508 MM. Bunscn and Schischkoff's Chemical 



ure of gas in the hermetically sealed combustion-tube may be 

 safely neglected as being infinitely small. Calculating the heat 

 of combustion of gunpowder on the assumption that its com- 

 bustible constituents burn with free oxygen, and taking the 

 heat of combustion of sulphur, of charcoal and of hydrogen as 

 found by Favre and Silbermann, we obtain the number 

 1039°1 C. 



The oxidation of the constituents of powder by the oxygen of 

 the nitre gives therefore far less heat than their combxistion with 

 free oxygen. This fact is by no means strange, when we con- 

 sider that the nitrogen, amounting to two-thirds of the weight 

 of the combustible constituents, must fix a considerable amount 

 of heat in its change into the gaseous foi-m. 



The temperature of the flame of powder, or the temperature 

 which would prevail in the burning mass if no heat were lost by 

 radiation or conduction, is obtained directly by dividing the 

 number 619°"5 by the specific heat of the products of combus- 

 tion. But this specific heat may be calculated from the sub- 

 stances contained in 1 grm. of exploded powder, as shown in 

 scheme D, by multiplying the weights of the substance in column 

 a of the following Table by the specific heats corresponding to 

 them in column b, and adding together the products. The 

 small quantities of KO, SO^, K Cy S^, 2NH4 O, SCO^, and HS, 

 whose specific heats are not known, may be safely disregarded, 

 since their influence would only aflfect the desired numbers to 

 a very inconsiderable extent. 



a. b. a X b. 



Sulphate of potash . . 04554 0-1901 008656 

 Carbonate of potash . 0-1362 0-2162 0.02944 

 Sulphide of potassium . 0-0229 0-1081 0-00248 



Nitre 0-0401 0-2388 0-00957 



Charcoal 0-0079 0-2411 0-00190 



Sulphur 0-0015 0-7026 0-00031 



Nitrogen 0-1075 0-2440 0-02623 



Carbonic acid . . . 0-2167 0-2164 004692 

 Carbonic oxide . . . 0-0101 0-2479 0-00251 



Hydrogen 0-0002 3-4046 000073 



Oxygen 00015 0-2182 00033 



1-0000 0-20698 



Dividing the number 619°-5 by 0-207, we obtain for the tem- 

 perature of the flame of powder burning freely in the air, the 

 number 



2993° C. 



If the powder burns in a closed space in which the gases cannot 



