1813.] 



Scientific Intelligence* 



has shown, by numerous experiments, that it produces two very 

 important eifects. 1. It increases the rapidity of the combus- 

 tion. 2. It greatly increases the quantity of gasaous matter 

 evoh'ed. Upon these two circumstances the force of gunpowder 

 entirely depends. Proust has shown that the quantity of sulphur 

 ought not to exceed 12*5 grains, supposing the nitre to amount 

 to 75 grains, otherwise the rapidity of the combustion is dimi-» 

 nished. Charcoal having a much greater affinity for oxygen 

 than sulphur, the combustion of the gunpowder ought, theo- 

 retically speaking, to depend upon the charcoal. There can be 

 little doubt, that it is the charcoal chiefly which burns ; though 

 probably the sulphur likewise comes in for a share. It is obvious^, 

 that the charcoal can serve no purpose whatever in the powder, 

 except as far as it is consumed. Now 'JG parts of nitre contain 

 about 38 parts of nitric acid. The quantity of oxygen in this 

 acid has not been ascertained in an unexceptionable manner ; 

 but, by the highest calculation, it cannot amount to more than 

 five times the azote present ; and there is reason to believe that 

 it does not fall far short of that quantity. Hence it is probable, 

 that the oxygen present in 7^ parts of nitre amounts to 30 parts. 

 We are certain that it cannot exceed that quantity. Now 15 

 parts of charcoal require for combustion no less than 37*5 parts 

 of oxygen. The quantity of charcoal which would consume 30 

 parts of oxygen would be 12 parts. From these considerations, 

 it follows, that the best proportions of the constituents of gun- 

 powder would be the following : 



Nitre 76 



Charcoal 12 



Sulphur 12 



100 



Or, perhaps, the sulphur might be diminished to ten parts^ 

 without impropriety. For it appears from Proust's experiments, 

 that such a proportion of sulphur would produce its full efFecte 

 The advantage of these new proportions would be a stronger 

 powder, or at least as strong a powder, two per cent, lighter 

 than the powder at present in use. 



VI. Test of Alimma, 



Mr. J. Gotlieb Gahn, the celebrated discoverer of the metallic 

 nature of manganese, and of the composition of the earth of 

 bones, has pointed out a valuable test for discovering the presence 

 of alumina in mineral substances exposed to the action of the 

 blow-pipe. It is as follows. Place upon the substance to be 

 tried a drop of nitrate of cobalt, and expose it to the white 

 Mame of the blow-pipe. If the mineral contain alumina in any 

 quantity^ and Is not too much charged with iron, or other 



E 2 , ' 



