

92 



REMARKS ON COMBUSTION. 



Kittle acid 

 formed fponta- 

 ncoufly i 



and alfo by elec- 

 tricity, through 

 common air, and 

 probably by gal- 

 vanifm j 



Apparently by 

 decombuftion. 



Nitric acid in 

 the procefs for 

 compofing wa- 

 ter. 



VIII. 



Remarks on Combuftion. By T h o m a s T h o m s on , M. D. 

 Lecturer on Chemiftry in Edinburgh. 



(Concluded from Page 20 J 



VI. INlTRIC acid is formed fpontaneoufly upon the furface 

 of the earth by proeefles with which we are but imperfectly 

 acquainted; but which certainly have no refemblance to com- 

 buftion. Its oxigen is probably furnifhed by the air, which is 

 a fupporter ; at leaii, it has been obferved, that if azote, the 

 inftant it is evolved, comes in contact with air, it is capable of 

 combining with its oxigen, and forming nitric acid. 



Nitric acid may be formed alfo, as Mr. Cavendifti has de- 

 monftrated, by pairing electric fparks through common air, a 

 fupporter. In all probability it may be formed alfo by the gal- 

 vanic pile, but this may be confidered as equivalent to eleclri- 

 city. This formation of nitric acid by means of electricity, 

 has been confidered as a combuftion, but for what reafon it is 

 not eafy to fay : the fubftance acted upon is not a combuftible 

 with a fupporter, but a fupporter alone. Electricity is fo far 

 from being equivalent to combuftion, that it fometimes acts in 

 a manner diametrically oppofite ; unburning, if I may ufe the 

 expreffion, a fubftance which has already undergone combuf- 

 tion, and converting a.produc~l into a combuftible and a fupporter . 

 Thus it decompofes water, and converts it into oxigen and hi- 

 drogen gas; therefore it muft be capable of fupplying the 

 fubftances which the oxigen and combuftible lofe when they 

 combine by combuftion, and form a product *. 



There is one procefs more, during which nitric acid is form- 

 ed, which muft at firft fight appear an exception to the general 

 rule ; I mean the formation of nitric acid, which takes place 

 during the combuftion of hidrogen gas in oxigen gas contami- 

 nated with air. But in this cafe it is the hidrogen only which 

 burns, and not the air; the air indeed combines intimately, 

 and forms nitric acid, juft as it does when electric fparks are 



* I do not mean to affirm that electricity never occafions com- 

 buftion, the contrary of which is weli known, but that a combina- 

 tion produced by it is not always the fame with combuftion. 



paffed 



