EXPERIMENTAL RESEARCHES ON DRAWN STEEL. 
23 
immediately after magnetisation and before heating and cooling being about 700. They 
were then remagnetised, boiled for some hours, heated and cooled many times, and 
the coefficient determined ; after this they were laid aside for several months. This 
was in November, 1898. When re-examined in June and November of 1899, and 
again in March, 1900, very little change had taken place in either the coefficients or 
the intensities, which were about — 0'000025 and 700 respectively. Both magnets 
were almost exactly the same in their behaviour in every respect, as will be seen from 
Table VIII., which gives their history. 
Table VIII.—Influence of Time on the Temperature Coefficient and Pvesidual 
Magnetic Intensity of Drawn Steel when Tempered. 
H 30 Piano Wire, 12 centims. long, heated to redness and quenched. 
Residual intensity. 
Temperature 
Date. 
coefficient. 
Remarks. 
Initially. 
Finally. 
a. 
X lO-i 
1898. 
Magnetised first time and heated 
and cooled 12 times. 
October 14. . . . 
707 
682 
— 
„ 24. . . . 
686 
675 
-0-44 
Remagnetised, boiled for 2| hours. 
and heated and cooled 12 times. 
November 9 . . . 
740 
716 
-0-32 
1899. 
June 16 .... 
736 
730 
-0-26 
November 8 . . . 
718 
711 
-0-24 
1900. 
March 29 ... . 
704 
700 
- 0 • 25 
Second Sample. 
II 30 Piano Wire, 12 centims. long, heated to 
redness and quenched. 
1898. 
Magnetised first time and heated 
and cooled 12 times. 
October 14 ... 
700 
680 
— 
November 3 . . . 
677 
669 
-0-45 
Remagnetised, boiled 2^ hours, 
heated and cooled 12 times. 
„ 9 . . . 
742 
728 
-0-27 
1899. 
June 16. 
749 
742 
-0-32 
November 8 . . . 
726 
721 
-0-21 
„ 15 . . . 
— 
— 
— 
Boiled 3 hours. 
„ 15 . . . 
724 
720 
-0-25 
1900. 
April 9. 
709 
709 
-0-24 
