525 



order of magnitude 10—^; silver is diamagnetic and does not become 

 supra-conducting at helium-temperatures. 



As appears from the table, it was found that with silver also the 

 HALL-effect increases, when the temperature falls to 4.°25 K. At 

 still lower temperature it does not show any further change, no 

 more than the resistance without a tield. 



3. A bismuth-plate Blym. moulded from electrolytic bismuth- 

 powder. Bismuth has a verj high HALL-effect at hydrogen-temperatures 

 and the change from 20° K. to 14° K. is still very small. It is the 

 strongest diamagnetic metal. 



The table shows that below 'i4o K. there is not much further 

 change in the HALL-effect. From 71 at 20° K. R rises only to 85 

 at 4°.25 K. 



4. X nickel plate as representative of the ferro-magnetic metals. 

 With nickel at higiier temperatures the HALL-effect shows a tendency 

 to saturation owing to the nuignetisation of the metal (Comm. No. 129, 

 130, 132). At hydrogen-temperatures the effect is still easily measu- 

 rable; at helium-temperatures it disappears, although the resistance 

 of the plate is still considerable. Probably this is connected with the 

 fact, that notwithstanding the already fairly considerable field the 

 magnetisation of the nickel is still very small. 



The results are collected in table V. (zie p. 577). 



^ 6. Change of the resistance in the magnetic field. It was found, 

 that specially at helium-temperatures this change is very con- 

 siderable, but that at 20° K. also it is still quite well measurable. 

 In general there is a diflference between the longitudinal and the trans- 

 verse effects, which begins to show itself especially clearly at helium- 

 temperatures. 



We shall give our results in the form of curves (figs. 1 to 6) on 

 which the numerical values may also be read with suflicient accuracy 

 by using the scale-values indicated in the figuj'es. So far the meas- 



If oca 



Fig. 1. 



