Free Ions in Aqueous Solutions of Electrolytes. 247 



was too low to decompose the water ; hence it would seem 

 that there are free ions present and that they are heaped up 

 around the electrodes when they are charged by a Daniell. 



Some time after the preceding experiments the following 

 were performed. 



It is known that when two metal electrodes, as for example 

 copper, are placed in a solution of their salt and the circuit 

 closed, that the smallest potential difference between them will 

 give rise to a current and the metal will be dissolved from the 

 anode and deposited on the cathode. 



If then we take two copper electrodes, weigh them carefully 

 and they on being placed in a solution of copper sulphate do 

 not give too decided a deflection, we may be able to change the 

 direction of the deflection by an electrostatic charge and then 

 on short circuiting them and keeping up the charge we should 

 get a diminution in weight of the anode and a gain in weight 

 of the cathode. 



Copper wires were bent into a flat zigzag form, in order to 

 give a larger surface exposed and at the same time so that 

 they might be placed near to the edge of the cell and conse- 

 quently as near as possible to the electrostatic charge. 



The electrodes were marked, cleaned in nitric acid, washed, 

 dried and carefully weighed. The electrodes on being placed 

 in the solution gave a decided deflection, but I was able to 

 reverse this direction with two ordinary sized Leyden jars 

 connected to a disk of an electrophorus and charged by a fric- 

 tion machine. The circuit was then closed through the galva- 

 nometer, and the electrostatic charge renewed occasionally by 

 giving the electric machine a few turns. If the circuit was 

 closed without any external resistance as by a short thick wire, 

 the cell ran down quickly and sometimes gave a deflection in 

 the opposite direction, so the circuit was made through the 

 galvanometer. The circuit was kept closed for about three- 

 quarters of an hour, breaking it only while recharging jars. 

 The electrodes were then taken out, washed with distilled 

 water, dried, and again weighed. It was found that the 

 cathode had gained about 1-2'°^°' and the anode lost about O'-i'"^"'. 



It had been found throughout these experiments that the 

 negative charge was not as effective as the positive, which is 

 perhaps due principally to its wasting faster than the positive. 

 However, having four Leyden jars connected to the disk so as 

 to hold the charge longer, I found the negative charge the 

 more effective, and the direction of the deflection would often 

 be reversed at the flrst observation taken after charging. The 

 first observation was not generally taken until about 10 min- 

 utes after charging so as to allow the induction to disappear. 

 Having reversed the direction with a negative charge, the jars 

 were discharged. Now leaving everything as before but 



