVATION OF BODIES IN VACUO BOYLIANO.  
By the Honourable ROBERT boil, Fellow of the Royal Society.  
LONDON, Printed by William Godbid, and are to be Sold by Moses Pitt, at the Angel over against the little North Door of St. Paul's Church. 1674.   

PREFACE.  
MY willingness to make the bulk of the Papers about the Hidden Qualities of the Air less inconsiderable, by things that were of affinity to the Subject, inducing me to tumble over some of my Adversaria, I met among them with divers loose Notes, or short Memorials of some Experiments I made several years ago (and some of a fresher date) about the Preservation of Bodies by excluding the Air, wherefore I was easily persuaded to subjoin these to the Additional Experiments last recited. For it seems not yet clear, by what manifest Quality the Exclusion of the Air should so much contribute to keep from putrefaction variety of Bodies, that are usually found very much disposed to it. And therefore till the Cause of this Preservation be further p●●●●●ated, it may not be altogether impertinent to mention some Experiments relating to it. And though these be only such as come now to hand, and were most of them set down rather as Notes than Relations, yet being faithfully registered, and most of them having been made in Vacuo Boyliano (as they call it) they will problably be New, and so perhaps not altogether useless to Naturalists, who may vary them, and requite me for them, by trying the same Experiments, I made by the Removal of the Air by the bare Exclusion of adventitious Air. For sometimes through hast I did not, and sometimes for want of conveniency I could not, try, whether the same Phaenomena would appear, if the same Bodies were shut up with Air in them, provided they were diligently kept from all commerce with the Air without them.   

NEW EXPERIMENTS ABOUT THE Preservation of BODIES IN VACVO BOYLIANO.  

EXPER. I.  
A Piece of roasted Rabbit, being exactly closed up in an exhausted Receiver the Sixth of November, was two months and some few days after taken out without appearing to be corrupted, or sensibly altered in Colour, Taste, or Smell.   

EXPER. II.  
A small Glass-Receiver, being half filled with pieces of White-bread, (part Crust and part Crumb) was exhausted, and secured the eleventh of March: The Receiver being opened the first of April, part of the Bread was shaken out, and appeared not to have been considerably, if at all sensibly impaired in that time, save that the outside of some pieces of Crumb seemed to be a little, and but a little, less soft and white than before. There appeared no drops or the least Dew on the inside of the Glass. The remaining Bread was again secured soon after,  
The eighteenth of April, the Bread was taken out again, and tasted much as it did the last time, the Crust being also soft, and no drops of water appearing on the inside of the Glass.   

EXPER. III.  
This day (being the ninth of March) I opened a small exhausted and secured Receiver, wherein, ●bout the ninth of December, that is, about three months ago, we had included some Milk: Upon opening an access to the Air, we found the Milk well coloured, and turned partly into a kind of Whey, and partly into a kind of soft Curd. The taste was not offensive, only a little sowrish like Whey, and the smell was not at all stinking, but somewhat like that of sowrish Milk.   

EXPER. IU.  
The Violet-leaves, that were put up, and freed and secured from Air the fifth of March, being this day opened, (April the seventh) appeared not to have changed their shape, or colour, or consistence: For, as for their odour, it could not be well judged of, because he that included them had, for his own ease, contrary to my express direction, ●rush'd many of them together in thrusting them down; and by such a violation of their Texture, it's natural for Violets to lose their fragrancy, and acquire an Earthy smell.   

EXPER. V.  
Having carefully placed some Violets in an exhausted Receiver, of a convenient size and bigness, and secured it from immediate commerce with the external Air; the Seventh month after we looked upon them again, and found they were not putrified or resolved into any mucilaginous substance, but kept their shape entire, some of them retaining their colour, but more of them having so lost it, as to look like white Violets.   

EXPER. VI  
November the fifth, we conveyed into a conveniently shaped Receiver some ounces of Sheeps-blood, taken from an Animal that had been killed that afternoon. And after the exhaustion of the Air, during which, store of bubbles were generated in the Liquor that made it swell notably, the included Blood was kept in a place, (whose warmth we judged equal to that of a digestive Furnace) for twenty days; for one or two of the first of which, the Blood seemed to continue fluid, and of a florid colour, which afterwards degenerated into one that tended more to blackness. On the twenty fifth of November we came to let-in the external, and found it to rush into the Receiver, and the Glass containing the Blood being held in a lightsome place, the most part of the bottom of it seemed to be thinly overlaid with a coagulated substance of a higher colour than that which swum above it, which yet, though it appeared dark and almost blackish in the Glass whilst it was looked on in the bulk, yet, if it was shaken, those parts of it that fell down along the inside of the Glass, appeared of a deep but fair colour. But whilst the Blood continued in the Glass, it was supposed not to stink, since, even when it was poured out, though its smell seemed to me (whose Organs of Smelling are tender) to have I know not what that was offensive, yet to others it seemed to smell but as the Blood of a newly killed Dog.   

EXPER. VII.  
Some Cream being put up and secured the seventeenth of March in an exhausted Receiver, did this day appear to be more thick and almost Butter-like at the top (whose superficies seemed rugged) than otherwhere, and afterwards by being well shaken together in the not inconveniently shaped Glass, was easily enough reduced to Butter, whose Buttermilk, by the judgement of those who were more used to deal in it than I, appeared not differing from ordinary Buttermilk. And I found it had, like that, a grateful sowrness. The Butter was judged to be a little sourer than ordinary, but was not, as they speak, made.  
[In the Entry of this Experiment, Blanks were left for the years; but the Tenor of the words, and Design of the Experiment, and other Circumstances, assure me, that the Cream continued a year in the vessel.]   

EXPER. VIII.  
February the eighteenth we looked again upon three Vials, that had been exhausted and secured the fifteenth of September last, the one of these had in it some slices of roasted Beef, and the other some shivers of white Bread, and the last some thin pieces of Cheese; all which seemed to be free from putrefaction, and looked much as they did when they were first put up: Wherefore we thought not fi● to let the Air into the Receiver, but left them as they were to lengthen the designed Trial.   

EXPER. IX.  
February the eighteenth, there was a fourth Vial, wherein about six months before, viz. August the twelfth, had been enclosed and secured some july-flowers and a Rose; and yet these being kept in the same place with the rest, though they seemed a little moist, retained their shape and colour, especially the Rose, which looked fresh enough to seem to have been gathered but lately.  
N. B. That we observed not in any of these four Receivers any great drops, or so much as Dew in the upper parts, viz. those that were situated above the included matter.   

EXPER. X.  
june the fourth we left some Strawberries in an exhausted Receiver, and coming to look upon them after the beginning of November, we found them to be discoloured, but not altered in shape, nor affording any sign of Corruption by being at all mouldy● Wherefore we thought fit to leave them still in the Receiver for further Trial.   

EXPER. XI.  
May the second, 1669, a piece of roasted Beef, secured September the fifteenth, appeared to be not at all altered: As did likewise a piece of Cheese secured in another Receiver; and some pieces of a French Rose the same day (September the fifteenth) secured in a third.  
N. B. The Flowers sealed up August the twelfth, 1668, being this day looked upon, appeared fresh, and consequently did so after having been kept eight months and an half.   

EXPER. XII.  
There was taken Beer of eight shillings a Barrel, of a year old, near a Pint of which, june the seventeenth, was put into a conveniently shaped Glass, and it was afterwards exhausted and secured from the Air; the most part of the month of August proved extraordinarily hot. Towards the latter end there was at several times great Thunder, which made the Beer in our Cellar, and in most of those of the Neighbourhood, turn sour. The first of September, the Beer was opened, but did not seem to have degenerated into any soureness.   

EXPER. XIII.  
Being desirous to try, whether the Thunder would have such effect upon Ale exactly stopped in Glass-vessels, as it often has on that Liquor in the ordinary wooden Casks; I caused some Ale moderately strong to be put into a conveniently shaped Receiver, and having exhausted the Air and secured a Glass-vessel, 'twas put into a quiet, but not cool, place: Last week, which was about six weeks after the Liquor had been enclosed, there happening some very loud Thunder, and our Beer, though the Cask was kept in a good Cellar, being generally noted to have been turned sour after this Thunder; I stayed yet a day or two longer, that the operation upon our included Liquor might be the more certain and manifest; and then permitting an access to the outward Air, we took out the Ale, and found it to be good drink, and not at all soured.  
Compare this with the Wish made in the Essay of the Great Efficacy of Effluviums, chap. 5. pag. 28. that such an Experiment should be tried.   

EXPER. XIV.  
September the twenty first, 1670, some Blackberries, included in an exhausted Receiver, were opened june the twentieth, 1673, and were found free from all mouldiness and ill sent, only there was found some Liquor that was sour, which being taken out the Berries were secured again.  
[At the same time was another 〈◊〉 of the same Berries exactly closed up i● a Receiver, whence the Air was 〈◊〉 pumped, to try what difference in the Event would appear by this variation. But, coming in October the eleventh, 1673, to look upon the Glass, we found it cracked, and the Fruit all covered over with a thick mould. Nor was this the only Vessel wherein Trials, made to reserve Fruits, without any exhaustion of the Air, miscarried.]  
October the eleventh, 1674, the sam● Berries, being looked upon, appeared to have their colour altered, and much less black than before, but did not appear putrefied by either loss of shape, or by any stinking smell, nor was the least mouldiness observed to be on them, though they had been kept in the same Receiver above four year.  
That Fructus Horarii, especially so tender and juicy ones, should without any additament be preserved from putrefaction so many times longer than otherwise they would have lasted, as 'tis more than would be expected, so it may give hopes, that both odd add useful things of this kind may be this way performed.    

POSTSCRIPT.  
THe foregoing Experiments, as the Memorials themselves declare, were all of them made in Vacu● Boyliano, nor did I intend to set down any other: But meeting among those Memorials with a short account of a couple of Trials made without the help of our Pneumatic Engine, I was induced to annex them, because many may make the like, that will not be able to make such as have been hitherto recited. And these two requiring no peculiarly shaped Vessels, 'tis thought, it may prove of some Oeconomical as well as Physical use, if it be shown by experience, that Liquors Hermetically-sealed the ordinary way in common Bolt-heads may be kept from souring very much beyond their usual time of lasting.  
june the fourteenth we put a convenient quantity of good Ale into a Bolt-head, and sealed it up Hermetically; the next year, on the fifth of july, we broke off the Seal, and found the Liquor very good and without any sensible sourness. The next day it was sealed up again and set by for thirteen months, at which time the neck of the Glass being broken, the Ale was found pretty sour, and therefore the Trial was prosecuted no farther: So that, though this Liquor would not by this way of Preservation be kept from souring so long as the Wine, to be mentioned in the following Experiment, yet even a small quantity of it was preserved good at the least above a year, which is very much longer than Ale is wont to keep from souring.  
june the fourteenth, 1670, in a large Bolt-head was Hermetically sealed up about a Pint, by guess, o● French Claret-wine, which, when we came to look upon, july the fifth, 1671, appeared very clear and high coloured, and had deposited store of feces at the bottom of the Glass, but fastened no Tartar that we could perceive to the sides. Upon the breaking of the sealed end of the Glass, the Bystanders thought, that there was an eruption of included Air or steams, and, above the surface of the Wine, there appeared, to a pretty height, a certain white smoke almost like a mist, and then gradually vanished: The Wine continued well-tasted, and was a little rough upon the tongue, but not at all sour.  
The Bolt-head was sealed up again july the sixth 1671, and so set by till August the fifth 1672, at which time it was opened again, and then the Wine did still taste very well.  
june the twenty sixth 1673, the Bolt-head with the same Claret-wine was opened, and was found very good, and was sealed up again.  
October the eleventh 1674, the same Claret-wine was opened again, and appeared of a good colour, not sour, but seemed somewhat less spirituous than other good Claret-wine, perhaps because of the Cold weather.  
This, and the foregoing Trial about the Preservation of Ale, were made in Mr. Oldenburg's House and Presence.  
FINIS.