544 MM. Pelouzc and Maurcy on the New Methods 



torn of a green glass tube perfectly pure carbonate of lead was 

 placed, then the mixture of a known weight of gun-cotton with 

 about fifty times its weight of free oxide of copper, then coarse 

 oxide, and lastly reduced copper. The carbonate of lead was 

 heated so as to expel the air in the tube until the disengaged 

 gas was entirely absorbed by potash. The combustion of the 

 gun-cotton was then made with all the precautions mentioned 

 above. On the completion of the combustion, the tube was 

 swept out with carbonic acid. All the nitrogen was thus 

 obtained in the gaseous state after the absorption by potash of 

 the carbonic acid produced. 



In this way we have always obtained from 12 to 12*4 per cent, 

 by weight for the nitrogen ; and these two determinations are 

 in perfect agreement with the formula which we adopt. 



The German Report does not mention the conditions under 

 which the estimation of nitrogen was made — a regrettable omis- 

 sion. We have felt it necessary to allude to this, because nitrogen 

 is that one of the elements which shows the greatest divergence 

 between the two formulae, and is therefore that which ought 

 most certainly to exhibit the true one. 



In our formula the hydrogen corresponds to 3'13, and in the 

 German one to 2*36. We have found numbers between 3*10 

 and 3 - 30. The German chemists have many times mentioned 

 2*8, — a number which, although inexact, is nearer our formula 

 than theirs. 



As to the carbon, we found 24- 75 and 25 per cent. ; but as it 

 only differs in the two formulae by about O0Q8, it is less fitted 

 than the other elements of gun-cotton for the control of its 

 composition. We may, however, remark that in this point 

 again the analyses in the Austrian Note give numbers as near 

 one as the other formula ; there is even an analysis in which the 

 carbon agrees perfectly with ours. 



In fine, both the gun-cottons manufactured under the condi- 

 tions we have mentioned — those of General Lenk, like the 

 Bouchet ones — have the same composition, corresponding to 

 the formula 



C 24 H 18 18 5N0 5 , 

 and not to the formula 



C i2 H 7 7 3N0 5 . 



IV. Action of Heat on Gun-cotton. 



General von Lenk attributes the bad results obtained in 

 France by the Commission of 1846, to the circumstance that 

 sufficient attention had not been bestowed on the preparation of 

 the gun-cotton, and that a definite and adequately nitrated com- 

 pound had not been taken. He therefore works under condi- 



