P eirce— Magnetic Properties at High Excitations. 7 



long. When it was purchased this iron was very soft as is 

 shown by the numbers in the second column, which give the 

 values of the induction {JB) corresponding to the values of H 

 in the first column. When, however, the rod had been again 

 subjected by Mr. Thompson to an elaborate annealing process, 

 its permeability had been somewhat increased as appears from 

 the values of B exhibited in the third column. 



Table II.— Nor 



'icay 



Iron Rod (R) 

 Solenoid. 



M 



xgnetized in the 1 



(Length about 300 centimeters, diameter 1267 millimeters.) 



H 





B 





B 







(Before the iron had 

 been annealed.) 



(After the rod had 

 been annealed.) 



5 





12400 





12560 



10 





14800 





14940 



14 





15460 





15540 



20 





15960 





16040 



30 





16400 





16520 



40 





16650 





16920 



50 





16920 





17220 



60 





17180 





17450 



70 





17400 





17630 



80 





17600 





17820 



100 





17940 





18210 



Specimen Q, like specimen P, was cut from a bar of the 

 best Norway iron two inches in diameter, but the two bars 

 came from different dealers. These irons seem to be nearly 

 alike in temper and in composition. 



Table III. — Specimen of Norway Iron (Q) Magnetized in 



Massive Yoke. 



(Free length about 80 millimeters, diameter 12 '67 millimeters.) 



H B I 



300 20530 1610 



400 21110 1648 



600 22020 1704 



700 22300 1719 



800 2-2510 1728 



1000 22800 1735 



1200 23020 1737 



1400 23240 1738 



1650 24240 1738 



2000 23840 1738 



2400 23490 1738 



