900 



Mr. C. W. Heaps on the Effect of 

 Table II. 



Glass. 



2 -(T(^+c\). 



3. Ph. R 



8. Bl. R. II 



-1-35 



-2-89 

 -210 

 -2-47 

 -3-78 

 -3-56 



7. Bl. E.I 



10. 477 m R. II 



12. D. F. R. II 



16. L. F. R. II 





kinds of glass ; for the others, the changes in capacity, and 

 hence the quantity S 2 — o-(o\ + S 2 ) is so small that very small 

 experimental errors would have a large effect in the deter- 

 mination of it. 



LXXXVI. The Effect of Magnetic Fields on Metallic 

 Resistance. By C. W. Heaps *. 



[Plate XVI.] 



NUMEROUS investigations have been made on the change 

 of resistance which different metals undergo when they 

 are placed in a magnetic field. Some experimenters have 

 taken up the case where the magnetic field is applied parallel 

 to the direction of the current in the metal, and others have 

 studied the effect when the field is perpendicular to the 

 current. This latter transverse effect has been most com- 

 pletely worked out for different metals by Grnnmach f. The 

 longitudinal effect is not so thoroughly understood, because 

 it is more difficult to use a large magnetic field in this case, 

 and hence the change of resistance to be measured is very 

 small. Williams {, using a solenoid, has studied nickel and 

 iron for small longitudinal magnetic fields. Barlow § , 

 Patterson ||, and Owen \ have employed an electromagnet 

 and so obtained results for large magnetizing forces ; but 

 the uncertainty or incompleteness of these results makes a 



* Communicated by Prof. E. P. Adams. 



f Annate n der Physik, xxii. p. 141 (1907). 



% Phil. Mag. vi. p. 693 (1903); ix. p. 77 (1905). 



% Itoy. Soc. Proc.lxxi. p. 30 (1902). 



|| Phil. Mag. iii. p. 643 (1902). 



% Phil. Mag. xxi. p. 122 (1911). 



