298 ME. ABEL'S EESEAECHES ON GUN-COTTON. 



Supposing that the matter soluble m ether and alcohol in a specimen of gun-cotton 

 amounted to 2 per cent., and consisted of the compound C, the result of the analysis 

 should be affected by that impurity to the extent of about 0-1 per cent. An excess of 

 0-5 per cent, obtained in the examination of a sample should therefore indicate the 

 existence of 10 per cent, of compound C (readily soluble gun-cotton) in the sample ; or 

 if the specimen contained that percentage of compound B, this would only affect the 

 result by 0-3 per cent. It cannot be confidently asserted that the errors of the method 

 itself are ever less than from 0-3 to 0-5 per cent. 



It is evident, therefore, that this method of examining gun-cotton, though useful as a 

 mode of controlling the results obtained by determining the increase of weight which 

 cotton sustains by treatment with nitric acid, under varied circumstances, is not suscep- 

 tible of affording sufficiently definite and trustworthy results to render it applicable as a 

 method of ascertaining the degree of freedom from soluble gun-cotton, of products of 

 manufacture. 



Experiments on the increase sustained hy cotton in its conversion into gun-cotton. — 

 Hadow found that cotton-wool, by treatment with the strongest mixture of nitric and 

 sulphuric acids, sustained an increase of ' 81*34 per cent., that the gun-cotton produced 

 was quite insoluble in mixtures of ether and alcohol, and that the increase of weight 

 which cellulose should sustain by conversion into the trinitro-cellulose agreed very 

 nearly with the results of his experiment. 



Pelouze's earlier experiments fixed the maximum increase in weight sustained by 

 cotton upon conversion into gun-cotton at 76 per cent. But in the recent report of 

 Pelouze and Maury it is stated that, in a number of laboratory experiments in which 

 the composition of the acid-mixture, the proportions borne by the acid used to the 

 cotton treated, and the duration of the treatment, were variously modified, the increase 

 in weight of the cotton fluctuated within narrow limits, and did not exceed 78 per cent. 

 The authors are led, mainly by these results, to adopt the formula 



period with an acid-mixture wMcli differed from that employed in the manufacture of insoluble gun-cotton, in 

 containing SBL^ in addition. 



The substance possessed feeble explosive properties, was readily soluble in ether and in glacial acetic acid, 

 with the exception of a small proportion of foreign matter, which rendered the solution slightly turbid. The 

 results obtained by determinations of carbon and nitrogen in the substance corresponded very closely to the 

 proportions which should be furnished by Gj^ H^ Ojj, 7N 0^, as the following comparison shows : — 



