Thin Metal Partition in a Voltameter. 

 Thickness of Partitions. 



191 



Platinum. 



«1 

 *2 

 »3 



*4 



*6, 



millim. 

 S. & W. ; pure; =0-1. 



„ ; „ ; =0-002. 



M. ; „ ; =0-000152. 

 S. & W. ; „ ; =0-0173. 



„ ; „ ; =0-00407. 



Gold. 



Silver 



81 ; S. & W. ; pure ; =0-0023. 



Aluminium. 



%\ ; commercial ; 



#2 ; „ ; 



=0-4. 



= 0-00051. 



»0; 



S. &W. ; 



pure ; 



11 J 



M. 



j> j 



#2; 



>> 



. 92ft . 

 5 1000 ' 



#3 



i j> 



) >> > 



#4 



>> 



i » J 



#5 



jj 



i JJ > 



#6 



> j> 



I >> > 



»7 



j >> 



5 »» ! 



millim. 

 =0-25. 



=0-0472. 



=00241. 



=0-00433. 



=0-00183. 



=0-000586. 



=0-000382 



=0-000087. 



The series of gold plates is fairly complete. They were 

 beaten to order by Ferdinand Miiller in Dresden. Effort 

 was made to get a similar series of platinum ; but as platinum- 

 foil for " silvering " seems to have fallen into disuse, I was 

 unable to find anyone prepared to make it for me. This is 

 unfortunate, as platinum is the only metal which seems to 

 remain free from chemical action under a strono- and lonp> 



IL I J. 



continued electric current. However, as $ 2 and f 3 of the 

 platinum happen to fall below and between the critical limits 

 respectively, they serve as a very important check upon the 

 results obtained with the more complete gold series, and show 

 that these results are at least qualitatively correct. Below will 

 be found reasons for believing them to be quantitatively correct. 

 In the Tables which follow, 



I = current, in amperes, passing through the voltameter; 

 x = polarization, in volts, on the metal partition ; 

 v = ohmic resistance of the voltameter, partition open. 

 Table I. was obtained with the old voltameter. 

 The results in Table II. were obtained with the new volta- 

 meter without leakage. The readings were taken after 

 waiting two minutes for the current to become steady when 

 a new plate was inserted, or the resistance changed for a new 

 current-strength ; and in case of the thicker plates, where 

 the time-change in the polarization was more pronounced 

 and continued longer, five to ten minutes was allowed between 

 readings, or in each case until the galvanometer indicated 

 that the current had become about constant. Later tests 

 given in another table show that this time-change of polari- 

 zation, especially for thick plates, though at first rapid and 

 then very slow, really continues some time. 



