A STSTgM OF 
SECT, ccxcm 
The THIRD ORDER, 
NATURAL SJ.AGS, 
Scoria Fulcanorum. 
Slags are fotind in great abundance in -many 
places in the world, not only where volcanos 
yet cxift, 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 
iaft change that mineral bodies can fuffer without 
the deftrudion 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 ftones are compounded, we 
Iball fldll be forced to ftc^ 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 petrefadions ; 
and therefore I will enumerate fome of them, ac- 
tording to their external marks. 
contain more or lefs of this phlogiflon. J have ranked them 
JO ibis place., that they might not be totally excluded. They 
are -.etfe a medium uniens between all the three kingdoms of 
aratare : And it may reafonably be alked, if all forts of earth 
do not in form of very minute particles enter into the compo- 
fition of vegetables and animals, after which they exift for 
Came time in form of mould, until the phlogillon is again 
kparatt'd» 
SECT. 
