104 



Mr. Abel on Gun-cotton, 



[Apr. 19, 



Their absolute removal from specimens of gun-cotton, purified for analy- 

 tical purposes, was found to be almost impossible. 



The methods employed for determining the proportions of carbon, hy- 

 drogen, and nitrogen in gun-cotton, and the relative proportions of carbonic 

 acid and nitrogen furnished by its combustion, have been very carefully tested. 

 Four different methods of determining the carbon were employed, and 

 forty-nine successful estimations of that element have been accomplished 

 in a variety of products of manufacture. A number of very concordant hy- 

 drogen-determinations, and eighteen direct estimations of the volumes of 

 nitrogen furnished by the complete oxidation of gun-cotton, have been 

 made. The individual as well as the mean results obtained in these 

 analytical experiments correspond much more closely to the require- 

 ments of the formula €g N3 ^u — ^ej sN^O } trinitro-cellulose, 

 or H^^ O^, Og, trinitric cellulose) than to the formula recently as- 

 signed for gun-cotton by Pelouze and Maury, Q^^ Hgg O^^, 5 O-. The 

 determinations of the comparative volumes of carbonic acid and nitrogen 

 have furnished results closely in accordance with those of the direct de- 

 termination of nitrogen. 



Since the specimens of gun-cotton analyzed always retained small quan- 

 tities of the products soluble in ether and alcohol, it was to be expected 

 that the proportion of nitrogen found would be slightly below, and con- 

 sequently that the carbon-results would be somewhat above, those which 

 the chemically pure substance should furnish. The variations exhibited 

 by the analytical results do not exceed such as are ascribable to the above 

 cause. 



A number of experiments were instituted with Hadow's method of de- 

 termining the composition of gun-cotton, which consists in reducing the 

 latter to cotton by means of potassic sulphydride. The results show that, 

 although the method is useful for controlling the results obtained, by de- 

 termining the increase of weight which cotton sustains by treatment with 

 nitric acid, it does not afford sufficiently definite and trustworthy data to 

 render it applicable as a method of ascertaining the degree of perfection of 

 manufacturing products, i. e. the extent of freedom of a specimen of the 

 most explosive gun-cotton from admixture with the soluble varieties. 



The treatment of cotton with nitric and sulphuric acids has been varied 

 in many ways in laboratory experiments, with the view to examine fully 

 into the increase in weight sustained by the former, upon its conversion 

 into the most explosive gun-cotton, and to determine what circumstances 

 may exert an influence upon the amount of increase, — an acid mixture of 

 uniform strength being employed throughout the experiments (3 parts 

 by weight of sulphuric acid of spec. grav. 1-84, and 1 part of nitric acid 

 of spec. grav. r52). The results arrived at may be briefly summed up 

 as follows : — ■ 



. Finely carded and carefully purified cotton-wool will sustain an increase 



