IN the Tract of Heat and Cold , p. 28. at the end of the page dele Finis ▪ and go ▪ on to Exp. IX . p. 40. l. 21. r. degree of rapidness . p. 102. l. 15. put a comma after the word before .

In the Tract of Corrosiveness and Corrosibility read in the current Title on the top of p. 2. and 3. & seqq . Corrosiveness and Corrosibility , nor or .

TO keep the Reader from being at all surpriz'd at the Date of the Title-Page , I must inform him , that a good part of the ensuing Tracts were Printed off , and in my custody , the last year ; and the rest had come out with them divers moneths ago , if the Noble Author had not been hinder'd from committing them to the Press by the desire and hope of being able in a short time to send them abroad more numerous , and by his being hinder'd to do so partly by Remove , partly by the want of some Papers that were odly lost or spoil'd , and partly by the sickness of himself , and divers of his near Relations . And some of these Impediments do yet suppress what the Author intended should have made a part of the Book , which now he suffers to be publish'd without them , though divers of his Papers about some other particular Qualities have been written so long ago , as to have lain for many years neglected among other of his old Writings : Which that he may have both leasure and health to review , and fit for publication , is the ardent wish of the sincere Lovers of Real Knowledge , who have reason to look on it as no mean proof of his constant kindness to Experimental Philosophy , that in these Tracts he perseveres in his course of freely and candidly communicating his Experiments and Observations to the publick , notwithstanding the liberty that hath been too boldly taken to mention them as their own by some later Writers ; as particularly by the Compiler of the Treatise , entitul'd Polygraphice , who in two Chapters hath allow'd himself to present his Reader with above Fifty Experiments , taken out of our Authors Book of Colours , without owning any one of them to Him , or so much as naming him or his Book in either of those Chapters ▪ nor , that I remember , in any of the others . Nor did I think this practice justified by the confession made in the Preface , importing , that the Compiler had taken the particulars he deliver'd from the Writings of others . For , this general and perfunctory acknowledgment neither doth right to particular Authors , nor , by naming them , enables the Reader to know , whether the things deliver'd come from persons fit to be credited or not : And therefore , since 't is but too likely , that such Concealment of the Names , if not Vsurpation of the Labours of the Benefactors to Philosophy , will prove much more forbidding to many others to impart their Experiments , than as yet they have to our generous Author ; it seems to be the Interest of the Commonwealth of Learning openly to discountenance so discouraging a practice , and to shew , that they do not think it fit that Possessors of useful pieces of knowledge should be strongly tempted to envy them to the Publick , to the end onely that a few Compilers should not be put upon so reasonable and easie a work , as by a few words or names to shew themselves just , if not grateful .

But not to keep the Reader any longer from the perusal of these Tracts themselves , I shall conclude with intimating onely , that what our Author saith in one of them concerning the Insufficiency of the Chymical Hypothesis for explaining the Effects of Nature , is not at all intended by him to derogate from the sober Professors of Chymistry , or to discourage them from useful Chymical Operations ; forasmuch as I had the satisfaction , some years since , to see in the Authors hands a Discourse of his about the Usefulness of Chymistry for the Advancement of Natural Philosophy ; with which also 't is hoped he will e're long gratifie the Publick .

TO obviate some misapprehensions that may arise concerning the ensuing Notes about Particular Qualities , it may not be improper to adde something in this place to what has been said in another Paper in reference to those Notes , and consequently to premise to the particular Experiments some few general Advertisements about them .

And I. we may consider , that there may be three differing ways of treating Historically of Particular Qualities . For either one may in a full and methodical History prosecute the Phaenomena ; or one may make a Collection of various Experiments and Observations whence may be gathered divers Phaenomena to illustrate several , but not all of the Heads or Parts of such an ample or methodical History ; or ( in the third place ) one may in a more confin'd way content ones self to deliver such Experiments and Observations of the Production , or the Destruction or Change of this or that Quality , as , being duly reason'd on , may suffice to shew wherein the nature of that Quality doth consist , especially in opposition to those erroneous conceits that have been entertained about it . Of the First of these three ways of treating of a Quality I pretend not to have given any compleat example ; but you will find , that I have begun such Histories in my Specimens about Fluidity and Firmness , and in the Experiments , Observations , &c. that I have put together about Cold. The Second sort of Historical Writings I have given an Instance of in my Experiments about Colours ; but in these ensuing Notes , the occasion I had to make them having obliged me chiefly to have an eye to the disproval of the errours of the Peripateticks and the Chymists about them , I hope I shall not be thought to have fallen very short in my Attempt , if I have ( here and there ) perform'd what may be required in the Third way of writing Historically of a Quality ; my present Design being chiefly to give an Intelligent and Historical Account of the Possible Mechanical Origination , not of the various Phaenomena of the particular Qualities succinctly mentioned in these Notes ; though , my secondary end being to become a Benefactor to the History of Qualities by providing Materials for my self or better Architects , I have not scrupled to adde to those , that tend more directly to discover the Nature or Essence of the Quality treated of , and to derive it from Mechanical Principles , some others ( which happen'd to come in my way ) that acquaint us but with some of the less luciferous Phaenomena .

II. That you may not mistake what is driven at in many of the Experiments and Reasonings deliver'd or propos'd in the ensuing Notes about Particular Qualities , I must desire you to take notice with me , what it is that I pretend to offer you some proofs of . For , if I took upon me to demonstrate , that the Qualities of bodies cannot proceed from ( what the Schools call ) Substantial Forms , or from any other Causes but Mechanical , it might be reasonably enough expected , that my Argument should directly exclude them all . But since , in my Explications of Qualities , I pretend only , that they may be explicated by Mechanical Principles , without enquiring , whether they are explicable by any other ; that which I need to prove , is , not that Mechanical Principles are the necessary and onely things whereby Qualities may be explain'd , but that probably they will be found sufficient for their explication . And since these are confessedly more manifest and more intelligible than substantial Forms and other Scholastic Entities ( if I may so call them ) 't is obvious , what the consequence will be of our not being oblig'd to have recourse to things , whose existence is very disputable , and their nature very obscure .

There are several ways that may be employed , some on one occasion , and some on another , either more directly to reduce Qualities ( as well as divers other things in nature ) to Mechanical Principles ; or , by shewing the insufficiency of the Peripatetic and Chymical Theories of Qualities , to recommend the Corpuscularian Doctrine of them .

For further Illustration of this Point , I shall adde on this occasion , that there are three distinct sorts of Experiments ( besides other proofs ) that may be reasonably employ'd , ( though they be not equally efficacious ) when we treat of the Origine of Qualities . For some Instances may be brought to shew , that the propos'd Quality may be Mechanically introduc'd into a portion of matter , where it was not before . Other Instances there may be to shew , that by the same means the Quality may be notably varied as to degrees , or other not essential Attributes . And by some Instances also it may appear , that the Quality is Mechanically expell'd from , or abolish'd in , a portion of matter that was endow'd with it before . Sometimes also by the same Operation the former quality is destroyed , and a new one is produc'd . And each of these kinds of Instances may be usefully employ'd in our Notes about Particular Qualities . For , as to the first of them , there will be scarce any difficulty . And as to the second , since the permanent Degrees as well as other Attributes of Qualities are said to flow from ( and do indeed depend upon ) the same Principles that the Quality it self does ; if , especially in bodies inanimate , a change barely Mechanical does notably and permanently alter the degree or other considerable attribute ; it will afford , though not a clear proof , yet a probable presumption , that the Principles whereon the Quality it self depends are Mechanical . And lastly , if , by a bare Mechanical change of the internal Disposition and structure of a body , a permanent Quality , confess'd to flow from its substantial Form or inward Principle , be abolish'd , and perhaps also immediately succeeded by a new Quality Mechanically producible ; if , I say , this come to pass in a body Inanimate , especially if it be also , as to sense similar , such a Phaenomenon will not a little favour that Hypothesis which teaches , that these Qualities depend upon certain contextures and other Mechanical Affections of the small parts of the bodies , that are indowed with them , and consequently may be abolish'd when that necessary Modification is destroyed . This is thus briefly premis'd to shew the pertinency of alledging differing kinds of Experiments and Phaenomena in favour of the Corpuscular Hypothesis about Qualities .

What has been thus laid down , may , I hope , facilitate and shorten most of the remaining work of this Preamble , which is to shew , though but very briefly , that there may be several ways , not impertinently employable to recommend the Corpuscularian Doctrine of Qualities .

For first , it may sometimes be shewn , that a Substantial Form cannot be pretended to be the necessary Principle of this or that Quality ; as will ( for instance ) hereafter be made manifest in the Asperity and Smoothness of bodies , and in the Magnetical Vertue residing in a piece of Iron that has been impregnated by a Loadstone . 'T is true , that the force of such Instances is indirect , and that they do not expresly prove the Hypothesis in whose favour they are alledged ; but yet they may do it good service by disproving the Grounds and Conclusions of the Adversaries , and so ( by removing Prejudices , ) making way for the better entertainment of the truth .

Secondly , we may sometimes obtain the same or the like Quality by Artificial and sometimes even temporary Compositions , which , being but factitious bodies , are by Learned Adversaries confess'd not to have Substantial Forms , and can indeed reasonably be presum'd to have but resulting Temperaments : As will be hereafter exemplifi'd in the production of Green by compounding Blew and Yellow , and in the Electrical Faculty of Glass ; and in the temporary whiteness produc'd by beating clear Oyl and fair Water into an Ointment , and by beating water into a froth , and , more permanently , in making Coral white by flawing it with heat ; and in divers other Particulars , that will more properly be elsewhere mention'd .

Thirdly then , in some cases the Quality propos'd may be either introduced ; or vary'd , or distroy'd in an inanimate body , when no change appears to be made in the body , except what is Mechanical , and what might be produc'd in it , supposing such a parcel of matter were artificially fram'd and constituted as the body is , though without any Substantial Form , or other such like internal Principle . So when a piece of Glass , or of clarify'd Rosin , is , by being beaten to powder , deprived of its Transparency , and made white , there appears no change to be made in the pulveriz'd body , but a comminution of it into a multitude of Corpuscles , that by their number and the various scituations of their surfaces are fitted copiously to reflect the sincere Light several ways , or give some peculiar Modification to its Rayes ; and hinder that free passage of the beams of Light , that is requisite to Transparency .

Fourthly , as in the cases belonging to the foregoing number there appears not to intervene in the Patient or Subject of the change , any thing but a Mechanical alteration of the Mechanical Structure or Constitution ; so in some other cases it appears not , that the Agent , whether natural or factitious , operates on the Patient otherwise than Mechanically , employing onely such a way of acting as may proceed from the Mechanisme of the matter , which it self consists of , and that of the body it acts upon . As when Goldsmiths burnish a Plate or Vessel of Silver , that having been lately boil'd lookt white before , though they deprive it of the greatest part of its colour , and give it a new power of reflecting the beams of Light and visible Objects , in the manner proper to specular bodies ; yet all this is done by the intervention of a burnishing Tool , which often is but a piece of Steel or Iron conveniently shap'd ; and all that this Burnisher does , is but to depress the little prominencies of the Silver , and reduce them , and the little cavites of it , to one physically level or plain Superficies . And so when a Hammer striking often on a Nail , makes the head of it grow hot , the Hammer is but a purely Mechanical Agent , and works by local motion . And when by striking a lump of Glass , it breaks it into a multitude of small parts that compose a white powder , it acts as Mechanically in the production of that Whiteness as it does in driving in a Nail to the head . And so likewise , when the powder'd Glass or Colophony lately mention'd is , by the fire , from a white and opacous body , reduc'd into a colourless ( or a reddish ) and transparent one , it appears not , that the fire , though a natural Agent , need work otherwise than Mechanically , by colliquating the incoherent grains of powder into one mass ; wherein , the ranks of pores not being broken and interrupted as before , the incident beams of Light are allow'd every way a free passage through them .

Fifthly , the like Phaenomena to those of a Quality to be explicated , or at least as difficult in the same kind , may be produc'd in bodies and cases , wherein 't is plain we need not recurre to Substantial Forms . Thus a varying Colour , like that which is admired in a Pigeons Neck , may be produc'd in changeable Taffety , by a particular way of ranging and connecting Silk of several Colours into one piece of Stuff . Thus we have known Opals casually imitated and almost excell'd by Glass , which luckily degenerated in the Furnace . And somewhat the like changeable and very delightful Colour I remember to have introduced into common Glass with Silver or with Gold and Mercury . So likewise meerly by blowing fine Crystal-Glass at the flame of a Lamp to a very extraordinary thinness , we have made it to exhibit , and that vividly , all the Colours ( as they speak ) of the Rainbow ; and this power of pleasing by diversifying the Light , the Glass , if well preserved , may keep for a long time . Thus also by barely beating Gold into such thin leaves as Artificers and Apothecaries are wont to employ , it will be brought to exhibite a green Colour , when you hold it against the Light , whether of the day , or of a good Candle ; and this kind of Greenness as 't is permanent in the foliated Gold , so I have found by trial , that if the Sun-beams , somewhat united by a Burning-glass , be trajected through the expanded Leaf , and cast upon a piece of white paper , they will appear there as if they had been tinged in their passage . Nay , and sometimes a flight and almost momentany Mechanical change will seem to over-rule Nature , and introduce into a body the quite opposite Quality to that she had given it : As when a piece of black Horn is , onely by being thinly scraped with the edge of a knife or a piece of glass , reduced to permanently white Shavings . And to these Instances o● Colours , some Emphatical and some Permanent , might be added divers belonging to other Qualities , but that I ought not to anticipate what you will elsewhere meet with .

There is yet another way of arguing in favour of the Corpuscularian Doctrine of Qualities , which , though it do not afford direct proofs of its being the best Hypothesis , yet it may much strengthen the Arguments drawn from other Topicks , and thereby serve to recommend the Doctrine it self . For , the use of an Hypothesis being to render an intelligible account of the Causes of the Effects or Phaenomena propos'd , without crossing the Laws of Nature or other Phaenomena , the more numerous and the more various the Particulars are , whereof some are explicable by the assign'd Hypothesis , and some are agreeable to it , or at least are not dissonant from it , the more valuable is the Hypothesis , and the more likely to be true . For 't is much more difficult , to finde an Hypothesis that is not true which will suit with many Phaenomena , especially if they be of various kinds , than but with few . And for this Reason I have set down among the Instances belonging to particular Qualities some such Experiments and Observations , as we are now speaking of , since , although they be not direct proofs of the preferrableness of our Doctrine , yet they may serve for Confirmation of it ; though this be not the only or perhaps the chief Reason of their being mention'd . For whatever they may be as Arguments , since they are matters of fact , I thought it not amiss to take this occasion of preserving them from being lost ; since , whether or no they contribute much to the establishment of the Mechanical Doctrine about Qualities , they will at least contribute to the Natural History of them .

III. I shall not trouble the Reader with a Recital of those unlucky Accidents , that have hinder'd the Subjects of the following Book from being more numerous , and I hope he will the more easily excuse their paucity , if he be advertised , that although the particular Qualities , about which some Experiments and Notes , by way of Specimens , are here presented , be not near half so many as were intended to be treated of ; yet I was careful to chuse them such as might comprehend in a small number a great variety ; there being scarce one sort of Qualities , of which there is not an Instance given in this small Book , since therein Experiments and thoughts are deliver'd about Heat and Cold , which are the chief of the four FIRST QVALITIES ; about Tasts and Odours , which are of those , that , being the immediate objects of Sense , are wont to be call'd SENSIBLE QVALITIES ; about Volatility and Fixity , Corrosiveness and Corrosibility , which , as they are found in bodies purely natural , are referrable to those Qualities , that many Physical Writers call SECOND QVALITIES , and which yet , as they may be produced and destroyed by the Chymists Art , may be stiled Chymical Qualities , and the Spagyrical ways of introducing or expelling them may be referr'd to Chymical Operations , of which there is given a more ample Specimen in the Mechanical account of Chymical Precipitations . And lastly , some Notes are added about Magnetism and Electricity , which are known to belong to the Tribe of Occult Qualities .

IV. If a want of apt Coherence and exact Method be discover'd in the following Essays , 't is hop'd , that defect will be easily excus'd by those that remember and consider , that these Papers were originally little better than a kind of Repsody of Experiments , Thoughts , and Observations , occasionally thrown together by way of Annotations upon some Passages of a Discourse ▪ ( about the differing Parts and Red integration of Nitre ) wherein some things were pointed at relating to the particular Qualities that are here more largely treated of . And though the Particulars that concern some of these Qualities , were afterwards ( to supply the place of those borrow'd by other Papers whilst these lay by me ) increas'd in number ; yet it was not to be expected , that their Accession should as well correct the Form as augment the Matter of our Annotations . And as for the two Tracts , that are inserted among these Essays about Qualities ; I mean the Discourse of the Imperfection of the Chymical Doctrine of them , and the Reflections on the Hypothesis of Acidum and Alcali , the occasion of their being made parts of this Book is so far express'd in the Tracts themselves , that I need not here trouble the Reader with a particular Account of it .

V. I do not undertake , that all the following Accounts of Particular Qualities would prove to be the very true ones , nor every Explication the best that can be devis'd . For besides that the difficulty of the Subject , and Incompleatness of the History we yet have of Qualities , may well deterre a man , less diffident of his own abilities than I justly am , from assuming so much to himself , it is not absolutely necessary to my present Design . For , Mechanical Explications of natural Phaenomena do give so much more satisfaction to ingenious minds , than those that must employ Substantial Forms , Sympathy , Antipathy , &c. that the more judicious of the vulgar Philosophers themselves prefer them before all others , when they can be had ; ( as is elsewhere shewn at large , ) but then they look upon them either as confined to Mechanical Engines , or at least but as reaching to very few of Nature's Phaenomena , and , for that reason , unfit to be received as Physical Principles . To remove therefore this grand Prejudice and Objection , which seems to be the chief thing that has kept off Rational Inquirers from closing with the Mechanical Philosophy , it may be very conducive , if not sufficient , to propose such Mechanical accounts of Particular Qualities themselves , as are intelligible and possible , and are agreeable to the Phaenomena whereto they are applied . And to this it is no more necessary that the account propos'd should be the truest and best that can possibly be given , than it is to the proving that a Clock is not acted by a vital Principle , ( as those Chineses thought , who took the first , that was brought them out of Europe , for an Animal , ) but acts as an Engine , to do more than assign a Mechanical Structure made up of Wheels , a Spring , a Hammer , and other Mechanical pieces , that will regularly shew and strike the hour , whether this Contrivance be or be not the very same with that of the Particular Clock propos'd ; which may indeed be made to move either with Springs or Weights , and may consist of a greater or lesser number of Wheels , and those differingly scituated and connected ; but for all this variety 't will still be but an Engine . I intend not therefore by proposing the Theories and Conjectures ventur'd at in the following Papers , to debar my self of the Liberty either of altering them , or of substituting others in their places , in case a further progress in the History of Qualities shall suggest better Hypotheses or Explications . And 't was but agreeable to this Intention of mine , that I should , as I have done , on divers occasions in the following Notes , imploy the word Or , and express my self somewhat doubtingly , mentioning more than one Cause of a Phaenomenon , or Reason of an opinion , without dogmatically declaring for either ; since my purpose in these Notes was rather to shew , it was not necessary to betake our selves to the Scholastick or Chymical Doctrine about Qualities , than to act the Umpire between the differing Hypotheses of the Corpuscularians ; and , provided I kept my self within the bounds of Mechanical Philosophy , my design allowed me a great latitude in making explications of the Phaenomena , I had occasion to take notice of .