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CHAPTEK X. 



POWDEES WITH A NITRATE BASE. 

 I- 



1. BLACK powder consists of a mixture of saltpetre, sulphur, 

 and charcoal. According to the relative proportions of these 

 three ingredients, there is obtained service powder, in which the 

 greatest possible strength is sought for ; sporting powder, in 

 which facility of inflammation and combustion are aimed at ; 

 and blasting powder, for which the most copious production of 

 gas is desired. Even the proportions of the ingredients of each 

 of these powders vary with different nations between very wide 

 limits. 



Few substances have been more studied than powders of 

 this kind, and there is a copious literature on this subject. It 

 is not intended to give here a detailed examination of them, 

 which may be found in a more complete manner in the 

 " Treatise " by Piobert, in the " Traite sur la Poudre, par 

 Upmann et Meyer " (traduit et augmente par Desortiaux), as 

 well as the long and important pamphlets written by Bunsen 

 and Schisckhoff, Linck, Karolyi, and especially by Noble and 

 Abel, Sarrau, Vieille, Sebert, etc. Here we shall confine our- 

 selves to examining the various powders from the point of view 

 of the chemical reactions developed by their combustion, as 

 well as the heat liberated, and the volume of the gases pro- 

 duced by these reactions. The results of theory with those of 

 experiment will be compared, as far as is permitted, by the 

 following circumstances, which are difficult to introduce into a 

 precise calculation : 



1st. The charcoal employed is not pure carbon. It contains 

 only 75 or 80 per cent, of this element, 2 per cent, of 

 hydrogen, 1 or 2 per cent, of ash, and 15 or 20 per cent, of 

 oxygen. 



2nd. Powder contains a little moisture, the quantity of which 

 varies, being, however, generally nearly 1 per cent. 



