Certain Chrome and Tungsten Steels. 



745 



steels I used, and her work shows (see Table III.) an improve- 

 ment in magnetic moment with increasing percentage of 

 chromium beyond the percentage found to be best by 

 Brown. 



Table III. 



Percentage of Chromium. 



Magnetic moment per gm. 



2-486 



59 



2-831 



64 ' 



3-445 



68 



A general comparison between the behaviour of the steels of 

 different dimension-ratios as shown in Tables I., II., and III. 

 suggests, therefore, that while a fairly high percentage of 

 chromium gives the most satisfactory magnet where the 

 dimension-ratio is about 20, smaller percentages of chromium 

 are desirable if the dimension-ratio is to be increased. 



It was mentioned earlier that certain other processes, pro- 

 Ion ged gentle heating for instance, had also the effect of 

 hastening the settling down of the magnet into a permanent 

 condition ; but as the tests already carried out gave a fairly 

 good idea of the permanence of the magnetism, it was 

 decided not to carry the maturing process any further, but 

 rather to examine the effect of the same treatment upon 

 another series preferably of more highly magnetic steels, 

 and the graded series of four tungsten steels whose com- 

 position is given in Table IV. below was accordingly obtained 

 from Sir W. G. Armstrong, Whitworth & Co., Ltd. 



Table IV. 



Specimens. 

 A 





Percentage composition. 





Carbon. 



Tungsten. 



Manganese. 



0-44 

 0-43 

 043 

 043 



2-88 



5-85 



8-72 



11-65 



0-24 

 0-26 

 0-25 



0-26 



B 



C 



i D 



i 



Phil. Mag. S. G. Vol. 28. No. 1(57. iVov. 1914. 3 C 



