Biographical Notice of Alexander Volta. 69 



He explained in the same manner, the cause of the burning 

 soils of Barigazin, of the burning fountain of Dauphiny, of 

 the igneous phenomena of Petramala, of Villeja, &c. ; the 

 inspection of places every where proved the correctness of 

 his explanation, vv^hich had besides the positive merit of point- 

 ing out the imperfectly known cause of these wandering 

 fires, and the advantage of shewing that this phenomenon was 

 not owing, as was supposed, to the presence of petroleum or 

 bitumen, in the places where it was manifested. 



Volta was led by the observations to which we have just 

 alluded, to ihe discovery of the electrical pistol, in which, 

 by means of an electric spark, the sudden combustion of 

 hydrogen, produces a loud explosion. It is this property 

 of electricity, of setting fire to inflammable gases, which, 

 combined with another discovery of Volta, that of the 

 electrophorus, gave birth to the hydrogen gas lamp. It is 

 also to the same property, that we are indebted for the most 

 exact mode of analyzing gases, particularly the eudiometer, 

 invented by Volta himself. This instrument, the use of 

 which, is to shew the proportion of oxygen contained in a 

 certain quantity of atmospheric air, depends on different 

 principles, all of which proceed from chemical affinities. 

 The mode proposed by Volta, and which has been acknowl- 

 edged by Humbolt and Gay Lussac, to be preferable to all 

 others, consists in mingling with the given quantity of at- 

 mospheric air, a quantity of hydrogen more than double the 

 quantity of oxygen, which is known to exist in the purest air, 

 to determine afterwards, by an electric spark, the combina- 

 tion of the two gases, and consequently the formation of 

 water, and to take one third of the total diminution of the 

 mixture, which is found to be the expression of the given 

 quantity of oxygen sought. 



It remains for us to speak of that discovery of Volta, which 

 has contributed most to his fame, viz, the new method of 

 producing electricity, which is called by his name, and which 

 will always remain a monument of the genius of this learn- 

 ed man, to whom it owes its origin. 



Galvani, being engaged in some anatomical experiments, 

 perceived that two heterogeneous metals, connected by 

 the intervention of a frog, suitably prepared, produced in 

 the muscles of this animal, a sudden commotion, simi- 

 lar to an electric shock. This learned gentleman and 

 some other philosophers, struck with this phenomenon, 



