22 The Complete Engliñi c Difi>enfatery. Parti.

the Refinance which the Particleswill meet with in their Defcent, willbe equal to their Gravity. By this wemay underfland how the Corpuiciesof Metals fwim in Menfiruums ,which are fpecifically lighter thanthem, as Gold in the Spirit of Nitre,which is drawn off from BezoarMineral, tho' the Gravity of Goldbe i j- times greater than the Gra-vity of that. For if we were tocompute, we fnould find that be-fore the Diameter is reduced to halfwhit it was before, not only theGravity of the Cold becomes dou-ble in reipect of die Menftruum, butlikewife the Surface of 'the Gold, com-pared to its Gravity, is double. Andthe lame Reaibn holds good in al-moft all other Menfiruums.

Thus we have leen how Corpuf-cles are fulpended in Menfiruums,fpecifically lighter than themfelves."Tis for the fame Reafon, that fuchParticles as are lighter cannot riféup to the Surface : for the Preffureof Fluids being equal every way,the fùperior Parts act reciprocallyon the inferior; Co that the fameForce, which keeps the heavier Par-ticles from finking, will not permitthole which are lighter to afcend.

The Ufe of Digeftim may be un-dcrftood from the Word; namely,to extract the Particles of Bodies,which are more volatile and freedfrom the Terreftrial ones, by a cer-tain Menftruum, and to mix themimmediately with it. To this end agentle Fire is commonly uied, thatthe Corpufcles, which are moil vo-latile, may feparate as it were oftheir own accord : for a fierce Fireforces out the Faces, as well as thefiner Particles ; and if it does not a-"bate the Strength of the Liquor, itWill not fail of fpoiling its Ciearneis,

a thing which very frequently hap-pens in drawing Tinctures. Befides,if we make theFire a little too ftrong,in the management of fèveralthings,there may be danger of an Empi-reuma.

The reafon ofthat Variety, whichis obfervable in the Apparatus ofBigeftion, may be fufficiently under-ilood from what is laid elfewhcre.Thus when we melt.Wi of Tartar,and reduce Sulphur into Flower, inorder to extraer, their Tinctures, wedo it for this very reafon, that theParticles being thereby leflen'd anddivided, may more eaiily yield to theMenftruum. Crocus, Opium, Cafto-reum, ice. whole Textures are morelax and rare, do very readily, runinto Tinäures, when the Menftruumis poured upon them. Myrrh andAmbet, which are of a more firmMake and Coheiion, and come verynear the Nature of Refins, do hardlyyield to Digeftion. But if Sal Ar-moniac be mixed with them, thenthe Tincture is not only extracted/boner, but made ftronger, and fit-ter for Medicinal Ules. So that Vi-ganïs Opinion of Myrrh fèems verytrue, that iitrle or nothing, is ex-tracted in common Elixirs-, there-fore he took Myrrh, and hung it upin a little Bag, with Salt of Tartar,till fiich time as it grew löft : for bythis means it diffolves focner in Spi-rit of Wine. Whicji holds good inextracting the Tinctures of refinous,gummy, or glutinous Bodies; forthe Salt of Tartar divides and loofoisthe Cohelions of their Parts, fo thatthey are more eafily attracted by,and join with thofe of the Mtn-jhtmm. This Method of Vigani's,in making Elixirs, was borrow'dfrom Faracelfus, who fnarpen'd theSpirit of Wine with Oil of Sulphur.

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