XIV. Researches on gun-cotton.—On the manufacture and composition of gun-cotton

Abstract

The general designations of pyroxylin and gun-cotton have been applied, up to the present time, to the several products obtained by the action of nitric acid, either alone, or in admixture with sulphuric acid, upon cotton-wool. In the earlier papers on gun­ cotton, published within a short period of the announcement (in 1846) of Schönbein’s discovery of a substitute for gunpowder, the action of nitric acid upon cellulose was assumed by the several investigators to furnish one single definite product, to which different formulae were assigned, based in some instances upon analytical results, in others upon the increase in weight sustained by the cotton on its treatment with nitric acid, or a mixture of nitric and sulphuric acids. Pélouze, who was the first to produce (in 1838) an explosive substance by the action of nitric acid on cellulose, originally believed this product to be identical with that which Braconnot obtained from starch by its solution in cold nitric acid and precipitation by water. But in November 1846 that chemist published the results of experiments establishing decided differences between the two bodies. The conclusion which Pélouze then arrived at, regarding the composition of pyroxylin, was founded upon the tolerably constant increase in weight (between 68 and 70 per cent.) of dry cotton-wool and paper, when submitted to the action of monohydrated nitric acid, either employed alone or mixed with an equal volume of concentrated sulphuric acid. He considered that nitric cellulose was the sole product of the reaction, and that it consisted of one equivalent of cellulose minus one equivalent of water, combined with two equivalents of monohydrated nitric acid, its formula being C 12 H 11 O 21 N 2 (C 12 H 22 O 21 N 4 ). Not long afterwards, Pélouze published conclusions varying somewhat from the preceding. He fixed the increase sustained by cellulose, upon its conversion into pyroxylin, at between 74 and 78 per cent., and was led by these numbers and by direct analytical data obtained with pyroxylin, to regard the formula C 24 H 17 O 17 , 5NO 5 (C 12 H 17 O 21 N 5 )