102 Theory of Galvanic Electriciijf, 



presented spontaneaiif.lv, and wlihont any foreign assistance, 

 by :tie batterv of Volta, when it is in full activity: the au-. 

 thor reckons seven principal ones. 



1. The peculiar smell it yields after some time, differing 

 a little according to the nature of the conductors, which are 

 generally metallic. 



2. The slight noise or crackling produced by a struiv bat- 

 tery, whether in the pile, or in the dish apparatus, and which 

 proceeds from the hydrogen gas libevalcd sometimes even 

 with a sort of white froth. 



3. The changes undergone by the humid conductors in 

 both of these kinds of apparatus, such as the decomposition 

 of water, the saline efflorescences, the presence of a free al- 

 kali when neutral salts are employed, Sec. &c. : the author 

 regards the more minute examination of these changes as a 

 vast field for new experiments. 



4. The oxidation of the metals. He here enibraces the 

 opinion of those who regard it as essential to Galvanic ac- 

 tion. It takes place, he savs, when the chain is formed, 

 not only in the atmospheric air, in the nitrous and oxvgen 

 gases, oxide of azote, in the acid gases, but also (although 

 more feebly) in the vacuum of the air pump, and in the 

 gases which contain no oxygen, such as hydrogen and 

 azotic gases. He finds in these circumstances what princi- 

 pally constitutes the difference of the battery of Volta from 

 the common electrical machine, in which there is no elec- 

 tricity produced without the presence of oxygen*. In the 

 Galvanic battery oxygen is furnished by the water, 1)y the 

 liquors which contain it, and by the acids; its action :.^ so 

 much the more powerful, as this principle is the more abun- 

 dant. 



.5. The absorpiion of oxygen. One of the most remarka- 

 ble experiments is that in which professor Schanb observed 

 the decomposition of common air under the bell glass; the 

 cessation of action when the oxygen is exhausted : the re- 

 newing of the action, even with a commotion, after we have 



* The author refers, for the development cf some of these propositions, 

 to the work he had previously published in two volumes under the title of 

 Jheory of Electricity. 



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