212 
CAPTAIN NOBLE AND MR, F. A. ABEL ON FIRED GUNPOWDER. 
residues is not sufficient to account for all but the very small quantities of hypo¬ 
sulphite which M. Berthelot considers could only have pre-existed in the residue 
examined by us. That chemist appears, moreover, to have overlooked the following 
facts given by us in our first memoir 
1. Separate examinations (conducted precisely alike) of the upper and lower portions 
of some of the residues showed that considerably larger proportions of hyposulphite 
existed in the upper portions. In one case quoted by us in our first memoir, the 
upper portion contained 17T4 per cent, of hyposulphite, while the lower portion only 
contained 4\34 per cent. At the same time there was only a difference of 1 *27 per 
cent, in the proportions of monosulphide existing in the two portions of the residue 
(6'03 in the upper part, and 7'3 in the lower), while there was a very great difference 
in the amount of free sulphur (4'88 in the upper part, and 10'09 in the lower). 
2. One of the small buttons of the fired solid products, of which there was generally 
one found attached to the firing plug in the cylinder, was examined for sulphide and 
hyposulphite (it having been detached without fracture, and at once sealed up in a 
small tube). It contained the latter, but none of the former, while the mass of the 
residue of this particular experiment contained a somewhat considerable proportion 
of sulphide. 
3. The production of high proportions of hyposulphite was but little affected by 
any variations in the circumstances attending the several explosions (i.e., whether the 
spaces in which the powder was exploded were great or small), excepting that the 
amount was high in all three cases when the powder was exploded in the largest space. 
On the other hand, a great reduction in the size of grain of the gunpowder used 
appeared to have a great influence upon the production of hyposulphite, as when 
passing from a very large grain powder (pebble or B. L. G.) to a fine grain powder (F. G.). 
Thus the production of hyposulphite exceeded 20 per cent, in — 
3 experiments out of 9 with pebble powder (Nos. 8, 38, 43). 
3 „ „ 10 „ B. L. G. „ (Nos. 1, 11, 70). 
7 „ 9 „ F. G. „ (Nos. 16, 18, 19, 40, 42, 47, 69). 
It was below 10 per cent, in— 
4 experiments out of 9 with pebble powder (Nos. 7, 9, 11, 37). 
5 „ „ 10 „ B. L. G. „ (Nos. 3, 39, 44, 68, 96). 
1 „ 9 „ F. G. „ (No. 17). 
There were no circumstances connected with the carrying out of the explosions, or 
with the collection and analysis of the residues, to which the above great differences 
between the results furnished by fine grain powder and by the two large grain powders 
could be ascribed. 
While, however, certain of the great variations in the proportions of hyposulphite 
and sulphide, which cannot be accounted for by variations of structure of the residue 
