ox THE MAGNETIC QUALITIES OF IRON. 
997 
King II. 
Limits of H. 
Limits of I. 
Coercive force. 
43-21 
1404 
i 
7-71 I 
32-42 
1328 
7-43 I 
21-89 
1195 
7-06 I 
13-66 
960 
6-48 ' 
10-98 
810 
6-00 i 
8-91 
643 
5-61 
7-48 
490 
5-01 
6-12 
317 
4-28 
4-76 
145 
2-83 
4-08 
94 
1-94 
2-14 
25 
0-45 
Fis?. 9. 
Coercive Force and I. Rings I. and II. 
In fig. 9 the coercive force is plotted in relation to I. From this figure it is 
possible, by extrapolation of the curve, to arrive at a probable estimate of a definite 
physical constant of the material which forms a good criterion of magnetic hardness, 
namely, the coercive force which would correspond to the state of magnetic saturation. 
This, in other words, is the demagnetizing force which would be just sufficient to 
remove magnetism from a piece which had been magnetized to literal saturation. 
We know that the saturation value of I. in wrought iron and steel is about 1700.* 
A. conjectural extension of the curves along the straight lines which they follow in 
the region of strong magnetization shows that the coercive force of saturation is 
probably about 5'5 in the (rather hard) iron of King I., and 8‘5 in the steel of 
King II. 
* ‘ PM Trans,’ 1889, A, p. 221. 
