PUR
( 9H )
PUR
-°. That a yet farther Remiflion of thefe Properties will convey it into the Blood, and allow it there to promote Evacuation by Urine. SeeURiNE and Diuretic.
And, laftly, that a ftill farther Comminution will pafs it into the minuteft Canals, whereby the fame Properties, only in a lower degree, it will caufe Sweat, or increafe Ferfpiration. See Perspiration, Sweat, Diaphore-
TIC > &"■
Hence it appears, that the more fubtile Medicines ope- rate in the Capillaries, and fmalleft Fibres by the fame Mechanifm, that the more grofs ones do in the common Stream of the Blood, when they go off by Urine ; or as rhe groffeft of all do in the greater Paffages, when they promote Evacuation by Stool. . , , .
Hence it is evident, that the Skill of preparing and adrm- niftring of Medicines confifts in proportioning their mamtelt, and known Properties to the Capacity, and C.rcumftances of the Part they are to operate in ; and to intend, or remit their mechanical Affeaions, as they are fooner or later to take place in the greater or fmaller Veffels.
Of the firft Clafs there are few to be reduced I mall enough to go beyond the larger Paffages, and none of them are worth the pains they require, to fit them farther than for Diuretics : Befides, their natural Difpofition to attraft, and join with the ferous Part of the Blood, whenever they get into that flage of Motion, runs them off by the Kid- neys, before they can undergo Comminution enough to get farther ; but if by frequent Repetitions of fuch Medicines, and an uncommon Laxity of the Paffages, any thing is paffed into the Habit, their Groffnefs fouls the delicate Strainers, which are dedin'd for their Expulfion ; and they lodge upon the Glands and Capillaries in fuch manner, as to induce Intermittents.which is obfervable in many Perfons, after along ufe of Cream of Tartar, the common cathartic Salts, and the purging Waters, efpecially at the latter end of the Summer, when the heat of the preceding Seafon has debilitated the Solids, and left 'em under too great a Relaxation.
Among the refinous Purges, there are many very power- ful ones,'but where their Operation isdefir'd in the Vifcera, Blood, and remoter parts, they muft be extremely divided; and this we find fpirituous Mendruums will do, by taking up the moil fubtile parts only, and carrying them into the very fmall Paffages, where they operate chiefly by fufion ; becaufe the foftn'efs of fuch Subtlances cannot enable them, hardly in any degree, to act as Stimuli, farther, at leaft, than as ordinary Detergents. And thus we find that Aloes, the chief of this Tribe, goes fartheft into the Habit, and continues longed e'er it operates, when managed with a fpirituous Menflruum, as in the TinBura Sacra. The Rad. Tttrfetbi, and Cobcpttlo likewife, with all of the ve- getable Kind, that will yield to a fpirituous Liquor, are, by that means, to be carry 'd into the (artheft Scenes of animal Action; where they will prove efficacious Medicines in Cafes, which, with other management, they would never be able to reach : And on this accountit multundoubtedly have been, that we frequently meet, in praaical Writers, with many Materials of this fort mention'd as Alterants ; the Colocynth particularly by Hehmnt: for all Medicines which operated in the farthett Paffages, they commonly include under that general Appellation.
But the mod efficacious Purges, and thofe which require the moil Skill, are procured from the Mineral Kingdom ; thefe abound in Solidity beyond any other Materials, and therefore wherever they are brought into Aflion, neceffarily excel in quantity of lmpulfe : Many of thefe therefore want not only theutmoft Comminution to catry them into the farther Scenes of Operation, but alfo fome rettraint of their Afperities, and Motions, to fit them for many Inten- tions, Thus Sublimate is not only to be much fweeten'd,
that is, fmooth'd in its Points, to make it a fafe Purge in the larger "Veffels ; but if it be intended to go farther than the Blood, and thofe Glands, which, in that Circuit it is moft apt to be lodged upon when it falivates, it muft not only be render'd very fine, but alfo be coyer'd with fuch Subftances as weaken its Points, and make it llrain into the laft Subdivifions of the Conftitution. To this purpofe, the common Practice wifely contrives in Diftempers, which, ac- cording to the Courfe of Circulation, lie moft remote, to wrap up the Bafis of this Medicine, in Sulphurs, and fuch like Subftances, as follow it into its laft Divifion, without giving it any Afperities to make it act as a Stimulus. Thus, for all cutaneous Foulneffes, and habitual Taints, the Cin- nabar the JLthiops, and all of that Sortment, are in readi- nefs ;' and that ordinary Sulphurs will cover and deaden the efficacies of Mercurial Preparations, fo that they ftiall not operate, but in fuch Farts only and in certain Circumftances, is demonflrable in ordinary Salivations, which are to be lower'd by Sulphureous Medicines.
Medicines from fuch Minerals, whereaSalt and Sulphur are united by Nature, as they are in fome Mercurials by Art, as in Antimony, the native Cinnabar, Steel, i$C. ate ma-
nageable only upon the fame Principles ; and the more they are defign'd to be carried into the Habit, the more are they to be reftrained by their natural, or adventitious Sulphurs : Steel, when opened by, and joined with, the Points of acid Liquors, operates the fooner, and will fometimes prove even Emetic ; but when it is cover'd with an additional Sulphur, it will go farther, and anfwer Intentions much more remote ; as is manifeft in the common Preparations of Steel, with Tartar, or Vinegar, and with Sulphur.
This way of reafoning on thefe Occafions, feems the more juft, from confidering the Textute of thofe Subftances which by a natural Preparation are fitted for Operation in the mi- nuteft part of an animal Body; fuch as thofe of the Aro- matic Kind, all which, more or lefs, according to rheir greater or leffer Degree ofSubtility and Smoothnefs, pro- mote a Diaphorefis : For thefe confift of exquilitely fine Salts, cover'd with a moft fubtile Sulphur, as is demon- ftrable by Chymical Analyfis ; and the common Sal Vola- tile Oleofum is an admirable Contrivance upon the fame Foundation, where a very volatile animal Salt is cover'd with a molt exalted vegetable Oil, whereby it is fitted to pafs into the minuteft Fibres, and make, as it were, apart of the animal Spirits themfelves,
And here it may not be amifs to obferve, that all animal Salts are very Volatile, or eafily render'd fo ; but when bare and naked, juft as the Fire draws them out, with a Mixtute alfo of its own Particles in their Compofition, they are too pungent to be felt without painful Senfations ; and when foften'd with a fine Portion of fomewhat of an eppufite Texture, which is fmooth and yielding, they become moft efficacious, and fafe Sudorifics.
On thefe Confiderations it likewife ceafes to be a won- der why the fubtile Salts of Cantharides are more fenfibly injurious to the Bladder, rhan any other Parts, and why Camphire prevents thofe Injuries ; for the exquifite Small- nefsof thofe SpicuU makes them imperceptible, but in the moft minute Canals, into which the Fibres compofing the Membranes of the Bladder are known to be divided ; and Camphire blunts their Irritations, becaufe itsexquifite Sub- tility enables it to follow them into thofe Meanders, and fheath their Afperities.
To this purpofe is very remarkable, what many now commonly praflife in guarding even Mercurials againfl their ftimulating Properties, and fending them into the fined Paffages to operate by Fufion, and the bare force of lmpulfe: For not only Calomel and the Mercurias 2)ulcis may be reftrained from manifeft Operation in the wider Paffages, and the Glands about the Mouth ; but even the mineral Turbith, which of itfelf, in a fmall Dole, will ope- rate powerfully by Vomit and Stool, will not, when mixed with Camphire, be fo much felt in thofe refpecls, but go into the fartheft Circuit of Motion, and promote the cuta- neous Difcharge in a more efficacious manner, than any
Medicine of lefs fpecific Gravity. In this Management
the Camphire is to be mixed but a very little while before taking, otherwife it hath not the effect ; which appears to proceed from its great Volatility, which makes it in a great meafure exhale while it Hands mixed in a Me- dicine.
As to the Dofes of "Purgatives, Dr. Cockburn attempts to determine 'em on the following Suppositions — 1°. That no part of 'em operate but in the Blood. a°. That they ope- rate there, by changing the Blood and other circulating Fluids derived from it.
From which 'Poflulata he concludes, that in the fame Conftitution of Blood, the Dofe requir'd to produce the like Effects, muft be proportionable ro the Blood's Quantity ; fo that where a certain Dofe is requir'd to alter one Pound of Blood, for inftance, to a certain degree, there will be requir'd a double Dofe to alter two Pounds to the fame degree, and a triple Dofe to thtee Pounds, &c. And uni- verfally if the Quantity of Blood b, require the Dofe d, the Quantity m b requires the Dofe m d. For as bid:: mb-.rnd. See Dose.
PUKGATORY, in the Romijb Church, a Place where the Juft are fuppofed to fuffer the Pains due to their Sins for which they have not fatisfy'd in this World. See Me- rits, Absolution, cifc.
'Tis by the Mercy of God, rhe Indulgences of the Church, and the Prayers of the Faithful, that People are fuppofed to be deliver'd out of Purgatory. SeelNDuL- gence, &c.
In Ireland is a Place call'd St. Patrick's Purgatory; where, as the Legend has it, at the Prayers of St. Patrick Bifliop of the Place, there was made a vifible Reprefen- tation of the Pains which the Wicked undergo after Death, in order to deter Sinners, &c.
PURGE, in Medicine, a Term frequently ufed for a purgative Medicine; as Caffia, Senna, Rhubarb, (S>c. See Purgation and Purgative.
PURIFICATION, in Cbymiftry, ejfe. the A3 of Pu- rifying, or Refining Natural Bodies ; or of feparating the
Faces
