536 Prof. Marianini's Exatnitiation of an Experiment 



A plate of gold with a surface of eight square centimeters, 

 coupled with one of platina having a surface of one square 

 decimeter, immersed in the said liquid, produced the deviation 

 of a degree and a half, which indicated that the gold was 

 positive in contact with the platina. 



And thus, with any other of the above-mentioned pairs 

 whatever, a current was obtained, which indicated that one 

 of the metals was positive and the other negative. 



XIII. But let us suppose that all these doubtful cases may 

 not argue against the chemical theory; let us admit that the 

 metal which shows itself positive may be also the most acted 

 upon; and that if this is not yet demonstrated, it will be proved 

 one day. What must we say of so many other cases, in which 

 it is certain which of the two metals is the most acted upon, 

 and equally certain that it is not electrified positively, as the 

 new theory would assert? 



Copper united with iron and immersed in ammonia is elec- 

 trified negatively in the first moment of immersion. The 

 same copper is charged also with negative electricity when 

 united with tin and with lead, the pair being immersed in the 

 same liquid ; yet the copper is more acted upon by the am- 

 monia than are the other two metals. 



In the nitric and sulphuric acids, diluted or concentrated, 

 are not copper and iron more acted upon than tin and lead ? 

 Yet copper as well as iron is electrified negatively when it is 

 immersed in the said liquid, united with tin or lead. 



Sulphuric acid, diluted by two hundred parts of water, acts 

 less upon cobalt than the copper, polished antimony, and 

 antimony slightly oxidated, which being immersed in the said 

 acid, promotes effervescence. But the pairs, cobalt and cop- 

 per, cobalt and antimony, immersed in the said acid, show 

 the cobalt always positive. 



Polished antimony, cobalt, bismuth, nickel, tin, and lead, 

 are all less acted upon by acetic acid than copper is; yet 

 they are all positive when, in voltaic association with copper, 

 they are immersed in the said acid. 



And here are twenty cases (and it is far from difficult to 

 find others) in which the two elements of the pair are im- 

 mersed in the same liquid, and the metal the least acted upon 

 is positive with respect to the other. And it may be said 

 that the experiments of the Genevan physicist must have been 

 restricted within very narrow limits, if not one of these cases 

 came under his notice; since, if the above fitcts are true, of 

 which whoever will repeat them may assure himself, it appears 

 to me impossible longer to admit, with M. de la Rive, that 

 "le sens du courant est toujours d'accord avec la theorie 



