430 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



In an atmosphere of nitrogen an excess of .05 per cent in the deposit 

 was observed. Our own experiments in the same direction verify the 

 results of these experiments, and need not be recorded here. 



Putting aside for the moment the question concerning the nature of 

 the irregular compound which can thus be partly oxidized out of exist- 

 ence, it seemed worth while to discover if an oxidizing a<jent in the 

 solution could remove this compound to such an extent as to cause the 

 filter paper voltameter to yield accurate results. The only practical 

 oxidizer for this purpose is hydrogen peroxide. A fairly strong solution 

 was prepared from pure crystalline barium peroxide and dilute sulphuric 

 acid. The excess of acid was removed with barium hydroxide, and the 

 solution was filtered. In this solution the usual amount of silver nitrate 

 was dissolved, and this was used in the large bowl as well as in the lipped 

 crucible, both anodes being wrapped in filter paper. In the large bowl 

 black crystals of argentic peroxide, or Ag 7 NO n , were soon formed 

 which bridged across to the kathode. While the result in the bowl thus 

 became useless, the crucible showed no such disturbance, but yielded 

 nevertheless a deficit of .14 per cent on comparison with a standard. 

 This must have been due to a side reaction, especially since the kathode 

 was found covered with small gas bubbles, which were probably oxygen. 

 It is possible that negative electricity was carried from the kathode to 

 the solution by the ionizing of a trace of oxygen. Better results were 

 obtained after the hydrogen peroxide had been diluted to one-tenth its 

 former strength ; these are recorded below: — 



TABLE IX. 



Standard vs. Filter Paper Voltameter containing H.,0 9 . 



The usual difference of from .04 to .08 per cent is thus reduced to 

 .025 per cent ; therefore hydrogen peroxide seems to eliminate a part 



