new inflammable Air or Gafs , See. 395 
Mr. robins and Count saluce; but yet the evaluation 
of the two laft mentioned writers, though fhort of one 
half, proves in reality Mr. bernouilli’s calculations to 
be as juft as can be expected, when it is confidered, that 
this evaluation was made before the new difeoveries 
upon the nature of nitre and charcoal. But this affertion 
will be better underftood when I have explained the na- 
ture of gunpowder fomewhat fuller. 
If we continue to fay, as we have hitherto done, that 
the charcoal taking fire decompofes the nitre, and extri- 
cates from it that amazing quantity of elaftic fluid which 
was flout up within its' fubftance, we only fay what we 
fee in reality is the confequence of fetting fire to this in- 
gredient. But this explanation does not convey a clear 
idea of the manner in which the extrication is carried on; 
nor of the reafon why one Angle fpark of fire, thrown 
into an immenfe heap of gunpowder, fliould almoft in 
an inftant fpread the conflagration through the whole 
mafs. Neither does it explain clearly, why nitre and 
charcoal (which feparately yield no flame at all, though 
ever fo much heated) when combined and intimately 
mixed together, explode with as loud a report as a large 
ordnance piece, furpaffing even in loudnefs thunder- 
claps ; nor why this forcible explofion is accompanied by 
a molt brilliant flame. 
Nitre 
