CHAP. IV.

MOst men, when they think at all of the effluvia of bodies and their motions, are wont to think of them as if they were but much finer sorts of Dust, (whose grains, by reason of their smalness, are invisible,) which, by the various agitation of the Air, are Page  28 as 'twere by some faint wind blown against the surfaces of the bodies they chance to meet in their way, and that they are stopped in their progress without penetrating into the interior parts of the bodies they invade. And according to this Notion, 'tis no won∣der, that men should not fancy, that such minute bodies passing, as they sup∣pose, no further than the surfaces of those on which they operate, should have but faint operations upon them.

But we may have other thoughts, if we well consider, that the Corpu∣scles we speak of, are, by their minute∣ness, assisted, and oftentimes by their figure inabled, to pierce into the in∣nermost recesses of the body they invade, and distribute themselves to all, or at least to multitudes of the mi∣nute parts, whereof that body consists. For this being granted, though we suppose each single effluvium or parti∣cle to be very minute; yet, since we may suppose, even solid bodies to be made up of particles that are so too, and the number of invading particles Page  29 to be not much inferior to that of the invaded ones, or at least to be excee∣dingly great, it need not seem incredi∣ble, that a multitude of little Corpu∣scles in motion (whose motion, may, for ought we know, be very swift) should be able to have a considerable operation upon particles either qui∣escent, or that have a motion too slow to be perceptible by sense. Which may perhaps be the better conceived by the help of this gross example:

If you turn an Ant-hill well stoc∣ked with Ants-eggs, upside down, you may sometimes see such a heap of eggs mingled with the loose earth, as a few of those Insects, if they were yoaked together, would not be able at once to draw after them; but if good numbers of them disperse them∣selves and range up and down, and each lay hold of her own egge, and hurry it away, 'tis somewhat surprizing to see (as I have with pleasure done) how quickly the heap of eggs will be displaced, when almost every little egge has Page  30 one of those little Insects to deal with it.

And in those cases, wherein the in∣vading Fluid does not quite disjoin and carry off any great number of the parts of the body it invades, its operation may be illustrated by that of the wind upon a tree in Autumn: for, it finds or makes it self multi∣tudes of passages, for the most part crooked, not onely between the bran∣ches and twigs, but the leaves and fruits, and in its passing from the one side to the other of the tree, it does not onely variously bend the more flexible boughs and twigs, and perhaps make them grate upon one another, but it breaks off some of the stalks of the fruit, and makes them fall to the ground, and withall carries off divers of the leaves, that grew the least firmly on, and in its passage does by its differing parts act upon a multitude of leaves all at once, and variously alters their si∣tuation.

But to come to closer Instances: Page  31 suppose we cast two lumps, the one of Sugar, the other of Amber, into a glass of beer or water, they will both fall presently to the bottom. And though perhaps the Amber may be lighter than the Sugar, (for, I have found a notable difference in the specific gravity of pieces of Amber,) yet the aqueous particles are far from being able to displace the Amber or any sensible part of it, or exercise any visible operation upon it: But the same minute particles of the li∣quor being of a figure that fits them to insinuate themselves every way into the pores of the Sugar, though the lump consisted of very nume∣rous Saccharine Corpuscles, yet the multitude of the aqueous particles, to which they are accessible, is able in no long time to disperse them all, and carrying them along with them∣selves, make the whole lump of Su∣gar in a short time quite disappear.

The point above discoursed of, may be more nimbly exemplified in some Chymical operations, and par∣ticularly Page  32 in this. If, by a due degree of fire, you abstract from running Mercury four or five times its weight of good Oil of Vitriol, there will re∣main at the bottom a dry and brittle substance exceeding white; and, if upon this Heap of Mercurial and Sa∣line bodies, which sometimes may be coherent enough, you pour a good quantity of limpid water, and shake them together, you may see in a trice the multitude of little white grains, that make up the masse, pervaded, and manifestly altered, by the dis∣persed Corpuscles of the water; as will plainly appear by the change of the Calx or Precipitate from a white masse into one of a fine Limon-co∣lour.

But to give instances in Fluid bodies, (which I suppose you will think far the more difficult part of my task,) though you will easily grant, that the flame of Spirit of wine, that will burn all away is but a visible ag∣gregate of such E••luvia swiftly agi∣tated, as without ••y sensible Heat Page  33 would of themselves invisibly exhale away; yet, if you be pleased to hold the blade of a knife, or a thin plate of Copper, but for a very few mi∣nutes, in the flame of pure Spirit of wine, you will quickly be able to discern by the great Heat, that is, the various and vehement agitation of the minute Corpuscles of the me∣tal, what a number of them must have been fiercely agitated by the perva∣sion of the igneous particles, if we suppose, (what is highly probable,) that they did materially penetrate into the innermost parts of the me∣tall; and whether we suppose this or no, it will, by our experiment, appear, that so fluid and yielding a body, as the flame of Spirit of wine, is able, almost in a trice, to act very powerfully upon the hardest me∣talls.

The power of extreamly-minute parts of a fluid body, even when but in a moderate number they are de∣termined to conspire to the same o∣peration, may be estimated by the Page  34 motions of Animals, especially of the larger and more bulky sorts, as Hor∣ses, Bulls, Rhinocerots and Ele∣phants. For, though the animal spirits be minute enough to be in∣visible, and to flow through such tender passages, that prying Anato∣mists have not been able in dissected Nerves to discern so much as the channels through which they pass; yet those Invisible Spirits, conveyed (or impelled) from the Brain to the Nerves, serve to move in various manners the Lims, and even the unwieldy bodies themselves of the greatest Animals, and to carry them on in a progressive motion for many hours together, and perhaps enable them to spring into the Air, and move through it by leaping; though di∣vers of these Animals weigh many hundred, and others several thousand of pounds.

I will not here consider, whether the following Experiment may at all illustrate Motions that are produced by the fluid parts of Animals in some Page  35 of the consistent ones: But I pre∣sume, it may confirm the Observation maintained in this Chapter, if I add, what I have tried of the considerable force of a number of aqueous particles, as flexible and as languid as they are thought to be, insinuating themselves into the pores or Intervals of a rope that was not thick. For in moist weather I sometimes observed, that the aqueous and other humid parti∣cles, swimming in the air, entering the pores of the hemp in great numbers, were able to make it shrink, though a weight of fifty, sixty, or even more pounds of lead were tied at the end to hinder its contraction, as ap∣peared by the weights visibly being raised in wet weather above the place it rested at in dry.

But to return to what I was for∣merly speaking of the Determinati∣on of the motion of Fluids; I shall, on this occasion, observe, that, though the wind or breath, that is blown out at a small crooked pipe of metal or glass, such as Tradesmen for its Page  36 use call a Blow-pipe, seems not to have any great celerity, especially in comparison of that of the parts of flame; and is it self of little force; yet, when by this wind the flame of a Lamp or Candle is directed so as to beat with its point upon a body held at a convenient distance from the side of the flame, the burning fluid, determined, and perhaps excited by this wind, acquires so great a force, that, as we have often tried, it may be made, in a few minutes, to melt not onely the more fusible Metals, but silver, or even copper it self; which yet may be kept for many hours unmelted in a Crucible kept red-hot, or even in the flame of the Lamp or Candle, unassisted by the blast.

And if we can so contrive it, that a flame does not come to invade onely the surface that invests a body, but comes to be intermingled with the smaller (though not the smallest) parts it consists of, as with its filings or its powder; the flame will then have a far more quick and powerfull Page  37 operation than the body exposed to it. This I exemplify (in other Papers) and in this place it may suffice to ob∣serve, that, whereas a pound or two of Tartar may cost you some hours to calcine it to whiteness, if the flame have immediate access onely to the outward parts; you may calcine it in a very small part of that time, if, mixing with its gross powder an equal weight of good Salt-peter, you fire the mixture, and keep it stirring, that the parts of the kindled Nitre may have access at once to very many parts of the Tartar, and have opportunity to calcine them. And by somewhat a like artifice, I else∣where teach, how Nitre it self may without Tartar be speedily reduced to a Calcinatum, not unlike that newly mentioned. But it may be said, that some of the foregoing Instances (for it cannot be truly said of all) may indeed illustrate what we are dis∣coursing of, but will not reach home to our purpose.

I shall therefore consider the Page  38 Load-stone, which you acknowledge to act by the emission of Insensible particles. For, though Iron and Steel be solid and ponderous bodies, and Magnetical effluvia be corpuscles so very minute, that they readily get in at the pores of all kind of bodies, and even of Glass it self; yet these Magnetical effluvia, entring the steel in swarms, do in a trice pervade it, and a multitude even of Them, acting upon the Corpuscles of the metal, do operate so violently on them, that, if the Load-stone be vigorous enough, and well capped, it will attract a no∣table proportion of steel, and sur∣mount the gravity of that solid metal, which I have found to exceed, when the stone has been very good and lit∣tle, above fifty times the weight of the Magnet by whose effluvia it was supported: For, to these I rather a∣scribe Magnetical attraction and sus∣tentation, than to the impulse or pressure of the ambient air, to which many Corpuscularians have recourse; because I have found by trial (which Page  39 I elsewhere relate) that the pressure of the ambient air is not absolutely necessary to Magnetical operations.

I remember, that, to help some friends to conceive, how such ex∣treamly-minute particles as Magne∣tical effluvia, may, by pervading a hard and solid body, such as Iron, put its insensible Corpuscles into motion, and thereby range them in a new manner, I took filings of Steel or I∣ron freshly made, that the Magnetical virtue might not be diminished by any rust, and having laid them in a little heap upon a piece of paper held level, I applied to the lower side of the paper, just beneath the Heap, the pole of a vigorous Load-stone, whose Emissions traversing the paper, and diffusing themselves through the in∣cumbent metall, did in a trice mani∣festly alter the appearance of the Heap; and, though each of the filings might probably contain a multitude of such small Martiall Corpuscles as Steel may be divided into by Oil of Vitriol or Spirit of Salt; yet the Mag∣netical Page  40 effluvia, immediately perva∣ding our metalline heap, did so re∣move a good part of the filings that composed it, as to produce many erected aggregates, each of which consisted of several filings placed one above another, and appearing like little needles, or rather like the ends of needles broken off at some distance from the point. And as these little temporary needles stood all of them erected (though more or less, accor∣ding to their distance from the Pole of the Magnet) upon the flat paper; so they would, without losing their figure or connexion, be made as it were to run to and fro upon the pa∣per, according as the Load-stone, that was held underneath it, was moved this way and that way; and as soon as that was taken quite away, all this little stand of pikes (if I may so call it) would (almost in the twinkling of an eye) relapse into a confused heap of filings.

There are two ways of explicating the turning of Water into Ice; one Page  41 or other of which is approved almost by all the Corpuscularian Philoso∣phers. The first is that of the Car∣tesians, who give an account of Glaci∣ation by the recesse of the less subtile particles of the Etherial matter, without which the finer parts were too small and feeble to keep the Eel∣like particles of water flexible, and in the form of a liquour. The Ato∣mists on the other side ascribe the free∣zing of water to the ingress of mul∣titudes of frigorifick Corpuscles, as they call them, which, entering the water in swarms, and dispersing themselves through it, crowd into the pores, and hinder the wonted mo∣tion of its parts, wedging themselves (if I may so speak) together with them into a compact body. But which soever of these two Hypothe∣ses be pitched upon, the Phaenome∣non it self will afford me a notable Instance to my present purpose. For, the Particles of water, and much more the Corpuscles of cold, are con∣fessed to be singly too small to be Page  42 visible, and their motions are not said to be swift, but may rather be judged to be slow enough; and yet those minute aqueous, or more minute fri∣gorifick particles, because of their number, produce in the glaciation of the liquour so forcible a motion outwards, as to make it break bottles, not onely of glass and earth strongly baked, but, as I have several times tri∣ed, of metal it self, that being full of the liquour were firmly stopped be∣fore the supervening of the Cold. And the expansive endeavour of freezing water is not onely capable of doing this, but of performing so much grea∣ter things, which I elsewhere relate, that my trials have made me some∣times doubt, whether we know any thing in nature, except kindled Gun∣powder, that bulk for bulk moves more forcibly, though the motion seems to be very slow.