GALVANISM. 367 



directly from discovery to application. In the same memoir which contained 

 the announcement of the subjugation of the alkalies and earths by the powers 

 of the pile, is found his brilliant hypothesis to explain the phenomena of vol- 

 canoes and aerolites. The metallic bases of the alkalies and earths cannot 

 exist at the surface of the earth in their simple or uncombined form, nor even 

 alloyed with the more perfect metals, because of the intensity of their affinity 

 for oxygen. But the same cause does not prevent their existence in the inte- 

 rior parts of the globe. Let the possibility of the existence of potassium, so- 

 dium, calcium, or any other metals of the same class in the inferior strata of 

 the earth, either in a separate state or in combination with other metallic sub- 

 stnnces, be admitted ; and it is only necessary to imagine their occasional ex- 

 posure to the action of air or water, to obtain a satisfactory solution for volcanic 

 eruptions. These highly combustible metallic principles, combining with ox- 

 ygen, attended by violent combustion, are ejected from the bowels of the earth, 

 and form the craters of volcanoes, the combination being an earthy matter ex- 

 hibited after its ejection as lava. The formation of aerolites might proceed 

 from the same causes, their luminous appearance and detonation being produced 

 by the combustion attending the combination of the metals with oxygen as they 

 enter the atmosphere. 



With a view to test the validity of these ingenious hypotheses, Davy inves- 

 tigated carefully the phenomena of active volcanoes ; and, not finding them to 

 be in sufficient accordance with these, he relinquished his theory, without any 

 of that regret which attends the failure of a favorite hypothesis, when the dis- 

 covery of truth is an object secondary to the attainment of personal distinc- 

 tion. 



The powers of decomposition and transfer by Voltaic electricity, so stri- 

 kingly exhibited in the researches of Davy, directed the attention of physiolo- 

 gists and others once more to the investigation of the agency of electricity in 

 the vegetable and animal economy. The experiments which had been made 

 to show that the alkaline and earthy elements found in organized vegetable sub- 

 stances were evolved, by the process of vegetation, from air and water, had 

 always been inconclusive and unsatisfactory ; and Davy's experiments, in 

 which it was shown that even in water carefully distilled there is still held in 

 solution a portion of saline or metallic matter, together with the known fact, 

 that air almost always holds in mechanical suspension solid matter of various 

 kinds, finally overturned such hypotheses. All the substances developed in or- 

 ganized nature may be produced, by ordinary processes, from combination of 

 known constituents. The compounds of iron, alkalies, and earthy bodies with 

 mineral acids, abound in vegetable soil. The decomposition of basaltic, gran- 

 iti^, and other rocks, affords a constant supply of earthy, alkaline, and ferru- 

 ginous matter to the superficial part of the earth. In the seeds of all plants , 

 which have been examined, nutro-saline compounds, containing potash, soda, A 

 or iron, have been found. It is easy to imagine that these principles pass from ( 

 vegetables to animals. 



The same analogies suggested to Dr. Wollasjon the idea, that something 

 < like the decomposing and transmitting powers of the pile is the agent to which 

 ? the animal secretions are due, especially as the existence of such agency in a 



> considerable degree of intensity, in certain animals, was proved by the effects 



> of the torpedo and Gymnotus electricus ; and he considered that the universal 

 prevalence of the same power, lower only in degree in other animals, was ren- 



| dered highly probable by the extreme suddenness with which the nervous in- 

 , fluence is propagated from one part of the living system to another. Although 

 ' the electric power of decomposition and transfer has been experimentally dem- 

 onstrated only in cases of comparatively high intensity of action, yet analog)' 



