[ 193 ] 



XXXVII. Exammation of a Fourth Experiment adduced by 

 Professor Faraday in support of M. de la Rive's Theory^ 

 and regarded by Dr. Fusinieri to be demonstrative. By Dr. 

 Stephen Marianini, Acting Professor of Particular and 

 Experimental Physics in the University ofModena, 4 c. Sfc* 



" senza il corredo dell'esperienza non siamo siciiri che la na- 



turasiacon noi." — Romagnosi, DeWindolee deifattori delCmcivilmente, p. 3. 



"VIT'HEN in the summer of 1835 I undertook the researches 

 *' which form the subject of the preceding memoir 4th-|> 

 upon the theory of electromotors, I intended to treat of only 

 two of the experiments adduced by Professor Faraday in sup- 

 port of the theory of M. de la Rive; namely, of the electric 

 currents obtained by the immersion of platina and zinc in sul- 

 phuric acid, not placed in contact with each other In those 

 parts not immersed in the liquid; and of the spark obtained 

 by bringing the copper wire attached to a large copper plate 

 immersed in acid, in contact with the zinc wire attached to a 

 zinc plate immersed in the same liquid. The third fact brought 

 forward by Professor Faraday is the positive electrization of 

 copper, when, joined with iron, it is immersed in a solution of 

 sulphuret of potassa. I did not wish to speak of this as being 

 at all analogous to the other facts already adduced by M. de 

 la Rive, and which I had already shown in no way favoured 

 the new theory. But having seen that Dr. Fusinieri laid 

 great stress upon this same fact, I began to examine it, and 

 with, the assistance of clear and easy experiments, I think I 

 have shown that this also was not more favourable than the 

 others to the theory of the learned Genevan. 



1 did not write of the fourth experiment pointed out by Pro- 

 fessor Faraday, because, not only did it appear to me less con- 

 clusive tlian the others, but I also thought that it must appear so 

 to whoever is acquainted with what I have already published 

 on electromotors. I now see that I partly deceived myself, for 

 Dr. Fusinieri in the discussion into which he enters in some 

 pages of tlie Antiale delle Scienze del Regno Lombardo-VenetOi 

 relative to my aforesaid memoir, attaching not a little import- 



* From the author's Memoria de^Fisica Sperimetilale scritla dopo il 1836. 

 Anno sccundo, 1838. Modena, 1838, 8vo. 



•f The memoir here mentioned is inserted in vohinie 21 of the Memoirs 

 of the Italian Society of Sciences of Modena. Of the other three upon the 

 same subject, tiie first, read at the Athenieum at Venice on the 22nd of May, 

 1828, was aftersvards published in tiie 20th volume of those Memoirs; the 

 second was printed in Venice by Alvisopoli in 1830, and in the 45th volume 

 of the Annates dc Chimie el de I'hys'ique ; and tiie third, in the first bimcstre 

 for 1836 of the Scientific Annals of the Lombardo-Venetiau Kingdom. 



Phil. Mag. S. 3. Vol. 18. No. 116. March 1841. O 



