4-30 Mr. W. Crum on the Cojnposition of Gun-Cotton. 



In one experiment, 2*993 grs. of gun-cotton (after deduct- 

 ing water and ashes) yielded 7'952 cubic inches of gas, of 

 which 5'733 was carbonic acid, = 0739 grs. carbon, or 



2't*69 per cent. 

 A second experiment gave 25* 16 



Mean . . . 24.'92 

 Eletneiits of Water in Gjin-Cotton. — To burn gun-cotton for 

 the purpose of collecting its oxygen and hydrogen in the state 

 of water, I ground up 10 grains of it with pounded flint, and 

 used the combustion tube already described, having attached 

 to it a chloride of calcium tube, and afterwards a tube with 

 asbestos moistened with sulphuric acid. But along with water, 

 ammonia and other matters were obtained, which destroyed 

 the result. I next used a thin glass tube of a foot and a half 

 long, bent so that a foot in the middle of it could dip into 

 cold water. Such water as would condense at 65° Fahr. was 

 collected. The gas was led through it into a mercurial trough, 

 and measured. A trace of cyanogen appeared in the last por- 

 tions of gas, while the oxygen from the chlorate of potash was 

 burning a quantity of charcoal that had escaped the nitric 

 acid. 



After the experiment, the refrigerating tube was found 

 studded with large crystals of bicarbonate of ammonia. It con- 

 tained very little water in the liquid state. The crystals and 

 the liquid were washed out with more water, converted into 

 muriate of ammonia, and found to contain 0*675 gr. NHg 

 2CO2, the hydrogen of which represents 

 0*299 gr. of water. There were besides 

 2*025 grs. water in the tube. In the 22 inches of gas which 



were obtained, assuming it to be saturated with moisture, 



which is doubtful, there was 

 0"08S gr. of water — making in all 



2*412, from which must be deducted 



0*160 gr. hygrometric water in the gun-cotton and in the 

 flint, leaving 



2*252 for the water in 9*92 grs. 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 amount- 

 ed to 20*61 per cent. I did not proceed further. These were 

 the two last of a number of experiments, and the determina- 

 tions of nitric acid and carbon are so much more satisfac- 

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



Purified cotton wool (liguine) is composed of C,2 H,o Ojq. 



