144 Messrs. Gee and Holden on 



had it formed than it began to disappear again, and did not 

 reform until the circuit had been broken. On making the 

 gold wire the anode, after the current had been in the previous 

 direction, it was noticed that one of two things happened, 

 either (1) the deflection at first was large, and decreased 

 rather quickly to a small value, then increased gradually to 

 its former value, or (2) the deflection at first was small and 

 then made a sudden jump to a high value, at which it remained. 

 The gold wire used was very rapidly eaten away. 



4. Experiments with other Electrolytes and Platinum 

 Electrodes. 



a. Phosphoric Acid. — Efforts to produce a definite film have 

 been unavailing. We have tried various solutions (including 

 some quite viscous), and although we have found that there 

 is a difference of deflection in the two directions of the 

 current, the electrodes being a point and a plate, we are dis- 

 posed to attribute this mainly to polarization. At the same 

 time there certainly is evidence of a difference of transition 

 resistance in the two directions, for in one case, using a 

 battery E.M.F. of about 18 volts, the deflection when the 

 point was anode was double that with the current reversed. 

 This indicates that in the latter direction there is a higher 

 transition resistance, for any difference of polarization in 

 the two directions would probably be small relative to 

 the E.M.F. employed. 



b. Caustic Potash. — Different strengths of solution up to 

 saturation, and a battery E.M.F. up to ten volts were used, 

 but no definite film could be obtained. On adding glycerine 

 to the solution, in order to increase its viscosity, the transition 

 resistance, as measured by Ohm's method, was greater with 

 the point anode than when kathode ; in one experiment the 

 resistances were 37 and 3'5 ohms respectively. Attempts 

 were afterwards made to repeat the effects obtained by Ohm, 

 with solutions of caustic potash, and for this purpose a battery 

 of 3 Daniells was employed. The differences of the de- 

 flections in the two directions, and also the fall of the 

 deflection obtained after making circuit, were generally to be 

 attributed to polarization; but using certain currents a 

 tendency towards the formation of a transition resistance 

 could be traced, as evidenced by the table below, the numbers 

 of which were obtained by Ohm's method. 



