1895.] Conductivities of Badly Gondiicting Substances. 261 



dx 

 di 



ChOO 



(^) by -Ti and integrate ; we get 



when x^ denotes the initial value of x. 

 We get from (4) and (5) 



Ad(~\\e'x: 





BD - AE 

 dt 



(ajCG 



Since initially -^ and y both vanish, we get from (1) and (2) 



d^x\ _ N Xq 

 df), ~~~GA' 



d^x\ 



(d x\ ^ 

 -T^ ) we find 



LN-M' ^ 



r /(I^tV t^ Lis — IVr 



\{^\dt-^-^ '^ I ...(6). 



J \atj o ^:^R^LS){^~ + SRy{LN-M')'^ 



The expression on the right-hand side of the equation is least 

 when 



If, as in the following experiments, RG is small compared with 





A/-(-f)' 



we have 



Now NfS is the time constant of the secondary circuit when 

 alone by itself in the field, while 



\/^(^-f) = =^/2^' 



