Experimental notes of the mechanical origine or production of fixtness.

CHAP. II. (Book 2)

AND first, in some cases it may conduce to Fixation, that, either by an additament, or by the operati∣on of the fire, the parts of a body be brought to touch each other in large portions of their surfaces. For, that from such a contact there will follow such a mutual cohesion, as will at least indispose the touching corpu∣scles to suffer a total divulsion, may appear probable from what we late∣ly noted of the cohesion of pieces of marble and glass, and from some o∣ther Phaenomena belonging to the Hi∣story of Firmness, from which we may properly enough borrow some instances, as least for illustration, in the Doctrine of Fixtness, in regard that usually, though not always,

the same things that make a body Firm, give it some degree of Fixity, by keeping it from being dissipated by the wonted degrees of Heat, and Agitation it meets with in the Air. But to return to the contact we were speaking of, I think it not impossible, (though you may perhaps think it strange,) that the bare operation of the Fire may, in some cases, procure a Cohesion among the particles, (and consequently make them more Fixt,) as well as in others disjoyn them, and thereby make them more Volatile. For, as in some bodies, the figures and sizes of the corpuscles may be such, that the action of the fire may rub or tear off the little beards or hooks, or other particles that intangle them, and by that means make it more easie for the corpuscles to be disingaged and fly upwards; so in other bodies, the size and shape of the corpuscles may be such, that the agitation, cau∣sed by the fire, may rub them one against the other, so as by mutual at∣trition to grind, as 'twere, their

surfaces, and make them so broad and smooth, if not also so flat, as that the contact of the corpuscles shall come to be made according to a large portion of their superficies, from whence will naturally follow a firm Cohesion. Which I shall illustrate by what we may observe among those that grind glasses for Telescopes and Microscopes. For, these Artificers, by long rubbing a piece of glass a∣gainst a metalline Dish or concave Vessel, do by this attrition at length bring the two bodies to touch one another in so many parts of their congruous surfaces, that they will stick firmly to one another, so as sometimes to oblige the Work-man to use violence to disjoyn them. And this instance (which is not the sole I could alleage) may suffice to shew, how a Cohesion of corpuscles may be produced by the mutual ad∣aptation of their congruous surfa∣ces. And if two grosser corpuscles, or a greater number of smaller, be thus brought to stick together, you will

easily believe, their Aggregate will prove too heavy or unwieldy for a∣volation. And to shew, that the fire may effect a laevigation in the surfa∣ces of some corpuscles, I have some∣times caused Minium, and some o∣ther calces, that I judged convenient, to be melted for a competent time, in a vehement fire conveniently ad∣ministred; whereby, according to expectation, that which was before a dull and incoherent powder, was reduced into much grosser corpuscles, multitudes of whose grains appea∣red smooth, glittering, and almost specular, like those of fine litharge of gold; and the masses that these grains composed, were usually solid enough and of difficult fusion. And when we make glass of Lead per se, (which I elsewhere teach you how to doe,) 'tis plain, that the particles of the Lead are reduced to a great smoothness; since, wheresoever you break the glass, the surfaces, produ∣ced at the crack, will not be jagged, but smooth, and considerably specu∣lar.

Nor do I think it impossible, that, even when the fire does not make any great attrition of the Cor∣puscles of the body to be fixt, it may yet occasion their sticking together, because by long tumbling them up and down in various manners, it may at length, after multitudes of revo∣lutions and differing occursions, bring those of their surfaces together, which, by reason of their breadth, smoothness, or congruity of figure, are fit for mutual cohesion; and when once they come to stick, there is no necessity, that the same causes, that were able to make them pass by one another, when their contact was but according to an inconsiderable part of their surfaces, should have the same effect now, when their con∣tact is full; though perhaps, if the degree of fire were much increased, a more vehement agitation would surmount this cohesion, and dissipate again these clusters of coalescent cor∣puscles.

These conjectures will perhaps ap∣pear

less extravagant, if you consider what happens in the preparation of Quick-silver praecipitated per se. For there, running Mercury, being put into a conveniently shaped Glass, is exposed to a moderate fire for a con∣siderable time: (For I have some∣times found six or seven weeks to be too short a one.) In this degree of fire the parts are variously tumbled, and made many of them to ascend, till convening into drops on the sides of the glass, their weight carries them down again; but at length, after many mutual occursions, if not also attritions, some of the parts begin to stick together in the form of a red powder, and then more and more Mercurial particles are fastened to it, till at length all, or by much the greater part of the Mercury, is re∣duced into the like Praecipitate, which, by this cohesion of the parts, being grown more fixt, will not with the same degree of Heat be made to rise and circulate, as the Mercury would before; and yet, as I elsewhere note,

I have found by trial, that, with a greater and competent degree of heat, this Praecipitate per se, would, without the help of any volatilizing additament, be easily reduced into running Mercury again. Chymists and Physicians, who agree in suppo∣sing this Praecipitate to be made with∣out any additament, will perchance scarce be able to give a more likely account of the consistency and de∣gree of Fixity that is obtained in the Mercury; in which, since no bo∣dy is added to it, there appears not to be wrought any but a Mechanical change. And though, I confess, I have not been without suspicions, that in Philosophical strictness this Praecipitate may not be made per se, but that some penetrating igneous particles, especially saline, may have associated themselves with the Mer∣curial Corpuscles; yet even upon this supposition it may be said, that these particles contribute to the ef∣fect that is produced, but by facilita∣ting or procuring, by their oppor∣tune

Interposition, the mutual Cohe∣sion of Corpuscles that would not otherwise stick to one another.

Perhaps it will not be altogether impertinent to add, on this occasion, that, as for the generality of Chymists, as well others as Helmontians, that as∣sert the Transmutation of all metalls into Gold by the Philosopher's Stone, me thinks, they may grant it to be pro∣bable, that a new and fit Contexture of the parts of a volatile body may, especially by procuring a full contact among them, very much contribute to make it highly fixt. For, to omit what is related by less credible Au∣thours, 'tis averred, upon his own trial, by Helmont, who pretended not to the Elixir, that a grain of the pow∣der, that was given him, transmuted a pound (if I mis-remember not) of running Mercury; where the pro∣portion of the Elixir to the Mercury was so inconsiderable, that it cannot reasonably be supposed, that every Corpuscle of the Quick-silver, that before was volatile, was made ex∣treamly

fixt meerly by its Coalition with a particle of the powder, since, to make one grain suffice for this Coalition, the parts it must be divi∣ded into must be scarce conceivably minute, and therefore each single part not likely to be fixt it self, or at least more likely to be carried up by the vehemently agitated Mercury, than to restrain that from avolation; whereas, if we suppose the Elixir to have made such a commotion among the corpuscles of the Mercury, as (having made them perhaps somewhat change their figure, and expelled some inconvenient particles,) to bring them to stick to one another, according to very great portions of their surfaces, and intangle one another, it will not be disagreeable to the Mechanical Doctrine of Fixity, that the Mercury should, endure the fire as well as Gold, on the score of its new Tex∣ture, which, supposing the story true, appears to have been introdu∣ced, by the new colour, specifick gravity, Indissolubleness in Aqua

fortis, and other Qualities wherein Gold differs from Mercury, espe∣cially Malleableness, which, accor∣ding to our Notes about that Quali∣ty, usually requires that the parts, from whose union it results, be ei∣ther hooked, branched, or other∣wise adapted and fitted to make them take fast hold of one another, or stick close to one another. And since, in the whole mass of the factitious Gold, all save one grain must be ma∣terially the same body, which, before the projection was made, was Quick-silver, we may see how great a pro∣portion of volatile matter may, by an inconsiderable quantity of fixing additament, acquire such a new Dis∣position of its parts, as to become most fixt. And however, this In∣stance will agree much better with the Mechanical Doctrine about Fixi∣ty, than with that vulgar Opinion of the Chymists, (wherewith 'twill not at all comply,) That if, in a mix∣ture, the volatile part do much ex∣ceed the fixt, it will carry up that,

or at least a good portion thereof, with it; and on the contrary. But though this Rule holds in many cases, where there is no peculiar indispositi∣on to the effect that is aimed at; yet if the Mechanical affections of the bodies be ill suited to such a purpose, our Philosophical Experiment mani∣festly proves, that the Rule will not hold, since so great a multitude of grains of Mercury, in stead of carry∣ing up with them one grain of the Elixir, are detained by it in the stron∣gest fire. And thus much for the first way of fixing Volatile Bodies.