1814.] On the Hypolheses of Galuanism. 35 



Among others. Sir H. Davy expressly mentions Voita's hypotiiesis 

 as an extension or generalization of Bennett's experiments, and 

 remarks that Bennett proved tliat bodies brought into contact, and 

 afterwards separated, exhibited dilferent states of electricity.* Mr. 

 Nicholson always seems to acknowledge their identity ; and Mr. 

 Murray, in giving an account of Volta's hypothesis, bays, that it 

 proceeds upon the fact that metals acquire dilferent states of electri- 

 city, when separated after having been in contact, f It must, 

 however, be considered as still more remarkable, if it should 

 appear that the two circumstantes have been confounded by Volta 

 himself; yet this seems to be the case; for in the experiments 

 related in his letter to Delametherie, he examined the metals sepa- 

 rately, after they had been in contact, and draws his inference from 

 this examination. J These remarks lead tts to the conclusion that 

 the experiments which have been brought forward in favour of the 

 electrical action of the metals in the pile are, tur the most part, not 

 applicable, that two difterent principles have been confounded 

 together, and that we have no proof that metals in perfect contact 

 can exhibit different states of electricity : by many experimentalists 

 it is asserted that this cannot be the case.§ 



Although 1 think there are strong reasons for this opinion, yet it 

 may not Ijc improper, in the present state of the question, to admit 

 the fact, and to examine respecting the hypothesis, whether it be 

 consistent with itself in all its parts, and how far it explains the 

 different plRuomena. Volta clearly lays down the position that 

 the chemical changes produced by the pile are not essential to its 

 operation ; that they are only secondary ; the eflTect, not the cause, 

 of the action of the apparatus. He insists that the action between 

 the metals is the essential part of the operation, while that between 

 the metal and the fluid is accidental, or less important ; that the 

 fluid serves merely to conduct the electricity of the metals, without 

 producing any change in its state, and that one fluid is preferable 

 to another only in conse- 

 quence of its being a better Fig. 1. 



conductor. The hypothesis 



may be thus illustrated (F/a. ci Zl Water C2 Z2 Water, &c. 



1).' C t and Z 1, by their 



contact, produce a change 



in their natural quantity of electricity, part of what belonged to C 1 

 is transferred to Z 1, so that C 1 becomes — , and Z 1 becomes + ; 

 and su|>posing that their natural share of electricity is represented 

 by 100°, and that the copper gives -f'^ to the zinc, C 1 and Z 1 

 will be brought to the states of 90° and 1 10° respectively. The 

 same alteration in their electrical states will, at the san)e time, 

 take place in the second pair of plates, C 2 and Z 2. The water 



• Phil. Trans. 1807, p. 32. + Elements of Chemistry, i. 581. 



X Nicli. Jonr. i. 138, &c. See also Delamotherie's account of Volta't bjpo- 

 ^be«is, Jour. Phyn. liv. 16; and Hcnry'i I'.leiii. i 24^. 

 S Cuttibertion, JSich. Jour. ii. 287 ; CAvaQo, at above. 



C 2 



