EXPERIMENTS AND Considerations ABOUT THE Porosity of Bodies, IN TWO ESSAYS.

By the Honourable ROBERT BOYLE, Fellow of the Royal Society.

LONDON, Printed for Sam. Smith at the Prince's Arms in S. Pauls Church-Yard. 1684.

TO THE READER.

THe Reader is to be adver∣tis'd, not to expect in the fol∣lowing Essay a Regular, or so much as a Coherent, Discourse. For it was intended only as a collecti∣on of loose Experiments and Observati∣ons about the Porosity of the parts of Bo∣dies belonging as Chymists speak) to the Animal Kingdom, and laid (not to say thrown (together, in order to what I had thoughts of offering, to∣wards an Intelligible account of Occult Qualities. I am not ignorant, that even one of the most ancient and famous of Physicians hath said, that a mans body is


(almost) every where perspirable. But I judg'd that a Doctrine of such mo∣ment, and which diverse things in the Theory and Practice of after Physicians may make one think they either disbe∣lieved or disregarded, did not deserve to be slightly deliver'd, and in general terms, but to be more narrowly conside∣red, and likewise made out by Particu∣lar Instances, whose applyableness and usefulness to explain divers obscure Phaenomena, may hereafter appear much greater, then perchance at the first sight they will be thought.

And the foregoing advertisement, with a light change, which 'tis presum'd the Reader may easily make of •im∣self, is to be extended to the Essay tacked to this about the Pores of So∣lid Bodies, and so may excuse the ab∣sence of a distinct Preface to it.

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An Essay of the POROUSNESS OF ANIMAL BODIES.
AS the most numerous part of the Pores of Bodies is too minute to be seen, so the Contemplation of them has been thought too inconsiderable to be regarded. But when I consider, how much most of the Qualities of Bo∣dies, and consequently their operati∣ons depend upon the structure of their minute, and singly invisible, par∣ticles, and that to this latent contex∣ture, thē bigness the figure and the collocation of the Intervals and Pores
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do necessarily concur with the Size, Shape and Disposition or contrivance of the substantial parts I cannot but think the Doctrine of the small Pores of Bodies, of no small importance to Natural Philosophy. And I scarce doubt, but if such little things had not escaped the sight of our Illustrious Verulam, he would have afforded a good Porology (if I may so call it) a place, (and perhaps not the lowest nei∣ther,) among his Desiderata.

And, though other imployments and avocations hinder me from at∣tempting to treat of this subject as am∣ply and particularly as it deserveth, or even as I had design'd in a Scheme drawn diverse years since, and seen by some Virtuosi; Yet, not to leave apart of Physicks, that seems to me so curious and important, altogether as unculti∣vated as I found it; I shall present you as many of the Notes I had drawn together about this subject, as I can conveniently (for I do not pretend to do it methodically) reduced to three heads: Whereof the first, which
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will challenge to it self this present es∣say, is the porosity of Animal Bodies, about which I shall not be solicitous to marshal my observations, since they all conspire to shew but this one thing; That the parts of Ani∣mals, especially whilest these are a∣live, are furnished with numerous Pores.

Those parts of the Bodies of Ani∣mals, wherein their porosity may be best shewn seem to be their Mem∣branes or Skins, the Bones, the Flesh, and Coagmentations of Membranes, Flesh and Juices. And therefore it would be proper enough to treat of these Heads distinctly, and give In∣stances of each of them in particular. But yet I think it will be more conve∣nient, to set down in order the princi∣pal Fountains, whence the Porousness of the substances belonging to the Ani∣mal Kingdom (as the Chymists speak) may be derived, and to annex to each of these the Experiments and obser∣vations, upon which I argue from it, and which it will be easy to refer, if
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that be thought fit, to this or that of the parts above mentioned (namely the Membranes, Bones, &c.) whereto they shall (respectively) appear the most properly to belong.

CHAP. I.
THe first thing from which I will deduce the Porosity we have been speaking of, is, the Frame or Constitution of the stable Parts of the Bodies of Animals. For the Bo∣dy of an Animal being not a rude and indigested lump of matter, but a curi∣ous engine, admirably framed and con∣trived for the exercise of several Fun∣ctions as Nutrition, Generation, Sensa∣tion, and many differing local Motions, it was necessary that it should be fur∣nished with variety of Dissimilar and Organical parts not only very Skil∣fully, but very differingly, contrived congruous to the several uses for which they were designed, or if you please, to the several Functions they
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were to perform. And, because 'twill be easily granted, that the Corpuscles, that are skilfully brought together for such purposes, must be so contexed as not to touch one another exactly every where, it will readily follow that they must leave little Intervals or Pores between them, and that, considering the multitude of particles that must go to the making up the Body of the Animal, and the great difference and variety in point of bigness and figure of the Corpuscles that are requisite to contex such differing parts, as Membranes, Fibres Bones, Grizles, Ligaments, Veins, Ar∣terys, Nerves, &c. Both the number and the variety of the Pores cannot but be very great. This argument will be much confirmed, by what there will be occasion to say further to the same purpose, in the Essay touch∣ing the Porosity of even Solid Bodies. Wherefore I shall now proceed to the Second thing, whence we may derive that of Animal Sub∣stances.

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CHAP. II.
THis is afforded us by consider∣ing the Nutrition of Animals. For there being continually a great waste made of their substance, partly by the exclusion of visible excrements, and partly by the avolation of invisi∣bles steam, this great loss must ne∣cessarily from time to time be repair∣paired by the supplies afforded by Nu∣trition of which the best, if not the only Intelligible, way of giving an ac∣count, is, to conceive that the alimental Juice, prepared chiefly in the Stomach is impelled or attracted (for to our present purpose it matters not which) to the parts of the Body that are to be nourished by it, and the Corpuscles of the juice insinuate themselves at those Pores they find commensurate to their Bigness, and Shape; and those that are must congruous, being assimilated, add to the substance of the part wherein
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they settle, and so make amends for the Consumption of those that were lost by that part before. This may be illustrated by what happens in Plants, and especially Trees, in which, of the various Corpuscles that are to be found in the liquors, that moisten the Earth, and are agitated by the heat of the Sun and the Air, those that happen to be commensurate to the Pores of the Root, are by their In∣tervention impelled into it, or imbi∣bed by it, and thence conveyed to the other parts of the Tree in the form of Sap which passing through new strai∣ners, (whereby its Corpuscles are se∣parated, and prepared or fitted to be detained in several parts) receives the alterations requisite to the being turned into Wood, Bark, Leaves, Blos∣soms, Fruit, &c. But to return to Ani∣mals, our argument from their Nutri∣tion will be much confirmed, by con∣sidering, that in Children and in other young Animals, that have not yet at∣tained their due Stature and Bulk, the Nutrition is so copious as to amount
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to a continu'd Augmentation. For, as 'tis evident that Animals grow in all their parts, and each part according to all its Dimensions, in so much that even the cavities of Bones increase; so we cannot well conceive how this can be done, unless the Nutritive liquor be distributed through the whole Bo∣dy of the part that is to be nou∣rished and augmented. And to this distribution 'tis requisite that the Body abound with Pores into which the congruous particles of the Juice may be intimatly admitted, & penetrating even into the innermost recesses, may place or lodge themselves in the man∣ner that is most convenient for the Na∣tural Increase of the part. But the more particular Declaration of this Process I leave to Anatomists and Physicians.

CHAP. III.
HAving premis'd once for all, that in this Essay, I often use the word Skin in the lax and popular sense of it,
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without nicely distinguishing the Epi∣dermis or Cuticula, called in English the Scarf-skin, from the Cutis it invests and sticks closely to; I shall proceed to another Topic, whence the Porous∣ness of Animals may be argued, name∣ly, the great plenty of matter that is daily carried off by Sweat, and insensible Transpiration. For, 'tis con∣fest that Sweat is discharged at the Pores of the skin; and since there is no penetration of Dimensions, we may safely conclude, that the matter that is not wasted by Sweat, or by any o∣ther sensible way of evacuation, must have small Pores or out-lets in the Skin, at which it may issue in the form of steams; though nothing hinders but that invisible Effluvia also may evapo∣rate at the same Pores with the Sweat, though for want of plenty or grossness, or a fit disposition in the ambient, those Effluvia be not at the Orifices of those Pores brought into little Drops, such as those of sweat.

That therefore the Skins of a mul∣titude of Animals, though they seem
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close to the eye, may be porous, may (as we have been saying) be argued in many of them from their sweating. But because all of them have not been observed to sweat, as is wont to be particularly affirmed of Dogs, we shall add some other Instances to make it probable.

We may sometimes, in the smooth skin of a living man, discern Pores with good Microscopes, and, with one that is none of the best, we may easily on the inside of gloves, which are made but of skins drest, discern good store of these little out-lets: Some∣times orderly enough ranged to make the sight not unpleasant. And though some of them may, I think, be su∣spected to have been made by the Hairs that grew on the skin before 'twas drest, yet that greater numbers of them, than can be supposed to come from thence, are perforations that pass quite through the Leather, may, not improbably, be shewn by the usual Practice of Chymists, to purify Quick-silver by tying it up strictly
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in a piece of kids or sheeps Leather, and then wringing it hard to force it out; by which means the lower surface of the Leather will be covered with a Mercurial Dew or Sweat which will fall down and fly out, as the Pores happen to open this or that way, in a thick shower of globules, leaving the dross behind in the Leather. And tho when a mans skin is tanned it is of a greater thickness then one would expect, and that which I employed seem'd almost as thick as a Buck-skin Glove yet having had the curiosity to try the same Experiment with the skin of a mans Arm, I found the Quick-Sil∣ver would be squeez'd out at the Pores of that also. 'Tis not necessary that I should here inquire, whether the lit∣tle holes, unperceiv'd by the naked Eye, at which the Sweat is discharged, and perhaps the matter that the Body looses by insensible transpiration gets out, be not, at least most of them, the Orifices of small excretory vessels, belonging to those very numerous glandules which the excellent Anato∣mists
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Steno and Malpighi are said to have discovered beneath the Cuticula, and which for their smalness and shape have been called Glandulae miliares. I need not, I say, engage in this inquiry, since according to this ingenious opi∣nion also, the Skin must be allow'd a multitude of small Perforations or Pores, and that is sufficient for my pur∣pose, from whencesoever this Porosity proceeds in a mans Skin. For the next observation will shew that some mem∣branes of Animals may give passage to transpir'd matter without being perfo∣rated by the excretou• Vessels of Glan∣dules.

The Membranes or Skins under the shells of Hens Eggs, though they be very thin, are of a Contexture very fine and close as may be confirmed by their resisting the sharp Corpuscles of Vinegar; and yet, that not only these Skins, but the shells that cover them, are porous, may be inferred from the Experiments I made, of keeping them suspended for a good while, and care∣fully counterpoised in good scales;
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for by these it appeared, that the Eggs did from time to time manifestly lose in weight; which could not reasonably be imputed but to an invisible Tran∣spiration, the rather, because usually in eggs that have been kept long, there will be at one end a cavity which is wont to increase with their age, and is made by the shrinking of the Membrane from the Shell, to ac∣commodate it self to the diminished quantity of matter, that remains to be involved by it.

When I consider the plenty of mat∣ter, that is wont to be discharged dai∣ly by insensible Perspiration, especial∣ly in Healthful men that exercise them∣selves moderately, I cannot but think it probable, that the minute Pores, that suffice for the carrying off so much matter, are very numerous, and are much more so than even by the multitude of drops of sweat, that serve to wet the skin, men are wont to imagine. For Sanctorius in his ex∣cellent little Tract de Medicina stati∣ca affirms, that what is barely car∣ryed
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off by insensible transpiration does ordinarily amount to more, that is, diminishes more the weight of a mans Body, than all the visible ex∣crements (whether gross or liquid) put together. Aph. vi. He adds, If the meat and Drink, taken in one day, a∣mount to the weight of eight pound, the insensible Transpiration ordinarily amounts to five pounds or thereabouts. And elsewhere says, that sometimes in the space of 24 hours, in the Win∣ter time, a healthy Body may ex∣hale fifty ounces or more. And some Tryals, that I have carefully made up∣on my self, added to some others of a very curious as well as great Prince, that made use of a like instrument, & did me the honour to acquaint me with the events, gave me no cause to reject Sanctorius observations, considering the difference in point of heat, between the climate of Italy, where he writ, and that of England, where ours were made; only I fear, there has been com∣mitted an oversight by those many that ascribe all the decrement of
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weight, that is not referrable to the grosser Excrements, to what transpires at the Pores of the visible parts of the skin, without taking notice of that great plenty of steams that is in expi∣rations discharged through the Wind∣pipe by the Lungs, and appear manifest to the Eye it self in frosty weather; though they may be presumed to be then less copious than those Invisible ones that are emitted in Summer, when the ambient Air is much war∣mer. But though I look upon the Wind∣pipe as the great Chimney of the Bo∣dy in comparison of those little Chimneys (if I may so call them) in the Skin, at which the matter that is wasted by perspiration is emitted, yet the number of these little vents is so very great, that the fuliginous Ex∣halations that steal out at them, can∣not but be very considerable. Besides that, those that are discharged at the Aspera Arteria, do probably, at least for the most part, issue out at the la∣tent Pores of the Membranes that in∣vest the Lungs; which membranes
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may be lookt upon as external parts of the Body, in reference to the air, tho not in reference to our sight. But, to return to our Eggs, we may safely al∣low a very great evacuation to be made at the Pores of the skin in man, who is a sanguineous and hot Ani∣mal, since we see that even Eggs, that are still actually cold, transpire. And I elsewhere mention the copious transpi∣ration even of Frogs, that are always cold to the touch; and the Decrement in weight of some Animals, soon after they are strangled or suffocated, when, their vital Heat being extinct, no more fumes are emitted by expirations at the wind-Pipe: To which signs may be added the trivial experiment of holding in warm weather the palp of ones Finger, as near as one can without contact, to some cold & solid smooth body, as to a piece of polish∣ed Steel or Silver; for you will often times see this Body presently sullyed or overcast, with the invisible steams that issue out of the Pores of the Fin∣ger, and are by the cold and smooth
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surface of the Body condensed in∣to visible steams, that do as 'twere cloud that surface, but upon the Removal of the Finger, quickly fly off, and leave it bright again.

The Perviousness of the skin out∣wards may not improbably be argued from the quickness wherewith some Medicines take away some black and blew Discolorations of the skin, that happen upon some lighter stroke, or other contusions. For, since these pre∣ternatural and unsightly colours are wont by Physicians to be imputed to some small portions of blood, that upon the contusion is forced out of the capillary vessels that lye beneath the surface of it, & being extravasated are obliged to stagnate there; it seems very likely, that if a powerful Medi∣cine do quickly remove the discolora∣tion, that work is performed by attenu∣ating, and dissolving, and agitating the matter, and disposing it to transpire through the cutaneous Pores, though perhaps, when 'tis thus changed, some part of it may be imbibed again by
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the Capillary Vessels, and so by the circulation carryed into the mass of Blood. Now, that there are Medicines that will speedily work upon such black and blew marks, the Books and Practice of Physicians and Chirurge∣ons will oblige us to admit. Helmont talks much of the great vertue of white Briony root in such cases. And a no∣table Experiment made a while ago by a Learned acquaintance of mine in an odd case, did not give Hel∣mont the Lye. And I know an emi∣nent Person, who having some while since received a stroke, by a kick of an Horse, on his Leg, a very threat∣ning contusion, which made the part look black and frightful, he was in a few hours cured of the pain of the hurt, and freed from the black part of the Discoloration by the bare ap∣plication of the chopt leaves of Hissop mixt with fresh Butter into the form of a Pultess.

Nor is it only the Skin that covers the visible parts of the Body that we judg to be thus porous, but in the Mem∣branes
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that invest the internal parts, we may reasonably suppose both nu∣merous and very various Pores, ac∣cording to the exigency of their pe∣culiar and different Functions or Offi∣ces. For, the two first causes of Poro∣sity mention'd in this Essay, are as well applicable to the Membranes that cover the internal parts, as the Liver, the Spleen, &c. as to the exter∣nal Skin, or Membrane that covers the Limbs; and in some respects the transpiration through such Pores seems more advantaged, than that through the Pores of the surface of the Body; since the parts that environ the Spleen, Liver, Kidneys, &c. in man, are hot in comparison of the ambient Air, and being also wet, which the Air is not, the laxity of the Pores of the internal parts is doubly befriended. And perhaps it may be allowable to conceive, both the Skin that covers the Limbs, and the Mem∣branes that invest the internal parts of the Body, to be like worsted stock∣ings, Wast-Coats, &c. Which in their
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ordinary state have a kind of continu∣ity, but upon occasion can have their Pores every way enlarged and stretch∣ed, in this or that manner, as the A∣gents that work on them determine them to be. This may be confirmed, by what we manifestly see in the fi∣ner sort of leather, as that of Kid or Lamb, and by the latent Pores that may be opened in Sheeps-Leather, and mans Leather, by the pressure of in∣cluded Quick-Silver.

This Porosity of a living mans Skin and other Membranes, though inter∣nal ones, will the more easily be assen∣ted to if it appear that such thick and gross Membranes, as the urinary blad∣ders of dead Animals, are Porous and Penetrable even by Water. This we tryed, by putting some salt of Tartar in a clean well dryed bladder (which ought to be afterwards tyed up close in the neck, lest the effect should be ascribed to the moist Air) and leaving the lower part of the blad∣der, as far as the Salt, reached immer∣sed in common Water, whose parti∣cles
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by degrees insinuated themselves into the Pores of the bladder, in plenty enough to resolve the Salt of Tartar into a liquor. And, that it may not be said that the Acrimony of the Salt, by fretting the bladder, made way for the Corpuscles of the Water, I shall add that the Experiment suc∣ceeded, but much more slowly, when we tryed it with Sugar instead of Salt of Tartar. And there are some, who pretend that certain Sy∣rups made this slovenly way, which they would have pass for a secret, are very much preferable to those made of common Water.

That the films that line the shells of Eggs are of a very close Contexture seems probable, as by other things, so by their resisting some liquors, sharp enough to corrode the shell, and yet that such Membranes are pervious to Liquors that are none of the most sub∣tile of all, we found by the ensuing Ex∣periment. This was made by taking an ordinary Hens Egg, and keeping it for two or three days in distill'd Vinegar,
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or in strong crude Vinegar. For then taking it out of the Liquor and wiping it well, it was visibly, and not incon∣siderably, swell'd, which I concluded to be from the ingress of some parti∣cles of the liquors, at the Pores of the Skins that invest the White of the Egg. For we found nothing broken, though we made the Tryal more than once. And to be satisfied that the manifest expansion proceeded from some other cause, than the meer dilata∣tion of the White, or Yolk, or both, we compared the weight of the Egg, af∣ter it was taken out and well wiped, with that which had been taken be∣fore 'twas put into the Menstruum, and found the Egg, notwithstanding the loss of the Shell, to be considerably heavier than 'twas before its immer∣sion.

I shall add on this occasion that by a more unlikely way than that newly recited, both the Egg, Shell and Lining of an Egg, may be penetrated. For, not∣withstanding the fine and close con∣texture of the Membranes that invest
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the Eggs, the Chineses have a way of Salting them in the shell, as I have been assured both by English and Dutch Merchants trading to the East Indies. And in one of the Dutch Jour∣nals sent by the Council of Batavia to their Principals in Holland, and in∣tercepted by an English man of War, I met with divers accounts of great numbers of salted Eggs, that were such or such a day of such a Month brought in by Sea to Batavia or other Ports. Long after which time, meet∣ing with an ingenious Physician, that liv'd in Batavia, I learned by enquiry from him, that 'tis very true that such Eggs are frequently met with in those parts; he having divers times eaten of them there: some that he judged to have been either boyled or roasted, before they were salted; and others that were raw, when they came to be dressed for him, but yet retained a Briny tast. And, though the Mer∣chants I enquired of could not tell me what way the Chineses employed to Salt their Eggs, without making them
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unfit for common use, yet by a tryal made with clay and Brine, in which I kept the Eggs for a competent time, I was perswaded that 'twas possible the Chineses should have the Art ascribed to them. For upon the breaking of an Egg coated with clay, after it had lain for a competent time in Brine, I found its Tast considerably Salt, but was, by I know not what accident, hindered from prosecuting the Experiment, and endeavouring to make it more practi∣cable and useful.

I knew a Physitian of more lear∣ning than vertue, who, being tormen∣ted with a violent and obstinate Colic of a peculiar kind, was wont to re∣lieve himself by Clisters of Sack; thô he usually found that not long after he had taken any of them, they would make him giddy, and fuddle him, as he himself confessed to me. But upon this Instance I lay not much weight, and less upon what was answered me by a great Chirur∣geon, who having practised his Art in the West-Indies, and being asked
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by me whether he had not dressed Wounds and Ulcers with the recent juice of Tobacco (a plant I use to keep growing in my Garden for its excel∣lent vertues in cuts, burns, and tumors;) and whether, if he employed it, he did not find it emetick, he told me among other things, that having Di∣vers times dressed with this Juice a small Ulcer in a Womans leg, the pa∣tient soon after the application would grow sick, and have her stomack tur∣ned, or actually vomit. But, as I was saying, on this instance I lay no stress, because the Corpuscles of the Tobacco might probably enough get in at the small Orifices of some corroded Ves∣sels, and so be conveyed inwards, ra∣ther by the help of the Circulation of the blood, than on the account of the Porousness of the Parts. And therefore I shall rather mention what has been related to me, by an eminent Phy∣sician of the famous Colledge of Lon∣don, namely, that he had divers times given himself a vomit, by a certain application of decocted Tobacco to
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his wrists, and some other external parts; which brings into my mind, what is affirmed to have been obser∣ved in some Children that have scabb'd Heads, who have been made Drunk, by the application of Clothes or spun∣ges wetted in Infusion of Tobacco, or of strong Liquors, and applied to the part affected. Though in this case the inebriating Particles may be suspected to have got in, not at the meer Pores, but rather at the Orifices of the Capil∣lary Vessels, that were made accessible by such little solutions of Continui∣ty, as are seldom wanting in scabbed Heads.

That Children may be purged by outward applications is asserted by some Physicians; and an experienced Person of that number has affirmed to me, that he can almost constantly do it by a Plaister. But 'tis more con∣siderable what was related to me by an eminent Virtuoso, who being in∣disposed to believe such things a while before he told me the story, was de∣sired by a curious Person to shew him
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his Hand which the Relator having done the other took it in his hand, which was moistened (as was after∣wards confessed) with a kind of sub∣tile Chymical Oil, but so slightly, that the Relator scarce minded it, till some time after when he found himself prest with a motion, like that which a purge would have given him; for the other thereupon smiling, my acquaintance began to suspect what the matter might be, and was in a short time purged four times, without griping, or other pain or discomposure. But to re∣turn to the Porousness of Membranes, it may serve to make way for your admitting it, to observe, that though Lute-strings be but Ropes of Fibres (which are at least the chief parts that Membranes consist of) dead, cold and stiff, yet when the lute is in tune they will sometimes in wet weather swell so forcibly as with noise and violence to break, which proceeds from the copi∣ous ingress of moist vapors into their Pores, whereby they are not only shortened, but as I have tryed in
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nice scales, made manifestly heavier.

The Porosity of the internal parts of Animals by both the foremention'd ways (viz. of emission and reception of Corpuscles,) may be confirmed by the things that happen in some of the Metastases or Translations (as the Physitians call them) of the morbifick matter in diseased Bodies. 'Tis known to them that are any thing conversant with Hospitals, or the observations of Physicians, that there do not seldom occur in Diseases sudden Removes of the matter that caused them, from one part to another according to the na∣ture and functions of which, there may emerge a new Disease, more or less dangerous than the former, as the invaded part is more or less noble. Thus oftentimes the matter, which in the sanguiferous Vessels produced a Feaver, being discharged upon some internal parts of the Head, produces a Delirium or Phrenitis; in the latter of which I have somewhat wondered, to see the Patients Water so like that of a Person without a Feaver; the same
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Febrile matter either by a deviation of Nature, or medicines improper or unskillfully given, is discharged some∣times upon the Pleura, or Membrane that lines the sides of the Chest; some∣times upon the throat; sometimes up∣on the Guts; and causes in the first case a Pleurisie, in the 2d a Squinancy, and in the third a Flux, for the most part dysenterical. But, because I suppose, that many, if not most, of these trans∣lations of peccant humors, are made by the help of the circulation of the Blood, I forbore at the beginning of this Section to speak in general terms, when I mentioned them in reference to the Porousness of the internal parts of the Body, and contented my self to intimate, that some of them may serve to confirm that Porosity.

This will not perhaps seem impro∣bable, if we consider that 'tis in effect already proved, by the same argu∣ments by which we have shewn, that both the Skin and the internal Mem∣branes are furnished with Pores, Per∣meable by Particles whose Shape and
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Size are correspondent to them. For we may thence probably deduce, that when a morbifick matter, whether in the form of Liquor, or of exha∣lations, chances to have Corpuscles suited to the Pores of this or that part of the Body, it may, by a concourse of Circumstances, be determined to in∣vade it, and so dislodge from its for∣mer receptacle, and excite Disorders in the part it removes to.

CHAP. IV.
ANother thing whence the Po∣rosity of Animals may be ar∣gued▪ is, their taking in of Effluvia from without. For these cannot get into the internal parts of the Body, to perform their operations there, with∣out penetrating the Skin, and conse∣quently entring the Pores of it.

Now, That things, outwardly apply∣ed to the Body, may without wound∣ing the Skin, be convey'd to the inter∣nal parts, there are many things that argue.

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And first, it has been observed in some Persons, (for all are not equal∣ly disposed to admit the action of par∣ticular Poysons) that Cantharides, be∣ing externally apply'd by Chyrurgions or Physicians, may soon, and before they break the Skin, produce great disorders in the Urinary Passages, and sometimes cause bloody Water. And I remember, that having once had a blistering Plaister, applyed by a skil∣ful Chyrurgion between my shoulders, though I knew not that there were any Cantharides at all mixt with the other Ingredients, yet it gave me about the neck of my Bladder one of the sensiblest pains I had ever felt, and forced me to send for help at a very unseasonable time of night.

The Porousness of the Skin may be also argued from divers of the ef∣fects even of Milder Plaisters. For, though some Plaisters may operate as they closely stick to the Skin, and hinder Perspiration from within, and fence the part from the external cold; yet, twill scarce be denied, that
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many of them have notable effects up∣on other accounts, whereof none is so likely and considerable as the copi∣ous ingress of the Corpuscles of the Plaister, that enter at the Pores of the Skin, and being once got in, act ac∣cording to their respective Natures & Vertues. The like may be said of Ointments, whose operations, especi∣ally on Children (whose Skin is ordinarily more soft and lax) are sometimes very notable. And I have known considerable things performed by them, in an internal Disease of grown men, where I should scarce have expected a Vegetable Ointment should perform so much: I say, a Ve∣getable Ointment, for 'tis vulgarly known that by Mercurial Ointments Salivation may be excited; and some∣times, against the Physitians will, the Corpuscles of the Quick Silver get so far into the Body, that he is not able to get them out again.

What we lately said of Plaisters, may be applyed to those that Physi∣tians call Pericarpia, or Wrist-bands:
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The better sort of which, though sometimes ineffectual, are oftentimes successful in stopping Fits of Agues, as I have frequently found in a mixture, elsewhere mention'd, of Currans, Hops, Baysalt well beaten together, by which, by Gods blessing, many, and I among others, have been freed from simple Tertians, and either double Ter∣tians or Quotidians.

The Argument of the Porosity of Animals, drawn from those things that get in through their skins, without breaking or wounding them, may be much strengthned, if it can be made appear, that those Physitians do not deceive us, who ascribe sensi∣ble Operations and Vertues, to things externally applyed, in so loose a way, that they do not so much as stick to the Skin, or perhaps immediately touch it; such as some call Periapta and Appensa; divers of which are best known among us, by the name of Amulets; such as are the Quills con∣taining Quick-silver or Arsenick, that some hang about their necks, and
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wear under their Shirts, against the Plague and other Contagious Dis∣eases; and the Bloodstones that others wear against Haemorrhages; and the stone which the Women use in the East-Indies, for a quite contrary effect, in Obstructione Mensium. That many of these external Medicines, answer not the promises of those that extol them, having some of them no sen∣sible operation at all, and others no considerable one, experience has as∣sured judicious observers; but that some of them, especially on some Patients, may have considerable, not to say admirable, operations, I confess my self by other motives, as well as Authority, to be perswaded. Hav∣ing been one summer frequently sub∣ject to bleed at the Nose, and reduced to imploy several remedies to check that distemper; that which I found the most effectual to stanch the blood, was some moss of a dead mans Scull (sent for a present out of Ireland where 'tis far less rare than in most other Countrys) though it did but
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touch my skin till the herb was a little warm'd by it. And though I remember not that I have known any great matter done to stop Haemorrha∣gies by the bare outward application of other Blood-stones; yet of one that look'd almost like an Agate, I admired the effects, especially upon a young and extraordinarily Sanguin person. To which I shall add a memorable thing,* communicated to the experienced Zwelfer by the chief Physitian of the States of Moravia. For this learned man whom he extols for a great Physician and Philosopher; assures him, that having prepared some Trochischs of Toads according to Helmonts way, (which I remember I also was solici∣tous to prepare, but had not occasion to make tryal of their vertue,) he not only found, that being worn as Amu∣lets they preserved him and all his Domesticks, and Friends, from the Plague (though he daily visited the infected) but that having caused these
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Trochischs to be put upon the Plague sores of several persons, none of them died, but the venom of the pestilential Carbuncles was thereby so weakened that the ulcers were afterward easily cured by vulgar remedies.

And now, as to the difficulty, which I acknowledge not to be small, to conceive how Bodies actually cold can emit Effluvia, capable of pene∣trating (without moistening it) a Membrane of so close a Contexture as a mans Skin; I suppose it will be much lessened in the objectors opinion, by what he will meet with hereafter about the Pores of Bodies, and the Figures of Corpuscles. For supposing these to be congruous, it will not seem incredible, that the Effluvia of Amu∣lets should in tract of time get passage through the Pores of the Skin of a Living Body. And to make this the more probable, I will give an Instance in the Skin of a dead Animal. And, because this requires a Liquor I much employ in these trials about Porology, though I have many years since in
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another Tract taught how to make it for another purpose; yet I shall here repeat, that 'tis made by exactly ming∣ling Flower of Brimstone, powdered Sal Armoniac and good Quicklime in equal quantities, save that, if the Quicklime be not very dry and good, a fourth or fifth part must be super∣added, for these being nimbly mixed, and distilled by degrees of Fire in a Retort, till the Sand be at length brought to be almost red hot, there will come over a smoaking Spirit, which must be kept very carefully stopt, and which for distinctions sake, I also use to call, The Permeating Menstruum or Liquor, and its expi∣rations the Penetrant, or Permeating Fumes.

And now you will easily under∣stand the experiment I was about to mention, which was this; We took a very clean piece of polish'd Copper, in want of which one of silver will serve the turn, and having lapt it up in a piece of either Lambs or sheeps Leather, so that it was every way
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inclosed, we then held it over the Orifice of the Vial that contained the Spirit, at a pretty distance from the Liquor, whose fumes nevertheless did quickly, (perhaps in a minute of an hour or less) pervade the Pores of the Leather, and operate upon the inclu∣ded metal as appeared by the deep and lasting tincture it had given to the lower surface of it, though the interposed Leather it self was not deprived of its whiteness, nor at all sen∣sibly discoloured; however it smelt of the Sulplureous steams that had in∣vaded it. And, if I misremember not, the same Experiment succeeded, though somewhat more slowly, when a double Leather was interposed between the fumes and a new piece of Copper coin. This will be thought the less strange, when I shall come to some other Instances of the Penetrancy of these Spirits. In the mean while I leave it to be considered, whether this may not suggest some conjecture at that strange Phoenomenon, which is recorded by Authors of good repute,
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That sometimes in great Thunders the Lightening, among other opera∣tions, has been found to have mani∣festly discoloured mens money, with∣out burning the Purses or Pockets wherein it lay. For in our experiment, the steams that in a trice pervaded the Leather, the most usual matter where∣of Purses are made, were sulphureous, as the smell argues, that those which accompany the Fulmen are wont to be; and whereas these, when they invade Bodies, are usually very hot, ours operated when the Liquor that emitted them was actually cold. And if it be said, that sometimes their mo∣ney has been found discolored in their Pockets, who were not struck, by the Fulmen, but had it only pass near them, it may be objected, that tho the intire Body, whether fluid or so∣lid, if there be any of this latter kind that is in Latine called Fulmen (for our English word, Thunderbolt seems not so applicable to a fluid) did not touch them, yet it might scatter steams enough round about it, to cause
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the Phoenomenon. For confirmation of which I shall take notice, that a con∣siderable Person of my acquaintance, having had the Curiosity to ascend a burning mountain in America, till the sulphureous steams grew too offensive to him, he told me that, among other operations he observed them to have upon him, one was, that he found the money he had about him turned of a black and dirty colour, such as I have observed our sulphureous steams of∣ten give both to Copper, and to Silver Coins. But whether or no our Spirits will justify the conjecture, they invi∣ted me to mention, at least their so ea∣sily pervading the Skin of a dead Ani∣mal may make it probable, that the Skin of a Living man may be easily pe∣netrated by external steams whose ap∣proach the Eye does not perceive, and whose operations, though not inconsi∣derable, may therefore be unsuspected. I leave to Physitians to consider, what use may be made of this observation, in reference to the propagation of contagious Diseases, by the contact of
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infected Air, distinct from the Respi∣ration of it, and by the penetration of the steams, that issuing from divers Bodies invade the Skin, and may perhaps be capable of operations, either hurtful or friendly, that are not usually suspected to proceed from such causes, and are therefore misa∣scribed to others. And on this occasion it will not be impertinent to add, that by hanging up sheeps Leather or Lambs Leather in the free Air, the vapors of it would so insinuate themselves into the Pores in wet weather, that a moderate degree of moisture in the Air would add to it a not inconsiderable weight, of which dry weather, whether hot or cold, would deprive it.

CHAP. V.
I Must not in this place omit some Instances, very proper to mani∣fest the Penetrableness of Membranes to Fumes themselves, if they be subtile
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enough for their Pores, or correspon∣dent enough to them.

Among the observations published by Physicians I have met with some by which it appears that Cantharides may have great Effects upon the in∣ternal Parts of the Body, though they do not so much as touch the Skin, but are placed at some distance from it,* so that their Effluvia must be tran∣smitted through other Bo∣dies before they can pene∣trate that. The learned Michael Paschalius menti∣ons a Chyrurgion, who was twice brought to void much Blood with his Urine, by some Spanish Flies that he carryed about in a Purse or Bag. And another Doctor of note relates of another person that came to complain to him, that he pissed Blood, having carryed about with him Cantharides, though in his Pocket, and adds, that a like Case was recounted to him by Helidaeus, whom he calls an eminent Bolognian Physician.

We see, that in Linnen Cloth, the
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finer and more slender the threads are the closer and less Porous, coeteris paribus, the Linnen is: By analogy to which one may esteem the thin film that lines the shell of an Egg, to be of an exceeding close Contexture; and yet that even this film is not imper∣vious to some Fumes, I have found by the following Tryal.

To make this, we slowly and warily pick'd off a sufficient part of the Shell of a Hens Egg, from the Skin that lay just beneath it, and is wont to stick so close to it, that their separation, without injuring the Membrane, is not easy. In this Skin, being wip'd, we wrapt up a flat piece of Copper, whose surface was made bright, that the change of Colour might be the better seen; and having kept this covered bit of Plate, over the Fumes of our smoaking Li∣quor lately mentioned for a minute or two by our ghess we unfolded the Skin, and found, as we expected, that the lower surface of the Copper which was it that had been held over the
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Fumes, was turned of a very dark co∣lour, which manifested that even so fine and closely contexed a Mem∣brane was not only, as we have for∣merly shewn, penetrable by Li∣quors, but readily pervious to our sulphureous exhalations, tho these were probably but faintly emitted, since the Liquor they came from was then actually cold. But in making the Tryal it is fit to hold (as we did in that newly recited) the Mem∣brane against the light, to see if it be intire, and have escaped all those little lacerations that are hardly avoidable in severing it from the Shell it sticks so close to. If this caution be neg∣lected, 'tis easy to be imposed on, by overlooking some little holes, that are not easily discerned when one looks down upon the Skin, and yet may be sufficient to make the Expe∣riment deceitful. But, thô when 'tis well made, it is a notable confirmation of the Doctrine endeavoured to be established in this Paper, yet I shall now subjoyn a more considerable
Page 45

Instance to the same purpose.

The Porousness of the Internal Membranes of the Body, will be more easily granted, if it be considered that either the Liquors, or the moist Exhalations, whose Action is pro∣moted by the Natural Heat of the Parts, keeps them constantly wet or moist, and thereby renders them more lax, and more penetrable by subtle Spirits or other Corpuscles. In favour of this Reflection I made the follow∣ing Experiment. We took a piece of a dryed Urinary Bladder, which was judged to have been a Calfs; and having lapt it about a new piece of Silver Coin, so that the Bladder was single where it covered the lower side of the Piece, we kept it for divers Minutes, by guess, over the Spirituous Fumes of our often mentioned Per∣meating Liquor, but could not per∣ceive that the Coin was thereby at all affected or ternished. Whence we concluded that the Pores of the dry Bladder were too close and narrow▪ to give passage to the Expirations of
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the Menstruum. But presuming that moisture would some what relax them with another piece of the same Bladder, made limber by being a little wetted in common Water, we lapt up another like peace of new Coin, as we had done the former, and kept it at the same distance as before, from the Liquor, but not for so long a time. For after about two Minutes, by guess, we remov'd and took out the Piece, and, as we ex∣pected, found much of its lower sur∣face (that regarded the Liquor) deeply discoloured. Which Experi∣ment will not only justify what I lately said, of the greater Laxity of moist than of dry Membranes, but will be thought no mean confirma∣tion of what is in this Essay delivered about the Porosity of Membranes, since the Urinary Bladder does, as Anatomists well know, consist of more than one Membrane, though they stick so close together, as to ap∣pear but one to the Eye. And this Bladder was speedily penetrated by
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the Fumes that our Liquor emitted in exceeding Cold and Frosty weather, though the Bladder it self was not in the warm Body of the live Animal, but had been so long kept dryed and cold, that probably the Moisture it in∣troduced in scarce one minute of an Hour, could not restore it to the Laxity it had, whilst it was a part of the living Calf.

One of the notablest Instances I ever met with, of the Porosity of the In∣ternal Membranes of the Humane Body, was afforded me by that British Nobleman, of whom our fa∣mous Harvey tells a memorable, not to say matchless, story. This Gen∣tleman, having in his youth, by an accident which that Doctor relates, had a great and lasting Perforation made in his Thorax, at which the motion of his Heart could be directly perceiv'd did not only out live the accident, but grew a strong, and somewhat corpulent man; and so robust, as well as Gallant, that he afterwards was a Souldier, and had
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the honour to command a Body of an Army for the King. This Earl of Mount-Alexander (for that was his last Title having mar∣ryed one of my nearest kinswomen, and having been told that I was very desirous to see, what I had heard such strange things of, very obliging∣ly came, at a fit time, to give me that satisfaction. In order to which he removed that which covered the wide Orifice of his Hurt, and gave me the opportunity of looking into his Thorax, and of discerning there the motions of the Cone, as they call it, or Mucro of the Heart. But these things I mention but upon the by, and be∣cause of the strangeness of the fact; the thing I principally intended relates to my present argument. Having then made several inquiries fit for my pur∣pose, his Lordship told me, that when he did, as he was wont to do from time to time, (though not every day) inject with a Syringe some actually warm medicated Liquor into his Thorax, to cleanse and cherish the
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Parts, he should quickly and plainly find in his Mouth the tast and smell of the Drugs, wherewith the Liquor had been impregnated. And I further learned, that, whereas he constantly wore upon the unclosed part of his Chest, a Silken Quilt, stuffed with Aromatick and odorife∣rous Powders, to defend the neigh∣bouring Parts and keep them warm; when he came, as he used to do after some weeks, to imploy a new Quilt, the fragrant Effluvia of it would min∣gle with his breath in exspiration, and very sensibly perfume it, not, as I declared I suspected, upon the score of the pleasing Exhalations that might get up between his Clothes and his Body, but that got into the Organs of Respiration, and came out with his Breath at his Mouth, as was confirmed to me by a grave & judicious States∣man, that happened to be then pre∣sent, and knew this General very well. Other circumstances I might add, but that I dare not trust my memory for them, and unhappily lost the Paper,
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wherein the oddness of the things in∣vited me to set them down, for fear of forgetting them.

That part of this Narrative which relates to Injections may be much confirm'd by what is delivered by Galen himself, who says that Mulsum or Honeyed Water, being injected at the Orifice of Wounds penetrating into the cavity of the Thorax, has been observed to be in part received into the Lungs, and discharged out of the Aspera Arteria by coughing. And this he mentions as a known thing, imploying it as a Medium whereby to prove another.

The mention that has been made of the Porosity of Membranes, brings into my mind what I once observed at the Dissection, made by some Phy∣sicians, and Anatomists, of a lusty Souldier, that was hanged for I know not what crime. This man, though otherwise young and sound, was observed to have been long molested with what they call a short, dry Cough, which made us expect to find some∣thing
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much amiss in his Lungs. But meeting with nothing there, we were at a loss for the cause of this Cough, till coming to consider the internal part of the Chest, we perceived some∣thing on one of the sides, by tracing of which we discovered, that between the Pleura and the substance of the intercostal muscles, there was lodged a certain matter, of the breadth of a Silver Crown piece, or thereabouts, of a roundish figure, and of the con∣sistence and almost colour of new, soft Cheese, which odd stuff was con∣cluded to have been the remains of some ill cured Pleurisy, and to have transmitted through the Pores of the Pleura, though that be a very close Membrane, some noxious Effluvia, which ever and anon irrita∣ted the Lungs into an irregular and troublesom motion, and so produced the Cough the Malefactor had been molested with.

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CHAP. VI.
I Am well aware that 'tis far less difficult, to prove the permeable∣ness of single Membranes, than that of such a Part of the Body, as seems to be an aggregate of several parts, which in regard of their close adhesion, are looked upon but as one part, to which, on that account, men common∣ly give a distinct name. But yet there are some Phaenomena that seem to ar∣gue, that even such compounded or re∣sulting parts if I may so call them, are not destitute of Pores, which whether they be not some of them the Orifices of exceeding slender and therefore unobserved Capillary Ves∣sels, I must not now stay to enquire.

When the cavity of the Abdomen in those Hydropical Persons that are troubled with an Ascites, is filled with Water, or rather with a Liquor that I have found to be much more viscous, it justly appears strange, that by an
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Hydragogue, or some appropriated purging medicine, great quantities of this gross Liquor should in a short time be carryed off by Siege, and per∣haps also by Urine, though to get into the cavity of the Guts, or that of either of the Kidneys, it seems neces∣sary that it Permeate the Tunicles, and other component parts, of the Viscera it gets into.

I know not whether I may on this occasion take notice of what Physici∣ans observe to occur now and then in Empyema's that follow ill condition∣ed Pleurisies. For it has several times been observed, that upon the bursting of such imposthumes into the cavity of the Chest, the Purulent matter hath been voided by Siege and Urine. I he∣sitate, as I was saying, whether I should alledge this Phaenomenon, as a proof of what I now contend for, till it be de∣termined whether this Metastasis be made by transudation properly so called, or by the ingress of the Pus into the imperfectly closed Orifices of the Vessels of the Lungs;
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where being once admitted and min∣gled with the Blood they may with this circulating Liquor arrive at the Kidneys, or any other Parts fitted to make a secretion of this Heterogeneous matter.

But whatever be the Reason or manner of it, we find that the Lungs do sometimes odly convey things to distant parts of the Body. And if I may here mention a thing, cui honos praefa∣tionis est, I shall add that I have seve∣ral times observ'd in my self, that when I had been an actor or an assistant in the Dissection of a living Dog, es∣pecially if his Blood or Body were rankly Scented, I should divers hours after plainly find that odour in the ex∣crements I voided by Siege.

A famous Chirurgeon and Anato∣mist relates, that one who was very ill of a dropsy, judged to arise from a Scirrhus of the Spleen, coming to ask his counsel and assistance, though he judged the patients case desperate, yet to content him, he ordered him to dip a very large Sponge in good Quick∣lime-Water,
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and having squeezed out the superfluous Liquor, to bind it upon the region of the Spleen, only shifting it from time to time. He adds, that after some months he was much surprized to receive a visit from this Patient, with solemn thanks for his recovery; the outward Medicine having, it seems, resolved the Scirrhus and concurred with nature to evacuate the hydropical humour. For the re∣solution of which hard tumour it seems necessary, that the sanative Cor∣puscles of the external remedy should at length penetrate, not only the Epidermis, and the true Cutis, but the Muscles themselves of the Abdo∣men, and some other interposed parts.

These instances may be strengthen'd by an eminent observation of Galen, who takes notice that Bones being sometimes broken, without piercing the Skin that covers the part they be∣long to, when the Callus is making, and the broken parts of the Bone begin to be conglutinated together, a Portion
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of that Blood which had flowed to the part affected is carryed to the Skin and permeats that, so as to wet and foul the Dressings or Bandages that are kept upon the limb affected by the Fracture.

CHAP. VII.
BOnes, Horns, and parts of the like Substance, being those that are granted to be the most solid of the Bodies of Animals, I come in the last place to shew by particular Experi∣ments that these also have their Pores. I say, by particular Experiments, be∣cause in a general way, their Porosity has been already proved, by the same Arguments, from their original Tex∣ture, Nutrition, Augmentation, &c. That have been employed to manifest the Porousness of Animal substances in general.

That the Nails of men, as well as their Skins, are Porous, may be gathered from their being easily and
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permanently tinged with divers me∣talline solutions, and particularly with those of silver in Aquafortis, and Gold in Aqua Regia; the former of which solutions though cold, will but too easily tinge the Skin and Nails it chances to touch, and makes some little stay upon, with a dark and blackish colour; which I found not that I could wash out with water, or, even with a far more penetrating and abstersive liquor. The like durableness I found in the Purple spots, that I sometimes purposely made on my Nails, by letting some little drops of the solution of Gold in Aqua Regia dry upon them, which I now and then did, to observe the way of the Nails growth. For if the stain were made near the root of the nail, it would be still, though very slowly, thrust on by the new matter, till after some weeks it arrived to the further end of the Nail, and was fit to be pared off with it. But this only upon the by. 'Tis more to our pur∣pose to take notice, that, though the Menstruums imployed in the recited
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Experiments be of themselves very acid and corrosive, yet they are so changed by the metals they have dis∣solved, that they are Acid no more, the solution of Silver being rather ex∣treamly bitter, and that of Gold of a kind of Stiptic tast, almost like that which sloes, growing in the hedges, are wont to be of.

Ivory is a thing too well known to need to be described. And, since 'tis generally lookt upon (for I have had no opportunity to compare it with the Bones) as the solidest part of the vastest of Terestrial Animals, Expe∣riments proving its porosity, will be strong presumptions for that of the hardest parts of other Animals. And the Porousness of Ivory may be argu∣ed from the several ways of dying it with permanent colours. For in these colorations the Tinctures that make them, must penetrate into, and be lodged in the Substance of the Ivory, especially when the Substance remains smooth and glassy, as I have divers times made it do, when I employed
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fit Menstruums and Metalline Pigments. The solution I formerly mentioned of Silver in Aqua fortis, being laid upon Ivory, will soon give it a dark and blackish stain, which is not, that I have found, to be washed off. I remember also that I many years since taught some ingenious artificers, to adorn Ivory with a fine purple colour, by moistening it with, and suffering lei∣surely to dry on it, a solution of Gold made in Aqua Regia. And if occasion required, allayed with water, nor needs either of these solutions be ap∣plyed hot, any more than the Ivory needs to be heated. Both which cir∣cumstances favour the Porousness of the solid Body.

Copper dissolved in Aqua fortis stains Ivory with a blewish colour, as I have sometimes seen in the hafts of knifes, about whose coloration never∣theless another way is also employed. But I remember that without making use of any Acid or Corrosive Men∣struum, I have even in the cold stained Ivory, with a fine and permanent
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blew, like a Turquois, by suffering to dry upon it as deep a solution as I could make of Crude Copper, in an urinous Spirit, as that of Sal Ar∣moniack.

But now to return to Bones, their growth in all their dimensions, does, as I lately noted, argue their Porosity and the marrow that is found in the great hollow Bones, whether it nou∣rish them or no, must it self be supply∣ed by some alimental juice, that soaks or otherways penetrates, into the ca∣vities that contain it.

Nor does it seem at all improbable, that Blood it self may through small Vessels be conveyed into the very sub∣stance of the Bone, so as that the Vessels reach at least a little way in it, though perhaps the Liquor they carry may afterwards by Imbibition be brought to the more internal parts of the Bone. For not to urge that we manifestly see, that on each side of the lower Jaw, Nature has been careful to perforate the Bones and make a Chan∣nel in the substance of it; which Chan∣nel
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receives not only a larger Nerve but a Vein, & Artery to bring in & carry back Blood for the nourishment of the Teeth, by distinct Sprigs sent from the great branch to the particular Teeth. Not to urge this, I say, (which I mention but to shew that the opi∣nion lately proposed is agreeable to a known practice of Nature) I have been assured by eminent Anatomists, whom I purposely consulted, that they have observed Blood-vessels to enter a great way into the substance of the larger Bones. And one of them affirmed, that he had traced a Vessel even to the great Cavity of the Bone. Which I the less scrupled to admit, because it has been observed, that in younger Animals the Cavity is in great part furnished with Blood▪ as well as Mar∣row, and in those larger Pores, where∣of many are found in the more Spongy Substance of divers Bones, Blood has been observed to have been lodged, as also in the spongy part of the Skull, that lies between the two Tables, as I have been assured by Skilful Eye∣witnesses.

Page 62
The blackness also, that Bones ac∣quire when put into a competent heat, and a peculiar kind of fat∣ness which they may by heat be made to afford, shew that they harbour, even in their internal parts, store of Unctuous Particles, separable from the solid substance, (which still retains its shape and continues solid) in whose Pores they may thereby be argued to have been lodged. The Lightness of Bones, even when their Cavity is accessible to (Air and) Water, is also a great sign of their Porosity. And so is their being cor∣roded by tinging liquors, if they be penetrative and well applyed. I know not whether I should add on this oc∣casion, that having taken calcined and pulverized Bones, such as we use to make our Cupels of, and, after having given them a good heat, kept them for some time in the Air, but in a well covered place; I found the imbibed moisture of the Air to have manifest∣ly increased their weight; and that I also observed in a curious Skeleton,
Page 63

where the Bones were kept together by wires, instead of other Ligaments, that though I kept it in a well cover∣ed place, not far from a Kitchin Fire, yet in very moist weather the Bones seemed to swell, since those joynts that were easy to be bent, in dry weather, and that after several man∣ners, would grow stiff and refractory, and indisposed to be put into such motions, when the weather was con∣siderably wet. These particulars (as I was saying) I am somewhat doubt∣ful whether I should here insert, be∣cause one may suspect the Phaeno∣mena may proceed rather from some∣what else, than the imbibed moisture of the Air; and yet I would not omitt to mention these observations, because I do not yet see any cause to which they may more probably (or indeed so probably) be assigned.

And on this occasion I shall subjoyn some observations made on large and solid Ox Bones, which in one of my Note Books I find thus registred. Nov. 15. We weighed two [entire or un∣broken]
Page 64

Marrow Bones, and found the one to weigh ℥xxix + ʒss, and the other ℥xxiv + ʒiv + 30 gr. Nov. 24. The former weighed ℥xxix + ʒvi, and the latter ℥xxv + ʒi + 30 gr. Decemb. 28. the former weigh∣ed ℥xxix + ʒiij. 55 gr. and the latter ℥xxiv + ʒvii. + 39 gr. June 7th of the following year, the former weigh'd ℥xxix + ʒii. And the latter ℥xxiv + ʒvii. By which observations purposely made at differing times of the year, and in very good scales, it seems that Bones do plentifully enough imbibe the Exhalations of the Air, and emit them again, together with some of their own, according as the ambi∣ent happens to be disposed. And these alterations argue the Bones to abound with Pores, since the external steams must have Pores to receive them, and the Effluvia must upon their recess leave Pores behind them.

I confess that to think (as with some Anatomists I lately seemed to do) that Bones themselves admit in∣to their substance, Vessels capable of
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conveying a nutritive Liquor, we must suppose those Vessels extreamly slender. But that 'tis not only possible but somewhat credible, there may be such, I am induced to think, by what is known to happen in that disease, which from the Country it most infests is called the Plica Polonica. For, tho one would think that the hairs of men are much too slender, to have cavities in them capable of visible Li∣quors; and though I have found it very difficult, even with a good Microscope, to perceive any cavities in the hair of a man transversly cut; yet not only some other writers of good note, but the Judicious Sennertus himself deliver, that in this disease (of which he par∣ticularly treats) it has been observed, that if the Patients cause their intan∣gled hair to be cut, as they sometimes do, by reason of its nastiness or un∣sightliness, they are not only thereby endangered, but sometimes the single hairs will actually bleed, where the ends have been cut off; so that so thick a Liquor as Blood may be conveyed
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through Vessels, that can at most be but in a proper sense Capillary and must be far less than hairs, if their Perfora∣tions be like those by which many Plants have their nourishment con∣veyed to them, or such as are obvious in divers Canes, which being cut quite through transversly, discover a mul∣titude of distinct Pores, that by some Experiments one may be induced to guess, reach all along, and make the Cane like a Cylindrical Bundle of Minute Pipes; or rather a multitude of small cavities, that perforate from end to end the Parenchyma, or Substance analogous to it, that gives them stabi∣lity. And for the present this sort of Vessels seem to me, the more likely to be those that convey the Blood to the extream Parts of the Hair, be∣cause even in Horse hairs, which yet are nourished and grow, I am not yet sure, that I have discovered with my Microscopes any cavity, and there∣fore suspect there may be divers im∣perceptible ones, for the Hair is nou∣rished and grows, which it is not like
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it should do if the Body were solid; and if there were but a single cavity in it, as in the lower part of a Quill, 'tis like the Microscope I used would have dis∣covered it, since with one much infe∣riour I could easily see, that several little short Hairs, that grow upon the Animal that yields Musk, had each of them a cavity in it like that of the lower part of a Quill.

To the things that have already been said about the Porosity of Bones, I shall now add an observation of a very learned Physician, that is very remarkable to our present purpose, because it argues, that even Bodies not saline, nor actually moist, may from without get into the Pores and Cavities of Humane Bones. Divers Physicians have complain'd of the mis∣chiefs done to the Bones by Mercu∣ry, employ'd to salivate in Venereal Diseases. Whereof I remember I have read a very notable Instance, in a learned Book (which I have not now by me) of an eminent Roman Pro∣fessor of Physick, who had the oppor∣tunity
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of making several curious ob∣servations in the famous Hospital of the Incurabili at Rome; and is there∣fore the more to be credited; where he relates, that in the Cavity of at least one Pocky-mans Bones, there was found real Quick-Silver that had pe∣netrated thither. And this brings into my mind a memorable observation of an ancient and experienced Physi∣cian, who being famous for the cure of Venereal Diseases, was asked by me, what Instances he had found of the Penetration of Quick-Silver, either outwardly or inwardly administred, into the Bones of men? To this he answered, that he could not say he had himself taken notice of any Quick-Silver, in the Cavities of greater Bones, but that some other Practition∣ers had told him, that they had met with such Instances, as I enquired after. But for himself, he only remem∣bred that a Patient, who had been ter∣ribly fluxed with mercurial Inunctions, coming afterwards to have one of the Grinders of his lower Jaw pulled out,
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because of the raging pain it had long put him to; my Relater had the cu∣riosity to view narrowly this great Tooth, and found, to his wonder, a little drop of true Mercury in that slender Cavity of the Root, that ad∣mits the small Vessels which convey nourishment and sense to the Tooth, in more than one of whose three Roots he affirmed to me that he found true, though but exceeding little, Quick-Silver. But a full Testimony to my present purpose is afford∣ed me by the experienced Physician Eustachius Ru∣dius, who relates,* that he saw himself, and that others also observed, some Bodies dissected, of those that had been a∣nointed for the Venereal Pox, in the Cavities of whose Bones no small quantity of Quick Silver was got to∣gether, (which yet (to add that upon the by) he says, did not hinder some of them from living many years, sur∣viving those Inunctions.)

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CHAP. VIII.
I Am not ignorant that, among the Particulars laid together in the foregoing Essay, there are some that are not absolutely necessary, to prove the Porousness of the Bodies of Animals. But I thought it not impertinent to mention them, because I hoped that they, in conjunction with the rest, may be of some use to Naturalists, in giving an account of several things that pass in a Humane Body, whether sound or sick, especially if it be of a Topical dis∣ease, and may remove, or much lessen that great Prejudice, that makes ma∣ny (and some of them otherwise learned) Physicians despise the use of all Amulets, Pericarpia, and other ex∣ternal Medicines in Distempers of the Inward parts, upon a confident, but not well grounded supposition, that these Remedies immediately touching but the outside of the Skin, can∣not exercise any considerable opera∣tions
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upon the internal parts of the Body.

But though I have thus acknow∣ledged some Passages of the foregoing Essay to be supernumerary, yet I must not dismiss it without intimating that I might from one Topick more have fetched a probable, though not a de∣monstrative argument, in favour of the Porousness of Animals. For this may be very probably argued from hence, that even Inanimate, Solid and Pon∣derous Bodies, that in all likelyhood must be of a far closer Texture than the living Bodies of Animals (whose various Functions require a greater number and diversity of Pores in their differing Organs) are not devoid of Pores, and have some of them very numerous ones, as will be sufficiently made out in the following Essay, to which I shall therefore hasten.

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N. B. The following Paper is that which is refer'd to in the 35th Page of this Essay.
*Hujus rei veritatem comprobat Doctissimus ac celeberrimus Medicus & Philosophus D. Johannes Chrysostomus Irmbler, Statuum Moraviae Marchionatûs Pro∣tomedicus, his verbis ad me scribens: Et revera paravi ego, Anno M. DCLV, quo tempore inter Infectos versabar quo∣tidie, Trochiscos Bufonios, eósque ut caetera Helmontii, indefessi veritatis indagandae, & ex puteo Opinionum ve∣terum nostram credulitatem excaecanti∣um eruendae, nati Philosophi, experi∣menta suas laudes sustinere comperi: Inter, viginti autem Bufones vix unum quidem, jucundo sane spectaculo, vidi ver∣miculos, per nares & oculos egressuros, manu repellere quamdiu poterat, doxec elanguerit Bufo: sed Trochiscos ex vermiculis unà cum pulvere emo•∣tui bufonis, & materiâ per anum (non∣dum
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vidi per vomitum;) scilicet alis, pedibus, capitibus, ventribus Scara∣baeorum viridibus, auratisve & ni∣gris, quos bufo cum terra in escam vena∣tur, ejectâ, cerea patinâ exceptis, cum Tragacantho rosato formatos, pluribus personis super anthraces opponi feci, at{que} nullum eorum mortuum esse dicere pos∣sum, sed & meorum domesticorum, ut & aliorum, quibus dedi, amicorum nullus, quod scio, infectus est. Sic comperi non tan∣tùm hisce Trochiscis enervari virus pestilens in Carbunculo jam admissum, ut dein vulgaribus chirurgicis remediis ulcus facili negotio fuerit curatum, sed etiam ad sinistram mammam liga∣tos, mihi meísque accursui & occur∣sui infectorum expositis, animositatem quandam indicibilem conferre, atque ita miasmata & effluvia pestilentialia abarcere. Hucusque Excel. Medicus Moraviae.


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An Essay of the POROUSNESS OF SOLID BODIES.
CHAP. I
AS 'twill with far less difficul∣ty be allowed, that Animals and Vegetables, and such Bodies, as have belonged to either, abound with Pores, than that Inanimate, Solid, and even Ponderous Bodies are not destitute of them: So 'tis far less difficult to make out the former than the latter of these Propo∣sitions.
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And therefore, Pyrophilus, I hope you will not expect that I should give you as many proofs of the one, as I have of the other; however I despair not, that those I shall present you, will appear sufficient for my pur∣pose, though they be not numerous enough to make me careful to mar∣shal them in any exact order.

Of the reasons that induce me to think that even Solid Bodies are not destitute of Pores, there are some that have a greater Affinity with those ar∣guments that the Schools are wont to call à priori, because they require more unobvious Ratiocinations upon Phy∣sical Principles, and others which re∣semble, and indeed are, such proofs as are usually named à posteriori, being suggested by the Phaenome∣na afforded us by experience, with∣out the help of any difficult Ratioci∣nations.

Of the First sort of Reasons I shall propose to you three; and begin with that, which may be drawn from the Origine and Formation of divers hard
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Bodies.* For I have else∣where endeavour•• and I hope not unsu•¦cessfully, to shew, both that divers stones, and even Gems themselves, and that several Metalline and other Mineral Bodies, were once either vi∣sible Liquors or at least very soft sub∣stances. And I have elsewhere proved, that both these kinds of Bodies do con∣sist of, (which is the case of Liquors) or abound in (which is the case of soft and moist Bodies) minute particles of determinate Sizes and Shapes; from whence I think one may very proba∣bly conclude, that such Gems and o∣ther Mineral Bodies, notwithstanding any hardness they afterwards come to acquire, are not destitute of Pores, since 'tis no way likely, that Corpus∣cles of various and very irregular Fi∣gures, such as those of most Liquors of the terrestrial Globe are wont to be, can be so brought together, especially by chance, cold, or any other such a∣gents, as not to intercept little Intervals or Pores between them.

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CHAP. II.
ANother thing which makes me think the Porosity of the most part even of Solid Bodies to be great, is the consideration of the great dis∣parity, that may be found in the spe∣cifick Gravities of such Bodies, as the Eye does not perceive to be Porous. For, though Water be a Body of that kind, and though its parts be so close packt together, that the attempts of In∣genious men, to make a manifest com∣pression of that Liquor by outward violence, have not hitherto proved successful, yet we find, that stones, Clays, metals, and even some Woods and a multitude of other kinds of So∣lids, will readily sink in Water, and by consequence are specifically heavyer than it; which greater gravity seems not any way explicable, without sup∣posing, or at least so well as by sup∣posing, that the Corpuscles whereof
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such sinking Bodies consist, do either lye closer together, or are separately more solid, than those of Water; which Liquor must consequently be Porous, though neither the Eye, nor the great force that has been several ways em∣ployed to compress it, can discover any Pores in it. Upon the same ground I further conclude, that solid Stones themselves, as Marble, Flints, &c. Are not free from Porosity. For whereas, as far as several Tryals purposely made can inform me, I have found, that such of these as have nothing metalline in them do seldom or never reach to treble the weight of an equal bulk of Water, they will, upon the former grounds, appear to be consi∣derably Porous; since the lightest me∣tals, which are Tin and Iron, are a∣bove twice heavier in specie, that is, the bulks being equal, than Marble, Flints, Chrystal, &c. And by the same reason I also infer the great Porosity, even of the Solid Body of Iron, which is as well heavier, as very much harder, than Tinn. For though
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Copper be a good deal more ponde∣rous than Iron, or Steel, yet I have divers times found fine Gold, to be more than twice as heavy in specie as Copper, since, whereas this Metal, whether it be European, or brought from Japan (for of that also I made Tryal) is about nine times as heavy as so much Water; I found refined Gold to be about nineteen times as heavy as Water equal to it in bulk. By which it seems highly probable, that so solid and heavy a Body, as Iron or Steel it self, may be so porous, that Me∣talline matter equal to it in weight may naturally be contained in much less than half the Dimensions that Metal possesses. And that Gold it self, which is the most comPact and solid Body we know of, is not destitute of Pores, may appear by the Dissolution of it in Quick-Silver, of which I shall speak a little below. And if any should pre∣tend, that hardness may be a greater argument of the Compactness of a Body, and its immunity from Pores, than its specifick weight can be; I
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shall add, that though I have found that Emery, which is the Body em∣ployed to cut steel and Load-stones and Crystal, and the most of Gems, being indeed much harder than Mar∣ble or Flints, be far heavier than thrice its bulk of Water; yet that ponde∣rousness proceeds, as I else where inti∣mate, from the mixture of a metal∣line Substance, which I have separat∣ted from it. And Diamonds, though much harder Bodies than Emery, and indeed the hardest we know of in na∣ture, are so far from being, as some of late have written, the most ponde∣rous of Bodies, that having examin∣ed them hydrostatically, by a way elsewhere mentioned, I found them not much heavier than either Crystal, or fine Glass, and not half so heavy as the lightest Metals.

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CHAP. III.
THe next thing, from which the Porousness of Solid Bodies, and even those that belong to the Mine∣ral Kingdom (as the Chymists speak) may be deduced, is the same with the first of those from which we former∣ly argued the Porosity of Substances belonging to the Animal Kingdom, namely, the very frame & constitution of such Bodies. For the solidest Bo∣dies themselves, resulting from the Convention or Coalition of a great number of Particles of several big∣nesses and shapes, we cannot reason∣ably suppose, (especially in those concretes wherein they are not ran∣ged by a seminal Principle) that they should be contexed so, as to touch one another exactly every where and therefore they must of necessity leave some little Intervals and Pores be∣tween them.

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This reason will, I hope, appear clear enough of it self, to him that shall attentively consider it, especially if he know, that it has been Geome∣trically demonstrated, that there are but very few figures that will, (as they speak) implere spatium, that is, which being adjusted to one another will so exactly touch, that there is not the least unfilled space within the cir∣cumference or circuit, if the figures be plain, or within the ambient Super∣ficies, if they be solid; so that, consider∣ing the vast variety of other Figures, which made Epicurus and other Ato∣mists pronounce it incomprehensible, 'tis very obvious to conceive, that Cor∣puscles of such differing shapes being put together, will leave multitudes of little Pores intercepted, between those parts that do not every where touch one another. And even the Mathema∣tical Figures lately spoken of, may be said to fill space rather in a Geome∣trical than a Physical sense. For, if such Portions of matter as are requi∣red to constitute, for instance, a Cube,
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were actually put together, they would not exactly fill the space com∣prehended within the ambient sur∣face of the Body they compose, because the component Bodies, being Physical, consist of Corpuscles of their own par∣ticular shapes, which we never find Mathematically exquisite. As if, for example, the Cube were of Marble, no Art could polish the sides of a com∣ponent Body so, as that they should be perfectly smoothed since (as, if I mistake not, the learned Gassendus well observes) Emery, Pumice-stone, and even Puttee, or other Powders that are employed to polish them, do them∣selves consist of little hard angular Corpuscles, that leave small scratches, like so many little furrows, on their surfaces, which must needs hinder the perfect contact of the whole surfaces of two contiguous Bodies, and conse∣quently leave here and there Intervals or Pores, between those surfaces; to which I shall add that Marble it self as 'tis Marble, abounds with internal Pores, as will ere long appear by
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Experience, and as may be rationally conjectured from the Specifick Levity of it, in comparison of Gold and Lead.

CHAP. IV.
HAving dispatched the Argu∣ments à priori, that may be imployed to shew the Porousness of Solid Bodies, 'twill be now season∣able to propose some Experiments and observations, that may (as 'twere) à posteriori either evince or confirm the same Doctrine.

Of these Instances some relate to Solid Bodies that are of less specifick gravity some to Fossiles presumed to be devoid of Metalline parts, some to Minerals that are thought to par∣ticipate of a Metalline nature, some to Metals themselves, and some to Glass.

To begin with the first sort of these Instances; That Wood is Porous, there are many things that argue; some of which are elsewhere mentioned. But few would suspect, that Quick-Silver which is so unapt to enter the Pores
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of Bodies much less compact, should permeate peices of Wood of a conside∣rable thickness; and yet, that we have made it do by the following Experi∣ment. We took a wooden Trunk, such as is employed to shoot pellets at Birds, with strength enough to kill them, and having closely stopt one end of it, we poured in Quick Silver at the other, till it reached to a good height in the cylindrical Cavity of the Instrument, and then the lower parts of the Me∣talline Liquor, being assisted by the weight of the Incumbent ones, (not to mention that of the Air) to press into the Pores of the Wood, they issued out at them on all sides, in great num∣bers of minute drops, much after the manner of Quick-Silver strained through Leather, out of amalgams; which was a Phaenomenon not unplea∣sant to behold. But till I have oppor∣tunity to repeat this Experiment with differing circumstances, I shall not think it fit to lay much stress upon it, for want of knowing, what interest the great weight of the Quick Silver may have had in the event.

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And this caution may perchance be applicable to the following Expe∣riment, namely, that having, by the help of my Pneumatical Engine, with∣drawn the Air from one side of a round peice of board, the Air on the oppo∣site side, not having its pressure any longer resisted by that which it used to meet with from the withdrawn Air, pressed so strongly against the sur∣face of the Wood exposed to it, as to make it self way through the Pores of it, and get copiously enough into the Cavity whence the other Air had been pumpt out; (the weight of the incumbent Atmosphere doing on this occasion, what the weight of the Quick-Silver did on that last recited:) Which was a surprizing spectacle to the by-standers because the board that was thus permeated, was of strong Wood, and of considerable thickness.

I should here subjoin several other Ar∣guments of the Porousness of Wood, if I could display them without more words, than I am willing to allow them;
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and I presume it may here suffice, if I let you see by some surprizing Effects that when Wood is reduced to that thinness, that its closeness or Porosity may conveniently be examined, it will easily enough give passage, even unto visible, odorable, and tinging Corpuscles though they invade it not in the form of a Liquor, but of dry Ex∣halations, so they be not incommensu∣rate to its Pores. This I suppose, you will not scruple to infer from the fol∣lowing Tryals, as they were long since set down in one of my Note-Books.

1. The Fumes of our smoaking Liquor [described in the foregoing Essay] tinged a Copper half penny, through a broad thin shaving of Dale, that did not, when held against the window, discover any perforation; tinged it, I say, very deeply in about a quarter of a minute and somewhat less.

2. The same Fumes tinged mani∣festly, but not so notably, the same half penny first cleansed through two such shavings of Dale, laid one upon
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another in somwhat less than one minute.

3. And in about one minute the same Fumes tinged the cleansed half penny, through three such shavings of Dale very visibly, but not so conspi∣cuously, as through the two foremen∣tioned. These Tryals were made with∣out the help of heat to promote the o∣peration of the Fumes.

CHAP. V.
FRom the consideration of Woods let us now proceed to give some Instances of the Porousness of Bo∣dies made of close and compact∣ed, and perhaps well baked Clays or other Earths.

That Earthen Vessels, thô strong and well bak'd, are many of them porous enough may be argued not only from what has been lately reci∣ted, but from hence, that some of them will suffer themselves to be
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soakt through by Oyl. Others by so∣lutions of Nitre, and some other Salts. And there are very few of them, with∣out excepting Hassian Crucibles them∣selves, that will long keep Salt of Tar∣tar, and such like fixt Alcalies, in fusion without being penetrated by them. I have heard Distillers complain, that when they have distilled corrosive ma∣terials, as Vitriol and Salt-Petre, with strong fires, in those Earthen Vessels that are commonly made use of in London (especially by refiners) in∣stead of Retorts though their necks be strait and long (upon which ac∣count they are called long-necks) a considerable quantity of the finest Spirits make their escape quite tho∣row the Vessel; so that in the Retort and Receiver many ounces are found want∣ing, of the first weight of the matter to be distilled. And this sometimes, when the Vitriol has been previously calcin'd, and a reasonable allowance has been made, for what may have escaped thorow the Lute, that joined together the long Neck and Receiver.
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And though I have observed of our Bottles, made of the same Earth with Juggs, that they are hard enough to strike Fire with a good Steel, yet a good Experimenter upon such Vessels of whom I made enquiry, has assured me that these, as compact as they are, may, even without external heat, have their Pores pervaded by the finer parts of Spirituous Liquors.

To this purpose I remember that meeting once with a Virtuoso, that was curious about the ways of making Si∣der as brisk and spirituous a Liquor as he could; I enquired of him, whe∣ther he was able to keep in the subtil Spirit of this Skilfully fermented Li∣quor, in those earthen Bottles, that, by reason of the solidity they acquire by the vehement coction of the Fire, are commonly called stone Bottles; to which he replyed. that he often found to his trouble, that the Liquor would permeate the compact Substance of the Bottles: And when I objected that the Spirits might either escape out at the Cork, which I have made several Spi∣rits
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of divers kinds that would readily permeate; he replyed, that what he had said appeared by the outside of the Bottles: To which when I further ob∣jected, that the sight of dew on the sur∣face of the Bottles, would not convince me, without tasting whether it were vinous, because I had divers times observed, that brisk Liquors would produce a dew, on the outside of the Vessels that contained them, not by any transudation (for I have made Tryal of it in Glasses) but by conden∣sing the aqueous vapors, dispersed through the neighbouring part of the Ambient Air: He replyed that, besides what his tast had informed him of the quality of this dew, he found that the included Liquor, though exactly stopt, wasted in not very many Months so considerably, as sometimes to lose a sixth, or even a fifth part; & this escape or percolation of the Liquor through the Substance of the Vessels, he affirm∣ed himself to have observed, not only in one or two Bottles, but in very many and the like observation for the
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main was confirmed to me, upon his own experience, by an eminent Physi∣cian, who, being a great Lover of brisk Sider, used to bottle it up early and carefully.

Though good Hassian Crucibles be very closely compacted, as well as throughly baked Bodies, and upon that account are able to keep Silver and divers other Metals long in fusion, without letting them at all run out; yet having dissolved Silver in Aqua fortis, I observed that, though the Salts were by this operation so chang'd that this horn-like Silver did dissolve nei∣ther in the Aqua fortis, nor in the Aqua Regia that I put it into; yet when I kept it a while in fusion, (which 'tis easily brought to be) among quick Coals, it would without cracking or perforating the Crucible, soak into it, and permeate the Pores of it, in I know not how many places, as I convinced some curious persons, by shewing them on the outside of the Vessel, a multitude of minute globules of pure Silver, like so many little drops, that
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were got thither, as it were, by transu∣dation.

CHAP. VI.
FRom baked Earths, that are de∣signed in point of hardness to emulate stones, we will proceed to give some instances of the Po∣rousness of Natural Stones them∣selves.

There goes a tradition, that in some part of the West-Indies they have a Stone, of which they make large Ves∣sels, wherein they put Water to perco∣late, as it were, through a strainer. Of these Vessels I had one sent me for a present, whereof being hereafter to give some account in a more op∣portune place, I shall now only take notice that I found that Water would (thô slowly) soak through the Vessel, thô it were considerably thick.

If, as many of the Ancients, and
Page 95

most of the modern Corpuscular Phi∣losophers have conceived, the Transpa∣rency and Opacity of Bodies proceeds from a Rectitude or Crookedness of Pores, which makes them fit or unfit to transmit the Light, that tends to pervade them in Physically straight Lines: If this Hypothesis, I say, be al∣lowed, we may draw a very proba∣ble argument, that Stones may be Porous, from the Phaenomena of that odd Gem, that is best known by the name of Oculus Mundi. For this small stone (at least that which I made my Observations of) when 'tis dry, and is kept in the Air, is opacous, almost like a polished piece of white Am∣ber, and so it continues, as long as 'tis kept dry. But if you put it into fair water, it will in no long time, be∣come by degrees quite Transparent, and that which I made Tryal of look∣ed then not unlike a piece of clear yel∣low Amber which by degrees does in the free Air lose its Transparency and turn to be opacous as before. Now according to the above mentioned
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Corpuscular Hypothesis, the Pellucidness which the Stone acquires in Water, may be accounted for, by saying, that the Liquor getting in at the crook∣ed Pores of the Stone, does for the time rectify them, and make them per∣vious to the straight Beams of Light; as we see that White Paper, being wetted with Water, or, which does far better, being made so imbide Oyl, has its Pores so changed and rectified, that the Water much lessens its Opacity, and makes it almost Semidiaphanous and the Oyl, if it be fine and well soaked up, makes it Transparent. But upon the recess or evaporation of the imbibed Particles of Water, the Pores of the little Stone becoming crooked again reflect the Rays of light they should transmit. Which explication will be the better allowed of, if my memory do not misinform me, when it tells me, that a learned Mem∣ber of the Royal Society found the Oculus Mundi to weigh more in a nice ballance, when it was taken out of the Water and well wiped, than be∣fore
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it was put in. This Stone, which very few of the writers about Gems take notice of, is so rare and difficult to be got, that I had not opportunity to make upon it all the Tryals I de∣sired; and therefore, though the Sub∣ject be curious, I may, I hope, be ex∣cused, if I hasten from it to ano∣ther.

There is so much difference in ma∣ny Qualities betwixt Stones and Me∣tals, that 'tis very probable, that when the Corpuscles of both come to be brought together into one Mass, they will not touch one another so close, as not to leave store of little Intervals or Pores between them. And upon this ground I have been apt to think that divers very hard Stones, Diapha∣nous and Opacous, are not devoid of Porosity. For I have elsewhere deli∣vered a way by which I have obtain∣ed good store of Metalline parts, both from American Granats, and from Emery; though this last be so exceeding hard a Stone, that 'tis usually im∣ployed by artificers to work upon
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Iron and Steel, and to cut not only Rock Crystal, but divers Gems that are harder than either that or Steel.

Upon the same ground one may probably infer the Porosity of many Artificial Gems made by Fusion; for to give these the colour of Sapphirs, To∣pazes, Amethysts, &c. we are wont to add to the vitrifiable matter, either some prepared metal, as calcined Cop∣per, calx of Gold, &c. or else some Mineral as Zaffora and Manganeze (as the Glass-men call Magnesia) that a∣bounds in Metalline parts. Nay I re∣member, I have sometimes given the colour to the vitrified substance, by imploying natural Gems, as Granats; though to shew that the coloration which the mass received from these, proceeded from the Metalline Corpus∣cles, that lay hid in the tinging matter, the Colour produced was not that which was conspicuous in the Gem it self, but one very different from it, and such as the metal, which upon other accounts I supposed the Gem to partake of, ought, according to the
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Grounds I proceeded upon, to pro∣duce in the vitrifiable matter. And this very Experiment makes it also highly probable, that even natural transparent Gems, (divers of which are much harder than Marble, Iron & even Steel) are themselves Porous; since, notwithstanding their Transpa∣rency and seeming Homogeneity. They are made up of Ingredients of such differing natures as are Stony and Metalline Corpuscles.

From the same Ground we may likewise deduce the Porosity of Mar∣casites; many of which I have obser∣ved to be, not only hard enough, plen∣tifully to strike fire by collision with Steel, but more ponderous than even divers Oars, that were rich enough in Metal, to be wrought with good profit. And yet these hard and heavy (Mineral) Stones are very far from being homogeneous; since I have met with few Inanimate Bodies, produced by Nature her self, so com∣pounded as several Marcasites that I have seen. For these are wont to con∣tain
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more or less Copper, and Iron too: and they abound in Combustible Sul∣phur, a Corrosive Salt, and a certain Fixt Substance, which I found to differ from true Earth, but of whose Nature the Tryals I have hitherto made on it, have but little satisfied me.

I might here deduce the Porosity of the Load-stone, as hard and solid a Body as it is, partly from the Effluvia it emits and admits, and partly from the Heterogeneity I have by Chymi∣cal Tryals found to be in it. But these things belong more properly to a Pa∣per about Magnetical Bodies, for which I the more willingly reserve them, because other Experiments will keep them from being needful to be here insisted on.

The Porosity of Marble, and divers other Stones of like Contexture, may with probability be deduc'd from this, that they are liable to be dissolved by divers of the corrosive Menstruums of the Chymists, such as Aqua fortis sp. of Salt, &c. And some of them even by Vegetable Liquors, of Natures own
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preparing, as the juice of Limons, and that of Barberries. But a more noble and satisfactory instance may be afforded, by the invention of staining or colouring white Marble, without imploying any fretting Liquor, or spoiling the Texture of it. This way being casually lighted on by an ingeni∣ous Stone-cutter in Oxford, who gained by it both credit and money, he long since thought fit to acquaint me with it, upon condition of secresy (which I have to this day inviolably kept) and of my assisting him to improve his Invention by making it practicable with other Colours than Red. These circumstances I mention, to signify that I write not by guess, of this mat∣ter, having both seen the Experiment tried, and made it my self. But though I found it far less improvable to other uses, then one would expect, yet, as to our present purpose, it is very ap∣posite. For by this way an excellent red Colour, may be made to soak into a piece of White Marble, almost as Oyl will do into Leather, without
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impairing, that I observed, the soli∣dity of the stone, which, after being dyed, will be capable of a fine gloss as before. Some other Colours (yet but few fair ones) would by this way be brought to soak into Marble, on which one may with them so define, and limit the Colorations, that I re∣member the Artificer, when I brought him to kiss the Kings hand, presented His Majesty with an Andromeda, whose Colours were so vivid, that this skilful Judge of curious things, was pleased to honour it with a place among his Rarities. And, to satisfy his Majesty that the fine Red was not, as some suspected, a mere varnish, I purposely broke a plate of Marble, in whose fragments he saw, that the Pigment had sunk to a considerable depth, into the very Substance of the Stone. And I doubt not but it might have been made easily enough to sink much deeper, if it had been thought necessary. A fine Plate of such White Marble, with the penetrating Pictures of Coloured Flowers drawn upon it I
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yet keep by me to satisfy the curious. And some Utensils, as Hafts of Knives, Salt-Sellers, &c. I have known to have lasted several years.

There is an Experiment that seems much stronger for the Porousness of Solid Bodies, than that it self (which was lately recited) of staining Marble. For in Italy some Goldsmiths have a way of imbuing Fragments of Rock-Crystal, which is a Body much harder than Marble, with divers Colours; which do sometimes so imbellish them, that having ground off those parts that would not receive the same Tincture, they set some of them in Gold Rings, and sell them with profit. When I was inform'd of this, I thought of a Composition, that I hop'd might perform the same thing, and perhaps better than that which was employ'd by them, who either knew not, or for ought I could perceive, us'd not, some Minerals that I thought fit for the purpose. Upon this Presumption we carefully cemented some clear Fragments of Native Crystal with a
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Composition of some Volatile Mine∣rals, together with a Salt or two, and having suffered the Crucibles to cool leisurely, we had divers of the Fragments stain'd here and there, some with one Colour and some with another, as differing Fumes happen'd to invade them. And of these Colours some were dark or dull, and some vivid enough. But having consider'd the stain'd pieces, and the progress of the Operation, more attentively, I began to doubt, whether these Adventitious Colours were really pro∣duced by the bare penetrating of the Mineral Fumes into the Pores of the Crystal it self. For I thought it possible, and not very unprobable, that the great Heat of the Fire, and the Am∣bient Mixture, might cleave or flaw in many places some of the Crystalline Fragments; and that the finer parts of the Minerals being vehemently agitated, might insinuate themselves into these thin Flaws, which upon the slow refrigeration of the Stones, shutting themselves close again, might
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lock up the tinging Particles, without appearing discontinued, especially to the Eyes of Persons that were not made use of with a more than ordinary at∣tention, excited by distrust. This suspicion was not removed by the apparent entireness of each little piece of Crystal. For having taken more than once a Lump of that stone, and slowly brought it to be red hot in the Fire, I found that if I warily quenched it in Water, though it would thereby acquire a multitude of little cracks or Flaws, which destroyed its former transparency, and made it look whi∣tish, yet it continued still an entire Body, notwithstanding the disadvanta∣geous haste, wherewith the operation had been performed. And having after this suspicion, inquired of an ingeni∣ous Lapidary, that belonged to a great Prince whether in polishing of Gems upon the Wheel, he had taken notice that the Heat would flaw them, he an∣swered me, that now and then he had observed that some Stones, especially▪ if I misremember not, Rubies, when
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they were very much heated by the swift motion of the Engine he employ∣ed to polish them, did cleave as it seemed to him, and gape, so as at first to make him fear the Stones were spoiled; and yet afterwards they closed so perfectly, that no Flaw at all could be perceived in them. I have mentioned the foregoing Experiment of tinging Crystal, to comply with the dictates of Philosophical candor, which forbids me to lay much stress upon a Proof, whose validity I my self distrust. But perhaps my suspicion may by further Tryal, which I have not now conveniency to make, appear not to have been well grounded, and in that case the tinging of Crystal, as well inwardly as outwardly, by Fumes will be a noble Argument for the Po∣rosity of Solid Bodies, Rock-Crystal being harder, and probably closer, not only than Marble, but even than Glass.

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CHAP. VII.
THat Metals, though the heaviest of Bodies, are not destitute of Pores, may be with probability proved in a general way by this; That they are all dissoluble in their appropriate Menstruums, as Gold in Aqua Regia, and all the rest in Aqua Fortis, except Tin, which yet it self will be corroded by that Menstruum, though not well kept up in a fluid form, as it may be by another Menstruum, which I else∣where teach; and sometimes the same Metal may be dissolved by very diffe∣ring Menstruums, as Lead by Aqua for∣tis, and Spirit of Vinegar; and Copper by Aqua fortis, Aqua Regia, Spirit of Vinegar, Spirit of Salt, and some other Solvents, that upon Trial I have found sufficient for that purpose.

But 'twill, I presume, be thought more considerable to my present ar∣gument, if it be shewn, that Bodies that appear Gross, and which in their Natural state are not fluid, and are
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confessed to be of a compounded na∣ture, will penetrate Metals quite through, even without melting them.

This we have divers times effected by a Cementation of Copper Plates, With common {sulphur} (much a kin to a way prescribed by some Alchymists to make Vitriolum Veneris) which we warily performed much after this manner. We took good Copper lami∣nated to the thickness of a Shilling or thereabouts, and having cut it into small pieces, that they might the more easily be put into a Crucible or Cemen∣ting Pot, we strewed at the bottom of the Vessel some beaten {sulphur}, and then co∣vered it pretty well with some of these Plates, which were laid on flat-wise. Upon these we strewed another Bed of powdered Brimstone, and cover'd that also with Plates, upon which we put more Sulphur, & so continu'd ma∣king one lair of Brimstone, & another of Metal, till we had employed all our Plates, or filled the Crucible, be∣ing careful that the uppermost Bed, as well as the lowest, should be of Sul∣phur.
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This done, we luted on an earthen Cover to the Vessel, to keep the {sulphur} from taking Fire, and afterwards having placed the Pot amongst Coals kindled at a good distance from it, that it might be heated by degrees, we kept it for some few hours (perhaps Two or Three) in such a degree of Fire as was sufficient to keep the Sulphur melted (which is easily enough done) without bring∣ing the Metal to fusion; the Pot be∣ing cold, we took off the cover, and found the Plates quite altered in Co∣lour and Texture, some of them hav∣ing a dark and dirty Colour, whilst others looked of a fine Violet or Blew; they were generally so brittle, that 'twas very easy to break them with ones finger, and reduce them to Pow∣der. And (now to add such Circum∣stances as a Chymist would not take notice of) many of the Plates, when they were broken, appeared to have been (by the contiguous Beds of Sulphur above and below) horizon∣tally divided each of them into two
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Plates, divers of which in some places had a manifest distance or Cavity between them. And 'twas observable, that when I considered one or other of these Plates attentively in the parts that had been contiguous before I broke it, I could plainly discern a mul∣titude as 'twere of Fibres, reaching from one of the flat sides of the Plate to the other, & running many of them, as to sense, parallel to one another. These Circumstances may sufficiently argue, that the Plates were pierced quite through by the Brimstone; but for confirmation of this, and to shew too that the Sulphur does as it were soak into the Body of the Metal, and in a Gross manner lodge it self there; I shall add, that not only to the Eye the Plates appeared much swelled, or thicker then when they were put in, but having weighed them before the operation was begun, and after it was quite ended, the Copper, though it needed not to be freed from externally adhering Sulphur, was found to have a considerable increase of weight by
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the accession of the Sulphur, which (to add that circumstance) though it appeared not to the Eye, yet if a Plate were laid upon quick Coles, and blown, would often∣times discover it self by a Blew flame.

By making the like Experiment for the main, we found that refined Silver, though a more heavy and compact Body, than Copper, and not dissoluble by most of the Menstruums, that work on this Metal, is penetrable by the Body of Sulphur, which will also cal∣cine Tin and Lead and (especially) Iron.

Nor is Sulphur the only consistent Body that has this ingress into Metals; for we have found them penetrable by prepared Arsenick. But because these operations are not so easy, and the Subject is not easily handled without danger, I forbear the mention of them in this place, where, after what has been recited, it is not ne∣cessary.

Another Experiment there is,
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which does more advantageously than that made with Brimstone, disco∣ver the Porosity of Copper. For there is a way by which, without the help of Salts, Sulphur or Arsenick, one may make a solid and heavy Body soak in∣to the Pores of that Metal, and give it a durable Colour. I shall not mention the way, because of the bad use that may be made of it. But having had the curiosity more than once to try it upon a new Copper Farthing, the event was, that one part of it, which I purposely forbore to tinge, remained common Copper still, but the other part acquired a yellow, that differed very little, if at all, from a Golden Colour, the former stamp that was impressed upon the coin continuing visible. And to convince the scrupulous, that the Pigment did really sink, and as it were soak into the Body of the Metal, and did not meerly colour the Superficies, I made them take notice, that the Farthing was not melted, and yet by filing off a wide gap from the Edge of the Coin, inwards, it plainly
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appeared, that the Yellow or Golden Colour had penetrated a pretty way beneath the surface of the Farthing; so that it looked there as if two thin Plates, the one Yellow, and the other Reddish, did, without any Interval be∣tween them, lye upon one ano∣ther.

If Bodies be not to be pervaded, or deeply pierced into, by Corpuscles, but only to have their more superficial Pores, if I may so call them, penetra∣ted thereby, 'tis possible that Bodies, which are either much harder, or much closer, than Marble, Alabaster or the like Bodies, may have their Pores possessed even by odorous Cor∣puscles; I say, even by such, because they are most of them gross enough to be kept from exhaling, by Bodies much less compact then Earthen Bottles; and are far from being of the finest particles that Nature affords. But that such odorous Corpuscles may lodge themselves in the exterior Pores of very close Bodies, I have been inclined to think, not only, by the obstinately
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adhering Odour, which I found by Tryal, that some suttle and Spirituous parts, such as the Chymists would perhaps call in their Aggregates, the Essence of Musk, Amber, Amber-greece, &c. notwithstanding the wash∣ing of the Glasses, that had long con∣tained such Liquors; but by what has been assured me by a Physician of great Experience, who travelled and lived much in the East. For having told him, that I had been informed, that in some places less famous then Damascus, for curiosity in making fine Sword blades, there was a way found and practised of making them richly scented, without injury to their Gloss; I desired to know of him, if at Damascus, or elsewhere, he had seen any of them; to which he replied, that he did not remember he had, but yet made no doubt the Information might be true. For he himself had in Europe, and kept for divers years, a Watch, whose Metalline Case, was richly perfumed; and when I askt him, whether there were not some
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thin varnish, or some outward Case of perfumed Leather, or Chagran, or somewhat else, from whence the odour proceeded, he assured me, that his observations had prevented and re∣moved that and divers other Scruples, and that the case being clean and Glossy, he could not per∣ceive that the Odour proceeded from any thing else, than some odori∣ferous thing, or other that was invisi∣bly lodged in the Pores, or Porous Substance of the metal it self. And indeed, since both Arsenick, and even common Sulphur, may by Art be as it were incorporated with some Me∣talls, and even with Silver, I see not why it should be impossible, that some pleasingly scented Substances should be admitted into the Pores of Metalline Bodies, and be volatile enough to have their subtiler parts fly off in odorous Exhalations, especially if they be a little excited, as the Watch Case lately mentioned was, by a gentle heat, such as was that of the
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wearers pocket. And on this occasion I remember to have made a certain Metalline composition, which looked like Gold, and of which I caused a Ring to be cast, and yet this Metal retained so many unperceived Mercu∣rial Corpuscles in it, that an Ingenious Person to whom I discovered the composition of it, found after Tryal, as he assured me, that being worn as a Ring, it had in some distempers, particularly of the Eyes, manifest ope∣rations, that evidently enough seemed to flow, at least in great part, from its participation of the Mercury we employed in preparing the Factitious Metal.

Since the writing of the former part of this Essay, having met with an inquisitive Nobleman, who had lived in several parts of Africk, and was Governour of the best Town the Eu∣ropeans have on that Continent, I dis∣coursed with him, among other things, about the Skill that some ascribe to the African Moors, of making excel∣lent weapons, whereof I knew his ex∣cellency
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was very curious. Upon which occasion he told me, that some of the Off-Spring of the Granadine Moors were indeed the best at making Arms that ever he met with; and that he had seen some weapons of their forging and tempering, that he preferred even to those of Damasco. And when I asked him whether any of them had the art of perfuming their Weapons, he answered me, that some of them did it admirably well, and instanced in a Blade which he kept for some years, & found it still to retain the perfumed scent, which he supposed to be as it were incorporated with the Steel whereof the Blade was made. When I told him, I suspected that the scab∣bard might have been well perfumed, and communicate its odour to the contained Blade, he allowed the ob∣jection to be plausible, but replyed▪ that it was not concluding, since mis∣liking the Scabbard, as not handsom & fashionable enough, he caused a new one to be made, wherein he afterwards kept it. And the same Lord further
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told me, that he had also a Fowling Piece, whose Barrel was perfumed. And when I objected that perhaps the odoriferous scent proceeded from the stock, and not from the Metal, he an∣swered that the Gun not being, when it came into his possession, skilfully and handsomely mounted, he caused the Barrel to be fitted with a new stock, notwithstanding which, it con∣tinued to smell fragrantly. And when I further asked, whether he ever caused the Gun to be washed or scoured after it was grown foul by having been of∣ten shot in, he answered me, that he had, and, as far as I can remember, sub∣joyned, that after it was made clean it did (notwithstanding the ill scent that the soot of the Powder had given it) retain a pleasing smell, but fainter than before.

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CHAP. VIII.
SInce the Subject of this Essay is the Porousness of Solid Bodies, and since there is no Body that is ge∣nerally reputed so close and compact as Glass, it will be pertinent to this discourse, and probably will be ex∣pected, that I should here say something about the Question, whe∣ther Glass be, or be not, devoid of Pores.

But before I acquaint you with my Tryals, or my thoughts, about this Problem, I think it requisite to clear the sense, in which I mean to handle it, that I may not, as some others have done, for want of distinctly stating the Question, speak confusedly and erro∣neously of it.

I shall then here observe, to prevent mistakes, that the Porosity of Glass may admit of two Acceptions. For it may be said to be quite pervious to
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Fluids, as a Boot is to Water, or only to be capable of having its superficial parts further and further dissolved or corroded thereby, as a Silver Cup is Porous in reference to Aqua fortis, which cannot sweat through it, as Water does through a Boot, but eat its way through it, by dissolving the Texture of the Vessel.

Another thing requisite to be pre∣mised, to prevent Ambiguity, is, that Glass it self is not all of one sort, as men unacquainted with Chymistry are wont to presume, for Glass of An∣timony, for instance, and that of Lead, both of them made per se, do mani∣festly differ, usually in colour, and constantly in weight, and also in their operations upon Humane Bodies; and both these sorts of Glass do in several points differ from common Glass, under which name, for brevities sake, I comprehend both White or Crystalline Glass, as 'tis called in the Shops, and that courser sort, which they usually call Green Glass; both which sorts I here consider under one Notion, be∣cause
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both are made of fixt Alcalies, and other fit Ingredients, as Sand, Earth, Ashes, Pebbles, or Flints, Colliquated by a strong & lasting ope∣ration of the Fire: and 'tis of this com∣mon Glass, in the sense now declared, that I shall consider the Porosity in the remaining part of this Essay. In which to proceed with some Method, I shall digest what I have to say into the ensuing Propositions, and the obser∣vations annext to them.

Prop 1. 'Tis very probable, that Glass may be pierced into to some distance, even by visible and tangible Bodies.
I know that this will seem a Para∣dox to many, and repugnant to common Experience, which shews that Glass Vessels will contain very subtile and even highly corrosive Liquors, as the Spirit of Hartshorn, of Urine, and that of Nitre; as also those potent Menstruums, as Aqua fortis, Aqua Regis, and Oil of Vitriol,
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which not only are not observed to pierce into it, but are unable to make any sensible alteration, so much as on the superficial parts, even in those Vials wherein they have been long kept.

But, notwithstanding all this, I presume you will not condemn the lately proposed Paradox, when you have considered what may be said to justifie it. For, besides that it may be made probable à Priori, by the Arguments whence we have formerly proved the Porousness of Solid Bodies in general; there are two sorts of Experiments, from whence one may argue, that Glass in particular is not devoid of Pores in the sense wherein we are now speak∣ing of them.

And first, I remember, that, having kept for a good while in a vial, a quantity of a certain Spirit of Salt, that I had reserved in a cool place; I found, when I came to use it, that the Glass was crackt, and most of the Liquor was run out; but, before this
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happened, it had so far corroded the inside of the Glass, that in some places it was eaten almost as thin as a piece of Paper; and this part which yet continued Glass, was lin'd with a much thicker white substance, that stuck to the sides of it, and look∣ed and tasted like a kind of odd Salt; so that it invited me to conjecture, that it proceeded from the substance of the Glass, which you know consists of an Alcali as well as of Sand cor∣roded by the Saline Spirits of the Menstruum, and coagulated with them into this odd kind of Concrete; and 'twas remarkable in our vessel, that the upper part of the vial, to which the Menstruum did not reach, was not corroded, nor alter'd, tho the operation of the Liquor reached as high as the Liquor it self. And I remember, that when I related all this to some experienced Chymists, one of them that was a more heedful observer, assured me, the like had once or twice, happened to him, as since that time it hath likewise done to me.

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I had also, if I misremember not, another Vial, corroded by a distilled Liquor of Vitriol, that had in it more of the Phlegm than of the Oil; which you will somewhat the less wonder at, if you consider, that some Corrosive Menstruums will scarce work on some Bodys, if they be too well dephlegmed, or at least will not corrode them so readily and powerfully, if they are very strong, as when they are diluted with a convenient quantity of Water. And, as to Oil of Vitriol it self, which is the Menstruum I am speaking of, when we employ it to make Vitriolum Martis, we are wont to weaken it with Water, that it may the better dissolve that Metal. And perhaps you will suspect, that Vitriol has some pe∣culiar faculty of penetrating and fret∣ting Glass, when to the Experiment newly recited I shall add that which follows, as I find it registred among my Notes.

[A pound of Dantzick Vitriol and a pound of Sea Salt, after the former had been very lightly calcined, and the
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latter decrepitated, that they might not boil in, or crack the Vessel; we caused to be distilled in a well coated Retort by degrees of Fire, giving at length a very strong one, then taking off the Vessel, we were not much sur∣prized to find, that the heat had here and there melted it, and that the fluxed Caput Mortuum had corroded the Glass, fetching off as 'twere films from it, and those parts which did not ap∣pear to the Eye thus manifestly wasted, seemed yet by their great brittleness, to have been penetrated, so that their Texture was spoiled by the saline and vitriolate Corpuscles.]

Prop II. Common Glass is not ordina∣rily permeable by Chymical Liquors, though strong and subtile, nor by the directly visible or odorable Expira∣tions of Bodies tho absolutely speaking it be pervious to some Corporeal Sub∣stances.
This Proposition consisting of two parts, we shall allow each of them its distinct Proofs.

And as for the first part, 'tis ma∣nifestly
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agreeable to the Common Experience of Chymists; who dai∣ly find, that in well stopt Vials, or at least in Hermetically seal'd Glasses, they can preserve their subtilest and most piercing Menstruums, as Spirit of Nitre, Aqua Fortis, Spirit of Salt, Spirit of Vinegar, and Oil of Vitriol. And this they find to be true, not only as to Acid and Corrosive Li∣quors, like those I have newly nam∣ed, but also in those Spirits that a∣bound with Fugitive Salts, as the Spirit of Urine, of Blood, and of Sal-Armoniack; and in the most sub∣tile & highly rectified Spirit of Wine; as also in the Ethereal Oil, or, as ma∣ny call it, Spirit, of Turpentine: as likewise in the Liquors of Salt of Tartar, and other fixt Alcalies re∣solved by Deliquium.

The Result of these Observa∣tions may be much confirmed by considering, how often it happens in the Destillation of more Wild and Fugitive Spirits, as of Nitre, Tar∣tar, and Sugar; that, though they
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are much agitated, and perhaps sub∣tilized, by Heat, yet, if the Lute, that joins the Receiver to the Retort be very firm & close, the Receivers, though large, are often broken in pieces; which probably would not happen, if the Spirits could insinuate & croud themselves, through the pores of Glass.

But, whereas it may be pretended, that such Vessels are strong and thick, I shall add, that I have had the Curiosity to cause very fine bubbles to be blown at the flame of a Lamp, purposly that they may be made extreamly thin, and of but a small part of the thickness we meet with in the Vessels made at the Glass house; and some of these I caus'd to be exactly stopt, and others to be Hermetically seal'd; but could not find, that either dry Salt of Tartar would relent in one, that was kept a good while under water, or that strong Spirit of Sal Armoniack, which is one of the subtilest Spirits that we know, would penetrate one of these thin films of Glass, which we kept
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a great while immersed in it, though to discover whether it would at all penetrate the thinnest Glasses, we employed some which were of that fine sort that is called Essence Vials.

These and some other Tryals have, I confess, made me very diffident of the Experiments, that have been delivered by some men of Note, and built upon by others, of the Permeableness of or∣dinary Glass Vessels to Chymical Li∣quors, as, that Mercury and Aqua fortis being digested together in a Bolt-head may, by rubbing the outside of the Glass, be made visibly and palpably to transudate. Which Experiment (if my Memory do not much de∣ceive me,) I purposely tryed with care, but without success.

But after all this I must desire, that it may be remembred, that in wording the Proposition of the Imper∣viousness of Glass, I intimated that I would have it understood of what Ordinarily happens. For in some Ex∣traordinary cases, which I take to be exceeding rare, I do not absolutely
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deny, but that the General rule may admit of Exceptions. And, if it be law∣ful to conjecture, these exceptions are likeliest to take place, when the peculiar Texture of this or that Glass, is more slight or lax than ordinary; or when the Bodies that are to pervade it, are ve∣hemently agitated by heat; or when, besides a great subtlety, and perhaps degree of heat too, their particles chance to have a special congruity, to the relaxed Pores of that particular Glass they are to pass through. I re∣member I have seen, not without some wonder, a sort of Glass of so soft and resoluble a Texture, that Vessels of it of a competent thickness, would be manifestly prejudiced and wrought upon by Liquors, that were not consi∣derably Sharp or Corrosive, if they were put in very hot. I have also heard of another sort of Glasses, made in a certain Forrest, complained of by a Destiller, as subject to be sometimes injured by Corrosive Liquors. I once knew a Doctor of Physick, that by divers credulous Alchymists was sus∣pected
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to have, what they call the Philosophers Stone, because of a cer∣tain Book, Ingenious enough, that he was supposed to have written on that subject. But when after some acquain∣tance I happened to debate his Princi∣ples freely with him, he confessed to me, that he had been mistaken, and to invite me to give him my thoughts upon such like works, he frankly made me an ingenuous relation of his Pro∣ceedings, wherein the main thing that dazled him, and kept him from seeing his Error, was, that he had reduced the matter he wrought on, which was real Gold, to that degree of Fusible∣ness and subtlety, that when he gave too strong a Fire, as mistake or curio∣sity made him several times do, the finer part of the Metal would sweat through his Glasses, and stick some∣times to the outside of them, and some∣times to the Neighbouring Bodies. And, when I objected, that he might be mistaken in this, and that what he thought had come forth by transu∣dation, rather issued out at some
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small unheeded crack, he replyed that he had made the observation so often, and with such care, that he was fully satisfied it was a real penetration of the Glass, by the attenuated Metal, which he was to have convinced me of by Tryal. But, before he could come to make it, by an Errour of his own he unhappily died.

But, whatever be judged of this penetrating Gold, I elsewhere relate, that I having upon a time destilled Spirit of Harts-horn with a very strong Fire, into a Receiver that was large and thick enough, but of a course kind of Glass, it did appear, upon my best examination, that the Glass itself was penetrated by some vehemently agitated Fumes, or some subtile Li∣quor, that setled in strongly scented drops on the outside of the Receiver. But such Instances being very rare, and happening but in some cases or conjunctures of circumstances, that are not like to be at all frequent, they cannot hinder the first part of our Proposition to be true, in
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the sense wherein 'tis laid down.

And, as to the second part of the Proposition, which asserts Glass to be pervious to some Corporeal substances, it may be proved ad hominem against any Epicurean that should deny it, and the Cartesians must not) by the free ingress and egress, which our seal'd Thermoscopes shew, that the Atoms or Corpuscles of Cold and Heat are allowed, through the Pores of the Glass, that contains the rising or fal∣lng Tincture, or other Liquor. And without proceeding upon the peculiar Principles of the Epicureans, we may give more certain proofs of the Per∣meableness of Glass by certain Bodies. For I have elsewhere manifestly e∣vinced that the Effluvia of a Load∣stone will attract and invigorate Steel, though inclosed in Hermetically seal'd Glasses; nay, I have also shewn by Ex∣periment, that the Effluvia of so gross and dull a Body as the Earth, are readily transmitted through Glass, and will operate on Iron, in Vessels hermeti∣cally sealed. If Light be, as probably
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'tis, either a subtile and rapidly mo∣ving Body, or at least require such an one for its Vehicle, it must not be de∣nied, that 'tis possible for a Body without difficulty to pass through the Pores of Glass; since 'tis by its help that we can clearly see the Dimensions, Shapes, and Colours of Bodies inclu∣ded in Glasses. To this I shall add, that far less subtile Bodies than those that constitute or convey Light, may be made to permeate Glass, if their Fi∣gures being congruous enough to the Pores of it, their penetration be assist∣ed by an impetuous motion, or a brisk impulse; as I have found by the increase of weight in some Metals, exposed for divers hours in Hermeti∣cally seal'd Glasses, to the action of a Flame. On which occasion I remem∣ber that having some years ago tryed the same Experiment with some Filings of Copper, they had indeed their colour much alter'd, being beautified with ex∣ceeding vivid Dyes, which they yet re∣tain, but did not evidently appear to be increased in weight, as if, because
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they were not of a Texture loose enough to be melted, the Igneous particles could not pierce them enough to stick fast in them, at least in num∣bers great enough, to amount to a sen∣sible weight.

But without the help of Fire, or any sensible Heat, I think it not impossible that Glass should be freely penetrated by some kind of Corpuscles, (though I do not yet know of what sort they are) that sometimes happen to roave about in the Air. This you will pro∣bably be surprized to read; but perhaps not more than I was at the Phaenomena that induce me to write it. But because these are very unusual, and can scarce be discoursed of without some odd reflections hinted by them, I thought fit to set down a Circumstan∣tial account of them in another Paper, to which it more directly belongs than to this Essay; and therefore shall now only tell you, what may be sufficient for my present purpose, namely, that having in two or three Vials closely stopt, kept a certain limpid and colour∣less
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Liquor, it would by fits acquire and lose a high Colour, though I could not reasonably impute the Changes to any manifest ones in the Air, nor to any other cause so proba∣ble, as the Ingress and Recess of some very subtle and uncommon particles, which at that time happened to swim to and fro in the Air, and now and then to invade, and sometimes to desert, the Liquor.

There is another sort of Experi∣ments relating to the Porosity of Glass, to shew that it may be pierced into by Bodies that are not corrosive in tast, and are not Liquors, but only have a forced and temporary Fluidity, if they have so much as that.

These Experiments may be drawn from some of the ways of colouring Panes of Glass, for the Windows of Churches and other buildings; I say, some of the ways, because, to deal can∣didly with you, I think, and so I pre∣sume will you ere long, that in di∣vers of those Glasses, the Colour doth not pierce at all deep into the Glass,
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but is produced by the close adhesion of a deep Red, but thin and transparent, Pigment, to the surface of a Glassy Plate, through both which the Beams of Light passing to the Eye, receive in their Passage the colour of the Pig∣ment.

But, as by some operations the Glass is rather Painted, or externally enamelled, than tinged, so in some others the Pigment or dying stuff ap∣pears to pierce a little beneath the very superficies of the Glass, and the Yellow Colour will not only go fur∣ther or deeper, but sometimes seems (for I do not yet positively affirm it) to penetrate the whole Glass from side to side.

The Methods of Painting and staining Glass, having been hitherto the Practices of a particular Trade that is gainful enough, and known but to few, the Artificers are wont to be shy of communicating their secrets, thô we know in general that Glass is stained, by having the Plates covered with Mineral Pigments, laid on Beds of
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beaten Lime, or some other conveni∣ent Powder, and kept for divers Hours in a strong fire, but yet not strong enough to make the Plates melt down, by which means the Pores of the Glass being much opened by the Heat, and the Pigments being likewise agitated, and some of them as it were vitrified with it, they are made either to pierce into the Plate, or at least to stick very closely and firmly to it. But because the Practices of Glass Painters require, besides skill and experience, a particular Furnace, and divers Im∣plements, I shall add, that to try, whe∣ther Glass may not, without so much ado, be so stained, as to shew it to be Porous, we took prepared Silver, (that Metal having, of all the Minerals I have tryed, the best Ingress into Glass) and having laid it upon a piece of Glass, not thick, nor yet so thin as to Melt very easily, we laid this Glass (with the Pigment uppermost) wa∣rily upon a few Quick-coals, and hav∣ing suffered it to neal a while we gave it about such a degree of heat, as might
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make and keep it red hot, without bringing it to compleat fusion, and then, suffering it to cool by degrees, we found, as we expected, that the Glass had acquired a Yellow, and al∣most Golden, Colour, which was not to be washed off, or to be taken a∣way, without such scraping as would injure or spoil the Glass it self. The way of preparing Silver for this ope∣ration, is not always the same, the Glass Painters commonly add to the calcined Silver some Mineral Bodies, as Antimony, Yellow Oker, or the like. But I, who take the penetration of the colour to proceed from the Silver it self, do sometimes imploy only some thin piece of Silver, such as an old Groat, upon which a little Sulphur being put, and kindled in the open Air, the Metal is presently calcined, and the Powder made use of. And this it self I do not so much out of ne∣cessity, as because the Calcination re∣duces the Metal into small parts, and gives it a form, that makes it more easy be laid on, as one thinks fit. For
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otherwise, going upon this my supposi∣tion, that the Silver was the true Pig∣ment of the Glass, I have more than once made Glass Yellow by Leaf-Sil∣ver laid flat on the surface of it, and a little moistened, to keep so light a Body from being blown off. And (to note that upon the by) 'tis pretty, that if the Fire be made too strong, which 'tis hard to avoid doing, when we will make it strong enough, with∣out the help of a Furnace, it has several times happened to me that the dyed Glass, though when held against the Light it appeared of a Golden or Yellow Colour, yet when held from the Light it appeared Blew, so that here we have in a Mineral, somewhat that is very like that we admire in the tin∣cture of Lignum Nephriticum, which shews almost the like difference of Co∣lour, as 'tis held against or from the Light, which may serve for a confir∣mation of what I have elsewhere said to shew that colours may be derived from Mechanical Principles: But that only upon the by. Whether the Gold
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colour produced by Silver, do favour the hopes of those Alchymists that work on that Metal, upon presump∣tion that 'tis but unripe Gold, 'tis im∣proper here to examine. But since Yellow is not the Colour of Silver, it seems the Yellowness, acquired by our Glass Plates, argues, that there has been some ingress of the substance of the particles of the Silver into the Glass, there appearing no way so ready, to give an account of the change of Colours, as by supposing the Particles of the Silver to be wrought on by the fixt Salts, and other fine parts, of the Glass; since we know, that Metals may afford differing colours, according to the Saline and other Bo∣dies that work upon them, as Copper with Spirit of Urine, which abounds in Volatile Salt, gives a deep Blew; with Spirit of Salt, a fair Green; and with Aqua fortis, a Colour that participates of both. And in the making of Glass of Lead with Minium and White-Sand, or Crystal, the Glass, it self if well made, is usually of an Amethystine Colour. But
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if you put a due Proportion, (which is a very small one,) of calcined Copper to it, this Metal will not communicate to the Glass its own reddishness, but be so changed by it, as to give it a good green, and sometimes so good an one, that pieces of this Glass, such as we have caused to be cut and set in Rings, might, among those that Judge of Stones but by the Eye, pass for no bad Emeraulds.

On this occasion, 'tis likely 'twill be asked, whether there be any way of tinging Glasses quite through, with a true and beautiful red, and whether the Art of dying Plates of Glass, which the windows of many old Churches shew to have formerly been practised, be now (as 'tis commonly supposed) altogether lost?

This Question, consisting of 2 Parts, I shall quickly dispatch; the former, by answering it without hesitancy in the affirmative. Yet adding withal, that the red tincture being communicated to Glass, not properly by mere penetra∣tion of the Pigment, but by the incor∣poration
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of it with Glass or its Materi∣als, by the help of fusion, I think the Experiment of no such great use in our present Inquiry, as to hinder me from reserving what I have observed about it to a more opportune place. And as to the second Part of the inqui∣ry, it being rather a Historical than a Philosophical question, I shall not here meddle with it; only I shall wish the question may be cautiously stated. For, upon the burning the famous Ca∣thedral of St. Pauls Church in Lon∣don, many pieces of the red Glass that adorned the windows, were found broken and scattered about, some of which I procur'd from a Chymist, that had carefully preserved them, design∣ing to retrieve the lost Invention of making the like. But when I came to examine them narrowly, I was confirmed in the suspicion I had, that the redness did not penetrate the whole Glass, but proceeded from a di∣aphanous Pigment very artificially laid on, for though in other Postures no such thing could be discerned, yet
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when I so held it, according to my Custom in examining painted Glasses, that the surfaces of the Plate lay in the same level with my Eye, between it and the window, so that a broken edge was next my Eye, I could plainly see, and made the Chymist himself see, the lower part of the Plate to be of ordinary uncoloured Glass, upon which there lay a very thin Plate or Bed of a Diaphanous red Pigment, which, though it were not easily, was not impossible to be here and there scraped off.

But, to return to those colorations that seem to pierce into the Pores of Glass, I remember that I had once oc∣casion to destil in a small Retort some Gold, amalgamed with such a fine and subtile Mercury, that being (without the addition of any Salt) put to the Gold in the cold, they presently grew hot together. And in the destillation of this uncommon mixture, I found the matter had, before it flew a way, permanently died or stained, about an Inch in Diameter of the bottom of the
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Glass, with a colour that, looked on from the Light, was like that of the better sort of Turquoises; but beheld when 'twas interposed between the Window and the Eye, appeared of a somewhat Golden colour. And this Glass, with some others oddly colored, I have yet by me to satisfy the Curi∣ous, though I cannot but give Adver∣tisement, that the colorations of Glass may be much better performed with such Plates, and in such Furnaces, as the Glass Painters use, than without them.

Since the Writing of the foregoing Paragraph, I was visited by an in∣dustrious person, much addicted to some Chymical Operations, who had formerly advised with me about a Pro∣cess, of which I had had some Expe∣rience, that he conceived might be use∣ful to him. I then acquainted him with some of my thoughts about it, and he having afterwards united Gold with Quick-Silver, (which by its Effects will be easily concluded not to have been common,) he kept them in Di∣gestion
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for some Months, & afterwards coming to me with a Melancholy look, told me that the Fire having been once immoderately increased in his absence, the sealed-Glass burst with an affrighting noise, and the included Amalgam was so strangely dissipated, that scarce the lest fragment of it could be retrieved. But the Decoction hav∣ing continued so long a time, it seems the matter was subtiliated enough to have a notable operation upon the Glass. For, though the upper part of the Bolt-glass were blown of, and shat∣tered into many pieces, yet the lower part scaped well enough, and when he brought it me, to observe what change had been made in it, I took notice with much delight, that the Glass seemed to be tinged throughout, with so fine and glorious a Red colour, that I have seen several Rubies themselves, in that point, inferiour to it.

FINIS.