94 
CAPTAIN NOBLE AND ME. E. A. ABEL ON EIEED GUNPOWDER. 
Hence in this experiment, one minute after explosion, the non-gaseous products had 
commenced to congeal, and forty-five seconds later they were solid. 
In experiment 77, the cylinder, being completely full of pebble powder and fired, 
was placed at an angle of 45° one minute after exptasion, and the position of the 
cylinder was altered every fifteen seconds. It was found that at sixty and seventy-five 
seconds after explosion the deposit was perfectly fluid, the evidence of each motion 
of the cylinder being given by a wave of deposit. At ninety seconds it was rather 
viscid ; at one hundred and five seconds the deposit hardly moved. 
Hence in this experiment it was rather more than a minute and three quarters before 
the non-gaseous products became solid ; and the conclusion from the experiments is 
that, very shortly after explosion, the non-gaseous products are collected as a fluid at 
the bottom of the exploding-vessel, and that some time elapses before these products 
finally assume the solid form. 
J. THE POSSIBILITY OE DISSOCIATION AMONG GASEOUS PRODUCTS CONSIDERED. 
In the attempt to reconcile or account for the discordant estimates of the pressure 
exerted by fired gunpowder, some authorities have supposed that the phenomena con- 
nected with dissociation play an important part, and that, for example, the dissociation 
of carbonic anhydride into carbonic oxide and oxygen may give rise to a considerable 
increment of pressure. 
Berthelot has enunciated the view that the tendency to dissociation at very high 
temperatures possessed by compound gases operates in preventing the formation, at 
the time of explosion, of certain of the constituents which exist in the ultimate gaseous 
products, and that during the expansion in the bore of the gun and the concomitant 
fall of temperature, the compound gases existing in those ultimate products are gra- 
dually formed. He*, indeed, points out that the effects of dissociation must not be 
exaggerated, and that the decomposing influence of high temperature in the case of an 
explosion may be altogether or in part compensated by the inverse influence of pressure. 
Having given this subject our careful consideration, we cannot even go so far as Ber- 
thelot does in accepting the view that the results of explosion. of powder in a gun are 
at all affected by dissociation, the occurrence of which we cannot consider probable even 
when the pressure to which the gases are subjected in the bore of a gun is relieved to 
the maximum extent. 
It is perhaps, however, worth while examining what would be the effect on the 
pressure if the particular case of dissociation to which we have alluded above actually 
occurred. 
Among the products of combustion of 1 gramme of powder is -28 grm. of C0 2 occu- 
pying, at 0° C. and 760 millims. pressure, 142 cub. centims. ; now if we suppose this 
C0 2 dissociated into CO and O, the 142 cub. centims. of C0 2 would become 213 cub. 
* Berthelot, 1 Eorcede la Poudre &c.,’ 1872, p. 81. 
