140 PROCEEDINGS OP Till: AMERICAN ACADEMY. 



nitrate, hence any possible error must have crept in during the 



i 



The of flaws in the working of tin' silver voltameter is no 



new idea, and a brief resume of earlier an< ry in oi 



to indicate oar own train of thought. 



Lord Rayleigh and Mrs. Sidgwick found that large cathodes yielded 

 higher results than small ones, and warm solutions yielded higher 

 thau cold ones. In Borne cases the deviations am.innt.-il to ".1 per cent 



Schuster and Crossley* state that deposits made in a vacuum arc 

 Blightlj heavier than those produced by the same current in air, and 

 these in turn arc heavier than those produced in an atmosphere of 

 oxygen. Myersf verified these statements. Schuster and Crossley 

 bin. wed also that with great current density argentic peroxide may form 

 at the anode, ami in sum., unexplained fashion the result is a diminution 

 of the weight of the silver deposited ; moreover, they pointed out the 

 tact that the discrepancies observed l>\ Lord Rayleigh and .Mr.-. Sidgw 

 between large and small howls disappear when the anodes arc of the 

 same size. Apparently "the anode gives /'/*<■ /<> secondary reactu 



Rodger and Watson $ observed that on continued use of the electroh:.- 

 the deposits grow heavier; and they also found that, when a wry strung 

 slightly acidified solution of argentic nitrate was electrolyzed by a 

 powerful current, the acid was removed, and the deposit was much tOO 

 heavy. They venture to say that a subsalt of silver is formed " havii 

 silver ion heavier than the argentic salt." 



Again, Kahle § has found that after boiling the electrolyte with oxide 

 of silver, the deposit is increased ~> parts in 10,000. In a later and \. ry 

 important paper || he calls attention tor the fit-; time to the fact that in 

 a dilute electrolyte an acid is formed during tic electrolysis. Further- 

 more, he shows again that old solutions give too high resnlts. an error 

 which was sometimes removed by treatment with argentic oxide. 

 Colored -pots sometimes appeared upon the silver in old acid solutions. 

 apparently caused by the liquid descending from the anode; the.-,' did 

 not form in a neutralized Bolution, or in one which had been allowed to 

 remain in contact with silver. Kahle's hypothetical explanation of li 

 phenomena essentially agrees with Rodger and Watson's. 



i'r.w. i;,, v . Soc, 50. ::lt (1892). 

 t Wied. Ann., 55, 288 (1896 

 } Phil. Trans., 186 A, 631 (1895). 

 § Brit. A.88. A U Sc. Edinb. ( 1892), ]>. 1 18. 



Wied. Ann., 67, 1 (1899), or Zeitscb. f. [nstrkunde, 18. 229, 267 (1898). 



