Magnetic Permeability of various Alloys of Iron. 121 
Unfortunately, most of the specimens contained in Table XVI. were examined 
too late to have their B and H curves inserted on Plate IX., which contains only 
the first two specimens, 1397 A and B; these also show that a small percentage 
of silicon improves, magnetically, a low nickel steel. As the carbon is low in all 
these specimens (except 803), they may more properly be called silicon-iron alloys 
than silicon steels. 
TasLte X VI.—Stlicon-Iron Alloys. 
Mark Percentage. 
Si Ni | c 
1397 A* 0:44 | — 0:22 
, Be 0°33 | 0°58 | 0:26 
898 E 2°5 | — | 0-20 
| se lal 5:5, | = 0:26 
| 803} 2°25 | = 0:67 
mmenIGTOSHAN 2°0 | 3-25 | 0°38 
| eee 3°25 3°50 0:22 
Tasty XVI.—Stlicon-Iron Alloys (continued). 
Marks. | Moss tndaedan Retentivity. fo adore 135 = GE | Coercive force. 
Tron | 17480 7120 1560 | 1:66 
1397 A 15720 10800 640 7-46 
» B 16940 ~=0|~—s12040 920 7°33 
898 E 16640 4080 1680 0:90 
» il 16480 3540 1680 | 0°85 
803 16000 8320 1345 (| 3°70 
1103A | 16240 | 6990 1120, | 2-00 
» O 15960 7270 | 1280 | 1-90 
The interesting fact is revealed by the above Table that the addition of 2 to 
54 per cent. of silicon to steel, as in the specimens 898 E and H, increases the 
magnetic softness to such an extent that the coercive force and retentivity are 
reduced to nearly one-half that of the standard iron rod, which contains only 
0-03 per cent. of carbon. The permeability of these specimens is also higher 
than iron for magnetising forces below saturation, whilst the max. induction 
* These two specimens contain 0°18 per cent. of manganese. 
| This specimen also contained 0°5 per cent. of aluminium and high carbon: it is therefore a silicon 
aluminium steel. 
