Sear. 13.

Of "Dißillatton*

That other way of fining downfome Liquors, which is term'd perSubjïdentiam, is too eafy, to needany Explication: this is chiefly con-cerna in exprefs'd Juices, whicheafily let fail their grofier Parts, andthrow up fuch as are ipecificallylighter and vifcid to the Top in aScum, until they become perreâly

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fine. Where fuch things are u-fed, as add to the fpecific Weightof the groiTer Parts, and by thatmeans throw tht-m down to theBottom, as is often done in Wines,and the like, the Manner of theirInfluence will be fully explainedunder the Article of Precipita-tion.

SECT. XIII.Of Difiillation.

Dlfiillation is the Afcent and Ele-vation of Particles in form ofVaj-oar, which afterward defcendagain in the form of Drops.

This Aicent of Fluids is chieflypromoted in a two-fold way; fit ft,upon account ot their fpecific Levi-ty; and fecondly by Impuliê.

The fiift way or Elevation is ac-counted for from this Lemma,beforecited in what was faid of Fermenta-tion, viz. That Particles of Bodies,■Schick fwim in any Fluid, if theyarefpecifically lighter, muft be bornupwards by that Fluid. Thereforefrnce difiill'd Liquors are carriedupwards thro' the Air, it's to be en-quired how they can be made fpeci-hcally lighter than the Air. Now aFluid may be fpecifically lighter thananother, when under "a larger Bulk,it has an equal, or a lefs Gravity.According to this Proportion, theBulk of the Fluid ought to be in-crease in Diftillation ¡ and how ea-fily, by the help of Fire,' it may beincreaied, or, which is the famething, rarified, one who is but to-lerably vers'd in Phyfics, may com-prehend. And whoever has ob-,ferv'd a Thermometer, a Cupping-CUfs, or Boiling Water, muft be

fenfible how great a quantity oFAir,or poflibly of fome more fubdeMatter, there is contain'd in aimoftallFluids, and what a Force there isin Heat to rarify it ; at leaft, thofeprodigious Fumes which riie in theReceiver, upon difiilling Vitriol, dofufficiently prove this : for Rari-fanion is nothing but the fame quan-tity of Matter diftus'd into a greaterfpace ; fo that the fame Weight re-mains,thothe Bulk grows muchlar-ger. From whence 'tis plain, theremuft be a greater number of Poresin the rarify'd Body, which are ei -ther entirely void of Matter, or atleaft of fuch Matter as hath any con-siderable Gravity. A very clearInftance oi this may be had in theAir it felf, which is known by Ex-periments . with the Air-Fump, tohave been rarify'd to aimoft an infi-nite degree.

Having gone thus far in explain-ing this Matter, it is now to befound out, what Proportion of Rari-faition is fufficient to produce thisfpecific Levity. And that the Mat-ter may be fet in a clearer Light,let us begin with the fimpleft Bodies,and take our firft inftance fromWater. It is known by Computa-

D 4 «on.