1879.] 



Researches on Explosives. 



135 



powders as actually used ; but as these powders had different amounts 

 of moisture in their composition, and as, in use, these amounts of 

 moisture are found to vary considerably, giving rise, especially when 

 the powders are used in guns, to very different pressures and generat- 

 ing verv different energies, it has been considered desirable to correct 

 the above figures, the following being those that would have had place 

 had the powders, when fired, been perfectly free from moisture. 



1 grm. dry pebble 



W.A.R.L.G. 



W.A.F.G. 



C. & H. No. 6 



Mining 



Spanish pellet 



powder generates 721*4 gramme-units. 

 7257 

 738-3 

 764-4 

 516-8 

 767-3 



In their first memoir the authors gave reasons for considering 

 fallacious a temperature of explosion deduced (as has been done by 

 some authors) by dividing the number of gramme-units of heat by the 

 mean specific heat of the exploded powder at 0° C, but for purposes 

 of comparison they give below the temperature of each powder calcu- 

 lated upon the above hypothesis. 



Temperature of explosion of W.A. pebble 



W.A.R.L.G. 

 W.A.F.G. 

 C. & H. No. 6 

 Mining 



„ „ Spanish pellet 



powder 3899° C 

 3880° 

 3897° 

 4083° 

 2896° 



. 4087° 



The volume of the permanent gases generated by the explosion of 

 each of the six powders is as follows (calculated for 700° C. and 

 760 millims. pressure, and corrected for the amounts of moisture they 

 contained) : — 



1 gramme TV". A. pebble powder generates 278 - 3 cub. centims. 



W.A.R.L.G. 

 W.A.F.G. 

 C. & H. No. 6 

 Mining 

 Spanish pellet 



274-2 

 263-1 

 241-0 

 360-3 

 234-2 



It is of high importance to observe that the volume of the perma- 

 nent gases generated is in every case in inverse ratio to the units of 

 heat evolved, as is shown by the following arrangement of the results 

 already given : — 



