362 Mr. Faraday's Experimental Researches in Electricity. 



and in chemical force, the current of electricity of the standard 

 voltaic battery for eight beats of the watch was equal to that 

 of the machine evolved by thirty revolutions. 



377. It also follows that for this case of electro-chemical de- 

 composition, and it is probable for all cases, that the chemical 

 power, like the magnetic force (366.), is in direct proportion to 

 the absolute quantity of electricity which passes. 



378. Hence arises still further confirmation, if any were 

 required, of the identity of common and voltaic electricity, 

 and that the differences of intensity and quantity are quite suf- 

 ficient to account for what were supposed to be their distinc- 

 tive qualities. 



379. The extension which the present investigations have 

 enabled me to make of the facts and views constituting the 

 theory of electro-chemical decomposition, will, with some other 

 points of electrical doctrine, be almost immediately submitted 

 to the Royal Society in another series of these Researches. 



Royal Institution, Dec. 15, 1832. 



Note. — I am anxious, and am permitted, to add to this paper a correc- 

 tion of an error which I have attributed to M. Ampere in a former series 

 of these Experimental Researches. In referring to his experiment on the 

 induction of electrical currents (78.), I have called that a disc which I should 

 have called a circle or a ring. M. Ampere used a ring, or a very short 

 cylinder made of a narrow plate of copper bent into a circle, and he tells me 

 that by such an arrangement the motion is very readily obtained. I have 

 not doubted that M. Ampere obtained the motion he described ; but merely 

 mistook the kind of mobile conductor used, and so far I described his ex- 

 periment erroneously. 



In the same paragraph I have stated that M. Ampere says the disc 

 turned '■ to take a position of equilibrium exactly as the spiral itself would 

 have turned had it been free to move ;" and further on I have said that 

 my results tended to invert the sense of the proposition " stated by M. 

 Ampere, that a current of electricity tends to put the electricity of conductors 

 near which it passes in motion in the same direction." M. Ampere tells me 

 in a letter which I have just received from him, that he carefully avoided, 

 when describing the experiment, any reference to the direction of the in- 

 duced current; and on looking at the passages he quotes to me, I find that 

 to be the case. I have therefore done him injustice in the above state- 

 ments, and am anxious to correct my error. 



But that it may not be supposed I lightly wrote those passages, I will 

 briefly refer to my reasons for understanding them in the sense I did. At 

 first the experiment failed. When re-made successfully about a year af- 

 terwards, it was at Geneva, in company with M, A. de la Rive : the latter 

 philosopher described the results*, and says that the plate of copper bent 

 into a circle which was used as the mobile conductor " sometimes ad- 

 vanced between the two branches of the (horse-shoe) magnet, and some- 

 times was repelled, according to the direction of the current in the sur- 

 rounding conductors." 



I have been in the habit of referring to Demonferrand's Manuel d'Elec- 

 tricite Dynamique, as a book of authority in France; containing the general 



• Bibliothcquc Universcllc, xxi. p. 48. 



