Van tier WaaW Equation of State to Magnetism. Ill 

 Also for cobalt 



a' = 21 from the critical temperature, 

 a' = 20 from the temperature coefficient, 



when m = 0'92 and « t = 0'00031*. 



A table of the estimated values of some of the principal 

 constants for the ferromagnetic elements is given at the 

 end of this paper. 



5. The equations in the last paragraph show that corre- 

 sponding states ought to hold in the relations of magnetic 

 intensity to temperature. 



For any ferromagnetic substance 



c ~ R' 27' 



R' .1 



'~a'I m(l— 2ro)' 

 nd by multiplication we get 



8 1 



«<T C 



27 m(l-2i 



a relation in which a f , I , and R' do not appear. Thus if m t 

 the ratio of the given intensity of magnetization to the 

 maximum, is the same for any ferromagnetic metal the pro- 

 duct a t T e is the same. In other words, in corresponding 

 states the temperature coefficients of the ferromagnetic 

 elements are inversely proportional to their absolute critical 

 temperatures. This deduction has been confirmed by ex- 

 periments published in this Mngazinef. 



The fact that the product a t T c is the same for the same 



m= y f° r a ^ ferromagnetics does not amount to a proof of 



the correctness of the ferromagnetic equation ; it would, 

 however, be of more importance in this respect if it could be 

 shown that octT is numerically equal to 



27 m(l-2m)' 



or that . „, 8 



m(l-2m)x}\ c =-. 



* Ashwovtli, he. eit. 

 t Ibid. 



