Page:Cyclopaedia, Chambers - Volume 1.djvu/582

 DIG

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DIG

WicReiluin, to vetlicate the Mufclcs thereof, inddifpofe 'em to relax, and thus to apprize Nature of a Neceffity to dil- tharsre. See Excrement. ,

The Separation of the Urine from the Blood, may be efteem'd a Part of perfefl Digeftion; the Defign of Men Separation being to render the Blood more pure arid bal- famic, and of Conference more fit for Nutrinon; wh.cn the Salts the Urine abounds withal greatly prevented. This Se- paration is thus perform'd : The Branches of the ernulgent Arteries which terminate in the Glands, whereof the Sub- fiance of the Kidneys is compofed, carry the Blood thither ; where a Scrofity is feparated from the Blood, by means of the Pores in the Glands of the Kidneys ; thofe Pores reprtfent- ing the Holes in a Sieve, which only let pafs fuch Things as are of a lefs Diameter than themielves. This Serofity, call'd Urine is difcharged hence into feveral little Tubes, which ioynin'o into a Kind of Pyramids, yield their Humour into the 'Pelvis, whence it runs through the Ureters into the Bladder. See Urine.

Digestion, in Chymiftry, is a Preparation of Plants, Mi- nerals, Metals, and other Bodies beaten, or ground, by put- ting 'cm in a Veffcl, and heating them gradually over a gentle Fire, like the Heat of an Animal Body. See Fire.

2)i»efiion is a previous Kind of Difpofition to a perfect Diflbfution of a Body, made by means of Fire, or fiery Par- ticles, beating and loofening the Pores of the Body, and at- tenuating the Parts of the Fluids, that their Connexion with the harder Matter may be more eafily, and perfeflly diflolved. So/jakis feems to defcribe it pretty adequately by an mfen- fiblc Action and ReaBion of the Panicles of a Mafs, mo- vino together by fome fubtile, ambient Fluid, to which it was exp'ofed for Digeftion. By calling Digeftion a reciprocal Ac- tion, their Motion is intimated, by means whereof they are torn' from the contiguous Ones ; and in a Word, differently modified : So that the Motion ended, the digefledMafs, dif- fers either wholly, or in Part, from the fame Mafs before D'neRion ■ fometimes in Colour, fometimes in Smell, fome- times in Tranfparency, fometimes in Tafle, fometimes in Con- fiflence and other AtTeftions. That Digeftion is effefled by Motion is evident from an Obfervation of Dr. Grew ; who bringing a Mixture of Salt of Tartar, and Oil of Turpentine feveral Days Journey with him in a Coach to London, found it had undergone a more intimate Mixion, than if it had been expofed to a°long Digeftion. ,,.,,,

Digeftign is ordinarily confounded with Maceration; but the two Things differ, in that there is Heat required to Di- gestion ; whereas Maceration is done in the Cold. See Ma-

CERATION. . rr

Di'eftion is ufually perform d with the Addition oi iome Menttnmm fuitable to the Matter : Thus, Rofes and Pop- pics Heads are put to digefi in Oil, or Water, to make TJn- oeents or Syrups ; Calcined Lead, and Cerufs, are digefted fn diftill'd Vinegar, to make the Magiftery thereof, or theeTfl/ Satnrni. Hence Dr. gllincy defines Digeftion to be the Solution of Bodies, made by Menftmum's, with the Afhilance

To conceive the Nature of ChymialDigeftiou, it may be neccflary to fhew, how the Particles ot Bodies can by this Procefs be diffufed every Way, and fuftain'd in the Men- ftrmw ; which deferves the more to be accounted for, be- caufe thofe folid Particles have not the fame fpecific Gravity, as the Liquors have in which they fwim. Tho' the Nature of a pcrfeftly fluid Body be fuch, as that the Particles, which conftitute it, do very readily give Way upon the imalleft Im- pulfe and recede from one another ; yet thete is found in moll Liquors fome Degree of Tenacity ; and from hence arifes fuch a Cohcfion of Parts, as cannot be broken without fome Force. And tho' indeed this Force of Cohefion in Li- quors feems to be but little, or none at all, when compared with what we experience in Solids, yet we find, it can make fome Refiilance. And as the Force in Liquors is either ftronger or weaker, fo it produces a Variety ofEffefls, differing more or lefs from the Phenomena, which would naturally flow from a perfeft Fluid; So that, tho' by the Laws of Hydroftaticks, every Corpufcle, how fubtil foever, if put into a Fluid, which is fpecifically lighter, muft neceffarily fink to the Bottom; yet we find fome heavy Bodies, fuch as Gold, iSc. when re- duced into thin Plates, will be fuftained in Spirit of Wine. This Force, therefore, of Tenacity, which refitts the Motion of Bodies in a Fluid, is proportional to the Number of Parts, which are to be feparated, or to the Surface of the Body, which we would have move in the Fluid. Hence it is, that fince the Surface of a Body may be enlarged, without alter- in" any Thing of its Gravity, the Refiftance of a Fluid may be"fo auomented, as to equal the Force of Gravity, which carries the Body downwards. And a Body, tho' fpecifically heavier than a Fluid, in which it is immerfed, may be very well fuftained in that Fluid, provided it be reduced into very fmall Particles; becaufe the Gravity of a Body thus reduced into fmall Particles, decreafes in a much greater Proportion, than the Surface does, or, which is proportional to it, the

Tenacity of the Fluid : So that at length the Refiftance arifing from its Tenacity, will be equal to the Gravity of the Particle and fo hinder its Defcent. And, therefore, both in Solution, and Digeftion, it is a general Rule, that if the Gra- vity of a Body be to the Tenacity of the Fluid, as P to i ; and if the Body be then fubdivided, fo that the Diameters of the Parts be to that of the whole, as i to P ; the Refiftance which the Particles will meet with in their Defcent, will be equal to their Gravity : for fince their Weight is ±, but their Surface *, the Gravity will be to the Refiftance as ^, to ± ;i or as i to i. So that by this we may underftand, how the Corpufclcs of Metals fwim in Menftrtmm's, which are fpe- cifically lighter, as Gold in the Spirit of Nitre, which is> drawn off from Bezoar Mineral, tho' the Gravity of Gold be 1 5 times greater. And in the fame manner we may under- ftand, how Corpufclcs fpecifically heavier, are fufpended in any other Menflrimm. And it is for the fameReafon, that fuch as are lighter, cannot rife up to the Surface : for the Preffure of Fluids being equal every Way, the fuperior Parts aft reciprocally on the inferior ; fo that the iame Force, which keeps the heavy Particles from finking, will not per- mit thofe, which are lighter, to afcend.

TheUfcofZ^ejttoa; in Pharmacy, is, to extract the Par- ticles, which are more volatile, by a certain Menftruwn, and to mix them intimately with it. To this End a gentle Fire is commonly ufed, that the Corpufcles, which arc molt volatile, may feparate, as it were of their own Accord : for a fierce Fire forces out the Freces, as well as the finer Parti- cles ; and if it does not abate the Strength of the Liquor, it will not fail of fpoiling its Clearnefs.

Dicestion, in Chirurgery, is applied to Impofthumes, or AbfceHes; and exprefles their Difpofition to ripen, and come to Suppuration. See Digestive.

Tumors arifing on the. Parotides of Children, are of eafy Digeftion: They ripen in a little Time. Dionis.

Digestion is alio n^A (or Maturation, or that State of aDifeafe, wherein the morbific Matter is fo changed in Bulk, Figure, Cohefion, Mobility, (3c. by the Ufe of proper Me- dicines, or even by the Force of Nature, as to be lefs noxious and hurtful, and confequently to abate the Violence of the Diftemper. See Maturation.

The Greeks call it «mV/ms. The Matter of the Difeafe fo far digefted, as to become next a-kin to falubrious, or healthy Matter, is laid to be refolved. See Cruditi, and Crisis.

DIGESTIVE. The ancient Philofophers admitted a 1)i- zellive Faculty, or Quality in rhe Body ; as not knowing how otherwife to account for the Aft oiDlgefilon. See Fa- cult y, and Digestion. . . . ,.

Digestive is alfo ufed in Medicine for fuch Remedies as ftrengthen, and increafe the lone of the Stomach, and af- fift in the Digeftion of Foods. To this Clafs belong all Sto- machicks, and Strengthened or Corroborants. See Stoma- chic, and Strengthener.

Digestive, in Chirurgery, is a Sort of Unguent, Plafter, or the like, that ripens, and prepares the Matter of Wounds, (Sc. for Suppuration. It is ufually compofed of Turpentine, Yolk of E»gs, Oil of Hypericum, Ungnentum Bafilicum, and Tinccfure of Aloes. The Wound muft be drefs'd the firft Day with a Digeftive, to bring it to Suppuration.

DIGITATED, among Botanifts, is applied to the Leaf of a Plant which is either compofed of many fimple Leaves fet together upon one Foot-Stalk, as in the Cinque-toil, Vet- ches iSc or elfe when there are many deep Gathes, or Cuts' in the Leaf, as in thofe of Straw-berries, Hops, Vc. See Leaf.

DIGIT, Digitus, in Anatomy. See Finger.

Digit in Aftronomy, is the Meafure whereby we effi- mate Eclipfes ; amounting to the nth Part of the Diameter of the Luminary eclipfed.

The Diameter of the Bodv, or Dift of the Sun, or Moon,

is divided into 12 Parts, a\Vi Digits; and an Eclip.'e is

faid to be of ten Digits, when ten of thofe Parts are hid.

See Eclipse. „ . _•. ...

Thefe Digits, Wolflus, and fome others, call Digiti

Diolli in Arithmetick, fignifies any Integer under Ten, as i a, J, 4, 5, ff, 7, 8, Q. See Units.

Digit, is alfo a Meafure taken from, the Breadth of the

VU TDkit is properly 3 Fourths of an Inch, and contains 4 Grains of Barley, laid breadth-wife fo as to touch each other. See Measure. ,

DIGLYPH, a Kind of imperfect Triglyph, confole, or the like, with only two Channels, or Engravings. See Iri-

"dIGNITARY, in the Canon Law, and particularly in

Chapters, a Perfon who holds a Dignity, that is, a Benefice,

which "ives him Pre-eminence in the Choir above mere Prieft s,

. and Canons. Such is a Dean, and Arch-deacon ; tho the