MERCURY FULMINATE AND NITROGEN SULPHIDE. 27 



We will thus definitely obtain at the temperature t, supposed 

 higher than 360, and at the normal pressure, a volume of gas 



equal to 89'28 lit. (l + ^~\ 



At 5161 this would make 1776 litres from a weight of ful- 

 minate equal to 284 grms. Now, the capacity in which the 

 explosion took place being 50 cms. for 10 grms., would be 

 1*42 litres for 284 grms. Hence the corresponding pressure 



would be, by Mariotte's law, =s 1251 atm,, or 1293 kgms. 



per sq. cm. The experiment made with a crusher gave a 

 crushing c of 2*4 mms. Mercury fulminate belonging to the 

 class of explosives for which the duration of the development 

 of the pressure may be neglected (p. 23) compared with the 

 duration of working of the crushing apparatus, formula (2) 



(p. 24) should be applied, that is, 541 + 535^. This gives 1183 



4 



kgms. per sq. cm. Water between 1293 and 1183 is hardly 

 one-twelfth. 



Similarly for the density of charge 0*3 theory deduced from 

 Mariotte's law gives 1939 kgms., and the crusher 1871 kgms. 



It should further be noted that the value 1183 leads to 

 the specific pressure 5915 kgms., while the value 1871 gives 

 6233 kgms. (pressure of unit weight in unit volume) ; figures 

 which are sufficiently close to each other to allow of the mean 

 being taken 6100 kgms. in round numbers. 



2. Take, again, nitrogen sulphide. This body has been ex- 

 ploded in a closed vessel, and it has been found that 



NS ic= N + S, develops + 32,300 cal. 



To calculate the pressure at the moment of explosion the heat 

 absorbed by the vaporization of the sulphur must be deducted. 

 If this transformation took place towards 448, it would absorb 

 about 2600 cal., and there would remain + 29,700 cal. But .this 

 figure is still too high, the temperature of the sulphur being raised 

 during the explosion to a point at which this body resumes its theo- 

 retical gaseous density, instead of a triple density which it has at 

 448. This new transformation absorbs a considerable quantity 

 of heat, which we will estimate provisionally after the analogy 

 of the polymers at 15,000 or 20,000 cal. for S 4 , or 8000 to 

 10,000 cal. for S 2 . We thus arrive at about 24,000 cal., a 

 figure which will be employed in default of fuller knowledge. 

 Let us admit that the sum of the specific heats at constant 

 volume of nitrogen and sulphur be equal to 4'8 at every 

 temperature, and neglect the differences between the theoretical 

 specific heat of sulphur and its real specific heat, in the solid 

 and liquid states, in order to simplify the calculations. 



