102 . GUNPOWDER. 



weak attraction with a portion of nitrogen. The finely- 

 powdered charcoal has a very strong attraction for 

 oxygen, and when sufficiently heated is able to decom- 

 pose the nitre, seizing upon the oxygen of the nitric 

 acid, and forming carbonic acid, a small portion of 

 which combines with the potash of the nitrate, and 

 forms carbonate of potash. 



209. The use of the sulphur in gunpowder is simi- 

 lar to its use in the lighting of a common sulphur 

 match ; it very easily catches fire, and the flame thus 

 produced instantly heats the charcoal so much that it 

 is able to decompose the nitre. 



210. The mechanical force of gunpowder when 

 fired, is occasioned by the instantaneous production 

 of a large quantity of gas from a small bulk of solid 

 matter: as the whole of the nitrogen, and the greater 

 part of the carbonic and sulphurous acids formed, are 

 given off in the gaseous state, and comparatively little 

 is absorbed by the potash. 



211. During the burning of gunpowder, a small 

 portion of sulphuretted hydrogen is commonly formed, 

 which occasions the bad smell (182) commonly per- 

 ceived: the hydrogen necessary for the formation of 

 this gas is derived from a little moisture which gun- 

 powder generally contains; pure and perfectly dry 

 gunpowder contains no hydrogen, and hence, in its 

 firing, no sulphuretted hydrogen can be found. 



212. Nitre is one of the few compounds of nitric 

 acid which are found native, and, indeed, it was till 

 lately almost the only source of that acid. It is also 



