136 
CAPTAIN NOBLE AND ME. F. A. ABEL ON FIEED GUNPOWDER. 
so taken, we have 
Total work= w(1 ~ - ^ M (35) 
= 332,128 gramme-metres per gramme of powder 
(486 foot-tons per lb. of powder). 
Bunsen and Schischkoff’s estimate of the work which powder is capable of performing- 
on a projectile, if indefinitely expanded, we have already given ; but their estimate (being 
only the fifth part of that at which we have arrived) is altogether erroneous, as these 
eminent chemists appear to have overlooked the important part which the non-gaseous 
portion of the charge plays in expansion. 
It is interesting to compare the above work of gunpowder with the total theoretic 
work of 1 gramme of coal, which is about 3,400,000 gramme-units. The work stored 
up in one gramme of coal is therefore more than ten times as great as that stored up 
in 1 gramme of powder. 
The powder, it is true, contains all the oxygen necessary for its own combustion, while 
the coal draws nearly 3 grammes of oxygen from the air. Even allowing, however, 
for this, there is a considerable inferiority in the work done by gunpowder, which is 
doubtless in part due to the fact that the coal finds its oxygen already in the form of 
gas, while a considerable amount of work is expended by the gunpowder in placing its 
oxygen in a similar condition. 
In an economic point of view also the oxygen stored up in the gunpowder is of no im- 
portance, as that consumed by coal costs nothing, while the oxygen in the powder is in a 
most expensive form. The fact is perhaps worth noting as demonstrating the impracticabi- 
lity of making economic engines deriving their motive power from the force of gunpowder. 
Z. SUMMARY OF RESULTS. 
It only now remains to summarize the principal results at which we have arrived in 
the course of our researches (a) when gunpowder is fired in a space entirely confined ; 
( b ) when it is suffered to expand in the bore of a gun. 
(a) The results when powder is fired in a close space are as follow, and for convenience 
are computed upon 1 gramme of powder occupying a volume of 1 cub. centim. : — 
1. On explosion, the products of combustion consist of about 57 per cent, by weight 
of matter, which ultimately assumes the solid form, and 43 per cent, by weight of perma- 
nent gases. 
2. At the moment of explosion, the fluid products of combustion, doubtless in a very 
finely divided state, occupy a volume of about - 6 cub. centim. 
3. At the same instant the permanent gases occupy a volume of *4 cub. centim., so 
that both the fluid and gaseous matter are of approximately the same specific gravity. 
4. The permanent gases generated by the explosion of a gramme of powder are such 
that, at 0°C. and 760 millims. barometric pressure, they occupy about 280 cub. centims., 
and therefore about 280 times the volume of the original powder. 
5. The chemical constituents of the solid products are exhibited in Tables III. & VI. 
6. The composition of the permanent gases is shown in the same Tables. 
