C 454 ] 
of Grains that had been fired, but were extinguished 
by the Blaft before they were intirely confumed. 
This Conje&ure is ftrengthened by the extreme Mi- 
nutenefs of the Particles of all the Powder which was 
collected, and from the Deficiency of the Saltpetre 
found in it on Examination : It may be added too, 
that the Author, by gradually heating a Parcel of 
Powder, hath fet it on Fire, and blown it out again, 
for at leaft a Dozen times fucceflively j and he will 
undertake to repeat the Experiment at any time, if it 
Should be doubted of. 
The Poftulates hitherto difeuffed are preparatory 
to the 7th Propofition. That Propofition is em- 
ployed in computing the Velocity which would be 
communicated to a Bullet in a given Piece by a given 
Charge of Powder, on the Principles hitherto laid 
down, that is, fuppofmg the Elafticity of fired Pow- 
der to be at firft 1000 times greater than that of 
common Air. 
In the 9th Propofition thefe Computations are 
compared with a great Number of Experiments, 
made in Barrels of various Lengths, from Seven 
Inches to Forty-five Inches, and with different 
Quantities of Powder, from 6 dwt. to 3 6 ; and 
the Coincidence between the Theory and thefe Ex- 
periments is very Singular, and fuch as occurs in but 
few philofophical Subjects of fo complicated a 
Nature. 
By this Agreement between the Theory and the 
Experiments, each Part of the Theory is feparately 
confirmed; for by firing different Quantities of 
Powder in the fame Piece, and in the fame Cavity, 
it appears that the Velocities of the Bullet, thence 
