540 Prof. Marianini's Examination of an Experiment 



But behold us finally at some of my experiments, which the 

 learned Genevan undertakes to examine. 



Such experiments are only variations of the last one above 

 recorded. In order to render the transmission of the electric 

 fluid through the electromotor more difficult, I put between 

 each two pairs several inactive arcs, that is, foimed of one 

 sole copper wire, and the tension was equal to that which was 

 observed when the electromotor was arranged as usual. Some- 

 times in such experiments the transmissiveness of the appa- 

 ratus becomes so much enfeebled, that there is no longer an 

 indication of a current even to the galvanometer, as, lor ex- 

 ample, when I introduced between the three active pairs three 

 hundred and ten inactive ones. Yet, notwithstanding, I found 

 no difference in the tension of those three pairs Irom when 

 they were arranged as usual, and the current excited by them 

 did not pass through the water of three hundred other glasses, 

 and the metallic arcs which put them in communication 

 with each other. And since M. de la Rive said that the de- 

 composing power of the electromotor apparatus must vary ac- 

 cording to the relation which exists between the conductivity 

 of the liquid which connects the two poles and the apparatus 

 itself, I therefore brought forward experiments which showed 

 that not to be true, because every time that I rendered the 

 passage of the current sensibly more difficult, by adding now 

 twenty, now forty, now a hundred inactive pairs, the decom- 

 position taking place at the poles became always slackened. 

 (§ XXXVI. and XXXVII.) And see how M. de la Rive 

 discourses about these experiments at pages 151 and 152 of 

 the work quoted. 



" La principale objection du savant italien a ete dirigee cen- 

 tre le principe que j'avais admis, savoir que les deux fluides 

 electriques accumules aux deux poles de la pile peuvent se 

 neutraliser directement par I'intermcdiaire de la pile elle-meme 

 qui lui sert de conducteur. D'apres ce principe, dit il, si Ton 

 diminue la conductibilite de la pile on doit augmenter la ten- 

 sion de ses deux poles; or, on ne produit pas ce dernier effet 

 en interposant dans le liquide qui scpare les couples, un plus 

 on moins grand nombre de diaphragmes de cuivre, interposi- 

 tion, qui cependant doit diminuer la conductibilite de la pile. 

 II y a plus ; cette interposition non seulement n'augmente pas 

 la tension, mais elle diminue meme le pouvoir chimique de la 

 pile dans la decomposition de I'eau ; cependant lorsque les 

 poles sont reunis par un conducteur imparfait, s'il est vrai que 

 la proportion d'electricite qui passe par ce conducteur et par 

 la pile depende de leur conductibilite relative, il doit en pas- 



