Current- Strength on the Conductivity of Electrolytes. 377 



measuring its damping effect upon electric oscillations. The 

 method is obviously one which will apply to electrolytes also, 

 provided that the resistance to be measured is less than 

 twenty ohms ; and it seemed to be very well worth while to 

 determine if the intense current involved in the discharge of 

 a large condenser is capable of causing any change in the 

 condition of an electrolyte. 



In our first experiment, two copper plates of sixteen square 

 centimetres area were clamped at a distance of three centi- 

 metres apart by means of vulcanite. Upon being immersed 

 in a saturated solution of pure cupric sulphate at 15° C, the 

 plates allowed about ten oscillations from one of our large 

 leyden-jars, nine from two jars, and eight from three jars to 

 pass through it. According to the scale of standards, given in 

 our last paper (see fig. 2, p. 355), each of these results corre- 

 sponds to a little less than four ohms' resistance. By means 

 of Kohlrausch's method, using a very small inductorium, this 

 cell gave an extremely poor minimum at a point corresponding 

 to a resistance of about ten ohms. The plates, which had 

 purposely been left very dirty, in order to test the efficiency 

 of the method, were now scrupulously cleaned with alkali and 

 acid, and were then both carefully plated with pure copper. 

 With Kohlrausch's method the cell now gave an excellent 

 minimum at exactly four ohms' resistance, and further clean- 

 ing and plating caused no further change. New photographs 

 of the sparks from the two jars sent through the cell showed 

 again about nine half-oscillations, corresponding to about .3*8 

 ohms. It is evident, then, that the resistance of concentrated 

 cupric sulphate is not essentially altered by great alterations 

 in the strength of the current. 



Experiments with zincic sulphate gave similar results, and 

 a solution of cadmic sulphate between cadmium electrodes 

 which possessed a resistance of 4*7 ohms according to Kohl- 

 rausch's method, gave nine, seven, and six half-oscillations 

 with one, two, and three jars respectively, corresponding to 

 about 5 ohms in each case. 



Undoubtedly the reason why the strong instantaneous cur- 

 rent, which alters so much the resistance of gases, has so 

 little effect upon solutions, is because of the great mass and 

 specific heat of the material which must be warmed in the 

 latter case. The average temperature of the solution rose 

 during our experiments only at the rate of about 1° in three 

 minutes. 



A similar, although smaller, heat-capacity prevents the 

 wire resistances which are used as standards from becoming 

 seriously altered in resistance by the heat. We had used 



