60 M. Pohl on White Gunpowder. 



100 parts 68-06 of solid residue, and 31-38 of gaseous products, 

 corresponding to 19310 cubic centims. From these data the 

 relation between the two substances is — 



Black powder. White powder. 

 The quantity of gas ... 1 : 2-107 



The temperature of flame . 1 : 0*641 

 The residues 1 : 0-77 



But for the respective temperatures of combustion the reduced 

 volumes of gas would be for black powder 231411 cubic cen- 

 tims., and for white powder 300798 cubic centims., and hence 

 the quantities of gas would be as 1 : 1-13. 



In the combustion in a confined space the temperature of the 

 combustion would be altered, for there would be a great differ- 

 ence in the specific heat of the products of combustion. Hence 

 the volume of gas, when reduced to the normal temperature and 

 pressure, would vary. For white gunpowder, Pohl calculates 

 the temperature of combustion in a closed space at 2604° C, and 

 the volume of gas furnished by 100 parts at 431162 cubic cen- 

 tims. Under similar circumstances Bunsen and Schischkoff 

 found that the temperature was 3340° C, and the volume of gas 

 258420 cubic centims. 



Hence the relation between the products of combustion in 

 confined space would be — 



Black powder. White powder. 



The temperature of the flames . . 1 : 0*779 



The volumes of gas 1 : 1-669 



As the action of an explosive powder principally depends on 

 the volume of the gases formed, for equal weights the new white 

 powder would produce 1 '67 times the action of the other. But 

 for equal volumes of the powder the ratio would be different. 

 Pohl found that a vessel which held 102-542 grms. of white 

 powder, held 132355 grms. of ordinary black powder. Hence 

 the density of the new powder in reference to the other would 

 be as 0-774 : 1, and the work performed by equal volumes would 

 be as 1-292:1. 



In order to produce the same effect on projectiles, in firing 

 mines, &c, 60 parts by weight of the new, would be required for 

 100 parts of the old. The weights of the residues in the two cases 

 are respectively 31 53 and 68 parts. Another advantage of the 

 white powder is, that the temperature of the flame is much lower ; 

 a greater number of shots could be fired without heating the 

 projectile too much. The new powder is more energetic in its 

 action than the old, and in this respect stands nearest gun-cotton. 

 It has the advantage over this substance of being cheaper and 



