516 POWDERS WITH A NITRATE BASE. 



tion of sodium for potassium in a defined salt, whether dissolved 

 or anhydrous, causes an almost constant liberation of heat, 

 whatever be the nature of the salt. Now, the alkaline metal 

 existing in the saline form, both in the powder and in the 

 products of combustion, its influence is eliminated in estimating 

 the heat liberated by combustion, that is when the heat is 

 estimated for equivalent weights of the sodium and potassium 

 salts. Weight for weight, on the contrary, much more heat 

 will be obtained with the sodium salts ; similarly, a larger 

 volume of gas will be obtained, since the equivalent of sodium 

 is lower than that of potassium. Various explosives proposed 

 for industrial purposes, such as Davy powder, pyronome, 1 Espir 

 powder, may be classed with this one. 

 Take for example 



Sodium nitrate 63 



Sulphur 16 



Wood sawdust 23 



This is a slow acting substance, employed in quarries, especially 

 to produce dislocations. It is not explosive either by heating, 

 ordinary shocks, or friction. It contains three to four per cent, 

 of moisture, a quantity which may increase to as much as 30 

 per cent, by its being in a damp place, but not without the 

 powder becoming deliquescent. 



The following have been found as the tensions in a closed 

 vessel : 



Densities of charge 0'4 1613 kgms. 



0-5 2401 



values differing but slightly from that of ordinary blasting 

 powder, which confirm the foregoing deductions. 



7. The sodium nitrate powders have sometimes been mixed 

 with dry sodium sulphate, or dried magnesium sulphate, to 

 check the absorption of moisture. But the remedy is merely 

 temporary, and of little efficiency. 



The potassium and sodium, and even barium nitrates, have 

 also been associated in the same explosive. 



8. We shall further mention Violette's mixture : 



Sodium nitrate 62-5 



Sodium acetate 37'5 



This mixture corresponds to a total combustion 

 10C 2 H 3 lsra0 2 + 16NaHT0 3 = ISCOaNTa, + 7C0 2 + 15H 2 + 16K 



The two salts may be melted together, which gives a very 

 intimate mixture. But if the temperature be raised slightly 



1 Under the latter name variable mixtures containing as combustive 

 elements the alkaline nitrate and potassium chlorate. This confusion should 

 be avoided, the chlorate base powders being highly dangerous. 



