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PROCEEDINGS OP THE AMERICAN ACADEMY. 



oxide-complex, may explain many of the irregularities observed during 

 the electrolysis, they cannot explain them all. The chief questions re- 

 maining to be answered concern the cause of the high results which are 

 still to be obtained when all the preceding causes of irregularity have 

 been eliminated, as well as the mechanism of the formation of the plentiful 

 " anode dust." 



A number of facts point to the conclusion that some other complex 

 compound exists in the electrolyzed liquid which is capable of deposit- 

 ing metallic silver upon a silver surface. Among others is the well 

 known fact that a pure silver kathode receives a larger deposit with a 

 given current than a platinum kathode in the old Lord Rayleigh vol- 

 tameter. It seemed to be worth while to test once more this relation, in 

 order to confirm the results of Lord Eayleigh, Kahle, and others, and 

 also to discover if a pure argentic nitrate solution in the porous cup 

 voltameter would give like results. The following tables record the 

 results of our experiments. In the first place we repeated Kahle's ex- 

 periments, using an anode protected only by filter paper. 



TABLE VII. 

 Filter Paper Voltameter os Platinum and on Silver. 



There is an undeniable surplus when the deposit is made on silver. 

 The main question now arises, — Is this effect due to the anode solution, or 

 is it an irregularity which would come equally from pure argentic nitrate ? 

 The answer to tlie question is easily determined by means of our porous 

 cup ; a comparison of deposits made in a standard voltameter on a silver 

 and a platinum kathode gave the following results : — 



