Mr. Abel on Gun-cotton, 147 



The determinations of the comparative volumes of carbonic acid and 

 nitrogen have furnished results closely in accordance with those of 

 the direct determination of nitrogen. 



Since the specimens t>f gun-cotton analyzed always retained small 

 quantities of the products soluble in ether and alcohol, it was to 

 be expected that the proportion of nitrogen found would be slightly 

 below, and consequently 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 

 determining the composition of gun-cotton, which consists in re- 

 ducing the latter to cotton by means of potassic sulphydride. The 

 results show that, although the method is useful for controlling the 

 results obtained, by determining 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 sul- 

 phuric acid of spec. grav. 1*84, and 1 part of nitric acid of spec, 

 grav. 1*52). The results arrived at may be briefly summed up j as 

 follows : — 



Finely carded and carefully purified cotton-wool will sustain an 

 increase of weight varying between 81*8 and 82*5 upon 100 parts 

 of cotton, if submitted for 24-48 hours to treatment with a very 

 considerable excess (about 50 parts to I of cotton) of the acid mixture. 

 Similar results may also be obtained by repeatedly treating the same 

 sample of cotton for comparatively brief periods with fresh quantities 

 of acid, provided this treatment be not too greatly prolonged. 

 Lower results (somewhat above or below 78 upon 100 parts of 

 cotton) are obtained if the cotton be submitted to treatment with a 

 large excess of acid for only brief or for very protracted periods, or 

 if it be left for about 24 hours in contact with a comparatively limited 

 proportion of acid (10 or 15 to 1 of cotton). The increase of 

 weight which 100 parts of pare cellulose should sustain by complete 

 conversion into a substance of the formula G 6 H 7 N 3 O n , is 83*3 ; 

 if converted completely into a substance of the composition 

 G 2i H 36 G 18 , 5 N 2 O-, it should sustain an increase in weight of 77' 78. 



There is strong evidence that the differences between the highest 

 results furnished by carefully purified cotton-wool, and the number 

 83*3, are to be principally ascribed to the small proportions of foreign 

 matter still existing in the fibre at the time of its conversion. 



The maximum increase of wei&ht sustained by cotton of ordinary 



L2 



