MINERALOGY* 2711 
furnaces decay, and at lafl: produce vegetables^ 
which cannot be afcribed to a black mould alone 
carried thither by the wind. The larne may per- 
haps happen with the natural flags in the open air 5 
but we do not know if it is fo, nor what different 
forms this and every other earth which circulate^ 
in animals and vegetables further aflumes : How- 
ever, in fuch circumftantes, as their particles be- 
come or are already very minute, afid moft part of 
the phlogiflon becomes volatile, when a6led upon 
by heat or fire, it feems probable, that, by a flow 
reparation of the phlogiflon, or a union by means 
of faks, this earth is mofl apt to become a clay, 
provided it is not by any previous revolution laid 
in fuch places as to change it into flate, pit-coal, 
&c. 
If at any time it fhould happen that a volcano 
fhould biirfl out o£ a niiountain, whole flrata wc 
knew before, we could at leak imagine fome rea- 
fonsfor this wonderful effed : However, the learned 
would neverthelefs, perhaps, want fome knowledge 
about the fubkances of the flrata, and the manner 
of their formation ; fmce in this circumflance water 
and other obflacies have hindered people too much 
from making the due obfervations thereon. 
MeanwhRe, the rftore we confider, on the one 
part, all the modifications* and alterations the earths 
undergo by means of fire' and water, by the free 
or impeded accefs of the^air, by the volatility and 
attradion of the acid faits, whereby are pro- 
duced folution and hardening, compofition and 
reparation ; and, on the other part, reflefl on the 
fliortnefs of a man’s life, perhaps alfo dedicated to 
other bufmefs, on the difficulty of obferving the 
fubterraneous efteds, and on feveral other things, 
which prevent the making difcoveries, by which 
we might find out fome eafier means to attain true 
knowledge 
