490 POWDEKS WITH A NITKATE BASE. 



(3) The combustible substance, dried at 100, contained 



Carbon 73-6, that is, including the saline carbon of the ash 73-9 



Hydrogen ..................... 2-2 



Potassium ..................... 2-1 



Oxygen ..................... 21-8 



These numbers may be represented by the following empirical 

 proportions, C^B^KO^, which require 



C ............ 73-7 



H ............ 2-2 



K ... ................ 2-0 



..................... 22-1 



Of course it will be understood that it is not the question here 

 of a formula properly so called. 



These proportions, compared with those expressing the com- 

 position of cellulose, C^H^xAoo, show that distillation deprives 

 this substance not only of an excess of water, but also of an 

 excess of hydrogen, which corresponds with the formation of 

 methane, CH 4 , acetone, C 3 H 6 0, and analogous products. The 

 charcoal of the pith is therefore not a simple carbohydrate, but 

 contains a proportion of oxygen higher than that which would 

 correspond to such a composition. 



The proportion of oxygen contained in this charcoal, viz. 

 22 per cent., is very remarkable, on account of the physical 

 properties of the substance. We are here in presence of special 

 compounds having a very high equivalent, but the insolubility 

 and amorphous state of which prevent their being properly 

 determined. The author has elsewhere maintained the existence 

 of these moist and carbonaceous compounds formed by successive 

 condensations, and of which the various carbons represent the 

 extreme limit. 1 



6. TOTAL COMBUSTION POWDERS: SALTPETRE AND CHARCOAL. 



1. Two combustible elements being associated with the 

 combustive, it is easy to imagine an unlimited number of 

 powders of this kind. We shall consider the three following 

 cases : . 



(1) Mixture of saltpetre and charcoal. 



(2) Mixture of saltpetre and sulphur. 



(3) Mixture of saltpetre with sulphur and charcoal in equal 

 proportions. 



1 " TraitS de Chimique organique," p. 384 (1872) ; 2 e Edition, torn. i. p. 456 

 (1881) ; " Annales de Chimie et de Physique," 4 e se'rie, torn. xix. p. 143, and 

 torn. ix. p. 475. The analogy (torn. ix. p. 478) of these compounds with the 

 metallic oxides obtained by a more or less intense calcination, and which 

 r epresent products of successive condensation, was also maintained. 



