New Theory of Magnetism. 339 
The variations thus arising are comparatively moderate in 
iron, considerable in hard steel, and enormous in soft steel. 
In one or two cases the equations do not represent the values 
quite so well; in G two sets of constants are given. 
The dimensions of the rings and details of the experiments 
are given in my paper of February last. 
Steel ring J was examined first soft, then hard. then soft 
again, then hard again. Its saturation-point is taken to be 
20,000 throughout. It was wound with about 4000 turns in 
the hard states. 
P.S.—From the above conclusions we can deduce the out- 
line of a chemical theory of the hardening and tempering of 
steel. 
In hard steel the additional constraint, as compared with 
iron, is wholly intra-molecular, 7. e. due to chemical combi- 
nation with a steeling element. This combination must exist 
naturally at a red heat, and be stereotyped by sudden cooling. 
in soft steel the intra-molecular constraint is much dimi- 
nished, and the extra-molecular constraint increased. Hence 
in slow cooling dissociation of the steeling element takes 
place. This requires time. At any point in the slow cooling 
the condition of partial dissociation can be stereotyped by 
completing the cooling suddenly. This constitutes tempering. 
Scheme of the Constants of the Rings. 
J. Steel—BE, F, G, H, K. Soft Iron(Crown). I. Lowmoor. 
Rowland’s J., “ Burden’s Best.” 
kK Ap xC Maximum 
Ring. A. log -. log f. m observed 
. log C=6'1000. | value of p. 
J. First soft state...) 11: 4°78936 | 17595 225 461 
,, second soft state) 129 | 2°82178]| °16552 245 423 
,, First hard state... -01735) 2°16327 | -18925 150 157 
», second hard state] °0236 | 246312] °15340 102 145 
ie ees A cs sds ese °3856 | 2:32208 | °16153 2312 2234 
Ge See a 189 | 201524) -16151 pl 1895 
313) 2°23407 | °15778 57 
2 eae { Se ake call dene aes 2501 
Tet. Ss eee 25 2-24075 | -15325 1808 SF 
i LSS eres ees) 2°30682 | 15973 2422 2070 
lo Loca eee 217 ~+| 2:06175| 16046 2370 2173 
| Rowland’s Table I. 348 =| 2°14941| -16079 2666 2472 
| 
2A 2 
