4. A charge of blasting gelatine, inserted in one of Settle's water
cartridges, was suspended in the boiler tube and fired with a
fulminate of mercury detonator in the usual manner. The gelatine did
not, however, explode, the only report being that of the detonator.
After a safe interval the unexploded cartridge was recovered, or so
much of it as had not been scattered by the detonator, and the
gelatine was found to be frozen. This fact was also evident from an
inspection of other gelatine dynamite cartridges which had been stored
in the same magazine during the night. This result, although not that
intended, was most instructive as regards the danger of using
explosives which are liable to freeze at such a moderate temperature,
and the thawing of which is undoubtedly attended with great risk
unless most carefully performed. Also, the small pieces of the
gelatine or dynamite, when scattered by the explosion of the
detonator, might cause serious accident if trodden upon.--_Engineering._
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