LENZ ON ELECTRO-iMAGNETISRl. 621 



current produced by its removal is directly as the diagonals of the 

 wires ; for the electromotive power remains the same, but the resist- 

 ance it experiences in being conducted decreases inversely as the dia- 

 gonals ; consequently the electric currents, or the quotients of the elec- 

 tromotive powers by the diagonals, increase as the diagonals. 



IV. On the Influence of the Substance of the Wires on the Electro- 

 motive Power produced in the Spirals. 



Nobili and Antinori have in their first paper on the electrical phae- 

 nomena produced by the magnet (PoggendorfF's-4M«a/en, 1832, No. 3) 

 already determined the order in which four different metals are adapted 

 to produce the electric current. They arrange them in the following 

 order, — copper, iron, antimony, and bismuth. 



It is particularly striking that this order is the same as that which 

 the above metals occupy also in reference to their capacity of conduct- 

 ing electricity ; and the idea suddenly struck me whether the electro- 

 motive power of the spirals did not remain the same in all metals, and 

 whether the stronger current in the one metal did not arise from its 

 being a better conductor of electricity than the other. With this view, 

 therefore, I examined four metals, namely, copper, iron, platina, and 

 brass, and pursued the following course : In order to avoid entirely the 

 influence of different conduction, I brought at the same time into the 

 metallic conducting circle through which the electric current had to 

 pass, two spirals, equal in all respects excepting that they were of dif- 

 ferent metals, binding the one end of the first with the one conducting 

 wire, the one end of the second with the other conducting wire, and 

 connected the two ends of the spirals which had remained free with a 

 distinct copper connecting wire. I now brought first the one spiral upon 

 the iron armature of the horseshoe magnet, and proceeded in the same 

 way with it as in the former experiments, and then the other. In this 

 manner the resistance which the electric current suffeied in each pro- 

 cess was naturally quite the same. — I must also remark that I carefully 

 avoided all thermo-electric disturbing forces, as I surrounded the places 

 of connection of the various wires with several layers of blotting-paper, 

 and after having arranged the apparatus I always waited several hours in 

 order to give the places of connection time to take tlie temperature of 

 the room. 



The experiments themselves are as follows : 



