Magnetic PerincabiKty of various Alloys of Iron. 



117 



The effect on magnetic hardness produced by different percentages of various 

 metals added to iron is shown in fig. 12, where the oi'dinates represent coercive 

 force and the abscissae percentages of the added element. The steady rise in the 

 case of the tungsten steels is noticeable. The wonderful softness produced by the 

 addition of silicon to steel is not shown in fig. 12, but will be referred to presently. 



Per ■ oaTt, t a^ g s of acLdad' el-errvcrvt^ 

 Fig. 12. 



The addition of chromium to aluminium steel has the efl'ect of hardening it, 

 and, therefore, injuring the valuable magnetic properties of a pure aluminium 

 steel. Aluminium and chromium have, therefore, opposite effects on steel 

 magnetically. 



Table XII. — Chromium Aluminium Steels (Plate VIII.). 



82 



