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 PREFACE, Giving an account of the two following Treatises, and Proposing the Desirableness of a good Intelligence betwixt the Corpuscularian Philosophers and the Chy∣mists.

THere are many Learned Men, who being ac∣quainted with Chymistry but by report, have from the Illiterateness, the Arrogance and the Impostures of too many of those that pretend skill in it, taken occasion to entertain so ill an opinion as well of the Art as of those that pro∣fess it, that they are apt to repine when they see any Person capable of succeeding in the study of solid Philosophy, addict himself to an Art they judge so much below a Philosopher, and so unserviceable to him: Nay, there are some that are trou∣bled when they see a Man acquainted with other Learning countenance by his Example sooty Empiricks, and a study which they scarce think fit for any but such as are unfit for the rational and useful parts of Physiology. I now take notice of these things, because they gave occasion to the two following Treatises. For perceiving divers years ago, that some Learn∣ed Men of the temper above describ'd thought it strange (if not amiss also) that one of whose studies they were pleas'd to have too favourable an Expectation, should spend upon Chymical tryals (to which I then happen'd to be invited by the opportu∣nity of some Furnaces and some leisure) much of those En∣deavours

which they seem'd to think might be far more use∣fully employ'd than upon such an empty and deceitful study; perceiving this, I say, I thought it not amiss to endeavour to manifest, that without seeking after the Elixir that Alchymists generally hope and toyl for, (but which they that knew me knew to be not at all in my aim) I did not in the Prosecution of Chy∣mical tryals do any thing either without an end, or unsuitable to the Design I had of attempting to promote Mens Knowledge of the works of Nature, as well as their Power over them. In order to this, I did not think it enough to shew, that by an In∣sight into Chymistry one may be enabl'd to make some Meliorations (I speak not of Transmuta∣tions) of Mineral and Metalline Bodies, and many excellent Medicines for the Health of Men, besides divers other Preparations of good use in particular Trades, and in several Occurren••es of Humane Life; I did not, I say, think it enough to do this, because that though this might suffice to evince that a rational man might without losing his time em∣ploy some of it to understand and promote Chymistry; yet this would scarce suffice to manifest it to be useful to Philoso∣phy. And therefore there seem'd requisite some specimens, which might shew that Chymical Experiments might be very assistant even to the speculative Naturalist in his Contempla∣tions and Enquiries.

But against my attempting any thing of this Nature, three Difficulties oppos'd themselves. The first was the want of Leisure, in regard I was already pre-engag'd to write of other Subjects, and to prosecute some Experiments, whose event I was concern'd to know. Another Impediment was, that for other Reasons elsewhere mention'd, and chiefly to keep my Judgment as unprepossess'd as might be with any of the Modern Theories of Philosophy, till I were provided of Experiments to help me to judge of them, I had purposely refrain'd from acquainting my self throughly with the intire System of either

the Atomical, or the Cartesian, or any other whether New or Reviv'd Philosophy; and therefore I could scarce be fit to shew how Chymical Experiments might illustrate their Do∣ctrines. And thirdly, some of those Learned Men for whom I was to write, more favouring the Epicurean, and others (though but a few) being more inclinable to the Cartesian opi∣nions, it seem'd very difficult to gratifie by the same Compo∣sures Persons of differing Perswasions.

But as to the first of these Discouragements, since my Pre∣engagements to other Themes were not unknown to those for whom I was to write, it might reasonably be presum'd they would over-look such unaccurateness as should appear imputable to haste: And besides, some such Subject might be chosen to write of, as would conveniently admit Enlargements and Additions, ac∣cording as my leisure should afterwards serve me to annex them

On occasion of the second Impediment, I remember'd, that having divers years before read the Lives of the Atomical, a∣mong other Philosophers, in Diogenes Laertius, and having sometimes occasionally heard mention made of divers Epicu∣rean and Cartesian Notions, and having hence fram'd to my self some general, though but imperfect, Idea of the way of Phi∣losophizing my friends esteem'd; I thought I might without a more particular and explicit Enquiry into it, say something to illustrate some Notions of it, by making choice of such as, being of the more simple and obvious, did not require skill in the more mysterious points of the Hypothesis they belong'd to.

And as for the last of the three Discouragements above men∣tion'd, I consider'd, that the Atomical & Cartesian Hypotheses, though they differ'd in some material points from one another, yet in opposition to the Peripatetick and other vulgar Doctrines they might be look'd upon as one Philosophy: For they agree with one another, and differ from the Schools in this grand & fun∣damental point, that not only they take care to explicate things intelligibly; but that whereas those other Philosophers give only a general and superficial account of the Phaenomena of Nature

from certain substantial Forms, which the most ingenious a∣mong themselves confess to be Incomprehensible, and certain real Qualities, which knowing men of other Perswasions think to be likewise Vnintelligible; both the Cartesians and the Ato∣mists explicate the same Phaenomena by little Bodies variously figur'd and mov'd. I know that these two Sects of Modern Naturalists disagree about the Notion of Body in general, and consequently about the Possibility of a true Vacuum, as also about the Origine of Motion, the indefinite Divisibleness of Matter, and some other points of less Importance than these: But in regard that some of them seem to be rather Metaphysical than Physiological Notions, and that some others seem rather to be requisite to the Explication of the first Origine of the Vniverse, than of the Phaenomena of it in the state wherein we now find it; in regard of these, I say, and some other Considerations, and especially for this Reason, That both parties agree in dedu∣cing all the Phaenomena of Nature from Matter and local Mo∣tion; I esteem'd that notwithstanding these things wherein the Atomists and the Cartesians differ'd, they might be thought to agree in the main, and their Hypotheses might by a Person of a reconciling Disposition be look'd on as, upon the matter, one Philosophy. Which because it explicates things by Corpuscles, or minute Bodie•• may (not very unfitly) be call'd Corpuscular; though I sometimes style it the Phoenician Philosophy, because some ancient Writers inform us, that not only before Epicurus and Democritus, but ev'n before Leucippus taught in Greece, a Phoenician Naturalist was wont to give an account of the Phaenomena of Nature by the Motion and other Affections of the minute Particles of Matter. Which because they are obvi∣ous and very powerful in Mechanical Engines, I sometimes also term it the Mechanical Hypothesis or Philosophy.

By such considerations then, and by this occasion, I was invi∣ted to try whether without pretending to determine the above-mention'd controverted points, I could by the help of the Cor∣puscular Philosophy, in the sense newly given of that Appellati∣on,

associated with Chymical Experiments, explicate some particular Subjects more intelligibly than they are wont to be accounted for, either by the Schools or the Chymists. And how∣••ver since the vulgar Philosophy is yet so vulgar, that it is still in great request with the Generality of Scholars; and since the Mechanical Philosophers have brought so few Experiments to verifie their Assertions, and the Chymists are thought to have brought so many on the behalf of theirs, that of those that have quitted the unsatisfactory Philosophy of the Schools, the greater Number dazl'd as it were by the Experiments of Spagyrists, have imbrac'd their Doctrines instead of those they deserted; For these Reasons, I say, I hop'd I might at least do no unseaso∣nable piece of service to the Corpuscular Philosophers, by illu∣strating some of their Notions with sensible Experiments, and manifesting that the things by me treated of, may be at least plausibly explicated without having recourse to inexplicable forms, real Qualities, the four Peripatetick Elements, or so much as the three Chymical Principles.

Being once resolv'd to write some such Specimina as I for∣merly judg'd requisite, I soon bethought my self of the Experi∣ment hereafter deliver'd concerning Salt-Petre, divers of whose Phaenomena I did also, as time would permit, cast into one of the Essays I was then engag'd to write to a Friend. And having dispatch'd that little Treatise, it found so favourable a Reception among those Learned Men into whose hands it came, that I was much encourag'd to illustrate some more of the Doctrines of the Corpuscular Philsosophy, by some of the Ex∣periments wherewith my Furnaces had suppli••d me; which al∣so as occasion serv'd I did, partly by writing some Physico-Chy∣mical Treatises, and partly by making such large Notes on the Essay concerning Salt-Petre, as might plentifully contribute to the History of Qualities, of which I had sometimes thoughts. And this continu'd, till in the year before the last, the publick Confusions in this (then un∣happy) Kingdom reducing me to quit my former Design, toge∣ther

with the place where my Furnaces, my Books, and my o∣ther Accommodations were, I fell afterwards upon the making of Pneumatical tryals, whereof I lately ventur'd to give the Publick an account in a Book of New Experiments Physo-mechanical about the Air.

I should not trouble the Reader with so prolix a Preface to such small Treatises as those whereto this is prefix'd, but for these two Reasons. The one, that I hope the fore-going Narra∣tive will make me be the more favourably judg'd by the Philo∣sophers I desire to serve, if sometimes I write less skilfully of their Opinions than perhaps I should have done had I allow'd my self to search into them: And the other, that I am earnestly sol∣licited to publish some other Tracts, tending to the same purpose that these do; to which also should I ever be induc'd, by the Re∣ception these may meet with, to trouble the World with them, the same Preface as it is now penn'd may serve for an Introdu∣ction. I had almost forgot to take notice, That whereas at the end of the Essay concerning Salt-Petre I mention'd a then newly-publish'd Treatise of the laborious Glauber's, which I had not then perus'd, I found it to contain some Observations concern∣ing the History of Salt-Petre, which, if they be true, are conside∣rable enough: I must again recōmend the examination of them to the Readers Curiosity, having been hinder'd by divers Avo∣cations from saving him that labour my self. And whereas also some years after I was inform'd of another little Book he had put out since the former, wherein he teaches us a way of puri∣fying Salt-Petre, to make a Conjunction of the spirituous and fixter parts of it, and then to suffer the Mixture to evaporate and so crystallize into Nitre; This would I confess have made me apprehensive of passing for a Plagiary with those that did not know me, but that it was easie for me to clear my self by the Testimony of very Learned Men, who had some years before perus'd my Treatise, and especially of one person, (well known by his Writings) who was pleas'd to like it so well, as to desire he might translate it, and

had accordingly long before turn'd it into very elegant Latin. I might perhaps venture to adde, that though I could not justifie my self by so convincing a proof of my Innocence, yet he that shall take the pains to consider that I could not borrow of Glau∣ber the various Phaenomena I have particularly set down, and much less the Reflections on them, & shall compare in what dif∣fering manners, and to what differing purposes, we two propose the making of Salt-Petre out of its own Spirit, and fixt Salt (He but prescribing as a bare Chymical Purification of Nitre, what I teach as a Philosophical Redintegration of it;) He, I say, who shall compare these things together, will perchance think, that I was as likely to find this last nam'd Experiment as another. Which things I say not, as if I scrupl'd to make use of the indu∣strious Glauber's or any other mans Experiments, especially when I borrow not with them any of the Doctrines I build on them; but because since I neither did nor could take any notice of Glauber's Book in mine, I judg'd it requisite to say something to prevent my being thought to have unthankfully taken one of the chief Passages of my Discourse from a Book to which I was utterly a stranger.

The Reasons of my thus consenting to publish the following History of Fluidity and Firmness, without the rest of those An∣notations which I writ upon the same Essay touching Salt-Petre, are partly, that these are my recentest Composures of this Na∣ture, (having been writen but the last year save one) and were set down when I allow'd my self to be less unacquainted with Writers addicted to the modern Philosophy; partly also, be∣cause the considerableness of the Subject invited me to make these Annotations much more copious, and somewhat less unac∣curate, than my Notes upon almost any other part of the Essay; & partly, (and indeed principally) because mention being some∣times made of this History in my freshly publish'd Physico-Me∣chanical Experiments, both the Printer, and some Learned Gentlemen who were pleas'd to think that Book not unworthy the Translating, have sollicited me to let this Treatise be

annexed to the several Versions they are about of that Pneuma∣tical piece, and to the English Edition of the three fore-going Discourses, which the Printer fears would, without the com∣pany of these or some others, make but too thin a Book.

And I thought fit to premise to this History, the Essay con∣cerning Salt-Petre, not only because it might appear very im∣proper to publish Annotations without the Text it self whereunto they relate; but indeed because I find that there are still many Learned Men, of the same disposition with those I have men∣tion'd in the beginning of this Preface; whence I am invited to divulge this Essay by the same Considerations that at first in∣duc'd me to write it. Especially since I remember not that among the new Philosophers I have met with any one Experi∣ment that does so fairly and sensibly accommodate so many of their Opinions. And indeed I freely confess, that I shall think my self to have done no useless service to the Common-wealth of Learning, if I prove so fortunate, as by these, or any other Writings of mine to the like purpose, to beget a good under∣standing betwixt the Chymists and the Mechanical Philoso∣phers, who have hitherto been too little acquainted with one anothers Learning: There being to this very day a great and almost general Mis-understanding betwixt the Corpuscular Philosophers and the Chymists; most of Those (on the one hand) looking upon the Spagyrists as a company of meer and irrational Operators, whose Experiments may indeed be service∣able to Apothecaries, and perhaps to Physicians, but are useless to a Philosopher that aims at curing no disease but that of Igno∣rance; and most of the Spagyrists (on the other hand) look∣ing upon the Corpuscularians (if I may so call them) as a sort of empty and extravagant Speculators, who pretend to explicate the great Book of Nature, without having so much as look'd upon the chiefest and the difficultest part of it, name∣ly the Phaenomena that Their Art has added to the former Edi∣tion of this vast and obscure Volume. But that some of the principal of the Hermetick Opinions may be more handsomely

accommodated by the notions of the Phoenician Hypotheses, than by the common Philosophy of Elements of substantial forms, (which yet their Writers so frequently allude to and otherwise employ) may appear from hence, that whereas the Schools generally declare the transmutation of one Species into another, and particularly that of baser metals into Gold, to be against Nature, and Physically impossible; the Corpuscular Doctrine rejecting the substantial forms of the Schools, and making Bodies to differ but in the Magnitude, Figure, Mo∣tion or Rest, and Situation of their component particles, which may be almost infinitely varied, seems much more fa∣vourable to the Chymical Doctrine of the possibility of working wonderful changes, and even transmutations in mixt Bodies. And on the other side, there are scarce any Experiments that may better accommodate the Phoenician principles, than those that may be borrowed from the Laboratories of Chymists. For first, Chymistry enabling us to depurate Bodies, and in some measure to analyse them, and take asunder their Heterogeneous parts, in many Chymical Experiments we may better than in others know what manner of Bodies we employ, Art having made them more simple or uncompounded than Nature alone is wont to present them us. And next, many Chymical opera∣tions being performed in close, and yet in transparent vessels, we may better know what concurs to the effects produced, be∣cause adventitious Bodies (or at least all grosser ones) are kept from intruding upon those whose Operations we have a mind to consider. And lastly, the Bodies employ'd by the Chymists being for the most part active ones, the progress of Nature in an Experiment, and the series of successive alterations through which the matter passes from first to last, is wont to be made more nimbly, and consequently becomes the more easie to be taken notice of and comprehended. So that all this considered, I hope it may conduce to the Ad∣vancement of Natural Philosophy, if, as I said, I be so happy as, by any endeavours of mine, to possess both Chymists

and Corpuscularians of the advantages that may redound to each Party by the Confederacy I am mediating between them, and excite them both to enquire more into one anothers Philo∣sophy, by manifesting, that as many Chymical Experiments may be happily explicated by Corpuscularian Notions, so ma∣ny of the Corpuscularian Notions may be commodiously ei∣ther illustrated or confirmed by Chymical Experiments.

Notes

• See the Essay of the Vsefulness of Chy∣mistry in the II. Sect. of the I. Part Of the Vsefulness of E. P.
• Viz. A. D. 1659.