The Chemistry of Powder and Explosives - Sciencemadness Dot Org

EARLY HISTORY OF NITRATED CARBOHYDRATES 255
structive effects of heat. Samples of the pulped guncotton,
even in the most porous conditions, have been found to resist
change perfectly upon long-continued exposure to temperatures
which developed marked symptoms of decomposition
in the guncotton purified only as usual. The pulping process
applied to guncotton affords, therefore, important additional
means of purifying the material, the value of which may be
further enhanced by emploving a slightly alkaline water in
the pulping machine. The slightest change sustained by guncotton
is attended by the development of free acid, which,
if it accumulates in the material, even to a very trifling
extent, greatly promotes decomposition.
Numerous experimental data have been collected with respect
to the establishment and acceleration of decomposition
in guncotton by free acid whilst exposed to light or elevated
temperature. This acid is present either in the imperfectly
purified material or has been developed by decomposition of
guncotton or its organic impurities. Samples of guncotton
which, by exposure to elevated temperatures or for considerable
periods to strong daylight, had sustained changes resulting
in a considerable development of acid, have afterwards
been thoroughly purified by washing. When exposed to light
for months, and in some instances for two or three years
(up to the present time), they have undergone no further
change, while corresponding samples confined in close vessels
without being purified, have continued, in some instances,
to undergo decomposition, and the original substance
has been completely transformed into the products repeatedly
spoken of.
Abel found that the guncotton regularly produced at Waltham
Abbey contained a small amount of material soluble in etheralcohol,
an average amount of 1.62% in the guncotton which
was made by treating cotton with 18 times its weight of mixed
acid, and an average of 2.13% in the guncotton which was made
by the use of 10 parts of acid. "The employment of the higher
proportion of acid furnished results more nearly approaching perfection
than those obtained when the guncotton was left in contact
with a smaller proportion of the acid mixture. As far as can
be judged at present, however, from the general properties of
the products, the difference observed when the larger or the
smaller proportion of acid is used, is not of sufficient importance
to render necessary the consumption of the larger quantity of
acid in the manufacture." Abel was able to carry out satisfactory
combustion analyses, with the following average results;