198 Prof. Marianini's Examination of an Experiment 



in each cup was contained the usual acidulated water, and in 

 each was immersed one end of the galvanometrical wire, which 

 was of copper. The circuit being complete, making the two 

 plates to communicate with each other metallically, after the 

 needle was quiet (it pointed to twenty-five degrees) I stirred 

 the liquid in the cup where the zinc was, but I did not per- 

 ceive any increase in the deviation. I interrupted the circuit, 

 and agitated the liquid, but after it was closed the needle 

 showed no greater deviation, or at least the increase was not 

 perceptible. Then at least the increase of power was less 

 than when the liquid was agitated whilst the two plates were 

 in the same cup; and still, according to the theory of M. 

 de la Rive, in this last case, the increase of power ought, on 

 the contrary, to be greater, because the chemical action 

 upon the zinc was increased, while that on the copper re- 

 mained unaltered. 



But again, if the experiment is repeated, leaving the liquid 

 in which the zinc is immersed always quiet and agitating that 

 in which the copper is immersed, almost the same increase 

 in the deviation is observed which was obtained in the ex- 

 periments in which the plates were in the same cup ; yet ac- 

 cording to the new theory, by strengthening the chemical 

 action upon the copper and not upon the zinc, the copper 

 ought to become less negative, and thence the current be- 

 come weakened instead of strengthened ; therefore, according 

 to the results of the examination hitherto made, the experi- 

 ment treated of contradicts the chemical theory, instead of 

 confirming it. 



VII. Shall, then, this little increase in the force of the cur- 

 rent which follows upon the agitation of the liquid, or upon 

 such a cleaning [pulimento^ Fr. decape) of the plates, remain 

 without explanation .'* I believe it will, so long as no other effect 

 is required to take place from that agitation than the increase 

 of the chemical action of the liquid on the metal. 



Since by this action either electricity is not developed, or 

 even if it is developed it is not that which circulates in the 

 electromotors, at least in ordinary cases, as I have shown, 

 with many experiments in my second memoir upon this sub- 

 ject * : thus the strengthening of this action on either metal 

 causes, of itself, no change in the current, as the preceding ex- 

 periments may show. But if from this agitation of the liquid, 

 besides the strengthened chemical action of the liquid itselt 

 upon the metals, we see result also an increase in the con- 



* Memoir upon the chemical theory of Voltaic Electromotors, simple 

 and compound. Venice, 1830. — Annates de Cfiimie et de Physique, Sep- 

 tember and October, 1830. 



