3 2 The Complete ILxxyfiSh.'Difpenfatory. Parti.

SECT. IX.

Of Cryfiallizatïon.

TH I S is fuch a Combinationof feline Particles, as refern-blcs the Form of Cryflal, bur vi-riouily modified, aocord.ng to theNature and Texture of the Salts.

The Method ufed herein , is this :The feline Body is diilblv'd in water ;afterwards the Solution is futer'd,which being evaporated till a littleFiim appears on the Surface, it lpon-raneouily runs into CryfiA. Dijjblu-tion and Filtration are made ulè of,that the Salts may be purg'd from alltheir Drols; for otherwise, if any fo-reign Matter ihouId get in, not onlythe Tranlparency of the Cryftalswould be impair'd, but the Figurealio mud be mangled and broken.Theié Salts therefore being in thismanner wafh'd and purg'd afreih, theWater (as being of no further ufe)is taken off by Evaporation; whichis done with a delign, that the re-maining Solution ihould be morelàturated. And this Saturation otthe Solution is neceilary, that agreater quantity of the Salts mightrun into Cryftals. Now thelè be-ing nothing elfe but a Congeries otthe fâline Particles, if the Caule ofthis Union is fhewn, you will eafilyperceive why they cannot fublidein a more diluted Menftruum. Nowthis Compoiition ariiès from thatattractive Force, by which Salts,which are near one another, do na-turally ftrive to coalefce and unite :which thçy do fo much the eafier,the nearer they are to one another .For the Force of Attraction exertingk felF moil at the point of Contact,

is the caulè of its being; little or no-es

thing, when Bodies are removed toa greater diftance. Heneé Salts, ve-ry much diluted with co'.d Water,fcarcely attrait at ail, bee míe theyare kept at too great a diftance onefrom another, and hereupon remainquiet in their refpective Situations ;and tho' the Solutions fhould beftronger, it would part with its Saltsbut very fparingly, w.tho jt Zvape-ration : but by letting the Water e-vaporate till thereappear a thin Skin,the.Sabs arc plac'd io near as jimoftto touch one another ; and conlc-quently they will attrait one ano-ther very ftrongly , and being veryclofely and intimately united, theyare fbrm'd as it were into & manylittle Lumps or Bundles.

If any faune Solution were to beleft to it felf for feme time, the Cryf-tals would precipitate, and fall oftheir own accord: for the Water,which obftruâsthe Cohefionof theSalts, does fome way or other exhale.But the very fame Salts being dif-folv'd in warm Water, do quicklyand eafily melt and .¿wim in it; nor dothey run into Cryftals, fo long asthat retains its Heat. For the Mo-tion, excited by the Heat, hindersand deftroys the Motion anfing fromthcattraäive Force. But as loon asthe Water turns cold, and the Partsof it are at reft, the Salts now beingable to approach one another, ex-ert their attractive Force, and lbunite themfclves into Cryftals.

Hitherto has been explain'd theReafon of Cryftallization : as for theFigures,