of preparing and employing Gun-cotton. 541 



quality, which had been previously washed in a boiling solution 

 of carbonate of soda or of soap, and freed as far as possible from 

 all foreign substances, and particularly from fragments of cotton- 

 grains. Before using, it was carefully dried in a Gay-Lussae's 

 stove at a temperature between 100° and 115°. 



The sulphuric acid marked 66° on Baume's areometer. 

 The nitric acid had the density 1*500 at 9°; it was slightly 

 nitrous, and of a yellow colour. The relative proportions of sul- 

 phuric and nitric acids were varied so as to present (1) the com- 

 position of the Lenk mixture; (2) that of the Bouchet unequal 

 volumes ; (3) various proportions intermediate between 2 and 3 

 of sulphuric for 1 of nitric acid. 



The proportions of the mixture to the cotton were also varied, 

 so as to give that formerly used at Bouchet, that indicated by 

 General Lenk, and various proportions increasing to a limit 

 where the weight of the acid was 500 times that of the cotton. 



Lastly, the time during which the cotton was immersed in the 

 acids varied from one hour to sixty-six. In all these experiments 

 the yields varied within small limits without exceeding 178 for 

 100 of cotton. 



If weak acids are taken, or concentrated ones in which sul- 

 phuric acid is present in considerable quantities (8 or 10 parts, 

 for instance, to 1 of nitric acid), the yields are less. The same 

 is the case if the time of immersion is too much diminished and 

 is reduced to two or three minutes. Moreover, in these different 

 cases the product is not the gun-cotton as obtained by the me- 

 thods pursued at Bouchet and at Hirtenberg; it has smaller 

 ballistic effects, and it is generally soluble in a mixture of alcohol 

 and ether. 



The yields of the manufactory, whether at Hirtenberg or at 

 the Bouchet powder-mills, are far from those obtained in the 

 laboratory in small quantities. In fact, according to General 

 von Lenk, 64*50 kilogs. of un dried cotton are necessary for 100 

 kilogs. of gun-cotton, which corresponds to a yield of 155. Sup- 

 posing that the cotton contains 6 to 7 per cent, of moisture, the 

 yield of dry cotton would have been 165 to 167 per cent. The 

 constant yield at Bouchet when the manufacture had acquired a 

 certain regularity was 166-25 per cent. 



Without drawing from these numbers any conclusion respect- 

 ing the theory of the formation of gun-cotton, we cannot pass 

 over a circumstance so important as that of the virtually identical 

 yield obtained in the large establishments in question. 



III. Analysis of Gun-cotton. 



The composition given above, according to the German che- 

 mists, C 12 H 7 O 7 3 NO 5 , may be considered as that of a cellulose 



