POWDERS WITH BARIUM NITRATE. 517 



above the melting point, the mixture explodes towards 350. It 

 is hygroscopic. 



9. Lastly, the sulphur and carbon have been replaced by 

 a compound which contains both, such as potassium ethylsulpho- 

 carbonate, or xanthate (xanthine powders) 



Saltpetre 100 



Xanthate 40 



Wood charcoal 6 



11. POWDERS WITH BARIUM NITRATE BASE. 



1. Barium nitrate has been introduced into the composition 

 of the complex powders with special objects. The equivalent 

 of this salt (130*5) being higher by nearly a third than that of 

 potassium nitrate, it will be necessary to employ more of it. 

 For instance, the following proportion 



Barium nitrate 80 



Sulphur 8 



Charcoal 12 



will be equivalent to service powder. 



2. With equivalent weight, always assuming the same 

 chemical reactions, we should have nearly the same quantity of 

 heat and the same gaseous volume. But it will be necessary 

 to take a weight of powder greater by a little more than a fifth. 

 Hence, weight for weight, the heat will be diminished by about 

 a fifth, together with the volume of the gases and the strength, 

 for a given density of charge. 



3. The following mixtures, for example, have been proposed 

 lithofracteur, or saxifragine : 



Barium nitrate 77 



Wood charcoal 21 



Potassium nitrate 2 



Similarly the Schultze powders, a mixture of pyroxylated wood 

 with potasium and barium nitrates (p. 459). 



4. Barium nitrate is also employed in pyrotechny to produce 

 green fires. 



5. Strontium nitrate equivalent (1057) differs but slightly 

 from potassium nitrate. It is hardly employed, save in pyro- 

 techny to produce red fires. 



6. Lead nitrate equivalent (165*5) is capable of yielding for 

 equal equivalents a fifth more oxygen than the other nitrates ; 

 but the reactions which it develops are by this very fact all 

 different, since the lead is reduced to the metallic state, instead 

 of subsisting under the form of carbonates, as happens with 

 the alkaline nitrates. Besides, the high price of this substance, 

 and its high equivalent, hardly permit of its being used, except 

 for very special purposes ; for instance, by mixing it with red 

 phosphorus. 



