OCR Text |
Show Pe mT A TT PG FO The Corpufcular Philofophy, beforeit wa: wonderfully improv’d by Sir I/zac Newtoy did not go to the Bottom of this Matter, for it gave no Account of the Caufe ofthe chief for it is found in the Diftillation of Olive Oil, (which is a Fluid made onlyby Preffure) that moft of the Oil will, by the Action of the Parts of the Fire (if it be done in a Retort) be turn’d into a kind of confiftent Subftance like Condition requifite to conftitute a fluid Body. Butter. viz. the various Motions and Agitations ofits Likewife Mercury, whofe Parts are without Particles: But this mayin a great meafure he doubt much groffer than thofe of Oil and accountedfor,if it be {uppos’d to be one ofthe primary Laws of Nature; that as all Particles Water,is yet more fluid than eitherof them. adly, It feems requifite to F/uidity that there of Matter do attract one another, when they be Store of Vacuities, or vacant Spaces inter- come within a certain Diftance, fo likewife Body, for elfe there will not be Room for each Particle to continue its Motion and Agitation on the Surfaces of the neighbouring at all greater Diftances from one another. For then tho’ their common Gravity may keep themtogether in a Mais (it mayfome- ones. times be) together with the Preffure of other fpers’d between the Corpufcles of the fluid they do fly away from and avoid one another For, 3dly, ‘The chief Condition requifite to conftitute a fluid Bodyis, that its Particles be agi- Bodies upon them, yet their continual Endeavours to avoid one another /j proper Motion, or by fomething of Subftance that tumbles them upand down byits Paflage through them, That this Qualification is chiefly requifite to Fluidity, you may gather from that common Experiment ofputting a little dry Powder of Alabafier, or Platter of Paris finely fifted in a flat-bottom’d Veffel over the Fire, for in a Boi mw Ret as little time it will boil like Water, and imitate all the Motions of a boiling Liquor; it will tumble varioufly overin great Waves like that ; it will bear ftirring with a Stick or Ladle without refifting, as it will do when cold ; nay, ifit beftirr’d ftrongly near the Side of the Veffel, its Waves will apparently dath up gainft the Sides; yet ifany of it be {peedily taken out, andlaid on a Piece of Paper, you will fee nothing but a dry Powder. So that it is evident from hence, that there is a real Difference between a fluid Body anda wetting Liquor; for not only this boiling Powder and melted Metals, but the Air and Ether, and even Flame itfelf are properly fluid Bodies, tho’ not moift Liquors. This ingenious Gentleman found alfo, that by blowing the Smoke of Rofemary into a Glafs Pipe, and then holding the Pipe (when fill’d) upright, the Surface of the Smoke would ac- commodate its felf to a level Situation ; and which Wayfoever the ‘Tube was inclin’d, the Superficies of the Smoke would be parallel to the Horizon-; and when the Glafs was much inclin’d, would run along it like Water. From whence he infers, that in order to the rendring a Body fluid, there is no need that its Parts fhould be clofely condens’d as thofe of Water are. And Dr, Hook, in his Micograph. p. 12 preients us witha very pretty Experiment & Baro Provethis Account ofFluid, ty, viz. That piedneers Drum-head, briskee Milla? he Sticks; or on the upper Stone of a Mill, turning fiv iftly round on the (empty) lower one, itin all refpects emulates the Propertics of a fluid Body ; fora heavy Body wi immediately fink a t a re alee © the Bottom, and ee emerge to the Top ; each Grain of Sand hath a conitant vibrating, dancing M tion; and if a Hole be made in. I BADE MGs Dith,) the Sand will {p; ih Eseries Pin out like Water, Ty, and the adventitious Impulfes of Light, Heat,orother external Caufes, may make the Particles of Fluids continually move round about one an: other, and fo producethis Quality. It is, indeed, a Difficulty not eafilygot over, to account for the Particles of Fluids always keeping at fuch a Diftance from oneanother, as not to come within the Sphere of one another’s Attraction. The Fabrick and Conftitution of that fluid tated varioufly andapart, either bytheir own Body, Water, is amazing ; that a Body fo very rare, and which has a vaft Over-proportion of Pores, or interfpers’d Vacuity to folid Matter, fhould yet be perfeétly incompreffible by the greateft Force, and yet this Fluid is eafily reducible into that firm, tranfparent, friable Body, which we call Ice, by being only expos’d toa certain Degree ofCold. One would think, that tho’ the Particles of Water cannot come near enoughto attract each other, yet the intervening frigorifick Matter doth, by being mingled per minima, ftrongly atcra& them, and is it {elf likewile ftrongly attracted by them, and fo wedgesof fixes all the Maf3 into a firm Body ;, which folid Body lofes its Solidity again, when by Heat the Vinentum’is folved, and thele frigorifick Particles are disjoin’d from thofe of the Water, and are forc’d to fly out of it; and, perhaps, juft thus may the Fumesof Lead fx Quickfilver. : Whena firm folid Body, fuch as a Metal, is by Heat reduc’d into a Fluid, doth not the Fire disjoin and feparate its conftituent Particles, which mutual Attrattion causd t0 cohere before, and keep them fuch a Diftance from each other, as that they are without the Sphere ofone another’s Attraction as long 48 that violent Motion lafts? And don’t they» when that is over, and the Heat is flownout, come nearer to, attract one another, and coa- lefce again? As therefore the Caufe of Cohefion of the Parts of folid Bodies appears to be their mu- tual Attraction, fo the chief Caufe of Fluidity feems to be a contrary Motion imprefs'd of the Particles of Fluids, by which they avoid and fly one another, as foon as they come ats and as long as they keep at fuch a Diftance from eachother, i The Species are; Tt is obferv’d alfo in Fluids, that the Direétion oftheir Preflure againft the Veffels which contain them, is in Lines perpendicular Common Fennel being the neceflary Refult of the Particles of any Fluids being {pherical, it fhews that the Parts of all Fluids are fo, or of a Figure CommonFennel, with Dark-green Leaves. 3. Fornrcuium; dulce C. B. Sweet Fennel. 4. Fornicutum; /fylveftre. C. B. Wild nearly approaching thereto. Fennel. that they may be eafily agitated by Heat, and mine, oblongo, gufto, acuto. C. B, Finochia; vulgo. The fir Sort is fo common in England, to the Sides of fuch Veffels; which Property Dr. Clark fays, Vhat if the Parts of a Body do not touch each other, or eafily flide over one another, and are of {uch a Magnitude as the Heat be fufficiently great to agitate them; though perhaps it maybe lefs than fuffices to prevent Waterfromfreezing ; or even though the Parts be not a@ually mov’d, yet if they be (mall, fmooth, flippery, and of fuch a Figure and Magnitude, as difpofes them to move and give Way, that Body is fluid : Andyet the Particles of fuch fluid Bodies, do in fome mea{ure cohere ; as is evident hence, that Mercury, when well purg’d of Air, be fuftain’d in the Barometer to the it offixty or feventy Inches; that Water will afcend in capillary Tubes, even in vacuo ; and that the Drops of Liquors in vacuo run pherical Form, as adhering by fome mutual Cohefion, like that between polifh’d Marble Planes. To this may be added, That thefe fluid Bodies, if they confift of Particles, which are eafily entangled with each other, as Oi/; or if theybe capable of being ftiffened by Cold, and joined by the Interpofition of certain Cuner or Wedges, as Water, they are eafily render’d hard: but if their Particles are fuch as can neither be entangled, as Air, nor ftif- fen’d by Cold, as kfilver, then they never growhard and fix’d. ~ In fhort, the Cartefians define a Fluid to be > Parts of which are in continual inteft Motior and Dr. Hook, Mr. Boyle, and Dr. Boerhaave, tho’ theydiffer inOpinion widlely from Cartefiani{m, fubfcribe to the ition, and edge Arguments to prove Parts of Fluids 13 and even that conftitutes F/uidity ; alcribes this and all are in continual it is this Motion and the latter of Motion to Fire. then are either natural, as Water, or animal, as Blood, Milk, Bile, wey &c. or factitious, as Wines, Cees 1. Fornrcurum ; vulgare, Germanicum. C. B. 2. Fountcutum; folits atrovirentibys, H.Edin: 5. An Forntcutum; vulgare, Italicum, fe~ that it will be needlefs to fay any thing concerning it. The fecond Sort is a Variety of the firft; which is very common amongit it in moft Gardens in £ d. The third Sort is the Sweet Fennel, whofe Seeds are us'd in Medicine: This is by many People fuppos’d to be only a Variety of the common Sort, or at leaft thar the common Sort is a Degeneracy from it; but this is 2 great Miftake, for the Sweet Feunel is an annual Plant, and never furvives a Winter with us, whereas the commonSort will abide nany Years. The firft and fecond Sorts are promifcuoufly brought to the Markets for Kitchen Ufes. Thefe are propagated byfowing their Seeds foon after they are ripe; and when the Plants are come up, they fhould be either tranfplanted, or hoed out to the Diftance of fixteen or eighteen Inches, Plant from Plant, for they will fpread and increafe in Bulk greatly : Their Roots will abide many Years, but you muft be careful not to fuffer their Seeds to fhed upon the Ground; for the Plants will come up and over-runevery thing that grows near them, and they are with much Difficulty exticpated. The Sweet Fennel is an Annual, and mutt be fown upon a warmSoil, and in an open Situation in February or the Beginning of March; and when thefe Plants are come up, they fhould be hoed out to ten Inches or a Foot Diftance from each other, and kept clear from Weeds: In Auguft this Plant will perfec its Seeds, and foon after the Roots will decay. The Seeds of this Plant which are fav’d in England, are not near fo good as thofe which are brought from Abroad, which are generally imported at a very rea~ fonable Price, fo that it is not worth cultivating with us. The Finochia is a Plant whichof late Years FOENICULUM;; [This Plant feems to Name of Fenum, Lat. Hay, q. d. /mall but fome derive it from / , this Plant fows it felf among others, €comes fruitful, or becaufe it provokes z in Men.) Fennel. has been introduc’d into the Exglifh Gardens, where it is cultivated as a Salad-herb, and is by fome People very much efteem’d, tho’ the Gen ty of Englijh Palates do not at prefent relifh it ; but fince it is likely to become of more general Ufe, I fhall give 2 iébors are ; fhort Account of its Culture. Firft, you muft vide your felf with 2 ferous Plant, whofe Leave. e ws Fags: The Petals of Parcel 0d Seeds from “aly, for thofe fav'd ave intire, and placd orbicularly, in Exgland are very apt to degenerate: In Fe~ for the firft Crop, ig in fire of a Rofe: Each F bruarvy i you rm Situation, and which fho 2 § vi he manner of doing plain upon 1p having well dug and levell’d |