Hall and Corbino Effects. 307 



the disks investigated. The radial current in every case was 

 about twelve amperes, and the value of m/H for each field 

 is the mean of a number of determinations. One-half the 

 difference between the balancing inductance readings for 

 positive and negative fields is denoted by m. 



The Corbino Effect in Copper. 



II. 



m. 



m[K. 



cxlO 7 . 



2590 



12-1 



00469 



2-11 



4280 



199 



0-00465 



2-09 



6130 



320 



0-00522 



2-35 



7590 



39-8 



0-00524 



2-36 



8490 



37-5 



0-00442 



1-99 



2510 



121 



0-00484 



248 



4060 



18-8 



0-( 10462 



2-08 



5890 



28-7 



000481 



2-17 



7450 



34-2 



0-00460 



2-07 



8530 



431 



00505 



2-27 



II 



Summarizing :■ 



Field. 



m/R. 



2500 

 4200 

 6000 

 7500 

 8500 



Mean 



0-00476 

 0-00463 

 0-00501 

 0-00492 

 000473 



000481 



= 1/208 



Meanc = 2-17xl0- 7 . 



It will be observed that the values of m/H for the five' 

 fields do not depart by more than 4 per cent, from the 

 mean, so we may say with safety that the value 7?i/H = 1/208 

 is accurate to 2 per cent. There is no evidence of any 

 variation of ???/H with the field. 



Bismuth. — Two disks, from the same body of metal, were 

 cast to exact size in graphite moulds; one for the Corbino 

 effect and one for the Hall effect. The specific resistance, 

 determined by the method above, was found to be 1572 x 10 ~ 7 r 

 while the value used for copper is 17 x 10~ 7 . 



