272 



Mr. W. Brown on Steel Magnets. 



Table III. — The magnetic moment per gramme ; the per- 

 centage loss due to four falls from a height of 150 centim.: 

 and the effects of annealing on the different specimens. 



No. of the 

 specimen. 



Glass-hard. 



Annealed one 

 hour at 100° C. 



Annealed other 



two hours at 



100° 0. 



Mag. 

 mom. 



Per 



cent, 

 loss. 



Mag. 

 mom. 



Per 



cent, 

 loss. 



Mag. 

 mom. 



Per 

 cent, 

 loss. 



I 



60-33 



72-16 

 7000 



1-37 



2-85 

 5-25 



62-3 

 7204 



67-5 



2-84 

 3-45 

 4-67 



61-42 

 72-60 

 69-42 



2-84 

 3-92 

 6-13 



II 



Ill 



No. of the 

 specimen. 



Annealed half 



an hour at 



236° 0. 



Annealed another 



half hour at 



236° C. 



Not remagnetized; 

 and left undis- 

 turbed for 9 

 months. 



Mag. 

 mom. 



Per 



cent, 

 loss. 



Mag. 

 mom. 



Per 



cent, 

 loss. 



Mag. 

 mom. 



Per 



cent, 

 loss. 



I 



62-32 

 68-85 

 65-50 



904 

 14-42 

 18-61 



60-00 

 59-80 

 57-10 



15-9 



29-2 

 26-2 



48-9 

 40-7 

 41-5 



1-6 



3-34 



2-44 



11 



Ill 





The above table is quoted to show the effect of annealing on 

 the different specimens ; it also shows the retentive power of 

 each specimen, which appears to vary inversely as the quantity 

 of manganese in the specimen. Thus specimen III., which 

 has nearly three times as much manganese as either of the 

 other two, in the glass-hard condition has diminished in mag- 

 netic moment by 5'25 per cent. ; and specimen II., which has 

 about 20 per cent, more manganese than I., loses 3 per cent, 

 nearly ; whilst the decrease in the magnetic moment of I. is 

 approximately 1*4 per cent. Specimen I., however, as 

 appears from Table I., differs very much from the others in 

 the quantity of silicon it contains, and it alone contains 

 sulphur. By annealing for one hour in oil at 100° C, the 

 magnetic moment of I. has been slightly raised and that of 

 III. lowered, whilst II. remains unaltered, and so on ; a 



