Eleclro-Magnclic Experimenls. 49 



2d. A law, which I have not verified except in regard to the 

 action exercised by that sort of current, but which may be true in 

 general for each of the infinitely small portions of which electrical 

 currents may be supposed to consist, in order to calculate the 

 effects. 



I exhibited at the same sitting an instrument, in which the 

 longitudinal effect of the current, which takes place in a con- 

 ductor twisted spirally, is neutralized by the prolongation of this 

 conductor, which returns in a right line into the axis of the spi- 

 ral, from whic!» it is separated by the sides of a glass tube. This 

 instrument, suspended on a pivot Hke the needle of a compass, 

 possesses all the properties of it when acted upon by a magnet ; 

 its extremities represent exactly the poles in the situation in 

 which they oughi to be according to the theory. 



Sitting of the 13th November, 1820. 



I read a note upon the electro-chemical effects of a spiral of 

 iron wire, subjected to the action of the earth alone. The action 

 of the earth directing an electric current as well as it directs a 

 magnet, as I had announced to the Academy in its previous sit- 

 tings, I thought that this action might, like that of a magnet in 

 the experiment of M. Fresnel, influence the oxidation of an iron 

 wire in water. I therefore plunged under a small glass bell, in 

 a weak solution of chloruret of sodium, the two extremities of an 

 iron wire, which made thirty turns round a paper cylinder, the 

 axis of which was nearly parallel to the variation of the inclina- 

 tion of the needle. 



The two wires soon appeared covered with some bubbles ; they 

 were much more numerous on the wire which, according to 

 theory, answered to the negative pole of the pile. 



During three days which the apparatus remained in action, I 

 several times made the bubbles mount to the top of the bell, so 

 that no more remained on the wires. Every time new ones were 

 produced on the wire which had at first produced most, aiul re- 

 mained brilliant until the end of the experiment. The other wire 

 did not present any more, or at least very rarely, since it was oxi- 

 dized. The apparatus having been accidentally overturned, I was 

 unable to ascertain whether the bubble in the superior part of 

 the bell contained hydrogen, or a greater portion of azote than 

 atinos[)heric air ; or if it was air such a-s is ordiiuuily mixed in 

 water, and disengaged from it by the elevation of the tempera- 

 ture of the chamber. On repeating the experiment witli the same 

 apparatus, 1 bad only very feeble signs of the electro chcnucal ac- 

 tion. In fact, 1 have still some doul)ts as to the existence of that 

 action, which I purpose to clear up by new experiments, 



Voi. r,-J. No. 273. Jan. 1S21. G VII. On 



