GALVANISM. 353 



on the electro-chemical theory. The slow and gradual changes observed by 

 the geologist are indications of the more tranquil and incessant operations of 

 electrical agency. Where strata of pyrites and coalblende occur ; where the 

 pure metals or the sulphurets are found in contact with each other, or with any 

 conducting substances ; and where different strata contain different saline men- 

 strua, electricity must be evolved, and by its agency mineral formations would 

 probably be influenced or produced. 



These views, which have been recently confirmed by the observations of 

 Mr. Fox on the electrical condition of the metallic veins in Cornwall, were il- 

 lustrated by experiment. A mixed solution of muriates of iron, copper, tin, 

 and cobalt, was placed in the positive cup P, and distilled water in the nega- 

 tive cup N, the cups being connected by asbestos. The four oxides passed 

 through the asbestos to the cup N ; a yellow metallic crust was formed on the 

 negative wire, round the base of which the oxides collected in a mixed state. 

 In another experiment the carbonate of copper was diffused in minute subdi- 

 vision through water, and a negative wire placed in a small perforated cube of 

 zeolite in the liquid. Green crystals collected upon the cube and adhered to 

 it, the particles being incapable of penetrating it. By the multiplication of 

 such instances, Davy conceived that the electrical power of decomposition and 

 transference would afford a satisfactory explanation of some of the principal 

 facts in geology, and his anticipations have since been to a considerable extent 

 realized by the researches of Becquerel and others. " Natural electricity," 

 says Davy in the conclusion of this memorable paper, " has hitherto been little 

 investigated, except in the case of its evident and powerful concentration in 

 the atmosphere. Its slow and silent operations in every part of the surface 

 will probably be found more immediately and importantly connected with the 

 order and economy of nature ; and investigation on this subject can hardly fail 

 to enlighten our philosophical systems of the earth, and may possibly place 

 new powers within our reach."* 



His theoretical ideas on the application of electrical decomposition to the 

 splution of the phenomena of geology were seized with ardor by Guyton Mor- 

 veau. That eminent chemist, like Davy, endeavored to exhibit on a small 

 scale, by direct experiments, the processes which are continually going on in 

 the crust of the earth. The native oxide of antimony he regarded as an ex- 

 ample of slow transition from the state of a sulphuret to that of a pure oxide, 

 by means of the decomposition of water by subterranean electricity. By care- 

 ful examination of a specimen of this mineral, he observed that it still retained 

 the structure of the crystallized sulphuret of antimony, and even preserved par- 

 tially its metallic lustre, and inferred that a slow Voltaic action had changed 

 its composition without disturbing the arrangement of its constituent parts. To 

 support those ideas suggested to him in Davy's celebrated paper by direct experi- 

 ment, he submitted a piece of sulphuret of antimony to the action of a power- 

 ful voltaic apparatus. An odor of sulphuretted hydrogen was soon perceiva- 

 ble ; the liquid asumed a yellow color, and the sulphuret appeared of a darker 

 tint, and iridescent, indicating incipient decomposition. The negative plato 

 became black; and the positive one was coated with a light yellow incrusta- 

 tion, which proved to be the oxide of antimony. Thus it appeared that the 

 sulphuret of antimony was capable of being transferred immediately into the 

 oxide by the mere operation of the Voltaic forces. Other native sulphurets 

 were tried in like manner, and gave similar results.f 



During the twelve months next succeeding the date of the memoir above 

 noticed, Davy devoted his labors, and directed all the powers of his genius, to 

 the development of the consequences of the theoretical principles which he 



* Philosophical Transactions, 1807. t Annales de Chimie, torn, liii., p. 113. 



