Certain physiological essays and other tracts written at distant times, and on several occasions by the honourable Robert Boyle ; wherein some of the tracts are enlarged by experiments and the work is increased by the addition of a discourse about the absolute rest in bodies.

THE HISTORY OF Fluidity and Firmnesse. (Book 2)

The Second Part. Of FIRMNESSE. (Book 2)

IT is sufficiently known that the Chymists ascribe the Firmness and Hardness of Bodies to Salt, and teach that the Saline Ingredient of them is the Principle of Coagulation in them, and the cause of their Compactness and Solidity. But though this opinion of the Chymists be embra'cd by so many mo∣dern Philosophers and Physitians, that some may think it superfluous to make enquiry after other Causes, yet o∣thers (to whom the Explications of Chymists seem not al∣ways so much as Intelligible) will upon the very account of the Receivedness of the propos'd Opinion, think it ra∣ther worthy to be examined than to be acquiesc'd in. How∣ever, without making it our business, either to side with, or oppose any Sect of Naturalists, we will apply our selves a while to consider the thing it self in prosecution of the Design already begun. And having in the fore-going

Part of our little History taken a general view of Fluidi∣ty; we will now proceed to try what Light it will af∣ford us to discover the nature of Firmness or Compact∣ness.

And since fluidness and stability being contrary quali∣ties, are to be apprehended under contrary notions, we may conceive that the firmness or stability of a body con∣sists principally in this, that the particles that compose it, besides that they are most commonly somewhat Gross, ei∣ther do so rest or are so intangled between themselves, that there is among them a mutual cohesion whereby they are rendred unapt to flow or diffuse themselves every way, and consequently to be, without violence, bounded and figur'd by other surfaces than those which their connexion makes themselves constitute.

In this rude Description of Firmness we have intimated Three principal causes of it, namely the Grossness, the quiet Contact, and the Implication of the component parts.

The first is Grossness of Parts, of which we have in effect almost sufficiently discours'd already: for since treat∣ing of Fluidity, we manifested at large how conducive smalness of Parts was to that Quality; 'tis easie to deduce that Grossness of parts in a Body must commonly be a great disposition to its being Firm. And bigger Corpus∣cles being caeteris paribus more difficult than lesser to be put into motion, when they are on••e at rest, it is obvious that a Body consisting of such Particles is less dispos'd to become fluid, and consequently more apt to continue firm, than if its component parts were smaller, and there∣by more easie to be displac'd. But when I speak of the Grossness of Corpuscles, I pretend not to determine whether or no Body or Matter be so perpetually divisible, that there is no assignable portion of matter so minute that it may not at least Mentally (to borrow a School term) be

further divided into still lesser and lesser parts: For allow∣ing this indefinite Divisibility of corporeal substance, 'tis plain that it may in some sense be averr'd, that there are no firm Bodies whose Parts are not extreamly minute. But I understand by the gross parts I here speak of, such Cor∣puscles as actually convening to constitute a Body, are scarce dissipable or divisible into lesser by the Agitation of the ambient Air or Aether, or by the other causes of the Fluidity of Bodies.

It is also to be noted, that when I spake of the fitness of grosser Corpuscles to make a firm Body, I added, Cae∣teris paribus, because it may happen that the breaking of the small parts of a Body into minute Particles may make them but the fitter to contribute to the Firmness of the Body they belong to: For the parts of the divided Cor∣puscles may by their comminution acquire a new, and perhaps a more irregular shape than before, upon whose account they may be more dispos'd to be entangled among the neighbouring Particles, or may be better fitted to get into and fill the pores of some kind of Bodies. And in in such little Particles, not only the minuteness may make them lie closer together, and consequently the better ex∣clude the Air: but the greatness of the surface in propor∣tion to the bulk of the matter may perhaps in some Cases occasion a fuller contact, and so facilitate the constitution of a very firm Body, in case these minute parts (whose intervals (if they intercept any) need not be other than very small) shall be placed and disposed to the best advan∣tage for a full contact of one another. But as I said a while before, from what we have already delivered (con∣cerning the size of parts, when we treated of Fluidity) it may easily be understood how much the magnitude of them may conduce to Firmness; and therefore we will presently pass on to the mention of the two other things to be considered in reference to consistent Bodies. Where∣of

of the one is the bare Rest of the small and contiguous parts that make up the firm Body; and the other the in∣tricate Texture of such parts in the body they make up. And either of these two seems alone sufficient to render a body stable: though Nature do perhaps oftentimes make some (though not equal) use of both, to fasten the parts of the same body more firmly together.

Of the former of these Causes, I am inform'd that the justly famous Monsi••ur Des Cartes has also taken notice, but without adding proof from Experiments, or Observa∣tions. But it seems to have been either over-look'd, or, (as incongruous to their Hypothesis of the innate motion of Atoms) rejected by the old Atomists, and by Lucretius, who takes notice (that I remember) only of the latter: for though they did of old make mention of the sudden divulsion of two flat and solid Bodies, yet they employ that Observation but to prove a Vacuum, (without other∣wise taking notice, that I have met with, of those things that are most material in such Observations to our present purpose, and without deducing thence what we shall en∣deavour to do in order to the explication of the causes of Firmness.) Upon what account then soever the Atomists have omitted to reckon for a cause of Firmness that which we have newly been speaking of; yet (as we ob∣served above) If two bodies be once at rest against one another, it seems consonant to the Catholick Laws of Na∣ture, that they should continue in that state of rest, till some force capable to over-power their resistance puts them out of it. And whatever may be said of the un∣loosable mobility of Atoms strictly so taken, yet that di∣verse parts of Matter may compose bodies that need no other Cement to unite them than the juxta-position which we here presuppose, and the resting together of their parts, whereby the Air and other fluid Bodies that might dissociate them are excluded, I have been inclined to

think by what I have observed in grinding of Glasses: for sometimes the convex surface of one body being ground upon the concave surface of another, the two surfaces will happen to be so closely and exactly fitted to one ano∣ther, (their immediate contact in all their parts, or at least in innumerable of them, hindering the intercurrence of the Air) that a man is not able without breaking one or both of them to pull them directly asunder; but if you will sever them, you must be fain to make one of them to slip along the surface of the other: which makes the Glass-Grinders often complain of the trouble they meet with in separating such bodies. Nay, if you lay two flat Glasses ground very true and well polished upon one ano∣ther, so that their surfaces may almost every where touch each other, (to which it will be requisite to rub them a little one upon another, for the better exclusion of the Air) you may by lifting up the uppermost, lift up the lowermost (though perhaps, as we have often try'd, two or three times bigger) with it, as if the two Plates of Glass made but one body. Nay, we have divers times taken up four or five pieces of Glass at once, laid and prest thus one upon another, and might perchance have taken up a greater number, if we had had more of them at hand. And tryal has also informed us, that if you hold a Looking-Glass very level with the unfoliated side downward, and rub a little against it a piece of other very flat and very smooth Glass, you may easily by that way only, fasten them to one another; so that the lowermost Glass, though large, will hang between the uppermost and the ground, to the wonder of those that behold it, and can discern nor imagine nothing capable to keep it from falling: and by the same way (as we shall recite a∣non) we have often made one considerably thick piece of Marble take and hold up another, having purposely caused their flat surfaces to be carefully ground and po∣lished,

without which the Experiment will not succeed. Nor is it requisite that the glasses be flat to make them ad∣here very closely together, provided their immediate con∣tact be made according to a large surface: for to what we have already mention'd concerning the cohering of con∣vex and concave Bodies, we may adde, that having pur∣posely appli'd a long glass-stopple of an almost conical fi∣gure, and well ground, to the mouth of a thick quart Bottle, whose neck was made long and of a figure conve∣nient to receive the stopple, and ground within fit for it, we found that these two glass bodies touching one ano∣ther in a multitude of parts, did adhere together so close∣ly, that when the stopple was carefully put in, we could easily, and divers times one after another, lift up the bot∣tle, though there was by our guess above a pound of Li∣quor in it. Unless we suppose, without much probabili∣ty, that because 'tis found, that moving them to and fro upon one another, and pressing down the stopple, pro∣motes their sticking, their adhesion may be in part ascrib'd either to some Elastical motion in the parts of the pressed glass, or to the exquisite adaptation of the almost number∣less, though very small, asperities of the one, to the as numerous little cavities of the other; whereby the sur∣faces do lock in with one another, or are as it were clasp'd together. For as polish'd as the surfaces may appear to sense, we must not deny that there may be such inequali∣ties in them, since being wont to be polish'd with Putty or some such powder, or heap of grating and irregularly shap'd Corpuscles, they must needs make store of little furrows, and ridges, and other Asperities on them. But to insist on these Conjectures were to digress.

Yet here we must not decline taking notice, that, at least here below, the sticking together of such bodies as are of sensible Bulk, and whose smooth surfaces immedi∣ately touch one another, may possibly not so much pro∣ceed

from this, that their parts, as we formerly observ'd, are at rest among themselves, and by their immediate contact do make up as it were but one body; as from the pressure of the Atmosphere, proceeding partly from the weight of the ambient Air, (mixt with the Effluviums of the terrestri∣al Globe) and partly from a kind of Spring, by vertue of which the Air continually presses upon the bodies contigu∣ous to it, though through accustomance & negligence, & perhaps some other causes not here to be insisted on, we neither feel it in our own bodies, nor take notice of it in o∣thers. Now this pressure of the Air every way being suppos'd, I think the adhering of the smooth bodies we speak of (for we suppose them far greater than the parti∣cles of the Air) to one another may probably enough be ascrib'd to this, That when, for instance, the smooth surfaces of two pieces of Glass do so exquisitely touch one another, that none of the ambient Air is ei••her intercept∣ed or admitted between them, then the undermost glass will suffer no pressure on that side which touches the up∣permost; the parts of the uppermost glass having no sen∣sible spring in them (so that they can only Resist, but not Repell the other:) but that side of the undermost Glass which is expos'd to the Air will be press'd upon thereby; and there being, as we said, no Elastical pressure on the other side of the glass to balance this, it is not to be won∣der'd at that the inferiour glass should not fall off from the other, in regard the weight that would carry it down∣wards is much too small to overcome that force of the Air that thrusts it against the uppermost glass: As if one should with his hand thrust a plate of Iron broad-wise a∣gainst the flat cieling of his Chamber, the Iron would not fall as long as the force of the hand perseveres to press a∣gainst it. Nor is it material, that in our Case the pres∣sure of the Atmosphere is suppos'd to force the lowermost glass upwards: For if we suppose the Air to consist of in∣numerable

little springs (as it were) bearing upon and supporting one another, and whereof the lowermost are bent by the Weight of all that are incumbent on them, it will be easie to conceive that neer the surface of the Earth, (about which the Air must diffuse it self by reason of the Gravity of its small parts, and the Resistance of the Earth against their Descent) it may press almost equally every way, and by a kind of Recoyl (though not properly so call'd) from the Terrestrial Globe upwards, may strong∣ly press any body upon which it can bear, against any o∣ther which has no such Elastical power to repel from it a body so press'd against it.

This Difficulty being thus dispatch'd, we shall proceed by two or three particulars to confirm our Conjecture at the Cause why smooth Bodies stick ••ogether upon bare juxta-position or contact. And firs•• •• observe, that if a piece of flat glass be, as we formerl•• mention'd, append∣ed to a Looking-glass held with the unfoliated side down∣wards, parallel to the Horizon, though the adhering glass will not drop down, yet it will v••ry easily be mov'd any way along the level surface; and if by inclining the Look∣ing-glass any way, you deprive it of its former Level, the smaller glass will easily slide downwards upon the sur∣face of the greater. Of which the Reason seems to be, partly that the Gravity as such of the lower glass does not considerably resist the horizontal motion of it, but only the motion upwards, whereby it must recede from the Centre of heavy Bodies, as might, if need were, be pro∣bably deduc'd from divers Instances obvious enough; and partly, or rather chiefly, that to the edges of the glass the Ambient Air is contiguous as well on the one side as on the other, and so the pressure of the Air being equal on every part of the edges, the gravity of the smaller glass is not hinder'd by the Air (which can as fast succeed on one side, as 'tis displaced on the other) from making it

slide down the shelving surface of the greater Glass, where∣as of the broad and flat sides of the lowermost glass the one is, as we said, press'd by the spring of the Air, whilst the other suffers no such pressure from the Looking-glass, to which it was apply'd. And so, if you take a small o∣pen-mouth'd glass, and plunge it into a Vessel full of Quick-silver with the mouth upward, that the Quick-sil∣ver may fill it without leaving any Air in it, and if then, whilst it is under the Quick-silver, you turn the mouth downwards, and so keeping it upright, lift it up till the mouth be almost come to the top of the Mercury; you shall perceive that the glass will remain almost full of Quick-silver in the Vessel: And this will continue so, though you incline the glass this way or that way, provi∣ded you keep the mouth of it within the Mercury. And this Experiment, though more noble when try'd with Quick-silver, will succeed also when tryed, as it may more easily be, with water. Of which the Reason seems to be, that the glass hinders the Quick-silver in it from the pressure of the incumbent air, whereas the Quick∣silver in the Vessel being expos'd to it, must by it necessa∣rily be forced up against the surface of the inverted bot∣tom of the glass, where it meets no Elastical power to re∣pell it downwards. For, that it is not Natures Abhor∣rency of a Vacuum, that keeps the Quick-silver from descending till some air can come to succeed in its room, the famous Experiment invented by Torricellius, and found true by many others, and our selves, touching the descent of Quick-silver in any Tube of above two foot and a half long, seems clearly to evince. And to confirm what we have said, and shew withall, that it is not so much the Contact of Bodies according to a large surface, as that Contact is considered in it self, as by reason of its being ordinarily requisite to the exclusion of Air, that at least here below keeps bodies from falling asunder; I shall

relate, that having by a certain Artifice out of a large glass (with a narrow mouth) caus'd a certain quantity of air to be suck'd, we found that by immediately applying a Book (which then chanc'd to lie at hand) to the Ori∣fice of the Vessel, the Book was readily lifted up and su∣stein'd in the air as long as we pleas'd, though the surface of the suspended Body could be touch'd, as is evident, but by the Ring which incircl'd the Orifice of the Vessel, and though the weight taken up (besides that it was in∣conveniently shap'd for such a trial, which would proba∣bly have succeeded as well with a much greater weight, if we had had one fitly shap'd at hand) exceeded twenty Ounces * 1.1. Of which event the Cause seems plainly to be this, that by reason of the Exsuction of some air out of the glass, the Elastical power of the remaining Air was very much debilitated in comparison of the unweaken'd Pressure of the External air, which being able to press the Book against the Orifice of the Vessel with greater strength than the internal air can resist, thereby it comes to pass, that the whole Orifice of the Vessel, though there be but part of it of solid body, does yet on this oc∣casion perform in some measure the part of an entire sur∣face exactly smooth.

It may be consider'd also (to adde that upon the by) whether upon the Principle lately explicated may not in some measure depend the solidity of glass. For though its parts seem very little or not at all branched or inter∣woven one within another, and appear very smooth and slippery, yet since the fire that brought them to fusion, and consequently to be fluid, may well be supposd to have sub-divided and reduc'd them into very small Parti∣cles, and to have thereby assisted them to exclude the air from b••twixt them, it may seem that it needs not much

be wonder'd at, if the immediate contact of such small and smooth Corpuscles suffice to make them hold toge∣ther; for that their union is strict enough to keep out the air, may appear from this, that those that blow glasses, and those that distill in them, find not the air can traverse the pores even of heated glass; and as for any more subtil matter, we see by the free passage of Light and Heat, or, to speak more warily, of magnetical Effluvia through glass, without injuring its texture, that such matter but moderately mov'd will not hinder the little solid parts from cleaving together. And on this occasion it might be consider'd, how much the juxta-position of their Cor∣puscles crowded together by fusion may contribute to the consistence and brittleness of Salt-Petre, and diverse other bodies, which may from an incoherent powder be readily turn'd into one Mass; as also how far the sticking together (for I speak not of the figures compos'd by them) of the small parts of hanging drops of water, and such other Liquors as are not thought to consist of Corpuscles hooked or branch'd, may be ascrib'd to the contact of their small parts, and the exclusion of air. These, I say, and some other such things might be here consider'd, but that we are forbidden to examine them particularly, and especially what has been represented touching the soli∣dity of glass, (which we suspect another cause may have a great Interest in) by our haste, which calls us to the remaining part of our Discourse.

Though then it be hence (to omit other proofs else∣where mention'd) sufficiently manifest, that the Air has a spring, and that a strong one, yet there appears no great necessity of having recourse to it for the giving an Ac∣count why the two smooth glasses above mention'd were able to adhere so closely to each other: For a probable Reason of the same Phaenomenon may be rende••'d by the pressure of the Air consider'd as a weight. And fi••st,

we must recall to mind what we (a little above) said of the Recoyling, (or Rebounding of the Pressure) of a Cylinder of Air from the Earth, to the suspended piece of glass, proceeding from this, that the fluid Air, which is not without some Gravity, being hinder'd by the resisting sur∣face of the terrestrial Globe to fall lower, must diffuse it self, and consequently press as well upwards as any other way. Next, we may consider, that when the surfaces of two flat Bodies of any notable (and for example of equal) breadth do immediately touch each other, and lye both of them level with the Horizon, and one of them directly over the other; in this case, I say, since the Air cannot move in an instant from the edges to the middle of the two surfaces that lye upon each other, the lowermost cannot be drawn away downwards in a perpendicular line from the uppermost, but that by reason of the stiff∣ness and contact of the two Bodies, it must necessarily happen that at the instant of their separation, should it be effected, the lowermost glass will be press'd upon by the whole (Crooked) Pillar of Air, suppos'd to reach from the top of the Atmosphere, and to have for Basis the super∣ficies of the undermost glass. For at that instant, the Air having not time to get in between the two glasses, there is nothing between them during that instant to resist the pressure of that Air which bears against the lower super∣ficies of that undermost glass, and consequently such a revulsion of the lower glass cannot be effected but by a weight or force capable to surmount the power of the weight of the abovemention'd Cylinder of the Atmo∣sphere; and this, as I said, because that by reason of the sudden separation, the upper surface of the glass has not any air contiguous to it, which, were it there, would (according to the nature of Fluid and springy Bodies) press as much against the upper surface of the glass, as the Pillar of the Atmosphere against the lower, and conse∣quently

sustain that Endeavour of the Air against the lower side of the glass, which in our propos'd case must be surmounted by the weight or force employ'd to draw down the lower glass. And hence we may understand (to adde that upon the by) That it is not necessary that the contiguous surfaces of the two flat glasses we have been treating of, be parallel'd to the Horizon: For if you should hold them perpendicular to it, their divul∣sion would not cease to be difficult, provided it were attempted to be made by suddenly pulling one of the broad surfaces from the other in a level line, and not by making one of the surfaces slide upon the other; for in the former case, the separation of the contiguous Bodies will be hinder'd by the weight or pressure of the lateral Air (if I may so speak) that bears against the broad sides of the glasses contiguous to it. But whereas in these ca∣ses we suppose the superficies of the two glasses to be so exactly flat and smooth, that no Air at all can come be∣tween them; Experience has inform'd us, that it is ex∣treamly difficult, if at all possible, to procure from our ordinary Tradesmen either Glasses or Marbles, so much as approaching such an Exquisiteness: For we could very hardly get either experienc'd Stone-cutters, or Persons skill'd at grinding of glasses, to make us a pair of round Marbles, though of an inch or two only in Diameter, that would for so much as two or three minutes hold up one another in the Air by contact, though they would easily enough take up each other, if the uppermost were drawn up nimbly, before the Air could have leisure to insinuate it self betwixt them.

But this notwithstanding, we endeavour'd by the fol∣lowing Expedient, not only to manifest that the Power or Pressure of the Air is in these Experiments very great, but also to make some Estimate (though but an imper∣fect one) how great that Power is.

Having then provided a pair of Marbles of an inch and half in Diameter, and as flat and smooth as we could get, and having consider'd, that as 'twas the getting in of the Air between them that (for the reason above declar'd) hinder'd them from sticking strongly together; so the Access afforded to the Air was for the most part due to that scarcely evitable roughness or inequality of their sur∣faces that remain'd in spight of the Polish: considering these things, I say, we suppos'd that the intrusion of the Air might be for some while prevented by wetting the surfaces to be joyn'd with pure Spirit of Wine; and that yet this Liquor, that seems the freest that we know of from tenacity, would not otherwise than by keeping out the air prove a Cement to fasten the stones together. But because the easie separation of such smooth Bodies as ad∣here but by contact does in great part (as we formerly noted) proceed from this, That whereas it is very diffi∣cult to hold such Bodies exactly level for any considerable space of time, and yet the least Inclination any way gives the lower Body opportunity to slide off; because of this, I say, we resolv'd in the first place to see what could be done by fastening to the upper Marble certain Wires and a Button, in such manner as that the lower Marble, when it was joyn'd, might freely fall directly down, but no•• slip much aside, being hinder'd by the Wire. And in pursuit of this we found, that not only the dry Marbles could be made to take up and hold up one another, but that once by drawing up the upper Marble nimbly, we could take up (but not keep up for any time) together with the lower Marble, a Scale, and in it a pound weight of 16 Ounces Troy.

After this we moisten'd the surfaces of the Marbles with such pure Alkalizate Spirit of Wine as we elsewhere teach to make, which was so thin and subtil, that not on∣ly we burn'd some of it before we would employ it

about this Experiment in a Silver Spoon, without leaving so much as any sign of Phlegm behind; but it would (in the open air) almost in a moment fly away from the sur∣face of the Marble anointed with it, and leave it dry and glossy. The Marbles being skilfully wetted, and kept by the above-mention'd wires from slipping aside, we cast into a Scale fasten'd to the lower of them diverse weights at several times, and by nimbly pulling up the higher stone, try'd many times how much we could draw up with the lower, and did sometimes take up above an hun∣dred Ounces, and once an hundred thirty two Ounces Troy, besides the Scale that contain'd them, and the Marble it self, the Diameter of whose smooth surface was by measure but about an inch and two thirds.

But here I must take notice, both in relation to this and the following Experiments to be set down concerning smooth Marbles, that we never yet found any sort of Ex∣periments, wherein such slight variations of circumstan∣ces could so much defeat our Endeavours; which we therefore mention, that in case such Experiments be try'd again, it may be thought the less strange, if others be not able to do as much at the first and second, or perhaps the tenth or twentieth tryal, as we did after much Practice had made us expert in this nice Experiment, and suggested to us divers facilitating Circumstances, which could not here in few words be particularly set down.

And now, because we perceiv'd that the Spirit of Wine was too fugitive and subtil a Liquor for our purpose, we suppos'd that Oyl, as it would better fill up the little ca∣vities of the Stones, so it would more exactly keep ••ut the air, and less easily v••nish into it. And accordingly, having moisten'd the surfaces with a due Proportion of good express'd Oyl of sweet Almonds, and having care∣fully observ'd the other requisite Circumstances, we to••k up some drams above four hundred Ounces Troy hang∣ing at the lower Marble.

And that you may not suspect that it was by glewing the Marbles together, that the Oyl did enable them to make so much greater resistance against separation than the Spirit of Wine did; I shall adde, That in case the flat surfaces of the joyn'd Stones were held not parallel, but perpendicular to the Horizon, that so the air might (as we formerly also observ'd) immediately succeed as the looser Marble should slide off, the weight of some Ounces was now and then requisite to draw down the Marbles when they had nothing but Spirit of Wine between them, whereas they would easily enough slide off from one ano∣ther when they were cemented together with Oyl: per∣haps because that the Spirit of Wine by reason of the smallness and penetrancy of its parts, and because of its fugitive nature, did not so well fill up the little pores and furrows of the surfaces of the Marbles; whereby the little protuberances getting into those little cavities, might more resist the sliding of the Marbles upon one anothers surfaces, whose texture is better fitted to make ••heir sur∣faces smooth and slippery.

And to shew that the resistance of such contiguous Mar∣bles to a violent separation is greater in those which being broader are press'd against or resisted by a proportionably bigger (though not a longer) Pillar of the Atmosphere; We caused two Marbles to be made, whose Diameter was three inches or a very little more: and having after the abovemention'd manner employ'd Spirit of Wine to keep out the air from between them, we did after some tryals, with the uppermost of them take up the lowermost, and with it four hundred sixty eight, or four hundred and se∣venty Ounces. But making use of Oyl of Almonds in∣stead of Spirit of Wine, we did with our own hands draw up twice, one time after another, with the undermost Stone, a much greater weight, namely, eighty four pound or 1344 Ounces (Troy weight) notwithstanding which

weight we manifestly perceiv'd the Marble at which it hung to stick strongly to the other.

And here again we will take notice, that the interpos'd Oyl was so far from being able as a Cement, rather than by keeping out the air, to make these Marbles stick so close together, that, whereas Bodies glew'd or cemented together are wont to make an almost equal resistance to their being separated, in what Posture soever you place them, I made our Marbles, even when we try'd this last Experiment, very freely slide upon one another, by impel∣ling the upppermost to the right hand or to the left, with my Finger or my Thumb: (whereof the reason is inti∣mated above, where we mention'd almost the like case in Glasses) and having sometime before taken up a weight which we conjectur'd to be not much inferiour to that last named, we presently for tryal sake held the Marbles with their edges downwards, and found that those that in an Horizontal Position could not be drawn asunder by so great a weight, did in another posture presently fall asunder by their own weight, which made one readily slide off from the other to the ground. Now although we have confess'd, that this way of measuring the force of the Air is not Accurate; yet we hope it will not be thought Useless, since (not to mention that by thus break∣ing the Ice, we may make way for the happier Enquiries of others) it not only shows us that this pressing or sustaining force of the air, as unheeded as it is wont to be, is very Great, but it may also assist us to conjecture how Great it is, which though we cannot hereby determine precisely and with certainty, yet we may estimate it with much less uncertainty than otherwise we could.

I know that the Peripateticks, and the generality of the School Philosophers, will confidently ascribe the sticking of the Marbles, not to the cause we have assign'd, but to Natures Abhorrency and fear of a Vacuum. But not

to engage our selves now in a Disquisition that when we discours'd of Fluidity we did (for the Reasons there ex∣press'd) decline to meddle with; We will, without dis∣puting whether or no Nature either can at all admit, or do abhorre a Vacuum, content our selves to confirm the Ex∣plication given of this Phaenomenon by these two Con∣siderations. The one, That if Nature did so violently oppose a Vacuum as is pretended, it is not likely that any force whatsoever that we could employ would be capa∣ble to produce one; whereas in our case we find, that a little more weight added to the lower of the Marbles, is able to surmount their Reluctancy to separation, not∣withstanding the suppos'd danger of thereby introducing a Vacuum. And my next Consideration is, that (accord∣ing to what we have hitherto deliver'd) without having recourse to any such disputable Principle, a fair account may be given of the propos'd Phaenomenon, by the pres∣sure or weight of the Air. And that what we have said concerning the latter of these may be entertain'd with the less difficulty, let us suppose, that when the Marbles stick well together, the lowermost of them, or the appendant weight were fasten'd to the ground: For in this case there appears no reason to believe that their power to resist se∣paration would be less than it was before. And yet it seems evident, that the uppermost Marble would not be perpendicularly pull'd up but by such a force as were at least (I say at least) able to lift up a weight equal to that of the last mention'd Marble, and of a Pillar of Air ha∣ving the Stone for its Base, and reaching to the top of the Atmosphere; since at the instant of Revulsion, before the Air can get in, and spread it self between the Stones, there is not for ought appears any such Body under the upper Marble, as can help the hand to sustain the weight both of that Marble and the incumbent Cylinder of the Atmosphere, which then gravitates upon it, and conse∣quently

upon the hand; bec••use there is no Air, nor other equivalent Body underneath it, to sustain its part of the weight, as the lower Air is wont to do in reference to the heavy Bodies that lean on it, and to the weight of the incumbent Air. And therefore we need not much marvel, if when only a less weight than that of the foremention'd Pillar of the Atmosphere hangs at the lower Marble, it should be capable of being drawn up by the uppermost, rather than suffer a divulsion from it. As we see that when two Bodies being fasten'd together, are endeavour'd to be drawn asunder by forces or weights not able to separate them, they will usually both of them move that way, to∣wards which either of them is the most strongly drawn. On which occasion, I remember what I have sometimes observ'd in one of the wayes of trying the strength of Load-stones: For if the Load-stone be able to take up more than its own weight, you may as well lift up the Load-stone by a Knife, as the Knife by the Load-stone. And though one accustom'd to judge only by his Eyes, would have imagin'd, that when I held the great weights formerly mention'd suspended in the Air, there was no strong endeavour to pull up the upper Marble from the lower, because my hand being for a while held steddy, seem'd to be at rest; yet he will easily be invited to sus∣pect that in such a thought there may be a great mistake, who shall consider, that neither did the weight sensibly appear to pull the lower Marble downwards, though my hand assur'd me that the weight had not lost its Gravita∣tion. And if I shall adde, that once, when the weight after having been lifted up into the Air, was casually so loosen'd from the upper Marble, as suddenly to drop down, my hand, unawares to me, was by the force of that Endeavour it just before employ'd to sustain the fallen weight, carried up with such violence, that I very sensi∣bly bruis'd it by the stroak it gave against the face of a By∣stander,

who chanc'd out of curiosity to hold his Head over the Marbles.

And here it will not be impertinent to bring in an Ex∣periment that I once devis'd, not only for other uses, but to illustrate the subject we have been hitherto treating of. The Tryal I lately found registred among my Adversaria, in these Termes. A Brass Valve of about an Inch Diame∣ter was with Cement well fastned to the shorter Leg (which was but of very few Inches in Length) of a long Glass Syphon left open at the end of the other Leg. This Valve being let down to the Bottom of a tall Glass Body full of water, so that 'twas (if I much mis-remember not) between a Foot and half a yard beneath the surface of the water, when there was let in as much water into the Pipe, as reach'd in that as high as the surface of the External Water in the Tall Cucurbite: Then about an Ounce weight was put into the opposite Scale of a Ballance, to the neighbouring Scale whereof one end of a string was tyed, whose other end was fastned to the said Valve, whose parts would be thereby drawn asunder. But when the water was empty'd out of the Pipe, and the Valve was let down to the former depth, there was requisite about 5 Ounces, that is 4 Ounces more than formerly, to disjoin the parts of the Valve, and let the water get in between: And when (the Syphon being freed from water) the Valve was listed higher and higher, together with the Pipe, there needed less and less weight to make a Disjunction; two Ounces of Additional weight (to the one Ounce requisite to counterpoize the Cover of the Valve it self) on the water sufficing to lift up the Cover, when the Valve was held about half way, between its Lower station, and the Top of the water; a single Ounce sufficing afterwards, and half an Ounce of Additional weight proving enough to disjoin the parts when the Valve was held but a little beneath the surface of the Liquor.

This relation of an Experiment which I afterwards show'd to many Virtuosi, will perhaps seem somewhat dark to you without a Scheme; but if you consider it attentively enough to apprehend it throughly, I presume it will show you, that whether or no there be upon any other score a repugnancy to the separation of smooth Bodies join'd by immediate contact; yet certainly there may be a great Repugnancy upon the bare Account of the Gravity of the medium, wherein the Divulsion is at∣tempted. For in our case the Fuga Vacui, if there be any, ought to resist the separation of the Parts of a Valve still kept under water, as much near the Top of the water, as at the Bottom. And therefore the great difference found in that resistance at those different places, may be attribu∣ted to the Pressure of the Ambient water, that thrust them together. And though it be true that Air is an Exceeding Light Body in comparison of water; yet in divers Tryals I have found the Disproportion in Gravity of those two Fluids not to exceed that of a 1000. to 1. So that considering how many miles, not to say scores of miles, the Air may reach upwards, there seems no absurdity at all to suppose that the bare Pressure of it against the Marbles formerly mention'd, may keep them as coherent as we found them to be.

But since this I have been able to make an Experiment, that does sufficiently confirm the former Doctrine. For having suspended the two coherent Marbles in a Capacious Glass, whence by a certain con∣trivance, the Air could little by little be drawn out, we found as we expected, that whilst there remain'd any considerable quantity of Air in the Glass, the lower Marble continued to stick to the other, the Pressure of the remaining Air, though but weak, being yet suffi∣cient for the sustentation of the lower Marble, which it was not after the Air was further withdrawn. And if when the Disjunction was made, the upper Marble were by another contrivance let down upon the lower, so as to touch it as before; though whilst the External Air was kept out of the Glass, the upper Marble might easily be rais'd without taking up the lower with it; yet when the outward Air was let in, the Marbles were press'd together, and became again strongly coherent.

But it is now high time to look back to that part of our Discourse, which the consideration of our Marbles has so long intic'd us from directly prosecuting. Although then it may from the past Discourse be conceiv'd, that in Bo∣dies of sensible bulk, whose smooth surfaces touch one ano∣ther, the force of the Air does mainly make them cohere; yet it seems that generally in Bodies (whether greater or smaller) it is a sufficient cause of Cohesion that the parts of the Body are at rest by one another, though perhaps the entire Concretion be remov'd from place to place. For Bodies of sensible bulk being either fluid or consistent, and it being (as above we have taught) the chief requisite of a fluid Body that its small parts be in motion, there seems not any thing necessary to keep a Body from being fluid, and consequently to keep it a firm Body, but that its contiguous parts be in a state of rest.

I know that almost all Philosophers both ancient and modern, require something else than the Rest of the parts (of which scarce any of them takes the least notice as of a thing conducive to Firmness) to the keeping together the parts of a dry and stable Body. But although to en∣gage very far in such a Metaphysical and nice Speculation were unfit for me, (at least at present, when I am but to endeavour to explicate Fluidity and Firmness in the sen∣sible Bodies we converse with;) yet we dare not quite skip it over, lest we be accus'd of Overseeing it. The greater number of Contemplators ascribe the effect un∣der Consideration to a certain substantial form, to which they assign, among other Offices, that of keeping all the parts united into one Body. But what this form is, and by what means it unites the parts so strongly in a Diamond or a Ruby, &c. and so loosely in Tallow, Camphire, or the like slight concretions, and how the substantial form con∣tinuing the same in Water and Ice, the same matter may easily and frequently become by turns a hard and a fluid

Body; how these, I say, and diverse others things are ef∣fected by the forms of solid Bodies, is to me, I confess, at least as difficult to conceive, as to imagine without it a cause of Cohesion in the parts of a dry Body.

Other Learned Men there are among the modern Na∣turalists who have recourse some of them to a Spirit, which penetrating and fastening to each other all sub∣stances corporeal, unites them into one World; but others fancy rather a certain Cement or Glue, whereby they conceive the parts of Bodies to be made as it were to stick to each other. But as for this last Hypothesis, it would be consider'd, that though Glue is made use of to joyn together Bodies of sensible bulk, yet Glue it self being a Body that is so too, it must also it self consist of lesser parts sticking to one another; which allows me to de∣mand the cause of the mutual Coherence of those parts. And if it be answer'd, that they likewise stick together by the Intervention of some more subtil Glue, I shall again represent that this Glue also must consist of corporeal parts; and therefore I shall further demand how these also stick together: and if the like Answer be again made me, I shall still renew the like Demand, till at length the An∣swerer be reduc'd to confess, that parts of Matter so very small cannot be reasonably suppos'd to be kept together by a Cement. And if the Corpuscles that make up the finest Glue imaginable are not kept together by a Cement, we may be allow'd to ascribe their Adhesion to the imme∣diate Contact and Rest of the component parts, (which is a cause intelligible, and at least probable) till some other sufficient cause be assign'd, which I do not take that to be which is taught by the Patrons of the first Hypothesis lately mention'd, concerning a Spirit diffus'd through the mass of matter. For not to mention that the Agility of a Spirit seems not so proper a Qualification for that which is to fasten Bodies together, we may consider, that this sub∣stance

which is called a Spirit is indeed but a subtil Body. And why therefore may not the minute parts of other Bodies, if they be conveniently shap'd for Adhesion, stick to one another, as well as stick to this Spirit? And I should here also demand, how the parts of this Spirit are kept fast to one another. If any should answer, That this Spi∣rit consists of parts which are inseparable, and yet per∣haps of a hooked shape, which fits them to fasten them∣selves to the Bodies they take hold of, and thereby those to one another; this would be to propose such a new No∣tion of the diffus'd Spirit, as I know not whether those whose Opinion I have been examining did ever dream of, or would be content to adopt: and sure according to this Hypothesis there must be a wonderful plenty of these lit∣tle Spirits in the grossest Bodies; and Ice for example, which is thought so destitute of Spirits, must be well-nigh half made up of them: For these little spirituous parts can fasten no parts of other Bodies together but those they touch, since otherwise the parts of other sorts of mat∣ter, if but contiguous, might cohere without these, which is against the Hypothesis. And since each of these small spirituous Corpuscles, if I may so call them, being really a natural Body, and by consequent necessarily divisible, at least by Thought, into parts, I shall ask the Proposers of this new Notion of Spirit, upon what Account this Cor∣puscle can be indivisible; I mean, what it is, if it be not Rest and immediate Contact, that hinders but that the parts (or designable parcel of corporeal substance) which are divisible by thought, should be alwayes kept toge∣ther, and never be actually divided. I am not averse in∣deed from granting, that they may almost alwayes es∣cape Dissolution: but I am apt to suspect that may be, because that by reason of the extreme smallness, and the Rest and strict Contact of their parts, they can scarce ever meet with an Agent minute and swiftly enough mov'd,

to be able to shatter them or dissociate the combin'd parts. For to say, that 'tis the Nature of every such Corpuscle to be indivisible, is but to give me cause to demand how that appears: For so important an Assertion needs more than a bare Affirmation for proof.

And if two of these Corpuscles that are presum'd to be indivisible should, being smooth and of the same figure, (as for Example Cubical) happen to lye upon one ano∣ther, and a third should likewise chance to be fitly plac'd upon the uppermost of the two, what should hinder but that this Aggregate may by the violent knock of some other Corpuscles be broken in the midst of the whole Con∣cretion, and consequently in the middlemost body? For suppose them as Adamantine as you please, yet since Cor∣puscles as hard as they are, can be made very violently to knock against them; why may not these grate or break the middlemost Corpuscles, or any of the others? as we see that Diamonds themselves may be reduc'd to powder by other Diamonds, though not (as Artificers vers'd in the Trade inform me) by Attrition with any other stone. To prove that the Cohesion of the middlemost of the three lately-mention'd small Deyes with the other two, the one above it, the other below, is not so strong as that of the parts of that middlemost Corpuscle, notwithstanding that the contact between each two adjoyning Bodies is suppos'd to be full, (for so it must be in such Bodies, though not alwayes in others visibly greater, in which some subtiler substance may be suppos'd to come in part between them;) to prove this, I say, there must be assign'd some better cause of the Cohesion of the matter in one part of the propos'd Body than in the other. And it cannot with probability be pretended, that a Corpuscle presum'd un∣capable to be divided should consist of hooked parts: and if that should be pretended, yet ev'n these hooks also ••e∣ing true Bodies, the Question would recur concerning

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Them and be still renewable in infinitum. If it should be said that these minute Bodies are indissoluble, because it is ••heir nature to be so; that would not be to render a Reason of the thing propos'd, but in effect to decline rendring any. And though I know that in every Hypo∣thesis about the principles of things, something is allow'd to be assum'd, as not being to be explain'd or prov'd by any thing more primary than it self; yet I know not whe∣ther this excuse be proper in our Case, wherein it seems that the entireness and permanency of any parcel of mat∣ter, how minute soever, may be probably enough de∣duc'd from the immediate Contact, the Rest and the ex∣treme littleness of its designable parts. And if for a last refuge it should be said, that the designable parts of these Corpuscles are therefore unseparable, because there is no vacuity at all intercepted between them; besides that this is contrary to the supposition formerly made; for such extremely minute Deyes as we imagin'd to be one upon another, having their surfaces according to our Po∣stulatum, flat, smooth, and exquisitely congruous, could no more than the parts of either of the three Corpuscles have any vacuity intercepted between them: besides this, I say, this is both to suppose a Vacuum in all divisible Bodies, and that too as the cause of their being such, and to decline the former Hypothesis touching the use of this Spirit, and take Sanctuary among the Atomists, to whose opinion about the account upon which those Bodies they call Atoms are not dissipated, although some of the Con∣siderations we have alledg'd against the newly examin'd opinion may in part be appli'd; yet diverse of their other opinions do so fairly comport with the generality of our Experiments in these Notes touching Fluidity and Firm∣ness, that I am willing to decline clashing with them, by not pursuing now any further a Disquisition, which, as I said a while ago, is not necessary to my present design: espe∣cially,

since the dim and bounded Intellect of man seldom prosperously adventures to be Dogmatical about things that approach to Infinite, whether in vastness or littleness. Nor indeed would I have that look'd upon as a resolute Declaration of what I think of so abstruse a Subject, which I have rather propos'd to avoid saying nothing, where I suppos'd it expected I should say something.

The other thing then, which in our Description of a firm Body we mention'd as capable to make it so, is the tex∣ture of the parts (whether homogeneous or not) that con∣stitute it; and though the Juxta-position and Rest of these parts may possibly alone suffice to make the Body stable; yet this Texture seems to be the most usual cause of stabi∣lity, and sometimes also it may superadde a degree of that quality to that which bodies may have upon the former ac∣count only. For, though whilst the parts of the Body are actually at rest it cannot be fluid, yet those parts, if they cohere to one another but by rest only, may Caeteris pari∣bus be much more easily dissociated and put into motion by any external Body actually mov'd, than they could be if they were by little hooks and eyes, or other kind of fasten∣ings intangl'd in one another; it being often necessary in this case violently to break off these fastenings before the little bodies fasten'd together by them can be disjoyn'd, and put into such a separate motion as is requisite to the consti∣tuting of a fluid Body.

We formerly made use of that familiar substance, the white of an Egge, to illustrate the nature of Fluidity: Let us now try whether it will also assist us in our enquiry after the causes of stability. When an Egge is made hard by boyling, since whether we suppose this Induration to be effected by bare motion or impulse, or else by the insinuation of fiery Corpuscles, since I say there is nothing that appears to get in at the shell, unless perhaps some calorifick Atoms, and perchance too some little particles of the fluid water it is

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boyled in, 'tis not easie to discover from whence else this change of consistency proceeds, than from a change made in the texture of the parts whereby they are connected and dispos'd after a new manner, fit to make them reciprocally hinder the freedom of each others motions. But if instead of hardning the whites of Eggs by the heat of the fire, you beat them very well into froth, you may perceive that froth to emulate the nature of a stable Body: for not only you may raise it up to a pretty height, and make it retain a sharp top almost like a Pyramide; but I remember I have for cu∣riosity sake made with a little care a long and proportio∣nably thick Body of these bubbles hang down from my fin∣ger without falling, like an ice-icle from one of the Reeds of a thatch'd House, and yet in this there appears not any alteration to be made in the fluid Body, save a meer Me∣chanical change of the disposition of its parts: which may be confirmed by water beaten into froth, for there the heaped bubbles will quickly subside and fall back into wa∣ter of the very same consistence it was of before.

Now there may be several things whereby a body may be put into such a texture as is convenient to make it firm or stable. And of these, before we consider of them parti∣cularly, it will be fit to take notice in general, that for the most part 'tis not from any of them Single, but from two or more of them Concurring, that the Stability of Concreti∣ons proceeds.

The first and chiefest of these seems to be the fitness of the shapes of the component particles to fasten to each o∣ther; as if some were figur'd like the handles of Buckets, and others like the hooks, that are wont to be employ'd to draw them up out of the Well, or some like buttons, others like loops, some like male, others like female screws (as Me∣chanicians speak) or as if many together were so variously branch'd, that their parts may be so interwoven one with∣in another, as not to be easily separable (as we often see in

a well-made dry hedge, of which if a man go to pull away one bough, he shall often be unable to do it without pulling away with it diverse others whose slender twigs will be in∣tangled with it.) An eminent example of the power of the bare Texture of many small Bodies (even such as each of them apart is not perhaps extraordinarily shap'd for such a purpose) to make a stable one, is afforded us by Ropes and Cables; where only by twisting together and wreathing the slender and flexible threds the Cable is made up of, they are so well as it were wedg'd in between and fasten'd to one another, that they constitute a Body not to be broken by the weight of an Iron Anchor, nor perhaps by the force of a Ship violently driven on by the fury of the Winds and Waves. This figuration of the Corpuscles that make up consistent Bodies, seems to have been the chief if not only cause of their consistence in the Judgment of the antient Atomists, this being the account that is given of it by Lucretius.

Denique quae nobis durata ac spissa videntur, Haec magis hamatis inter sese esse necess' est, Et quasi ramosis alte compacta teneri. In quo jam genere imprimis adamantina saxa, Prima acie constant, ictus contemnere sueta, Et validi salices, ac duri robora ferri, Aeraque quae claustris restantia vociferantur.

And indeed, so innumerable may be the correspondent figures which are fit to fasten bodies to one another, that it is very possible that two bodies, whereof each a part is fluid, may upon their Conjunction immediately intangle their parts in one another, and thereupon acquire such a new texture, that their parts cannot as formerly dissociate them∣selves at pleasure, and move along one anothers surfaces, nor consequently flow after the manner of Liquors, but are

so connected or intangled, that the motion of one of them will be resisted by many, and so the whole Body will be∣come firm or stable. Something like this may be seen in the Experiment mention'd by our Author, where he teaches that the distill'd Liquor of Nitre, and that made per Deliquium out of fix'd Nitre, will presently upon their mixture in part concoagulate into saline and consequently stable Bodies: but this seeming only a re-union of the sa∣line particles that did, though invisibly, swim up and down in the aqueous parts of the mingled Liquor, which after this separation remains both more copious than the sa∣line parts, and as fluid as before, we will adde a noble in∣stance (mention'd to another Purpose by Lully and Hart∣man) to declare how much the firmness of bodies depends upon their t••xture. If you take then the Alchool or highly-rectify'd Spirit of Wine, and exquisitely deflegm'd Spirit of Urine, and mix them in a due proportion (as I remember the last time I made the Experiment I took about equal parts by guess, though two of the former to but one of the latter, if This be excellent, be a better Proportion;) you may in and about a minute of an hour turn these two fluid Liquors in∣to a constant Body; and •• confess it was not without plea∣sure, that I have immediately upon the shaking of these two Liquors seen them shoot into the likeness of Snow, and ac∣quire such a consistence, that I could without spilling the mixture turn the vessel that contain'd it upside down.

But I dare not expect to have this Experiment believ'd ev'n by most of them that shall try it, Experience having taught me, that it will not succeed, unless the Spirits of U∣rine and of Wine be both of them more exactly deflegm'd than is usual even among Chymists. Yet so much more does this coagulation seem to depend upon the Salt of U••ine as of such a texture, than barely as U••inous, that we will add that, As the spirit of fermented Urine is not (whatsoever some eminent Chymists may think or say) so indispensably re∣quisite,

but that my curiosity leading me to try whether o∣ther Liquors, which I suppos'd to be of a resembling na∣ture, might not serve the turn, I found that sufficiently-re∣ctifyed Spirit of Harts-horn (to mention that alone here) may be made to supply its place: So I endeavour'd to make it probable by this, That having try'd a certain method (though that may seem strange to most Chy∣mists) of so ordering Urine,* 1.2 that without staying at all to ferment or putrifie it either forty days or half so many hours, I can make the volatile or saline Spirit ascend first in distillation though I use but some such gentle heat as that of a Bath: Having, I say, by this means distill'd a very strong Spirit of unfermen∣ted Urine, and rectify'd it too, I found, as I expected, that I could not by any means make it coagulate with Spirit of Wine, which seem'd to proceed from the differing texture of this Spirit from that of Fermented, or rather Putrify'd, Urine, since I had added nothing to the fresh Urine I di∣still'd, but what was extreamly fix'd and belonging (as Chy∣mists speak) to the mineral Kingdom. Wher••upon having had the curiosity to enquire of some of my Chymical ac∣quaintances, I found that they complain'd that they had not been able to coagulate Spirit of Wine with the saline Spirit made of meer Urine, without any addition at all, when they distill'd that Urine without a previous putrefa∣ction (which is not wont to be perf••cted under six weeks or thereabouts.) But to return to our Coagulum we will annex, That this is further remarkable in this Experiment, that this whi••e coagulated substance being put into a glass vessel exactly stopt and kept in a gentle heat (which yet it self is not pe••haps necessary, though expedient) for some weeks or months, will at least for the gr••atest part by much (for I have not yet totally seen it do so) resume the fo••m of a limpid Liquor; as if eith••r all the c••ooked particl••s that conn••cted the small coalitions of the Vinous and Urinous

Corpuscles to one another, were by the motion they were put into by the external heat one after another broken off, or else the same little concretions (for the Menstruum seems to consist chiefly of them, being able to perform o∣ther matters than either of the single Liquors whereof 'tis constituted) either afflicted by outward warmth, or inab••ed thereto by some other cause of mobility, did after many and various attempts to clear themselves of each other, lit∣tle by little so unbend or break off the crooked particles that intangled them, as at length to extricate themselves, and become capable of freely shifting places among them∣selves, and so of the form of a Liquor.

And here I shall adde a couple of Experiments for the sake of their affinity with some parts of the newly recited Experiments about the Vino-Urinous Coagulate.

And first it seem'd to me worth trying, whether some Acid Salts being duly order'd would not concoagulate with Spirit of Wine, as well as with Urinous Salts; and having for a while digested together in a convenient pro∣portion pure Saccharum Saturni, made with Spirit of Vi∣negar, and rectify'd Spirit of Wine, I found the mixtures so chang'd in point of Consistence, that upon inclining the Glass which contained it, none of it would run down the Sides. But this Experiment did not afterwards seem to me either easie or consistent, nor is it more then one of the ways, and I doubt none of the best, of attempting what we have propos'd.

The other Experiment I promis'd you, relates to the re∣solution of the Coagulum of Spirit of Wine (which to be performed by digestion requires a very long time) And I wish I had not some reasons to hinder me from communica∣ting to you the way of making of it at present; it being an Experiment that seems somewhat strange in its kind; but that part of it which is directly pertinent to our present Argument, you will, I trust, believe upon my Relation,

which is, that by the addition of nothing but of a very fixt and very dry Body (insomuch that 'twill not yield any thing by the common way of distillation even in a naked fire) by the sole addition, I say, of this dry Body, the newly mention'd Coagulum, which is also a consistent Body, may in a few hours be brought into a permanent Liquor (quite distinct from the dry Body) which when Experience first recommended this way to me, was of too subtle and pene∣trating a Nature, not to make me expect from it considera∣ble Effects, both in Chymistry and Physick, of which imi∣tation you may be pleas'd to take notice.

But to return to what I was about to subjoyn after the mention of our Coagulum, as that is an Example of firm∣ness produced by Texture; I will here, because it is not easie to procure Spirits pure enough to make such a Con∣cretion as that. I will here, I say, set down another way of speedily hardning one fluid Body by another; for if you take the white of an Egge, and beat it till it become thin, and then shake well into it about half its quantity (perhap•• much less might serve the turn) of right Spirit of Salt, you shall have in a few minutes the mixture so coagulated, that I remember when we turn'd the glass wherein we made it upside down, not a drop of Liquor did run out, though some hours after we obtain'd a little by breaking the crud∣led matter. And another Experiment much of the nature of this is said to be delivered by Sir Francis Bacon, who teaches to coagulate whites of Eggs with Spirit of Wine: and indeed, if you observe a circumstance (unmention'd, that I hear of, by him) which is the shaking of the two Bo∣dies well together, and if your Spirit of Wine be good, the Experiment will succeed very well, insomuch that I re∣member I have made this way a Coagulum, from which no Liquor would drop down in about a minute of an hour. But whereas this great Naturalist conceives this hardning of the Egg's white to be perform'd by the heat of the Spirit

of Wine, I shall willingly confess he has assign'd the cause ingeniously, but must doubt whether he have done it truly: for there are diverse things that seem to argue Spirit of Wine, as inflammable as it is, to abound with a piercing Salt, and that such saline Corpuscles may suffice to crudle whites of Eggs, our freshly-mention'd Experiment of crud∣ling the white of an Egge with Spirit of Salt does sufficient∣ly declare; and not only we have perform'd the like effect with some other Acid Spirits, and particularly that call'd Oyl of Vitriol, but it may be produc'd, though more slowly, ev'n by a crude Salt; for by long beating the white of an Egge with a lump of Allum, you may bring it for the most part into white cruds. So that if we will allow the coagulation we treat of to be performed by the Spirit of Wine as hot, it seems that that heat must be only such as may be ascrib'd to the active particles of saline bodies, which yet are commonly accounted rather cold than hot. But because I somewhat doubt how justly they are reputed so, I will adde, that I did purposely for tryals sake, take the Serum or Whey that is wont to swim upon mans Blood after it is cold and setled, and indeavour'd in vain to coa∣gulate it with such Spirit of Wine as would coagulate Eggs, and yet this whey will at least as soon as (if not much sooner than) whites of Eggs coagulate over a gentle heat of Embers; which makes it doubtful, whether the effect proceed not from the greater correspondency in tex∣ture of the Spirit of Wine with one of the Liquors than with the other, rather than from the heat ascrib'd to it, which did not at all coagulate the whey.

But although we have mention'd some Examples to shew that two fluid Bodies may be associated into a consistent one; yet we want not an Experiment to make it appear, that likewise by the change of Texture a fluid Body may be divided into two consistent ones. This Experiment which we have partly taken notice of before (treating of

Fluidity) is, that having for tryals sake by convenient de∣grees of fire distill'd over a due proportion of the more volatile parts of f••llet Oyl, neither the Liquor that came over, nor the substance that remain'd behind in the Retort was fluid, though the Oyl that yielded them had been so.

But when I put to the Oyl before Distillation a conve∣nient quantity of common Salt, and one or two other things, that were fit to change the Texture of the branch'd or hookt Corpuscles whereof it consisted; I could then obtain an Oyl of common Oyl, that both dropt into the Receiver in the form of a Liquor, and continued a Fluid Body; which may probably be of good use to Surgeons, Varnishers, and Men of some other Professions.

And to make it the more likely, that by Additaments of some such nature as that newly mention'd, some g••••sser and cloggy parts are retain'd, or else much subtiliz'd ••nd otherwise altered. I shall adde that pros••cuting 〈◊〉〈◊〉 I happen'd to meet with in the discourse of a 〈…〉〈…〉 Chymist, I practis'd a way so to desecate the 〈…〉〈…〉 muddy Oyl of Am••er drawn per se, that a pretty 〈◊〉〈◊〉 of it would come over so transparent and 〈◊〉〈◊〉 lour'd, that the Experiment did not a little please 〈◊〉〈◊〉 shew'd it to. And if it do not appear upon tryal, 〈◊〉〈◊〉 this way of preparing Oyl of Amber does by detaini•••• some parts, which though more gross then the rest, may yet be no useless one; impair the Remedy, and that it does not, upon some other score infringe the medicinal vertue of the Oyl, the Experiment will not be unuseful. For the Liquor that is thus prepared is not only very dia∣phanous and well colour'd, but so pure and subtle that 'twill swim, not only upon Water, but upon Spirit of Wine it self. And 'twill be no despicable thing, it by ex∣tending or further applying this Experiment to other in∣dispos'd Bodys, many Empyreumatical Oyls distill'd by

strong fires in Retorts, can be brought to emulate essential Oyls (as Chymists call them) drawn in Limbicks, as to clearness and lightness.

The additament I last thought fit to make use of for pu∣rifying Oyl of Amber was briefly this. ℞. Two Pound or somewhat less of good Brandy, One Pound of good Sea-Salt, and half a Pound of the Oyl to be subtiliz'd, mix and distil them together.

Upon the mention I made above of the white Coagu∣lum of the Spirits of Wine and Urine, I remember what I have sometimes observ'd in the essential Oyl of Anni∣seeds (as Chymists speak) distill'd with store of water in a Limbick and Refrigeratory, nam••ly, that in the heat of Summer it would remain a perf••ct Liquor like other Chy∣mical Oyls; but during ••he cold of the Winter, though they, notwithstanding that season, continued fluid as be∣fore, the Oyl of Anniseeds would coagulate into a Body, though not of an uniform Texture to the Eye like Butter (but rather almost like Camphire) yet like it white and consistent, not without some kind or degree of Brittleness.

And on this occasion I will here insert an Experiment which should have been set down in that part of the for∣mer History of Fluidity, where I mention, that the small parts of a Body may be sufficiently agitated to constitute a Liquor by the Air or other Agents not se••sibly hot them∣selves. The Experiment take ••hus. Casting by chance my Eyes in the Winter time upon a glass of Oyl of Anni∣seeds which stood coagulated by the cold of the season, I presently bethought my self of making a Liquor (whose process belongs to another Treatise) of which as soon as I had prepar'd it I made this Tryal. I melted with a gentle heat the congeled Oyl of Anniseeds to make it flow, and then cover'd par•• of it in another glass wi••h a Mix••ure I had provided: and h••ving let th••m both rest in the window,

I found, that the meer Oyl being fully refrigerated again, coagulated as before; but that which was cover'd with the other Liquor continu'd fluid both day and night, and in several changes of weather, and does still remain at the bottom of the Menstruum a clear Oyl distinct from it, though I have purposely shaken them together to con∣found them.

And because, Pyrophilus, I have not discover'd to you the Menstruum I made use of, I will here present you with a Succedaneous Experiment made with a common Liquor. I took then good clear Venetian Turpentine, and having slowly evaporated about a fourth or fifth part of it, till the remaining substance being suffer'd to cool would afford me a coherent Body, (or a fine Colophony) I caus'd some of this transparent and very brittle Gum (of which I have elsewhere taught you some uses) to be reduc'd to fine powder: of which I put into pure Spirit of Wine a greater proportion, then I judg'd the Liquor was capable of dis∣solving, to the end that when the Spirit had taken up as much of the Powder as it could, there might remain at the bottom a pretty quantity of our Colophony. On which, though the Menstruum (being already glutted) could not act powerfully enough to dissolve it, yet it might give the matter (which it had already so far softened, as to reduce it into a coherent mass) agitation enough to emulate a fluid (though somewhat viscous) Body. And accordingly I obtain'd a sluggish Liquor, which continued fluid, as long as I pleas'd to continue the Menstruum upon it. The like Experiment I try'd with clarify'd Rosin, and with fine Colophony, though but bought at the Shops; and although the Tryal sometimes succeeded not ill, yet I found not the success constant and uniform, whether be∣cause the Bodys to be dissolv'd were not defecated and pure enough, or that I did not hit upon the best proportion between the Solvent and them. But this circumstance I

shall not omit, that when the glutinous Liquor was se∣parated from the Menstruum, it would by degrees, though but slowly, harden in the Air. The Application of which property, for the preservation of small and very tender Bodies, I shall not here more expresly hint then by having barely nam'd it. I had forgot to adde, that whilst the substance continu'd fluid, I could shake it, (as I lately told you •• could the Oyl of Anniseeds) with the su∣pernatant Menstruum, without making between them any true or lasting Union.

Which last circumstance brings into my mind another Experiment that I likewise forg••t to adde to that part of the former History of Fluidity, where I take notice, that the particular Textures of fluid Bodies may be reckon'd among the chief causes of their being dispos'd, or indis∣pos'd to mingle with one another. For partly to confirm this Conjecture, and partly to manifest that 'tis not uni∣versally true which Chymists are wont to think, that A∣cid Salts and Oyls will not incorporate or mingle; I took an arbitrary quantity (and, as I remember equal weight) of common Oyl of Vitriol and common Oyl of Turpen∣tine, as I bought them at the Druggists: these I put to∣gether very slowly, (for that circumstance should not be omitted) and obtain'd according to my desire an opacous and very deep-colour'd mixture, whose almost Balsam-like consistence was much thicker than either of the Liqu••rs that compos'd it. (The like Experiment also succes∣fully try'd with some other Chymical Oyls, but found none preferable for this purpose to Oyl of Turpentine.) And to make it probable that the disposition of these Li∣quors to mingle thus presently together depended much on their Texture, we made the mixture be war••ly ••••s••ill'd over, (for else the Experiment will searce suc••eed) a••d thereby obtain'd, (as we elsewhere men••ion to another pu••pose) a certain gross substance, which was that which

seem'd to mediate the former union betwixt the two Li∣quors. For this substance being separated, and thereby the Texture of one of the Liquors (or perhaps both) being chang'd, the Liquors (which came over very clear into the Receiver) swome upon one another; nor have I since been able by shaking them together to confound them for any considerable time, but they presently part again, and do to this day remain distinct as well as transparent. But af••er having forgot to set down these things in their proper place, I must not forget also, that to employ here more words about them were to digress.

To this then annex we, that the Liquor we elsewhere mention our selves to have distill'd from Benzoin, has been and is still subject to much more frequent vicissitudes of Fluidity and Firmness; for part of it all the year long continues in the form of a blackish Oyl, and the rest ac∣cording as the season of the year or of the day makes the weather cold or hot, frequently changes its Texture, sometimes appearing perfectly the same with the newly-mention'd Oyl, and sometimes shooting into clear and va∣riously-shap'd Crystals, which fasten themselves to the bottom and sides of the Vessel, till a warmer part of the day or of the Season resolves them again into a Liquor. And these two last Observations may also serve to confirm what we formerly taught, that the Fluidity of some bodies de∣pended almost wholly upon the various agitation of their parts: for in there instances the parts of the Anniseeds and those of the B••nzoin, upon the operation or absen••e of the languid heat of the ambient air, sometimes agitating them, and sometim••s suffering them to rest, did constitute a fluid or a consistent Body. An•• h••ving thus taken no••ice of this upon the by, we will 〈◊〉〈◊〉 the other Examples mention'd under this second head, that which it a••forded as to ou•• presen•• purpose by Salt-P••tre, which being ••issolv'd 〈◊〉〈◊〉 ••••fficient quantity of common water, will seem to be lost

in it, and to constitute with it one uniform fluid substance; but if a competent quantity of that water be boil'd (or per∣mitted to exhale) away, and the remaining liquor be suf∣fered to rest a while, especially in a cool place, the sa∣line particles will be re-uniting themselves and by the ex∣clusion of the aqueous parts, constitute stable and deter∣minately-figur'd Ice-icles or Crystals.

The consideration of this may suggest to us another way, that seems quite contrary to the former, whereby some bodies may become firm and solid, and that is by the inter∣mingling of a due proportion of water or some other Li∣quor. For, though the small parts of such fluid Bodies, being themselves in motion, are apt to give those of others such an agitation as we have formerly taught that Flui∣dity principally depends on; it seems that the admission of any Liquor must rather conduce to the making of a body fluid than consistent; yet if we consult Experience, it will instruct us otherwise; for when I have taken either an equal or a double weight of Oyl of Vitriol and di∣still'd it warily from running Mercury; very much the greater part of the Liquor would come over, and leave behind it a very white Powder considerably fixt. And if we examine that familiar Production of Chymistry, Mer∣curius dulcis (which they now use to make by subliming of together two parts of crude Mercury, with but one of Sublimate, which consists chiefly of Mercury already) we may find that in That which is counted the best, the fluid Body of Quick-silver is so contex'd with the Salts it carries up in Sublimation, that the dry and brittle Body they compose may contain far more (perhaps twice more) Quick-silver than Salt. And other Experiments may per∣swade us, that the mixture of a convenient Liquor may ce∣ment bodies into one hard Concretion, which would scarce be compacted together otherwise. Nor is it against rea∣son that it should be so; for there may be differing quali∣fications

required to a body whilst it is constituting, and when it is constituted, and though the motion of the parts that make it up, oppose the firmness of a formed body, yet it may conduce to the making of a firm body: for when a great many hard Corpuscles lye together loose and incoherent, they do, as we formerly noted, emulate a fluid body; whereas by the mixture of a Liquor, those loose Corpuscles being for a while dissociated and put into mo∣tion, they may after many Evolutions apply themselves to one another after that manner that is most requisite to make them touch one another closely, and according to a greater surface. Whereupon it often follows, that the Liquor in which they did formerly swim is either squeez'd out upon their closing, or else so dispers'd in small parti∣cles, and dispos'd of among those of the harder Corpuscles, that they are unable to agitate them, or prejudice their mutual cohesion.

And here to dilucidate the subject under consideration by an instance that seems very pertinent to it, we will make a further use of the Experiment formerly mention'd touch∣ing the burning of Alabaster: For if the powder, after it has done boyling and has been sufficiently burnt, and kept some hours (the most experienced Artificers observing that it is not so convenient to employ it presently after it is taken off the fire) be well beaten and tempered up with fair wa∣ter almost to the consistence of thin pap, if the powder have been rightly prepar'd and skilfully temper'd, you shall see that fluid substance in a few minutes of an hour b••gin to set (as the Trades-men speak) that is to exchange its Fluidity for Firmness, so that if it were b••••ore cast in∣to a mould, it will perfectly retain the figure of the internal surface thereof.

Now that in our mixture there is for a while such an agi∣tati••n of the hard parts produc'd upon the aff••sion of ••he wate••, and a••t••rwards an ••xc••usion of the s••perfl••••us wa∣ter,

we may confirm partly by this, That when any con∣siderable quantity of burnt Alabaster is temper'd up with water, the mixture after a little time grows sensibly hot, and sometimes continues so for a pretty while: and partly also by this, That having purposely for tryals sake fill'd a new and good Glass-Vial, containing about half a pint, or pound, with the mixture we speak of, and when it was top full, stop'd it up very close, the liquid mixture within less than half an hour crack'd the Vial (though standing in a window) in several places, and at those crevises discharg'd it self of about a spoonful of clear water, the remaining mixture retaining perfectly the figure and dimensions of the Vial, and growing as hard as Chalk or somewhat harder, insomuch that we were fain to imploy several strokes with a strong Iron to divide the mass.

And let me here adde, that some other substances may this way afford much solider Bodies than burnt Alabaster does: and therefore it may be a thing of good use to en∣quire out and try what other Bodies, easily to be procur'd, may be thus brought to a new and lasting Solidity. For the Learned Hydrographer, Fournier, speaking of those Damms or Digues (as he calls them in his Language) which are sometimes made in the Sea to secure Shipping, (as I have seen at the Port of Genoa and elsewhere) after ha∣ving told us that the Romans made the fairest Harbours in the World by the help of a certain Sand to be met with at Cuma and Puteoli in the Kingdome of Naples, which Sand mingl'd with a third part of Quick-lime ac∣quires in the water a flint-like hardness;,* 1.3 sub∣joyns this Observation of his own, J'ay veu, &c. that is, I have seen (sayes he) in Flanders near Tournay a certain sort of ashes of Lime made of Mar∣ble, which was excellent for any kind of work made in the water. For having made a Bed of great stones, they cast upon them whole Baggs full of such ashes instead of Mor∣tar,

and the water betwixt the stones having temper'd up these ashes, petrify'd them to that degree, that in a short time they became as hard as Marble. Thus far He. But to pursue our former Discourse.

That also which we intimated of the conduciveness of the various tumblings to and fro of the hard particles to their uniting into one firm concretion, seems confirmable by what we have observ'd in some saline Liquors, especi∣ally certain parcels of Spirit of Harts-horn, which what∣ever were the constitution of the ambient air, rem••ind fluid some of them for many months, after which the sa∣line Corpuscles began to shoot at the bottom of the re∣maining Liquor into exquisitely-figur'd Crystals, which at length grew copious enough. For this spontaneous coagu∣lation of the little saline Bodies happening so late, it seem∣ed that it was preceded by almost innumerable evoluti∣ons, which were so many and so various, that at length the little bodies came to obvert to each other those parts of themselves by which they might be best fasten'd toget•••••• and consti••ute a firm body. Which conjecture seem'd t•••• less improbable, because we could not well imagine th•••• this coagul••tion proceeded (as that of dissolv'd Allum and other Sal••s is wont to do) from the evaporation of the superfluous Liquor; for the Glasses wherein what we have mentioned happen'd being carefully stop'd, there was no danger of such an avolation, and if any thing could get a∣way, it must have been the subtil peircing and fugitive Spi∣rit, (which indeed, as my Nose had inform'd me, does of∣tentimes penetrate ordinary stopples) for the flying away of those volatile parts would only have left the remaining Liquor more aqueous. And 'tis well known to those that deal with such kind of Liquors, that the more a∣queous they are, the l••ss apt they are to Crystallize. And however it will serve our turn, that there was but an insensible diminution of the Liquor upon the

recesse of whatever it was that got through the Cork.

To the same purpose I remember also, that having in a Crystal Vial carefully kept a pretty quantity of well-co∣lour'd Tincture of Amber, made with pure Spirit of Wine, it remain'd fluid for a year or two, and during that time presented us with a strange Phaenomenon that belongs to other papers. * 1.4 But having been absent for two or three years from the place where we lock'd it up, we found, when we came again to look upon it, that that though it had formerly remain'd fluid so long, yet several yellow lumps of Amber, almost like Beads, with one side flat, had here and there fasten'd themselves partly to the bottom, and partly to the sides of the Glass: the rest of whose internal surface continues yet transparent.

Another thing whereby bodies become stable is, the ad∣mission of adventitious Corpuscles into their Pores and re∣cesses. And of the wayes by which these foreign Corpus∣cles may bring the substance they invade to be compact, these four appear the chief.

First then, the adventitious Corpuscles we speak of may produce stability in the matter they pervade, by expel∣ling thence those voluble particles which, whilst they continu'd in it, did by their shape unfit for cohesion, or by their motion oppose the coalition, or disturb the Rest of the other particles whereof the Body consisted. But of this having already discoursed, proceed we to what is to follow.

In the next place then, foreign Bodies may contribute to the stability of a substance they get into, by hindering the motion of the little Bodies that constitute it.

And thirdly, such advenient Bodies, especially if they be not of the smallest size, may produce a firmness in the sub∣stance

which they get into, by constituting with the par∣ticles it consists of, Corpuscles more unapt for motion, and fitted for mutual cohesion.

These two we mention together, because that very of∣ten Nature imploys them together for the introducing of stability into Matter.

To these seems to be reducible the way of turning the fluid body of milk into cruds by the mixture of a little Runnet, whose saline particles pervading the body of the milk, do not only make a commotion in the parts of it, but fasten the branched particles of it to one another, and with them constitute a body of another texture than was the milk; and the weight of these crudled bodies reducing them by degrees into a closer order, does, whilst it presses them together, squeeze out the thinner and more serous Li∣quor, which the Runnet was unable to coagulate, and which being thus sever'd from the grosser parts of the milk, may well be more fluid than milk it self is wont to be. And that there is some coalition of the particles of the Runnet with the coagulated ones of the milk, may ap∣pear by the complaints that Houswives sometimes make of their Dairy-maids, that the Cheeses tast too strong of the Runnet, when too great a proportion of it has been mingled with the milk. And though we ascrib'd the crudling of the milk to the saline particles of the Runnet, we ignore not that not only common Runnet, but also di∣verse juices of herbs will crudle milk, as is well known in thole parts of Italy where Cheese is made without Runnet. But we made especial mention of the saline Corpuscles of the Runnet, because really Houswives are wont to salt it, and because saline Liquors do manifestly and powerfully operate in the coagulation of milk, which may be crud∣led by juice of Limons, and I know not how many other Acid Salts. And to manifest yet further the coagulative power of them, we have sometimes in about a minute of

an hour arrested the Fluidity of new milk, and turn'd it into a crudle substance, only by dexterously mingling with it a few drops of good Oyl of Vitriol. But of the ef∣fects of various Salts upon milk we elsewhere may, and therefore shall not now, discourse.

Between this last recited Exp••riment, and the two fol∣lowing ones, 'twill not be improper to insert the immedi∣ately ensuing one, for the Affinity which it seems (in different respects) to have with both.

I remember (then) that I divers years ago prepar'd a Salt, which either was, or at least answer'd well to the qualities ascrib'd to that which is now called Glauberus's Sal Mirabilis, which seem'd to have in it a coagulative power, in reference to common Wa••er. For whereas Salt of Tartar, Common Salt, Ni••re, &c. being dissolv'd in Water, do upon evaporation of a sufficient quantity of ••hat Water, recover indeed their pristine Saline Forms, yet they do but coagulate themselves, without concoagula∣ting with them, either any Water, or at least so much, as Chymists have thought worth the taki••g no••ice of: Whereas this Salt we speak of, being p••epar'd for the pur∣pose, and dissolv'd in a convenient quantity of Water, does upon its recoagulation so dispose of the aqueous Par∣ticles, among its own Saline ones, that if the Experiment be well and carefully made, almost the whole mixture will shoot together into fine Chrystals that seem to be of an uniform Substance, and are consistent enough to be even brittle, and to endure to be pulveriz'd, si••ted, &c. though the Concretion may have such a Proportion of Water in it, that (as I remember) when the Experiment succeeded well, from three parts of Water and but one of Salt, I had about four parts of Crystals.

I need not tell you that this Salt s••ems to have a some∣what more then ordi••ary Res••mblance of a ••rue Coagu∣lum, since it reduces so much water into a stable consi••tence;

yet it does in no contemptible proportion materially con∣cur to the Body produc'd. But I may hereafter (which I must not do now) entertain you about a Salt of a diffe∣ring kind from this; and which put me upon considering, whether there may not be a Coagulum more properly so call'd of Common Water, which may in a very small pro∣portion operate upon a great quantity of that Liquor, as Runnet does on Milk.

I have not yet examined whether it will be sufficient to refer meerly to the second and third ways lately menti∣on'd of making Bodies become stable in the Phaenomena I am about to speak of, or whether it may be reasonably suppos'd (and added as a fifth way) that the Bodies to be coagulated may (in great part) be brought to be so; by so acting upon the Bodies to which they are put, that the Agent Liquor (if I may so speak) does by its action com∣••unicate to the subject it works on, or lose upon some o∣ther account some sub••le parts whose absence fits the dis∣pos'd remaining Fluid for such a Cohesion, as may suffice to make a Body be (though very soft, yet) consistent. But however 'twill not be amiss to take some notice of Effects, which, what e're the cause be, belong to the History of Fluidity and Firmness.

I some years since prepar'd a Substance of a whitish co∣lour, which would not only destroy the Fluidity of some other Liquors, but would give a consistency to a notable proportion of Oyl of Vitriol it self, though the par••s of this Liquor be presum'd, upon the score of its corrosi••e∣ness, and i••s aptness to grow very hot with many other Bo∣dies and make them smoke, to be very vehemently agi∣ta••ed.

And I remember that I sometimes shew'd the curious a Glass Vial well stopt, upon th•• bottom of which lay a lit∣tle of this newly mention'd whi••ish powder; ov••r which the••e was a considerable propo••••ion of Oyl of V••••ri••l▪ in a

consistent Form without seeming to have any thing to do with the Powder, as indeed it had been only pour'd upon it, and suffer'd to stand in the cold for some time (which if I mistake not was a day or two) at the end of which the above mention'd change was wrought on the Liquor by the powder which did not appear to be dissolv'd thereby. Which Phaenomenon seem'd indeed to argue, that there happen'd in this Experiment (that was not the only one of the kind I then made) something like the coagulation formerly mention'd of Quicksilver by the Vapour of Lead, some subtle parts of the Coagulator, if I may so call it, in∣visibly pervading the Liquor whose Fluidity was to be suspended, though it seem not improbable to me, that the effect produc'd might depend upon both causes, this newly express'd, and the other a little abovemention'd; where I guess'd that a change of Texture, and thereby of Consistence in the Menstruum, might be the result of the Operation of the Menstruum, and the Body it acts upon. And because this powder is not so easie to be prepar'd, I shall adde that you may (though not so well as by the newly mention'd way) see the Coagulation of a Menstruum upon a firm Body which it does not seem to dissolve by the ensuing Experiment, Take Crystals of Salt-Petre very well dryed, but not powde••'d, and gently pouring on it in a Glass Vial some good Oyl of Vitriol till it swim about half an Inch, or perhaps more above the Salt, leave the Vial clos'd with a cover of Paper in a cool quiet place, where it may not be shaken; and if the Tryal succeed with you as did it with me, the Liquor will, though slowly, so settle it self about the Nitre, that though you incline the Vial to any side (or perhaps turn it upside down) it will not run out; and I have sometimes taken notice of little Sa∣line Bodies, and as it were Fibres, that seem'd to keep the parts of the mixture united together. I made also some other Tryals to coagulate unflegmatick A. F. upon Nitre

and some other Bodies, the Phaenomena of which Tryals, did not oblige me to renounce the lately mention'd Con∣jectures about the causes of such changes of consistency in Liquors, as I have been speaking of: For I still think it highly probable that the best Coagulator I have met with acts but as a finer sort of Runnet, which in an inconsidera∣ble quantity really disperses material parts of it self through the Liquor to be wrought on, though these when the Coagulator is a consistent Body, be perchance so few or subtle as not to make any Visible diminution of the Body it parts with.

A more eminent Example to our present purpose may be afforded us Sometimes (for I am sure the Experiment will not Always succeed) by the notable way of coagula∣ting Quick-silver, and thereby turning it from a fluid into a firm body by the vapour of melted Lead, in which when it is taken off the fire (but before it be quite grown hard again) a little cavity must be made with a pebble or a stick, that the Quicksilver tied up in a rag may be nimbly put into that hole, and be congeal'd by the permeating stream of the cooling lead. Which Effect may be less hopefully expe∣cted by the way wont to be prescrib'd by Authors (most of whom I doubt never made tryal of it) then by another that I have practis'd and may on another occasion shew you. And that some metalline steam does really invade the Quicksilver, seems probable by the wasting of Lead by fusion, and by the operations ascrib'd by Chymists to the fume of Lead upon Gold, about which I may elsewhere tell you what is come to my Knowledge.

And I remember that not long since, an ingenious Phy∣sician of my acquaintance keeping some Lead long in fusi∣on to reduce it per se into a Calx, and holding his head of∣ten over rhe melting pot to observe the alterations of the metal, was suddenly purg'd diverse times both upwards and downwards, which both he and I ascrib'd to the Sa∣turnine

exhalations. And though I suspected the Congela∣tion formerly-mention'd might proceed from the egress of some subtil substance that formerly agitated, but after de∣serted, the Mercuria•• Corpuscles; yet that the Concretion of the Quick-silver might be effected by some benumbing vapour of the Lead, seems confirmable by a notable ac∣cident that befel that famous Geometrician Doctor Wallis, who related it to me as a Phaenomenon he knew not well what to make of; namely, That he and other Learned Men at Oxford being minded to make the Experiment un∣der consideration, they found that upon the first fusion of the Lead the immersed Quick-silver was very well co∣agulated by it; but when they came to melt it the second time, and put new Qui••ksilver into it, the Experiment would not succeed, at which they wonder'd, finding by Tryals that the Lead might be so easily deprived of its power of hardning Quick-silver. That this Observation will always hold true, I am not apt to believe; but that such Learned and Candid Naturalists should either be mi∣staken in making it, or mis-relate it, 'twere injurious to susp••ct: wherefore supposing that to have then at least happen'd which one of them registred in writing, and more then one of them told me; it seems to countenance what we have deliver'd, and looks as if according to our Do∣ctrine there were in Lead a coagulative steam or Spirit, and yet (at least in that parcel of metal) in so small a propor∣tion. as that it almost totally dislodges or spends it self upon the first opportunity it meets with of passing into Quick∣silver.

We have elsewhere to another purpose mention'd our having sometimes (for, as we there advertise, it will not always succeed) made an Experiment which seems of kin to the former, and may give much light to the matter un∣der consideration, and it was this; We pour'd upon Aqua fortis common Sallet Oyl, which floted together at the top

of it, but after some hours had its texture so changed by the ascending steams or other subtle insinuating particles of the saline Liquor, that it was turn'd into a white con∣sistent (and sometimes a brittle) body like Butter, remain∣ing all in one Cake on the top of the Menstruum. And the like Experiment (but in a longer time) we have perform'd with express'd Oyl of sweet Almonds instead of common Oyl.

And to shew further, how much the operation of the same visible Agent may be diversified as to the Production of Fluidity or Firmness, according to the differing dispo∣sitions of the Bodies it acts on. I have sometimes (I re∣member) taken the same Aqua Fortis, or Spirit of Nitre wherewith I had coagulated express'd Oyl of Olives, and having pour'd it off from the Butter-like Substance: I cast into it some good Camphire, which without heat was thereby reduc'd into an Oyl, that retain'd a distinct Super∣ficies from the Menstruum which it swam upon, and would not incorporate with, so that the same numerical Men∣struum without the help of any degree of fire, turn'd a brittle Body into a Liquor, and the Liquor into a brit∣tle Body (for such is the Substance that may be made of common Oyl, if it be suffer'd to float long enough upon the coagulating Liquor) which brittle Substance (to adde that upon the by) seem'd to have receiv'd a more durable alteration from the steams of the Menstruum then was ex∣pected. For not only when melted with fire, it would upon refrigeration recover its consistence without be∣coming again fluid, as when 'twas in the form of Oyl; but I made a Tryal or two without success to reduce it to a Liquor by mixing it with Oyl of Tartar per Deliquium, which, you know, has a great Faculty to find out and mortifie Acid Spirits, such as those of the Nitre or Aqua Fortis that had (whether as meer Acids I now examine not) coagulated our Oyl.

The fourth and last way whereby Corpuscles entring from without into a Body may give it a stable consistence, is by making such a commotion in the parts of it, as may make them apply themselves one to another according to a greater surface, or otherwise complicate and dis∣pose them after the manner requisite to make them stick together.

This way of making Bodies become consistent, is seldom or never employ'd by Nature without the concurrence of some of the other ways already mention'd: but we have distinguish'd it from the two last recited, because in them we suppose that some of the adventitious Corpuscles are stop'd in the body to whose firmness they conduce, and (though perhaps but in a very considerable proportion) do concur to make it up; whereas here we suppose that without materially concurring to constitute the body they work upon, they do only agitate and variously move the particles it consists of, perhaps breaking some, bending and twisting others, and in a word so altering the Tex∣ture, that the parts that did formerly either move sepa∣rately, or adhere together but loosly, are now reduced to a closer order, or a more implicated Texture, and there∣by more firmly connected to one another. That the bare disposition of the parts of a body in reference to each o∣ther, without any addition of forein matter, may do much towards stability, we may see both in some examples for∣merly mention'd, and in Osier wands, which when lying loosly in an heap together may each of them very easily be dissociated from the rest; but when they are breaded into a Basket, they cohere so strongly, that when you take up any one of them, your shall take up all the rest. To which may be added those many obvious though per∣haps unheeded Instances wherein by the bare Texture of the slender hair or filaments whereof Wool or Silk consists, Cloth, Silk-stockins, and many other durable

Garments are made by illiterate Tradesmen.

We may also observe the force of bare motion in altering the texture, and thereby the consistence of bodies by the common way of Churning, for there the external impulse of the Churn makes a great commotion in the parts of the Cream, and tumbles and shuffles them perpetually to and fro among themselves, whereupon it happens, that the more branched Corpuscles meeting with one another are in∣tangled, and thereby separated from the rest, and after ma∣ny occursions all these parts are at length fasten'd to one another, and excluding those of the Butter-milk, which seem not so conveniently shap'd for mutual cohesion, do constitute Butter; which is wont to be made yet more con∣sistent, or rather more compact, by being beaten or other∣wise compress'd, as the parts thereby reduced into a closer order squeeze out the fluid Butter-milk that was intercept∣ed among them.

It will perhaps be thought more strange that a fluid Bo∣dy, nay a distill'd Liquor which is very volatile and passes for simple and Homogeneous, and is at least far less com∣pounded than milk, should by motion, without the mixture of any new matter, be made coherent: and therefore I hope that it will not only second the Example newly alleg'd, but likewise confirm some main points of our Doctrine touch∣ing Firmness, if we observe that ev'n the Chymical Oyl of Turpentine, which passes for one of the Principles or Ele∣ments of that Body, may be in great part, if not wholly, coagulated without addition. And yet (not to anticipate what I may have occasion to deliver elsewhere concerning this Experiment) I shall now only relate, That enquiring a while since of a very expert Chymist, whether he had not sometimes observ'd (which I have often done, as I elsewhere declare) Oyl of Turpentine to begin to coagulate if it were often distill'd; he went with me to his Laboratory, and there let me see in a Receiver some Oyl of Turpentine

which he had often disti••l'd over per se, in good part co∣agulated into a whitish and consistent Body: affirming al∣so to me, that he had sometimes by frequent Distillations, without Addition, obtain'd from clear Oyl of Turpentine a far greater proportion of such a stable substance. Whose consistence, whether it should be ascrib'd to the fires break∣ing the Oyly Corpuscles into parts more fit for mutual cohesion, or whether it proceed from a new texture of the same Corpuscles, only chancing by those various Evoluti∣ons to be dispos'd after such another manner as to compli∣cate or otherwise connect them, I need not now spend time to enquire; since 'tis enough for my present purpose, that in this example we have one that declares, how much ev'n motion without the Addition of any sensible substance may in some cases conduce to Firmness.

And here to illustrate our Doctrine about this Quality and Fluidity, by shewing what the intestine motion of the parts, even without the assistance of adventitious heat, may do, to make a Body change its consistence according to the previous disposition of the matter, and become of firm, fluid: as we lately saw Oyl of Turpentine made of fluid, firm. I will adde on this occasion what I observed of Oyl of Wax distilled in a Retort with an Additament of the like nature with that I formery mentioned, when I spoke of the fluid Oyl drawn from Oyl of Olives. For this Oyl of Wax, though at first it came over for the most part, if not totally, in the form of a Butter; yet by standing on a shelf (and that not in a hot place, as a Stove or Laboratory) I observed it little by little to resolve into a transparent Oyl, and purposely enquiring of him that lookt after it, whe∣ther or no this effect might not be ascribed to the increased warmth of the Weather, he assured me of the contrary, ha∣ving taken notice what effects the changes of Weather had upon it.

But what if we should say, that fluidness and stability

depends so much upon the texture of the parts, that by the change of that texture the same parts may be made to con∣stitute either a fluid or a dry body, and that permanently too? These last words I adde, because of what may be said to this purpose concerning the change of water into Ice, and Ice into water, and of metals into fluid or hard bodies, by fusion and refrigeration: for in these examples the acquired hardness of water and fluidity of metals may be presently lost upon the bare removal of those bodies into a tempe∣rate air; whereas in the instance we are to give, the acqui∣red texture is so durable, that without an extream external violence, such as would destroy most other stable bodies, it is not to be destroyed. And this instance is afforded us by that admirable Repository of Natures wonders, Quick-silver: for if some Ounces of this fluid mineral be put into a convenient glass vessel, and that vessel be first exactly stop'd and kept for 6, 8, or 10 weeks (or longer, if need be) in a sand Furnace whose heat may be strong and con∣stant, the Corpuscles that constitute the Quick-silver will, after innumerable revolutions, and perhaps bendings, twistings, and other changes, be so connected to one ano∣ther, that instead of a fluid Body, they will appear in the form of a red powder, that Chymists Precipitate per se: which change is so unexampl'd, that though among the more curious Spagyrists it be very well known, yet many Naturalists cannot easily be brought to believe it; whom to convince of the possibility of it by a much less tedious preparation, I take half a pound or a pound of Quick-silver, and with a strong fire distil it out of a glass Retort, and for the most part there will remain in the bottom and about the sides of the vessel a little red powder, which seems to be nothing but part of the fluid body (most expo∣sed to the action of the fire) turned into a dry one eight or ten hours space.

After what manner the fire produces so odde a change

in the Quick-silver, I do not presume to know. 'Tis true, that though the parts of Liquors do, as we have formerly taught, touch one another but in part of their superficies, yet they all of them seem to have some degree of viscofity, or some slight and loose complication or other kind of Ad∣hesion of parts, as appears by their being so easily contex∣ed into those thin membranes or films we call bubbles, in∣somuch that not only Spirit of Wine, that seems the most light, and most fluid of Liquors: will afford bubbles, but (what may seem strange) we have divers times purposely observ'd, that Quick-silver it self, as ponderous as it is, es∣pecially being suffer'd to fall in a slender stream into a vessel almost full of the same mineral, will afford bubbles numerous and large enough, although (as those also of the Spirit of Wine) quickly vanishing.

And hence it might be imagin'd, that in the operation we are treating of some such change is made in the Quick-silver, as we formerly observ'd to be made in the white of a Egg, when by a new disposition of its parts, either heat or beating it makes it a kind of stable body, or else it might be pretended, that there is a variety of parts argu'd to be in Quick-silver by the great variety of its effects upon other bodies, and that by the frequent evolutions which the fire makes of those parts among themselves, they come at length to be so appli'd to one another, that either they lock into each other as it were, or slip upon one anothers sur∣face in such a manner as that as much of their surfaces immediately touch one another as is requisite to make them cohere, as we formerly mention'd of several very smooth pieces of glass mutually adhering without any other Ce∣ment than the congruity and immediate contact of their surfaces. But though these Conjectures and divers others might be propos'd, yet I fear all of them would prove but meer Conjectures. Nor were we much assisted to make better by looking upon our Mercurial precipitate in one of

the best Magnifying Glasses in the World; for what we there discover'd was only, that the red powder had in it many Corpuscles of sundry other colours, and that the little grains of powder seem'd to be of no determinate shape, but look'd like slender fragments of Red Coral: and having but some small dust of a shining precipitate of Gold and Mercury into the same Augmenting Glass, all we could discern was, that the little grains of this precipitate differ'd from those of that made of Mercury alone, in that these (which a Chymist would take notice of) were so transparent throughout, that one would verily think he beheld the best sort of those precious Stones-Gold-smiths call Granats. But though we pretend not to make out how the new Texture is produc'd in the Quicksilver, yet to make it still more evident that its change of consistence proceeds from its change of Texture, we will adde, that having a great curiosity to try whether our powder could not be made fluid again, I procur'd some precipitate per se of a Person who formerly lived with me, and was expert in many Mercuri••l operations, and presented me some of his own making: this being weigh'd and put into a conveni∣ent glass was carefully press'd with a naked fire (which should be stronger than that wherewith it was precipita∣ted) and at length it rose by degrees in fumes, which settl'd in the neck of the Glass in many drops of reviv'd running Mercury; all which being collected into one, we found that there wanted but about a sixth or seventh part of what we had put in, and we suppos'd we should not have want∣ed that neither, but that the vehemence of the fire had melted the glass, which swallow'd up a part of the powder that made a great shew through it, after what was colli∣quated had been remov'd from the fire.

This Experiment brings into my mind another that was judg'd uncommon enough, and it was This: Being not long since master of about half an ounce of a certain Mer∣cury,

which some ways of examining it that I had em∣ploy'd, induc'd me to think Mercury of Saturn; I ima∣gin'd (for some reasons) that it might be made very ser∣viceable to confirm our Doctrine touching Fluidity and Firmness. And accordingly I found upon Tryal, that I could, barely by shaking it long, reduce it to a black powder: in which form it would continue as long as I please to let it do so. And when to the By-standers there appear'd nothing in it that gave suspition of a fluid Body, I could in a Trice, only by dexterously rubbing it in a small Marble Mortar, reduce it little by little into run∣ning Mercury, as it had been before. Which quick pas∣sage from one quality to another, being made, not only without the help of Fire, but without adding or taking away any visible Substance, prov'd no ignoble Instance, how much Motion and Rest, and the thence easily result∣ing Texture of the Component Corpuscles of a Portion of Matter, may contribute to its Fluidity or Firmness.

From the Experiment of precipitating Quick-silver per se, and from some other things, partly deliver'd al∣ready, and partly to be deliver'd by and by, we may learn what to think of the opinion of some Eminent Modern Philosophers who teach, that a fluid body is always divi∣sible into bodies equally fluid, as Quantity into quanti∣ties, as if the particles of fluid Bodies must also be fluid themselves: for by them it seems to appear, that Quick∣silver, and some other other actually fluid Bodies consist very much of hard Corpuscles, since by the change of their Texture they may be deprived of their Fluidity and become stable. We see also that the stiff and solid par∣ticles of Salts dissolv'd in common water, and of Silver dissolv'd in Aqua fortis, being by those Liquors sufficient∣ly dissociated and separately agitated, do with them con∣stitute fluid Bodies. And we have elsewhere mention'd to another purpose an Experiment which may not imper∣tinently

be repeated here, namely, that by putting toge∣ther in••o a glass Retort one part of Quicksilver and four of common Oyl of Vitriol, and distilling them in a sand furna•••••• wi••h a strong fire, there remain'd in the bottom of 〈◊〉〈◊〉 V••ss••l a ponderous Calx or Powder, so far from bei••g f••uid▪ that it was but in par•• dissoluble in water: and that which seems to prove that in the very liquid Oyl of Vitriol, though a distill'd Liquor, the saline Corpuscles that chiefly compose it, do retain their stiffn••ss (generally to be found in undistill'd Salts) is, that by steeping our Calx in fair water, we could separate from it a considera∣ble quantity of particles, which upon the evaporation of the water coagulated into store of saline and bri••tl•• bo∣dies. And that these proceeded rather from the M••n∣struum than the metal, we were induc'd to think, b•• 〈◊〉〈◊〉 serving the dry Calx, before any water was pour'd on 〈◊〉〈◊〉: for though the saline part of the Mixture did not weigh (perhaps any thing near) so much as the Mercurial distinctly did, yet the Aggregate or Mixture did weigh a great deal more than the Quicksilver did when it was put in; and the Oyl of Vitriol that was abstracted, a great deal less than it did before it was committed to distilla∣tion. Nay, I once or twice observ'd in a glass, where I kept a quantity of Oyl of Vitriol, that there did sponta∣neously fasten themselves to the sides little saline Crystals, which when I took out, I found hard and brittle; but when I had for tryal sake expos'd them to the air, they presently resum'd a fluid form, and appea••'d to be Oyl of Vitriol. In the Observation also lately mention'd con∣cerning the spontaneous coagulation of Spirit of Harts∣horn, it seems evident, that Bodies which are all or most of them hard, and appear so when they are commodiously connected to each other, may yet constitute a fluid body when they are reduc'd to sufficient smallness, and put into a convenient motion. And indeed, if the least par∣ticles

of fluid bodies were not (many of them at least) in∣dowed with their determinate bigness and shapes, but that such fluid bodies could be always divided into particles fluid also, how comes it to pass that some Liquors cannot pie••ce into or moisten some bodies which are easily pervi∣ous to other Liquors? for if the particles of the excluded Liquor were of necessity always divisible into fluid ones, there seems no reason why they should not be sub-divided into so very small ones, as that no pores can be suppos'd lit••le or odly figur'd enough to keep them out.

'Tis true indeed, that as it is hard to demonstrate, so it is not easie to disprove, that the matter whereof fluid bodies consist is capable of b••ing indefinitely divided: and it may be granted too, that by how much the smaller parts a body is divided into, by so much the more easily, Caeteris pari∣bus, are the parts of that body to be put into motion. But this divisibility of a fluid body into perpetually lesser and lesser parts belongs not to it properly as it is Fluid, but as it is a Body; such divisibility, if suppos'd true, being a primary affection of matter it self, and belonging as well to those portions of it that are hard as to those that are fluid. And though it were admitted, that such an end∣less division as is presum'd might be made Mentally (as they speak in the Schools) that is by the thought or operation of the mind, yet it would remain a great question whe∣ther o•• no N••ture does actually so far mince and sub-di∣vide Bodi••s: as may appear by what has been freshly no∣ted. And ••owever, it is not only requisite to the constituti∣on of a fluid body that the parts of it be small enough, but that they be also actually mov'd. For we observ'd not long since, that the dust of Alabastar put into motion did (though its Corpuscles were not insensible) emulate a fluid Body, and immediately ceas'd to be fluid when they ceas'd to be agitated: whereas the particles of water, as minute and apt as they are to constitute a fluid substance, do yet

make that hard and brittle body we call Ice, when those little particles upon what account soever are reduced to be at rest.

By what has been hitherto discours'd, we may also be assisted to judge of the Doctrine of the Chymists, who teach that in all Bodies, Coagulation, Stability, Hardness and Brittleness depend upon Salt: for though what above has been said of Crudling of milk by saline Liquors, and the hardness and brittleness obvious in Salts themselves, may keep us from denying that the saline principle is very powerful in the coagulation of some bodies, and does pro∣duce much firmness or even brittleness in many or most of the concretes wherein it is predominant; yet this hard∣ning power of Salt seems not to proceed from any peculiar and inexplicable property it has to coagulate other bodies or make them compact, but from the shape and motion of its Corpuscles, which it seems are more fitted by Nature than those of many other Concretes to insinuate them∣selves into the pores of other bodies, and fasten their par∣ticles to themselves, and to one another, either by wedg∣ing their Corpuscles together, or by their stiff and slender parts, or their sharp angles or edges piercing diverse of them together; as when many Pieces of Paper are kept from scattering by a Wire that runs through them, or as when a Knife takes up at once diverse pieces of Bread and Meat by being stuck into them all. But whensoever there is in the constituent parts of the body a sufficient fitness and disposition to adhere firmly to one another, Nature may of those parts compose a stable body, whether they abound in Salt or no, it not being so much upon Chymical Prin∣ciples, or ev'n upon the Predominancy or Plenty of any one Ingredient, as upon the shape and motion of the component parts of bodies, that their Fluidity and Firmness depend. I will not here urge that Salts are generally reducible by an easie mixtu••e with water into the form of Liquors; nor

that Sea-salt, Salt of Tartar, and diverse other sorts of Salts, will of themselves, ev'n in the Air, if not very dry, assume the form of fluid Bodies; nor yet will I press the shortly to be mention'd Example of Coral, which is con∣fidently affirmed to be soft whilst it remains in the Salt water, and to grow hard when taken out of it. I will not here, I say, press these and the like Arguments, but con∣tent my self to have hinted them, because they are such as I cannot well in few words make out and vindicate. Wherefore I shall rather demand, what Salt can be made appear to pass out of the body of melted Lead into that of Quicksilver, to perform in it the coagulation abovemen∣tion'd? What accession of Salt is there to be observ'd, when running Mercury is precipitated per se into a pow∣der? and how will it be prov'd, that when in a well-stop'd glass the whole body of water is in frosty nights turned in∣to firm Ice by the cold of the ambient air, that coagula∣tion is perform'd by Salt, it having not yet been made ap∣pear by Chymists, that either Salts or even the distill'd Spirits of them can penetrate, without a kind of Prodigy, the narrow pores of unheated glass? It is usually observ'd in Eggs, that though at their first coming out of the Hens belly, the shells are soft, yet soon after they grow hard and brittle; and yet it appears not how the saline Ingredient is encreas'd to effect this speedy induration: and (to sub∣joyn that by the by) albeit I am not averse from thinking that the coldness of the outward Air, and its imbibing some of the loosest of the moist parts of the soft Egge-shell, may concur to this effect; yet there are many Observati∣ons of Egge-shells that have been found hard in the womb of the Hen. And I well remember I have taken notice, that diverse Eggs not yet laid, but found at one time in the body of the same Hen, were each of them furnish'd with a compleat and brittle Shell. But I think I can draw a much stronger Argument against the Chymical opinion

from the consideration of an Egg: for I demand what plenty of Salt can be made appear to pierce the hard shell, and more close-wrought membrane that both lines it and involves the Egg, especially since 'tis certain, that in Egypt and diverse other places Eggs may be hatch'd by a tempe∣rate external heat without the Hen. And yet we may here observe, that the same internal substance of the Egg which at first was fluid, the yolk and white that compos'd it being so, is upon the exclusion of the Chick turn'd almost all of it into consistent Bodies, some of them tough, as the mem∣branes and gristles of the Bird, and some of them harder and almost brittle, as his bones and beak; and all this as we said without accession of new Salt. It would be hard for Chymists to prove, that Diamonds and Rubies, which are counted the hardest Bodies we know, (and at particular tryals of whose hardness I have sometimes wonder'd) do abound in Salt; at least it will not be unreasonable for us to think so, till Chymists have taught us intelligible and practicable wayes of separating (at least some) true Salt from either of those Jewels. And it may be also doubted whether the blood of Animals when it is freest from Se∣rum, do not (though a Liquor) as much abound with Salt as their skins or their flesh.

And since 'tis with Chymists that I am now Reasoning, I presume I may be allow'd to press them with Arguments drawn from some of the Eminentest Writers of their Sect. For the generality of Chymists, and ev••n those that are by the rest, and themselves too, call'd Philosophers, not only granting, but asserting and maintaining the Transmutation of great quantities of Quick-silver and the other ignobler metals into Silver or Gold by means of the white or red Elixir, I shall demand of them whence it happens, that one grain of the powder of Projection can turn a whole pound of Mercury into true Gold or Silver, and consequently change a very fluid Body into a very firm one, though the

proportion of Salt employ'd to coagulate the whole Mass of Quick-silver would not amount to the six thou∣sandth or seven thousandth part of the Liquor; though we should grant that the powder employ'd to work this mar∣vellous change were all of it Salt, to which yet Chymical Writers seem to ascribe much more of the sulphurous Na∣ture. And to this I shall adde, what the famous and acute Helmont does to another purpose relate upon the Experi∣ence of Raymund Lully and his own, concerning his prodi∣gious Liquor, Alkahest; namely, that being abstracted from common Quick-silver, it does in a quarter of an hour coagulate it: and yet in this coagulation he points at this as a singular Phaenomenon, that this Liquor which is as well immortal as exceeding saline,* 1.5 leaves nothing of it self with the Mercury on which it works, and yet so coagulates it, that he prescribes the making it into a subtil powder.

I remember also to our present purpose, that a Physitian of much veracity in what he relates, discoursing with me the other day about an odde preparation that he saw at the present Duke of Holstein's, (that Learned Prince and great Chymist) assur'd me that among other things he there took notice of a glass of Spirit of Urine, which in warm weather remain'd in the form of a L••quor, but in cold weather did totally coagulate into Cry••talline salt: and being ask'd by me if he knew how this Urinous body had been prepar'd? he answer'd me, that the Duke caus'd Spirit of Urine exceeding rich in volatile Salt to be distill'd very many times; after every Distillation re-conjoyning all that came over in a Liquid with that which remain'd in a saline form, till by very frequent cohobations all the parts of the Urinous substance were brought to the union or coa∣lition above-mention'd. What we may propose concerning the various consistence of the saline part of Urine upon our own knowledge, we shall for certain Reasons reserve for another place.

And on this occasion we will annex a few particulars, which may tend not only to the making of the Chymical Hypothesis about the coagulation of bodies doubtful, but to the confirmation of much of the Doctrine by us propos'd. The first shall be an Observation afforded us by the Art of making Sugar, wherein very great care is taken, that no∣thing acid (and especially juice of Limons) fall into the Caldrons or other Vessels wherein the juice of the Sugar-Cane is to coagulate into Sugar: for though acidity be ge∣nerally by the Chymists ascrib'd to Salt, yet here the sa∣line bodies are so far from promoting the coagulation of the saccharine sirrup, that they would quite hinder it. And because that through the want of Sugar-Canes in these parts, we are reduced to take this Observation upon the credit of others, and because also in it self it seems some∣what strange, we will vouch for it two eminent Authors in whose Writings we met with it. The one is the ingenious French Publisher of the natural and moral History of those American Islands, commonly call'd by the French Les Isles Antilles, and by us the Caribe Islands, who describing par∣ticularly how his Country-men make Sugar in those parts,* 1.6 gives this caution towards the latter end; Sur tout, &c. that is, Above all, great heed must be taken to let no juice of Citrons (or Limons) fall into the Caldrons, for that would absolutely hinder the formation of the Sugar. The other is the diligent Gulielmus Piso, who having given us a particular account both by words and pictures of the way of making Sugar, tells us that, Si momentum succi Limonis vel acidi quid injicia∣tur, sacchari consistentiam nunquam acquiret,* 1.7 sed in totum perditur. To which I shall adde, that having purposely inquir'd concerning this Ob∣servation, it has been confirmed unto me by Persons that pretend more than ordinary knowledge of the Art of order∣ing Sugar: which likewise affords us another Observation

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not impertinent to the Theme we treat of; for the best Authors that write hereof inform us, that the juice squeez'd out of the Sugar-Canes is wont first to be boild and depurated in vast Vessels of Copper or Brass, whence it afterwards is convey'd to be further purifi'd and coagu∣lated into smaller ones; and that whilst it is in the former, they use to pour upon it some very strong Lee to facilitate the separation of its feculencies, as in the smaller ones 'tis usual to pour a little Oyl or Butter upon the boyling juice, to keep the sirrup from boyling over. Now that which they further observe to our purpose, is related almost after the same manner both by our French Author and by Piso, and by the latter of them in these words, Observatu dignum (sayes he) si oleum majoribus inderetur ahenis in quibus Liquor primus,* 1.8 Caldo dictus, purifica∣tur, saccharo conficiendo plane foret ineptus: vi∣cissim si minoribus lixivium sicut majoribus in∣fundatur, aequè impossibile saccharum conficere. So much the Fluidity and Firmness of bodies depend upon their tex∣ture, how much soever Chymists would have them depend upon Salt.

But to this borrow'd Observation, though borrow'd of Authors not to be distrusted, we will adde two or three Experiments of our own, which we hope may the more confirm the Doctrine by us propos'd touching Stability in Bodies, because it was our aim in them to bring light by them to the matters we treat of.

First then, we prepar'd a Liquor elsewhere to be de∣scrib'd, which is almost if not altogether as saline as Aqua fortis it self, or any other acid Spirit that is commonly known: and yet when in this Liquor we laid fragments of solid Harts-horn of several sizes to steep, ev'n in a cold place, the Menstruum was so far from hardning them, that it would (without dissolving them as corrosive Liquors do metals) gently pierce into them and soften them, so that

in about two or three dayes it would reduce them to a kind of white slime or mucilaginous substance at the bottom of the Liquor. We took also good salt of Tartar, and on it pour'd good Spirit of Vineger, as long as the affusion of it would produce any ebullition: Then we distill'd off the Liquor, which came over almost insipid, the saline parts that make Spirit of Vineger so sharp, being retain'd by the Salt of Tartar: Upon the remaining dry mixture we pour'd fresh Spirit of Vineger as long as any hissing ensu'd thereupon, and afterwards abstracted the aqueous parts of this parcel of Liquor also, and so we proceeded, till ha∣ving sufficiently impregnated the fix'd Salt with the saline parts of the distill'd Vineger, we obtain'd according to our desire a mixture which (though it were all made up of Salts, and such Salts too as being made by the Chymical Analysis of the Bodies whence they were drawn, may according to the Chymical Doctrine be look'd upon as pure and Ele∣mentary) was yet so neer Fluidity, that it requir'd not the heat of the fire to turn it presently into a Liquor, which shape it assum'd with a gentler warmth than one would ex∣pect from a saline Body. Lastly, we took common Oyl of Vitriol, and cast into it diverse little pieces of Camphire, which floating upon it were by degrees and after some hours wholly reduc'd into a reddish Oyl, that was to be seen altogether upon the top of the other Liquor. Then having fo••merly try'd that Oyl of Vitriol would easily mix with common Oyl, we try'd also by shaking the saline and Camphorate Liquors together to unite them, and ea∣sily confounded them into one high-colour'd Liquor, which seem'd very uniform, and continu'd so (at least as to sense) for many hours. Then we added to this mix••ure three or four times as much fair water, and (as we expect••d) the Camphire immediately recover'd a white consistent Body, and by degrees setled at the top of the L••quo••: where we m••y observe, that the Camphire is no•• made hard bu•• fluid

by its mixture with the saline Corpuscles of Oyl of Vitriol, and exchanges its Fluidity for Firmness upon the affusion of Saltless water. And thus much it may suffice to have said touching the Chymists deriving the stability of Bodies from their abounding in Salt.

And as for the hardness and brittleness they ascribe to the same principle, how much they may be increas'd or di∣minished in a body without the acc••ssion or decrement of the saline principle or ingredient, may appear by that Ex∣periment mention'd by us to several purposes, of tempering a slender piece of Steel; for when it has been sufficiently heated, by plunging it red hot into fair water, which is more likely to dissolve than increase its Salt, you may make it not very hard alone but very brittle, whereas by only suffering it to cool leisurely in the air, it will be both much less hard and more tough, and if after having quench'd it in cold water you again heat it till it have attain'd a deep blew, it will become (comparatively) soft and very flexi∣ble, and that not from any wasting of the saline ingredient by the fire, for if this softn'd steel be again heated red hot and suddenly refrigerated, whether in water or otherwise, as before, it will re-acquire both hardness and brittle∣ness.

Now that by these operations a real change is made in the disposition of the small parts of the steel, we have else∣where evinc'd ev'n by a sensible proof. And that by procu∣ring a closer order & more immediate contact of the parts of a body, a man may without encreasing the Salt encrease the hardness of it, is, as we formerly also no••ed, obvious in Snow, which whilst it lies in flakes as it falls upon the ground, composes but a soft and yielding body: But when the same snow is by being strongly press'd every way be∣twixt the hands formed into Balls, the little whether Iceicles or frozen bubbles it consists of are so approach'd to one another, and forced into an order which allows so little

wast of room, that the formerly-intercepted spaces being most of them fill'd up with little bodies, the Iceicles can no longer yield as they did before to the pressure of a mans fingers, but constitute a mass considerably hard, which yet may be made harder being melted into water, and after∣wards frozen into Ice; for this having been a fluid Body, (and in such, Room is wont to be better husbanded than in others) the bubbles intercepted in it cannot keep it from being of so close a texture as to be considerably hard.

I know that not only profest Chymists, but other per∣sons who are deservedly rank'd amongst the modern Phi∣losophers, do with much confidence entirely ascribe the induration, and especially the Lapidescence of bodies to a certain secret internal principle, by some of them call'd a form, and by others a petrifying Spirit, lurking for the most part in some liquid vehicle. And for my part, having had the opportunity to be in a place where I could in a dry mould and a very elevated piece of ground cause to be digg'd out several Crystalline bodies, whose smooth sides and Angles were as exquisitely figur'd as if they had been wrought by a skilful Artist at cutting of pretious Stones, and having also had the opportunity to consider divers other exactly or regularly shap'd Stones and other Minerals, some digg'd out of the Earth by my friends, and some yet growing upon stones newly torn from the Rock, I am very forward to grant, that (as I elsewhere intimate) it is a pla∣stick Principle implanted by the most wise Creator in cer∣tain parcels of matter, that does produce in such concre∣tions as well the hard consistence as the determinate figure. We deny not then, that these effects depend most common∣ly upon an internal principle, but the difficulty consists in conceiving how that internal principle produces its effects, which these Writers not pretending to explicate intelligi∣bly, we thought it not amiss briefly to survey some of the

principal ways by which it seems that Nature makes bo∣dies firm and stable, whereby we may be assisted to judge whether it be as necessary to have recourse to a plastick Principle or a Gorgonick spirit in all other quick and no∣table Indurations of Bodies in the cold, as in the hardning of such Bodies whose curious and determinate either in∣ternal Textures or outward shapes (common to several Concretions of one kind) argue their having been fram'd by some one formative power, or by diverse seminal Principles conven'd together. But this we will do with∣out affirming either that she cannot by some other yet unobserv'd way make consistent bodies, or that of the ways by us discours'd of, she is wont so to confine her self to any one, tha•• she does not frequently make use of two or more of them to produce the same effect.

And because Hardness is a high degree of Firmness, I suppose it will not be impertinent to shew by some exam∣ples how small an external operation may without any ap∣pearing adventitious Salt make a soft body hard, and even brittle, when there appears not any other change to be made than that of the Texture or disposition of its com∣ponent particles.

It is a Tradition amongst Naturalists, that Coral grows soft at the bottom of the Sea, but when it is brought up in∣to the open Air, though it retains its bulk and figure, it hardens into a stony Concretion, according to that of Ovid.

Ovid. 15. Metamorph. Sic & coralium quo primum contigit auras Tempore durescit, mollis suit herba sub undis.

Whether or no this Tradition is strictly true, we had no•• opportunity when we staid at Marseilles (whose neighbou∣ring Sea is the chiefest in Europe where Coral is wont to be fish'd) to give our selves an ocular satisfaction. But what∣ever

some say to dis••redit the tradition, nay, how confi∣dently soever Beguinus (who seems to have the most strong∣ly argu'd against i••) hath rejected it, it must not be deny∣ed to be, sometimes at least true, (and that's enough to serve our present turn.* 1.9) For the Learned Gassendus in the Life of Piereski∣us, relating how that incomparable Gentle∣man had the curiosity to fish for Coral near Toulon, (a no∣ble Port not far from Marseilles) has among other things this passage, (viz.) The plants which were pluckt up and drawn out were neither red nor handsome till their Bark was pull'd off; in some parts they were soft, and would give way to the hand,* 1.10 as towards the tops, which being broken and squeez'd they sent forth milk, like that of Figs. I remem∣ber likewise, that the Learned Jesuite Fournier, who being also a French Hydrographer, and one that writes of Mar∣seilles and Toulon as places very well known unto him, may be safely credited on this occasion, after he has par∣ticularly describ'd the way of fishing Corals near Toulon, he adds, These plants are neither red nor polish'd when they are drawn out of the water, till their Rind have been taken off, nay, they are soft, and being brok••n or else squeez'd betwixt the fingers, they throw out a kind of milk resembling that of Figs; and when one leaves off pressing them, he may see the small holes or pores that harbour'd the milk that was squeez'd out. Thus far He.* 1.11 The credible∣ness of a good part of these narratives has been confirmed to me by a practiser of Physick in the East-Indies, who having made some stay at his return on the Island of Mehila, (near that of Madagascar) where store of white Coral is reported to grow, I enquired of him whether he had gathered any, and whether he found it soft whilst it was growing? and he an••wer'd me, that he

had of late years diverse times gather'd Coral upon the Sands of that Island, and found it, when he gather'd it, ex∣ceeding white, and (to use his expression) as soft as an O∣nion, adding, that though it would in a very short time grow hard in the air, (which he ascrib'd, how justly I know not, to the external heat of the Sun) yet it is very well known to the Sea-men that deal in that ware, that if it be not gather'd at a seasonable time of the the year it will not keep long, but either crumble away or otherwise decay, which disagrees not with the experienc'd Piso,* 1.12 who in his natural History of Brasil, speaking of some places of the Brasilian Coast, where diverse stony plants, some like little Trees, some otherwise fram'd, may be seen in clear weather growing in the bot∣tom of the Sea, tells us, that, è fundo erutae mox durissimae, sí insolentur in littore, siccae niveique coloris fiunt. As re∣markable a change is that I meet with in Scaliger, who tells us as upon his own knowledge of some, who at the Urinary passages voided a slimy matter, which in the Air coagulated into a firm substance; the story being memo∣rable, take it in his own words thus: Ex bovillis oppida∣nus nostris adjutus medicamentis eminxit vitrum sane ex illa nobili Paxagorae pituita, dum mingeretur albuminis mollitie emissum vitri duritie ac splendore, Senatoris filius ejecit, pultis modo multos, & maximos: qui aeris contactu postea in gypseam tum speciem tum firmitatem concrevere; hic quoque nunc rectè valet. Having likewise had the ac∣quaintance of an inquisitive Merchant of Dantzik, and also of an ingenious Chymist, that spent some time in that City and the neighbouring Country, along whose coast our European Amber is wont to be dragg'd out of the Sea, I enquir'd of them, whether they had never observ'd in Amber a property like that which is reported of Coral: and one of them, as I remember the other also, hath as∣sured me upon his own particular Observation, that lumps

of Amber are sometimes taken soft out of the Sea, and grow hard in the Air; which is the more credible to me, because I have at a Polonian noble-mans seen (besides other intercepted things) a whole Spider, and that none of the least, perfectly inclosed in a piece of hard and transparent yellow Amber. And elsewhere I have seen ten or twelve (if I mis-remember not the number) pi••ces of such Am∣ber, which contain'd, one a Fly; another a Spider, a third a Straw, and each of the rest some such other thing. And it seems not impossible, that the contract of the external air may put the parts of such small Bodies into a new motion, whereby some voluble Corpuscles that hinder their reciprocal adhesion may be excluded, and the parti∣cles themselves prest or otherwise dispos'd into a closer order; and we find that some Oyl-colours, after they are brought to their due temper, may be preserv'd very long in the same degree of softness, if they and the shells that contain them be kept all the while under water, whereas in the air they would quickly change their Texture, and become dry and h••rd.

But though in this last mention'd Example, and some others the removal of the body out of the water into the air seem manifestly to contribute to its growing hard, yet it seems not to us so easie to determine what share the air has in effecting such indurations: for Gassendus relates of Piereskius, that he being wont in the Summer time to wash himself in one of the lesser streams of the River of Rhosne, he there made the following Observation. Once upon a time he felt the ground, which he had wont to find even and soft, to be grown hard with little round balls or bunches,* 1.13 like hard boiled Eggs when the shell is peel'd off; at which won∣dring, he took some of them up, and carried them home, that he might shew them to his Master, and demand of him the Reason. But the miracle was increas'd when a

few days after returning to the River, he found those little balls or lumps turned into perfect pebble stones, which he observ'd likewise to befal those which he had carried and laid up at home. But how far this story will prove that such coagulations must be effected by a sub∣stantial form or a petrifying Liquor, we define not, espe∣cially since, not to repeat what we deliver'd already touch∣ing calcin'd Marble out of Fournier, we have elsewhere deliver'd upon our own Observation, that two or three spoonfuls of such pap of burnt Alabaster as we have lately been speaking of, (and instead of which Artificers use a∣nother stone call'd by them Plaster of Paris, burnt and and temper'd up with fair water) did in the bottom of a vessel-full of water into which we pour'd it in a short time coagulate into a hard lump, notwithstanding the water that surrounded it; which, it seems by the Texture of the mass, was kept out of its pores, as it is out of those of the Oyls of Cinnamon and Cloves, which though fluid bo∣dies, and sinking in water, suffer not its particles to insi∣nuate themselves into theirs: and Artificers observe, that the coagulating, property of burnt Alabaster will be very much impair'd, if not lost, if the powde•• be kept too long, especially in the open Air, before it be made use of; and when it has been once temper'd with water and suf∣fer'd to grow hard, they tell me they cannot by any burn∣ing or powdering of it again make it near so se••vic••able for their purpose as before; so much doth the co••gulation of these powders mixt with water seem to depend upon their Texture and other Mechanical qualities.

I remember also, that though the bones found in the Hearts of Deer, and so magnified by Physicians, do in the air acquire a hard and bony consistence; yet having had the curiosity to consider one of them in the Heart of a Deer newly kill'd, I found it there of a cartilaginous softness and flexibility.

And here I will adventure further to confess, that I have oftentimes doubted whether or no not only consistent Bo∣dies but some of the most solid ones in the World may not have been fluid in the form either of Steams or Liquors, before their coalition and their concretion either into stones or other mineral Bodies. I know there are many who think that Stones, Marchasites, and other such solid and durable Bodies, were made together at the Creation or other beginning of the Universe, and who will not ad∣mit that such concretions can be now generated. But not here to debate that famous Controversie, whether stones may be said to grow and to be nourish'd, in the strict sense of those Expressions, I think it not difficult to shew that such parcels of matter are now to be me•• with in the form of stones as did not before appear 〈◊〉〈◊〉 ••hat form, but whilst it was divided into minute 〈…〉〈…〉 was it self some fluid Body or other, or at 〈…〉〈…〉 as a material part concur to the constituting 〈◊〉〈◊〉 that was so. Of this, besides what we elsewhere 〈◊〉〈◊〉 concerning it, we shall anon have occasion to 〈◊〉〈◊〉 some proofs; and therefore we shall now o••∣ly mention ••wo or three instances. The first whereof shall be, that we saw, among the Rarities of a Person ex∣ceedingly curious of them, a stone fl••t on the out∣sides, on one of whose internal Surfaces was most lively engraven the Figure of a small Fish, with all the Finns, Scales, &c. which was affirmed to have been enclosed in the Body of that stone, and to have been accidentally dis∣cover'd, when the stone chancing to receive a rude knock upon its edge, split asunder. I remember also that a while since a House-keeper of mine in the Country inform••d me, that whilst a little before he caus'd in my absence one of my Walls to be repair'd, the Mason I was wont to employ casually breaking a stone to make use of it about the Build∣ing, found in it (to his wonder) a piece of Wood that

seem'd part of the branch of some Tree, and consequent∣ly was afterwards enclos'd with that solid case wherein he found it. This cavity in the body of the stone and, as I remember, the stick it self he took out of it, he forth∣with brought my House keeper, to whom I have given di∣••ections to send them me. For this example seems to me a more cogent proof of the increase of stones, than some others that eminent Naturalists much rely on, for Reasons discours'd of in another place: where we also make particular mention of that Ghur or Me∣talline juice,* 1.14 which though the Latin Writers of Chymical and ev'n of Metalline matters have not, that I remember, given us any ac∣count of, yet I find a German or two, that were ve∣ry conversant in the Mines themselves, to have in Books written in their own Language taken a special notice of it. Besides, I have at present something to deliver upon my own Observation, which unless we will suppose (what seems not probable) that there were from the beginning made together with and in the midst of great Masses of one kind of Mineral little parcels of another of a quite diffe∣ring sort, seems manifestly enough to argue, that either whole quarries of stone, or heavy and shining Minerals, or both, may have been fluid Bodies. The Observation whereon I ground this Conjecture is, not only that we have met with in Lead-oar and also in Minera Antimonii par∣cels of a white stone or spar environ'd with a Metalline body, though I think I have yet by me such lumps of Oar; but chiefly that I have with my own hands taken a hard and ponderous shining Mineral, which I keep for a Rarity, like a Marchasite, of the shape of a Pear, and of a∣bout the bigness of a Walnut, out of the very Body of a stone wherein I suspected it to be enclos'd, and which en∣viron'd it on all sides: and this I took not out of a small and loose stone, but a large stone digg'd out to make Sta∣tues

of. And I remember that one of those that wrought upon it told me, that in fashioning it into Satues they found some more Minerals in the same parcel of stone, which were also presented me. To which I shall adde, that an ingenious Statuary having in another place taken much pains to saw asunder a very large stone, when he came to the midst of it, found he could saw on no further, and the stone being afterwards broken, he perceiv'd that that which so obstinately resisted his Saws was a round Marchasite, which he brought to me, as a Lover of such Curiosities. But I made him for my further satisfaction bring me also that part of the stone wherein the Marcha∣site stuck, and by comparing them together discern'd that as much of the stone as was contiguous to the Marchasite had a kind of rust about it, and fitted the Marchasite so close, as if either the Marchasite had been formerly liquid, and had afterwards been as it were moulded in that Re∣ceptacle, or the stone had been formerly of some soft or fluid matter, which did exactly accommodate it self to the shape of the other Body; or else, as if both the matter of the stone and that of the Marchasite had been at once fluid Bodies, but had each of them preserv'd its own surface di∣stinct (according to what we formerly noted of differing fluids) till one of them (probably the Marchasite) first growing hard, the other, as being yet of a more yielding consistence, accommodated it self to the harder's figure.

But the most eminent Instances to declare how much the Fluidity and Firmness of Bodies depend upon the contri∣vance and Texture of their parts, are afforded us by those waters which being permitted to rest a while do spontane∣ously cease to be fluid and coagulate into stone it self. There was lately an Ingenious Man, who going to visit some Leaden Mines wherein he had a share, found in the Moun∣tain in whose Entrals they were hid a Cave, from whose arched Roof there drop'd down a petrescent Liquor,

which oft-times before it could fall to the ground congeal'd, and by apposition of like matter increas'd so much that they hung from the Roof like Ice-icles in a frosty night from the sides of a House; and of these he gather'd and brought me diverse, which are perfect stones hard and brittle, and of eight or ten inches long, and proportionably thick. Another ingenious friend of mine being lately in France in the C••ve so famous for petrifying Liquor to be there seen, observing some drops of water to congeal into stone whilst he stood by, took them away with him, and sent them me in a Letter. Nay, we shall scarce deny that an external a∣gent of almost insensible bulk may turn animal Bodies into stony ones, by introducing a new texture into their parts, if we will with some modern Writers believe Aventinus, who in his Bavarian History has recorded, that at a time and place by him specified, above forty Country-men, as also some Milk-maids with their Cows kill'd upon an Earth∣quake, had their Bodies by a terrene Spirit turned into statues, which he sayes were seen by the Chancellour of Austria and himself. And some relations of this Nature we meet with in other Authors, which, if they be allowed of, seem much to confirm our Doctrine; for in these strange petrifications, the hardning of the Bodies seems to be ef∣fected principally, if not only, as in the induration of the fluid substances of an Egg into a Chick, by altering the disposition of their parts, since the petrifying wind or steam cannot be suppos'd to have any such considerable (perhaps not any sensible) propo••tion as to bulk to the body chang'd by it, as to be thought to effect this change principally as an Ingredient.

Adde we to all these things, that Pamphilio Piacentino is by an other Author quoted for writing an unparrel'd Story, which because written in Italian, I sh••ll English the sub∣stance of it, which is this: That a Woman in Venice, after having eaten an Apple, was t••ken with hideous tortures,

and in the space of twenty four hours dying, was turned into exceeding hard stone, and this was judged to be the effect of the poyson'd Apple she had eaten. Which narra∣tive, if we may believe it as confidently as the famous Al∣leger of it Pamphilio appears to do, would seem to argue, that even to the wonderful induration of Bodies there is sometimes no other principle requisite than what may re∣sult from the lucky mixture of the parts of several Bodies. And lest we should seem to build altogether upon the Ob∣servations of others, which cannot by us be now brought to strict examination, we will have recourse to a pr••cticable Experiment of our own trying, which though we have else∣where mention'd, we shall not scruple here to repeat, be∣cause we there omitted to speak of that Circumstance of it, which is the most pertinent to our present design.

Take then two Ounces of Quick-silver, two Ounces and a half of the best Verdigreese, about half an Ounce or an Ounce of common Salt, a pint or pound of White-wine-Vinegar, and as much fair water, mingle the Verdigreese, Quick-silver, and the Salt very well, and put the mixture with a little of the Vinegar and water into a new Frying-Pan, (I try'd it in a new Earthen Vessel, but without good success) in which fry it over the fire for diverse hours, keep∣ing it continually stir'd, and putting in more Vinegar and water from time to time, as that already put in consumes away; then take out the mixture, and in several clean wa∣ters wash it carefully from the adhering Salts; then dry away all the Aqueous moisture with a clean linnen Clo••h, and you shall have a bright Amalgama almost like Quick-silver. Now that which is remarkable and to our present purpose in this Experiment is, that though this dry'd mix∣ture be a good while after it is perfectly cold not only so••t, but so neer to fluid, that I have cast it into moulds and mad•• imbost Images of it, (when it has been dexterously made, but scarce otherwise;) I have found, that by laying i•• 〈◊〉〈◊〉

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hours in the air, which seem'd less cold than it self, it has acquir'd such a hardness, that being thrown against the floor it would rebound, and was brittle like over-harden'd Steel. And yet in this Example the induration of the Amalgam appears not to proceed from an innate and in∣ward principle, but from the new Texture resulting from the coalition of the mingled Ingredients that make up the Amalgam, whose parts being variously moved, partly by the fire (and perhaps too by the Salts) and partly by the native propensity to motion of the Mercurial Corpuscles, were by little and little, or by degrees, so dispos'd, that whereas before touching one another but loosly, it was easie to thrust some of them towards the middle of the bo∣dy without stirring much of the Mass (as to sense) by this change of Texture the particles are brought to touch one another more closely and in greater portions of their surfaces, and to be so complicated, intangled, or otherwise connected among themselves, that you cannot endeavour to thrust one of them out of its place, but that its motion shall be resisted by many others, to whom it is so fasten'd, that you cannot move one part of the Mass without either moving the whole with it, or manifestly breaking it off from the whole, and thereby destroying the continuity and unity of the Body.

Now whereas in setting down this Experiment, we spoke as if several Ingredients did concur to constitute the soft Mass, which afterwards grew so hard, we might very safe∣ly do so, since the Quicksilver was not so barely chang'd in Texture as that formerly said to have been coagulated by the meer fume of Lead, but conceal'd in its self a great number of metalline Corpuscles besides others, as we made appear by separating from the Amalgam, meerly by the force of fire, a pretty quantity of true and perfect Copper. That the Salts also both were Ingredients (though in small proportion) of the Mass, and might have some

operation upon the other particles, we may render pro∣bable by this, that having purposely expos'd some of this Mass for a pretty while to a moist Air, we found, as we look'd for, that the formerly invisible particles of Salt, that had so insinuated themselves into the Amalgam, that all the water wherein it was wash'd did not separate them from it, had so wrought upon the metalline particles that were most outward, that they had in many parts of the surface of the Mass turned themselves with it into a kind of Verdigreese, which seemed almost to hide the surface of the Concretion. And that in the more in∣ward parts of a much harder Body than our yielding Amalgam, where Cuprious particles abound, saline Cor∣puscles may have a great operation, may appear by certain sorts of Minerals to be found in some parts of England and elsewhere under the form of stones, of which they make Vitriol; for these abounding with vitriolate, that is, both saline and metalline particles, will, after they are taken out of the ground and laid in the open air, by the working of the inward Salt, some sooner and some later, swell and burst asunder, which could hardly come to pass without a great change made in the internal disposition of the parts, of such stony Concretions. And I remember, that having l••id a mineral of Kin to these stones a while in the air, though but in a Chamber, I found its surface powder'd with little grains of Vitriol, as both their Colour and their Taste inform'd me.

Now whether or no we suppose that the fire did put the parts of the Amalgama into any lasting Agitation, yet the Mass being almost fluid after it was taken from the fire, its parts may according to our notion of Fluidity be well sup∣pos'd to have some kind of motion among themselves; and it will not be deni'd, that the fire might concur with oth••r things to make that motion convenient to cause the parts to fasten themselves to one another: For that ••he motion

wherein a soft and almost fluid Body is once put may pos∣sibly tend to harden it long after that motion seems to be extinct, may be made probable by what has been affirm'd to me by eminent and experienced Masons, namely that the best sort of Lime made into Mortar will not have attain'd its utmost compactness till twenty five or thirty years (per∣haps not till three or fourscore) after it has been imploy'd in Building; and this is given me as one of the Reasons, why in the demolishing of antient Fabricks, it is sometimes more easie to break the stone than the Mortar.

And lastly, that we also made mention of the Texture resulting from the mingled Ingredients of our Amalgam, we might justifie by saying, that having changed the pro∣portion of the Quick-silver to the Verdigreese, we found that the Amalgam coagulated much more slowly, and when it was coagulated, was much less hard than when one used the quantities above specify'd.

Here I should put a period for the present to this Dis∣course, but that having in a late Writer met with a nota∣ble Observation of the natural Induration of a soft Body, I think it worthy to be here annex'd, partly, because the French Book is not common, no more than the Observa∣tion; and partly, that by conferring together this natu∣ral Induration with that Artificial one freshly mention'd, it may the better appear how Nature and Art have some∣times resembling operations in rendring Bodies solid. My Author then (by name Pierre Pelleprat) being not long since sent with some other Jesuites upon the laudable errand of Preaching the Gospel to the Indians of the Southern Ame∣rica,* 1.15 has among other things this passage in the short Re∣lation he makes of the American Continent. There is (says he) one thing worthy of Observation neer the mouth of this great river (he speaks of that of the Amazons) which

is, That men find there a kind of green Clay that is soft as long as 'tis in the water, so that one may print on it all kind of Figures, and give it what shape one pleases; but when it is expos'd to the Air, it hardens to that degree that Diamonds are not much harder than the stones it af∣fords — I have (adds he) seen Hatchets made of this Clay, which the Savages employ'd to cut Wood with, when they had not the use of ours, &c.

And now at last, I see 'tis time to put a period to a discourse, that has been unawares lengthned far too much already: But yet I think you will easily pardon me, if I conclude it not abruptly; but with the recital of an Ex∣periment, which having had the honour to be seen, as to the main part of it, by an illustrious meeting of Curious Men; their having been pleas'd to speak very advantagi∣ously of it to others, excited a curiosity among them, to know by what artifice, effects that were so uncommon, had been produc'd. The Scope therefore, and the man∣ner of making the Experiment, were in short as fol∣lows.

Being desirous to shew how much Fluidity and Firm∣ness may depend upon the Texture and upon the Motion or Rest of the insensible parts of Bodies, I first make with good Spirit of Vinegar, a Solution of Coral so strong, that when 'tis filtrated and cool'd, it will commonly, after some time, begin to have a kind of Sediment at the bot∣tom; the clear Liquor I gently pour off, when the Expe∣riment is to be made, and to this I put a convenient pro∣portion of very well dephlegm'd Spirit of Wine, which if it be pour'd on very slowly and warily, may be made for a pretty while to swim upon it in the form of a di∣stinct Liquor: but if by a few shakes I mingle them to∣gether, they will presently unite into a Concretion, of which when the Experiment succeed very well (as it did when I shew'd it to the above-mention'd Assembly) not

one drop will fall to the ground, upon turning up the wide mouth Glass it should be made in, and holding it with the mouth directly downwards.

And this so hastily produc'd consistence may be dura∣ble enough, if it be carefully lookt to: But to dispatch the whole Experiment in a short time, I take a little strong Spirit of Nitre (which perhaps is not needful if good Aqua Fortis be at hand) and putting about an equal, or other convenient quantity of it to this Mixture, I nimbly stir it and the Spirit together: whereupon the Whole is reduc'd in a very few minutes to a transparent Liquor.

N. B. Though I have divers times made and shewn this Experiment, yet there are so many Circumstances requisite to make the first part of it succeed very well (for to make it succeed in some measure is not so difficult) that the event has sometimes deceiv'd me, in spite of the several Tryals I have made. Wherefore 'twill not be amiss to intimate.

First, That one of the first times, if not the first, I made such an odd Concretion, was, with the Solution not made with Spirit of Vinegar, but with Spirit of Verdigrease: (which I commonly distil without additament) though afterwards I was invited to prefer strong Spirit of Vine∣gar, which was the Liquor wherewith the recited Experi∣ment was exhibited.

Secondly, That it often happens that if the Solution of Coral (which is not the only body wherewith I have made such Tryals with indifferent good success) be not sufficiently strong and impregnated) with Saline parts, or the Spirit of Wine be not sufficiently rectify'd, the shaking of the two Liquors will not change the consistence of the whole mixture, but leaves some part of it fluid, or else the Concretion will not begin presently to be made, but require to be waited for a while.

Thirdly, That I once at least (if not oftner) observ'd,

that when by mingling the two Liquors and shaking them in a narrow mouth'd Glass whose Orifice was stopt, they would not concoagulate (as it was confidently expected they should) yet by trying the Experiment in a wide mouth Glass to which the Air had free access, it succeeded to my content.

Fourthly, That in the Reduction of the Concretion to a fluid Body, 'tis not proper to employ in stirring it a Knife or any other Metalline Body except it be of Gold; but rather some Stick of Glass, or at least some clean Stick of Wood, lest the Menstruum should corrode it, and thereby spoil, or at least blemish the Experiment.

Fifthly, That the proportion betwixt the Coralline So∣lution and the Spirit of Wine depends so much upon the strength of the former Liquor, and the dephlegmedness of the latter, that 'tis scarce possible to determine generally and exactly what quantity of each ought to be taken; and therefore a Tryal or two made with a little of the par∣ticular Solution you intend to employ (for some Solutions require more, others less Spirit of Wine to concoagulate adequately with them) will better direct you what pro∣portion of Spirit will sute that particular parcel of Liquor then any general Rule I can propose.

I know I might here, and perhaps it may be expected that I should, take an occasion to treat also of Hardness, Softness, Brittleness, Toughness, Stiffness, and those other qualities that are of kin to Fluidity and Firmness; but though I confess, I once had thoughts of writing a kind of History of more Qualities than those, yet remembring that wise Counsel given us by one of the Antients, Noscenda est mensura sui, I am now very well content, after having alrea∣dy tir'd my self and I fear you, to recommend so useful but difficult a work to Persons more able and more at leisure than I find my self to go through with so great an under∣taking; contenting my self at present, to have attempted

in what has been delivered concerning a couple qualities of such extent, that every sensibly big Body in the Uni∣verse seems indow'd with one or other of them (I mean concerning Fluidity and Firmness) the explicating of Qua∣lities somewhat more intelligibly than is wont to be done in the Peripatetick Schools, and to have open'd a way (which I hope many will tread) of applying Chymical Ob∣servations and Experiments to the deduction of those effects of Qualities from such general and obvious affections of matter; as Bigness, Motion, and Figure, which even the Hermetical Writers have hitherto contented themselves to refer to Salt, Sulphur, Mercury, and the like: the Chymi∣cal notion of which (three Principles) though of very good use in some other (especially of the more practical) parts of Physiology, seems not as yet to have brought any great light to such matters as we have been treating of, having been hitherto directed not so much to the indaga∣tion of Causes, as to the production of Effects.

The End of the Notes touching Fluidity and Firmness.

FINIS.

Notes

• * 1.1

  Much more considerable In∣stances of this nature may be met with in the Author's New Physico Mechanical Experi∣ments.
• * 1.2

  This Way the Au∣thor afterwards Pub••ished in ano∣ther Book.
• * 1.3

  Hydrograph. Du P. G. Fournier, Lib. 2. Cap. 6.
• * 1.4

  This Phaenome∣non is partly describ'd at large in one of the Authors Physico-Me∣chanical Experiments.
• * 1.5

  Helmont de Febr. cap. 14.
• * 1.6

  Hist. Moral. Cap. 5.
• * 1.7

  Histo. Nat. & Med. Brasil. l. 4. c. 1.
• * 1.8

  Gulielm. Piso, & Author Gal∣lic. ubi supra.
• * 1.9

  Beguin. Tyrocin. Chym. Lib. 2^do Cap. 10.
• * 1.10

  Lib. 4^o. Anno Do∣mini, 1624.
• * 1.11

  Hydrograph. de P. Fournier. Lib. 4. Cap. 27.
• * 1.12

  Lib. 4. Cap. 68.
• * 1.13

  Gassend. in vita Piereskii, lib. 1.
• * 1.14

  In some of the Authors Papers about the Ori∣gine of Mine∣rals.
• * 1.15

  Relation des Mes∣sions des P.P.J.J. secon. part, cap. 1.