576 DR. H. DEBUS ON THE CHEMICAL THEORY OF GUNPOWDER. 
sulphur, which shall, of all possible mixtures of this nature, possess the greatest 
energy; the results so obtained will be nearly correct for ordinary gunpowders. 
This would be the most general form of the problem of the explosion of gunpowder 
which could be proposed for solution to a chemist. 
Equations (IX.) and (X.), viz. :— 
.(ix.) 
W=1000[1827'154 — 16-925y—8’788z].(X.) 
at once show that, if for a given weight of saltpetre, 16 mols., the carbon and sulphur 
of the mixture were allowed to increase, the volume of gas generated by combustion 
would likewise increase, but the quantity of heat will grow smaller, and if the carbon 
and sulphur be diminished the gas will also become less, but the heat of combustion 
will increase. 
Noble and Abel have called attention to the fact'" that the products of heat and 
gas obtained by them in their various experiments with different descriptions of 
powder do not differ much from each other. The explanation of this interesting 
observation is to be found in equations (IX.) and (X.). 
The work which can be performed by a given weight of powder will, cceteris paribus, 
be proportional to the volume of gas and amount of heat, respectively, which the 
powder can produce by its combustion, and hence, will be proportional to the product 
of both. This is, however, only approximately correct, because, if we have to compare 
the work which two powders of different composition can produce, the gases given oft 
by the one will not contain the elements in the same proportion as those produced by 
the other; a portion of the energy developed will be consumed in the performance of 
interior work during the expansion of the carbonic acid. This portion is, however, 
very small. 
The product of (IX.) and (X.) is: 
W Y 
10440-88 — 12-09y 3 +1208-39^/»-15-952/2:+993 , 8675;— 5*0222 3 =j^^=E . (XI.) 
the factor 1000 in (X.) has been omitted, or W divided by 1000, and V by division by 
2 has been converted from volumes into molecules. 
The equations (IX.) and (X.) are based on the assumption that no carbonic oxide is 
formed during the combustion of a mixture of saltpetre, carbon, and sulphur. In 
consequence, the volume of gas calculated by formula (IX.) for a mixture of the com¬ 
position like those of Waltham Abbey is 1*8 per cent, smaller, and the amount of heat 
* Phil. Trans., 1880, p. 230. 
