150 Mr. H. A. Rowland on Magnetic Permeability, 



Results 



















given 

 in 



Quality of 

 substance. 



How made. 



Temper. 



Spec, 

 grav. 



Weight. 



Mean 

 diam. 



Area. 



State. 



Table 



















H 



" Burden's 

 best ° iron. 



Welded and 

 turned. 



An- 

 nealed. 



J7-63 



148-61 



0677 



•0000 

 916 



Normal. 



ii. 



a tt 



tt tt 



tt 



7-63 



148-61 



•0677 



916 



Magnetic. 



in. 



tt a 



tt tt "j 



C an- 

 nealed. 



J7-63 



14801 



0677 



912 



Burnt. 



IV. { 



Bessemer 

 steel. 



Turnedfrom 

 large bar. 



Natural. 



7-84 



38-34 



•0420 



371 



Normal. 



v -{ 



Norway 

 iron. 



Welded and 

 turned. 



C an- 

 nealed. 



17-83 



39-78 



•0656 



7695 



Magnetic. 



VI. { 



Cast 

 nickel*. 



Turnedfrom 

 button. 





8-83 



4-806 



•0200 



0869 



Normal. 



VII. 1 



Stubb's 

 steel. 



Hard-drawn 

 wire. 



Natural. 



773 







0969 



Normal. 



The first three Tables are from the same ring. 



Besides these I have used very many other bars and rings ; 

 but most of them were made before I had discovered the effect 

 of burning upon the iron, and hence did not give a normal curve 

 for high magnetizing-powers. However, I have collected in 

 Table VIII. some of the results of these experiments ; but I have 

 many more which are not worked up yet. 



In the following Tables Q = — ^ has heen measured as pre- 

 viously described. It is evident that if, instead of reversing the 

 current, we simply break it, we shall obtain a deflection due to 

 the temporary magnetism alone. In this manner the tempo- 

 rary magnetism has been measured; and on subtracting this 

 from Q, we can obtain the permanent magnetism. 



The following abbreviations are made use of in the Tables, the 

 other quantities being the same as previously described. 

 C.T.G. Number of coils of tangent-galvanometer used. 



Deflection of tangent-galvanometer. 



Deflection from coil G. 



Deflection from helix F on reversing the current. 



Magnetic field in interior of bar (total). 



Deflection from F on breaking current. 



Magnetic field of bar due to temporary magnetism. 



Magnetic field of bar due to permanent magnetism. 



Number of coils in helix F. 



Q=T + P. 



D.T.G. 

 D.C. 

 D.F. 



Q 



D.B. 



T 



P 



Almost chemically pure before melting. 



