CAPTAIN NOBLE AND ME. F. A. ABEL ON FIBED GUNPOWDER. 
89 
pebble generated respectively 275"4, 273-7, and 277-9 cub. centims., or a mean of 
2 75 ’68 cub. centims., at the above temperature and pressure .- 
From the combustion of a similar quantity of E,. L. G. powder resulted 106,080-4, 
103,676-5, and 104,606-7 cub. centims., or 274-7, 268-45, and 270*86 cub. centims. of 
gas (mean=271*34 cub. centims.) per gramme of powder; while 99,694-9, 101,372-3, 
99,164-8, and 100,289-0, or 262-4, 258-1, 256-8, and 259-68 (mean 259-2) cub. centims. 
per gramme were yielded by the F. G. powder. 
The difference in quantity of gas between the pebble and the R. L. G. is very 
slight ; but there appears to be a decided difference in the quantity generated by F. G. 
powder, the defect being much greater than can be accounted for by any errors of 
observation. 
The results of those experiments show that the quantity of permanent gases generated 
by 1 gramme of the service pebble or It. L. G. powders is about 276 cub. centims. at 0° C. 
and 760 millims. — that is, they occupy at this temperature and pressure about 276 
times the volume of the unexploded powder. 
The volume given off by F. G. is less, being about 260 volumes; and, if we may trust 
to the single measurement we have made of the permanent gases of It. F. G. (in 
experiment 80), the volume generated by this powder does not differ greatly from that 
given off by F. G. 
With the view of ascertaining whether a powder of a marked difference in composition, 
such as the Spanish spherical pellet powder, gave the same quantity of permanent gases 
as our service-powders, a measurement of the volume generated by this powder was made 
(in experiment 81). 
The quantity was found to be notably less, being only 232-7 volumes; but this 
measurement was the result of one determination only. 
H. RESULTS OF EXPLOSION, DEDUCED BY CALCULATION FROM ANALYTICAL DATA. 
We are now in a position to apply two important tests to the results at which we 
have arrived as regards composition of products and measurement of gases. From a 
consideration of the analysis of the solid products of explosion, we are able to deduce 
the total weight of the solid residue, and thence, by difference, the weight of the 
gaseous products. On the other hand, from a consideration of the measurement of the 
volume of the gaseous products, combined with their analysis, we can calculate the 
weight of the gaseous and, by difference, that of the solid products ; and if these 
calculations accord, a valuable corroboration of the accuracy of our results will be 
obtained. We can also compare the amounts of the elementary substances in the 
powder before and after combustion, and so obtain a still further corroboration of 
accuracy. 
We have applied these tests to all the analyses completed; and we proceed to give 
two illustrations of the method — one applied to pebble, the other to F. G. powder. 
In experiment 12, 411-085 grms. pebble powder were fired, and the products of 
combustion collected and analyzed. The analysis of this powder has been already 
MDCCCLXXV. N 
