NEW CLASSES OF GALVANIC CONDUCTORS. 323 



certain with some precision the particulars of the pheno- medium be- 

 mena, that are afforded by soap applied to the galvanic ^s, but not 

 pil ,1 have observed nothing, that is not completely ex- for completing 

 plained by the definition of conductors of the fifth class. 

 Thus a prism of soap applied to the positive and negative 

 extremities of the two piles, each of which has the same 

 number of plates but in an inverted order, connects these 

 piles completely, as long as the object is not to complete 

 the galvanic circle; and give to their poles the same diver- 

 gences, as if they were connected by a perfect conductor. 

 But to obtain the physiological or chemical effects, that without a wet 

 require the completion of the galvanic circle, a wet con - ^e positive° 

 doctor must be placed between the prism of soap and the pole, 

 positive pole. If this interposition were made at the nega- 

 tive pole, it would have no effect. The reason why I men- 

 tion this experiment, which is only a corollary from what 

 has been already said, is to point out a very direct solution 

 of a point of theory, on which philosophers differ, that 

 may be drawn from it. 



It has been asked, what kind of electricity belongs ex- This leads to a 



clusively to each of the two different metals of the pile: and solution of * he 



' question, wne- 



opinions have been divided on the point. They who as- t her the silver 



sert, that the elements of the galvanic pile are silver, a or the zmc _ be 

 7 ° 1 . in the positive 



wet conductor, and zinc, ascribe the positive electricity to s t a te. 



the silver. They on the contrary who maintain, that the 

 proper combination is silver, zinc, and a wet . conductor, 

 consider the zinc as the metal charged with positive elec- 

 tricity. I have hesitated some time between the two parties, 

 for want of a direct unequivocal proof, and from unwil- 

 lingness to sacrifice my scruples to the authority of Volta 

 himself. Now it appears, that the properties of conduc- 

 tors of the fourth and fifth classes furnish the most direct 

 and palpable means of deciding the question. Among 

 several other analogous proofs, the following is one of the 

 most evident, and most easy to be exhibited. 



Between the last pair of plates of zinc and silver in any A piece of dry- 

 pile, place, a slice of perfectly dry soap, then establish a s ° ap Yl T)g 



. . l J J f) placed between 



communication between the two poles by the interposition the last two 



of an apparatus for decomposing water, and no chemical P ,ates > no f f - 



° 7 feet is prod uc- 



effect will be produced. With a camel-hair pencil lightly e d: 





moisten 



