its wenderful EffeBs. 7 3 
Death : and animal dead Bodies frozen be¬ 
come as hard as Stone. Hence it appears, 
that freezing is not the Refult merely of the 
Abfence of Heat, but is really owing to 
fome adlive and penetrating material Prin¬ 
ciples, which by mixing with other Bodies 
become thereby fixt: and the Exiftence of 
fuch Principles in the Air is farther appa¬ 
rent from the rafting of Metals, the E rollon 
of Stone, Glafs, &c. 
The Soppofition that Salt-Petre is com¬ 
pounded in a great Meafure of this fame vola¬ 
tile acid Spirit exifting in the Air, is ftrength- 
ened, not only by the Manner of its Pro¬ 
duction, but alio from its ftriking the 
Tongue, when tafted, with a pungent Sen- 
fation of Cold, like what this fame Spirit 
in the Air giyes : Moreover, a volatile acid 
Spirit may be obtained from it in conlider- 
able Quantity, whofe Particles are fo adtive 
and powerful, that they penetrate, disjoin, 
and feparate the component Particles of all 
Metals except Gold, as well as Stones and 
moll; other Bodies. 
Suppofing fuch Spirit one of the chief 
Principles of Salt-Petre , may not its exceed¬ 
ing Volatility, when fuddenly and violent¬ 
ly excited to Adtion, by the Fire contained 
in Sulphur kindled by Charcoal, produce all 
the prodigious EfFedts of Gunpowder * ? 
9 yide Queries, p. 2 60 
and 
