Ill 



In the communication mentioned above tlie system of molecules 



increase of their distance, as rogards tlie molecular field in particular according 

 to ilie supposition mentioned further on in this note. In fig. 1 the points ++ repre- 



7M1 



53^ 



ilO 



i:j- 



1vV 



Cu 



Fig. 1. 



sent the temperature Tc of the CuRiE-point of alloys of nickel .and copper as a 

 function of the mass-composition x of nickel according to W. Guertli.r and G. 

 Tammann, ZS anoig. Gheni. 52 (1907), p. 25 [iiie quantity .7; introduced here is 

 not to be confused with tliat of equation (4)]. The curve represents the results of 

 tlie calculation. In this I started from equation (IG) of Suppl. N". 32a, applied to 

 the nickel molecules : 



iV„i uqia" 



(«) 



The density of the different alloys of' nickel and copper was assumed to be equal, 

 so that the density of the nickel in the alloy may be put equal to o = n x (the 

 index 1 indicates that the quantity concerned corresponds to x = l, that is in our 

 case to nickel'. Fuither the coefficient of the molecular field, Nm, is assumed not 

 to depend on the composition. This assumption involves, that iJie molecular field, 

 the magnetisation per unit of mass being kept constant, is proixjrtional to the first 

 power of the density of the ferromognetic component ; this relationship differs 

 from th(! result obtained by Weiss, G.R. 157 (1913), p. 1405, with alloys of the 

 two ferromagnetic metals nickel and cobalt from the manner in which the con- 

 stant of the molecular field, derived on the assumption of equipartition, depends 

 on the composition. 



Further S^ has been put (cf g 5 of this paper proportional to X'U : 



^0 --- ^0,1 .'■■^/» {h) 



The equation which determines the value of Tc which corresponds to a given 



