Combustion of charcoal and of hidrogen. y?x 



was condensed, but much less than in the present. For 

 the 102*5 parts of gas remaining after the detonation were 

 reduced by potash and hidrosulphuret to C # 84 parts, which 

 indicate a condensation of 0*6 of nitrogen. - 



Hence it follows, that the.errours of Vbjta's eudiometer 

 are not equal with all mixtures, and that the indications of 

 . this instrument are more accurate* jn proportion as the g^s 

 analysed contains less nitrogen. • ' t 



When atmospheric air is analysed by Y°lta's eudiometer, With atmo- 



adding to it an equal bull? .of hidrogen according to the spheric ^ tbe 

 to ^ " o • errotirs balance 



usual practice, the mixture, when detonated, experiences each oth«r. 

 about the same degree of condensation, as if the process 

 with hidrosulphuret had been employed. \ satisfied myself 

 however by means of nitrous gas, that all the oxigen gas of 

 the atmospheric air had not been destroyed in the combus- 

 tion : but as some nitrogen was condensed, .this compen- 

 sated for the oxigen not destroyed. In this case the,indi- • 

 cation of Volta's eudiometer was accurate only in appear- 

 ance. ... . , • . . 



Lavoisier, .Fourcroy, Seguin, Vauquelin, and Cavendish, Compounds 

 found, that water formed by the combustion of' hidrogen ^^ !" ***** 

 and oxigen mingled with nitrogen sometimes*containfcd ha- hidrogen and 



trie or nitrous acid, and in other cases appeared- perfectly °xigen conia- 

 mi • -n i • ramaled with 



pure. The experiments of the French chemists indicate, nitrogen. 



that a slow combustion is the only mean of preventing the 

 developement of the acid. Cavendish however had said, 

 that when the combination of the gasses was effected by 

 detonation, or a rapid combustion, pure water was obtained 

 free from acidity, when the gas, according to his expres- 

 sion, was phlogisticated after the combustion: and, on the 

 contrary, that nitric acid was formed, when the oxigen gas 

 predominated in the combination. I have found, that the Nitric acul 

 observation of Cavendish was accurate in this respect, that always, 

 the water is acid, when there is an excess of oxigen gas; 

 but that it does not redden blue colours, when there is an 

 excess of hidrogen after the rapid combustion. At the same 

 time however I have observed, that the purity of the water 

 is apparent only, and that the want of acidity is not owing to 

 the absence of nitric acid, hut t® its neutralization by ammo- but in certain 

 nia, which is always formed with the nitric acid, eilher by ra- ^Tbjr 



pid 



cases neutrst- 

 m ammo- 

 nia. 



