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April 10, 2026
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"The old philosophy of the Greeks had, as we have seen, become merged into the doctrine of the iatro-chemists; and this was now to be purified from the theosophical mysticism with which Paracelsus and his followers had enshrouded it. "The ical subtleties of the schoolmen much more," says Boyle, "declare the wit of him that uses them than increase the knowledge or remove the doubts of sober lovers of truth... For in such speculative inquiries where the naked knowledge of the truth is the thing principally aimed at, what does he teach me worth thanks, that does not, if he can, make his notion intelligible to me, but by mystical terms and ambiguous phrases darkens what he should clear up, and makes me add the trouble of guessing at the sense of what he equivocally expresses, to that of learning the truth of what he seems to deliver.""
"He... discovered the dependence of the of a liquid upon , explained the action of the , the effect of the air on the vibration of a pendulum and on the propagation of sound, and made experiments on the nature of , and on the relation of air to and ."
"I have... hinted at the probability that Boyle himself was involved only in a very limited way in 'his' experimental manipulations. The device which became known as the machina Boyleana [air pump] was almost certainly constructed for him by remunerated assistants Ralph Greatorex and Robert Hooke, and even the extent of Boyle's rule in its evolving design remains unclear. The glass J-shaped tube that yielded his law of pressures and volumes was again almost certainly made for him and had to be manipulated by him in collaboration with assistants, if not solely by them. The furnaces in his laboratory, and the alembics in which long-term distillations were performed, were probably tended by assistants."
"He introduced the air-pump into England, and his "pneumatical engine" enabled him to discover many of the fundamental properties of a gas, notably the relation of its volume to pressure."
"The words "element" and "principle" are used by him as equivalent terms, and signify those primitive and simple bodies of which compounds may be said to be composed, and into which these compounds are ultimately resolvable."
"In 1680, Robert Boyle published the Second Part of his Continuation of New Experiments Physico-mechanical, Touching the Spring and Weight of the Air. ...According to Boyle's preface, the experimental work... was mainly done by a remunerated technician... Denis Papin. The air-pump with which the experiments were performed was... of Papin's own design... At least some, and perhaps the greatest part, of the design of the experimental project was also owing to the technician. ...It seems also that the technician was partly, if not mainly, responsible for the composition of the experimental narratives."
"Boyle's early endorsement of philosophical openness was soon compromised by, as he put it, the sordid requirements of trading with those who "need to make pecuniary advantage" of secret knowledge. By 1674 Boyle made no scruples about his distaste for necessary philosophical dealings with the artisan and trading classes."
"The influence of the new spirit... infused into the science by Boyle is seen in the general style of chemical literature at the end of the seventeenth century, when compared with that of the close of the sixteenth. The mysticism and obscurity of the alchemists were no longer tolerated."
"He revived the atomic hypothesis, and explained chemical combination on the basis of affinity."
"Boyle's greatest service to learning consisted in the new spirit he introduced into chemistry. Henceforward chemistry was no longer the mere helpmeet of medicine. She became an independent science, the principles of which were to be ascertained by experiment; a science to be studied with the object of discovering the laws regulating the phenomena with which it is concerned and hence elucidating truth for truth's sake."
"He contended that one of the main objects of the chemist was to ascertain the nature of compounds; and thereby he stimulated the application of analysis to chemistry. Boyle discovered a number of qualitative reactions, and applied them to the detection of substances, either free or in combination."
"He prepared by the distillation of the s of lead and lime; and he isolated methyl alcohol from the products of the of wood."
"Robert Boyle was a younger son of Richard Boyle, first earl of Cork, the next to last of his father's sixteen children, and the youngest surviving son. Boyle's father was... a self-made man... it is probable that his parents were of yeomen stock. Arriving in Dublin from England at age twenty-one... he launched a career whose ambition and acquisitiveness were matched only by its spectacular success. ...All this was not achieved without manking many enemies. In their view, and that of most Irish historians, Boyle was a robber baron of heroic stature, using his position to defraud Irish landowners... of their existing titles and and to pass title to himself at absurdly deflated prices. He then expelled the Irish tenants and replaced them with more pliable and profitable English settlers. ...Boyle was twice imprisoned, and he was obliged to use his considerable connections to obtain a royal pardon for... charges of fraud."
"He was one of the earliest to insist on the necessity of studying the forms of crystals. He saw in their formation proof that the internal motions, configuration, and position of the integral parts are all that is necessary to account for alterations and diversities in outward character."
"In his History of Fluidity he seeks to show that a body seems to be by consisting of corpuscles touching one another only in some parts of their surfaces; whence, by reason of the numerous spaces between them, they easily glide along each other till they meet with some resisting body to whose internal surface they exquisitely accommodate themselves. He considers the requisites of fluidity to be chiefly these: The smallness of the component particles, their determinate figure, the vacant spaces between them, and the fact of their being agitated variously and apart by their own innate motion or by some thinner substance which tosses them about in its passage through them."
"Some of the stock illustrations of our lecture-rooms were of his contrivance. Thus he illustrated the expansive power of freezing water by bursting a plugged gun-barrel filled with water by solidifying the water by means of a mixture of snow and salt a freezing mixture which he first introduced."
"He concludes... that the Paracelsian elements—their "salt," "sulphur," and "mercury"—are not the first and most simple principles of bodies; but that these consist, at most, of concretions of corpuscles or particles more simple than they, and possessing the radical and universal properties of volume, shape, and motion."
"The supremacy of the old philosophy may be said to have been first distinctly challenged by Robert Boyle. The appearance in 1661 of his book, ', marks a turning-point in the history of chemistry."
"The "Chemico-physical Doubts and Paradoxes" raised by Boyle "touching the experiments whereby vulgar Spagyrists are wont to endeavour to evince their Salt, Sulphur, and Mercury to be the true Principles of Things," eventually sealed the fate of the doctrine of the tria prima, and of the tenets of the school of Paracelsus."
"He became a member of what was known as the , a small association of men interested in the new philosophy, who met at each other's houses in London, and occasionally at Gresham College, "to discourse and consider of philosophical inquiries and such as related thereunto." The meetings were subsequently held in , and Boyle took up his residence there in 1654. Here—in association with Wilkins; John Wallis and Seth Ward, the two Savilian Professors of Geometry and Astronomy; , the physician, then student of Christ Church; Christopher Wren, then Fellow of All Souls' College; Goddard, Warden of Merton; and , Fellow of Trinity, and afterwards its President—they sought to cultivate the new philosophy, "being satisfied that there was no certain way of arriving at any competent knowledge unless they made a variety of experiments upon natural bodies. In order to discover what phenomena they would produce, they pursued that method by themselves with great industry, and then communicated their discoveries to each other." The Invisible College eventually grew into the ..."
"Boyle was the first to formulate our present conception of an element in contradistinction to that of the Greeks and the schoolmen who influenced the theories of the iatro-chemists. In the sense understood by him, the Aristotelian elements were not true elements, nor were the salt, sulphur, and mercury of the school of Paracelsus."
"He was... the first to define the relation of an element to a compound, and to draw the distinction we still make between compounds and s."
"In this treatise Boyle sets out to prove that the number of the peripatetic elements or principles hitherto assumed by chemists is, to say the least, doubtful."
"Now a man need not be very conversant in the writings of Chymists to observe, in how Laxe, Indefinite, and almost Arbitrary Senses they employ the Terms of Salt, Sulphur and Mercury; of which I could never find that they were agreed upon any certain Definitions or setled Notions; not onely differing Authors, but not unfrequently one and the same, and perhaps in the same Book, employing them in very differing senses."
"Since a great part of those Learned Men, especially Physicians who have discerned the defects of the vulgar Philosophy, but are not yet come to understand and relish the Corpuscularian, have slid into the Doctrine of the Chymists; and since the Spagyrists are wont to pretend to make out all the Qualities of bodies from the Predominancy of some one of their three Hypostatical Principles, I suppose it may both keep my opinion from appearing too presumptuous, and (which is far more considerable) may make way for the fairer Reception of the Mechanical Hypothesis about Qualities, if I here intimate (though but briefly and in general) some of those defects, that I have observed in Chymists Explications of Qualities."
"And first the Doctrine that all their Theory is grounded on, seems to me Inevident and undemonstrated, not to say precarious."
"I am glad (sayes Eleutherius) to see the Vanity or Envy of the canting Chymists thus discover'd and chastis'd; and I could wish, that Learned Men would conspire together to make these deluding Writers sensible, that they must no longe[r] hope with Impunity to abuse the World. For whilst such Men are quietly permitted to publish Books with promising Titles, and therein to Assert what they please, and contradict others, and ev'n themselves as they please, with as little danger of being confuted as of being understood, they are encourag'd to get themselves a name, at the cost of the Readers, by finding that intelligent Men are wont for the reason newly mention'd, to let their Books and Them alone: And the ignorant and credulous (of which the number is still much greater then that of the other) are forward to admire most what they least understand."
"I consider, that as generally as Chymists are wont to appeal to Experience, and as confidently as they use to instance the several substances separated by the Fire from a Mixt Body, as a sufficient proof of their being its component Elements: Yet those differing Substances are many of them farr enough from Elementary simplicity, and may be yet look'd upon as mixt Bodies, most of them also retaining, somewhat... of the Nature of those Concretes whence they were forc'd."
"But if judicious men skilled in Chymical affairs shall once agree to write clearly and plainly of them, and thereby keep men from being stunn'd... or imposed upon by dark and empty Words; 'tis to be hop'd that these men finding that they can no longer write impertinently and absurdly, without being laugh'd at for doing so, will be reduc'd either to write nothing, or Books that may teach us something, and not rob men, as formerly, of invaluable Time; and so ceasing to trouble the world with Riddles or Impertinencies, we shall either by their Books receive an Advantage, or by their silence escape an Inconvenience."
"It is somewhat strange to me, that neither the Spagyrists themselves, nor yet their Adversaries, should have taken notice that Chymists have rather supposed than evinced, that the Analysis of bodies by fire, or even that at least some Analysis is the onely instrument of investigating what Ingredients mixt bodies are made up of, since in divers cases That may be discovered by Composition as well as by Resolution; as it may appear, that consists of metalline parts (whether Martial, or Venereal, or both) associated by Coagulation with ones, one may, I say, discover this as well by making true Vitriol with Spirit (improperly called Oil) of Sulphur, or that of Salt, as by distilling or Resolving Vitriol by the fire."
"And if the matter of the Philosophers Stone, and the manner of preparing it, be such Mysteries as they would have the World believe them, they may Write Intelligibly and Clearly of the Principles of mixt Bodies in General, without Discovering what they call the Great Work."
"But though much may be said to Excuse the Chymists when they write Darkly, and Ænigmatically, about the Preparation of their Elixir, and Some few other grand Arcana, the divulging of which they may upon Grounds Plausible enough esteem unfit; yet when they pretend to teach the General Principles of Natural Philosophers, this Equivocall Way of Writing is not to be endur'd. For in such Speculative Enquiries, where the naked Knowledge of the Truth is the thing Principally aim'd at, what does he teach me worth thanks that does not, if he can, make his Notion intelligible to me, but by Mystical Termes, and Ambiguous Phrases darkens what he should clear up; and makes me add the Trouble of guessing at the sence of what he Equivocally expresses, to that of examining the Truth of what he seems to deliver."
"But for my part (Continues Carneades) what my Indignation at this Un-philosophical way of teaching Principles has now extorted from me, is meant chiefly to excuse my self, if I shall hereafter oppose any Particular Opinion or assertion, that some Follower of Paracelsus or any Eminent Artist may pretend not to be his Masters. For, as I told you long since, I am not Oblig'd to examine private mens writings, (which were a Labour as endless as unprofitable) being only engag'd to examine those Opinions about the Tria Prima, which I find those Chymists I have met with to agree in most: And I Doubt not but my Arguments against their Doctrine will be in great part easily enough applicable ev'n to those private Opinions, which they do not so directly and expresly oppose."
"As for the Mystical Writers scrupling to Communicate their Knowledge, they might less to their own Disparagement, and to the trouble of their Readers, have conceal'd it by writing no Books, then by Writing bad ones. If Themistius were here, he would not stick to say that Chymists write thus darkly, not because they think their Notions too precious to be explain'd, but because they fear that if they were explain'd, men would discern, that they are farr from being precious."
"I must confess (sayes Eleutherius) I have, in the reading of Paracelsus and other Chymical Authors, been troubled to find, that such hard Words and Equivocal Expressions, as You justly complain of, do even when they treat of Principles, seem to be studiously affected by those Writers; whether to make themselves to be admir'd by their Readers, and their Art appear more Venerable and Mysterious, or, (as they would have us think) to conceal from them a Knowledge themselves judge inestimable."
"I fear that the chief Reason why Chymists have written so obscurely of their three Principles, may be, That not having Clear and Distinct Notions of them themselves, they cannot write otherwise then Confusedly of what they but Confusedly Apprehend. Not to say that divers of them, being Conscious to the Invalidity of their Doctrine, might well enough discerne that they could scarce keep themselves from being confuted, but by keeping themselves from being clearly understood."
"[T]hat which I am now entering upon being the Consideration of the things themselves whereinto Spagyrists resolve mixt Bodies by the Fire, If I can shew that these are not of an Elementary Nature, it will be no great matter what names these or those Chymists have been pleased to give them. And I question not that to a Wise man, and consequently to Eleutherius, it will be lesse considerable to know, what Men Have thought of Things, then what they Should have thought."
"But I will not... trouble you with what I have largely discoursed in the Sceptical Chymist, to call in question the grounds on which Chymists assert, that all mixt bodies are compounded of Salt, Sulphur, and Mercury. For it may suffice me now to tell you that, whatsoever they may be able to obtain from other bodies, it does not appear by Experience, which is the grand, if not the onely, Argument they rely on, that all mixt bodies that have Qualities consist of their tria prima, since they have not been able, that we know, truly, and without new Compositions, to resolve into those three, either Gold, or Silver, or Crystal, or Venetian Talck, or some other bodies, that I elsewhere name; & yet these bodies are endowed with divers Qualities, as the two former with Fusibleness and Malleability, and all of them with Weight and Fixity; so that in these and the like bodies, whence Chymisats have not made it yet appear, that their Salt, Sulphur and Mercury, can be truly and adequately separated, 'twill scarce be other than precarious to derive the malleableness, colour, and other Qualities of such bodies from those Principles."
"There are some mixt bodies, from which it has not been yet made appear, that any degree of fire can separate either salt, or sulphur, or mercury, much less all the three. The most obvious instance of this truth is gold, which is a body so fixed, and wherein the elementary ingredients (if it have any) are so firmly united to each other, that we find not in the operations, wherein gold is exposed to the fire, how violent soever, that it does discernably so much as lose of its fixedness or weight, so far is it from being dissipated into those principles, whereof one at least is acknowledged to be fugitive enough."
"Those distinct substances, which concretes generally either afford, or are made up of, may, without very much inconvenience, be called the elements or principles of them."
"I need not tell you, what complaints the more candid and judicious of the Chymists themselves are wont to make of those boasters, that confidently pretend, that they have extracted the salt or sulphur of quicksilver, when they have disguised it by additaments, wherewith it resembles the concretes, whose names are given it; whereas by a skilful and rigid examen, it may be easily enough stripped of its disguises, and made to appear again in the pristine form of running mercury. The pretended salts and sulphurs being so far from being elementary parts extracted out of the body of mercury, that they are rather... de-compound bodies, made up of the whole metal and the menstruum, or other additaments employed to disguise it."
"It seems not absurd to conceive, that at first production of mixt bodies, the universal matter, whereof they among other parts of the universe consisted, was actually divided, into little particles, of several sizes and shapes, variously moved."
"Being Gentlemen and very far from the litigious humour of loving to wrangle about words or terms or notions as empty; they had before his coming in, readily agreed promiscuously to use when they pleased Elements and Principles as terms equivalent: and to understand both by the one and the other, those primitive and simple bodies of which the mixt ones are said to be composed, and into which they are ultimately resolved."
"Epicurus... supposes not only all mixt bodies, but all others to be produced by the various and casual occursions of atoms, moving themselves to and fro by an internal principle in the immense or rather infinite vacuum."
"As for silver, I never could see any degree of fire make it part with any of its three principles. ...But admitting, that some parts of the silver were driven away by the violence of the fire, what proof is there, that it was either the salt, the sulphur, or the mercury of the metal, and not rather a part of it homogeneous to what remained? for besides that the silver, that was left, seemed not sensibly altered, which probably would have appeared, had so much of any one of its principles been separated from it."
"I observe, that of late Chymistry begins, as indeed it deserves, to be cultivated by Learned Men who before despis’d it; and to be pretended to by many who never cultivated it, that they may be thought not to ignore it: Whence it is come to passe, that divers Chymical Notions about Matters Philosophical are taken for granted and employ’d, and so adopted by very eminent Writers both Naturalists and Physitians. Now this I fear may prove somewhat prejudicial to the Advancement of solid Philosophy: For though I am a great Lover of Chymical Experiments, and though I have no mean esteem of divers Chymical Remedies, yet I distinguish these from their Notions about the causes of things, and their manner of Generation."
"For it has been truly observed by a great philosopher, that truth does more easily emerge out of error than confusion."
"That then, that I wish for, as to systems, is this, that men, in the first place, would forbear to establish any theory, till they have consulted with (though not a fully competent number of experiments, such as may afford them all the phænomena to be explicated by that theory, yet) a considerable number of experiments, in proportion to the comprehensiveness of the theory to be erected on them. And, in the next place, I would have such kind of supestructures looked upon only as temporary ones; which though they may be preferred before any others, as being the least imperfect, or, if you please, the best in their kind that we yet have, yet are they not entirely to be acquiesced in, as absolutely perfect, or uncapable of improving alterations."
"A Person any Thing vers’d in the Writings of Chymists cannot but Discern by their obscure, Ambiguous, and almost Ænigmatical Way of expressing what they pretend to Teach, that they have no Mind, to be understood at all, but by the Sons of Art (as they call them) nor to be Understood even by these without Difficulty And Hazardous Tryalls."
"I remember, that being once at Leyden, I was brought to the top of a tower, where, in a darkened room (such as is now used in many places to bring in the species of external object) a convex glass, applied to the only hole, by which light was permitted to enter, did project upon a large white sheet of paper, held at a just distance from it, a lively representation of divers of the chief buildings in the town; all which, upon the admission of more light into the room, by opening the window, did immediately disappear, And methinks... that in divers of the philosophical theories, that have been formerly applauded, something not unlike this may be easily observed. for though, whilst they are looked on with such a weak and determinate degree of light, they may appear very artificial and well-proportioned fabrics, yet they appear so but in that twilight, as it were, which is requisite to their conspicuousness. For if but a full light of new experiments and observations be freely let in upon them, the beauty of those (delightful, but fantastical) structures does immediately vanish."