Mr. W. Crum on the Compositio7i of Gun-Cotton. 431 



During its transformation into gun-cotton, there is no indica- 

 tion of cliange in tlie proportions of its oxygen and hydrogen. 

 The difference, therefore, between the weight of the substance 

 employed and that of the nitric acid and carbon found by 

 experiment, is oxygen and hydrogen in the proportions which 

 form water. 



The experiments I have I'elated give the following for the 

 composition of gun-cotton : — 



52"G9 nitric acid, 



24''92 carbon, and leave 



22' 39 for the elements of water. 



100-00 

 These numbers are nearly in the proportions of 12C, 7H0, 

 3NO,. 



100-00 96-59 



Leaving a remainder of 3*41 per cent., consisting of 1-51 

 carbon, and 1-90 water. These however, are nearly the 

 proportions which form lignine. 



Found. Calculated. 



1-51 1-51=:12C ^ ,. . 



1-90 ]-88 = 10Ho|=''8""^" 



Gun-cotton, from the form in which it is produced, is not 

 one of those substances we can expect to obtain in absolute 

 purity. Every previous improvement in its preparation had 

 diminished this excess of unaltered cotton, and I had no reason 

 to suppose the last portion perfect, considering the difficulty 

 with which some of the previous stages of improvement had 

 been attained. 



The specimen I have thus examined consists, therefore, of — 

 96-59 gun-cotton (12C, 7H, TO, SNO^). 

 3-41 lignine (12C, lOH, lOO). 



100-00 

 And pure gun-cotton consists of — 



24-24= 12C. 24-24 = 12C. 



21-21= 7HO. 2-36= 7H. 



54-55= 3NO5. 14-14= 3N. 



59-26 = 220. 



10000 



100-00 

 It is lignine in which three atoms of water are replaced by three 

 atoms of nitric acid. 



