206 
ME. ABEL’S EESEAECHES ON GUN-COTTON. 
signs of less complete purification of the cotton previous to conversion, than the gene- 
rality of samples of English manufacture. It should also be observed that the extract 
by ether and alcohol after treatment of the samples with alcohol, possessed in several 
instances the characters of photographic collodion (the solutions furnishing tough trans- 
parent films upon .glass), which was not the case with any of the specimens of Waltham 
Abbey gun-cotton, and in only one or two instances among the samples from Stowmarket 
The ordinary ethereal extract from the English samples furnished a horny brittle residue, 
contracting greatly upon perfect desiccation, and appearing to consist chiefly of the 
product “ B ” described by Hadow as having the formula C 18 H 22 © 15 8N© 2 . No decided 
evidence was obtained in support of the conclusion that this difference in the character 
of the ethereal extract affected the stability of the gun-cotton. On the contrary, the 
Austrian samples used in experiments 71 and 72, which did not furnish an extract having 
the properties of good collodion, and only yielded 7 - 5 and 8 - 5 per cent, of total soluble 
matter, decomposed far more rapidly and completely than the specimen (experiment 76) 
which consisted chiefly of collodion gun-cotton. 
The destructive effect upon the structure of the fibre produced by the long-continued 
digestion of the gun-cotton in warm solvents, which is necessary for ensuring the extrac- 
tion as completely as practicable of the soluble matters, renders it very difficult to obtain 
reliable indications of the effects of heat upon gun-cotton deprived of those substances. 
The following experiments appear, however, to afford considerable support to the infer- 
ence drawn from some of the results of the heat-experiments just referred to, that the 
existence in gun-cotton of small proportions of organic impurities, resulting from partial 
oxidation of foreign matters enclosed in the cotton fibre, exerts a very prejudicial influence 
upon the stability of the material, and that there is no sound foundation for the opinion 
that any such influence is exerted by the lower cellulose-products, when associated in 
small or large proportion with trinitrocellulose. 
Experiments 77—80. — Four specimens of gun-cotton were extracted with ether and 
alcohol, by being twice digested for periods of twenty-four hours, in a considerable volume 
of the mixture, and afterwards washed. The dry specimens were then exposed for twelve 
hours (in two days) to 100° C., side by side with portions of the original samples. 
No. 1. — The original gun-cotton exhibited faint indications of disengagement of nitrous 
acid in ten minutes after first exposure ; the vapours did not become more abundant 
throughout the experiment, and, at the conclusion, the gun-cotton, which was strongly 
acid, had sustained a loss of 18*5 per cent. The extracted sample did not, throughout 
the experiment ; afford any indication of the disengagement of nitrous acid ; its acidity 
at the close was comparatively very slight, and it had lost only 3 - 5 per cent. 
No. 2. — This sample, as well as Nos. 3 and 4, contained considerably more soluble 
matter than No. 1 sample ; the original gun-cotton behaved quite similarly to No. 1, 
but the portion treated with the solvent evolved nitrous vapours in about fifteen minutes, 
and sustained much more rapid and considerable decomposition than the gun-cotton in 
its original condition. 
