Chap. 6.] Deflagration of Nitre. 27 



or detonation takes place. We are therefore not ro 

 confider nitre itfelf as an inflammable fubftance, but 

 only as affording the pabulum of fire. If we continue 

 to add charcoal, we find that the effect becomes lefs 

 and lefs, till it entirely ceafes. What remains in the 

 Crucible is different from nitre, it requires more heat 

 to keep it fluid, and upon examining it we find it a 

 pure vegetable fixed alkali. The charcoal difappears, 

 becaufe it is converted into carbonic acid gas by being 

 united with oxygen ; and the other component part of 

 nitrous acid, the azot?, by being deprived of its oxygen, 

 is alfo volatilized and difperfed. 



When the deflagration is performed with fulphtjr 

 inflead of charcoal, the confequences are confiderably 

 different. Like charcoal indeed, when fulphur is 

 added in a certain quantity, ic will produce no further 

 deflagration j but when fulphur is ufed, the flame is 

 infupportablc to the eye, and the appearance of in- 

 flammation is greater though the noife is lefs. If 

 fhe refiduum is difiblved in water, it will readily 

 cryftallize, and is found to be vitriolated tartar. The 

 reafon that icfs explofion is produced by fulphur than 

 Charcoal is, that the former, when united with the 

 oxygen of the nitre, becomes fixed ; whereas charcoal 

 united with the fame principle is converted into gas, 

 and efcapes with violence. The formation of vitrio- 

 Jated tartar is owing to the production of vitriolic acid 

 from the fulphur and the oxygen, which combines with 

 th'e fixed vegetable alkali. 



The detonation of nitre is a nice teft of the inflam- 

 mability of bodies, as there are many which are found 

 ;o have this property when added to nitre in a ftate 

 of fufion, which exhibit no figns of it on ordinary occa- 

 |icns. 



Nitre txifts in large quantities* in 'nature, and is 



continually 



