CAPTAIN NOBLE AND MR. F. A. ABEL ON FIRED GUNPOWDER. 
227 
powder, for example, generates just 50 per cent, more heat than the mining powder) : 
and, secondly, that the heat evolved by the same description of powder varies in 
different experiments to a greater extent than is to be accounted for by errors of 
observation. And this was, indeed, to be expected, since the very considerable varia¬ 
tions in the products of combustion, under the same circumstances, as disclosed by our 
analyses, could hardly be supposed to exist without some corresponding variation in 
the heat evolved. 
Our views on this head are confirmed by the calorimetric determinations we have 
made in our researches on gun-cotton. In these determinations, which have been 
carried on with precisely the same apparatus, we have found no appreciable difference 
in the heat evolved in the various experiments. The deduction is that the discrepancies 
between the several observations in the case of gunpowder are due to differences in the 
metamorphoses, not to defects in the observations. 
The units of heat liberated given above are those furnished by the powders as 
actually used ; but as these powders had different amounts of moisture in their com¬ 
position, and as, in use, these amounts of moisture are found to vary considerably, 
giving rise, especially when the powders are used in guns, to very different pressures, 
and generating very different energies, we have considered it desirable to correct the 
above figures, and we place below those that would have had place had the powders, 
when fired, been perfectly free from moisture. 
Table Y.— Showing the heat, in gramme-units, generated by the combustion of 
1 gramme of the undermentioned perfectly dry powders. 
1 gramme 
pebble powder 
generates 
721-4 
gramme-units. 
1 „ 
VV. A. R. L. G. powder 
33 
725-7 
3 3 
1 „ 
W. A. F. G. powder 
33 
738-3 
33 
1 „ 
C. and H. No. 6 powxler 
33 
764-4 
33 
1 „ 
mining powder 
33 
516-8 
33 
1 
Spanish pellet powder . 
33 
767-3 
33 
The data for computing the mean specific heats of the products of explosion of the 
six powders, as well as the results of the necessary calculations, are given in the 
annexed Table, No. YI. 
2 G 2 
