1907.] 



on Fifty Years of Explosives. 



453 



Modern Explosives, 



In these tables are given : first, the quantity of gas formed by 

 the explosion ; second, the units of heat developed ; third, the 

 product of the units of heat and volume of gas which represents 

 approximately the comparative potential energy of the explosion. 



I say approximately, because, as I shall have occasion to point out 

 to you shortly, the units of heat and the quantity of gas vary very 

 considerably, dependent on the pressure under which the propellant 

 is exploded. In the present tables I have taken the transformation 

 at the pressures at which the propellants are generally employed in 

 guns. 



To two or three points I may direct your attention. 



You will note that, among the modern explosives, I have placed 

 Lyddite. It is not suitable as a propellant, on account of its capacity 

 for detonating ; but although, when detonated effectively, it will 

 reduce to dust the greater part of a cast-iron shell, you will observe 

 its potential energy is lower than that of the seven propellants with 

 which I have placed it. You will also note that the potential 

 energies of the modern propellants are about four times that of the 

 old gunpowder. 



Observe also that, with the Amide powder, in which sulphur is 

 altogether dispensed with, and which consists of 40 per cent, of 

 potassium nitrate, 3'S per cent, of ammonium nitrate, and '22 per 

 cent, of carbon, the potential energy is about 65 per cent, higher 

 than that of the old Waltham Abbey powders ; and, in spite of the 

 tendency of the ammonium nitrate to absorb moisture. Amide 

 powders might have displaced the old powders had the much higher 



