upon a power that certain bodies have to cause Precipitation and some upon such a Disposition to be struck down by others as may if men please be called Precipitability And so these differing Affections may with at least tolerable Congruity be referred to those that we have elsewhere stiled Chymical Qualities But though I hope I may in these few Lines have said enough concerning the name given to these Attributes yet perhaps it will be found in time that the things themselves may deserve a larger Discourse than my little leasure would allow them For that is not a causeless Intimation of the Importance of the subject wherewith I conclude the following Tract since besides that many more Instances might have been particularly referred to the Heads treated of in the Insuing Essay there are improper kinds of Precipitation besides those mentioned in the former part of the Discourse to which one may not incongruously refer divers of the Phaenomena of Nature as well in the greater as in the lesser world whereof either no Causes at all or but improper ones are wont to be given And besides the simple Spirits and Salts usually employed by Chymists there are many compounded and decompounded bodies not only factitious but natural and some such as one would scarce suspect that may in congruous subjects produce such Precipitations as I speak of And the Phaenomena and Consequents of such operations may in divers cases prove conducive both to the Discovery of Physical Causes and the Production of useful effects though the particularizing of such Phaenomena do rather belong to a History of Precipitations than to such a Discourse as that which follows wherein I proposed not so much to deliver the latent Mysteries as to investigate the Mechanical Causes of Precipitation OF THE MECHANICAL CAUSES OF CHYMICAL PRECIPITATION CHAP. I. BY Precipitation is here meant such an agitation or motion of a heterogeneous liquor as in no long time makes the parts of it subside and that usually in the form of a powder or other consistent body As on many occasions Chymists call the substance that is made to fall to the bottom of the liquor the Precipitate so for brevity sake we shall call the body that is put into the liquor to procure that subsiding the Precipitant as also that which is to be struck down the Precipitable substance or matter and the liquor wherein it swims before the separation the Menstruum or Solvent When a hasty fall of a heterogeneous body is procured by a Precipitant the Operation is called Precipitation in the proper or strict sense But when the separation is made without any such addition or the substance separated from the fluid part of the liquor instead of subsiding emerges then the word is used in a more comprehensive but less proper acceptation As for the Causes of Precipitation the very name it self in its Chymical sense having been scarce heard of in the Peripatetic Schools it is not to be expected that they should have given an account of the Reasons of the thing And 't is like that those few Aristotelians that have by their converse with the laboratories or writings of Chymists taken notice of this Operation would according to their custom on such occasions have recourse for the explication of it to some secret sympathy or antipathy between the bodies whose action and reaction intervenes in this Operation But if this be the way proposed of accounting for it I shall quickly have occasion to say somewhat to it in considering the ways proposed by the Chymists who were wont to refer Precipitation either as is most usual to a sympathy betwixt the Precipitating body and the Menstruum which makes the Solvent run to the embraces of the Precipitant and so let fall the particles of the body sustained before or with others to a great antipathy or contrariety between the acid salt of the Menstruum and the fixed salt of the Oil or solution of calcined Tartar which is the most general and usual Precipitant they imploy But I see not how either of these causes will either reach to all the Phaenomena that have been exhibited or give a true account even of some of those to which it seems applicable For first in Precipitations wherein what they call a sympathy between the liquors is supposed to produce the effect this admired sympathy does not in my apprehension evince such a mysterious occult Quality as is presumed but rather consists in a greater congruity as to bigness shape motion and pores of the minute parts between the Menstruum and the Precipitant than between the same Solvent and the body it kept before dissolved And though this sympathy rightly explained may be allowed to have an interest in some such Precipitations as let fall the dissolved body in its pristine nature and form and only reduced into minute powder yet I find not that in the generality of Precipitations this Doctrine will hold For in some that we have made of Gold and Silver in proper Menstruums after the subsiding matter had been well washed and dried several Precipitates of Gold made some with oil of Tartar which abounds with a fixed salt and is the usual Precipitant and some with an Urinous Spirit which works by Vertue of a salt highly fugitive or Volatile I found the powder to exceed the weight of the Gold and Silver I had put to dissolve and the Eye it self sufficiently discovers such Precipitates not to be meer metalline powders but Compositions whose consisting not as hath been by some body suspected of the combined Salts alone but of the metalline parts also may be strongly concluded not only from the ponderousness of divers of them in reference to their bulk but also manifestly from the reduction of true malleable metals from several of them CHAP. II. THE other Chymical way of explicating Precipitations may in a right sence be made use of by a Naturalist on some particular occasions But I think it much too narrow and defective as 't is in a general way proposed to be fit to be acquiesced in For first 't is plain that 't is not only Salt of Tartar and other fixed Alcalies that precipitate most bodies that are dissolved in acid Menstruums as in making of Aurum fulminans oil of Tartar precipitates the Gold out of Aqua Regis But acid liquors themselves do on many occasions no less powerfully precipitate metals and other bodies out of one another Thus spirit of Salt as I have often tried precipitates Silver out of Aqua fortis The corrosive Spirit of Nitre copiously precipitates that white powder whereof they make Bezoardicum Minerale Spirit or oil of Sulphur made by a glass-bell precipitates Corals Pearls c. dissolved in Spirit of Vinegar as is known to many Chymists who now use this Oleum Sulphuris per Campanam to make the Magistery of Pearls c. for which vulgar Chymists imploy Oleum Tartari per deliquium I have sometimes made a Menstruum wherein
nature of the things and Helmont's Writings have been lately alledg'd against their Hypothesis I consider how slight accounts they are wont to give us even of the familiar Phaenomena of Corrosive Liquors For if for example you ask a vulgar Chymist why Aqua fortis dissolves Silver and Copper 't is great odds but he will tell you 't is because of the abundance of fretting Salt that is in it and has a cognation with the Salts of the Metal And if you ask him why Spirit of Salt dissolves Copper he will tell you 't is for the same reason and yet if you put Spirit of Salt though very strong to Aqua fortis this Liquor will not dissolve Silver because upon the mixture the Liquors acquire a new Gonstitution as to the Saline Particles by vertue of which the mixture will dissolve instead of Silver Gold Whence we may argue against the Chymists that the Inability of this compounded Liquor to work on Silver does not proceed from its being weaken'd by the Spirit of Salt as well because according to them Gold is far the more compact metal of the two and requires a more potent Menstruum to work upon it as because this same compounded Liquor will readily dissolve Copper And to the same purpose with this Experiment I should alledge divers others if I thought this the fittest place wherein I could propose them SECT II. About the Mechanicall Origine of CORROSIBILITY COrrosibility being the quality that answers Corrosiveness he that has taken notice of the Advertisement I formerly gave about my use of the Term Corrosiveness in these Notes may easily judge in what sense I employ the name of the other Quality which whether you will stile it Opposite or Conjugate for want of a better word I call Corrosibility This Corrosibility of Bodies is as well as their Corrosiveness a Relative thing as we see that Gold for instance will not be dissolved by Aqua fortis but will by Aqua Regis whereas Silver is not soluble by the latter of these Menstruums but is by the former And this relative Affection on whose account a Body comes to be corrodible by a Menstruum seems to consist chiefly in three things which all of them depend upon Mechanical Principles Of these Qualifications the first is that the Body to be corroded be furnish'd with Pores of such a bigness and figure that the Corpuscles of the Solvent may enter them and yet not be much agitated in them without giving brisk knocks or shakes to the solid parts that make up the walls if I may so call them of the Pores And 't is for want of this condition that Glass is penetrated in a multitude of places but not dissipated or dissolv'd by the incident beams of Light which permeate its Pores without any considerable resistance and though the Pores and Commissures of a Body were less minute and capable of letting in some grosser Corpuscles yet if these were for want of solidity or rigidness too flexible or were of a figure incongruous to that of the Pores they should enter the Dissolution would not insue as it happens when pure Spirit of Wine is in the cold put upon Salt of Tartar or when Aqua fortis is put upon powder of Sulphur The second Qualification of a Corrodible Body is that its consistent Corpuscles be of such a Bulk and Solidity as does not render them uncapable of being disjoyn'd by the action of the insinuating corpuscles of the Menstruum Agreeable to this and the former Observation is the practice of Chymists who oftentimes when they would have a Body to be wrought on by a Menstruum otherwise too weak for it in its crude estate dispose it to receive the action of the Menstruum by previously opening it as they speak that is by enlarging the Pores making a comminution of the Corpuscles or weakening their Cohesion And we see that divers Bodies are brought by fit preparations to be resoluble in Liquors that would not work on them before Thus as was lately noted Lime-stone by Calcination becomes in part dissoluble in water and some Metalline Calces will be so wrought on by Solvents as they would not be by the same Agents if the preparation of the Metalline or other Body had not given them a new Disposition Thus though crude Tartar especially in lumps is very slowly and difficultly dissoluble in cold water yet when 't is burnt it may be presently dissolved in that Liquor and thus though the Filings and the Calx of Silver will not be at all dissolv'd by common water or Spirit of Wine yet if by the interposition of the Saline Particles of Aqua Fortis the Lunar Corpuscles be so disjoyn'd and suffer such a comminution as they do in Crystals of Lune the Metal thus prepared and brought with its Saline Additament into a new Texture will easily enough dissolve not onely in water but as I have tried in well rectified Spirit of Wine And the like Solubility I have found in the Crystals of Lead made with Spirit of Verdigrease or good distill'd Vinegar and in those of Copper made with Aqua Fortis The last Disposition to Corrosibility consists in such a cohesion of the parts whereof a Body is made up as is not too strict to be superable by the action of the Menstruum This Condition though of kin to the former is yet somewhat differing from it since a body may consist of parts either bulky or solid which yet may touch one another in such small portions of their Surfaces as to be much more easily dissociable than the minute or less solid parts of another Body whose contact is more full and close and so their Cohesion more strict By what has been said it may seem probable that as I formerly intimated the Corrosibility of Bodies is but a Mechanical Relation resulting from the Mechanical Affectious and Contexture of its parts as they intercept Pores of such sizes and figures as make them congruous to those of the Corpuscles of the Menstruum that are to pierce between them and disjoyn them That the Quality that disposes the body it affects to be dissolv'd by Corrosive and other Menstruums does as hath been declared in many cases depend upon the Mechanical Texture and Affections of the body in reference to the Menstruum that is to work upon it may be made very probable by what we are in due place to deliver concerning the Pores of Bodies and Figures of Corpuscles But yet in compliance with the design of these Notes and agreeably to my custom on other Subjects I shall subjoyn a few Experiments on this occasion also EXPER. I. IF we put highly rectified Spirit of Wine upon crude Sulphur or even Flowers of Sulphur the Liquor will lie quietly thereon especially in the cold for many hours and days without making any visible Solution of it and if such exactly dephlegmed Spirit were put on very dry Salt of Tartar the Salt would lie in an
of the motion of the Flame upwards may render it very difficult for the Electrical Emanations to divert the Flame from its Course 10. We have found by Experiment That a vigorous and well excited piece of Amber will draw not onely the powder of Amber but less minute fragments of it And as in many cases one contrary directs to another so this Trial suggested a further which in case of good success would probably argue that in Electrical Attraction not onely Effluvia are emitted by the Electrical body but these Effluvia fasten upon the body to be drawn and that in such a way that the intervening viscous strings which may be supposed to be made up of those cohering Effluvia are when their agitation ceases contracted or made to shrink inwards towards both ends almost as a highly stretch'd Lute-string does when 't is permitted to retreat into shorter Dimensions But the Conjecture it self was much more easie to be made than the Experiment requisite to examine it For we found it no easie matter to suspend an Electric great and vigorous enough in such a manner that it might whilst suspended be excited and be so nicely poised that so faint a force as that wherewith it attracts light bodies should be able to procure a Lccal Motion to the whole Body it self But after some fruitless attempts with other Electricks I had recourse to the very vigorous piece of polish'd Amber formerly mention'd and when we had with the help of a little Wax suspended it by a silken thread we chafed very well one of the blunt edges of it upon a kind of large Pin-cushion cover'd with a course and black woollen stuff and then brought the Electric as soon as we could to settle notwithstanding its hanging freely at the bottom of the string This course of rubbing on the edge of the Amber we pitch'd upon for more than one reason for if we had chafed the flat side the Amber could not have approached the body it had been rub'd on without making a change of place in the whole Electric and which is worse without making it move contrary to the nature of heavy bodies somewhat upwards whereas the Amber having by reason of its suspension its parts counterpoised by one another to make the excited edge approach to another body that edge needed not at all ascend but onely be moved horizontally to which way of moving the gravity of the Electric which the string kept from moving downwards could be but little or no hinderance And agreeably to this we found that if as soon as the suspended and well rubb'd Electric was brought to settle freely we applied to the chafed edge but without touching it the lately mention'd Cushion which by reason of its rough Superficies and porosity was fit for the Electrical Effluvia to fasten upon the edge would manifestly be drawn aside by the Cushion steadily held and if this were slowly removed would follow it a good way and when this body no longer detain'd it would return to the posture wherein it had settled before And this power of approaching the Cushion by vertue of the operation of its own steams was so durable in our vigorous piece of Amber that by once chafing it I was able to make it follow the Cushion no less than ten or eleven times Whether from such Experiments one may argue that 't is but as 't were by accident that Amber attracts another body and not this the Amber and whether these ought to make us question if Electricks may with so much propriety as has been hitherto generally supposed be said to Attract are doubts that my Design does not here oblige me to examine Some other Phaenomena might be added of the same Tendency with those already mention'd as the advantage that Electrical Bodies usually get by having well polish'd or at least smooth Surfaces but the Title of this Paper promising some Experiments about the Production of Electricity I must not omit to recite how I have been sometimes able to produce or destroy this Quality in certain bodies by means of alterations that appear'd not to be other than Mechanical EXPER. I. ANd first having with a very mild heat slowly evaporated about a fourth part of good Turpentine I found that the remaining body would not when cold continue a Liquor but harden'd into a transparent Gum almost like Amber which as I look'd for proved Electrical EXPER. II. SEcondly by mixing two such liquid Bodies as Petroleum and strong Spirit of Nitre in a certain proportion and then distilling them till there remained a dry mass I obtain'd a brittle substance as black as Jet and whose Superficies where it was contiguous to the Retort was glossie like that Mineral when polished and as I expected I found it also to resemble Jet in being endowed with an Electrical Faculty EXPER. III. THirdly Having burnt Antimony to ashes and of those ashes without any addition made a transparent Glass I found that when rubb'd as Electrical Bodies ought to be to excite them it answer'd my expectation by manifesting a not inconsiderable Electricity And this is the worthier of notice because that as a Vitrum Antimonii that is said to be purer than ordinary may be made of the Regulus of the same Mineral in whose preparation you know a great part of the Antimonial Sulphur is separated and left among the Scoriae so Glass of Antimony made without additament may easily as experience has inform'd us be in part reduc'd to a Regulus a Body not reckon'd amongst Electrical ones And that you may not think that 't is onely some peculiar and fixt part of the Antimony that is capable of Vitrification let me assure you that even with the other part that is wont to flye away namely the Flowers an Antimonial Glass may without an addition of other Ingredients be made EXPER. IV. FOurthly The mention of a Vitrified Body brings into my mind that I more than once made some Glass of Lead per se which I found no very easie work that also was not wholly destitute of an Electrical Vertue though it had but a very languid one And it is not here to be overlook'd that this Glass might easily be brought to afford again malleable Lead which was never reckon'd that I know of among Electrical Bodies EXPER. V. FIsthly Having taken some Amber and warily distill'd it not with Sand or powder'd Brick or some such additament as Chymists are wont to use for fear it should boylover or break their Vessels but by its self that I might have an unmixed Caput mortuum Having made this Distillation I say and continued it till it had afforded a good proportion of phlegm Spirit Volatile Salt and Oyl the Retort was warily broken and the remaining matter was taken out in a lump which though it had quite lost its colour being burnt quite black and though it were grown strangely brittle in comparison of Amber so that they who believe the vertue of attracting