[ 239 3 
•which frequently retain the qualities of the denfe bo- 
•dies from which they were generated ; and which, 
by being reduced to an elaftic ftate, become more 
a^ive and penetrating, and operate much more fud- 
denly and violently upon the human body; as the 
fumes of quickhlver, and the vapour of water, by 
their effedts, do fufficiently prove. 
Now, as thefe fubtile and elaftic fpirits do fre- 
quently exert very fudden and violent effedls upon 
the human body ; and entering the compofition of 
mineral waters, often endow them with excellent 
virtues ; it may, therefore, be ufeful to examine the 
origin of thofe fpirits which are found in fountains, 
and to conlider in what manner water becomes im- 
pregnated with them as it pafTes through the bowels 
of the earth. To determine which queftions, thofe 
obfervations will greatly contribute, which we have 
already given concerning the generation of the fire- 
damp, and its lodgment in the cavities of earth. For 
as the fire-damp is generated from fulphureous and 
ferruginous fubfiances, and is often clofely pent up* 
with water, and intimately (5) blended therewith in the 
fubterraneous cavities ; its particles, therefore, being 
impelled by their own elaftic prelTure into the pores 
of the water, will be diflblved therein, after the fame 
manner as 1 have before fiiewn they may be diflblved 
therein by art. And in like manner, water will be- 
come impregnated with thofe other kinds of air and 
mineral exhalations, which are lodged in the fubter- 
raneous cavities thro’ which it palfes. The fubter- 
raneal damps and mineral fpirit of fountains feem, 
(5"^ See ElPay on the Fulminating- damp, 
therefore, 
