THE HISTORY OE EXPLOSIVE AGENTS. 
391 
packages, were placed upon tables in a light wooden building (8 - 5 feet square by G‘5 
feet high), and a heap of inflammable material was placed between the tables. It was 
somewhat difficult to determine the precise time after the fire was first kindled in the 
building when the dynamite commenced burning, as the change in the appearance of 
the flame was less characteristic or sudden than with gun-cotton as observed from a 
distance. The rapidly increasing fierceness of the flame, however, about five minutes 
after the fire was kindled, showed that the nitroglycerine was burning ; and after the 
lapse of ten minutes a violent explosion occurred, fragments of the wooden structure 
were thrown to great distances, and a large crater was formed in the ground. 
These experiments, conducted with 672 lb. of gun-cotton and with 500 lb. of nitro- 
glycerine in the form of dynamite, placed in confined spaces, demonstrated that if some 
portion of the explosive substance is ignited, the remainder of the material being pretty 
strongly confined, the very rapid increase in the intensity of the heat developed may 
soon combine to raise some portion of the still confined explosive to the inflaming 
point, and that then, the mass being already in a heated condition, the inflammation 
may proceed with such rapidity as to develop the pressure essential for establishing 
explosion while the substance is confined, which explosion would be instantaneously 
transmitted to the contents of the surrounding packages. It was also satisfactorily 
demonstrated that with equal quantities of explosive material confined in packages, a 
difference in the strength of confinement of the substance is productive of an important 
difference when the material is exposed to fire. The weaker the packages the more 
readily they are opened up by pressure from within ; hence, when some portion of the 
contents of a box of light structure becomes raised to the inflaming-point, the pressure 
developed by the ignition is not sustained to a sufficient extent or for a sufficient time 
to bring about explosion. It need, however, be scarcely pointed out that the safeguard 
against explosion thus presented, in the case of compressed gun-cotton or of a nitro- 
glycerine preparation, by the employment of packages of light structure, must be limited 
by the guantity of explosive material exposed to fire. Thus it is very probable that, 
although no explosion resulted from the exposure to fire and ultimate burning of 
6 cwt. of gun-cotton contained in packages of light structure, while explosion was pro- 
duced in experimenting with a similar quantity in strong packages, the difference, in 
the strength of the boxes might not have ensured safety against explosion with a much 
larger quantity. Indeed it may be presumed that, if the quantity be sufficient, no 
further confinement than that afforded by the outer portions of a large pile of disks of 
compressed gun-cotton, or cartridges of dynamite, would be required, after the burning 
had proceeded for a sufficient time, for determining the explosion of some portion of 
the interior of the mass, in consequence of the resistance opposed to the escape of gas 
from the confined or inner portions to which the fire had reached. 
The results furnished by the experiments just described were similar in their character, 
and the conditions which determined them, to those noticed on the occasion of the 
accident at the Stowmarket Gun-cotton Works in August 1871. The ignition of some 
