32 On the Hypotheses of Galvanism. [Jan, 



found in the preceding Numbers of the Annals ; and the zoological 

 papers in the Philosophical Transactions will be noticed when we 

 give an analysis of that work. 



Article II. 



Remarks on the Hypotheses of Galvanism. By J. Bostock, 

 M.D. M.G.S. &c. &c. 



Galvanism may be defined a series of electrical phenomena, 

 produced without the intervention of an apparatus in which the 

 electricity is excited by friction.* 



Two hypotheses have been formed to account for the galvanic 

 effects — the electrical and the chemical. The first, which is the 

 hypothesis of Volta, supposes that a peculiar action of conductors 

 UDon each other is the first step in the process : the second, that a 

 chemical change in some part of the apparatus is the first step. 



An account of the electrical, or, as it is often called, the Voltaic 

 hypothesis, is given by Volta himself in letters which he, at different 

 times, wrote to his friends : 1st, In a letter to Cavallo: f 2dj In a 

 letter to Gren : X 3d, In a letter to Sir Joseph Banks : § ^th. In a 

 letter to Delametherie : || and 5th, In a letter to Van Marum. ** 

 The hypothesis, as stated in the letter to Cavallo, is entirely founded 

 upon the fact, that when metals are placed under certain circum- 

 stances, with respect to each other, electricity is produced. The 

 action is denoted by the phrase " destruction of the equilibrium of 

 the metals ; " and it is always spoken of as an action by which their 

 natural portion of electricity is altered, one of them becoming 

 positive, and the other negative. The effect produced by the two 

 metals upon each other is the only principle referred to in this paper. 

 In the letter to Gren another principle is brought forward, different 

 from the former. All conductors of electricity are divided into two 

 classes, the dry and the moist ; and electricity is supposed to be 

 always excited, when two conductors of one of these kinds are in 



• Is there properly an animal electricity? Can the parts of aoimals alone, 

 without the co-operation of any other substances, produce electrical phenomena? 

 This would appear to be the case in some of Aldini's experiments ; and, if the 

 account be correct, La Grave's animal pile decidedly proves the existence of an 

 animal electricity, (a) What was called by Galvani and Volta animal electricity, 

 is nothing more than electricity excited without the electrical machine, and ren- 

 dered sensible by its effects upon animals. Volta remarks, rrspecting these expe- 

 riments, that the animal is only to be considered as a delicate electrometer. Is the 

 action excited in the experiments of Aldini exactly similar to electricity excited 

 by other means ? 



+ Phil. Trans. 1793. + Ann. de Chim. xxiii. 276 (1797). 



^ Phil. Trans. 1800. if Nich. Jour. i. 8vo. 135 1 1801). 



»* Ann. deChini. xl. 225 ( 1802". 



(a) Jour, de Phys. Ivi. 235, 



