PEIRCE. — MAGNETIZATION OF IRON. 145 



B and H in jfields ^ of commercial strength. It is clear from the 

 curve in Figure 8 the ordinates.of which are H/I = 1/k, that the ratio 

 of the abscissa of any point of the curve to its ordinate always yields a 

 value of / somewhat less than the saturation value, whereas the 

 slope against the ordinate axis of the tangent of the curve, after H 





Figure 14. This Figure is plotted form the obsorva t luus made in the Jeffer- 

 son Laboratory upon a piece of "American Ingot Iron" magnetized in the 

 solenoid. The piece was 100 cms. long and 1.279 cms. in diameter. 



equals perhaps 200, is always greater than I. Such curves as this 

 are especially useful when one wishes to study the saturation values 

 of the magnetization in iron or steel. 



Figures 9 and 10 show the results of plotting the reciprocals of the 

 susceptibilities obtained by DuBois, and Roessler in their experi- 

 ments already described. 



5 Lenz and Jacobi, Fogg. Ann. 47, 1839; Mueller, Fogg. Ann. 79, 1850; 

 Von Waltenhofen, Wiener Berichte, 52, 1865; Lamont, Handbuch d. Magne- 

 tismus, p. 41; Sohncke, Elektrotechnische Zeitschrift, 1883; Ruths, Ueber d. 

 Magnetismus weicher Eisenxylinder, 1876; Froelich, Elektrotechnische 

 Zeitschrift, 1881, 1882, 1894; Kennelly, Trans. Am. Inst. El. Eng. 8; Stein- 

 metz, Elektrotechnische Zeitschrift, 13, 1892; Muellendorf, Elektrotechnische 

 Zeitschrift, 22, 1901; 23, 1902; Ivapp, Electrician, 18, 1886; Winkehnann's 

 Handbuch der Fhysik, V, p. 200; Walter, Drude Ann. 14, 1904; Czermak 

 and Hausmaninger, Wiener Berichte, 98, 1889; Du Bois, Wied. Ann. 51, 1894; 

 Fromme, Wied. Ann. 13, 1881; 33, 1888. 



