15 
EXPEELMENTAL RESEARCHES ON DRAWN STEEL. 
If, however, the magnetic force which has been applied is strong enough to leave 
a residual intensity which, after heatings and coolings, still remains in the reverse 
direction to the original, the positive coefficient is again established. 
13. In the experiments recorded above the intensity was raised a step at a time, 
after each series of heatings and coolings, and a suspicion might be entertained that 
the magnetic state at any stage had been seriously disturbed by the heatings and 
coolings at a preceding stage. The next series of experiments was undertaken to 
test this question, and accordingly, after any series of heatings and coolings, the wire 
was completely demagnetised by reversals before the magnetisation was carried a 
grade higher. Beginning at a low intensity, the magnetisation was thus carried to 
its highest value by easy steps. In returning, the wire was magnetised strongly and 
then a small reversed force applied, enough to remove some of the residual magnetism ; 
after heating and cooling, the wire was demagnetised, carried again to its highest 
intensity, and a larger fraction of the residual magnetism removed, heating and 
cooling repeated, and so on. In this way the following table was constructed 
(Table V.). 
Table V.—Effects of Heating and Cooling on Residual Magnetism with Demagne¬ 
tisation between each Step. Relation of Intensity to Temperature Coefficient. 
H 30 Piano Wire. 
Magnetising 
Induced 
Residual 
intensity. 
Temperature 
Permanent 
Smsceptilhlity, 
K = I/H. 
force, 
H. 
intensity, 
I. 
Initially, 
h. 
Finally, 
h 
coefficient, 
a. 
change. 
8 Ho 
70 
25 
12 
X 10 
+ 3-05 
X 10-2 
- 50-8 
i 
8-2 
12-79 
181 
112 
86 
+ 4-07 
-23-1 
14-1 
15-26 
288 
247 
212 
+ 4-98 
- 13-9 
18-8 
18-18 
500 
476 
432 
+ 5-15 
- 9-4 
27-5 
22-44 
785 
702 
653 
+ 5- 06 
- 7-0 
35 - 0 
41-07 
1141 
915 
839 
+ 4-66 
- 6-5 
27-7 
101-20 
1334 
1028 
961 
+ 3-27 
- 6-5 
13-2 
- 8-53 
— 
810 
813 
+ 4-45 
+ 0-4 
- 13-69 
— 
516 
535 
+ 4-37 
+ 5-8 
_ 
- 15-03 
— 
291 
331 
+ 4-16 
+ 13-8 
- 17-05 
- 17 
+ 39 
-4-10 
— 
The same general features as before again exlnljit themselves, namely, a rise and 
fall of the temperature coefficient as the intensity proceeds either to a maximum or 
proceeds to a minimum, the largest value of a occurring earlier for increasing than 
for decreasing intensities ; a loss, ^ negative, so long as the applied torce has been 
positive and a gain when the force has been negative, the magnitude of the gain 
