F. A. P. Barnard on the Explosive Force of Gunpowder. 249 
And v=o 15-4408” J drei joa 
Calon ari 
y2 c? 2-4n gyi 
NO P= Sages eo ee 
If the value of v last found be divided by that obtained pre- 
viously, the ratio is Jee, which, when the powder is half 
the weight of the shot, is =0°9661; showing that the velocity 
obtained by the method we have just been considering, is not, 
eveu with so excessive a charge, three and a half per cent less 
than that deduced from the empirical allowance of one-third the 
weight of the charge to the weight of the projectile. That allow- 
ance is therefore nearly correct. When n is put =0, or the 
weight of the powder disregarded, the two determinations agree, 
as they ought. 
We will now attend for a moment to the method of deducing 
the value of p, a priori. 
The materials employed in the manufacture of gunpowder, 
are mixed nearly in the proportion of one equivalent of salt- 
a one equivalent of sulphur, and three equivalents of car- 
n. If, in the combustion, the sulphur and potassium be sup- 
osed to combine, we may assume the results to consist of one 
