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 [X., 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. 
Tastes XVI.—Stlicon-Iron Alloys. 
Mark Percentage. 
| Bi Ni | c 
1397 A* 0°44 | = 0:22 
4 BS 033 | 0:58 0:26 
898 B DH ° = 0:20 
Se Et 5S | = 0:26 
| 803} 2°25 = 0-67 
1103 A 2-0 3°25 0°38 
4 O 3°25 3°50 0:22 
Taste XVI.—Silicon-Iron Alloys (continued). 
Marks. Most tndnetion; Retentivity. oeLOVLIa——a0e Coercive force. 
Iron 17480 7120 1560 | 1-66 
1397 A 15720 10800 640 7:46 
OFI5} 16940 | 12040 920 7:33 
898 E | 16640 4080 1680 0:90 
ra HT 16480 | 3540 1680 0°85 
803 16000 8320 1345 | 3°70 
OBA | 16240 6990 1120 | 2-00 
6 | 15960 ~—sd| 7270 | 1280 | 1:90 
The interesting fact is revealed by the above Table that the addition of 2 to 
5% per cent. of silicon to steel, as in the specimens 898 E and JH, 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. 
