ocities and more regular pressure in the gun, and lower temperature.

Cordite of either mark is a perfectly waterproof substance, containing
only traces of water remaining from the manufacturing processes. It has
a density of about 1.56 at the ordinary temperature (15 deg. C.), and, as
its coefficient of expansion is small, this density does not change to
any serious extent under climatic temperature variations. A rod may be
bent to a moderate extent without breaking, and Cordite M.D. especially
shows considerable elasticity. It can be impressed by the nail and cut
with a knife, but is not in the least sticky, nor does the
nitro-glycerin exude to any appreciable extent. It can be obtained in a
finely-divided state by scraping with a sharp knife, or on a new file,
or by grinding in a mill, such as a coffee-mill, but can scarcely be
pounded in a mortar. Cordite is of a brownish colour in mass, but is
much paler when finely ground or scraped. The rods easily become
electrified by gentle friction with a dry substance. Like all colloidal
substances it is an exceedingly bad conductor of heat. A piece ignited
in air burns with a yellowish flame. With the smaller sizes, about 2 mm.
diameter or less, this flame may be blown out, and the rod will continue
to burn in a suppressed manner without actual flame, fumes containing
oxides of nitrogen being emitted. Temperature appears to have an effect
on the rate of burning. When much cooled it certainly burns more slowly
than when at the ordinary air temperature, and is also more difficult to
ignite. Rods of moderate thickness, say from 5 mm. diameter, will
continue to burn under water if first ignited in air and the burning
portion slowly immersed. The end of a rod of cordite may be struck a
moderately heavy blow on an anvil without exploding or igniting. The rod
will first flatten out. A _sharp_ blow will then detonate or explode
the portion immediately under the hammer, the remainder of the rod
remaining quite intact. Bullets may be fired through a bundle or package
of cordite without detonating or inflaming it. This is of course a
valuable quality. The exact temperature at which substances ignite or
take fire is in all cases difficult to determine with any exactness.
Cordite is not _instantly_ ignited on contact with a flame such as that
of a candle, because, perhaps, of the condensation of some moisture from
the products of burning of the candle upon it. A blow-pipe flame or a
red-