252 MAJOR A. E. OXLEY ON THE INFLUENCE OF MOLECULAR 
isotropic mass as viewed in bulk) whereas in a crystalline medium the mass will 
be seolotropic. 
In Part III. evidence was brought forward showing that in the case of 
diamagnetic media the local intensity of magnetization I is of the order 100, while the 
local molecular field between the molecules is of the order 10^ gauss. The energ}^ 
of the molecular configuration of the crystalline medium (over and above that due to 
the molecular configuration in the liquid state) or of the gel at low temperatures, will 
therefore be of the order . H,.. I = 10^ ergs per unit Volume* and the internal stress 
10® dynes per square centimetre, or 1000 atmospheres approximately. For wrought 
iron the energy per unit volume will be 
I^.H^.I = |^x6'5xl0*’xl700 = 5'5x10® ergs 
and the internal stress about 5500 atmospheres. 
In nickel the intrinsic pressure is l'4xl0® dynes per square centimetre or 1400 
atmospheres; in cobalt 4‘4x 10® dynes per square centimetre or 4400 atmospheres, in 
cast iron 4x10® dynes per square centimetre or 4000 atmospheres. These internal 
stresses are a measure of the forces binding the molecules together and should give 
an estimate of the ultimate tensile strength or tenacity of the medium. Moreover 
the tenacities of ferro-magnetic, paramagnetic and diamagnetic media should be 
roughly of the same order. That this is so is seen from the following vainest :— 
Material. 
rlron, (wire). 
Iron, wrought. 
Iron, cast. 
Ferro-magneticNickel (wire). 
Mild steel (0'2 per cent, carbon) 
High carbon steel. 
^Nickel steel (5 per cent.) . . . 
Tenacity 
(dynes per square centimetre). 
5-0-6-Ox 10® 
2-9-4-5x10® 
1-2-1-9x10® 
5- 3x10® 
4-3-4-9x10® 
7-0-77x10® 
6- 2x10® 
This, as we have seen in Part III., p. 93, is compatible with the values of the latent heat of fusion of 
diamagnetic crystalline media. See also infra, pp. 253-4, p. 256. 
t Kaye and Laby, ‘ Physical and Chemical Constants,’ 1918, p. 28. 
