216 
CAPTAIN NOBLE AND MR. F. A. ABEL ON FIRED GUNPOWDER. 
It will be seen from the foregoing numerical results that in both experiments those 
portions of the residue which were exposed to the air only for a few seconds, and of 
which only small surfaces were thus exposed (as they were collected in large lumps), 
contained hyposulphite ranging in amount from 5 to 8’5 per cent. Those portions 
which were specially treated for the purpose of favouring to the utmost the formation 
of hyposulphite from sulphide through atmospheric agency, contained, as was to be 
expected, very large proportions of the former, while the latter had entirely disap¬ 
peared in three out of the four portions of very finely pulverised residue. In the 
fourth, however, even after its free exposure to air for forty-eight hours, there still 
remained nearly 3 per cent, of sulphide. Now, as in no single instance in the entire 
series of our experiments did any accidental circumstances occur which even distantly 
approached the special conditions favourable to the oxidation of the sulphide which 
were introduced into these particular experiments, we consider ourselves justified in 
arriving at the conclusion that the total absence of sulphide in the residues furnished 
by the fine grain powder in experiments 40, 42, and 47 was not due to accident in the 
manipulations, and that in those residues in our series of analyses which were found 
to contain large quantities of hyposulphite (as in six out of the nineteen experiments 
with pebble and It. L. G. powder, and eight out of the nine with F. G. powder) a 
great proportion, at any rate, of that hyposulphite existed in those particular resi¬ 
dues before their removal from the explosion-vessel. The circumstance that the residues 
furnished by our two most recent experiments (with sporting powder and mining 
powder), in the treatment of which the possibility of accidental formation of hypo¬ 
sulphite was altogether guarded against, contained 4, and about 6, per cent, of hypo¬ 
sulphite, demonstrates that even under these conditions a very notable quantity of 
that substance is found in powder-residue ; but it cannot, we consider, be taken to 
support the view that, in a residue containing a much higher proportion of hyposulphite, 
the existence of the whole or a large part of that excess is ascribable to accident of 
manipulation. In the series of experiments with pebble powder there were three, in 
that with R, L. G. powder four, while in that with F. G. powder there was one, of 
which the residues contained proportions closely similar to those furnished by the two 
experiments above quoted, there being no peculiarity in those seven experiments nor 
any attendant circumstances which could be assigned as a possible reason why the 
proportions of hyposulphite in those cases should be so much lower than in the other 
experiments with the same powders, carried out under the same conditions. We 
therefore cannot but conclude that the production of a small or of a large proportion 
of hyposulphite (whether as a primary or secondary product, but before the explosion- 
vessel is opened) is determined by some slight modification of the conditions attending 
the explosion itself 
From an examination of the proportions of potassium sulphate found in the different 
parts of the two residues, it will be seen that in the case of the It. L. G. there was a 
