the Intrinsic Field of a Magnet. 409 



The conclusion from these experiments is that the specific 

 heat o£ neither nickel nor iron shows any change in the 

 critical temperature greater than 2° C. or 3° C, whereas 

 with the alternating fields employed the critical temperature 

 for magnetism must have been lowered very considerably 

 more than this. Hence the loss of the intrinsic magnetic 

 field at this lower magnetic critical temperature is without 

 commensurate effect on the temperature at which the sharp 

 change of the specific heat takes place. 



Thus the magnetic properties may be changed in these 

 ferro- magnetic metals without any change of corresponding 

 magnitude taking place in the electrical or thermal properties 

 here considered, and the evidence for an enormous intrinsic 

 magnetic field i s no t forthcoming. 



o 



5. Corresponding States. — It has already been remarked 

 that the critical temperature probably signifies a physical 

 change akin to a change of state, and this view suggests that 

 the various properties of the metals which have a critical 

 temperature may behave correspondingly at corresponding- 

 temperatures. The observations now obtained on the varia- 

 tion of electrical resistance with temperature together with 

 those of other investigators, and the experiments on the 

 change of thermo-electric power with temperature which 

 have been described above, allow the question to be tested. 



(a) Electrical Resistance. 



Observations of my own on nickel and some on iron by 

 D. K. Morris * agree very closely with a set of experiments 

 on nickel and iron carried out carefully by Honda and 

 Oguraf, and the following table (Table II.) is constructed 

 from their observations on the variation of resistance with 

 temperature. 



The absolute temperature of the critical point and the 

 resistance at that point are taken as unity, and other values 

 are treated as fractions of the unit. The graphs in fig. 3 

 enable the curves of reduced temperature and reduced re- 

 sistance of nickel and iron to be compared. Up to the 

 critical point (unity on each scale) they follow paths which, 

 although not identical, are similar in form, the maximum 

 difference from exact correspondence being 7 per cent. 



* Morris, Phil. Mag. vol. xliv. p. 213 (1897) ; Phys. Soc. Proc. vol. xv. 

 p. 134. 

 t Houda & Ogura, Math. Phys. Soc. Proc. vol. vii. p. 231 (1914). 



