276 Dr. Fleming, and Messrs. Ashton and Tomlinson on 



has a value of 1*97, considerably above the value obtained for 

 the cast cobalt. It appears, therefore, as if the hysteretic 

 exponent for cast iron at moderate and high inductions re- 

 sembles that of wrought iron, and that of nickel and cobalt at 

 very low induction densities. The permeability curves for 

 this cast iron in terms of B and H as abscissas are shown in 



The chemical composition of the cast-iron ring we em- 

 ployed was kindly determined for us by Mr. R. A. Hadfield. 

 His analysis showed the presence of 2 per cent, of silicon, 

 2'85 of carbon, and 0'5 of manganese. It was therefore not 

 in any way abnormal. The following tables give an epitome 

 of the observations on these cast cobalt and cast-iron rings. 



Observations on the Magnetic Hysteresis of Cast Cobalt. 

 Cyclical Magnetization Curves. 



Loop I. 



Loop II. 



Loop III. 



Loop IV. 



H. 



B. 



H. 



B. 



II. B. 



H. 



B. 

 4110 



6-67 



911 



13-23 



2341 



17-91 



3106 



25-76 



492 



805 



713 



1928 



917 



2549 



1499 



3196 



324 



676 



3-75 



1595 



4-18 



2018 



728 



2809 



2-28 



586 







1092 







1436 







1807 



0-99 



453 



- 3-21 



418 



- 3-42 



727 



- 5-28 



420 







347 



— 5-36 



- 286 



- 5-92 



- 205 



- 8-91 



-1005 



-099 



222 



- 713 



- 895 



- 8-97 



-1288 



-12-46 



-2023 



-2-28 



24 



' - 9-34 



-1536 



-12-89 



-2312 



-18-87 



-3281 



-325 



-164 



-11-72 



-2069 



-1791 



-3106 



-25-76 



-4110 



-4-92 



-537 



-13-23 



-2341 











-667 



-911 



1 













Loo 



P V. 



Loo 



3 VI. 



Loop VII. 



Loop VIII. 



H. 



B. 



H. 



B. 



H. 

 48-54 



B. 



5869 



H. 

 6108 



B. 



30-53 



4569 



38-56 



5216 



6519 



17 64 



3886 



21-15 



4397 



26-79 



4980 



36-38 



5705 



7-75 



3047 



10-19 



3536 



1091 



3751 



16-39 



4440 







2022 







2177 







2299 



o • 



2418 



- 5-23 



494 



- 6-23 



201 



- 5 60 



674 



- 611 



550 



- 9-51 



-1182 



-10-19 



-1350 



-10-91 



-1376 



-11-02 



-1337 



-14-41 



-2490 



-1684 



-2912 



- 1703 



-2846 



-19-51 



-3220 



- 20-85 



-3535 



-26-83 



-4257 



-28-20 



-4383 



-36-99 



-5123 



-3053 



-4569 



-38 56 



-5216 



-4854 



-5869 



-6108 



-6519 



