542 Prof. Marianini's Examination of an Experiment 



Every one knows that an electromotor of ten pairs has always 

 the same tension, whether the plates are large or small, or even 

 some small and others large. And it is known likewise, that 

 the quantity of electricity developed varies much with the va- 

 riation in the dimensions of o// the pairs, or even only of so?«^; 

 the galvanometers giving the most certain proofs of it. 



But granted even that this might be, is it then true that the 

 method by which I diminished the conductivity of the pile may 

 not concern this case, that is, alter the quantity of electricity 

 developed by each pair ? M. de la Rive seems to say, that 

 those pairs between the copper and the zinc, of which I 

 placed metallic diaphragms, are not in the same condition with 

 the other pairs. But the truth is, that it is not between the 

 copper and the zinc of one pair that I placed the diaphragms; 

 but between the zinc of one pair and the copper of another I 

 put some inactive pairs, that is, some arcs, formed of copper 

 wire, which were immersed in cups containing the liquid con- 

 ductor, as those which served for the active pairs. And this 

 interpolation I did not make mereljf between some pairs; but 

 in some experiments those arcs were interpolated between 

 every one of them ; so that all came to be in the same con- 

 dition. If ever M. de la Rive should say that those pairs so 

 interpolated are not in the same condition as those of another 

 electromotor, where there may not be that interpolation of in- 

 active pairs, and that, therefore, each pair of the interpolated 

 electromotor developes less electricity than each one of the 

 other, I would ask, 'whence the electricity is developed ac- 

 cording to the new theory? Is it not perhaps by the chemi- 

 cal action of the liquid upon the metal? and ought it not to 

 be proportional to the difference of the actions exerted upon 

 the zinc and upon the copper? Now, how do those inactive 

 arcs interrupt the action of the liquid upon the elements of the 

 pairs ; and then how do they alter the quantity of electricity 

 developed ? 



And if yet it should be pretended that the presence of that 

 inactive copper wire in the glass, where the zinc or the copper 

 of a couple was immersed, might influence the action exerted 

 by the liquid upon the zinc, or upon the copper of the same 

 pairs; what influence will the copper wires placed in the other 

 successive cups exert? The experiment shows that the ten- 

 sion is always the same, when placing one only of those inac- 

 tive arcs between the pairs of one pile, as when placing six, 

 eight, ten, or any other number whatever between them. 



And these observations, made relative to tension, apply also, 

 with the proper difference, to the decomposing power, which 

 always diminishes, when, the other things being placed simi- 



