170 Miscellaneous Intelligence. 



it will go in the same direction as often as the experiment is repeated, 

 whether the operation be began on the right or on the left hand. 



If the bars be then well washed and dried, and restored to the ends 

 of the condenser wire they were in contact with before, but with that 

 part which was before immersed, now in contact with the wire, and 

 the immersions and experiment be repeated, one of two things will 

 happen, either the needle will constantly move to the east, whichever 

 bar is first immersed, or the action will be very doubtful or null. 



If, instead of turning the bars, they are changed one for the other, 

 the needle will go constantly to the "west, whichever bar is first im- 

 mersed; but the previous results may be at any time restored by 

 re-changing the bars, and then the needle will go to the east. 



The faculty thus acquired by the bars of zinc, of becoming positive 

 or negative, according as they are plunged either first or last in the 

 acid, they preserve some time. They may be washed, dried, and 

 held in the hand, without losing their state, and hence particular pre- 

 cautions are required in making delicate experiments with the metals. 



This faculty is not communicated either to the fluid or to the ex- 

 tremities of the condenser wire. All the metals which become mag- 

 netomoters by muriatic acid, as well as all the acids which produce 

 an electro-magnetic action with homogenous metals, produce the 

 same phenomena. 



These experiments may be compared, with interest, with the ob- 

 servations of M. Volta, that a band of wet paper, making part of the 

 conductor of his pile, becomes charged with electricities, which it pre- 

 serves some time ; with that of M. Gautheret, who thought he re- 

 marked something similar in the conducting wires of the pile, and 

 with that of M. Ritrer on his secondary piles, the phenomena of 

 which M. Volta attributed to the electromotive action of the alkalies 

 and salts interposed. '• A very decided electric charge may be remarked 

 in the metals interposed between the conductor and the fluid; they 

 are both unipolar, i. e., charged each with a single electricity, which 

 they retain for some time, and this electricity is constantly positive in 

 one, and negative in the other. They form, therefore, the elements of 

 a species of pile, of which the extremities may be detached without 

 losing their electricity ; and, in consequence of this property, I call it 

 a, secondary pile with mobile unipolar extremities." 



" I have sometimes succeeded, with bars of some length, in obtain- 

 ing distinct poles at each extremity, so that when the bars were turned, 

 opposite results were presented by the needle ; but I have not been able 

 to discover the conc.ition of this phenomenon, so as to be able to pro- 

 duce it at pleasure." 



M. Yelin remarks, however, that he has never yet been able to ascer- 

 tain the existence of free magnetism or electricity in any of these bars. 

 Many other experiments are given in tables, which we have not room to 

 notice, though they are of great interest. The bars M. Yelin used 

 were .275 of an inch in diameter, and 2.7*5 inches long. — Bib. Unh\ 

 axiii. 38. 



