168 Mr. Crum on the Analysis of Nitrates, and on Explosive Cotton. 



water, converted into muriate of ammonia, and found to contain 0*675 



grain NH 3 2 C0 2 , the hydrogen of which represents 



299 grain of water. There was besides 



2*025 grains water in the tube. And in the 22 inches of gas which were 



obtained, assuming it to be saturated with moisture, which is 



doubtful, there was 

 0*088 grain of water — making in all 



2*412, from which must be deducted 



0*160 grain hygrometric water in the gun-cotton and in the flint, leaving 



2*252 for the water in 9*92 grains of dry gun-cotton, or 22*70 per cent. \ 



In a second experiment, where the only difference was in having 

 moistened cotton for the gas to pass through before entering the mercurial 

 trough, the water obtained only amounted to 20*61 per cent. I did not 

 proceed farther. These were the two last of a number of experiments, 

 and the determinations of nitric acid and carbon are so much more 

 satisfactory, that I prefer resting the water contents upon their results. 



Purified cotton wool (lignin) is composed of C 12 H 10 O 10 . During its 

 transformation into gun-cotton, there is no indication of change in the 

 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 related give the following for the composition 

 of gun-cotton : — 



52*69 nitric acid, 

 24*92 carbon, and leave 

 22*39 for water. 



100*00 

 These numbers are nearly in the proportions of 12 C, 7 HO, 3 N0 5 . 



Found. Calculated. 



52*69 52*69 = 3 N0 5 . 



24*92 23*41 = 12 0. 



22*39 20*49 = 7 HO. 



100*00 96-59 



Leaving a remainder of 3*41 per cent., consisting of 1*51 carbon, and 190 

 water. These, however, are nearly the proportions which form lignin. 



Found. Calculated. 



1*51 1-51 = 12 



1-90 1-88 = 10 HO 



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 



I = lignin. 



