GUN-COTTON AND POTASSIUM NITRATE. 457 



Note further that during cooling the potassium carbonate is 

 charged into bicarbonate, which gives finally 



158C0 2 + 82KHC0 3 + 104H 2 + 96N 2 . 



Or 828 grms. of nitrate for 1143 grms. of gun-cotton ; in all, 1971 

 grms. The substance contains, therefore, for 1 kgm., 420 grms. 

 of nitrate and 580 grms. of gun-cotton. 



2. Sarrau and Vieille operated with equal weights, to assure 

 total combustion. These proportions correspond practically 

 with 



6[C 24 H 18 (N0 3 H) 11 9 ] + 68KN0 3 = 110C0 2 + 34K 2 C0 3 + 



87H 2 + 470 + 67N 2 

 or after cooling 



76C0 2 + 68KHC0 3 + 53H 2 + 67N 2 + 470. 

 The authors have found, with high densities of charge (0'3 and 

 0'5), that a mixture of carbonic acid, nitrogen, and oxygen, in 

 the following ratios of volume, is obtained 



52-3 ; 371 ; 10'7. 

 The formula gives 54'9 ; 33*4 ; 11'7. 



The difference shows that there probably exists a certain 

 quantity of nitrite. With low densities of charge (0'023) the 

 relative proportion by volume of carbonic acid increases (59*5), 

 nitrogen diminishes (33*8), oxygen disappears, and carbonic 

 oxide (5*0) and hydrogen (1*8) are obtained; the nitrite is 

 necessarily here present in a considerable quantity. Lastly, 

 in a combustion experiment at the atmospheric pressure, a 

 condition comparable to a miss- fire, the authors obtained for 

 100 vol. 



NO 363 



CO 29-5 



C0 3 29-0 



H 1-6 



N 3-4 



3. We shall give the calculations for the proportions (1) and 

 (2), which correspond to total combustion. Equation (1) 

 represents an exact combustion, without excess of oxygen; 

 giving rise to a liberation of 1606 Cal. (initial formation of 

 neutral carbonate and gaseous water), or of 1766 Cal. (bicar- 

 bonate, liquid water) ; l or for 1 kgm. of the substance, 815 Cal. 

 or 891 Cal. Note that each molecule of liquefied water H 2 

 increases the heat by + 10 Cal. Each equivalent of carbonate 

 changed into bicarbonate 



K 2 C0 3 + C0 2 H 2 liquid = 2KHC0 3 , 



further increases the heat by 4- 12 '4 Cal. If the water were 

 gaseous to commence with, the increase would be + 17'4 Cal. 

 Equation (2) represents a combustion with excess of nitrate and 



1 Neglecting the dissolving action of this water on the salt. 



