86 
CAPTAIN NOBLE AND MR. F. A. ABEL ON FIRED GUNPOWDER. 
size and form of the grains or individual masses, &c.). Hence it is not surprising to 
find that a fine-grain gunpowder, which differs much more in mechanical than in che- 
mical points from the larger powder (R. L. G.) used in these experiments, should present 
decided differences, not only in regard to the pressures which it develops under similar 
conditions, but also as regards the proportions and uniformity of the products which 
its explosion furnishes. On the other hand, the differences in regard to size of in- 
dividual masses and other mechanical peculiarities between the R. L. G. and pebble 
powders are, comparatively, not so considerable, and are in directions much less likely 
to affect the results obtained by explosions in perfectly closed spaces. 
Again, the analysis of solid residues furnished by different kinds of gunpowder which 
presented marked differences in composition, did not establish points of difference which 
could be traced to any influence exerted by such variations ; indeed the proportions of 
the several products composing residues which were furnished by one and the same 
powder, in distinct experiments made at different pressures, differed in several instances 
quite as greatly as those found in some of the residues of different powders which pre- 
sented decided differences in composition. This will be seen on comparing with each 
other the analysis of certain residues of P. powder (e.g. experiments 7 and 12), of 
R. L. G. powder (e.g. experiments 4 and 39), and of F. G. powder (experiments 17 
and 42), and on then comparing the composition of the residues of F. G. and R. F. G. 
obtained in experiments Tl and 18. 
"When, however, the deviation from the normal composition of cannon-powder is 
comparatively great, a decided influence is thereby exerted upon the proportions in 
which the products of explosion are formed. Thus, in the Spanish pebble powder 
specially selected by us for experiment on account of the considerable difference between 
its composition and that of the English powders, the proportion which the saltpetre 
bears to the carbon is comparatively high, while the amount of sulphur it contains is 
very high. An examination of the gaseous products which it furnished shows that 
the proportion of carbonic oxide is only one half the amount produced under precisely 
the same conditions, as regards pressure, by R. F. G. powder, and about one third 
the amount contained in the products furnished by pebble and R. L. G. powders under 
nearly similar conditions. With respect to the solid products of explosion obtained 
with the Spanish powder, they also present several points of great difference from the 
products furnished by the powders of English manufacture. The amount of potassium 
carbonate is very much lower than in any of the other residues examined, and the 
sulphate very much exceeds in amount the largest proportion furnished by the English 
powders. The proportion of sulphide is small, while that of hyposulphite is also not 
considerable. 
Although, for the reasons given in the foregoing, we cannot attempt to offer any 
hardness of the individual grains or masses, the composition of the powder remaining unaltered. The Com- 
mittee on Explosive Substances have adhered to this system in producing gunpowder suitable for the largest 
ordnance of the present day. 
