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the Chinks were exactly luted; so that before the prescribed Number of Distillations, viz. two hundred, be compleated, he concludes the Water must be all lost this way: and suggests further, that a great part of the Earth gained in such Operations, might have been collected in the Water's passing in Vapour from the Cucurbit thro’ the Alembic into the Receiver, and im

bibing the Duft out of the Air as it went along.-· Earth, Earth, which makes the Subject of the next 630. . Chapter, is held by Chemists as one of the PrinChara&ers ciples of Bodies. The Characters that distin

guish it are, “ Its being a foffil, simple, hard, “ friable Body, fixed in the Fire, not fusible us thereby, nor capable of being dissolved in

« Water, Alcohol, Oil, or Air." Virgin .. Pure, usually called Virgin-Earth, is scarce inEarth. ferior, in respect of Simplicity, to any known Procurable Body, not even Gold itself. It is procurable from all from Bodies of all the three Kingdoms-viz. Bodies. FromRain from Rain-Water, by distilling it, gathering the Water. Fæces, drying and exposing them to the Fire

till they be, as it were, burnt thereby; the Ashes hereof being purged of Salt, exhibit the pure Virgin-Earth. The like may be had by burning Ve. getables, washing the Ashes clear of Salt, &c. The Remainder is the elementary Earth; the

like may be done by the Distillation of VegeFrom Ve- tables, where, with the other Matters driven up

by Fire, as Water, Spirit, Oil, Salt, &c. there always rises an earthy Part, which upon their settling in the Receiver, sinks to the bottom, and is gathered in form of a carbonaceous Matter, which being burnt, leaves a white Earth, which when purified of its Salt, becomes a VirginEarth. Add, that if the Oil thus procured be re-distilled, a purer Oil will be hereby had ; yet

in

in this, a Quantity of Earth-may still be found, even tho' the Distillation and Rectification be repeated in infinitum, till the Oil be as subtil as Alcohol itself. So in the fixed Salts procured by burning of Vegetables, tho' there should seem to be no Earth left in them, inasmuch as the faline Part has been diffolved in Water, and paffed thro' a close Filter, which leaves only the Earth undissolved behind : yet if such Lixivium, after having stood to fettle, be again filtrated, and this repeated again and again, till it be as clear as Amber, so that if kept whole Years in a close Vessel it will not deposite the least Sediment ; it may still be brought to yield a fixed alcaline Salt, out of which a white earthy Matter may be procured. Earth again inay be pro- From Ania cured from Animals, by evaporating the vo- mals. latile Parts, as Water, Spirit, Oil, and Salt, by Putrifaction: the solid Matter remaining, is a pure Earth perfectly like that produced from Water or Vegetables.- So from Fosils, par- From Fofticularly Salts, as Nitre, Sal Gemmæ, &c. a fils, pure Earth, is procured by diffolving them in Water, then digesting, precipitating, cryftallizing thein, &c. And the like in Sulphurs, and even according to the ancient Chemists in Meta?s themselves, which however the Author disputes, judging that this Matter procured from Metals cannot with any propriety be called Earth.- .

Menstruums come next in turn, an Instrument Menf-:belonging more peculiarly, to Chemistry, and truums, which most of the Adepts give the prehemi- P. oog. nence to beyond the former four. They are

defined as, “ Bodies, which being properly ap-What, · " plied to others, divide them into minute !! Parts, so as the Particles of the Solvent be.

“ come intimately intermixed with those of

" the Body dissolved.” Name The Occasion of the Name arose hence, Menflruum that the Application of Menstruums, to the mbence.

Body to be dissolved, was chiefly excited by means of a moderate Heat, which being con tinually kept up for the space of forty Days, or a Menfis Philofopbicus; it became hence denominated a menstrual Solvent, and at length simply Menstruum. .

An essential Property of Menstruums is, that at the same time they diffolve other Bodies, they themselves are equally dissolved into their minute Parts by them: add, that many Menftruums, e'er applied to diffolve Bodies, are 'hard,

denfe, coherent Bodies ; and tho' in that Form Kinds. they cannot act as Menftruum'syet by Custom

they still retain the Name : and hence the usu

al Division of Menstruums into Solid and Fluid. Solid.

To the Class of solid, hard, or dry Menstruums belong the fix Metals, which in their cold State do not act on each other, but when fused, readily penetrate, and incorporate together. To the same also belong Semi-Metals, dry Salts and Sulphurs ; and that other kind of Foflils

usually called Cements. Fluid. To the Fluid, which is the most usual Class of

Menstruums, belong Vinegar, Water, Spirits,
Oils per Deliquium, and the like.

The Operation of Menftruums is accounted qiple. for by the Author from a Principle of Attraca ; tion, or Association, as he calls it ; whereby the

Particles of the Menstruums receding from each

other, fly towards the Particles of the Matter · to be dissolved. In effect, the Cause or Princi· ple on which the Operation depends, is as much in

The Body to be diffolved, as in the Safvent itself.

It may be added, that the Action of Menftru-
ums is always performed successively, the Sol-
vent never acting on the whole Body at once ;
and that in the progress of the Dissolution, the
Conflict, or intestine Motion increases.

For the Effeet of Menftruums, it seems to ter-Effe8,6805
minate in a new Cohesion between the Particles
of the Menstruum, and the Body diffolved, with-
out making any real Alteration in the diffolved
Particles themselves ; tho' in some cases, E.gr.
distilled Vinegar and Calx of Lead, a new Body
arises from the Solution, called Saccharum
Saturni. -

Menftruums only act by Motion, notwithstan-Operation. ding the abstruse Manners of Operation which the 683. Chemists have imagined; yet the physical Cause of this Motion is difficult to assign ; tho' in some few Instances it is evidently owing to mechanical Causes ; one of the principal whereof is Fire. But Solutions are sometimes performed by non-mechanical Causes, as in all those Instances Non-mewhere the Particles diffolved cohere with those chanical. of the Menttruum, and remain intimately intermixed, notwithstanding a Difference between their several specific Gravities ; such is that of Sal Gemmæ dissolved by Water. Of mecha-Mechanical Solutions we have an Instance in a Ball ofnical. Clay put in Water over a Fire ; when the external Action of this Fire ceases, the Clay again separates from its Solvent, and settles to the bottom... Hence Menstruums may be divided according to the different Manner of their Action, into four kinds; the first, those which act by a mere genuine, mechanical Power, and may therefore be accounted for from the usual Principles of Mechanicks.' A second is of those which to their mechanical Agency, have some further re

pelling

pelling Power superadded. A third kind is of those whose Operation' depends chiefly on the mutual Attraction between the Menstruum and the Body. The last and most usual is a compound Kind, in whose Operation all the former Conditions concur, both the mechanical, the repelling, and the attractive Powers.

The Author gives Instances of each of these Species : the Action of a merely mechanical Menstruum, he illustrates in melted Silver mixed with Water ; of a repelling Menstruum, in melted Copper and Water ; of an attractive Menstruum, in Flower of Sulphur and Quicksilver; and of an attractive, and at the same time repulsive Menftruum, in Antimony and Fire dissolved.

For the Causes and Means of the Action of Menftruums, the Author sets, in great measure, aside, that popular one of Acrimony and Corro.. fion, to which the Body of Chemists attribute all; and in lieu thereof substitutes divers others. And first, in the mechanical ones: where he thews that the hardest Bodies may indeed be diffolved even by the softeft; but then in these latter, however soft, the minute Particles are supposed. extremely hard, and even immutable ; so that he lays down the hardness of the Particles as one of the Means whereby Fluids diffolve Bodies mechanically. Another is Fire ; another

Gravity ; another Trituration. . . 709.

· In order to the mechanical Action of Menstruums, several Conditions are required: the first, a due Proportion between the Magnitude of the minute Pores of the Body to be dissol-. ved, and chose of the Menftruum. The second is an Agreement between the Figures of such Particles and Pores of the cwo Bodies. The

third,

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