74 Properties of Nitre* 
and alfo by certain Mixtures in the Air, 
become the Caufe of Thunder, Lightning, 
and other wonderful Phenomena ? 
The foregoing Conjectures, into which 
I fear I have been led too far by my Sub¬ 
ject, may it is hoped be forgiven, as they 
are fubmitted entirely to the Condderation 
of better Judges, without the lead Dedgn 
of impofmg them on any one.—But to re¬ 
turn to the known Properties of Salt - 
Petre. 
It is faid to be the only Didol vent of Sil¬ 
ver, as Sea-Salt is of Gold : for Silver is dif- 
folveable in no Menitruum yet known, 
unlefs there be Nitre in it ; and yet if Salt 
be added thereto, the Mixture will no 
longer diffolve Silver but Gold. It pre* 
ferves the Flelh of Animals from Putre¬ 
faction as well as Sea-Salt, and has the lin¬ 
gular Property of giving it a red Colour 
In Biftiliation alfo, the fumes that arile 
from Nitre are red. 
* The Roots of Madder mixed with the Food of Animals 
tinges their Bones of a curious Red. Vide Philofoph. ’Tranf. 
N° 442, and 443, where Experiments in Proof thereof are 
given by Mr. Belcher, F. R. S. The fame is likewife con¬ 
firmed N° 457, by farther Experiments made by MonJ A 
JQji Hamel du Monceau. 
C H A P. 
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