once an Experimental proof, that either the Saline j'teams , 
which afccnd from a heap of Salt , do pierce through very 
thick ftone- walls Or (which I did much rather conceive5)they 
generate more Salt 5 toa greatdepth of thicknefs, in the Lime 
and Mortar of the Walls. 
2 Dr Fewer in his Mkrcfc, 0kf,p4g, 62. a0iires from good 
Teftimony, and common experience, that a Mineral heat in 
the Subterraneous parts produceth Minerals: A nd particularly , 
that in Allum and Coperas-raines , thofe Minerals being bro- 
kcn^expofed^and moiftened; will gather an adual heat 5 and pro- 
duce much more of thefe Minerals 3 thanelfe the Mine would 
yield. And there he further proves by an unlucky accident, 
that BrafiTe-lumpSj f which he faith is a kind of Marcafitej)being 
!ayd in heaps and expof^^d to the moift Air , or fprinkled with 
water p will fmoak , and grow exceeding hot 5 and fome-. 
tirres talce fire, and burn all that is about them. Thus y^^.And 
all forts of Dung afford a Heate , fome lefs , and fome ftronger; 
fome fpeedily, and fome more permanently . And ftoreof Ni- 
tremay be had from the fweepings of the houfe, any kind ( f 
aihes, (hovelingsofany fordid place ^ the cleanfings from the 
back ftayrs,and emptying of the Chamber-pots, if alwayscaft as 
firatum faper (tratum in a dry Well, or Vault, only fo cove- 
red and fenced, that the Rain and water gets not in. Dr Pcmr 
fliews here,How Metals or Minerals may be generated 5 but how 
far this Generative force will run , and from what Bulke of Ma- 
terials 5 and what Materials are apteft to be transformed into 
what Minerals or Meta s^we muft refer to further tryal. Of this 
we are certain , that by a ftrong Fire^thus raifed by Brafs-lurops, 
Stones and Metals may be vitrified, and thence afiume another 
Natore. and Luftre than is ordinary • And by the Gentler heats, 
( befides the acqueft of Salt-peter in the end ) there may be Me- 
chanical applications peculiar for the Gradual and flow produ6ii- 
ons of Chymiftryjtothfor iiaturaleffc(3s upon ufual Proximi- 
ties, and for Artificial Contrivances. 
3. In your i\r^^.6.p, loi.youfliew uSjthat there a Is place in 
£;jg/W,where,without petrifying water ^ wood is turned into 
ftone 5 in a Sandy Earth. But can we yet fay 5 whether Vaults 
digged in fuch Grounds may not have a Petrifying .5'pirit ^ as 
there 
