Page:Cyclopaedia, Chambers - Volume 1.djvu/595

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fyalneum Marine or Maris, Balneum Arenofum s &c. See Balneum.

They are alfo call'd Heats ; as Sand-heat h Water- heat, &c. See Heat.

%)iftillation is two-fold, 1. Per Afcenfum, by ./7/ce^ 5 when the Matter to be diftilVd is above the Fire, and the Spirit, or other Principle, is raifed from it.

2. 'Per 'Defcenfum, by 1)efce?it; when the Matter which is to be dijttffld is below the Fire, and the Vapour drawn from it, precipitated to the Bottom of the Veflel.

Distillation by Afcent, is either Right, or Oblique.

Right Distillation, is perform'd with a common Alem- bick, or Cucurbite, wherein the Liquor is rais'd, and defcends again, in Form of Drops, into a Receiver : And is chiefly us'd when the Texture of the Body is fuch as allows of an eafy Afcentj as in Vegetables. See Alembick.

Oblique Distillation, is perform'd fide-ways, and in crooked Veffels, as Retorts. Its Ufe is for fuch Bodies as confift of heavierParticles, and which cannot be raifed without a itrong Impulfe, nor even by the ftrongeft fo high as the Top of the Alembick ; of which Kind are almoft all Minerals, and Metals. See Retort.

Distillation byDefcent, is where the Fire is apply'd on the Top, and all around the Veflel, whofe Orifice is at the Bottom ; and confequcntly, the Vapour not being able to rife upwards, it is fore'd to precipitate, and diftil down to the Bottom.

There is a fecond Kind of 2)if illation by Defcent, call'd 'Per 'Deliquium ; which is a Natural Liquifying, or Refol- ving of Salts into a Liquor, by means of Moifture. See De-

LIOJJIUM.

In the Refolution of Simples, an excellent Method to pre- ferve their Virtues, is, in lieu of Fire, or any other foreign Heat, which might alter, or deftroy thefe Virtues, to make Ufe of the Heat of a Dunghil made of putrified Herbs of the fame Kind with thofe to be dijlilled.

The Procefs, and Meafures of bif illation, are very diffe- rent, according to the different Subjects to be diftilVd.

Acid Spirits are ufually drawn in a Reverberatory Furnace, and with a vehement Fire : 'Ponderous Woods, as Guaiacum, Bex, Amber, £5V. are diftilPd in a Retort, after the fame Manner. In thefe, firft comes a little Phlegm, and then, the Fire increasing, the Spirits fly out in white Clouds. When they ceafe to come, the Matter in the Receiver is filtrated through a Tunnel, which lets pafs the Spirits, leaving a black fetid Oil behind.

Odoriferous 'Plants, as Balm, Wormwood, Sage, Hyf- fop, &c. are diJiilPd by the Cucurbite, or Vefica ; firif pour- ing a ftrong Decoction of the fame Plant hot, upon the Plant itfelf bruis'd, and letting the whole digeft in a clofe Veffcl two Days. Then about half the Water, or Spirit is drawn •away by "Diftillation ; and what remains, being prefs'd, fil- trated, and evaporated to the Confiftence of Honey, is thcEr- traB of the Plant. Laftly, drying what remain'd in the Cloth after ExprefTion, and burning it, they make a Lixi- vium of its Aihes ; which being filtrated, and evaporated to Drynefs, what remains is the fix'd Salt of the Plant.

'Plants not odoriferous, are generally manag'd thus : The Plant being pounded, and two Thirds of the Alembic, or Re- tort fill'd with it, they pour a good Quantity of the exprefs'd Juice of the fame Plant upon it, fo as the bruis'd Matter may float therein, without flicking any where to the Veffel. Then they draw off about half as much Water, as there was Juice, which is the diftilPd Water of that Plant. What remains, be- ing prefs'd in a Cloth, and the Juice fettled, they filtrate, and evaporate it to two Thirds, and fetting it in a cool Place, the Bffential Salt fhoots into Cryftals.

There is alfo a Method of Diftilling Cold ; which is thus perform'd : They take, for Inftance, 4 Pounds of Flowers, more or lefs, and put 'em in 3 or 4 Pints of Water, and the whole in a Capital, which they lute exactly; then they place the Alembick in a Veffel half fill'd with Ice, beaten and falted, as if they meant to freeze the Water ; then fit on a Receiver, and lute it well ; Then wetting a linnen Cloth in hot Water, they cover the Capital therewith, repeating this feveral times : by which means the fineft Parts are raifed from the Flowers. But Care muft be taken, that all the fuperfluous Water have been firft emptied out of the Capital.

Dr. Seal, in the Philofophical T'ranfatlious, mentions an extraordinary Kind oi Cold IJifti Hat ions, viz. made by Froft and cold Air : His Thermometer being expoied out of Doors, during the fevereFrofts of 1665 ; fine clear Drops, like Dew, afcended to the Top of the Tube, which after- wards, in time, re-defcended into the Stem, and fill'd the Space of half an Inch ; which, tho' the Spirit of Wine itfelf was tinged very deep, yet this fecond Spirit was clearer and brighter than any Cryftal. The like he did byExpofing his Thermometer to the hot Air in the middle of Summer. And hence takes Occafion to recommend a further Profe- cution of this Pfychrotechnia..

The Afcent of Fluids, we are taught by Philofophy, is ef- fected two Ways : 1, On Account of their Specific Gravity; and 2. By Impulfe,

The firft Way of Elevation is manifeft from this Lem- ma, viz. That Particles of Bodies which fwim in any Fluid, if they are fpecifically lighter, muft be born upwards by that Fluid. Hence, as dijlilled Liquors are carried upwards thro' the Air, it is to be inquired, how they come to be fpecifically lighter than Air.

Now, a Fluid will be fpecifically lighter than another, when, under a larger Surface, it has an equal, or a lefs Gra- vity -. According to this Proportion, the Bulk of the Fluid ought to be increafed in 'Diftillation ; and how eafily, by the Help of Fire, it may be increafed, or, which is the fame Thing, rarefied, will appear from what we have faid under the Articles Rarefaction, Heat, $5c.

It is known by Computation, that the Proportion of the fpecific Gravity of Water to that of Air, is fomething more than 800 to 1. Since, therefore, fimilar Spheres, or Solids, are as the Cubes of their Diameters, and the fpecific Gra- vity decrcafes reciprocally, in the very fame Proportion, as the Cubes of their Diameters increafe : In order to make a Particle of Water lighter than a Particle of Air, no more is neceffary than to rarefy it, till its Diameter becomes ten times greater, which in this Cafe is but a very fmall De- gree of Rarefaction : for the Cube of the Diameter in a Par- ticle fo rarefied, is icoo. If the Diameter be made 1 1 times greater, the Cube will be 1331 ; and if twelve, 1728. So that Water, when rarefied but 12 Degrees, will be above double lighter than Air. And if the Rarefaction be carried on farther, it may eafily be collected from the Increafe of the Numbers, that a Particle of Water may be render'd almoft infinitely lighter than Air. Now, the Elevation of Bodies equally fluid, and heavy, is always proportionable to their different Aptitude to be rarefied ; that is, they ascend quicker, upon the Application of any Force, the more fu r ccptible they are of Rarefaction : but in Bodies, whofe Aptitude to rareiy is equal, the Time of Afcent is to be determined by their fpecific Gravity. ^

But 'tis not only fpecific Gravity that ferves to elevate Bo- dies in 1)iftillation, but an external Impulfe may alfo caufe their Afcent : The Impulfe, we have here to do with, comes from the Fire, whofe" Particles, tho' extreamly fmall and. light, yet may raife Bodies much heavier than themfelves, by acting upon them with a certain Degree of Force : For fince the Moment of a Body, or that Force, by which it acts upon another, is in a compound Ratio of the Quan- tity of Matter, and Celerity ; the Celerity may be fo in- creafed, as to give a fufficient Force to the Body, tho' the Quantity of Matter in it be ever fo fmall. "Let fome heavy Body, therefore, be fuppofed to defcend, with no other Mo- ment than what it receives from its own Gravity ; in this Cafe, then, the Air, which is much lighter, may be moved with fuch Celerity, as not only to fuftain that Body, but to mount it up higher ; and the more rapid the Impetus of the Air is, or the Surface of the Body more diffufed, the higher and fwifter will the Elevation be.

So Fire, tho' it be a Body of the minuteft Size, may be moved with that Rapidity, as to acquire, and commu- nicate what Force can be defired towards removing any Obftacles. When, therefore, the Moment of Fire is aug- mented in the manner explain'd, fo as to exceed the Force of the diftilVd Body, it will remove it from its former Situation; or what is here the fame Thing, becaufe the Direction of its Motion tends upwards, will carry it up. And thus, Par- ticles fpecifically heavier than the Air contain'd in the Re- tort, as thofe of acid Spirits are, afcend by a more violent Impulfe of the Fire us'd in i L)ifiillation.

Another Thing, to be noted, is, That the fame Quantity of Matter is elevated fo much the eafier, in Proportion, as the Surface is enlarged ; for the more this is diffufed, the more Particles of Fire it receives: having, therefore, this united Force to drive it up, it more eafily afcends ; fo that, by the fame Degree of Fire, Bodies will not equally arife, tho' they are equally heavy, if there be that Difference in their Sur- faces already fuppofed.

The Air alfo has no fmall Share in the Bufinefs of Im- pulfe ; for being rarefied by the Fire, it is not only impelled upwards it felf, but carries other Particles up with it : and it may be learned by many very familiar Experiments, what Impetus Bodies fo rarefied exert. Whofoever, therefore, well confiders thefe three Things, viz. Specific Levity ; an Impel- ling Force ; and the Extent of Surface ; and what may be effected by them, and how many Ways, and in what Pro- portions all of them may be changed, will very eafily account for all the Variety, which is found in the feveral Proceffes of 7)iftillation.

DISTINCT Notion, or Idea, according to Mr. Leibnitz, is, when we can enumerate Marks and Characters enough whereby to recollect a Thing. B. gr. That a Circle is a Figure bounded with a Curve Line that returns into it felf; all the Points whereof are equally diftant from one middle Point. See Notion, and Idea.

Distinct Safe, inOpticks, is that precife Diftance from

the Pole of a convex Glafs, in which Objects, beheld through

S* it,