250 F.A. P. Barnard on the Explosive Force of Gunpowder. 
combustion would yary somewhat from those here detailed, but 
not to such an extent as very materially to affect the calculations 
which follow. 
In the experiments of the Heidelberg investigators, the gun- 
powder was burned under the ordinary pressure of the atmo- 
sphere. It may be objected that, in the chamber of a gun, other 
forms of combination of the elements may take place; but, 
though this is possible, it is hardly supposable that greater power 
would in such a case be developed. A combustion which should 
produce a greater volume of gas would probably be attended 
with a less development of heat; so that as much as woul 
ained in elastic force by one of these circumstances would be 
ost by the other. 
The specific gravity of the fixed residuum at 18° C. was found 
to be 2°35. Bya 
equal to 3340° C. 
'Nhe snecific heat at ~ 
e. > 
poapechively, 0:07672 and 0:05520. Their quotient is 1:39, which 
is the value of the thermo-dynamic index. . 
berated 
In order to find the original bulk of the gases, or the 
tude of the space within which they are compressed if h 
without expansion, we consider that the bulk of the powder be- 
fore combustion will be expressed in cubic centimetres by % > 
a cubic centimetre of pure water at maximum density weighing 
"one gramme, and W, being expressed in grammes. In like 
