CAPTAIN NOBLE AND ME. F. A. ABEL ON EIEED GUNPOWDER. 
93 
that it is not difficult to conceive causes which might tend to make the mean measured 
quantity of gas somewhat less than reality, while it is hardly possible that the reverse 
can be the case. 
For example, without doubt an appreciable quantity of gas is occluded, as indicated 
by the conditions of the residues (see account of experiments Nos. 10 and 38) and by 
the disengagement of gas generally observed upon addition of water to the residue. In 
some instances also there may be, under the high pressure of explosion, a trifling 
leakage from the apparatus. 
One point we must not pass over without observation. The deficiency of hydrogen 
in the products of explosion, although absolutely small, is relatively very large. The 
question then arises as to whether the missing hydrogen may not be present in the 
form of aqueous vapour. None was detected in the analysis of the gases ; but it is not 
difficult to explain this fact, as the extremely hygroscopic property of the residue would 
most effectually dry the gases — the absorption of the vapour by the residue being 
actually demonstrated by the greasiness observed on the surface of the deposit and on 
the sides of cylinder immediately on its being opened after explosion. The entire 
proportion of water formed or preexisting must therefore have existed in the solid 
residues, but its determination therein was obviously impracticable. 
The amount of water present can, however, be calculated from the deficiency of 
hydrogen shown in our Tables. 
I. CONDITION OF PRODUCTS AT THE INSTANT OF OR SHORTLY AFTER EXPLOSION. 
A careful examination of the contents of the cylinders after they were opened showed 
that, at all events shortly after explosion, the solid products were in a fluid state. It 
was of course impossible to open the cylinder while the solid products were still fluid ; 
but it occurred to us that we might yet obtain valuable information as to the state of 
the contents at different periods after the explosion. Accordingly, in experiment 40, 
the cylinder being about two thirds filled with F. G., thirty seconds after the explosion 
the vessel was tilted so as to make an angle of 45°. Two minutes later it was restored 
to its first position. 
On subsequent examination the deposit was found to be lying at the angle of 45°, and 
the edges of the deposit were perfectly sharp and well defined. 
In experiment 41, the cylinder, being about three fourths filled with 14. L. G., was 
allowed to rest for one minute after explosion. It was then placed sharply at an angle 
of 45°, and forty-five seconds later it was returned to its first position. 
Upon opening it was found that when the cylinder was tilted over the deposit had 
just commenced to congeal ; for upon the surface there had been a thin crust which the 
more fluid deposit underneath had broken through. The deposit was lying at an 
angle of 45°, but the crust through which the fluid had run was left standing like a 
thin sheet of ice. 
