CHAP. I.

I have, in a former Tract, endea­vour'd (and, as I am told in Print, and otherwise, not altogether unsuccessfully) to make it proba­ble, that divers, if not most, of the real Virtues (for many fabulous Ones have been ascrib'd to them) of Gems or precious Stones, may in great part proceed from the Qualities of Me­talline and Mineral Substances, That, whilst the Matter was either fluid or soft, were (more or less plentiful­ly) incorporated with the stony Mat­ter, [Page 2] which hardned afterwards into a Gem. The same Phoenomena and Reflections, that led me to the Opi­nion newly recited, induced me to think it also very probable, that di­vers Boles, Clayes, and other Earths, and, much more, that several Minerals; which, tho' not looked upon as Me­talline Oars, and several Stones or sto­ny Substances, that, by reason of their Bigness or Opacity, or perhaps un­pleasant Colours, have been judged un­worthy to be numbred among Gems or precious Stones, may yet be indow­ed with considerable Medical Virtues; & perhaps with greater than the finer Gems themselves, because in these despised Stones and Minerals, there is often found a greater store of Me­tallick and Mineral parts, which while they were in solutis Princi­piis, as Chymists speak, might with ease plentifully insinuate themselves into these more open Bodies, where being setled they were not lockt up so fast and strongly, as in the noble [...] Gems; such as Diamonds, Rubies▪ [Page 3] Saphirs, &c. which are of so Com­pact, and as 'twere Glass-like, a Na­ture, that divers Corrosive Liquors, and Aqua Fortis it self, are unable to penetrate and dissolve them; tho', as hereafter will appear, these infe­riour Medical Stones, and other Mi­nerals, may be opened by the like Menstruums.

Upon these Grounds, I thought it might be a thing of use to Physici­ans, as well as to divers Mineralists and Mine-workers; if I imparted to them a Way of Exploring many Fos­sils, that I do not remember I had met with, either among Physicians or Chymists: And tho' this Way of Exploration pretends not to disco­ver directly more than one Quality of the Body examined by it; yet that Quality, being its specifick Gra­vity, is so radical and considerable a one, that it may lead a Sagacious Enquirer further than at first sight one would think.

I considered then, that the most pure and homogeneous kind of Stones [Page 4] we know of, and that seems the freest from all adventitious Mixtures, and even Tinctures TR's▪ is Rock-Chrystal: And therefore I pitched upon This, as the Standard I would imploy, to make Estimates of the greater or lesser re­cess from Simplicity or Homogeneity of the Stones, or other Stone-like Substances, whose specifick Gravity I should examine.

We took then some Pieces of na­tive Chrystal, clear and colourless, and having carefully weighed them first in the Air, and then in Water, we found, by Computation, that pure Chrystal was to clear Water of the same Bulk, as Two and an half, or thereabouts, are to One: So that, to clear the Matter by an Instance, if we suppose an hollow Cube, of Brass or other Metal, to be filled as carefully as may be, (for the upper Surface will scarce be exactly Level) with ℥j. of Water, and if afterwards the Cavity of the empty'd Vessel be ex­actly filled with a Cubical piece of Rock Chrystal; this Stone will [Page 5] weigh ℥ij and about an half. Some of my Tryals indeed, made with ten­der Ballances, represented the Pro­portion of these two Bodies, with some petty Variation. But besides, that 'tis not improbable, that diffe­ring pieces of Rock Chrystal it self, tho' of equal Bulk, may not be pre­cisely equal in Ponderosity; besides this, I say, the Variation I found from the newly assigned Proportion was so small, that having just intimated, that for the most part it rather sa­voured a little the specifick Gravity of the Chrystal, than fell short of it; we may neglect it without any pre­judice, worth taking notice of, to the Use that is to be made of this Pro­portion in this Paper. And for as much as there may be some Scruple, tho' groundless, made about the Origin and Nature of Chrystal: I shall add, by way of Confirmation of what has been delivered, that I procured some strong Icicles, that had been fasten'd to Vaults, &c. as Bo­dies that would be acknowledged to [Page 6] be true Stones, and yet to have been in a Liquid Form; and having Hy­drostatically examined these Concre­tions, the specifick Gravity, tho' not exactly the same in all, appeared to be little differing from that of Chry­stal; the solid Body exceeding the Weight of the fluid water, it Was Weigh'd in, about two times and an half, (a little more or less.)

Use I.To apply this Fundamental Obser­vation to the Uses designed in it, when I had a mind to make a proba­ble Discovery, (for by this Way I pre­tend to no more) whether in a Stone, or Stone-like Body propounded, the merely stony Matter were more or less commixt with some adventiti­ous Substance of a Metalline Na­ture, or that of some other Mineral more ponderous than Chrystal, I care­fully weighed it: First in the Air, and then in the Water, according to the Method formerly declared, and if by Virtue of its specifick Gravity, its Proportion to Water of the same Bulk, exceeded the Proportion of five [Page 7] to two (which to avoid Fractions, may be commodiously substituted to that often already mentioned of 2 1/ [...] to one) I concluded it probable, that the Concretion had in it a Portion of adventitious Matter, heavier in Specie than Chrystal or mere Stone, by how much more or less the solid Body exceeded the Weight of Water equal to it in Bulk, by so much grea­ter or lesser a Portion of Heteroge­neous Matter was guest to be com­mixed with the stony in the pro­pounded Concrete. This may be illustrated, as well as proved, by the Examples that should presently fol­low, but that it will be fit, before I descend to Particulars, to premise a Paper that concerns the whole De­sign of this Tract.

CHAP. II.

THO' the Way of weighing So­lids in Water hath been deli­vered [Page 8] by the ingenious Marinus Ghe­taldus, and, out of him, by some few other Authors, and tho' therefore I might excusably dispense my self from delivering it distinctly: Yet since their Books are scarce, and the knowledge of this Way is almost every where supposed in these Pa­pers, I hold it very fit, that it should once be proposed in this Tract, not only for that Reason, but for Two others. One, that a dextrous way of finding out the Weight of Bodies in Liquors, may be of far more use than Men seem to be yet aware of, being capable of being made, by a little Variation and Improvement, of good use to Naturalists, and even to Chymists. And the Other, that per­haps you will find cause to think, that Experience and Reflections on it may have furnisht me with some few Expedients and Cautions for the bet­ter Practice of this Art, and for the avoiding of some Errors, that may be very easily, and perhaps have been, run into, for want of the Cautions here given.

CHAP. III.

ANd now having premised these Remarks, and thereby made way for the clearer Understanding of the subsequent part of this Paper; we shall proceed to the Examples, that this not unnecessary Digression has diverted us from propounding.

[Page 22]There is a deeply Red and Opa­cous Mineral, that commonly passes in the Shops under the Name of La­pis Haematites, tho' it seems to have more Affinity to that which divers Authors call Schystos. But whatever be the most proper Name that be­longs to it, it is an hard Fossile, which, tho' little used by our English Physici­ans, is in several Places abroad in great Request; & that not without cause, as far as I can judge, by what I yet know of it; and especially, for that Somni­ferous Quality, that may be observed in some of its Preparations. But 'tis not here, tho' 'tis elsewhere, my Pur­pose to deliver its Medicinal Virtues; but only to examine, whether, accor­ding to our Method, it ought to be concluded to abound with Metallick Particles, (perhaps but Embryonated,) to whose Intermixture some of its Virtues may probably be ascrib'd. Therefore, in a very good Ballance, having weigh'd a piece of English Haematites, that chanced to amount to about ℥iij ʒij [...]/4, First, in the Air, [Page 23] and then in Water; we found its Pro­portion to this Liquor, as 4 15/100 to 1. At which Ponderosity, if I had not formerly made the like Experiments, I should have been surprized; as you probably will be, when you consider, that this Metalline Stone did not very much want of almost twice the Weight of a mere Stone of the same Bulk. This great Weight much con­firmed me in the Conjecture I had made; that in this Lump was con­tain'd a good deal of Metalline Sub­stance. And this induced me (to add that upon the by) to examine my Guess, by subliming it, when finely powdered, and diligently mixt with an equal, or double, Weight of Salar­monia [...]. For then having tasted, with the tip of my Tongue, of this Saffron-coloured Sublimate; I found it; as I expected, very Astringent or Styp­tick, as divers Preparations of Mars are wont to be; and, for further Proof, having put less than a Grain of it in­to a spoonful or two of good Infu­sion of Galls; there was immediate­ly [Page 24] produced a Black, and as it 'twere Inky, Mixture.

Lapis Lazuli is sometimes made use of by Europaean Physicians, but more frequently by Arabian and o­ther Eastern Ones, for divers purposes, but especially to make Evacuations by Vomit. This Emetick Faculty seem­ed, likely enough, to belong to it up­on the Score of a Metalline Ingre­dient; and accordingly, having ex­amined Hydrostatically, a piece that was judged moderately rich, we found the Proportion of it to an e­qual Bulk of Water, to be as 3. to 1. which argues That, notwithstanding its briskness in Operation, it con­tained a much lesser Proportion of Metalline Substance, than Lapis Hae­matites, or divers less Operative Mi­nerals.

Observati­on about the Load­stone, as 'tis a Mi­neral.I elsewhere shew, that the Load­stone may be applyed to Medicinal Uses, and that it emits Effluvia, that are not Magnetical, and may have sensible Operations upon the Body of Man. On which account, it was not [Page 25] improper to examine it Hydrostati­cally; by which means I found, that the Weight of a Lump of Loadstone, that I judged to be either English or Norwegian; was in Proportion to Wa­ter of the same Magnitude, as 4 91/10 [...] to 1. But of the specifick Gravities of Loadstones, much more may be met with in another Paper.

Lapis Calaminaris is often enough used in Physick, especially by Chy­mists, to dry; and to imbibe Acidities. For which Uses, I prefer it before di­vers more famous Drugs: But, tho' 'tis wont to be imployed, only as an ex­ternal Remedy; yet some things, that I found in some uncommon Chy­mical Preparations of it, made me think, it may deserve to be further examined and tryed. A famous and not unlearned Empyrick, to whom I willingly communicated some Pro­cesses, that he desired of me; when I asked him about a Medicine, whose Success brought him a great number of Patients, for griping Fluxes, and some Dysenterical ones; candidly [Page 26] discovered his Medicine to me, and solemnly assured me, it was nothing, but pure and well-ground Lapis Cala­minaris, seasonably given in a just Dose; as in a fitter place I have more fully declared. This made it obvious for for me to conjecture, that Lapis Cala­minaris participates of a Metallick Nature, as may be argued from its Operation upon Copper, which is thereby turned into Brass. Wherefore weighing a piece of this Fossile, first in Air, and then in Water, it appeared to be to this Liquor as 4 169/100 to 1.

If I had not among other Papers lost Some, wherein I had Registred a good Number of Tryals of this kind made upon differing Fossiles; 'twould be easie for me to add to the four already recited, others mani­festly conducing to the same Purpose. But presuming, that those already delivered may at present suffice; I shall now subjoyn a few Observati­ons, whereof the first may become the Candor and Impartiality of a Lover of Truth, and the rest inti­mate [Page 27] some further Uses of the Hy­drostatical Way of exploring hard and ponderous Concretions, hitherto treated of.

I must not therefore forbear to ad­monish you, that, tho' when an hard Fossile propounded, is found to be much heavier than Chrystal of the same Bulk; 'tis a very probable To­ken, that in the Solid Concretion, there is a notable Portion, greater or lesser, of some Metalline or other ponderous Mineral Body, whence its good or evil Qualities, in reference to human Bodies, may probably be deduced; Yet, this hinders not, but that 'tis very possible, for a Fossile to be endowed with Medicinal Vir­tues, or to have noxious Qualities, on the account of a Portion of ex­traneous Matter; tho' its specifick Gravity doth but little exceed that of Chrystal, or the advantage seem but inconsiderable. For, (to pass by o­ther Reflections) a very small Pro­portion of Adventitious, Metalline, or Mineral, Substance, if it be of an [Page 28] Operative Nature, may, in some Cases, suffice, to diffuse its self through the rest of the Mass, and impregnate it with active Qualities. Which may be partly Illustrated, and partly Proved, by some Experiments that will be hereafter met with, in one of the Chapters.

CHAP. IV.

Use II.TO hint somewhat about the fur­ther Utility of our Hydrostatical Way of Inquiry; I shall take notice in the first place, that it may assist us to guess, with probability, whether a Mineral Body propounded, as likely to be a Stone, or of a stony Nature, be so indeed. Thus Coral, for instance, is by some thought to be a Plant, by others a Lytho-dendron, but, by the greater Number, 'tis reckoned a­mong Precious Stones. In this Dis­sent of Opinions, the specifick Gra­vity may be of considerable Use. [Page 29] Wherefore, we thought fit to weigh a piece of choice and well colour­ed red Coral; first, in the Air, and then in the Water, and found its Proportion to the Weight of as much of that Liquor, to be as 2 68/100 to 1. So that its specifick Gravity much favours their Opinion, who take it to be a Stone, since it not only e­quals that of Chrystal, but some­what exceeds it.

There are Some, that will have Pearls, because of their Hardness, and their being treated of by Jewelers, and others that write of Gems, to be of a stony Nature. Wherefore I thought fit examine their Pondero­sity also. But not having now with me any Tryal of that kind; I shall sub­stitute One that I made upon a mon­strous Pearl, that was presented me by a Person that took it out of the Oyster. I call it Monstrous, because tho' it be well enough coloured, yet its Shape is irregular, and its Bigness extraordinary; as is also its Weight, amounting to full 206 Grains. This [Page 30] being weigh'd in Water, its Propor­tion in Gravity to an equal Bulk of the Liquor was found to be as 2 [...]1/ [...]00 to 1. So that its specifick Weight was much about the same, with that of Chrystal.

There are Many, that take the Stones formed in Mens Bladders, for as true and genuine Stones, as Those that Nature forms in the greater World; and speak much, and some­times not without ground, of the great Hardness of divers of them. But, tho' I deny not, that, in a laxer Sense, they may well enough pass for Stones; yet I should rather call them Animal Stones, than simply Stones; this Name having been constantly and generally used, to signifie Mineral or Fossile Stones: which, by our Way of Explora­tion, may be easily distinguished from human Calculus's, and other like hard Concretions, found in the Bodies of some Animals. For, having examined a good Number of these Stones, I found, that not only the Chymical Analyses, I made of them, of which [Page 31] I elsewhere give an Account, mani­fested them, how hard soever they were, to be Concretions belonging to the Animal Kingdom, not the Mi­neral: But, by an Hydrostatical Exa­men of divers of them, I found them to differ much, in specifick Gravity, from true Fossile Stones. Of this you will, in its proper place, meet with several Instances; so that it may here suffice to mention Two, that now chance to come to hand. Namely, that a Calculus humanus weighing a­bove ʒvjss was found to be in Propor­tion to an equal Bulk of Water, as 1 76/100 to 1. And another, that weighed ʒiv and above an half, in the Air, being also weighed in Wa­ter, appeared to be to this Liquor, as 1 69/100 to 1.

I mention these Stones as belonging to the Materia Medica, tho' they are lookt upon rather as Diseases, of which, indeed, they are very sad Pro­ductions, because a famous and ex­perienced Physician, that Practised long in the East-Indies, and had bet­ter [Page 32] Opportunity than almost any Eu­ropean had before him, to try the Virtues of Bezoar, does either equal or prefer the Calculi, we are speaking of, even to Oriental Bezoar.

And to shew, that Men are not the only Animals, wherein Stone-like Concretions differ in specifick Gra­vity, (and so may be distinguished, by that difference,) from Chrystal and such like true Stones; we shall sub­joyn Two or Three Experiments, made upon choice Bezoar Stones, not exceeding a middle Size, such being the likeliest not to be adulterated. The first of these weighing in the Air ʒiij, and odd Grains, was found to be in Proportion to Water of the same Bulk, as 1 47/100 to 1. Another weighing somewhat less than ʒiij, was to the Weight of an equal Bulk of Water, as 1 53/100 to 1. I might add divers other Instances of the like Import; and tho I think them not necessary, yet I shall subjoyn One more, because 'tis afforded by a Be­zoar stone, taken out of another of [Page 33] the same kind: This Kernel-stone, if I may so call it, being Weighed in the Air wanted Nine Grains of ʒiij, and its Proportion to Water of the same Magnitude, was found to be as that of 1 55/100 to 1. In all which In­stances, we may observe, that these Animal Stones not amounting to twice the Weight of Water equal to them in Bulk, have less of specifick Gravity, by above a Fifth part, than a true Fossile Stone (such as Chrystal) is wont to be endowed with.

CHAP. V.

THE Use lately proposed of our Hydrostatical Way of Ex­ploration, suggests to me Another, Use III. which may be deduced from it, as a kind of Corollary.

This comprehends two, somewhat differing, Ways of applying the Ob­servations, we have lately mentioned. For first, we may by the Hydrosta­ticks [Page 34] be assisted to discover, with Probability, the resemblance, or the difference that may be between Bo­dies of the same Denomination, so that some subordinate Species of them, may perhaps be distinguished, as well as several Individuals of the same, or lowermost, Species. Since, for Instance, we have found a nota­ble difference between the specifick Weights of several Loadstones, that were dug up in several Countries or Mines; if greater Number and Va­riety of Experiments, of this kind were made, we should possibly find, that, Caeteris paribus, the Loadstones of one Country, or of one Mine, are considerably heavier than Those of another; as, if I mistake not, I usu­ally observed, the Norwegian and the English Loadstones to be heavier in Specie, than Those that are said to come out of a warmer Region, Italy; whose Island of Elba abounds with Mines, whereof I saw one intire Mass, that I judged to weigh a great many hundred of Pounds. And this difference [Page 35] of Weight between Fossiles of the same kind, when 'tis considerable, may be of good use to help us to di­stinguish between the Stones of the same lowest Species, that are pro­per to differing Countries or Mines▪ But, in Case the unequal Weight proceeds, as it often does, from an Adventitious Matter, that insinuated it self into the more genuine Matter of the Fossile, whilst 'twas Fluid or Soft, it may much assist us to guess at the greater or lesser Purity of Ho­mogeneousness of the Fossile propo­sed; which Discovery may, on di­vers occasions, be of no small use to the Physician, the Jeweller, or the Naturalist.

CHAP. VI.

BUT the Second thing compri­zed in our Corlolary, Use IV. may in divers Cases be of much greater Uti­lity and Importance, as being very [Page 36] proper to help us to discern genuine Stones, whether Animal or Mineral, from counterfeit Ones; which too often pass for true, to the great pre­judice of Physicians and Patients, and the great Loss of Lapidarie's, and their Customers. For as there are few Qua­lities appertaining to ponderable Bo­dies here below, that are so radi­cated, (if I may so speak) as their Ponderosity is. So there is scarce any Quality, wherein 'tis so difficult for Impostors, to make a notable Al­teration unperceivedly, as the speci­fick Gravity. I said, for Impostors because, tho' in several Cases, 'tis not so very difficult, to alter the speci­fick Weight belonging to this, or that, kind of Bodies; yet in those ve­ry Cases, it may be exceeding difficult, and perhaps impractible, to make a considerable Change in tha [...] Quality, but by such Additions, o [...] Operations, as will make a sensible Change in some other Qualities too and thereby expose the Fallacy to b [...] discovered. And this will especiall [...] [Page 37] prove difficult in many Cases to vul­gar Cheats, and Counterfeiters, or Adulterators of Gems, and other va­luable Minerals; because the little knowledge they have of the Nume­rousness, and Variety, of Natural and Artificial Productions, confines them to a small Number and Diversity of Means, to accomplish their fradulent Designs. And whilst they are in­tent, but upon counterfeiting the more obvious Qualities of things; and perhaps of eluding the known and vulgar Tryals Men are wont to acquiesce in; they are not like to take Care to maintain the specifick Gra­vity, and secure their adulterated Wares, against an Hydrostatical Way of Examen, which, probably, they never so much as heard of. By this means, several Perls, for Instance, may be discovered to be Counter­terfeit, without, in the least, injuring them. And I remember, That some factitious Corals, that, for Divertise­ment, I made, to shew what might be done in that kind; were, notwith­standing [Page 38] their fine Colour, Shape, and Glossiness, easily discoverable, by their having a specifick Weight manifestly exceeding That, which be­longs to natural Corals.

Before I knew better Ways, I have sometimes, for Recreation, by the help of Minium made Pastes, or factitious Gems, which, tho' transparent, and finely enough coloured, yet, because they contained some vitrified Lead, added to the other Ingredients to pro­mote the Fusion, were liable to be de­tected by an easie Hydrostatical Tryal of their Ponderosity. I have likewise seen a fair Bezoar Stone, that so re­sembled a genuine Stone, That a great Price was set upon it. But be­ing brought me to be judged of, I made little doubt of its being Coun­terfeit, by reason of its appearing to me as heavy as a Mineral Stone of that Bulk; tho' the Possessor being loth to expose it to an uncommon Tryal, I could not so cogently evince, that I had a clear Reason to disadvise the purchase of it.

CHAP. VII.

AFter these Instances, (which are not the only, Use V. that might be al­ledged of this kind) the affinity of the Subjects invites me to take notice of another Use, or, at least, a Varia­tion of the former, which may be made of our Hydrostatical Way of examining Solids. For it may, on di­vers occasions, assist us, to make pro­bable Estimates of the Genuineness, or the degree of Purity of several Bo­dies, that are, or may, usefully be imployed in Physick; tho' they be not Stones or Minerals, provided they be heavy enough to sink in Water. For when we have once found the specifick Gravity of a Concretion of this sort, that we know to be Ge­nuine, and well-conditioned in its kind; this degree of Ponderousness may serve us for a kind of Standard, [Page 40] whereby to judge of others, of the same Denomination, or that are said to be of a like Nature.

To illustrate a Remark, that has no more of Difficulty in it than This, fewer Instances will suffice, (if any be necessary) than you will meet with in the following Part of this Tract, wherein they will opportune­ly occur. And therefore, instead of setting them down in this place, I choose to give you an Advertisement, that would surprize you, if I had not formerly hinted somewhat, applia­ble to the same purpose, by no great Variation. For that which I am a­bout to observe to you, is, That, I think, there should be made a great difference between the Estimate, that Men make of some Stones, to which the Shops give the Name of Gems, according as the Estimate is to be made by Jewellers and Goldsmiths, or by Physicians and Chymists. For the Tradesmen, who usually aim but at the Beauty and Lustre of the Gems they would Sell, may justly esteem [Page 41] those Caeteris paribus the best, that are in Specie the lightest, because such are generally more uniform as to Sense, and more Transparent; and also, receive their Colour from Pig­ments of finer Parts. But, on the con­trary, those, that in Gems seek main­ly, if not only, for the Medicinal Vir­tues; may justly value Those most, that are most Ponderous: as having more plentiful Portions of the Me­tallick, or Mineral, Substances, whence the greatest part of their Virtues is, as has been formerly no­ted, in Probability, to be derived. And this difference in specifick Weight, in Stones that have the same Name given them, I sometimes found to be far greater, than one that has not try'd it would imagine, as may ap­pear by some Instances, applicable to this Argument, that will hereafter be met with. But yet, I would not hence infer, that even such Stones, whether transparent or not, as ap­pear fine, and are but light in their kind, must be devoid of Particles, [Page 42] whether Metalline, or of kin to them, whence they may be endowed with considerable Medicinal Virtues. For there are Mineral Pigments of so sub­tle a Nature, that so small a Quantity as will scarce make them sensibly heavier than Gems that are less, or perhaps not at all coloured, may be diffused through the whole Matter; and, at least, impregnate every sensible part of it: This I shall Illustrate by the following Experiment, devised for that purpose.

Five Grains of powdered Zaphora, being mixed with ℥j ʒ ss of finely powdered Venice Glass, and kept a full hour in Fusion in a Furnace, that gives an exceeding violent Fire, af­forded a transparent Mass, that was throughout of a fine blew Colour, and that deep enough; so that one part of the Pigment sufficed to tinge, by Fusion, above an hundred parts of the Glass: And when for Curiosity, we made the Proportion of the Za­phora a little greater, taking Eight Grains of the Pigment to ℥j of Glass, [Page 43] that is, One to sixty; the Mixture ha­ving been kept for the like time in strong Fusion, the Mass was so deeply coloured, that the Proportion of the Tinging stuffe to the rest of the Wa­ter, appeared too great to make a handsome Gem.

And further to manifest, that a Quantity of Metalline Matter, tho' it be but very small, may suffice to give a Tincture, and so to impart a Virtue to a Glassy Body, and even to Gems; I shall add an Experiment, that perhaps you will think somewhat strange. I had long conjectur'd, that there was in Granats, especially in some that were deeply coloured, pret­ty store of Metalline Corpuscles of a Martial Nature, and that those Cor­puscles are more than sufficient for the Granate it self, into whose Composi­tion they enter, tho' not visibly, be­cause of their extream Minuteness. Up­on this supposition, I took a Bohemian, or rather German, Granate, (for I never saw any Bohemian so large) that I had kept by me for a Rarity, because [Page 44] of its Bigness and deep Colour, tho it was not a fine Stone to look on, notwithstanding its being transpa­rent in those Edges that were thin. This being reduced to very fine Pow­der (but not in an Iron Mortar, lest should take somthing from the Metal) we exactly mixt Eight Grains with an Ounce of finely pulverized Chrystal­line Glass; afterwards the Mixture was kept two hours in a Furnace, that gives a stronger Fire than ordinary VVind-Furnaces, by which means we obtained, as I expected, a pretty uni­form Mass tinged of a sufficiently green Colour, such as prepared Iron, or Steel, gives to pure Glass.

CHAP. VIII.

WHat has been hitherto deli­vered, may serve to shew, in some measure, the Uses of our Hydrostatical Way of examining Drugs, upon a Supposition that they are Solid, and neither very minute, nor too light to sink in Water. But I must not forbear to confess, and even [Page 45] give Notice, that there are many Simples, and other ponderable Sub­stances, that may, upon good Grounds, be said to belong to the Materia Me­dica; which yet want One, or More, of the newly expressed Conditions. Wherefore I must not conceal, that there are Three things, which, tho' not necessary to the Understanding of the Usefulness of the foregoing Part of this Discourse; may, if they can be performed, much conduce to Facilitate (for I dare not say, to Com­pleat) the Hydrostatical Way of exa­mining Bodies, heavier in Specie than Water. And therefore, tho' I con­fess it no easie Task to surmount the Difficulties to be met with in this Attempt; yet I shall endeavour to lessen them as much as I can, by offer­ing to you the Expedients, that I was wont formerly to make use of in the Three Cases, I am about to mention: Namely, First, When the Body to be examined was Liquid, and conse­quently, I could not be immediately taken hold of by an Horse-hair, or [Page 46] any other slender String. Secondly, When the Body proposed was either in the Form of Powder, or consisted of Fragments that were so small, that it 'twas not possible, or, at least, not fit, to fasten each of them to an Hair; and suspend it after the manner of a Body of a greater Bulk. And, Thirdly, When the Solid to be Hy­drostatically examined, though great enough in Bulk to be tyed about, was dissoluble in Water; and consequently unfit to be weighed in that Medi­um: Since therein its Gravity must continually decrease, whilst the Ope­ration was performing.

As to the First of the Three Diffi­culties; lately mentioned, I suppose, I need not solicitously premise, that the Liquid Substance, to be Hydro­statically examin'd, ought to be heavier in Specie, than the Water, or other Fluid, 'tis to be weighed in; and of such a Nature, as not to be apt (at least, speedily) to mingle it self with it: since, otherwise, the pro­posed Liquor will either emerge in [Page 47] that it should be weighed in, or else be confounded with it, and so re­tain no distinct Mass, or Gravity.

Supposing then, that the Liquor, to be examined, has belonging to it the Two newly recited Conditions, we made use of this Expedient to explore its specifick Weight. We took a small Jar, or wide-mouthed Glass capable of containing an Ounce or two of common Water, and weigh­ing in the Air about, Three or four Drams (more or less, as occasion re­quires.) This Glass, which▪ for Bre­vities sake, we are wont to call Hy­drostatical, or else Glass-Bucket; we weigh very carefully once for all, first in the Air, and then in the Wa­ter, and by the difference of the Weights we find, according to the known Hydrostatical Method, a Weight equivalent to That of the Substance of the Glass in Water is so that such a Weight being put into the opposite Scale of the Ballance, the Vessel hanging under the Sur­ [...]ace of the Water, may be considered [Page 48] as having no Weight at all, that is, no Praeponderancy. And con­sequently, the Weight of a Body contained in this Bucket may be looked upon, as That of the Body it self in Water, without being increa­sed by that of the Vessel; so that, in our Instance, the Bucket makes a Mass of Quick-silver, tho' Fluid, as ponderable as if 'twere coagulated into a Solid Body.

The Glass-Bucket being thus pro­vided once for all, we put the propo­sed Mercury into it, and weigh them together in the Air; whence dedu­cting the already known Weight of the Vessel it self in the Air, the Re­sidue gives the Weight of the Quick-silver alone in the Air. This done, by the help of an Horse-hair, we tye the Bucket to one of the Scales, (or to either end of the Beam,) and letting it, with the Quick-silver in it, slowly sink into a Glass, or other Vessel, competently full of fair Water, and hang so, that the Bucket may not any where touch, [Page 49] either the bottom, or the sides of the larger Vessel; we reduce by Weights, put into the opposite Scale, and ad­ded to the formerly mentioned Coun­terpoise of the Bucket in the Water, the Ballance to an exact Aequilibrium, without raising the Bucket quite to the Surface of the Water; this new­ly obtained Weight, of the immerst Quick-silver, being deducted from its Weight in the Air, 'tis easie, by the known Hydrostatical Method, to obtain the Proportion in Gravity, be­tween the given Mercury, and an equal Bulk of Water.

To expedite this Operation, it may be convenient to have in rea­diness (as I was wont to do,) a couple of Weights, of Lead, or Tin; the greater exactly equal to the Weight of the Glass-Bucket in the Air, and the other equal to the Weight of the same Bucket in Water. For, by keep­ing these two Weights constantly in readiness, One has at hand a Coun­terpoise of the Vessel, in which soe­ver of the two Medium's 'tis employ'd [Page 50] in; which saves them, that have fre­quent occasion to use the Ballance, much of the time that must other­wise be spent to adjust it.

This Advertisement being premi­sed, the lately propounded Operation will be best understood by an Exam­ple; we took a small Glass-Jar capa­ble of holding about ℥ss. of Water, and put it into one Scale of a ten­der Ballance; whose other Scale we furnisht with a Counterpoise, or Weight, equal to the Glass. Into this little Vessel, we then put ℥ 1, that is, Four hundred and eighty Grains of Mercury (affirm'd to be Spanish, which is counted the richest) and the Glass with this Mercury in it was, by an Horse-hair, made to hang from one of the Scales, into a deep Glass Vessel of Water. Whilst it wa [...] in that state, there was in the op­posite Scale a Counterpoise to the Glass it self in the Water, so tha [...] the Drams and Grains, that 'twas re­quisite to add, gave us the Weigh [...] of the Quick-silver only, the Weigh [...] [Page 51] of the Glass, being already accoun­ted for. But Care was first taken, that the open-mouth'd Vessel should be every where environed with Wa­ter, and diligently freed from adhe­rent Bubbles; and that a piece of Horse-hair should be added to the Counterpoise, to compensate that part of the String or Hair tyed a­bout the Bucket, that was in the Air, intercepted between the Scale, it was fastened to, and the Surface of the Water. By this means, we found the Weight of the Quick-silver in that Liquor, to amount to 446 Grains, which being substracted from the Weight of the Quick-silver in the Air, the difference was 34 Grains, by which the greater Num­ber being divided, the Quotient was 14 and about 1/1 [...]. So that the Mer­cury, imploy'd in this Operation, ap­peared to be in Gravity to Water of the same Bulk, as 14 11/ [...] to 1. I said, the Mercury imployed in this Opera­tion, because, in former Tryals, I scarce found common Quick-silver, [Page 52] that was bought in Shops, to weigh full Fourteen times, and sometimes scarce 13 and ½ as much as a Bulk of Water equal to it; whether the Ponderousness of our last used Mer­cury proceeded from hence; that, as some Chymists extol Spanish Mercu­ry, as participating more than o­thers of a Golden Nature, (which O­pinion, a Tryal, that I purposely made of That imploy'd about the late Experiment, did not disfavour;) So, there was in this of Ours some­thing of unfixt Gold, that some­what increased its Weight; I leave to further Enquiry.

If you can command, as I can­not, the Learned Ghetaldus's Archi­medes Promo [...]us: Since, as I am in­formed, He there sets down the in­tensive Weight of Quick-silver Hy­drostatically found; it may be worth your while to consult that scarce Book, and compare the things you may meet with there, relating to Quick-silver, with what I have now delivered. To which I shall add, [Page 53] That this I may here give you No­tice of in general; That, having on Chymical and other Accounts, had more occasion than most Men, to make Tryals of this sort, I did not find all running Mercuries, tho' they did not appear adulterated, to be pre­cisely of the same Weight: Nay, even destilled Mercuries, if once combin'd with Metalline Bodies, and particularly, if they were animated, and drawn from fine Gold; I found to differ more from common Mercu­ries sold in Shops, than These did from one another; and even between common Mercuries, notwithstand­ing their having been Destilled, we found a notable Disparity. But to inlarge on this Subject, were impro­per in this Place, where I mentioned the Weight of Mercury: But to give so clear (tho' but single) an Instance of the Way of measuring the Weight of ponderous Liquid Bodies in Water, as may warrant me to say; That, by this Method, tho' not always with the same ease, we may explore the spe­cifick [Page 54] Weight of other Liquors, that are in equal Bulk heavier than Water, and yet are indisposed to mingle with it; such as are the Chymical Oyls of Cinnamon, Cloves, Guajacum, &c. But the chief thing, that has made me the the more Circumstantial in deliver­ing the foregoing Experiment, was, that this practical Direction, for weighing one Liquor in another, will hereafter appear to be applia­ble to useful Purposes, especially when we come to mention, in the following Chapters, several Cases, wherein Liquors of a Nature very different from Water, may be substitu­ted in its stead.

CHAP. IX.

AS for the Way of Examining Hydrostatically the Powders of sinking Bodies, such as Minium, Put­tie, &c. or such small Solids, or Frag­ments of greater Ones, as by reason [Page 55] of their Littleness or inconvenient Shape, are singly unfit to be tyed with an Horse-hair to the Ballance; as the Fragments of Rubies, and other pre­cious Stones, wont to be sold by Weight at the Drugsters or Apothe­caries Shops: the Way of discovering the Weight of these in Water, dif­fers not much from That lately de­livered of weighing Quick-silver in that Liquor. For on these occasions also, we imploy such a Glass-Bucket, as was lately described; and having made it very dry, as well within, as without; We put into it the Metal­line Calx, or other heavy Powder, or a convenient Quantity of the Frag­ments of Gems, or a competent Number of small, tho' intire, Bodies, as Pieces of Native Cinnabar, Seed-pearl, &c. and proceed with these, as we did with Quick-silver. Only this Caution is to be heedfully taken along, that we warily, and little by little, put into the Bucket, whilst 'tis yet kept in the Air, and hath the already weighed Powder, or Frag­ments [Page 56] in it, a convenient Quantity of the same Water, 'tis to be weighed in; that the Liquor may have time to insinuate it self between the dry Bodies, and even the Corpuscles of the Powders, and expel thence the Air, that was harbored in the Intervals betwixt them; which little Aerial Portions, if not thus seasonably ex­pelled, would, upon the immersion of the Vessel, produce in the Water store of Bubbles, that would buoy up, or fasten themselves to the Fragments, or other small Bodies, and make the Ex­periment uncertain, or fallacious. And if it be a Powder, that is to be weighed; unless it be before hand throughly wetted, and thereby freed from Aerial Particles, and reduced to a kind of Mud; there is Danger, that some dry Corpuscles of the Powder, will, when the Vessel is under Wa­ter, be buoy'd up, and get out of it, and, floating on the Surface of the incumbent Water, take off from the true Weight, that the immerst Pow­der should have in that Liquor.

[Page 57]If this Way of examining Bodies be carefully imployed by a dextrous Man, furnished with a tender Bal­lance, it may be of considerable use, not only to Physicians, Druggists, and Apothecaries, that are conver­sant with the more precious Kinds of sinking Bodies, that belong to the Materia Medica; but also to Lapida­ries, and Gold-smiths, whom it much concerns not to be imposed upon by counterfeit Gems, or by other Stones of price, that are not duly conditi­oned, in their kind. Thus the Frag­ments of the Five precious Stones, That (upon what grounds, I now inquire not,) are made Ingredients of some Noble Compositions, as Con­fectio Hyacinthi, &c. these Fragments, I say, may each sort of them apart be usefully examined by their Weight in Water, by him that knows the true specifick Gravity of a parcel of the finest, or else of such as he jud­ges to be fittest for his purpose. And, to add That upon the By, whereas Granates are reckoned among the [Page 58] Five Medicinal precious Stones, and in some Pharmacopoea's are preferr'd to the First place, as the best: I have found so great a difference, in point of Ponderosity, between European Granates and American Ones, whereof some were sent me as a Present from New England, and others, I my self pickt plentifully enough out of an odd American Mineral, that I suspe­cted to contain them; that it was very obvious to think, their Virtues might be very different, if not as to Kind, yet, at least, as to Degrees: And not only such factitious Pearls as have delu­ded many, and sometimes even fa­mous, Jewellers, (as one of themselves, that was Lapidary to a great Mo­narch, confessed to me) may often­times by this Expedient be disco­vered, especially if Mercury (tho' disguis'd) be imploy'd in making them; but, we may probably by the same Method discriminate the natu­ral Pearls of several Countries and Sorts, whereof I have seen a far grea­ter difference than one would expect; [Page 59] and I have somewhere yet by me na­tural Pearls of such various Colours, as well as Shapes, as have somewhat surprized even the Curious. But because it more concerns Physicians and Patients, to be able to make Esti­mates of Seed Pearl, that are on ma­ny occasions of good use to health; than to know the Genuineness of those bigger Ones, that are seldom made use of, but for Ornament; I shall here mention the result of an Experiment, which I find among my old Notes, to have been made by me, when I was furnished with very fine Oriental Seed-Pearls. For having examined these by the Way, we are now discoursing of, as judging them Orient enough to be fit to be Pat­terns, wherewith to compare Others; we found these to Water of the same Bulk, 2 75/100 ( i. e. ¾) to 1.

But in This, and in those other Tryals, whose Difficulty, or Impor­tance, require, that we make them as exactly, as we are able. I must advertise you, that 'tis not fit to trust [Page 60] to the Steddiness of your hand, in holding the Ballance, but that you make use of a Gibbet, (as they call it,) or some other stable Prop to sup­port it. For the Hand often shakes, and makes the Instrument that it holds, to do so: and oftner grows weary before the Scales have had time to play up and down, and at length settle in a determinate Scituation; wherein if you miss of a true Aequi­librium, the Hand must undergo a new Pennance: Whereas, when the Ballance hangs on a stable Fulcrum, you have both your Hands to help you, and need not be tempted by Weariness to desist, before the Bal­lance be brought to rest in a per­fect Aequilibrium. The Neglect or Omission of this Practice, I take to be one main Reason, (for the want of good Ballances, or of Skill to use them, is oftentimes Another) why so many of the Experiments, that re­quire weighing, are Erroneous; as they that cautiously examine them (as I have sometimes had occasion to [Page 61] do) may easily find. And therefore, (to add That, upon the By,) I hope, you will not make haste to censure the Accounts I give of Hydrostatical Tryals, because they do not always agree with Those of other Mens; since perhaps they did not imploy, either more Diligence, or better Instru­ments, than I.

CHAP. X.

THe last of the Three Cases, for­merly mentioned: Namely, What is to be done, when the Body to be Hydrostatically examined, will dis­solve in Water, or easily mingle with it? Imports a Question, difficult and trou­blesome enough to be resolved. Nor can this Examen be performed by a single Operation, which yet sufficed in each of the Two foregoing Cases. And having seriously considered the Matter, the best Expedient I could then think of was, That, which di­vers [Page 62] years ago, I propounded in an Assembly of the Royal Society, and grounded on this Reflection, That tho' the Body proposed could not be immediately weighed in Water, yet we may substitute another Liquor that will not dissolve it, and there­by investigate the specifick Gravity, in reference to that Medium; and then, by comparing the difference of those Two Liquors in point of Gra­vity, One may come to discover, What the Body proposed would have weighed in Water, in case it could have been kept there a competent time, without having any part of it dissolved. Considering then, that, except Quick-silver, the visible Fluids we can command, are either of an Aqueous, or of an Oily, Nature; and that most Bodies, whereof we can make Solutions in Liquors of the for­mer, will not (at least, sensibly) suf­fer themselves to be dissolved by those of the later, Kind, whilst a pro­posed Solid is weighing in them: We presum'd that the most Saline Bodies, [Page 63] such as Allum, Vitriol, Sal Gem, to which may be added, Borax, Subli­mate, &c. might be commodiously weighed in Oleous Liquors. Among these I made choice of Oil of Tur­pentine, rather than Oil- Olive, or any Chymical Essential Oil: Partly, because, being of common use, 'tis to be procured in sufficient Quantity, and, being very cheap, is seldom a­dulterated, as Chymical Oils are too often found to be; and, partly, be­cause being a distilled Body, it may be presumed to be free from Aqueous Parts, of which Experience has shewn me, that common expressed Oil is far from being destitute: But because Two Liquors, that are indeed both of them Oils, are wont to have distinct Names given them in the Shops; I shall here intimate, that I do not, when I have my Choice, make use of that which many call the Oil of Turpentine, but of That which first comes over, which those that distinguish them, call the Spirit of Turpentine: I prefer This, [Page 64] (I say,) because 'tis clear, almost like fair Water; whereas, That which is called the Oil, besides that 'tis less Fluid, is commonly of a Yellow Colour, which does lessen its Transparency, and may be compounded with some of the coloured Bodies to be weighed in it.

There are many Persons, that would find it very difficult, and to whom, on most occasions, 'twill not be necessary, to know the determinate Proportion in Gravity, between Oil of Turpentine, and the Solid that is weighed in it; and to discover, by the help of that Gravity, what the Bo­dy proposed would weigh in Water, in case it could be kept for a com­petent time in that Medium, with­out having any part of it dissolved therein. And therefore, Tho', if you desire it, I shall, God permitting, an­nex the Method of performing this Task (which, you know, requires more Calculation, than every com­mon Reader is able to go thorow with) to the end of this Tract: Yet, [Page 65] for the present it may perhaps be suffi­cient, as well as fit, that I give you notice, that those, that have not Skill enough to determine, by the Hydro­staticks, the Proportion between sink­ing Solids, and the Liquor they are weighed in, may yet be assisted by what we have delivered about Oil of Turpentine, to make a not unuse­ful Estimate, What is the specifick Gravity of divers Bodies, in reference to others of the same, or a differing, Species; and by that means, to make a probable Guess, Whether or no it be rightly Conditioned; if he be but provided with one piece of the Body, which he knows to be Genuine or well qualified. For This may serve him as a Standard, whereby to exa­mine other Bodies of the same De­nomination, that he may have occa­sion to Purchase, or to Sell, or to Imploy. As, suppose a Trades-man be to buy a parcel of Sublimate, he may take an Ounce, for instance, or half an Ounce of some of That he knows to be good or rightly made: Then having [Page 66] carefully weighed it in Oil of Turpen­tine, and set down how much it weighs therein; if he takes an Ounce, or half an Ounce of the Sub­limate, he would make Tryal of, he may weigh that, as he did the other, in the same Liquor, wherein if it give the same Weight with the Standard, 'tis a good Sign; but if it weighs not so much, 'tis a Sign that it has not its full or due Proportion of Mercury, and too great a Proportion of Salts, whence its comparative Lightness proceeds. The same Way of trying may be made use of, for the Examen of Mercurius Dulcis, and divers other Bodies, totally or partly, dissoluble in Water, as of Allum, which is often Sophisticated with some baser Salt; and of Roman Vitriol, which is sometimes either counter­feited, or adulterated by the help of Roch All [...]m, and a Tincture of Copper. And according as the Weight in Oyl of the Body proposed, recedes more or less from the Weight of the Stan­dard, so the Adulteration may be probably concluded to be lesser or greater.

CHAP. XI.

BEfore I go off from this Subject, 'tis fit that I give you notice, that the Hydrostaticks may supply us with another Way of Estimating the intensive Gravity of Bodies, Solid or Fluid, that may on some occasi­ons be of good use. The Way I mean is this; we take a solid Body more than heavy enough to sink in Water, and carefully observe, once for all, its Weight in the Air; then we weigh the self same Solid, first in One of the Liquors we would examine, and then in another; and so onwards, if there be more than two: And having noted the diffe­rence between the Solid, and each of the Liquors, 'tis easie to find, ac­cording to the Practice elsewhere delivered, the specifick Weight of each, and the Proportions betwixt [Page 68] them. And in regard 'tis but One and the same Solid, that is compar'd to the differing Liquors; whatso­ever their Number be, it will not be difficult, to compare the speci­fick Gravities of those Liquors be­twixt themselves, and to discover by the Weight of the First, That of any of the Others that One pleases.

The propos'd Way having been but Summarily delivered, it will not be amiss to subjoyn some Re­marks relating to it.

And First, If you intend to im­ploy but One Solid in your Examen of Liquors, 'twill be necessary you make Choice of such an one, as hath a much greater specifick Gravity, than is necessary to make it sink in Wa­ter. For there are some Liquor [...] that are far, perhaps twice, more ponderous than This newly named. Secondly, The Body ought to be hea­vy enough to sink in all Liquors but Quick-silver, (for in That, none but Gold is ponderous enough to sink.) But if your Tryals are to be made [Page 69] upon Liquors that belong to the Ve­getable, or Animal, Kingdom, the Body you imploy need not be near so ponderous; tho' it ought to be more so than Water, because (as I found by Tryals purposely made) some Liquors, that are very Spiri­tous and Volatile, are yet much hea­vier in Specie, than Water. 'Tis not very easie to pitch upon such a single Solid, as may have all the Qualities in reference to our Purpo­ses, that may be desired in it, if it be to be made use of for a long time. For Thirdly, Besides that, it ought not to lose of its Weight, (and conse­quently to change it,) by the insen­sible Avolation of Effluvia, and that it must be, as was freshly noted, of a considerable specifick Gravity. Fourthly, It ought not to be too big, or too intensely heavy, lest it be too heavy for a tender Ballance, or re­quire too much Liquor to inviron it. Fifthly, It ought to be of such a Tex­ture as not to be dissolved, or corroded by any of the several Liquors, some [Page 70] of which may be sharp and pierc­ing Menstruums, that 'tis to be weigh'd in; and those too of differing Natures. Sixthly, It should also be of such a Make, as is not easily lyable to be broken, or otherwise spoil'd, that it may last, till all the design'd Expe­riments, tho' many, be made with it. Seventhly, and lastly, 'tis desira­ble, that it should be of a natural and uniform, as to Sense, and pro­curable Substance; that the Experi­ments, made with it, may be easily enough communicated to Others, and, if they think fit, tryed over again by them; and that, if any be judged worthy, they may be transmitted to Posterity.

Several Bodies there are, that I looked upon as more fit than most Others to be imploy'd about the Tryals, we are treating of. The chie [...] of these were Brimstone, Hard Wax Ivory, and White Marble. But tho each of these, especially if fitly shaped, may be of use on some parti­cular occasions; yet every one wanted [Page 71] some of the desirable Qualifi­cations lately mentioned. And there­fore, I made much more use of Three other Bodies, not because they were such as I could Wish; but because they were the least remote from be­ing such, among those I could Pro­cure. The first of these was a piece of Amber between Three and Four Drams in Weight, of an high Yellow Colour, but very Transparent, and of an uniform Texture and conve­nient Shape. This was judged fit to be imployed, when we were to exa­mine the lighter sorts of Liquors, such as common Water, Rain-water, &c. Wine, Brandy, rectified Spirit of Wine-Vinegar, and the Liquors drawn from it, Cydar, Beer, Ale, Urine, many Waters and Spirits destilled from Bodies belonging to the Vege­table, and to the Animal, Kingdoms. But 'tis not proper for the more pon­derous kind of Liquors; since 'twill not sink to the Bottom, but float at the Top, not only of some Liquors of the Mineral Kingdom, (as will [Page 72] ere long appear;) but in several Liquors afforded us by the Saline parts of Bodies belonging to the Vegetable Kingdom; as you will find within a few Pages.

The Second Body, I imployed, was a Globular Glass, which I caused to be blown at a Lamp, and to be Her­metically sealed at the Neck, which was purposely made very short, af­ter there had been Lodged in it as much Quick-silver, and no more, as we guessed would serve to sink it in any Liquor, except Quick-silver; This, by reason of its great Bulk, in reference to its Weight, was fit to discover Differences in Weight, mi­nute enough between the Liquors 'twas weighed in; and 'twas out of Danger of being corroded, even by sharp Menstruums; and therefore, on divers occasions, I preferred this In­strument to any of the other Two; but 'tis disadvantag'd by these In­conveniencies, that 'tis difficult to be made, or procured, that 'tis hard to be preserved, being very easie to [Page 73] be broken, and that partly on this Account, and partly on Others, it can scarce be a fit Standard in refe­rence to such Observations, as are to be communicated to Others, and transmitted to Posterity.

Wherefore for Experiments that are to be imparted & recorded, I made use of a Solid, which tho' heavier in Spe­cie than was necessary to inable one to compare together the lighter sorts of Liquors, and to discover their minu­ter Disparities in point of Weight, is yet a natural Standard not subject to be broken without gross Negli­gence, nor to be dissolved, or cor­roded by the Liquors, 'twas to be immerst in, however of various Kinds, and very sharp, and ponde­rous enough to sink in all of them, except Quick-silver, and yet not near so ponderous, as the lightest Metals, or many Metalline Bodies; this Solid I speak of is Rock Chrystal, which I formerly represented, as for its Purity, Homogeneity, &c. fit to afford a Measure, to which other [Page 74] Bodies may be compar'd in Weight, and by that means among them­selves. And of this pure Concrete, we imployed an almost compleat Globe, (weighing in the Air ℥ij ʒss Grains 3,) save that it had in one part of it two small Holes near one another, and easily stopt up with hard Wax, after there had been put through them an Horse-hair, by whose means the Ball was easily fastened to the Scale from whence 'twas to hang in the Water. The bigness of this Glo­bular Body made it the more fit to dis­cover the lesser Differences between Liquors in point of intensive Gravity. But because we may have oftentimes occasion to know the Weight of Li­quors, of which, by reason of their Preciousness, or Rarity, we can com­mand but small Quantities, as it frequently happens, if we be to try the Weight of Chymical Oyls, Tin­ctures, Essences, &c. We thought fit, for such Liquors, to provide a piece of Chrystal, such as Nature had framed it, viz. an Hexagonal [Page 75] Prisme, with a kind of Pyramide at the end, which is opposite to the extream, at which 'twas broken off from the Body, it grew on. For this clear and finely shaped Chrystal, (or, what is very near of kin to it, white Amethyst) by reason of its ob­long Figure, might be commodiously weigh'd in so slender a Cylindrical Glass, as required but a small Quan­tity of Liquor to cover and surround a conveniently shap'd Body, that weighed, in the Air, but half an Ounce and sixteen Grains. And to ren­der the Observations, made with these two Bodies of Medicinal and other Li­quors, (for there are several of these Tryals, that belong not to this Tract) the more useful to Experimenters, I shall here desire you to take notice once for all, that the Ball of Chry­stal was to Water of the same Bulk, as 2 57/100 to 1 or thereabouts; and the Prismatical Oblong piece of Chry­stal was to a Quantity of the same Liquor, equal to it in Magnitude, as 2 66/100 to 1.

[Page 76]I have the more particularly deli­vered the Way of exploring the Gravity of several Liquors with one Solid, because there may be made of it a couple of Applications, that may, on several occasions, be of use, not only to Chymists, Physicians and Apothecaries, but to divers other Experimenters, that are not of either of their Professions.

These Applications do, I confess, belong to another Paper, ( viz. an Essay about some Uses of Chymistry improved) that was written divers years ago. But since, by reason of the loss of divers Leaves of it, I know not whether, much less when, 'twill come abroad, I shall at present borrow some few things of it to ac­commodate my present Design.

First then, the piece of clear Am­ber formerly mentioned, or some such convenient Body, that is not too little, nor in Specie, too heavy, may serve the Chymist, Apothecary, and others, to make probable Guesses of the Degree of Spirituosity, or of Thin­ness, [Page 77] that is to be found in many Liquors belonging to the Vegetable, or the Animal, Kingdom; which may be done with far less Error by this Way, than by those uncertain Signs, on which the common Ways of guessing are wont to be grounded. For having once provided a Liquor, by Comparison whereto One may safely make Estimates of Others of the same Kind, or Denomination, 'twill be easie, by observing the differing Weights of the Amber in several Liquors to judge of the Fine­ness of any of them in its Kind; for, Caeteris paribus, That is the thinnest, or abounds most in Spirituous parts, where the Solid weighs more than in the Other, as for instance, The Amber we imployed, that in Water weighed 6 ¾ Grains, in common Red French Wine weighed 8 ½ Grains, in common Brandy of a pretty good sort, such as that of Nantz 1 [...] 1/ [...] Grains, and in vinous Spirits highly rectified 34 1/ [...] Grains. The same Way one may imploy, to judge of [Page 78] the Strength of Spirits of Vinegar, Acetum Radicatum, &c. but with a great difference in the Application. For it may pass for a general Rule, That, 'tis probable, that, of Liquors destilled from Wine, Cydar, Ale, and other fermented Liquors, the Hydro­statical Body (if I may so call it) weighs more or less, according as the Liquor 'tis weighed in, is more or less Spirituous; but, on the con­trary, in Acid Spirits and Liquors, the less the Solid weighs, the stron­ger One may repute that Liquor to be: That greater Decrement of Weight proceeding usually from the greater Proportion, it contains, of Salts that are not Volatile.

I must not here pretermit one Conve­nience of the Way newly proposed, that may, in tract of time, save you some Money, and, at least, will ena­ble you to Husband better, than in the vulgar Method you can, Li­quors that you may have but small Quantities of, or that are worthy to be preserved. For, you know, 'tis [Page 79] usual with many Chymists, and espe­cially those that are more circum­spect than others, to try the Good­ness of their Spirit of Wine, or Bran­dy, or other Spirits drawn from fer­mented Liquors, by setting Fire to a spoonful of the Spirit to be examin'd, in order to see, how much of it is totally inflammable, and how great, or little, a Portion of Phlegm will be left behind. But, not here to mention the Scruples I propose in another Paper, about this Way of trying Ardent Spirits, I shall now only take notice, that, by the new­ly recited Way, you lose or spoil all that you try, and the better the Spirit is, the greater is your Loss, whereas by the Hydrostatical Way, the Liquor is examined without be­ing destroyed.

'Tis now fit to add, that, by the help of the foregoing Observations, One may also make Estimates of Li­quors of the same kind not destilled, whether fermented or not fermented; as several Sorts of Beer, or of Ale, or of [Page 80] Cydar, or of Juices of Apples, or of Pears, newly prest out. And the same Hydrostatical Solid may be imployed, to compare with one another, in point of intensive Weight, Liquors of differing kinds, as Wine, Beer, Ale, Meads, Cydar, Perry, Verjuice, exprest Oyls, Essential Oyls of diffe­ring Bodies, &c.

But, in case the Liquors to be im­ployed be very ponderous, Amber will not be a fit Solid to be examined about them; for I have found by Tryal, (what one would scarce sus­pect) not only that it would swim or float, in divers Liquors made by Solution of Salts, whether in the moist Air, or even in Water, such as Oil of Tartar per Deliquium, Soluti­on of Salt of Tartar in as little Wa­ter as may be, and Solution of the Salt of Pot-ashes, &c. But some destilled Liquors would not suffer my pellucid Amber to sink to the Bot­tom, as I found by Tryal made with Oil of Vitriol, with Spirit of Nitre, and even with good Spirit of Salt.

[Page 81]Besides, there may be another Use made of our Hydrostatical Solid, which may, on divers occasions, be as Ser­viceable to Experimenters in gene­ral, by assisting them to proportion, to their purposes, the Strength of the Menstruums, and other Liquors, they are to imploy; as the former use is to Destillers and Apothecaries, for discovering the Strength of the already prepared Liquors, that they would examine. For there are di­vers Experiments, that either do not succeed, or, at least, do not suc­ceed so well, unless the Menstruums, or other Liquors, imployed in ma­king them, be of a determinate De­gree of Strength, (which is usually knowable by a certain Degree of intensive Weight.) This will be the more easily granted, if (as I have elsewhere shewn) the Strength and Spirituosity even of some Li­quors, whose chief Virtue and Use is to be good Solvents, may yet be unfit to dissolve, as well because their Strength exceeds a certain Mea­sure, [Page 82] as because, by their Weakness, they fall short of it; Of this, I re­member, I gave an Instance in Aqua Fortis, whose strength, as it's Name intimates, is reckon'd the best Qua­lity it can have; for I found, that if it were rectified so much as to make it as strong, as we could, or but somewhat less strong than that, it would not dissolve Silver, but re­quired to be weakened by an Addi­tion of Water; and I found, that the Menstruum, tho' it were not much rectified, would not near so well dissolve the Filings or Raspings of crude Lead, when 'twas moderately strong and fit to dissolve Silver, as when 'twas allayed with a considera­ble Quantity of Water, especially if afforded by Rain, or by Destillation. I shall add, that, in making Extra­ctions from many vegetable Substan­ces, for Medicinal Uses, Chymists themselves may fall into a Mistake, when they affect to employ their most rectified Spirit of Wine, as the best Menstruum for their purpose: [Page 83] For the Medicinal Virtue of not a few such Bodies does not reside only in what Chymists call their Sulphur, and might perhaps more properly be called the Resinous Part, which indeed is best dissolved by such Spirit of Wine, as is carefully de­phlegm'd; but also in a more Gum­mous, and, partly perhaps, almost Mucilaginous Substance, for whose Extraction a moderately Phlegma­tick Spirit is more proper; be­cause of the Aqueous Portion, that is mingled with the inflammable One; since we see, that some Gum­mous Bodies, as Gum Arabick, Gum Tragacanth, &c. are not disposed to be dissolved by the best rectified Spirit of Wine, as they are by A­queous Liquors, as Water, weak Spirit of Wine, &c. and some, tho' dissoluble in both kinds of Menstru­ums, are yet less easily so in strong Spirit of Wine, than in waterish Menstruums; as may be observed particularly in Myrrh; for other In­stances applicable to these Adver­tisements [Page 84] belong to another Paper.

And what has been now said, may serve to persuade you, that it may be of good use, on divers Occasi­ons, to take Notice of the Degree of Strength of the Menstruum, or other Liquor, we employ about this or that nice Experiment; that when we have occasion to reiterate it to the same Purpose only, we may be able to bring the Liquor we make use of to the same Degree of Strength with That, which we for­merly emyloyed, and by which the design'd Effect was produced. But, in Experiments that should be very Critically made, 'twill not be amiss to bear in mind this Caution, that if the Liquor be very ponderous in Spe­cie, as Oil of Vitriol, or Oil of Tar­tar per del quium, 'twill be fit to put something into the Scale, from which the Solid hangs, to make Compen­sation for that part of the Hair that is immersed, since Horse-hair not being of the same Specifick Gravity with this Liquor, (tho' it be pre­sumed [Page 85] to be so with common Wa­ter) is to be considered, as a some­what lighter Body, capable of buoy­ing up the Solid a little; and therefore its Comparative Levity should be compensated.

CHAP. XII.

BEsides the Way, we come from discoursing of, there is indeed another Way, which we have, on divers Occasions, found useful, to compare different Liquors, that are of the same Magnitude, in point of Weight. This is done by successive­ly filling a Vial greater, or smaller, furnished with a pretty long and slender Cylindrical Stem, to a cer­tain stable Mark made near the Top, with the several Liquors to be com­pared together in point of Gravity.

But this Way I must here do no more than name, not so much be­cause I speak of it in a convenient [Page 86] place of another Paper, as because 'tis not Hydrostatical. But there is also another Way to discover, Whe­ther or no, Two, or more, Liquors proposed differ in Specifick Weight, and to make some, not groundless, Estimate of their Differences. This is done by a hollow Cylinder of Brass, or other Metal, made somewhat hea­vy at the bottom to make it swim upright, that sinks more, or less in several Liquors, as they are lighter, or heavier, one than another. But the diligent Mersennus himself, who proposes this Way, confesses it to be very difficult to make sure Obser­vations by it. To which, I shall therefore add but this, that, being a Metal, it may be corroded by Acid Menstruums, and if it be of Brass, or Copper, it may be wrought upon or injur'd by Urinous Men­struums, too.

What Mersennus said of this In­strument, may be applied to ano­ther, tho' differing from it, both in Shape and Matter. For 'tis made of [Page 87] two Glass Bubbles, and a very slen­der Stem, which is Hermetically Sealed with a Ballast in the lower­most of Quick-silver, to keep it stea­dy, when partly immerst in Liquors, in which this Instrument, like the Metalline Cylinder, sinks deeper in lighter Liquors, than in heavier, in a measure somewhat answerable to their Differences in Gravity. But, tho' I have, on several occasions, em­ployed these Instruments, and found them not unuseful, when I did not confine my self to One, or Two, but made use of several of different Sizes, according to the various Liquors, I was to examine; yet what you may elsewhere find about this In­strument, dispenses me from say­ing any more of it in this place, than that, for some of the ends aimed at in this Chapter, it is inferior to the Way of examining Liquors by the help of the Ballance.

There is also another Way, that is Hydrostatical, proposed by Mer­sennus, of weighing of Liquors in [Page 88] Water, and it is This; He bids you take a Glass Vial, to which, being first weighed in Air, and then in Water, you are to adjust a Stopple of Wax, or Cork, that will fit it exactly. This done, you are to fill the Vial with the Liquor you would exa­mine, so that no Air be left be­tween it, and the Stopple. The Vessel thus filled, you are to weigh in Water, and substract from its Weight there, the formerly noted Weight of the Glass it self in Wa­ter, and also That of the Stopple; which done, the remains will give the Weight of the Liquor proposed in Water. This Method I lately chanced to find propounded by (the Writer newly nam'd) the industri­ous Mersennus in his Hydraulicks; but, I remember not, that he affirms himself to have made use of it; And tho' it may be serviceable on some occasions, yet, I fear, it will be troublesome in Practice. For, (to omit some inconvenient Circum­stances) ordinary Vials, capable of [Page 89] containing a competent Quantity of Liquor, are, usually, too heavy to be imployed with tender Ballances; and common Stopples (such as Mer­sennus may be well supposed to have imployed) will be subject to divers inconveniencies; as, that they may be penetrated by some Liquors, and corroded by others, and if they be made of Cork, or of common Wax, or any other Substance lighter, in Specie, than Water, 'twill not be easie to find its specifick Gravity; espe­cially since Evaporation, and other Accidents make this it self vary; and whatever Matter, Vegetable or Ani­mal, it be made of, the Vessel will cost you two Operations, One to dis­cover the Weight of the Vessel in Wa­ter, and the Other that of the Stopple, (at that time) which is troublesome. Wherefore, when I met with this Way in the ingenious Mersennus, it seemed to me more inconvenient, than One, that, I remember, I had formerly thought of, and which I have sometimes put in Practice, by [Page 90] chusing a Vial not too large, and of a round Figure, that being the most capacious under such a Superficies, and, instead of other Stopples, fit­ting it with one of (the like) Glass, carefully ground to the Neck of it. For, by this means, the inconvenien­cies of a Stopple lighter than Water were avoided, nor would the Stop­ple alter its specifick Gravity, either by Imbibition, or Evaporation, nor would it be penetrated by the most subtil Spirits, nor corroded by the most fretting Ones. To which may be added, because, in some Cases, it may be considerable, that a Glass­stopple, as it will not be wrought on by the Liquor contained in the Vial, so it will not communicate any Tincture, or extraneous Quality, to the Liquor, which cannot be affirm­ed of a Stopple of Cork or Wax, in reference to some Subtil and very Corrosive, or otherwise very penetra­ting Liquors, this Hydrostatical Bot­tel (as for distinction sake I call it) being together with its Stopple care­fully [Page 91] weighed, First in Air, and then in Water, (that the Gravity of the whole Instrument in that Liquor may be setled once for all) we fill'd it exactly with the Liquor to be exa­mined, and so proceeded, as we if were to weigh Quck-silver according to the Manner formerly declared in the Eigth Chapter. The Weight of the given Liquor in Water being thus obtai­ned, its Proportion in Weight to Water of the same Bulk may be easily discovered by the Way for­merly delivered in the Second Chap­ter (or the Tenth Chapter.) This way of examining Liquors may, on some occasions, do good Service, and I did the rather, now and then, make use of it, because 'tis applicable to all kind of Liquors, whether heavier in Specie than Water, or lighter.

If you lay aside the Stopple, the round Ball it self may be made use of, on several Occasions, instead of that Hydrostatical Bucket, for­merly mentioned; for the weighing [Page 92] of Quck-silver, and divers heavy Powders; especially if they be Course Ones. But if the Instrument be fit­ly shaped, and not too heavy, there may belong to it a greater Conve­niency than. This. For when you have, and are willing to spare, Li­quor enough to inviron the little Bottle, it may be usefully substitu­ted to the Hydrostatical Bubble, with Quick-silver inclosed, that I former­ly recommended. For, by reason of its exact Stopple, it has no need of an Hermetick Seal, (which is not easie to be be made or procured▪) and 'tis far less Subject to be broken, than a Bubble. And yet that which I most made use of, (and which weighed a­bout ℥i ʒii [...] ss. Grains xix, or 709 Grains) being well stopt with only Air in it, would link by its own Weight in Water, and in Liquors lighter than This, as Wine, Brandy, &c. And if it were to be imployed in Liquors much more Ponderous than Water, as Aqua Fortis, Oil of Tartar perdeliquium, &c. 'twas easie [Page 93] to make it fit to be weighed in them also; by putting into it a Quantity of Quick-silver (or some other fit Body) of a determinate Weight, as two, three or four Drams, before we stopped it: Which Ba­last, when the Operation is over, may, if it be Quick-silver, be easily taken totally out, and kept apart for the like Uses: and the empty Bottle, and Stopple, may thereby become fit again, to be weighed in Water and lighter Liquors.

But notwithstanding all this, be­cause Glasses, for size, shape, and weight, fit for Ballances, tender enough, and furnisht with Glass Stopples exactly fitted to them, are very difficult to procure; and the Way it self is subject to some of the Inconveniencies, that we imputed to other Ways not long since mentioned: it seems, that, generally speaking, See the Chapter. this Way of finding the Weight of Liquors in Water, is Inferiour for common use, to those more simple Ones, that we formerly recommend­ed.

CHAP. XIII.

Use VI.HAving now laid down the Me­thod of weighing one Liquor in another, 'tis allowable, and may be fit, that we subjoyn some Appli­cation of it: Especially, because it will become me to make good, in some measure, what, I remember, I formerly hinted to you, viz. that, in the subsequent part of this Paper, there would be delivered a further Use, which may be counted the VIth. of the Hydrostaticks in exa­mining Medicinal Bodies. And tho' by the Instances we lately had oc­casion to propose in some of the Chapters preceding This, divers things referable to this Use, are set down already; Yet I should not content my Self, (as I now must do) to point at the chief Heads or Kinds of things referable to it; if, on a Sub­ject that is more fertile, than it seems, [Page 95] want of leisure did not restrain me from descending to treat of the par­ticular Instances, that belong to them.

Among the Services then, that the Hydrostaticks may do a sagacious Physician, I must not omit One, tho' it has not hitherto, that I know of, been propounded by any Author. And, I hope, you will not think it improper to be taken notice of here, tho' it do not regard only the Mate­ria Medica, but is applicable (as I may elsewhere relate that I made it) to divers Subjects, that are refera­ble to other Parts of Physiology: Since divers Bodies, that seem not so directly to regard the Materia Medica, as 'tis usually reposited in the Shops of Drugsters, have been, in some times and places, and may deservedly be now made to afford Matter for Remedies, to a free and ingenious Physician.

I consider then, that there are ma­ny Liquors, whose specifick Gravity it may be useful to know, not only, as [Page 96] it may help to distinguish Genuine, or well conditioned Ones, from Them that are not so, but for other good Purposes too.

Instances of this kind may be afforded by the Juices of Herbs and Fruits; where (according to the Di­rection given in the last Chapter) we first weigh a determinate Quantity, as an Ounce, or so many Drams, in our Hydrostatical Jar, or Bucket; and putting some Oil of Turpentine on it, we sink it warily into that Liquor; whose specifick Gravity in reference to refined Silver, clear Rock Chrystal, (or some other Body, if we know it to be as pure) has been carefully found out and registred: For, by this means, (as we have lately manifested) substituting this Oil for common Water, we may discover the specifick Gravity of Liquors, not to be weighed in Water, because they mingle with it. And thus we may find, not only the difference in Ponderosity between the Juices of [Page 97] Plants of differing kinds, as of Wormwood and Roses, and some­times of the subordinate Species of the same Genus, as of Absynthium Vulgare, Ponticum, Romanum, &c. and Roses White, Red, Damask, Yel­low, &c. but we may on some oc­casions observe, whether, and, if at all, how far, the keeping of a Juice for some time, more or less, or the Fermentation of it, or the Putrefa­ction, will alter its specifick Gravity. There are also other Liquids us'd by Physicians, and not ponderable in Water, that may be by this Way examin'd, as Honey, Vinegar, Ver­juice, &c. And by the same Way may be also discovered and compa­red, the specifick Weight of the Juices of Fruits of different kinds, as of Grapes, Apples, Pears, Quin­ces, &c. and of subordinate Species belonging to the same Genus, as the newly expressed Juices, that make Sacks, French-wines, Rhenish-wines, &c. and those Liquors, that are pressed out of several sorts of [Page 98] Apples, as Pippins, Pear-mains, John-Apples, Queen-Apples, &c. And in divers of these, a Person that is curious enough, may probably, by the Method we have been proposing, be enabled to take Notice of the Dif­ferences produced in the specifick Gravity (whose Changes are usu­ally accompanied with those of Con­sistence, &c.) in the several succes­sive States, wherein the Liquors may be found at different times; as (not to mention the Juice of unripe Grapes, viz. Verjuice) the Juice of ripe Grapes is in very differing States, when 'tis newly pressed out; when it begins to ferment; when 'tis yet but New Wine; when it has attain'd its full Maturity and Perfection; when it begins to degenerate into Ropy, prick'd Wine, &c. and when 'tis ab­solutely changed into Vinegar, or else into Vappa.

But here it ought not to be con­cealed from you, That in this kind of Experiments, to make use suc­cessfully of the Hydrostatical Bucket [Page 99] is a Task difficult enough, for Rea­sons that a few Tryals will easily dis­cover. And therefore, tho' I would not discourage the Skilful, yet for those that do not find themselves dextrous at making Experiments, I think it adviseable to imploy, in­stead of the Bucket, Amber, or some other convenient Hydrostatical So­lid, or rather (which is better) a Glass-bottle and Stopple, such as We formerly described; but as large, as may well be imploy'd without over-loading, or injuring, the Bal­lance.

CHAP XIV.

AS I thought 'twas fit to give the foregoing Advertisement, by way of Caution, in the Cases that oc­casioned it; so having considered the Nature and Scope of the Hydro­statical Experiments in General, that belong to this Essay; I shall venture [Page 100] to add for the Encouragement of those, that are better furnished with inquisitive Minds, than with nice Bal­lances; that tho' in divers Tryals, especially Those that are made about precious things, as Gold, Pearls, Diamonds and other Gems; there is no relying upon any, but very Good and tender Ballances; Yet, on many other occasions, 'tis not necessary, tho' it be desirable, that the Scales, we employ, should be extraordinary Good. And this for two Reasons: First, because many Hydrostatical Experiments are such, that a little Variation from the exact Proportion of the Solid to the Liquor, or be­tween Bodies of the same Denomi­nation, can lead us into no conside­rable Error; or, at least, not defeat the Experimenters main Design; as, with a Ballance that is not nice, One may sufficiently distinguish be­tween an human Calculus, and a Peb­ble, or other ordinary Stone; and be­tween Course and Fine, native Cin­nabar: And between a true Guinea, [Page 101] or other piece of coyned Gold, that is not very small, and a counter­feit One, of Brass, or any such mix­ture, tho' never so finely guilt.

And Secondly, Because, as there are few Physical Experiments, where­in Mathematical Preciseness is ne­cessary, and fewer wherein 'tis to be expected; So in many Hydrostati­cal Tryals, 'tis very probable, that the difference of Bodies of the same kind, or Denomination, flowing from their Compositions, and inter­nal Textures, will make a discer­nable, tho' but small, difference in their specifick Gravity: As, in Rock-Chrystal it self, we have found some pieces to be to Water, as 2 1/10, or a little more, to One; and others, to be to the same Liquor, as Two and Six, or between Six and Seven Tenths to One. And therefore, how exact soever the Ballance be, there must be some Allowance made for the diversity, that may be found in the Bodies themselves, that are exami­ned, which diversity may perhaps [Page 102] produce, at least, as great a Diffe­rence in the Proportions we seek for, as needs to be expected from a small Difference of tenderness, in the Ballances we imploy. And indeed, neither One of those Differences, nor the Other, (nor perhaps Both toge­ther,) is wont to be so considerable, as to challenge much regard in Phy­sical Experiments; or at least, as to hinder it to be true, that, on most occa­sions, the Hydrostatical Way of exa­mining the specifick Weight of Bo­dies, is preferable by far to any o­ther Way of doing it, that has been Practised.

Before I proceed to the remaining part of this Essay, it will be worth while to obviate an Objection, that I foresee may be made by Critical Naturalists, against the Method hi­therto deliver'd, of finding the Pro­portion in Weight, betwixt a sink­ing Body, and Water of the same Bulk. For it speciously may, and probably will, be objected, that, by this Method, we cannot discover [Page 103] the Proportion between a Solid Bo­dy, and Water in General; but only betwixt the proposed Body, and the particular Water 'tis weighed in; because there may be a great Dispa­rity between Liquors that are cal­led, and that deservedly, common Water. And some Travellers tell us from the Press, that the Water of an Eastern River, which, if I mi­stake not, is Ganges, is by a Fifth part lighter than our Water.

But to this plausible Objection, I have Two things to Answer.

And First, having had, upon seve­ral occasions, the Opportunity, as well as Curiosity, to examine the Weight of divers Waters, some of them taken up in Places very distant from one another; I found the diffe­rence between their specifick Gra­vities far less, than almost any Body would expect. And if I be not much deceived by my Memory, (which I must have recourse to, because I have not by me the Notes I took of those Tryals) the difference between [Page 104] VVaters, where One would expect a notable Disparity, was but about the Thousandth part (and some­times perchance very far less) of the VVeight of either. Nor did I find any Difference considerable, in refe­rence to our Question, between the VVeight of divers VVaters of diffe­ring kinds, as Spring-water, River-water, Rain-water, and Snow-water, tho' this last were somewhat lighter, than any of the rest. And having had the Curiosity to procure some VVater brought into England, if I much mis-remember not, from the River Ganges it self; I found it very little, if at all lighter, than some of our common VVaters.

And now I shall represent in the Second place, that I do not pretend, (and indeed 'tis not necessary) that the Proportion, obtainable by our Method, should have a Mathema­cal Preciseness. For in Experiments where we are to deal with gross Matter, and to imploy about it ma­terial Instruments; 'tis sufficient to [Page 105] have a Physical, and almost impos­sible to obtain (unless sometimes by Accident) a Mathematical Exact­ness; as they will scarce deny, that have, as I have done, considered, and made Tryal of the Difficulties, that oppose the Attainment of such a Preciseness.

CHAP. XV. Hydrostatical Stereometry, Applyed to the MATERIA MEDICA.

CHAP. XVI.

BUt, I perceive, that 'tis now more than time, that I should put an end to a Labour, that has, I fear, tyr'd you, because, I am sure, it has tyr'd me. And yet I dare not conclude this Tract with­out briefly answering a couple of [Page 131] Questions, that, I foresee, may justly enough be asked me by a Peruser of the foregoing Essay.

And first, I presume it may be de­manded, Whether I have proposed the best Ways that can be thought of, to examine Bodies Hydrostatically? To which Question I answer, that, upon divers Considerations, some of which have been mentioned here and there in the Body of the foregoing Essay, I did not think my self obliged solicitously to Invent, or propound, new Instru­ments for the Hydrostatical Examen of Bodies. For tho' I am not Igno­rant, that divers more curious and Artificial ways of finding out their Weight in Water, or their Solid Contents by it, may be devised by Persons more skilful and sagacious than I. And tho' also I think it not unlikely, that, when the Utility of such Practices comes to be taken no­tice of, Artificial Instruments will be found out to Facilitate, or other­wise Improve them: Yet, I thought it became me at first to propound [Page 132] only the more simple Ways of Opera­ting, as the most likely to invite the Generality of those, for whose sake this Essay is made publick; and to require, for the main part of our Ex­periments, only the Use of the Bal­lance, as an Instrument easily pro­curable, and already, for other pur­poses, in most Mens hands, without mentioning, at this time, any more Artificial Instruments; tho' some of them are such, as I have long since not only had thoughts of, but, for my own Uses, practised; which In­timation may be countenanced, if it were needful, by the mention of that little Instrument, for distin­guishing between true and counter­feit Guineas, or the like Pieces of coyn'd Gold, by the help of Water; which was several Years ago pub­lished in the Philosophical Transacti­ons, and has since (without stay­ing for my Improvements of it) been made Use of by Some, and usurp'd by Others. But of such things, no more in this place.

[Page 133]Having answered the First Que­stion, it remains, that I consider the Second, wherein tho' I shall aim at Brevity as much, as in the for­mer, yet I fear, I shall not be able to discuss it in as few Lines, as I did That. I presume then, it will be asked, What Credit may be given to the Estimates of the Weight, and Proportions of Bodies, obtained by Hy­drostatical Tryals? Since, we see, that tho' Mathematicians, not knowing, or not applying, our Observation a­bout the Specifick Gravity of Rock-Chrystal, and the Nature of Oil, especially that of Turpentine, have given us but the Proportions of Me­tals, and some very few other Fa­miliar Bodies, as the Loadstone, Wax, Hony, Oil and Wine; yet those few that have not transcrib'd from one another, differ in the Ta­bles, they have left us, of the Com­parative weight of those few Bo­dies.

This Question is so comprehen­sive, that, I think, it cannot well re­ceive [Page 134] a single Answer; and therefore, I shall offer Two things to be consi­dered about it.

And first, I freely acknowledge, that there is no exact Uniformity in the Observations delivered about the weight of Metals, a [...]d the other Bo­dies newly nam'd, among the few Authors that have written of this Subject; and there would proba­bly have been yet more Difference in their Accounts, if some, even of those Writers, had not avowedly made use, to their purposes, of as much as they thought fit of the Ta­bles of Ghetaldus.

Nay, I shall not think it very strange, if I find, that the Experi­ments of the same Man, made at di­stant times, and in other differing Circumstances, should not all of them exactly agree. For I have already noted, and, I think, in more places than One, that there will scarce be found so great an Uniformity in Qualities, and particularly in Spe­cifick weight, among Bodies of the [Page 135] same Kind or Denomination, as there is generally presum'd to be. There may be also some Difference, tho' but little, betwixt the Waters Men employ, especially if the Air be at One time (as in July) intensely hot, and at Another (as in January) ex­ceeding Cold. The Difference also of Degrees of Goodness of the Bal­lances, Men employ about nice Ex­periments, is not altogether incon­siderable. But there is a thing of greater Moment than this, towards the hindering Hydrostatical Experi­ments, and even Statical Ones them­selves, from being so accurate, as those, that are not versed in such Matters, may require. The thing I mean, is, the Difficulty of finding an exact Uniformity in Weights of the same Denomination, which, for that Reason, are vulgarly supposed to be exactly equal; But, to know how far this Supposition is to be re­ly'd on, it may at present suffice to set down some Passages of a Mathe­matician justly famous for his dili­gence, [Page 136] and who has made it his par­ticular Work to examine these Mat­ters scrupuolusly. The first Passage, I shall allege out of his Writings, shall be the short Account he gives of ma­ny Tryals he made of natural Grains, whence all sorts of weights have been deduced. In Praefa­tione ad Librum de Mensu­ris, ponde­ribus & nummis. Cùm (saith he) om­nia grana, vel semina, quae reperiri so­lent in atriis venalibus Lutetiae, ad Stateram expendissem, vixque granum ullum inter ejusdem speciei grana grano alteri exacte respondisset, in incertis ludere nolui. The same Author in­forms us, that the Roman Grains dif­fer from the French Grains; since, as, he observes, 688 Grains of the former sort, are Equiponderant but to 576 Grains of the later sort. And he subjoyns, that, whilst he was wri­ting these things, there was found by the more exact weights of the Mint, an Error in the former Estimate, of at least half a Grain in 36 Grains.

And elsewhere he gives notice, that, by two Relations, sent him from [Page 137] Rome, about the Number of Grains, Mersennus in the Pa­per entitu­led, Pari­siensia Pondera, Corollar. 1. and 2. contained in a Roman Ounce, it ap­pear'd, that even that Number vari­ed, since One of those Relations re­ckoned 612 Grains in an Ounce, whereas the other allowed it but 576 Grains. And yet this I do not wonder at, because I have my self found it so difficult in Practice, to get and keep Weights (for, as little as this is wont to be suspected, the the very Air may, in time, a little alter them,) as exact, as I desired, that I left off the hopes of it. And one Remark, tho' commonly over­looked, I think too considerable to be here omitted. For, In the Pa­per called Galic. Nummis. whereas the accurate Ghetaldus's Tables of the Weight of Metals, and some few other Bodies, in reference to one ano­ther, are looked upon as the most Au­thentick that have been published & are accordingly made the most use of: 'Tis certain, that the Weights he employ'd are not divided, as Ours are. For, tho' indeed according to him, [Page 138] as well as with us, the Ounce con­sists of Four and twenty Scruples; yet the Scruple, which with us is di­vided but into 20 Grains, he divides into 24. But to return to Mersennus, a while after he had told us of the Difference between his repeated Tryals, and Those of other Men, in determining the Weight of a certain Body, he has this Passage; which shews, that he was not over-con­fident of the Preciseness of all his own Determinations. Cum autem (saith he) pag. 37. lib. 16. Dixi, Chelin [...]m, unde­cim dici denariorum, credunt tamen alii decem dunt axat, nil assero.

Having gone thorough the First part of my Answer, to the Second Query above proposed, it remains, that I proceed to the Other part; which perhaps will not need more than the following Reflection.

I consider then, that tho' it be granted, that Hydrostatical Expe­riments are not always either singly accurate, or exactly agreeable among [Page 139] themselves; yet they may well be, both accurate enough to be of very good Use, especially in Practice; and less remote from being quite accu­rate, than any other Ways that have been hitherto known to be Practised, of determining the Proportions of Bodies in point of Weight and Bulk, and of measuring the Solid Con­tents of stable Bodies, whether hea­vier in Specie than Water, or ligh­ter.

The First part of this Reflection may be deduced, as a Corollary from, or at least confirmed by, the greatest part of the foregoing Essay. And indeed, as little Skill as I have in Hydrostaticks, I would not be debar­red from the Use of them, for a con­siderable Sum of Money; it having already done me acceptable Service, and on far more occasions, than I my self at first expected; especially in the Examen of Metals and Mine­ral Bodies, and of several Chymical Productions. And I have been able [Page 140] more than once or twice, to unde­ceive Artists and other Experimen­ters, that, bona fide, believed they had made, or were Possessors of, Luna fixa, (as they call it) and other valuable things: And to make a good Judgment of the Genuineness or Fal­sity, and the Degrees of Worth, or Strength, in their kind, of divers ri­cher or poorer Metalline Mixtures, and other Bodies, (some Solid, and some Liquid,) whose fair Appea­rances might otherwise have much puzzled, if not deceived, me.

But of This more may be found in another Paper. For I must hasten to the Second part of our designed Reflection, by representing, That our Hydrostatical Methods of disco­vering the Weights and Bulks of Bodies, tho' they be not Mathema­tically accurate, yet they are less re­mote from being so, than any Way of Mensuration of Bodies, (especi­ally such little Ones, as we usually have need to examine on the ac­count [Page 141] of the Materia Medica,) by the Geometrical Instruments, that are hitherto known to be Practised; or, by the Way, Verulam in Histo­riâ densi & rari, p. m. 8. &c. whereby the Tabula Coitionis & Expansionis Materiae per Spatia in Tangibilibus, &c. was fra­med by the renowned Sir Francis Bacon; whose judicious Reflections up­on the Rarity and Density of Bodies, such as their measures are delivered in that Table, do sufficiently manifest, as the Philosophical Genius of the Au­thor, so the Utility that may be de­rived from even such Determinati­ons of the Bulks and Weights of Bo­dies, as fall short enough of being accurate.

I might here relate, that, to con­vince some curious Persons, how much Hydrostaticks may be made serviceable to as accurate Mensura­tions, as ought to be expected in Physical Experiments; I desired a Virtuoso, First, to put together two Lumps of Metal ( viz. of Tin, and of Lead) in a certain Proportion, [Page 142] that he was to conceal from me, but to set down in Writing to prevent Mistakes. Then I desired him to melt the Metals (whose respective Spe­cifick Gravities I knew before) into one Mass, and give me that Mass. And Thirdly, I weigh'd it carefully in Water; and did also Algebraically examine it. Which being done, I told him, that the Lead, he had im­ploy'd, amounted to such a Weight, and the Tin to such another; which being compared with the Quantities he had committed to Paper, the Dif­ference was found to be little more than one Grain, and this it self pro­bably proceeded from some scarce avoidable Imperfection in the melt­ing, pouring out, &c. of the given Bodies. But because specious Arith­metick was employ'd in this Work, (to which, yet it was not absolute­ly necessary,) I shall lay no Stress upon it; because, if I mistake not, the past Discourse may suffice to give the Hydrostatical Ways, of Men­suration [Page 143] of Bodies, a preference to their Competitors; and may keep it from being presumptuous, to say, that they may be received as the best for Practice, till some other more ac­curate, and yet as firmly grounded, and as Practicable, Ways of accom­plishing the same purposes, shall be propos'd.