M. E. Edlund on the Nature of Galvanic Resistance. 205 



acquainted. Moreover it will subsequently be shown that, 

 although the proposition here advanced is contrary to the 

 general view, it is in no way inconsistent with the experimental 

 evidences on which it has been supposed that view could be 

 founded. 



Conformably to experiment and the above theoretical conside- 

 rations, we obtain the following as the expression for the resist- 

 ance r in a conductor of length 1 and cross section a when the 

 current s passes through it : — ■ 



7 s 

 r = k- =r ft .9, 



a ° ' 

 where k is a constant dependent on the temperature and on the 

 physical and chemical constitution of the conductor. The con- 

 stant k is evidently the resistance of a conductor whose cross 

 section is 1, and its length 1, when it is passed through by a 

 current of intensity 1. 



s 



- is the current-intensity on the unit of surface of the cross 



section ; r , or what has been hitherto named the galvanic resist- 

 ance, is simply the resistance for the unit of intensity of the 

 current. 



3. We now imagine a closed circuit whose length is I, and its 

 cross section everywhere a, and which consists throughout of the 

 same material and is passed through by a constant current with 

 the intensity s. If 8 is the mass of aether in motion in the unit 

 of volume, and h its velocity, s = a8h. To calculate the mecha- 

 nical work performed by this current in the unit of time, let us 

 first consider separately a current-element whose length is 1. 

 Because the counterpressure on the unit of surface of the cross 

 section is r, and the magnitude of the section a, the counter- 

 pressure on the whole of the cross section becomes ra = ks. In 

 the unit of time this element is moved forward the distance h ; 



wherefore the work done will be ksh. Now h is = —k 3 in which, as 



was shown above, 8 is constant. The mechanical work, for this ele- 

 cta 2 

 ment, thus becomes — k-. Multiplying this expression by /, we 



kls 2 

 get the work of the whole current, = -k-. When, finally, this 



is multiplied by the heat-equivalent A of the unit of work, and 



the constant 8 is combined with k, we obtain the quantity of 



KkW 2 

 heat produced by the current in the unit of time, = , a 



result which, as is known, agrees with experiment. 



According to the same principles the calculation can be easily 



