1874.] 



on Fired Gunpowder. 



417 



TABLE V. 



Showing the comparison, in tons per square inch, between the pressures actually 

 observed in a close vessel and those calculated from the formula (3). 



The authors consider that the accordance of this comparison with 

 observed results fully establishes the accuracy of their views. 



The data furnished by the foregoing enable the authors to determine 

 theoretically the temperature of explosion of gunpowder, which they find 

 to be about 2200 C. The correctness of this theoretical estimate they 

 confirm by experimental observations on the behaviour of platinum when 

 exposed to the temperature of explosion. In all instances thin platinum 

 wire or foil showed signs of fusion, but actual fusion took place only in 

 one instance. 



The mean specific heatot the non-gaseous products and their probable expan- 

 sion between C. and the temperature of explosion are next .discussed. 



The means of obtaining the tensions of the products of explosion in 

 the bores of ordnance, and the results obtained in this direction by the 

 Committee on Explosives, are then examined, as far as regards the 

 particular powders with which the authors have experimented. 



The correctness of the view propounded by E-obins, that the work 

 obtainable from gunpowder is not importantly increased by increments 

 to the weight of the shot, is confirmed by the authors, and the influence 

 upon the tension of tired gunpowder exerted by the existence of water in 

 powder is illustrated. 



The extent of communication of heat to the envelope (or gun) in which 

 the powder is exploded is next considered, and experiments and calcu- 

 lations are given to show that such communication of heat varies from 

 about 35 per cent, of the total heat generated in the case of a small 

 arm. to about 3 per cent, in the case of an 18-ton gun. 



A comparison is instituted between the pressures actually found to 

 exist ia the bores of guns and those which would follow from the facts 

 established by these researches. It is pointed out, on the one hand, 

 that the assumption, that all the products of combustion are in the 

 gaseous state, is irreconcilable with the pressures actually observed; and, 

 on the other hand, Bunsan and Schischkoff's hypothesis that the work on 

 the projectile is accomplished only by the permanent gases, without 

 addition or subtraction of heat, is shown to be equally irreconcilable with 



