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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 loft this way: and fuggefts further, that a great part of the Earth gained in fuch Operations, might have been collected in the Water's paffing in Vapour from the Cucurbit thro' the Alembic into the Receiver, and imbibing the Duft out of the Air as it went along.Earth, which makes the Subject of the next Chapter, is held by Chemifts as one of the PrinCharacters ciples of Bodies. The Characters that diftinguish it are," Its being a foffil, fimple, hard, "friable Body, fixed in the Fire, not fufible "thereby, nor capable of being diffolved in "Water, Alcohol, Oil, or Air."

Earth, 630.

Virgin-
Earth.

Pure, ufually called Virgin-Earth, is scarce inferior, in refpect of Simplicity, to any known Procurable Body, not even Gold itfelf. It is procurable from all from Bodies of all the three Kingdoms,-viz. From Rain-from Rain-Water, by diftilling it, gathering the

Bodies.

Water.

Fæces, drying and expofing 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 Vegetables, washing the Ashes clear of Salt, &c. The Remainder is the elementary Earth; the like may be done by the Diftillation of VegeFrom Ve- tables, where, with the other Matters driven up getables. by Fire, as Water, Spirit, Oil, Salt, &c. there always rises an earthy Part, which upon their fettling in the Receiver, finks 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-diftilled, a purer Oil will be hereby had; yet

in

in this, a Quantity of Earth-may ftill be found, even tho' the Diftillation and Rectification be repeated in infinitum, till the Oil be as fubtil as Alcohol itfelf. So in the fixed Salts procured by burning of Vegetables, tho' there should seem to be no Earth left in them, inafmuch as the faline Part has been diffolved in Water, and paffed thro' a close Filter, which leaves only the Earth undiffolved behind: yet if fuch 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 clofe Veffel it will not depofite 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 may be pro- From Anicured from Anicals, by evaporating the vo-mals. latile Parts, as Water, Spirit, Oil, and Salt, by Putrifaction: the folid Matter remaining, is a pure Earth perfectly like that produced from Water or Vegetables. So from Foffils, par- From Fof ticularly Salts, as Nitre, Sal Gemmæ, &c. afils. pure Earth, is procured by diffolving them in Water, then digefting, precipitating, cryftallizing them, &c. And the like in Sulphurs, and even according to the antient Chemifts in Metals themselves; which however the Author difputes, judging that this Matter procured from Metals cannot with any propriety be called Earth.

Menftruums come next in turn, an Inftrument Menfbelonging more peculiarly to Chemistry, and truums, which most of the Adepts give the prehemi- P. 669. nence to beyond the former four. They are: defined as, Bodies, which being properly ap- What, "plied to others, divide them into minute "Parts, fo as the Particles of the Solvent be

come

Name

whence.

"come intimately intermixed with thofe of "the Body diffolved.”—

The Occafion of the Name arofe hence, Menftruum that the Application of Menftruums, to the Body to be diffolved, was chiefly excited by means of a moderate Heat, which being continually kept up for the fpace of forty Days, or a Menfis Philofophicus; it became hence denominated a menftrual Solvent, and at length fimply Menstruum.

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An effential Property of Menftruums is, that at the fame time they diffolve other Bodies, they themfelves are equally diffolved into their minute Parts by them: add, that many Menstruums, e'er applied to diffolve Bodies, are hard, denfe, coherent Bodies; and tho' in that Form they cannot act as Menftruum, yet by Custom they still retain the Name: and hence the ufual Divifion of Menftruums into Solid and Fluid.

To the Clafs of folid, hard, or dry Menftruums 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 fame alfo belong Semi-Metals, dry Salts and Sulphurs; and that other kind of Foffils ufually called Cements.

To the Fluid, which is the most usual Class of Menftruums, belong Vinegar, Water, Spirits, Oils per Deliquium, and the like.

The Operation of Menftruums is accounted for by the Author from a Principle of Attrac tion, or Affociation, as he calls it; whereby the Particles of the Menftruums receding from each other, fly towards the Particles of the Matter to be diffolved. In effect, the Caufe or Principle on which the Operation depends, is as much in the Body to be diffolved, as in the Solvent itself.

It

may

It be added, that the Action of Menftruums is always performed fucceffively, the Solvent never acting on the whole Body at once; and that in the progrefs of the Diffolution, the Conflict, or inteftine Motion increases.

For the Effect of Menftruums, it seems to ter- Effect,680 minate in a new Cohesion between the Particles of the Menftruum, and the Body diffolved, without making any real Alteration in the diffolved Particles themselves; tho' in fome cafes, E. gr. diftilled Vinegar and Calx of Lead, a new Body arifes from the Solution, called Saccharum Saturni.

Menftruums only act by Motion, notwithstan-Operation. ding the abftrufe Manners of Operation which the 683. Chemifts have imagined; yet the phyfical Cause of this Motion is difficult to affign; tho' in fome few Instances it is evidently owing to mechanical Causes; one of the principal whereof is Fire. But Solutions are fometimes performed by non-mechanical Caufes, as in all those Inftances Non-mewhere the Particles diffolved cohere with those chanical. of the Menftruum, and remain intimately intermixed, notwithstanding a Difference between their several specific Gravities; fuch is that of Sal Gemma diffolved by Water. Of mecha- Mechanical Solutions we have an Inftance 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 fettles to the bottom. Hence Menftruums 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 ufual Principles, of Mechanicks. A fecond is of those which to their mechanical Agency, have fome further repelling

709.

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

The Author gives Inftances of each of these Species: the Action of a merely mechanical Menftruum, he illuftrates in melted Silver mixed with Water; of a repelling Menftruum, in melted Copper and Water; of an attractive Menftruum, in Flower of Sulphur and Quickfilver; and of an attractive, and at the fame time repulfive Menftruum, in Antimony and Fire diffolved.

For the Caufes and Means of the Action of Menftruums, the Author fets, in great meafure, afide, that popular one of Acrimony and Corrofion, to which the Body of Chemifts attribute all; and in lieu thereof fubftitutes divers others. And firft, in the mechanical ones: where he fhews that the hardest Bodies may indeed be diffolved even by the fofteft; but then in these latter, however foft, the minute Particles are fuppofed extremely hard, and even immutable; fo 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.

In order to the mechanical Action of Menftruums, feveral Conditions are required: the first, a due Proportion between the Magnitude of the minute Pores of the Body to be diffolved, and those of the Menftruum. The fecond is an Agreement between the Figures of fuch. Particles and Pores of the two Bodies. The third

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