370 



ME. J. E. PETAVEL ON THE PEESSUKE OF EXPLOSIONS. 



A 



Fig. 8. Valve and connecting cone. 



The numerous valves required during the present research were all substantially of the type shown in this 

 figure, though varying considerably in external shape according to the use for which they were 

 intended. The above design was used for the valves serving to regulate the initial pressure and 

 composition of the mixture in the experiments on gaseous explosives. The apparatus is fixed firmly to 

 the working bench by screws (not shown in figure) passing through the four corners of the metal block. 



Into this cylinder the copper tube is soldered for a distance of about three-quarters of 

 an inch. These cone joints are superior to the lead washer joints, inasmuch as they are 

 easily made or disconnected, last indefinitely, and remain gas-tight under all pressures. 



PART II. EXPERIMENTAL INVESTIGATION OF THE EXPLOSIVE PROPERTIES 



OF CORDITE.* 



The maximum pressure developed by explosives can be measured with considerable 

 accuracy by means of the crusher gauge, which was devised some thirty-five years 

 ago by Sir ANDREW NOBLE, t The classical work since carried out by this investigator 

 is too well known to need a mention here. Attention may, however, be drawn to one 

 of the more recent papers, in which NOBLE publishes the cooling curves of cordite 

 and describes the instrument by which they were obtained.^ The apparatus is in 

 principle not unlike an ordinary steam engine indicator, but the spring is initially 

 compressed by an amount corresponding to nearly the full pressure of the explosion, 

 and is automatically released when this pressure has been reached. By this ingenious 

 contrivance the violent oscillations of the spring, which would be set up by the 

 explosion itself, are avoided, and a clear record of the rate of fall of pressure is 

 inscribed. 



* The explosive used in the course of this work was issued, by order of the Secretary of State for War, 

 as representing the service cordite of the year 1902. Samples of three different sizes were included in the 

 issue, the nominal sizes being 50/17, 20/17 and 3f. 



t 'Proc. Roy. Tnst.,' vol. VI., p. 282, 1871; see also 'Phil. Trans. Roy. Soc.,' vol. 165, p. 49, 1875, and 

 'Phil. Trans.,' vol. 171, p. 203, 1880, &c. 



| 'Proc. Eoy. Inst.,' vol. 16, p. 329, 1900. 



