Magnetic Permeability of various Alloys of Iron. 115 
Tastr [X.—(Plate V.) 
Marks. w for H = 8. ere aes | 
Tron 1560 | 11090 
1420 340 36700 
»  Uunann. 210 57300 
1430 A 155 47060 
>  wnann. 0 480 
1450 A 37 19950 
» wnann. 0 550 
The specimen, 1430 A, has nearly 9 per cent. of chromium added to a steel 
containing 8 per cent. manganese, and also very high carbon. Upon referring 
to Tables IV. and V., it will be seen that a corresponding steel without the 
chromium has higher coercive force but lower retentivity, and on comparing the 
respective areas of the curves given in Plates III. and V., the larger hysteresis 
loss in the manganese chromium steel is apparent. This comparison is of the 
annealed specimens; the effect of annealing is seen to be much greater on the 
chromium-manganese steel, which is but feebly magnetic in the unannealed state 
in this field. The large hysteresis loss, shown by 1420 in the wnannealed condition, 
is due to its high coercive force combined with great induction and retentivity ; 
the large area of this curve is seen on Plate V. On referring to Group 2, p. 76, 
it will be noticed that this steel has 0°75 of carbon and 1 per cent. of manganese, 
whereas 4147 has the same percentage of manganese and only 0°24 carbon. 
This small difference in the carbon will be seen to make a great difference in the 
hysteresis loss of the annealed specimens in the two cases (see Tables V., p. 109, 
and IX. above); in the unannealed state probably a still greater difference would 
be found ; the specimen 4147, however, was not tested before being annealed. 
The next Table gives the magnetic properties of all the tungsten steels we 
have examined. 
Taste X.— Tungsten Steels. (Plate VI.) 
Marks. TG | aac on Retentivity. | Coercive force. | « for H = 8. | aoe ye 
Iron sid 0:0 17480 7120 | 166 | 1560 11090 
1294 F He | 16600 8320 3:23 1360 14590 
MEET 5 | 16400 12500 | 5:78 iGO | 25830 
mei qs | 15920 13580 9:02 410 49000 
~ b | 18% 11560 9620 13-92 117 45320 
TRANS. ROY. DUB. SOC., N.S. VOL. VII., PART Iy. Ss 
