PRESSURE OF EXPLODED NITROGLYCERIN. 425 



12. Pressure at the theoretical temperature 



713 V 1 + 27s) 18966 atm. 



= - , or 19,t)80 kgm. per square 



n n 



centimetre. 



13. Let us compare this result with the pressures observed 

 by Sarrau and Vieille by means of the crusher and with dyna- 

 mite at 75 per cent. 



They found under the density of charge 



- = 0-2 1420 kgm. 



n 0-3 2890 



0-4 4265 (3984 and 4546) kgm. 



0-5 6724 (6902 and 6546) 



0-6 9004 kgm. 



The volume occupied by the silica, after undergoing the 

 temperature of the explosion, may be estimated at Ol c.c. for 

 1 grm. of dynamite. Consequently, the volume occupied by 

 the gas yielded by 1 grm. of pure nitroglycerin would be equal 



4. 

 to - (n 0*1), neglecting the expansion of silica by heat. 



o 



We find in this way, referring the corrected densities of 

 charge to nitroglycerin, and calculating the pressures from the 

 results of the " crushers " 



n' = 6-5 c.c. ?r= 9230 kgm. 

 n 



4-3 c.c. .. . 12430 kgm. 



3'2 13640 



2-5 16800 



2-1 18900 



F 



It will be noticed that the values of - are not constant. 



n 



But here intervenes the new theory of crushing manometers by 

 Sarrau and Vieille (p. 23), which accounts for these variations 

 by the duration of decomposition of dynamite and tends to 

 reduce by one-half the figure obtained with very high densities 

 of charge. 



According to their new trials, made with very heavy piston, 



for the density ~ = 0'3, we obtain a pressure of 2413 kgm., 



7l> 



which corresponds to n' = 4*3 c.c. 



, = 10,376 kgm. 



71 



If we wish to compare with strict accuracy these figures with 

 the theoretical pressures, the heat yielded to the silica must be 

 taken into account in calculating the latter. Let the specific 



