CAPTAIN NOBLE AND MR. F. A. ABEL ON FIRED GUNPOWDER. 
213 
or of manipulations favourable to oxidation by atmospheric agency, appear to us to 
demonstrate that the hyposulphite is formed in the solid residue before the explosion- 
vessel is opened, and indeed in such amount that it must be regarded as an important 
product (whether it be a primary or a secondary one), we have been anxious to 
obtain, if possible, some more decisive evidence as to the probable proportions of 
hyposulphite actually existing in the residues furnished by the explosion of gun¬ 
powder in closed vessels. We therefore varied the method of collecting and pre¬ 
paring the residues for analysis, in the experiments of which the following is an 
account :— 
1. 5960 grains (38G - 2 grammes) of the It. L. G. and pebble powders used in these 
researches were fired in the large cylinder under a density of 0'40. 
Immediately on opening the cylinder in each case, the solid products were as nearly 
as possible divided into two equal portions, consisting of the top and the bottom. Each 
of these portions was again divided roughly into two equal parts, one of which, in 
large lumps, was, as rapidly as possible (being but for a few seconds exposed to the 
air), sealed in dry bottles freed, or nearly so, from oxygen, the other moieties being 
finely ground and freely exposed to the air for 48 hours. 
The only point of difference calling for remark in the appearance of the two residues 
was the difference in colour, the residue from the pebble being decidedly the lighter 
in colour, both on the surface and in fracture ; but there were material differences in 
the behaviour of the ground portions of the two powder residues. 
With both powders, the bottom ground portion heated very decidedly more than 
the top ; but while, in the Pi. L. G., this tendency was exhibited in a remarkably 
low degree, with the pebble the tendency to heat was, we think, abnormally high. In 
the latter case, the ground deposit from the top began to heat immediately on being 
placed upon paper. The deposit on the apex of the cone and in the interior, where 
the heat was highest, changed rapidly in colour to a light yellow, tinged with green. 
The ground bottom part of the residue darkened considerably during the develop¬ 
ment of heat, and an orange-coloured deposit was condensed on the surface. 
When the heat was highest, a considerable quantity of vapour was given off. Its 
smell was very peculiar; SIL w r as distinctly perceptible, but was by no means the 
dominant odour. 
The maximum temperature appeared to be reached at about twenty minutes after 
exposure. A thermometer placed in the centre indicated a temperature of over 600° F. 
(315° C.), and the paper on which the residue was placed was burnt through. After 
half an hour’s exposure the deposit cooled very rapidly. 
It should be observed that the physical characteristics of the ground deposit were 
altered very materially by the heating. When the residue is taken out of the 
exploding cylinder, it is difficult to pound in the mortar, being somewhat unctuous ; 
but after the development of heat it becomes crisp, and is readily powdered. 
2. In the examination that we have instituted of the products of explosion of a 
