274 Messrs. Fovrett and Teschemacher on the 



be bent at such an angle as to prevent any of the mercury 

 entering the tube previous to combustion, and the combus- 

 tion must be continuous, which is readily etFected by carefully 

 applying the heat backwards as the cotton is ignited. With 

 these precautions, the evolution of the gas was not attended 

 with any such violence as to interfere with its collection, nor 

 was any portion of the charge thrown out unconsumed, 

 which would have been the case had the heat been applied 

 to the hinder portion first. Having collected a sufficient 

 quantity of the gas, we passed up into it, first a little caustic 

 potash, which absorbed the carbonic acid mixed with cya- 

 nogen gas, and then green sulphate of iron, which took up 

 the nitric oxide ; the remaining gas was mixed with half its 

 bulk of oxygen gas, and exploded in a detonating tube, show- 

 ing the quantity of carbonic oxide present ; the remaining 

 gas after the separation of the carbonic acid thus formed was 

 considered as nitrogen. 



Some of these constituents were unexpected by us, espe- • 

 cially the cyanogen ; its presence however was fully proved, 

 as we succeeded in forming prussian blue with it. The quan- 

 tity of mixed gases obtained from 52-33 grs. of gun-cotton 

 measured 100 cubic inches ; these mixed gases have the fol- 

 lowing composition : — 



Relative Cubic 



volumes, inches. grs. 



Carbonic acid 2 14-286 6759= /^[^^^ '''''■^'''" 



Cyanogen. . 1 7-143 3'965 = J.^^[^^ 



Nitric oxide . 5 35-715 1 1-478 = {^:^^^ ^^^ 



Carbonic oxide 5 35-715 10-714 = /^'^^^ ^«'"'^°"" 



L6-178 oxygen 



Nitrogen . . 1 7-143 2-154 = 2-154 nitrogen 



100-000 35-070 



100 grs. of the same would therefore give 64-550 grs. of the 

 mixed gases, and as the ultimate elements, 15-030 grs. of car- 

 bon, 31-680 grs. of oxygen, and 17-840 grs. of nitrogen. 



By passing the gases from the combustion-tube through a 

 tube containing fused chloride of calcium, we have separated 

 20 grs. of water, to be added to the gaseous products ; and 

 we observed a crystalline deposit, both in the combustion- 

 tube and in the one leading from it, together with 5 grs. of 

 carbon lining the combustion-tube, and resulting from the 

 decomposition of a part of the crystalline deposits after heat- 



'944 oxygen 

 815 carbon 

 50 nitrogen 

 gen 

 •ogen 



