Chapter III: Several kinds of Figures in Water frozen (1)

Putting fair Water into a large capacious Vessel of _Glass_, and exposing it to the cold, I observ’d after a little time, several broad, flat, and thin _laminæ_, or plates of _Ice_, crossing the bulk of the water and one another very irregularly, onely most of them seem’d to turn one of their edges towards that side of the Glass which was next it, and seem’d to grow, as ’twere from the inside of the Vessel inwards towards the middle, almost like so many blades of _Fern_. Having taken several of these plates out of water on the blade of a Knife, I observ’d them figur’d much after the manner of _Herring bones_, or _Fern blades_, that is, there was one bigger stem in the middle like the back-bone, and out of it, on either side, were a multitude of small _stiriæ_, or _icicles_, like the smaller bones, or the smaller branches in _Fern_, each of these branches on the one side, were parallel to all the rest on the same side, and all of them seem’d to make an angle with the stem, towards the top, of sixty degrees, and towards the bottom or root of this stem, of 120. See the fourth _Figure_ of the 8. _Plate_.

I observ’d likewise several very pretty Varieties of Figures in Water, frozen on the top of a broad flat Marble-stone, expos’d to the cold with a little Water on it, some like feathers, some of other shapes, many of them were very much of the shape exprest in the fifth Figure of the 8. _Scheme_, which is extremely differing from any of the other Figures.

I observ’d likewise, that the shootings of _Ice_ on the top of Water, beginning to freeze, were in streight _prismatical_ bodies much like those of _roch-peter_, that they crost each other usually without any kind of order or rule, that they were always a little higher then the surface of the Water that lay between them; that by degrees those _interjacent_ spaces would be fill’d with _Ice_ also, which usually would be as high as the surface of the rest.

In flakes of _Ice_ that had been frozen on the top of Water to any considerable thickness, I observ’d that both the upper and the under sides of it were curiously quill’d, furrow’d, or grain’d, as it were, which when the Sun shone on the Plate, was exceeding easily to be perceiv’d to be much after the shape of the lines in the 6. _Figure_ of the 8. _Scheme_, that is, they consisted of several streight ends of parallel Plates, which were of divers lengths and angles to one another without any certain order.

The cause of all which regular Figures (and of hundreds of others, namely of _Salts_, _Minerals_, _Metals_, &c. which I could have here inserted, would it not have been too long) seems to be deducible from the same Principles, which I have (in the 13. _Observation_) hinted only, having not yet had time to compleat a _Theory_ of them. But indeed (which I there also hinted) I judge it the second step by which the _Pyramid_ of natural knowledge (which is the knowledge of the form of bodies) is to be ascended: And whosoever will climb it, must be well furnish’d with that which the Noble _Verulam_ calls _Scalam Intellectus_; he must have scaling Ladders, otherwise the steps are so large and high, there will be no getting up them, and consequently little hopes of attaining any higher station, such as to the knowledge of the most simple principle of Vegetation manifested in Mould and Mushromes, which, as I elsewhere endeavoured to shew, seems to be the third step; for it seems to me, that the Intellect of man is like his body, destitute of wings, and cannot move from a lower to a higher and more sublime station of knowledg, otherwise then step by step, nay even there where the way is prepar’d and already made passible; as in the _Elements of Geometry_, or the like, where it is fain to climb a whole _series_ of Propositions by degrees, before it attains the knowledge of one _Probleme_. But if the ascent be high, difficult and above its reach, it must have recourse to a _novum organum_, some new engine and contrivance, some new kind of _Algebra_, or _Analytick Art_ before it can surmount it.

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Observ. XV. _Of _Kettering-stone_, and of the pores of _Inanimate_ bodies._

[13]This Stone which is brought from _Kettering_ in _Northampton-Shire_, and digg’d out of a Quarry, as I am inform’d, has a grain altogether admirable, nor have I ever seen or heard of any other stone that has the like. It is made up of an innumerable company of small bodies, not all of the same cize or shape, but for the most part, not much differing from a Globular form, nor exceed they one another in Diameter above three or four times; they appear to the eye, like the Cobb or Ovary of a _Herring_, or some smaller fishes, but for the most part, the particles seem somewhat less, and not so uniform; but their variation from a perfect globular ball, seems to be only by the pressure of the _contiguous_ bals which have a little deprest and protruded those toucht sides inward, and forc’d the other sides as much outwards beyond the limits of a Globe; just as it would happen, if a heap of exactly round Balls of soft Clay were heaped upon one another; or, as I have often seen a heap of small Globules of _Quicksilver_, reduc’d to that form by rubbing it much in a glaz’d Vessel, with some slimy or sluggish liquor, such as Spittle, when though the top of the upper Globules be very neer spherical, yet those that are prest upon by others, exactly imitate the forms of these lately mention’d grains.

Where these grains touch each other, they are so firmly united or settled together, that they seldom part without breaking a hole in one or th’other of them, such as a, a, a, b, c, c, &c. Some of which fractions, as a, a, a, a, where the touch has been but light, break no more then the outward crust, or first shell of the stone, which is of a white colour, a little dash’d with a brownish Yellow, and is very thin, like the shell of an Egg: and I have seen some of those grains perfectly resemble some kind of Eggs, both in colour and shape: But where the union of the _contiguous granules_ has been more firm, there the divulsion has made a greater Chasm, as at b, b, b, in so much that I have observ’d some of them quite broken in two, as at c, c, c, which has discovered to me a further resemblance they have to Eggs, they having an appearance of a white and yelk, by two differing substances that envelope and encompass each other.

That which we may call the white was pretty whitish neer the yelk, but more duskie towards the shell; some of them I could plainly perceive to be shot or radiated like a _Pyrites_ or _fire-stone_; the yelk in some I saw hollow, in others fill’d with a duskie brown and porous substance like a kind of pith.

The small pores, or _interstitia_ eeee betwixt the Globules, I plainly saw, and found by other trials to be every way pervious to air and water, for I could blow through a piece of this stone of a considerable thickness, as easily as I have blown through a Cane, which minded me of the pores which _Des Cartes_ allow his _materia subtilis_ between the _æthereal_ globules.

The object, through the _Microscope_, appears like a _Congeries_ or heap of Pibbles, such as I have often seen cast up on the shore, by the working of the Sea after a great storm, or like (in shape, though not colour) a company of small Globules of Quicksilver, look’d on with a _Microscope_, when reduc’d into that form by the way lately mentioned. And perhaps, this last may give some hint at the manner of the formation of the former: For supposing some _Lapidescent_ substance to be generated, or some way brought (either by some commixture of bodies in the Sea it self, or protruded in, perhaps, out of some _subterraneous_ caverns) to the bottom of the Sea, and there remaining in the form of a liquor like Quicksilver, _heterogeneous_ to the ambient _Saline_ fluid, it may by the working and tumblings of the Sea to and fro be jumbled and comminuted into such Globules as may afterwards be hardned into Flints, the lying of which one upon another, when in the Sea, being not very hard, by reason of the weight of the incompassing fluid, may cause the undermost to be a little, though not much, varied from a globular Figure. But this only by the by.

After what manner this _Kettering-stone_ should be generated I cannot learn, having never been there to view the place, and observe the circumstances; but it seems to me from the structure of it to be generated from some substance once more fluid, and afterwards by degrees growing harder, almost after the same manner as I supposed the generation of Flints to be made.

But whatever were the cause of its curious texture, we may learn this information from it; that even in those things which we account vile, rude, and coorse, Nature has not been wanting to shew abundance of curiosity and excellent Mechanisme.

We may here find a Stone by help of a _Microscope_, to be made up of abundance of small Balls, which do but just touch each other, and yet there being so many contacts, they make a firm hard mass, or a Stone much harder then Free-stone.

Next, though we can by a _Microscope_ discern so curious a shape in the particles, yet to the naked eye there scarce appears any such thing; which may afford us a good argument to think, that even in those bodies also, whose _texture_ we are not able to discern, though help’d with _Microscopes_, there may be yet _latent_ so curious a _Schematisme_, that it may abundantly satisfie the curious searcher, who shall be so happy as to find some way to discover it.

Next, we here find a Stone, though to the naked eye a very close one, yet every way perforated with innumerable pores, which are nothing else but the _interstitia_, between those multitudes of minute globular particles, that compose the bulk it self, and these pores are not only discover’d by the _Microscope_, but by this contrivance.

I took a pretty large piece of this stone, and covering it all over with cement, save only at two opposite parts, I found my self able, by blowing in at one end that was left open, to blow my spittle, with which I had wet the other end, into abundance of bubbles, which argued these pores to be open and pervious through the whole stone, which affords us a very pretty instance of the porousness of some seemingly close bodies, of which kind I shall anon have occasion to subjoyn many more, tending to prove the same thing.

I must not here omit to take notice, that in this body there is not a _vegetative_ faculty that should so contrive this structure for any peculiar use of _Vegetation_ or growth, whereas in the other instances of vegetable porous bodies, there is an _anima_ or _forma informans_, that does contrive all the Structures and _Mechanisms_ of the constituting body, to make them subservient and usefull to the great Work or Function they are to perform. And so I ghess the pores in Wood, and other vegetables, in bones, and other Animal substances, to be as so many channels, provided by the Great and Alwise Creator, for the conveyance of appropriated juyces to particular parts. And therefore, that this may tend, or be pervious all towards one part, and may have impediments, as valves or the like, to any other; but in this body we have very little reason so suspect there should be any such design, for it is equally pervious every way, not onely forward, but backwards, and side-ways, and seems indeed much rather to be _Homogeneous_ or similar to those pores, which we may with great probability believe to be the channels of _pellucid_ bodies, not directed, or more open any one way, then any other, being equally pervious every way. And, according as these pores are more or greater in respect of the _interstitial_ bodies, the more transparent are the so constituted concretes; and the smaller those pores are, the weaker is the _Impulse_ of light communicated through them, though the more quick be the progress.

Upon this Occasion, I hope it will not be altogether unseasonable, if I propound my conjectures and _Hypothesis_ about the _medium_ and conveyance of light.

I suppose then, that the greatest part of the _Interstitia_ of the world, that lies between the bodies of the Sun and Starrs, and the Planets, and the Earth, to be an exceeding fluid body, very apt and ready to be mov’d, and to communicate the motion of any one part to any other part, though never so far distant: Nor do I much concern my self, to determine what the Figure of the particles of this exceedingly subtile fluid _medium_ must be, nor whether it have any interstitiated pores or vacuities, it being sufficient to solve all the _Phænomena_ to suppose it an exceedingly fluid, or the most fluid body in the world, and as yet impossible to determine the other difficulties.

That being so exceeding fluid a body, it easily gives passage to all other bodies to move to and fro in it.

That it neither receives from any of its parts, or from other bodies; nor communicates to any of its parts, or to any other body, any impulse, or motion in a direct line, that is not of a determinate quickness. And that when the motion is of such determinate swiftness, it both receives, and communicates, or propagates an impulse or motion to any imaginable distance in streight lines, with an unimaginable celerity and vigour.

That all kind of solid bodies consist of pretty massie particles in respect of the particles of this fluid _medium_, which in many places do so touch each other, that none of this fluid _medium_ interposes much after the same manner (to use a gross similitude) as a heap of great stones compose one great _congeries_ or mass in the midst of the water.

That all fluid bodies which we may call _tangible_, are nothing but some more subtile parts of those particles, that serve to constitute all _tangible_ bodies.

That the water, and such other fluid bodies, are nothing but a _congeries_ of particles agitated or made fluid by it in the same manner as the particles of _Salt_ are agitated or made fluid by a parcel of water, in which they are dissolv’d, and subsiding to the bottom of it, constitute a fluid body, much more massie and dense, and less fluid then the pure water it self.

That the air on the other side is a certain company of particles of quite another kind, that is, such as are very much smaller, and more easily moveable by the motion of this fluid _medium_; much like those very subtile parts of _Cochenel_, other very deep tinging bodies, where by a very small parcel of matter is able to tinge and diffuse it self over a very great quantity of the fluid dissolvent; or somewhat after that manner, as smoak, and such like minute bodies, or steams, are observ’d to tinge a very great quantity of air; onely this last similitude is deficient in one propriety, and that is a perpetuity or continuance in that state of commixture with the air, but the former does more nearly approach to the nature and manner of the air’s being dissolv’d by this fluid or _Æther_. And this Similitude will further hold in these proprieties; that as those tinctures may be increased by certain bodies, so may they be precipitated by others, as I shall afterwards shew it to be very probable, that the like accidents happen even to the Air it self.

Further, as these solutions and tinctures do alter the nature of these fluid bodies, as to their aptness to propagate a motion or impulse through them, even so does the particles of the Air, Water, and other fluid bodies, and of Glass, Crystal, &c. which are commixt with this bulk of the _Æther_ alter the motion of the propagated pulse of light; that is, where these more bulkie particles are more plentifull, and consequently a lesser quantity of the _Æther_ between them to be mov’d, there the motion must necessarily be the swifter, though not so robust, which will produce those effects, which I have (I hope) with some probability, ascribed to it in the digression about Colours, at the end of the _Observations_ on _Muscovy-glass._

Now, that other Stones, and those which have the closest and hardest textures, and seem (as far as we are able to discover with our eyes, though help’d with the best _Microscopes_) freest from pores, are yet notwithstanding replenish’d with them, an Instance or two will, I suppose, make more probable.

A very solid and unflaw’d piece of cleer white _Marble_, if it be well polish’d and glaz’d, has so curiously smooth a surface, that the best and most polish’d surface of any wrought-glass, seems not to the naked eye, nor through a _Microscope_, to be more smooth, and less porous. And yet, that this hard close body is replenish’d with abundance of pores, I think these following Experiments will sufficiently prove.

The first is, That if you take such a piece, and for a pretty while boyl it in Turpentine and Oyl of Turpentine, you shall find that the stone will be all imbu’d with it; and whereas before it look’d more white, but more opacous, now it will look more greasie, but be much more transparent, and if you let it lie but a little while, and then break off a part of it, you shall find the unctuous body to have penetrated it to such a determinate depth every way within the surface. This may be yet easier try’d with a piece of the same _Marble_, a little warm’d in the fire, and then a little Pitch or Tarr melted on the top of it; for these black bodies, by their insinuating themselves into the invisible pores of the stone, ting it with so black a hue, that there can be no further doubt of the truth of this assertion, that it abounds with small imperceptible pores.

Now, that other bodies will also sink into the pores of _Marble_, besides unctuous, I have try’d, and found, that a very Blue tincture made in _spirit of Urine_ would very readily and easily sink into it, as would also several tinctures drawn with _spirit of Wine_.

Nor is _Marble_ the only seemingly close stone, which by other kinds of Experiments may be found porous; for I have by this kind of Experiment on divers other stones found much the same effect, and in some, indeed much more notable. Other stones I have found so porous, that with the _Microscope_ I could perceive several small winding holes, much like Worm-holes, as I have noted in some kind of _Purbeck-stone_, by looking on the surface of a piece newly flaw’d off, for if otherwise, the surface has been long expos’d to the Air, or has been scraped with any tool, those small caverns are fill’d with dust, and disappear.

And to confirm this _Conjecture_, yet further, I shall here insert an excellent account, given into the _Royal Society_ by that Eminently Learned Physician, Doctor _Goddard_, of an Experiment, not less instructive then curious and accurate, made by himself on a very hard and seemingly close stone call’d _Oculus Mundi_, as I find it preserv’d in the Records of that Honourable Society.

A small stone of the kind, call’d by some Authours, _Oculus Mundi_,
being dry and cloudy, weigh’d 5²⁰⁹⁄₂₅₆ _Grains_.

The same put under water for a night, and somewhat more, became
transparent, and the superficies being wiped dry, weighed 6³⁄₂₅₆
_Grains_.

The difference between these two weights, 0⁵⁰⁄₂₅₆ of a _Grain_.

The same Stone kept out of water one Day and becoming cloudy again
weighed, 5²²⁵⁄₂₅₆ _Graines_.

Which was more then the first weight, 0¹⁶⁄₂₅₆ of a _Grain_.

The same being kept two Days longer weighed, 5²⁰²⁄₂₅₆ _Graines_.

Which was less then at first, 0⁷⁄₂₅₆ a _Grain_.

Being kept dry something longer it did not grow sensibly lighter.

Being put under water for a night and becoming again transparent and
wiped dry, the weight was, _6³⁄₂₅₆ Grains_, the same with the first
after putting in water, and more then the last weight after keeping of
it dry, 0⁵⁷⁄₂₅₆ of a _Grain_.

Another Stone of the same kind being variegated with milky _white_ and
_gray_ like some sorts of _Agates_, while it lay under water, was
alwaies invironed with little Bubbles, such as appear in water a little
before boyling, next the sides of the Vessel.

There were also some the like Bubbles on the Surface of the water just
over it, as if either some exhalations came out of it, or that it did
excite some fermentation in the parts of the water contiguous to it.

There was little sensible difference in the transparency of this Stone,
before the putting under water, and after: To be sure the milky-_white_
parts continued as before, but more difference in weight then in the
former. For whereas before the putting into the water the weight was
18⁹⁷⁄₁₂₈ _Graines_. After it had lyen in about four and twenty hours
the weight was 20²⁷⁄₁₂₈ _Graines_, so the difference was, 1⁵⁸⁄₁₂₈
_Graines_.

The same Stone was infused in the water scalding hot, and so continued
for a while after it was cold, but got no more weight then upon
infusing in the cold, neither was there any sensible Difference in the
weight both times.

In which Experiment, there are three Observables that seem very manifestly to prove the porousness of these seemingly close bodies: the first is their acquiring a transparency, and losing their whiteness after steeping in water, which will seem the more strongly to argue it, if what I have already said about the making transparent, or clarifying of some bodies, as the white powder of beaten Glass, and the froth of some glutinous transparent liquor be well consider’d; for thereby it will seem rational to think that this transparency arises from the insinuation of the water (which has much the same refraction with such stony particles, as may be discover’d by Sand view’d with a _Microscope_) into those pores which were formerly repleat with air (that has a very differing refraction, and consequently is very reflective) which seems to be confirm’d by the second Observable, namely, the increase of weight after keeping, and decrease upon drying. And thirdly, seem’d yet more sensibly confirm’d by the multitude of bubbles in the last Experiment.

We find also most Acid Salts very readily to dissolve and separate the parts of this body one from another; which is yet a further Argument to confirm the porousness of bodies, and will serve as such, to shew that even Glass also has an abundance of pores in it, since there are several liquors, that with long staying in a Glass, will so _Corrode_ and eat into it, as at last, to make it pervious to the liquor it contain’d, of which I have seen very many Instances.

Since therefore we find by other proofs, that many of those bodies which we think the most solid ones, and appear so to our sight, have notwithstanding abundance of those grosser kind of pores, which will admit several kinds of liquors into them, why should we not believe that Glass, and all other transparent bodies abound with them, since we have many other arguments, besides the propagation of light, which seem to argue for it?

And whereas it may be objected, that the propagation of light is no argument that there are those atomical pores in glass, since there are _Hypotheses_ plausible enough to solve those _Phænomena_, by supposing the pulse onely to be communicated through the transparent body.

To this I answer, that that _Hypothesis_ which the industrious _Mersennus_ has publish’d about the slower motion of the end of a Ray in a denser _medium_, then in a more rare and thin, seems altogether unsufficient to solve abundance of _Phænomena_, of which this is not the least considerable, that it is impossible from that supposition, that any colours should be generated from the refraction of the Rays; for since by that _Hypothesis_ the _undulating pulse_ is always carried perpendicular, or at right angles with the Ray or Line of direction, it follows, that the stroke of the pulse of light, after it has been once or twice refracted (through a Prisme, for example) must affect the eye with the same kind of stroke as if it had not been refracted at all. Nor will it be enough for a Defendant of that _Hypothesis_, to say, that perhaps it is because the refractions have made the Rays more weak, for if so, then two refractions in the two parallel sides of a _Quadrangular Prisme_ would produce colours, but we have no such _Phænomena_ produc’d.

There are several Arguments that I could bring to evince that there are in all transparent bodies such atomical pores. And that there is such a fluid body as I am arguing for, which is the _medium_, or Instrument, by which the pulse of Light is convey’d from the _lucid body_ to the enlightn’d. But that it being a digression from the Observations I was recording, about the Pores of _Kettering-Stone_, it would be too much such, if I should protract it too long; and therefore I shall proceed to the next _Observation_.

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Observ. XVI. _Of _Charcoal_, or burnt _Vegetables_._

Charcoal, or a Vegetable burnt black, affords an object no less pleasant than instructive, for if you take a small round Charcoal, and break it short with your fingers, you may perceive it to break with a very smooth and sleek surface, almost like the surface of black sealing Wax; this surface, if it be look’d on with an ordinary _Microscope_, does manifest abundance of those pores which are also visible to the eye in many kinds of _Wood_, rang’d round the pith, both a in kind of circular order, and a radiant one. Of these there are a multitude in the substance of the Coal, every where almost perforating and drilling it from end to end; by means of which, be the Coal never so long, you may easily blow through it; and this you may presently find, by wetting one end of it with Spittle, and blowing at the other.

But this is not all, for besides those many great and conspicuous irregular spots or pores, if a better _Microscope_ be made use of, there will appear an infinite company of exceedingly small, and very regular pores, so thick and so orderly set, and so close to one another, that they leave very little room or space between them to be fill’d with a solid body, for the apparent _interstitia_ or separating sides of these pores seem so thin in some places, that the texture of a Honey-comb cannot be more porous. Though this be not every where so, the intercurrent partitions in some places being very much thicker in proportion to the holes.

Most of these small pores seem’d to be pretty round, and were rang’d in rows that radiated from the pith to the bark; they all of them seem’d to be continued open pores, running the whole length of the Stick; and that they were all perforated, I try’d by breaking off a very thin sliver of the Coal cross-ways, and then with my _Microscope_, diligently surveying them against the light, for by that means I was able to see quite through them.

These pores were so exceeding small and thick, that in a line of them, ¹⁄₁₈ part of an Inch long, I found by numbering them no less then 150. small pores; and therefore in a line of them an Inch long, must be no less then 2700. pores, and in a circular _area_ of an Inch diameter, must be about 5725350. of the like pores; so that a Stick of an Inch Diameter, may contain no less then seven hundred and twenty five thousand, besides 5 Millions of pores, which would, I doubt not, seem even incredible, were not every one left to believe his own eyes. Nay, having since examin’d _Cocus, black and green Ebony, Lignum Vitæ_, &c. I found, that all these Woods have their pores, abundantly smaller then those of soft light Wood; in so much, that those of _Guajacum_ seem’d not above an eighth part of the bigness of the pores of Beech, but then the _Interstitia_ were thicker; so prodigiously curious are the contrivances, pipes, or sluces by which the _Succus nutritius_, or Juyce of a Vegetable is convey’d from place to place.

This _Observation_ seems to afford us the true reason of several _Phænomena_ of Coals; as

First, why they look black; and for this we need go no further then the _Scheme_, for certainly, a body that has so many pores in it as this is discover’d to have, from each of which no light is reflected, must necessarily look black, especially, when the pores are somewhat bigger in proportion to the intervals then they are cut in the _Scheme_, black being nothing else but a privation of Light, or a want of reflection; and wheresoever this reflecting quality is deficient, there does that part look black, whether it be from a porousness of the body, as in this Instance, or in a deadning and dulling quality, such as I have observ’d in the _Scoria_ of Lead, Tin, Silver, Copper, &c.

Next, we may also as plainly see the reason of its shining quality, and that is from the even breaking off of the stick, the solid _interstitia_ having a regular termination or surface, and having a pretty strong reflecting quality, the many small reflections become united to the naked eye, and make a very pretty shining surface.

Thirdly, the reason of its hardness and brittleness seems evident, for since all the watery or liquid substance that moistn’d and toughn’d those _Interstitia_ of the more solid parts, are evaporated and remov’d, that which is left behind becomes of the nature almost of a stone, which will not at all, or very little, bend without a _divulsion_ or _solution_ of its _continuity_.

It is not my design at present, to examine the use and _Mechanisme_ of these parts of Wood, that being more proper to another Enquiry; but rather to hint, that from this Experiment we may learn,

First, what is the cause of the blackness of many burnt bodies, which we may find to be nothing else but this; that the heat of the fire agitating and rarifying the waterish, transparent, and volatile water that is contain’d in them, by the continuation of that action, does so totally expel and drive away all that which before fill’d the pores, and was dispers’d also through the solid mass of it, and thereby caus’d an universal kind of transparency, that it not onely leaves all the pores empty, but all the _Interstitia_ also so dry and _opacous_, and perhaps also yet further perforated, that that light onely is reflected back which falls upon the very outward edges of the pores, all they that enter into the pores of the body, never returning, but being lost in it.

Now, that the Charring or coaling of a body is nothing else, may be easily believ’d by one that shall consider the means of its production, which may be done after this, or any such manner. The body to be charr’d or coal’d, may be put into a _Crucible_, Pot, or any other Vessel that will endure to be made red-hot in the fire without breaking, and then cover’d over with Sand, so as no part of it be suffer’d to be open to the Air, then set into a good fire, and there kept till the Sand has continu’d red hot for a quarter, half, an hour or two, or more, according to the nature and bigness of the body to be coal’d or charr’d, then taking it out of the fire, and letting it stand till it be quite cold, the body may be taken out of the Sand well charr’d and cleans’d of its waterish parts; but in the taking of it out, care must be had that the Sand be very neer cold, for else, when it comes into the free air, it will take fire, and readily burn away.

This maybe done also in any close Vessel of Glass, as a _Retort_, or the like, and the several fluid substances that come over may be receiv’d in a fit _Recipient_, which will yet further countenance this _Hypothesis_: And their manner of charring Wood in great quantity comes much to the same thing, namely, an application of a great heat to the body, and preserving it from the free access of the devouring air; this may be easily learn’d from the History of Charring of Coal, most excellently describ’d and publish’d by that most accomplish’d Gentleman, Mr. _John Evelin_, in the 100, 101, 103, pages of his _Sylva_, to which I shall therefore refer the curious Reader that desires a full information of it.

Next, we may learn what part of the Wood it is that is the _combustible_ matter, for since we shall find that none, or very little of those fluid substances that are driven over into the Receiver are _combustible_, and that most of that which is left behind is so, it follows, that the solid _interstitia_ of the Wood are the _combustible_ matter. Further, the reason why uncharr’d Wood burns with a greater flame then that which is charr’d, is as evident, because those waterish or volatil parts issuing out of the fired Wood, every way, not onely shatter and open the body, the better for the fire to enter, but issuing out in vapours or wind, they become like so many little _æolipiles_, or Bellows, whereby they blow and agitate the fir’d part, and conduce to the more speedy and violent consumption or dissolution of the body.

Thirdly, from the Experiment of charring of Coals (whereby we see that notwithstanding the great heat, and the duration of it, the solid parts of the Wood remain, whilest they are preserv’d from the free access of the air undissipated) we may learn, that which has not, that I know of, been publish’d or hinted, nay, not so much as thought of, by any; and that in short is this.

First, _that the Air_ in which we live, move, and breath, and which encompasses very many, and cherishes most bodies it encompasses, that this Air is the _menstruum_, or universal dissolvent of all _Sulphureous_ bodies.

Secondly, _that this action_ it performs not, till the body be first sufficiently heated, as we find requisite also to the dissolution of many other bodies by several other _menstruums_.

Thirdly, _that this action_ of dissolution, produces or generates a very great heat, and that which we call Fire; and this is common also to many dissolutions of other bodies, made by _menstruums_, of which I could give multitudes of Instances.

Fourthly, _that this action_ is perform’d with so great a violence, and does so minutely act, and rapidly agitate the smallest parts of the _combustible_ matter, that it produces in the _diaphanous medium_ of the Air, the action or pulse of light, which what it is, I have else-where already shewn.

Fifthly, _that the dissolution_ of sulphureous bodies is made by a substance inherent, and mixt with the Air, that is like, if not the very same, with that which is fixt in _Salt-peter_, which by multitudes of Experiments that may be made with _Salt-peter_, will, I think, most evidently be demonstrated.

Sixthly, _that in this dissolution_ of bodies by the Air, a certain part is united and mixt, or dissolv’d and turn’d into the Air, and made to fly up and down with it in the same manner as a _metalline_ or other body dissolved into any _menstruums_, does follow the motions and progresses of that _menstruum_ till it be precipitated.

Seventhly, That as there is one part that is dissoluble by the Air, so are there other parts with which the parts of the Air mixing and uniting, do make a _Coagulum_, or _precipitation_, as one may call it, which causes it to be separated from the Air, but this _precipitate_ is so light, and in so small and rarify’d or porous clusters, that it is very volatil, and is easily carry’d up by the motion of the Air, though afterwards, when the heat and agitation that kept it rarify’d ceases, it easily condenses, and commixt with other indissoluble parts, it sticks and adheres to the next bodies it meets withall; and this is a certain _Salt_ that may be extracted out of _Soot_.

Eighthly, that many indissoluble parts being very apt and prompt to be rarify’d, and so, whilest they continue in that heat and agitation, are lighter then the Ambient Air, are thereby thrust and carry’d upwards with great violence, and by that means carry along with them, not onely that _Saline concrete_ I mention’d before, but many terrestrial, or indissoluble and irrarefiable parts, nay, many parts also which are dissoluble, but are not suffer’d to stay long enough in a sufficient heat to make them prompt and apt for that action. And therefore we find in _Soot_, not onely a part, that being continued longer in a competent heat, will be dissolv’d by the Air, or take fire and burn; but a part also which is fixt, terrestrial, and irrarefiable.

Ninthly, that as there are these several parts that will rarifie and fly, or be driven up by the heat, so are there many others, that as they are indissoluble by the _aerial menstruum_, so are they of such sluggish and gross parts, that they are not easily rarify’d by heat, and therefore cannot be rais’d by it; the volatility or fixtness of a body seeming to consist only in this, that the one is of a texture, or has component parts that will be easily rarify’d into the form of Air, and the other, that it has such as will not, without much ado, be brought to such a constitution; and this is that part which remains behind in a white body call’d Ashes, which contains a substance, or _Salt_, which Chymists call _Alkali_: what the particular natures of each of these bodies are, I shall not here examine, intending it in another place, but shall rather add that this _Hypothesis_ does so exactly agree with all _Phænomena_, of Fire, and so genuinely explicate each particular circumstance that I have hitherto observ’d, that it is more then probable, that this cause which I have assign’d is the true adequate, real, and onely cause of those _Phænomena_; And therefore I shall proceed a little further, to shew the nature and use of the Air.

Tenthly, therefore the dissolving parts of the Air are but few, that is, it seems of the nature of those _Saline menstruums_, or spirits, that have very much flegme mixt with the spirits, and therefore a small parcel of it is quickly glutted, and will dissolve no more; and therefore unless some fresh part of this _menstruum_ be apply’d to the body to be dissolv’d, the action ceases, and the body leaves to be dissolv’d and to shine, which is the Indication of it, though plac’d or kept in the greatest heat; whereas _Salt-peter_ is a _menstruum_, when melted and red-hot, that abounds more with those Dissolvent particles, and therefore as a small quantity of it will dissolve a great sulphureous body, so will the dissolution be very quick and violent.

Therefore in the _Eleventh_ place, it is observable, that, as in other solutions, if a copious and quick supply of fresh _menstruum_, though but weak, be poured on, or applied to the dissoluble body, it quickly consumes it: So this _menstruum_ of the Air, if by Bellows, or any other such contrivance, it be copiously apply’d to the shining body, is found to dissolve it as soon, and as violently as the more strong _menstruum_ of melted _Nitre_.

Therefore twelfthly, it seems reasonable to think that there is no such thing as an Element of Fire that should attract or draw up the flame, or towards which the flame should endeavour to ascend out of a desire or appetite of uniting with that as its _Homogeneal_ primitive and generating Element; but that that shining transient body which we call _Flame_, is nothing else but a mixture of Air, and volatil sulphureous parts of dissoluble or combustible bodies, which are acting upon each other whilst they ascend, that is, flame seems to be a mixture of Air, and the combustible volatil parts of any body, which parts the encompassing Air does dissolve or work upon, which action, as it does intend the heat of the _aerial_ parts of the dissolvent, so does it thereby further rarifie those parts that are acting, or that are very neer them, whereby they growing much lighter then the heavie parts of that _Menstruum_ that are more remote, are thereby protruded and driven upward; and this may be easily observ’d also in dissolutions made by any other _menstruum_, especially such as either create heat or bubbles. Now, this action of the _Menstruum_, or _Air_, on the dissoluble parts, is made with such violence, or is such, that it imparts such a motion or pulse to the _diaphanous_ parts of the Air, as I have elsewhere shewn is requisite to produce light.

This _Hypothesis_ I have endeavoured to raise from an Infinite of Observations and Experiments, the process of which would be much too long to be here inserted, and will perhaps another time afford matter copious enough for a much larger Discourse, the Air being a Subject which (though all the world has hitherto liv’d and breath’d in, and been unconversant about) has yet been so little truly examin’d or explain’d, that a diligent enquirer will be able to find but very little information from what has been (till of late) written of it: But being once well understood, it will, I doubt not, inable a man to render an intelligible, nay probable, if not the true reason of all the _Phænomena_ of Fire, which, as it has been found by Writers and Philosophers of all Ages a matter of no small difficulty, as may be sufficiently understood by their strange _Hypotheses_, and unintelligible Solutions of some few _Phænomena_ of it; so will it prove a matter of no small concern and use in humane affairs, as I shall elsewhere endeavour to manifest when I come to shew the use of the Air in respiration, and for the preservation of the life, nay, for the conservation and restauration of the health and natural constitution of mankind as well as all other aereal _animals_, as also the uses of this principle or propriety of the Air in chymical, mechanical, and other operations. In this place I have onely time to hint an _Hypothesis_, which, if God permit me life and opportunity, I may elsewhere prosecute, improve and publish. In the mean time, before I finish this Discourse, I must not forget to acquaint the Reader, that having had the liberty granted me of making some trials on a piece of _Lignum fossile_ shewn to the Royal Society, by the eminently Ingenious and Learned Physician, Doctor _Ent_, who receiv’d it for a Present from the famous _Ingenioso Cavalliero de Pozzi_, it being one of the fairest and best pieces of _Lignum fossile_ he had seen; Having (I say) taken a small piece of this Wood, and examin’d it, I found it to burn in the open Air almost like other Wood, and insteed of a resinous smoak or fume, it yielded a very bituminous one, smelling much of that kind of sent: But that which I chiefly took notice of, was, that cutting off a small piece of it, about the bigness of my Thumb, and charring it in a _Crucible_ with Sand, after the manner I above prescrib’d, I found it infinitely to abound with the smaller sort of pores, so extreamly thick, and so regularly perforating the substance of it long-ways, that breaking it off across, I found it to look very like an Honey-comb; but as for any of the second, or bigger kind of pores, I could not find that it had any; so that it seems, whatever were the cause of its production, it was not without those small kind of pores which we have onely hitherto found in Vegetable bodies: and comparing them with the pores which I have found in the Charcoals that I by this means made of several other kinds of Wood, I find it resemble none so much as those of Firr, to which it is not much unlike in grain also, and several other proprieties.

And therefore, what ever is by some, who have written of it, and particularly by _Francisco Stelluto_, wrote a Treatise in _Italian_ of that Subject, which was Printed at _Rome_, 1637, affirm’d that it is a certain kind of Clay or Earth, which in tract of time is turn’d into Wood; I rather suspect the quite contrary, that it was at first certain great Trees of Fir or Pine, which by some Earthquake, or other casualty, came to be buried under the Earth, and was there, after a long time’s residence (according to the several natures of the encompassing adjacent parts) either rotted and turn’d into a kind of Clay, or _petrify’d_ and turn’d into a kind of Stone, or else had its pores fill’d with certain Mineral juices, which being stay’d in them, and in tract of time coagulated, appear’d, upon cleaving out, like small Metalline Wires, or else from some flames or scorching forms that are the occasion oftentimes, and usually accompany Earthquakes, might be blasted and turn’d into Coal, or else from certain _subterraneous_ fires which are affirm’d by that Authour to abound much about those parts (namely, in a Province of _Italy_, call’d _Umbria_, now the _Dutchie_ of _Spoletto_, in the Territory of _Todi_, anciently call’d _Tudor_; and between the two Villages of _Collesecco_ and _Rosaro_ not far distant from the high-way leading to _Rome_, where it is found in greater quantity then elsewhere) are by reason of their being encompassed with Earth, and so kept close from the dissolving Air, charr’d and converted into Coal. It would be too long a work to describe the several kinds of pores which I met withall, and by this means discovered in several other Vegetable bodies; nor is it my present design to expatiate upon Instances of the same kind, but rather to give a Specimen of as many kinds as I have had opportunity as yet of observing, reserving the prosecution and enlarging on particulars till a more fit opportunity; and in prosecution of this design, I shall here add:

* * * * *

Observ. XVII. _Of _Petrify’d wood_, and other _Petrify’d bodies_._

Of this sort of substance, I observ’d several pieces of very differing kinds, both for their outward shape, colour, grain, _texture_, hardness, &c. some being brown and reddish; others gray, like a Hone; others black, and Flint-like: some soft, like a Slate or Whetstone, others as hard as a Flint, and as brittle. That which I more particular examin’d, was a piece about the bigness of a mans hand, which seem’d to have been a part of some large tree, that by rottenness had been broken off from it before it began to be _petrify’d_.

And indeed, all that I have yet seen, seem to have been rotten Wood before the petrifaction was begun; and not long since, examining and viewing a huge great _Oak_, that seem’d with meer age to be rotten as it stood, I was very much confirm’d in this opinion; for I found, that the grain, colour, and shape of the Wood, was exactly like this _petrify’d_ substance; and with a _Microscope_, I found, that all those _Microscopical_ pores, which in sappy or firm and sound Wood are fill’d with the natural or innate juices of those Vegetables, in this they were all empty, like those of _Vegetables charr’d_; but with this difference, that they seem’d much larger then I have seen any in _Charcoals_; nay, even then those of Coals made of great blocks of Timber, which are commonly call’d _Old-coals_.

The reason of which difference may probably be, that the charring of Vegetables, being an operation quickly perform’d, and whilest the Wood is sappy, the more solid parts may more easily shrink together, and contract the pores or _interstitia_ between them, then in the rotten Wood, where that natural juice seems onely to be wash’d away by _adventitious_ or unnatural moisture; and so though the natural juice be wasted from between the firm parts, yet those parts are kept asunder by the _adventitious_ moystures, and so by degrees settled in those postures.

And this I likewise found in the _petrify’d_ Wood, that the pores were somewhat bigger then those of _Charcoal_, each pore being neer upon half as bigg again, but they did not bear that disproportion which is exprest in the tenth _Scheme_, between the small specks or pores in the first Figure (which representeth the pores of Coal or Wood charr’d) and the black spots of the second Figure (which represent the like _Microscopical pores_ in the _petrify’d_ Wood) for these last were drawn by a _Microscope_ that magnify’d the object above six times more in Diameter then the _Microscope_ by which those pores of Coal were observ’d.

Now, though they were a little bigger, yet did they keep the exact figure and order of the pores of Coals and of rotten Wood, which last also were much of the same cize.

The other Observations on this _petrify’d_ substance, that a while since, by the appointment of the _Royal Society_, I made, and presented to them an account of, were these that follow, which had the honour done them by the most accomplish’d Mr. _Evelin_, my highly honoured friend, to be inserted and published among those excellent Observations wherewith his _Sylva_ is replenish’d, and would therefore have been here omitted, had not the Figure of them, as they appear’d through the _Microscope_ been before that engraven.

This _Petrify’d_ substance resembled Wood, in that

First, all the parts of it seem’d not at all _dislocated_, or alter’d from their natural Position, whil’st they were Wood, but the whole piece retain’d the exact shape of Wood, having many of the conspicuous pores of wood still remaining pores, and shewing a manifest difference visible enough between the grain of the Wood and that of the bark, especially when any side of it was cut smooth and polite; for then it appear’d to have a very lovely grain, like that of some curious close Wood.

Next (it resembled Wood) in that all the smaller and (if I may so call those which are onely visible with a good magnifying Glass) _Microscopical_ pores of it appear (both when the substance is cut and polish’d _transversly_ and _parallel_ to the pores of it) perfectly like the _Microscopical_ pores of several kinds of Wood, especially like and equal to those of several sorts of rotten Wood which I have since observ’d, retaining both the shape, position and magnitude of such pores. It was differing from Wood:

First; in _weight_, being to common water as 3¼ to 1. whereas there are few of our _English_ Woods, that when very dry are found to be full as heavie as water.

Secondly, in _hardness_, being very neer as hard as a Flint; and in some places of it also resembling the grain of a Flint: and, like it, it would very readily cut Glass, and would not without difficulty, especially in some parts of it, be scratch’d by a black hard Flint: It would also as readily strike fire against a Steel, or against a Flint, as any common Flint.

Thirdly, in the _closeness_ of it, for though all the _Microscopical_ pores of this _petrify’d_ substance were very conspicuous in one position, yet by altering that position of the polish’d surface to the light, it was also manifest, that those pores appear’d darker then the rest of the body, onely because they were fill’d up with a more duskie substance, and not because they were hollow.