56 M. Despretz on the Electricity 



centimetre, afforded under the same circumstances deflections 

 of 11°, 24° and 85°. The gold, which was perfectly pure, 

 had been recently prepared at the Mint of Paris, in the labo- 

 ratory of M. Pelouze and M. Peligot. The needle, when set 

 free, took about half a minute in moving from 50° to zero. 



I was not at first acquainted with M. Reymond's method of 

 proceeding. In my earliest experiments, two cylindrical 

 conductors were held in the hands, and when the needle had 

 returned to zero, or had acquired a perfectly stationary posi- 

 tion, one of the arms was powerfully contracted ; the deflec- 

 tion was then observed, and when the needle had again be- 

 come stationary after the cessation of the contraction, the other 

 arm was strongly contracted, also observing the deflection. 



These first experiments were made with common copper 

 conductors. But for the sake of avoiding the objection which 

 might arise from the ready oxidation of this metal, I had 

 them covered with gold-leaf. Other conductors were coated 

 with silver, platinum and gold. 



The experiments were made by three persons. Were there 

 no occasion for using galvanometers, we should be inclined to 

 believe that silver, and especially gold and platinum, which 

 preserve their polish and lustre in contact with moist air, 

 would be appropriate for these experiments, on account of 

 their unalterability. This is however not the case; silver, 

 gold and platinum afford currents which are almost as strong 

 as copper. When the platinum conductor is held in the 

 hand, and the needle has become stationary, merely touching 

 it with one finger more, or less, is sufficient to change the posi- 

 tion of the needle several degrees. 



In these experiments the needle was deflected 50°, 75° and 

 even 90°. When one of the conductors was squeezed power- 

 fully, the needle moved in one direction, and when the other 

 conductor was squeezed, the needle moved in the same or in 

 an opposite direction. 



It is indispensable to repeat these experiments several times, 

 without which we should be liable to errors. Thus it happens 

 that the deflections of the needle occur alternately in one and 

 the other direction ; but on multiplying the experiments, we 

 find that the deflections frequently take place in the same di- 

 rection, although the compression is produced first by one and 

 then by the other arm. If the chemical action was regular 

 like that of a watch-spring, we ought to obtain currents in the 

 opposite direction. We only experimented in this way, be- 

 cause, on the one hand, we were unacquainted with M. Rey- 

 mond's method of proceeding ; and on the other, we thought 

 that silver, and especially gold and platinum, when simply 

 held in the hand without any compression, would only afford 



