523 



TABLE IV. 



§ 5. Tke JiAhL-efect at kelium-teinperatures. The method was the 

 same as in the previous measurements. To check the results, measure- 

 ments were made both witli the compensation-apparatus and with 

 the differential-galvanometer. Five different plates \vere experimented 

 upon in the helium-batli. These were chosen so, that they could be 

 regarded as representatives of metals for which the HALL-effect is of 

 a different type. Each set of six wires from the six electrodes of 

 one plate was completely separated from the otlier sets in the cryostat. 



The following plates were investigated. 



1 , A tin and a lead plate : both metals are supra-conducting at 

 extremely low temperatures. Lead remains supra-conducting up to a 

 considerable threshold-value of current. It may be added that both 

 are diamagnetic : as be Haas has shoAvn, the diamagnetic properties 

 are of great importance for the HAJ.L-effect. 



At hydrogen-temperatures the HALL-effect is still so small, that it 

 escapes observation. It was found that at 4°. 25 K. both with tin 

 and lead the effect can be very well measured, when the tield is 

 so high, that ordinary resistance is generated in the metals. As long 

 as the field is low enough for the metal to remain supra-conducting, 

 the HALL-effect, like the ordinary resistance, disappears. 



2. A silver plate, as representative of the grouj) of metals for 

 which at the ordinary temperature the HALL-coeflicient is of the 



