5i The U^atural Hijlory 



are all covered with ftone, and hang down the bank like fo many 

 Ificles ; and the Earth it felf over which it glides, as 'twere foli- 

 ated over with a cruft of ftone like the Mofco petrofo of F err ante 

 hnperato*. Which brings me to a clofer consideration of waters, 

 as they are eminently endued with any peculiar qualities, of Pe- 

 trification, Saltnefs, or Medicinal ufe ; of which in their order as 

 briefly as may be. 



23. Of Petrifying waters, though I doubt not but their kinds 

 are as various,as the effe&s they produce ; and theeffe&s again, as 

 the fubjefts they work on ; yet I am inclined to believe that they 

 all agree thus far, that they proceed in the main from the fame 

 frock and linage, and are all more or lefs of the kindred of Salts, 

 which fublimed and rarified in the bowels of the Earth into an 

 invifible fteam, are received by the waters as their moft agreeable 

 vehicle, and brought hither to us at the riling of Springs, as in- 

 vifibly as the particles of filver or gold, when each is diflblved 

 in its proper menfiruum : where meeting perchance with an am- 

 bient Air, much colder and chilling than any under ground, in 

 alllikelyhood are precipitated, and thrown down on fuch fub- 

 je&s, as they cafually find at the place of their exit, which they 

 prefently cloath with a cruft of ftone; or elfe (where precipita- 

 tion or cohefion will not fuftice) they pafs with the waters through 

 the pores of the fubjefts, and are left behind in them juft as in a 

 filter. 



24. The reafon of which difference may probably be, that 

 fomeof thtft petrifying fteams or atoms, may be grofs and more 

 bulky than fome others are, and cannot be held up in the watry 

 vehicle, without fuch a heat as they have under ground, but fall, 

 and by reafon of their bignefs, do not penetrate, but adhere to 

 their fubje&s whereas others that are fine, more minute and fub- 

 tile, are eafily fupported in a volatile condition, and pafs with 

 the waters into the clofeft textures. 



25. If any body doubt whether ftones, and fa petrifications, 

 arife from Salts, let him but confult the Chymifis, and afk, Whe- 

 ther they find not all /Wr<7/eiBodies,fuch as ftones, bones,ftielIs, 

 and the like, moft highly fated with the [aline principle ? Some 

 mixture of Earth and Sulphur 'tis true there is in them, which 

 give the opacity that moft ftones have ; from which, according as 



Dell Hi[l. Natural. M.2J. cap. 8. 



they 



