on the Corbino Effect. 697 



and the results obtained follows. The radial current was 

 usually about 12 amperes. In every case there was found 

 to be exact proportionality between the circular current 

 produced and the radial current. By n we shall denote one- 

 half the difference between the balancing inductance for a 

 positive and negative magnetic field. 



Copper* — The disk was cut from a sheet of commercial 

 copper. The circular current had the direction correspond- 

 in o- to free negative electrons. The effect was too small to 

 make certain any variation from proportionality between the 

 •circular current and the magnetic force. The results obtained 

 are given in the following table. Each number represents the 

 average of several determinations. 



7313 



40-6 



11 

 180 



6747 



39-8 



169 



5923 



36-4 



162 



4223 



23-8 



177 



2817 



22-1 



128 





Average . 



.. 162 



Owing to the smallness of the effect the numbers for the 

 smaller fields are rather uncertain. 



To make sure that the effects obtained were not influenced 

 by possible thermoelectric currents arising from the employ- 

 ment of two different metals, copper and brass, the experiment 

 was repeated with a copper ring replacing the brass ring and 

 a slit copper plate replacing the brass plate. The results 

 obtained were the same within the limits of experimental error. 



Iron. — The iron disk was cut from a bar of Norway iron. 

 The effect was opposite in sign to that of copper, and con- 

 siderably larger as shown below. Here again there was no 

 certainty of any departure from proportionality between the 

 circular current and the magnetic force. 



H 



H. 



8446 



n. 

 141 



n ' 

 60-0 



7622 



118 



646 



6747 



104 



64-8 



4893 



76-2 



64-2 



3296 



50'8 



64 '8 



2060 



39-8 



51-8 



1390 



24-3 



57-2 



Average ... 011 



Phil. Mac,. S. 6. Vol. 2S. No. 167. Nov. 1914. 2 Z 



