4 Barrett, Brown, & Haprrerp—On the Magnetic and Electric 
pure iron in low fields. And so with other metals alloyed with manganese-steel; a 
10 or 11 per cent. manganese-steel is slightly magnetic, but entirely loses its 
magnetic properties when tungsten-steel, in itself magnetic, is alloyed with 
it. Curiously enough, the addition of the non-magnetic metal copper, added to 
an almost non-magnetic nickel-manganese-steel, slightly increases the magnetic 
susceptibility of the composite alloy, and the same seems true of chromium added 
to a high and practically non-magnetic manganese-steel. Both these results are 
probably due to the softening effect of the added metal, for copper alloyed with a 
hard steel softens it considerably. 
In fact the shght differences in magnetic susceptibility observed in Table I. 
are probably entirely due to differences in hardness of the various alloys. Tested 
with a file, the order of hardness coincided with that of magnetic susceptibility, 
the hardest alloys being the least magnetic. Hence it is not surprising to find 
that an iron alloy which is fairly magnetic when annealed, is made nearly or wholly 
non-magnetic when hardened. ‘This is especially noticeable in the 13 per cent. 
manganese-steel marked 1,010, as shown in Table I. The effect of annealing 
shows itself toa less extent in other specimens in Table I., but is more con- 
spicuous in Table Il. below: the magnetic field in this case being only 45. 
TABLE II. 
EFFECT oF ANNEALING. 
Intensity of 
Maker's Mark. | Principal Constituents. Magnetisation in a 
| field of 45. 
1447 A | JG, GGels Why Uwe, : : : ‘ 370 Ann. 
Pa rt) 3 : : 3 : : 16 Un. 
1447 B | Hes 86-4 Nie 12s : : . : : 0 345 Ann. 
af | °§ “5 ; : ; 3 : : 8 Un. 
1450 A Fe, 85:1; Ni, 12°2; Cr, 2:0, : : ; o | 295 Ann. 
| = 
” ” : ” | 16 Un 
1287 K | Fe, 79:0; Ni, 19:6, . ; 6 : . o | 644 Ann. 
f - o waa ee Semin eg Ma tae | 473 Un. 
1430 A* Fe, 86:7; Cr, 8:9; Mn, 3:1, | 1046 Ann 
” | ” ” ” ’ ° . . . | 37 Un. 
1411 He, 77-3 ; Ni, 14:1; Mn; 5:3 5 Al} 2-3; | 65 Ann 
| | ; 
” | ” ” ” ” : . : 100 Un. 
1449 | Fe, 67-1; Ni, 31-4, j i : ‘ : ; 195 Ann. 
” | ”? ” 846 Un 
* This specimen has 1°3 of carbon. 
