mokeless powders, such as cordite,
ballistite, and several others.

Nitro-glycerol, or glycerol tri-nitrate, was discovered by Sobrero in the
year 1847. In a letter written to M. Pelouse, he says, "when glycerol is
poured into a mixture of sulphuric acid of a specific gravity of 1.84, and
of nitric acid of a gravity of 1.5, which has been cooled by a freezing
mixture, that an oily liquid is formed." This liquid is nitro-glycerol, or
nitro-glycerine, which for some years found no important use in the arts,
until the year 1863, when Alfred Nobel first started a factory in
Stockholm for its manufacture upon a large scale; but on account of some
serious accidents taking place, its use did not become general.

It was not until Nobel conceived the idea (in 1866) of absorbing the
liquid in some absorbent earth, and thus forming the material that is now
known as dynamite, that the use of nitro-glycerine as an explosive became
general.

Among those who improved the manufacture of nitro-glycerine was Mowbray,
who, by using pure glycerine and nitric acid free from nitrous acid, made
very great advances in the manufacture. Mowbray was probably the first to
use compressed air for the purpose of keeping the liquids well agitated
during the process of nitration, which he conducted in earthenware pots,
each containing a charge of 17 lbs. of the mixed acids and 2 lbs. of
glycerol.

A few years later (1872), MM. Boutnny and Faucher, of Vonges,[A] proposed
to prepare nitro-glycerine by mixing the sulphuric acid with the
glycerine, thus forming a sulpho-glyceric acid, which was afterwards mixed
with a mixture of nitric and sulphuric acids. They claimed for this method
of procedure that the final temperature is much lower. The two mixtures
are mixed in the proportions--Glycerine, 100; nitric acid, 280; and
sulphuric acid, 600. They state that the rise of temperature upon mixing
is limited from 10 deg. to 15 deg. C.; but this method requires a period of
twenty-four hours to complete the nitration, which, considering the danger
of keeping the nitro-glycerine in contact with the mixed acids for so
long, probably more than compensates for the somewhat doubtful advantage
of being able to perform the nitration at such a low temperature. The
Boutnny process was in operation for some time at Pembrey Burrows in
Wales, but after a serious explosion the process was abandoned.

[Footnote A: _Comptes Rendus_, 75; and Desortiaux, "Traite sur la Poudr