much bigger then really they are and this may be in good part removed by putting the drop under the surface of clear Water for by that means most part of the refraction of the convex Surface of the drop is destroyed and the bubbles will appear much smaller And this by the by minds me of the appearing magnitude of the aperture of the iris or pupil of the eye which though it appear and be therefore judged very large is yet not above a quarter of the bigness it appears of by the lenticular refraction of the Cornea The cause of all which Phaenomena I imagine to be no other then this That the Parts of the Glass being by the excessive heat of the fire kept off and separated one from another and thereby put into a kind of sluggish fluid consistence are suffered to drop off with that heat or agitation remaining in them into cold Water by which means the outsides of the drop are presently cool'd and crusted and are thereby made of a loose texture because the parts of it have not time to settle themselves leisurely together and so to lie very close together And the innermost parts of the drop retaining still much of their former heat and agitations remain of a loose texture also and according as the cold strikes inwards from the bottom and sides are quenched as it were and made rigid in that very posture wherein the cold finds them For the parts of the crust being already hardened will not suffer the parts to shrink any more from the outward Surface inward and though it shrink a little by reason of the small parcels of some Aerial substances dispersed through the matter of the Glass yet that is not neer so much as it appears as I just now hinted nor if it were would it be sufficient for to consolidate and condense the body of Glass into a tuff and close texture after it had been so excessively rarified by the heat of the glass-Furnace But that there may be such an expansion of the aerial substance contained in those little blebbs or bubbles in the body of the drop this following Experiment will make more evident Take a small Glass-Cane about a foot long seal up one end of it hermetically then put in a very small bubble of Glass almost of the shape of an Essence-viol with the open mouth towards the sealed end then draw out the other end of the Pipe very small and fill the whole Cylinder with water then set this Tube by the Fire till the Water begin to boyl and the Air in the bubble be in good part rarified and driven out then by sucking at the smalling Pipe more of the Air or vapours in the bubble may be suck'd out so that it may sink to the bottom when it is sunk to the bottom in the flame of a Candle or Lamp nip up the slender Pipe and let it cool whereupon it is obvious to observe first that the Water by degrees will subside and shrink into much less room Next that the Air or vapours in the Glass will expand themselves so as to buoy up the little Glass Thirdly that all about the inside of the Glass-pipe there will appear an infinite number of small bubbles which as the Water grows colder and colder will swell bigger and bigger and many of them buoy themselves up and break at the top From this Disceding of the heat in Glass drops that is by the quenching or cooling Irradiations propagated from the Surface upwards and inwards by the lines CT CT DT DE c. the bubbles in the drop have room to expand themselves a little and the parts of the Glass contract themselves but this operation being too quick for the sluggish parts of the Glass the contraction is performed very unequally and irregularly and thereby the Particles of the Glass are bent some one way and some another yet so as that most of them draw towards the Pith or middle TEEE or rather from that outward so that they cannot extricate or unbend themselves till some part of TEEE be broken and loosened for all the parts about that are placed in the manner of an Arch and so till their hold at TEEE be loosened they cannot fly asunder but uphold and shelter and fix each other much like the stones in a Vault where each stone does concurre to the stability of the whole Fabrick and no one stone can be taken away but the whole Arch falls And wheresoever any of those radiating wedges DTD c. are removed which are the component parts of this Arch the whole Fabrick presently falls to pieces for all the Springs of the several parts are set at liberty which immediately extricate themselves and fly asunder every way each part by its spring contributing to the darting of it self and some other contiguous part But if this drop be heat so hot as that the parts by degrees can unbend themselves and be settled and annealed in that posture and be then suffered gently to subside and cool The parts by this nealing losing their springiness constitute a drop of a more soft but less brittle texture and the parts being not at all under a flexure though any part of the middle or Pith TEEE be broken yet will not the drop at all fly to pieces as before This Conjecture of mine I shall indeavour to make out by explaining each particular Assertion with analogous Experiments The Assertions are these First That the parts of the Glass whilst in a fluid Consistence and hot are more rarified or take up more room then when hard and cold Secondly That the parts of the drop do suffer a twofold contraction Thirdly That the dropping or quenching the glowing metal in the Water makes it of a hard springing and rarified texture Fourthly That there is a flexion or force remaining upon the parts of the Glass thus quenched from which they indeavour to extricate themselves Fifthly That the Fabrick of the drop that is able to hinder the parts from extricating themselves is analogus to that of an Arch. Sixthly That the sudden flying asunder of the parts proceeds from their springiness Seventhly That a gradual heating and cooling does anneal or reduce the parts of Glass to a texture that is more loose and easilier to be broken but not so brittle That the first of these is true may be gathered from this That Heat is a property of a body arising from the motion or agitation of its parts and therefore whatever body is thereby toucht must necessarily receive some part of that motion whereby its parts will be shaken and agitated and so by degrees free and extricate themselves from one another and each part so moved does by that motion exert a conatus of protruding and displacing all the adjacent Particles Thus Air included in a vessel by being heated will burst it to pieces Thus have I broke a Bladder held over the fire in my hand with such a violence and noise
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 â—pacous and perhaps also yet further persorated 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 Cracible 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 may be 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. Iohn 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 aeolipiles or Bellows whereby they blow and agitate the fir'd part and conduce to the more speedy and violent comsumption 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 Saltpeter 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 dissolv'd 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
Bubbles made with any other transparent Substance Thus have I produced them with Bubbles of Pitch Rosin Câ—lophony Turpentine Solutions of several Gums as 〈◊〉 Arabick in water any glutinous Liquor as Wort Wine Spirit of Wine Oyl of Turpentine Glare of Snails c. It would be needless to enumerate the several Instances these being enough to shew the generality or universality of this propriety Only I must not omit that we have instances also of this kind even in metalline Bodies and animal for those several Colours which are observed to follow each other upon the polisht surface of hardned Steel when it is by a sufficient degree of heat gradually tempered or softened are produced from nothing else but a certain thin Lamina of a vitrum or vitrified part of the Metal which by that degree of heat and the concurring action of the ambient Air is driven out and fixed on the surface of the Steel And this hints to me a very probable at least if not the true cause of the hardning and tempering of Steel which has not I think been yet given nor that I know of been so much as thought of by any And that is this that the hardness of it arises from a greater proportion of a vitrified Substance interspersed through the pores of the Steel And that the tempering or softning of it arises from the proportionate or smaller parcels of it left within those pores This will seem the more probable if we consider these Particulars First That the pure parts of Metals are of themselves very flexible and tuff that is will indure bending and hammering and yet retain their continuity Next That the Parts of all vitrified Substances as all kinds of Glass the Scoria of Metals c. are very hard and also very brittle being neither flexible nor malleable but may by hammering or beating be broken into small parts or powders Thirdly That all Metals excepting Gold and Silver which do not so much with the bare fire unless assisted by other saline Bodies do more or less vitrifie by the strength of fire that is are corroded by a saline Substance which I elsewhere shew to be the true cause of fire and are thereby as by several other Menstruums converted into Scoria And this is called calcining of them by Chimists Thus Iron and Copper by heating and quenching do turn all of them by degrees into Scoria which are evidently vitrified Substances and unite with Glass and are easily fusible and when cold very hard and very brittle Fourthly That most kind of Vitrifications or Calcinations are made by Salts uniting and incorporating with the metalline Particles Nor do I know any one calcination wherein a Saline body may not with very great probability be said to be an agent or coadjutor Fifthly That Iron is converted into Steel by means of the incorporation of certain salts with which it is kept a certain time in the fire Sixthly That any Iron may in a very little time be case hardned as the Trades-men call it by casing the iron to be hardned with clay and putting between the clay and iron a good quantity of a mixture of Vrine Soot Sea-salt and Horses hoofs all which contein great quantities of Saline bodies and then putting the case into a good strong fire and keeping it in a considerable degree of heat for a good while and afterwards heating and quenching or cooling it suddenly in cold water Seventhly That all kind of vitrify'd substances by being suddenly cool'd become very hard and brittle And thence arises the pretty Phoenomena of the Glass Drops which I have already further explained in its own place Eighthly That those metals which are not so apt to vitrifie do not acquire any hardness by quenching in water as Silver Gold c. These considerations premis'd will I suppose make way for the more easie reception of this following Explication of the Phaenomena of hardned and temper'd Steel That Steel is a substance made out of Iron by means of a certain proportionate Vitrification of several parts which are so curiously and proportionately mixt with the more tough and unalter'd parts of the Iron that when by the great heat of the fire this vitrify'd substance is melted and consequently rarify'd and thereby the pores of the Iron are more open if then by means of dipping it in cold water it be suddenly cold and the parts hardned that is stay'd in that same degree of Expansion they were in when hot the parts become very hard and brittle and that upon the same account almost as small parcels of glass quenched in water grow brittle which we have already explicated If after this the piece of Steel be held in some convenient heat till by degrees certain colours appear upon the surface of the brightned metal the very hard and brittle tone of the metal by degrees relaxes and becomes much more tough and soft namely the action of the heat does by degrees loosen the parts of the Steel that were before streached or set atilt as it were and stayed open by each other whereby they become relaxed and set at liberty whence some of the more brittle interjacent parts are thrust out and melted into a thin skin on the surface of the Steel which from no colour increases to a deep Purple and so onward by these gradations or consecutions White Yellow Orange Minium Scarlet Purple Blew Watchet c. and the parts within are more conveniently and proportionately mixt and so they gradually subside into a texture which is much better proportion'd and closer joyn'd whence that rigidnesse of parts ceases and the parts begin to acquire their former ductilness Now that 't is nothing but the vitrify'd metal that sticks upon the surface of the colour'd body is evident from this that if by any means it be scraped and rubb'd off the metal underneath it is white and clear and if it be kept longer in the fire so as to increase to a considerable thickness it may by blows be beaten off in flakes This is further confirm'd by this observable that that Iron or Steel will keep longer from rusting which is covered with this vitrify'd case Thus also Lead will by degrees be all turn'd into a litharge for that colour which covers the top being scum'd or shov'd aside appears to be nothing else but a litharge or vitrify'd Lead This is observable also in some sort on Brass Copper Silver Gold Tin but is most conspicuous in Lead all those Colours that cover the surface of the Metal being nothing else but a very thin vitrifi'd part of the heated Metal The other Instance we have is in Animal bodies as in Pearls Mother of Pearl-shels Oyster-shels and almost all other kinds of stony shels whatsoever This have I also sometimes with pleasure observ'd even in Muscles and Tendons Further if you take any glutinous substance and run it exceedingly thin upon the surface of a smooth glass or a polisht metaline body you shall
Whether the globular form of the smaller parcels of matter here upon the Earth as that of Fruits Pebbles or Flints c. which seem to have been a Liquor at first may not be caused by the heterogeneous ambient fluid For thus we see that melted Glass will be naturally formed into a round Figure so likewise any small Parcel of any fusible body if it be perfectly enclosed by the Air will be driven into a globular Form and when cold will be found a solid Ball. This is plainly enough manifested to us by their way of making shot with the drops of Lead which being a very pretty curiosity and known but to a very few and having the liberty of publishing it granted me by that Eminent Virtuoso Sir Robert Moray who brought in this Account of it to the Royal Society I have here transcribed and inserted To make small shot of different sizes Communicated by his Highness P. R. TAke Lead out of the Pig what quantity you please melt it down stir and clear it with an iron Ladle gathering together the blackish parts that swim at top like scum and when you see the colour of the clear Lead to be greenish but no sooner strew upon it Auripigmentum powdered according to the quantity of Lead about as much as will lye upon a half Crown piece will serve for eighteen or twenty pound weight of some sorts of Lead others will require more or less After the Auripigmentum is put in stir the Lead well and the Auripigmentum will flame when the flame is over take out some of the Lead in a Ladle having a lip or notch in the brim for convenient pouring out of the Lead and being well warmed amongst the melted Lead and with a stick make some single drops of Lead trickle out of the Ladle into water in a Glass which if they fall to be round and without tails there is Auripigmentum enough put in and the temper of the heat is right otherwise put in more Then lay two bars of Iron or some more proper Iron-tool made on purpose upon a Pail of water and place upon them a round Plate of Copper of the size and figure of an ordinary large Pewter or Silver Trencher the hollow whereof is to be about three inches over the bottom lower then the brims about half an inch pierced with thirty forty or more small holes the smaller the holes are the smaller the shot will be and the brim is to be thicker then the bottom to conserve the heat the better The bottom of the Trencher being some four inches distant frum the water in the Pail lay upon it some burning Coles to keep the Lead melted upon it Then with the hot Ladle take Lead off the Pot where it stands melted and pour it softly upon the burning Coles over the bottom of the Trencher and it will immediately run through the holes into the water in small round drops Thus pour on new Lead still as fast as it runs through the Trencher till all be done blowing now and then the Coles with hand-Bellows when the Lead in the Trencher cools so as to stop from running Whilst one pours on the Lead another must with another Ladle thrusted four or five inches under water in the Pail catch from time to time some of the shot as it drops down to see the size of it and whether there be any faults in it The greatest care is to keep the Lead upon the Trencher in the right degree of heat if it be too cool it will not run through the Trencher though it stand melted upon it and this is to be helped by blowing the Coals a little or pouring on new Lead that is hotter but the cooler the Lead the larger the Shot and the hotter the smaller when it is too hot the drops will crack and fly then you must stop pouring on new Lead and let it cool and so long as you observe the right temper of the heat the Lead will constantly drop into very round Shot without so much as one with a tail in many pounds When all is done take your Shot out of the Pail of water and put it in a Frying-pan over the fire to dry them which must be done warily still shaking them that they melt not and when they are dry you may separate the small from the great in Pearl Sives made of Copper or Lattin let into one another into as many sizes as you please But if you would have your Shot larger then the Trencher makes them you may do it with a Stick making them trickle out of the Ladle as hath been said If the Trencher be but toucht a very little when the Lead stops from going through it and be not too cool it will drop again but it is better not to touch it at all At the melting of the Lead take care that there be no kind of Oyl Grease or the like upon the Pots or Ladles or Trencher The Chief cause of this Globular Figure of the Shot seems to be the Auripigmentum for as soon as it is put in among the melted Lead it loses its shining brightness contracting instantly a grayish film or skin upon it when you scum it to make it clean with the Ladle So that when the Air comes at the falling drop of the melted Lead that skin constricts them every where equally but upon what account and whether this be the true cause is left to further disquisition Much after this same manner when the Air is exceeding cold through which it passes do we find the drops of Rain falling from the Clouds congealed into round Hail-stones by the freezing Ambient To which may be added this other known Experiment That if you gently let fall a drop of water upon small sand or dust you shall find as it were an artificial round stone quickly generated I cannot upon this occasion omit the mentioning of the strange kind of Grain which I have observed in a stone brought from Kettering in Northamptonshire and therefore called by Masons Kettering-Stone of which see the Description Which brings into my mind what I long since observed in the fiery Sparks that are struck out of a Steel For having a great desire to see what was left behind after the Spark was gone out I purposely struck fire over a very white piece of Paper and observing diligently where some conspicuous sparks went out I found a very little black spot no bigger then the point of a Pin which through a Microscope appeared to be a perfectly round Ball looking much like a polisht ball of Steel insomuch that I was able to see the Image of the window reflected from it I cannot here stay having done it more fully in another place to examine the particular Reasons of it but shall only hint that I imagine it to be some small parcel of the Steel which by the violence of the motion of the stroke most of which seems to be imprest upon
that it almost made me deaf for the present and much surpassed the noise of a Musket The like have I done by throwing into the fire small glass Bubbles hermetically sealed with a little drop of Water included in them Thus Water also or any other Liquor included in a convenient vessel by being warmed manifestly expands it self with a very great violence so as to break the strongest vessel if when heated it be narrowly imprisoned in it This is very manifest by the sealed Thermometers which I have by several tryals at last brought to a great certainty and tenderness for I have made some with stems above four foot long in which the expanding Liquor would so far vary as to be very neer the very top in the heat of Summer and prety neer the bottom at the coldest time of the Winter The Stems I use for them are very thick straight and even Pipes of Glass with a very small perforation and both the head and body I have made on purpose at the Glass-house of the same metal whereof the Pipes are drawn these I can easily in the flame of a Lamp urged with the blast of a pair of Bellows seal and close together so as to remain very firm close and even by this means I joyn on the body first and then fill both it and a part of the stem proportionate to the length of the stem and the warmth of the season I fill it in with the best rectified spirit of Wine highly ting'd with the lovely colour of Cocheneel which I deepen the more by pouring some drops of common spirit of Vrine which must not be too well rectified because it will be apt to make the Liquor to curdle and stick in the small perforation of the stem This Liquor I have upon tryal found the most tender of any spirituous Liquor and those are much more sensibly affected with the variations of heat and cold then other more flegmatick and ponderous Liquors and as capable of receiving a deep tincture and keeping it as any Liquor whatsoever and which makes it yet more acceptable is not subject to be frozen by any cold yet known When I have thus filled it I can very easily in the forementioned flame of a Lamp seal and joyn on the head of it Then for graduating the stem I fix that for the beginning of my division where the surface of the liquor in the stem remains when the ball is placed in common distilled water that is so cold that it just begins to freeze and shoot into flakes and that mark I fix at a convenient place of the stem to make it capable of exhibiting very many degrees of cold below that which is requisite to freeze water the rest of my divisions both above and below this which I mark with a o or nought I place according to the Degrees of Expansion or Contraction of the Liquor in proportion to the bulk it had when it indur'd the newly mention'd freezing cold And this may be very easily and accurately enough done by this following way Prepare a Cylindrical vessel of very thin plate Brass or Silver ABCD of the figure Z the Diameter AB of whose cavity let be about two inches and the depth BC the same let each end be cover'd with a flat and smooth plate of the same substance closely soder'd on and in the midst of the upper cover make a pretty large hole EF about the bigness of a fifth part of the Diameter of the other into this fasten very well with cement a straight and even Cylindrical pipe of Glass EFGH the Diameter of whose cavity let be exactly one tenth of the Diameter of the greater Cylinder Let this pipe be mark'd at GH with a Diamant so that G from E may be distant just two inches or the same height with that of the cavity of the greater Cylinder then divide the length EG exactly into 10 parts so the capacity of the hollow of each of these divisions will be 1 1000 part of the capacity of the greater Cylinder This vessel being thus prepared the way of marking and graduating the Thermometers may be very easily thus performed Fill this Cylindrical vessel with the same liquor wherewith the Thermometers are fill'd then place both it and the Thermometer you are to graduate in water that is ready to be frozen and bring the surface of the liquor in the Thermometer to the first marke or o then so proportion the liquor in the Cylindrical vessel that the surface of it may just be at the lower end of the small glass-Cylinder then very gently and gradually warm the water in which both the Thermometer and this Cylindrical vessel stand and as you perceive the ting'd liquor to rise in both stems with the point of a Diamond give several marks on the stem of the Thermometer at those places which by comparing the expansion in both Stems are found to correspond to the divisions of the cylindrical vessel and having by this means marked some few of these divisions on the Stem it will be very easie by these to mark all the rest of the Stem and accordingly to assign to every division a proper character A Thermometer thus marked and prepared will be the fittest Instrument to make a Standard of heat and cold that can be imagined For being sealed up it is not at all subject to variation or wasting nor is it liable to be changed by the varying pressure of the Air which all other kind of Thermometers that are open to the Air are liable to But to proceed This property of Expansion with Heat and Contraction with Cold is not peculiar to Liquors only but to all kind of solid Bodies also especially Metals which will more manifestly appear by this Experiment Take the Barrel of a Stopcock of Brass and let the Key which is well fitted to it be riveted into it so that it may slip and be easily turned round then heat this Cock in the fire and you will find the Key so swollen that you will not be able to turn it round in the Barrel but if it be suffered to cool again as soon as it is cold it will be as movable and as easie to be turned as before This Quality is also very observable in Lead Tin Silver Antimony Pitch Rosin Bees-wax Butter and the like all which if after they be melted you suffer gently to cool you shall find the parts of the upper Surface to subside and fall inwards losing that plumpness and smoothness it had whilst in fusion The like I have also observed in the cooling of Glass of Antimony which does very neer approach the nature of Glass But because these are all Examples taken from other materials then Glass and argue only that possibly there may be the like property also in Glass not that really there is we shall by three or four Experiments indeavour to manifest that also And the First is an Observation that is very obvious
Hypothesis is more largely explicated in the Description of Charcoal To conclude we see by this Instance how much Experiments may conduce to the regulating of Philosophical notions For if the most Acute Des Cartes had applied himself experimentally to have examined what substance it was that caused that shining of the falling Sparks struck from a Flint and a Steel he would certainly have a little altered his Hypothesis and we should have found that his Ingenious Principles would have admitted a very plausible Explication of this Phaenomenon whereas by not examining so far as he might he has set down an Explication which Experiment do's contradict But before I leave this Description I must not forget to take notice of the Globular form into which each of these is most curiously formed And this Phaenomenon as I have elsewhere more largely shewn proceeds from a propriety which belongs to all kinds of fluid Bodies more or less and is caused by the Incongruity of the Ambient and included Fluid which so acts and modulates each other that they acquire as neer as is possible a sperical or globular form which propriety and several of the Phaenomena that proceed from it I have more fully explicated in the sixth Observation One Experiment which does very much illustrate my present Explication and is in it self exceeding pretty I must not pass by And that is a way of making small Globules or Balls of Lead or Tin as small almost as these of Iron or Steel and that exceeding easily and quickly by turning the filings or chips of those Metals also into perfectly round Globules The way in short as I received it from the Learned Physitian Doctor I. G. is this Reduce the Metal you would thus shape into exceeding fine filings the finer the filings are the finer will the Balls be Stratifie these filings with the fine and well dryed powder of quick Lime in a Crucible proportioned to the quantity you intend to make When you have thus filled your Crucible by continual stratifications of the filings and powder so that as neer as may be no one of the filings may touch another place the Crucible in a gradual fire and by degrees let it be brought to a heat big enough to make all the filings that are mixt with the quick Lime to melt and no more for if the fire be too hot many of these filings will joyn and run together whereas if the heat be proportioned upon washing the Lime-dust in fair Water all those small filings of the Metal will subside to the bottom in a most curious powder consisting all of exactly round Globules which if it be very fine is very excellent to make Hour-glasses of Now though quick Lime be the powder that this direction makes choice of yet I doubt not but that there may be much more convenient ones found out one of which I have made tryal of and found very effectual and were it not for discovering by the mentioning of it another Secret which I am not free-to impart I should have here inserted it Observ. IX Of the Colours observable in Muscovy Glass and other thin Bodies MOscovy-glass or Lapis specularis is a Body that seems to have as many Curiosities in its Fabrick as any common Mineral I have met with for first It is transparent to a great thickness Next it is compounded of an infinite number of thin flakes joyned or generated one upon another so close smooth as with many hundreds of them to make one smooth and thin Plate of a transparent flexible substance which with care and diligence may be slit into pieces so exceedingly thin as to be hardly perceivable by the eye and yet even those which I have thought the thinnest I have with a good Microscope found to be made up of many other Plates yet thinner and it is probable that were our Microscopes much better we might much further discover its divisibility Nor are these flakes only regular as to the smoothness of their Surfaces but thirdly In many Plates they may be perceived to be terminated naturally with edges of the figure of a Rhomboeid This Figure is much more conspicuous in our English talk much whereof is found in the Lead Mines and is commonly called Spar and Kauck which is of the same kind of substance with the Selenitis but is seldom found in so large flakes as that is nor is it altogether so tuff but is much more clear and transparent and much more curiously shaped and yet may be cleft and flak'd like the other Selenitis But fourthly this stone has a property which in respect of the Microscope is more notable and that is that it exhibits several appearances of Colours both to the naked Eye but much more conspicuously to the Microscope for the exhibiting of which I took a piece of Muscovy-glass and splitting or cleaving it into thin Plates I found that up and down in several parts of them I could plainly perceive several white specks or flaws and others diversly coloured with all the Colours of the Rainbow and with the Microscope I could perceive that these Colours were ranged in rings that incompassed the white speck or flaw and were round or irregular according to the shape of the spot which they terminated and the position of Colours in respect of one another was the very same as in the Rainbow The consecution of those Colours from the middle of the spot outward being Blew Purple Scarlet Yellow Green Blew Purple Scarlet and so onwards sometimes half a score times repeated that is there appeared six seven eight nine or ten several coloured rings or lines each incircling the other in the same manner as I have often seen a very vivid Rainbow to have four or five several Rings of Colours that is accounting all the Gradations between Red and Blew for one But the order of the Colours in these Rings was quite contrary to the primary or innermost Rainbow and the same with those of the secondary or outermost Rainbow these coloured Lines or Irises as I may so call them were some of them much brighter then others and some of them also very much broader they being some of them ten twenty nay I believe neer a hundred times broader then others and those usually were broadish which were neerest the center or middle of the flaw And oftentimes I found that these Colours reacht to the very middle of the flaw and then there appeared in the middle a very large spot for the most part all of one colour which was very vivid and all the other Colours incompassing it gradually ascending and growing narrower towards the edges keeping the same order as in the secundary Rainbow that is if the middle were Blew the next incompassing it would be a Purple the third a Red the fourth a Yellow c. as above if the middle were a Red the next without it would be a Yellow the third a Green the fourth a Blew and so onward And
not onely into the Microscopical pores and so perfectly stoping them up but also into the pores or interstitia which may perhaps be even in the texture or Schematismâ— of that part of the Wood which through the Microscope appears most solid do thereby so aâ—gment the weight of the Wood as to make it above three times heavier then water and perhaps six times as heavie as it was when Wood. Next they thereby so lock up and â—etter the parts of the Wood that the fire cannot easily make them flie away but the action of the fire upon them is onely able to Char those parts as it were like a piece of Wood if it be clos'd very fast up in Clay and kept a good while red-hot in the fire will by the heat of the fire be charr'd and not consum'd which may perhaps also be somewhat of the cause why the petrify'd substance appear'd of a dark brown colour after it had been burnt By this intrusion of the petrifying particles this substance also becomes hard and friable for the smaller pores of the Wood being perfectly wedg'd and stuft up with those stony particles the small parts of the Wood have no places or pores into which they may slide upon bending and consequently little or no flexion or yielding at all can be caus'd in such a substance The remaining particles likewise of the Wood among the stony particles may keep them from cracking and flying when put into the fire as they are very apt to do in a Flint Nor is Wood the onely substance that may by this kind of transâ—â—tation be chang'd into stone for I my self have seen and examin'd very many kinds of substances and among very credible Authours we may meet with Histories of such Metamorphoses wrought almost on all kind of substances both Vegetable and Animal which Histories it is not my business at present either to relate or epitomise but only to set down some Observation I lately made on several kind of petrify'd Shels found about Keinsham which lies within four or five miles of Brisâ—ol which are commonly call'd Serpentine-stones Examining several of these very curiously figur'd bodies which are commonly thought to be Stones form'd by some extraordinary Plastick virtue latent in the Earth itself I took notice of these particulars First that these figured bodies or stones were of very differing substances as to hardness some of Clay some Marle some soft Stone almost of the hardness of those soft stones which Masons call Fire-stone others as hard as Portland stone others as hard as Marble and some as hard a a Flint or Crystal Next they were of very differing substances as to transparency and colour some white some almost black some brown some Metalline or like Marchasites some transparent like white Marble others like flaw'd Crystal some gray some of divers colours some radiated like these long petrify'd drops which are commonly found at the Peak and in other subterraneous caverns which have a kind of pith in the middle Thirdly that they were very different as to the manner of their outward figuration for some of them seem'd to have been the substance that had fill'd the Shell of some kind of Shel-fish others to have been the substance that had contain'd or enwrapp'd one of those Shels on both which the perfect impression either of the inside or outside of such Shells seem'd to be left but for the most part those impressions seem'd to be made by an imperfect or broken Shell the great end or mouth of the Shell being always wanting and oftentimes the little end and sometimes half and in some there were impressions just as if there had been holes broken in the figurating imprinting or moulding Shell some of them seem'd to be made by such a Shell very much brused or flaw'd insomuch that one would verily have thought that very figur'd stone had been broken or brused whilst a gelly as 't were and so hardned but within in the grain of the stone there appear'd not the least sign of any such bruse or breaking but onely on the very uttermost superficies Fourthly they were very different as to their outward covering some having the perfect Shell both in figure colour and substance sticking on upon its surface and adhering to it but might very easily be separated from it and like other common Cockle or Scolop-shels which some of them most accurately resembled were very dissoluble in common Vinegar others of them especially those Serpentine or Helical stones were cover'd or retained the shining or Pearl-colour'd substance of the inside of a Shel which substance on some parts of them was exceeding thin and might very easily be rubbed off on other parts it was pretty thick and retained a white coat or flaky substance on the top just like the outsides of such Shells some of them had very large pieces of the Shell very plainly sticking on to them which were easily to be broken or flaked off by degrees they likewise some of them retain'd all along the surface of them very pretty kind of sutures such as are observ'd in the skulls of several kinds of living creatures which sutures were most curiously shap'd in the manner of leaves and every one of them in the same Shell exactly one like another which I was able to discover plainly enough with my naked eye but more perfectly and distinctly with my Microscope all these sutures by breaking some of these stones I found to be the termini or boundings of certain diaphragms or partitions which seem'd to divide the cavity of the Shell into a multitude of very proportionate and regular cells or caverns these Diaphragms in many of them I found very perfect and compleat of a very distinct substance from that which fill'd the cavities and exactly of the same kind with that which covered the outside being for the most part whitish or mother-of-pearl colour'd As for the cavities between those Diaphragms I found some of them fill'd with Marle and others with several kinds of stones others for the most part hollow onely the whole cavity was usually covered over with a kind of tartareous petrify'd substance which stuck about the sides and was there shot into very curious regular Figures just as Tartar or other dissolv'd Salts are observ'd to stick and crystallize about the sides of the containing Vessels or like those little Diamants which I before observed to have covered the vaulted cavity of a Flint others had these cavities all lin'd with a kind of metalline or marchasite-like substance which with a Microscope I could as plainly see most curiously and regularly figured as I had done those in a Flint From all which and several other particulars which I observ'd I cannot but think that all these and most other kinds of stony bodies which are found thus strangely figured do owe their formation and figuration not to any kind of Plastick virtue inherent in the earth but to the Shells of certain Shel-fishes which either by
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 Phaenomena by supposing the pulse onely to be communicated through the transparent body To this I answer that that Hypothesis which the industrious Moreanus 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 Phaenomena 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 Phaenomena 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 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 28 part of an Inch long I found by numbring 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 containe 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 Vitae 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 in 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 Phaenomena 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 wheresover 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 evidenâ— 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 divalsion 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