ate.

[Footnote A: Eng. Pat. 24,662, 22nd November 1898.]

The discovery of gun-cotton is generally attributed to Schoenbein (1846),
but Braconnot (in 1832) had previously nitrated starch, and six years
later Pelouse prepared nitro-cotton and various other nitro bodies, and
Dumas nitrated paper, but Schoenbein was apparently the first chemist to
use a mixture of strong nitric and sulphuric acids. Many chemists, such as
Piobert in France, Morin in Russia, and Abel in England, studied the
subject; but it was in Austria, under the auspices of Baron Von Lenk, that
the greatest progress was made. Lenk used cotton in the form of yarn, made
up into hanks, which he first washed in a solution of potash, and then
with water, and after drying dipped them in the acids. The acid mixture
used consisted of 3 parts by weight of sulphuric to 1 part of nitric acid,
and were prepared some time before use. The cotton was dipped one skein at
a time, stirred for a few minutes, pressed out, steeped, and excess of
acid removed by washing with water, then with dilute potash, and finally
with water. Von Lenk's process was used in England at Faversham (Messrs
Hall's Works), but was given up on account of an explosion (1847).

Sir Frederick Abel, working at Stowmarket and Waltham Abbey, introduced
several very important improvements into the process, the chief among
these being pulping. Having traced the cause of its instability to the
presence of substances caused by the action of the nitric acid on the
resinous or fatty substances contained in the cotton fibre, he succeeded
in eliminating them, by boiling the nitro-cotton in water, and by a
thorough washing, after pulping the cotton in poachers.

Although gun-cottons are generally spoken of as nitro-celluloses, they are
more correctly described as cellulose nitrates, for unlike nitro bodies of
other series, they do not yield, or have not yet done so, amido bodies, on
reduction with nascent hydrogen.[A] The equation of the formation of
gun-cotton is as follows:--

2(C_{6}H_{10}O_{5}) + 6HNO_{3} = C_{12}H_{14}O_{4}(NO_{3})_{6} + 6OH_{2}.
Cellulose. Nitric Acid. Gun-Cotton. Water.

The sulphuric acid used does not take part in the reaction, but its
presence is absolutely essential to combine with the water set free, and
thus to prevent the weakening of the nitric acid. The acid mixture used at
Waltham Abbey consists of 3 parts by weight of sulphuric acid of 1.84
sp