574 
DR. H. DEBUS OR THE CHEMICAL THEORY OP GUNPOWDER. 
quantity, when compared wdth the amount given off by the formation of potassic 
carbonate, potassic sulphate, potassic disulphide, and carbonic acid. The following 
condition has a greater influence on the heat of combustion of ordinary gunpowder. 
The combustion ought to be complete; but in Bunsen and Schischkoff’s as well as 
in Linck’s experiments, a not inconsiderable portion of the powder remained unburnt. 
In every calorimetric determination all the products ought to be carefully examined, 
and this it seems was not done by those who have determined the heat of combustion 
of gunpowder. From the foregoing remarks we conclude that no close agreement can 
be expected between the heat of combustion calculated by means of equation (X.) for 
a mixture of 16 mols. of KN0 3 , y atoms of C, and z atoms of S, and that generated 
by an ordinary gunpowder containing saltpetre, carbon, and sulphur in the same 
proportions. 
In Bunsen and Schischkoef’s powder we have for every 16 mols. of saltpetre, 
13‘3 atoms of C, and 6‘3 atoms of S. If we substitute for y the number 13'3 and for z 
the number 6'3 in equation (X.), we obtain : 
W=1546688 cal. 
16KN0 3 -f 13*3C-b6*3S=1977*2 parts by weight, or one part of their powder would 
furnish 782 units of heat. Bunsen and Schischkoff found 619*5. This number is, 
I believe, the result of one experiment made with 0*71 grm. of powder; it is evidently 
much too small. Noble and Abel found, for the heat of combustion of the powders of 
Waltham Abbey, values which vary between 696 and 727 units. Their numerous 
calorimetric determinations were made by the combustion of the powders in the 
explosion apparatus, and several hundred grammes were used in each experiment. It 
is known that the combustion under such conditions is complete. But as the English 
powders contain much more carbon than Bunsen and Schischkoff’s, or 4 per cent, 
less of saltpetre, they ought to have produced less heat. From these considerations it 
seems to follow that in Bunsen and Schischkoff’s experiment a portion of the 
powder taken escaped combustion. 
It has been shown that 16 mols. of saltpetre, 21 atoms of C, and 5 atoms of S take 
part in the metamorphosis of the powders of Waltham Abbey. If for y the number 
21 , for ^ the number 5, are substituted in equation (X.), the value of W is found to be 
equal to 1427789 cal. ; but 16KN0 3 + 2lC+ 5S = 2028 parts by weight, hence 1 grm. 
of powder would generate 704 units of heat. 
Noble and Abel found in the first series, comprising five experiments, numbers 
which give a mean of 702‘34 units for 1 grm. of powder. 
In another series of 19 experiments greater numbers were obtained than in the first. 
The mean of all 24 experiments is equal to 719*9 cal. 
The theoretical number of 704 cal., however, corresponds to a mixture of saltpetre, 
sulphur, and pure carbon. 
93*75 per cent, of the English service powders are transformed, according to equation 
