Galvanic Apparatus, Theory of Galvanism, &e. 29 1 



continuous. As vet no adequate reasons have been given why, 

 jn operating with the pile, it is not necessary, as in the piocesses 

 of Van Marum and Wollaston, to inclose the wires in glass or 

 sealing wax, in order to make the electricity emanate from a point 

 within a conducting fluid. The absence of this necessity is ac- 

 counted for, according to my hypothesis, by the indisposition 

 which the electric fluid has to quit the caloric in union with it, 

 and the almost absolute incapacity which caloric has to pass 

 through fluids unless by circulation. I conceive that in galvanic 

 combinations, electro-caloric may circulate through the fluid from 

 the positive to the negative surface, and through the metal from 

 the negative to the positive. In the one case c;i!oric subdues -the 

 disposition which electricity has to diffuse itself througli fluids, 

 and carries it into ciTculation. In the other, as metals are ex- 

 cellent conductors of caloric, the prodigious power which electri- 

 city has to pervade them agreeably to any attractions which it 

 may exercise, operates almost without restraint. This is fully 

 exemplified in my galvanic deflagrator, where eighty pairs are 

 suspended in two recipients, forty successively in each, and yet 

 decompose potash vvith the utmost rapidity, and produce an al- 

 most intolerable sensation* when excited only by fresh river wa- 

 ter. I have already observed, that the reason why galvanic ap- 

 paratus composed of pairs consisting each of one copper and one 

 zinc plate, have not acted well without insulation f, was because 

 electro-caloric could retrocede in the negative, as well as advance 

 in the positive direction. I will now add, that independently of 

 the greater effect produced by the simultaneous immersion of iny 

 eighty coils, their power is improved by the proximity of the 

 surfaces, which are only about ,3-16ths of an inch asunder; so 

 that the circulation may go on more rapidly. 



Pursuant to the doctrine, which supposes the same quantity of 

 electricity, varying in intensity in the ratio of the number of pairs 

 to the (|uantity of surface, to be the sole agent in galvanic ignition, 

 the electrical fluid as evolved by Sir II. Davy's great pile nnist 

 have been nearlytwo thousand times more intense than as evolved 

 by a single pair, yet it gave sparks at no greater distance than 

 the thirtieth or fortieth of an inch. The intensity of the fluid 

 must be at least as much greater in one instance, than in another, 

 a», the sparks produced by it are longer. A fine electrical plate, 

 machine of thirty-two inches diamtter, will give sparks at ten 

 inches. Of course the intensity of the fluid which it emits, must 



• I do not say shock, as it is more like the permanent impression of a 

 pointed wire, and when acid is used a hot one. 



t That is, withtlie same mass of conducting fluid, in contact with all the 

 sui-faces, inst(!ad of hcinij divided into diffurent portions, each lestrictcd in 

 its action to one copper and one zinc plate. 



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