Dr. E. Bouty on the Magnetization of Steel by Currents. 197 

 Bars not saturated, 10 millims. in diameter, not hardened. 



Length. 



Teinporai-y magnetization. 



Permanent magnetization. 



Observa- 



Calcula- 



Differ- 



Observa- 



Calcula- 



Differ- 





tion. 



tion. 



ence. 



tion. 



tion. 



ence. 



centiru. 















11-6 



2-60 



2 121 



+ 0-479 









150 



3 63 



3-828 



-0-198 









192 



6-68 



6-712 



-0032 



1-223 



1-198 



+0025 



245 



11-47 



10540 



+ 0-930 



2-573 



2-357 



+0-216 



29-4 



16-17 



15-520 



+0-650 



4-149 



3-781 



+0-368 



34-5 



21-75 



20362 



+ 1-38S 



5-233 



5-659 



-0-426 



39-4 



23-44 



25-090 



-1-650 



7571 



7-788 



-0-217 





A —0-9966 B — 1 



A —0*793! "R - 





1 7-142" 





"' ~ 2 17-857' 



The results furnished by steel not hardened, to which the 

 preceding Tables relate, are particularly interesting. 



In the first place, the coefficient B is independent of the in- 

 tensity of the magnetizing current. A determined value 



Bl= 7Ti2 



corresponds to the temporary magnetism ; to the permanent 

 magnetization corresponds a much smaller value, 



1 



B,= 



17-857 



This coefficient does not vary with the diameter of the bars. 

 It is easily seen, on making x very great in formula (1), that 



7j = -d represents the distance of one pole from the neigh- 

 bouring extremity in long bars. For a=l centim. we have 

 1 ,. 1 



A 



7*142 centims., -~- =17*857 centims. ; 



H2 



and these polar distances are characteristic of the steel used — 

 the one for the temporary, the other for the permanent mag- 

 netization. 



Secondly, the coefficient A 1? which is referred to the tem- 

 porary saturation, is greater than the coefficient A 2 , corre- 

 sponding to the permanent saturation. In general A 1 and A 2 

 are functions of the intensity of the magnetizing force not dif- 

 ferent from those which we have studied in sections I., II., 

 and III., under the name of functions of temporary and per- 

 manent magnetism. But the experiments on bars have not 



