298 Mr. J. Daniel on the Polarization upon a 



Table VI. 



Showing the increasing Critical Current of 0*02 millim. 

 Palladium in a 30 per cent, solution of H 2 S0 4 . 



Date. 



Jan. 31 



>> >> 



Feb. 4 



„ 8 



» 17 



j> >> 



„ 18 



Current. 



Current-density. 



-I - 



0-08 

 010 

 0-15 

 0-17 

 0-25 

 0-26 

 0-27 

 0-27 



0-045 



0-057 



0-086 



010 



014 



015 



154 



0154 



After much use. 



A new specimen of the same palladium is being tested and 

 is showing the same phenomenon of increase of the critical 

 current. This last specimen was carefully selected and has 

 no holes. Its critical current at first was 0*016 ; after some 

 use it is now 0*043. 



I have begun to use a solution of sodium acetate with the 

 hope that it will not oxidize the gold. I can already say that 

 it is at least very much less active than sulphuric acid ; it also 

 shows a decided temperature coefficient for the critical current. 

 This part of the investigation will be resumed when oppor- 

 tunity offers. 



Vanderbilt University, Nashville, Tennessee, 

 February 22, 1893. 



Note added April 15, 1893. 



More satisfactory specimens of palladium have not yet been 

 obtained, so the matter is left for the present with the seem- 

 ingly anomalous results recorded above as I find in my 

 note-book. 



As regards the temperature coefficient of the " critical 

 current-density," I requested Mr. R. W. Clawson, a student 

 in the laboratory, to make some measurements which are 

 tabulated below. 



It may be well to state that the method of observation, that 

 of observing the first appearance of visible gas, is not very 

 sensitive, because this development of gas on thin partitions 

 is not quite sudden and sharply defined, bul begins gradually, 

 especially with very thin partitions. The probable error of 





