the Combustion of Gun-cotton and Gunpowder, 267 



the coiirse of the investigation it seemed advisable to extend the 

 method 1 used to gunpowder. 



I. Analysis of the Products of Combustion of Gun-cotton. 



The rapid deflagration of gun-cotton, and its necessary accom- 

 paniment, the bursting action, prevented me from using in the 

 analysis of the products of combustion the excellent method 

 which Professor Bunsen* devised, for obtaining the combustion 

 products of gunpowder for the purpose of analysis. It was ne- 

 cessary to effect the combustion in vacuo, and for this purpose I 

 used a eudiometer about a metre in length, in which, instead of 

 two wires, as in the ordinary eudiometer, a single very thin pla- 

 tinum wire was drawn across. To this from 15 to 20 milli- 

 grammes of gun-cotton were affixed, the tube filled with mercury, 

 and the Torricellian vacuum produced in the usual manner. By 

 means of a galvanic battery the wire could be ignited, and hence 

 the gun-cotton exploded ; thereupon all eudiometrical operations 

 were carried out in the tube in the usual manner, after a preli- 

 nary experiment had shown that the gas produced in this manner 

 consisted of nitrogen, binoxide of nitrogen, carbonic acid, car- 

 bonic oxide, marsh-gas, and aqueous vapour. Vol. 



at 0° 

 Volume. Pressure. Temp, and 1 m. 



Original volume . . . 374*53 0*1156 12 42-37 



In the steam-bath. . . 415-83 0-1768 95 54*56 



After absorption of NO 2 . 361-80 0*1078 11*2 37*47 



After absorption of CO 2 . 328*06 0*0850 10-5 26-85 



After addition of air . . 481*25 0*2372 12*3 109*26 



After addition of oxygen. 497*56 0*2510 12*5 119*41 



After explosion . . . 466-21 0-2212 11*2 99*07 



After absorption of CO 2 . 430*57 0-1855 10-4 76*97 



After addition of H . . 477*25 0*2301 11*7 105*29 



After explosion . . . 443*38 0*1983 12*6 84*08 



The quantity of NO 2 and CO 2 is obtained from the absorp- 

 tions, the quantity of water from the increase in volume in 

 the steam-bath ; the quantity of nitrogen is obtained from 

 the volume 76*97, which remains after removing the carbonic 

 acid resulting from the combustible gases, by subtracting the 

 uncombined oxygen and the nitrogen contained in the atmo- 

 spheric air added; while the combustible gases are calculated 

 from the formula? in Bunsen's gasometric method, 



Carbonic oxide —V l \ , Marsh-gas == " - 2 ~ j 



o 3 



Hydrogen . =P— P x , 



* Phil. Mag. vol. xv. p. 489. 



