464 PICKIC ACID AND PICRATES. 



6. The solid residuum is formed of potassium carbonate and 

 cyanide, with a trace of carbon. The proportion of potassium 

 changed to cyanide, in 100 parts, amounted respectively to 29 '8, 

 347, 24'3. At the density 0'5, the reaction approximates to 

 the following formula : 



16C 6 H 2 K(N0 2 ) 3 = 4KCN + 6K 2 C0 3 4- 21C0 2 + 52CO + 



44N + 6CH 4 + 8H + 70. 



It tends towards 4CH 4 + 50 ; that is to say, the methane is 

 formed in an increasing quantity, according as the density 

 augments. On the contrary, the methane tends to disappears 

 for low densities. 



7. Heat of decomposition. The formula given above would 

 correspond to + 208*4 Cal. for 1 equiv. of picrate decomposed, 

 or 781-2 Cal. for 1 kgm. 



8. Volume of the gases. It would yield 146*5 litres (re- 

 duced volume) of gases per equiv., or 549 litres for 1 kgm. 



n .* . . T 5600 atm. 



9. The theoretical pressure = TTTT- 



n 014 



Sarrau and Vieille found 6700 kgm. at low densities of 

 charge, such as 0*023. 



It has been seen that for high densities the gaseous volume 



found tends to approach the theoretical figure. Now, at these 



p 

 high densities the ratio has been found by the same authors 



n 



at nearly 12,000 kgm., a figure which should be corrected 

 according to their recent experiments (p. 23). These point k to 

 about the half, or 6600 kgm., a value near the theoretical 

 figure, which would correspond, for n = 1, to 6700 kgm. It 

 will further be seen that it is greatly lower than the pressures 

 developed by nitroglycerin, or by gun-cotton, for the same 

 density of charge (p. 425). This is, in fact, as it should be, 

 according to theory, the heat liberated being less, weight- for 

 weight, as well as the volume of the gases. 



Potassium picrate, therefore, does not offer the advantages 

 which had been anticipated from it at first, from the abruptness 

 of its explosive effects. 



- 4 POTASSIUM PICRATE WITH NITRATE. 



1. The total combustion of potassium picrate by potassium 

 nitrate corresponds to the following formula : 



5C 6 H 2 K(N0 2 ) 3 + 13KN0 3 = 9K 2 00 3 + 21C0 2 + 5H 2 



+ 28N. 1 



2. The total weight of the substance in equivalents is 267 

 grins, of picrate and 263 grms. of nitrate ; in all, 530 grms. For 



1 The slow formation of 2 equiv. of bicarbonate is here neglected. 



