z6t A SYSTEM OF 



SECT. CCXCIV. 

 The THIRD ORDER, 



NATURAL SLAGS, 



Scoria Vulcanorum, 



Slags arc found in great abundance in many 

 places in the world, not only where volcanos 

 Vet exift, but likewife where no fubterrane- 

 ous fire is now known : Yet, according to our 

 opinion, they cannot be produced but by means 

 of fire. Thefe are not properly to be called natu- 

 ral, fince they have marks of violence, and of the 

 laft change that mineral bodies can fuffer without 

 the deftru6tion of the world •, nor are they artificial, 

 according to the univerfally received meaning of 

 this word. When we perhaps in future times by 

 new difcovered means may be able to find out of 

 what fort of earth (tones are compounded, we 

 i'hall ftill be forced to flop at the furface of them, 

 and be contented with knowing that they contain 

 a little iron. Mean while I cannot omit them 

 here, fince I have confidered the petrefactions •, 

 and therefore I will enumerate fome of them, ac- 

 cording to their external marks. 



contain more or lefs of this phlogifton. I have ranked them 

 in this place, that they might not be totally excluded. They 

 are elfe a medium unie?is between all the three kingdoms of 

 nature : And it may reafonably be afked, if all forts of earth 

 do not in form of very minute particles enter into the compo- 

 sition of vegetables and animals, after which they exift for 

 fome time in fcrm of mould, until the phlogiilon is again 

 ft para ted. 



SEC T. 



