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 imjDroves, magnetically, a low nickel steel. As the carbon is low in all 

 these specimens (except 803), tliey may more properly be called silicon-iron alloys 

 than silicon steels. 



Tablk XVI. — Silicon-Iron Alloys. 



Table XVI. — Silicon-Iron Alloys {continued). 



The interesting fact is revealed by the above Table that the addition of 2 to 

 5i 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. 



f This specimen also contained 0-5 per cent, of alumiaiura and high carbon: it is therefore a silicon 

 aluminium steel. 



