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XIV. Researches on Gun-cotton. — On the Manufacture and Composition of Gun-cotton. 



By F. A. Abel, F.R.S., V.P.C.S. 



Received April 10,— Eead April 19, 1866. 



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 vi^ith sulphuric acid, upon cotton-wool. In the earlier papers on gun- 

 cotton, published vtrithin a short period of the announcement (in 1846) of Schonbein's 

 discovery of a substitute for gunpow^der, 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. PSlouze, 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 Beaconnot obtained 

 from starch by its solution in cold nitric acid and precipitation by water. But in 

 November 184G that chemist published the results of experiments establishing decided 

 differences between the two bodies. The conclusion which PfiLOUZE 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 



Cl2 Hji O21 Ng (€12 H22 ©21 NJ. 



Not long afterwards, PfiLOUZE published conclusions varying somewhat from the pre- 

 ceding. He fixed the increase sustained by cellulose, upon its conversion into pyroxylin, 

 at between 74 and 76 per cent., and was led by these numbers and by direct analytical 

 data obtained with pyroxylin, to regard the formula 



C2,Hi;O,„5NO,(€,2Hi,02iN,) 



as correctly representing the composition of that substance. The increase in weight 

 which cellulose should sustain, by conversion into a substance of that composition, would 

 be 74-9 per cent., a number which corresponds closely with the results obtained in these 

 later experiments of PSlouze. 



MDCCCLXVI. 2 P 



