188 
ME. ABEL’S EESEAECHES ON GUN-COTTON. 
placed in a very exposed position out of doors in front of a brick wall, where sunlight 
had access to them during the greater part of the day ; moreover, during the summer 
months, the heat radiated from the wall immediately behind the bulbs was considerable. 
The appearance of the gun-cotton and of the atmosphere in the bulbs was carefully 
examined periodically, but the former retained its original appearance, and no colora- 
tion by nitrous acid was ever observed in the latter. On the 1st of December, 1864 
(more than thirteen months after the commencement of the experiments), the tube 
enclosing the gun-cotton in a moist atmosphere was accidentally broken. The contents 
of this bulb w r ere therefore removed and examined. The gun-cotton was found to have 
a powerful acid reaction and a somewhat pungent odour, its fibre had become tender, 
but its explosiveness had not sustained any important diminution. The aqueous solution 
yielded upon evaporation only a very small amorphous residue, which consisted partly 
of alkaline and earthy salts derived from the gun-cotton. By exhausting one gramme 
of the material with water, neutralizing the solution with sodic carbonate and concen- 
trating by evaporation, abundant evidence of the presence of nitric acid was obtained. 
The aqueous extract acquired a yellowish colour upon addition of potassic hydrate, and 
a small quantity of cupric salt added to the alkaline liquid was reduced when lieat was 
applied. 
After treatment with water the gun-cotton furnished about 18 per cent, of matter 
soluble in a mixture of ether and alcohol. The solution, upon evaporation, did not 
furnish a tough film, but a horny brittle residue, which contracted and split up into 
small particles upon complete desiccation. This residue was explosive, and appeared to 
possess the characters of the lower nitrocellulose, G 18 j ©is- The acidity of the 
gun-cotton was determined in 5 grms. of the specimen, and was found to correspond 
to 2 per cent, of HN0 3 . 
A portion of this altered gun-cotton was placed in a stoppered bottle immediately 
upon removal from the bulb, and set aside in a cupboard to which light had imperfect 
access. After the lapse of two years (upwards of three from the commencement of the 
experiment) the specimen was again examined. Upon opening the bottle a faint odour 
of nitrous acid was perceived. A number of small very hard crystals were found firmly 
attached to the glass ; and similar crystals were interspersed through the material itself, 
which still retained the appearance of the original gun-cotton, having, however, con- 
tracted to some extent. On removal from the bottle it was found to be quite pulverulent ; 
it speedily attracted moisture from the air, passing over into a very adhesive mass ; it 
was soluble in water ; the solution, which was turbid only from suspended mineral 
matter, reduced cupric salts abundantly, and gave the reactions of parapectic acid, but 
was not found to contain glucose. 
A portion of the specimen of air-dry gun-cotton which had been enclosed with ordi- 
narily dry air in a bulb-tube at the same time as the sample just referred to, was also 
examined after it had been exposed for thirteen months, the remainder being left in 
