Fiske and Collins — Surface Travel on Electrolytes. 59 



Akt. X. — Surface Travel on Electrolytes ; by W. E. Fiske 

 and W. D. Collins. 



To investigate the availability of Ohm's law for electrolytes 

 when in circuit with alternating currents, has been the object 

 of frequent research. The following are references to articles 

 by Kohlrausch having a bearing on the subject : Pogg. Ann., 

 cxxxviii, p. 370 ; Wied. Ann., vi, p. 1 ; xxvi, p. 164. Also in 

 Wied. Ann., xxi, p. 667, E. Cohn gives an elaborate treatment 

 of the matter. All these investigations showed that Ohm's 

 law held in nearly every case, the only exception being that 

 polarization at the electrodes seemed to increase the resistance 

 slightly when the current was of a frequency as low as 100 or 

 less per second. In view of the fact, however, that this work 

 was in no case carried on with a current alternating more than 

 25,000 times per second, it seemed worth while to examine the 

 resistance of an electrolyte to a current of much higher fre- 

 quency. 



The following work was carried on under the direction of 

 Professor Trowbridge. 



The method used was practically that described by Professors 

 Trowbridge and Richards in an article in this Journal (vol. iii, 

 p. 327, April, 1897). The electrolyte replaced the tubes of gas, 

 and its resistance, together with that of the wires used for the 

 standard, was measured with an alternating current. 



The electrolyte, a saturated solution of copper sulphate, was 

 contained in a tank a meter long and a square decimeter in 

 cross-section. The electrodes were of sheet copper equaling in 

 area the cross-section of the tank. The distance between them 

 could easily be altered so as to give a column of variable resist- 

 ance. 



The plan followed was first to measure the resistance of a 

 certain length of the solution on a Kohlrausch bridge. Next, 

 with the solution in series with the spark gap, a photograph of 

 the spark was taken, and the number of half oscillations corre- 

 sponding to the length in question was plotted against its 

 ohmic resistance. This was done for lengths of the solution 

 of resistance varying from 6 to 24 ohms. The solution was 

 then replaced by manganine wires of different lengths, and the 

 operation repeated. These wires were 0*3 mm in diameter and 

 stretched on both sides of thin vulcanite plates in order to 

 eliminate self-induction. The curves thus obtained were then 

 compared. 



The result is shown in the four accompanying figures. Here 

 ohms are plotted horizontally and half-oscillations vertically. 



