founded on Experience. 103 



supplied some fresh air ; are phsenomena which prove, ac- 

 cording to M. lieidman, that this action requires oxygen, 

 and should be ascribed to a chemical operation. 



6. The immediate action of the battery of Volta iipcui 

 Bennet's electrometer. When we bring this instrument 

 near the hydrogen pole, the divergency of the gold leaves 

 is stronger than when we bring it near the oxygen pole. 

 Immediate contact is not necessary; it is sufficient when 

 the base of the electrometer communicates wilh the earth, 

 to establish a conductor in order to produce a divergency ; 

 certainly more feeble. It was not possible for ihe author to 

 ascertain two opposite states of electricity of the hydrogen 

 and oxygen poles. He employed with this view a very 

 strong battery of Volta, and im electrometer made of a very 

 narrow ?,,m.[ very sensible glass cylinder: establishing, by 

 means of a conductor, the communication of the hydro- 

 gen pole with the top of the instrument, the divergency 

 nearly carried the gold leaves to the sides ; and thev re- 

 mained in the same situation when he established the com- 

 munication with the oxygen pole, which would be inioossi- 

 ble in the case of two contrary electricities, if we jjut in 

 communication, by means of a good njetallic conductor, 

 the battery of Volta with a prepared frog, which does not 

 communicate with the ground, there is no movement; a 

 proof that in every Galvanic action there must be in reality 

 a discharge or a partition of the Galvanic electricity, w hich 

 has not taken place in this case. 



7. The seventh article, which finishes this section, has 

 for its object the spark of the battery of Volta, as seen in 

 the dark by Nicholson. The author also relates the observa- 

 tion of Pfafl', ITebebrandt, Biol, and flalle, that, indepen- 

 denlly of the closing of the chain by the two extremities of 

 the battery, there often appears a light upon the pile itself, 

 that is to say, upon the sides of the mclallic plates. M. lieid- 

 man thinks himself well founded in doubting this plucno- 

 menon, the observations of which appear to him not to have 

 been precise, or reconcileable with received principles. lie 

 prcMHues that in the dark we may close by the conductor a 

 G 4 part 



