466 



calculated from (24) with Ur.n = ^T. The two other curves are 

 taken from tig. 1, PI. I, of (Jomm. N". 114 bj Wkiss and Kamer- 

 LTNGH Onnes (Febr. 1910) ^j and represent the results of the obser- 

 vations concerning magnetite and nickel 'J. 



The points indicated by circles have been calculated with the 

 equations (23) to (26). The following values of 0^ were adopted ^) 



for niagu elite ^„ = 75 

 „ nickel 6'„ = 2100. 



The agreement between observation and calculation may be regarded 

 as quite satisfactory for magnetite ^). This indicates that the a])i)lication 

 of the quantum-theory made here, corresponds in its principal features 

 to reality in particular as regards the assumption of a zero-point energy. 



For nickel the agreement is somewhat less satisfactory *). Yet, 1 



" 1) A reading from the curve for magnetite published in Les idees modernes sur 

 la Constitution de la Matière (Conférences Paris 1912) showed but unsignificant 

 differences from the readings from the figure in Comm. N'J. 114. 



2) The values of -^ have been calculated with the values of Sq given in the text. 



'^] Again the large difference in ^o between monatomic elements and compounds 

 calls for attention. This difference corresponds to a similar difference (in the reverse 

 sense) of the moment of inertia (cf. p. 4(50 note 3). It is connected with their 

 high values of 6^ (i. e. with their small' moments of inertia), that the rotational 

 energy at ordinary temperatures makes only a relatively small contribution to 

 the specific heat of monatomic solids. 



*) From the original of Fig. 1 the following data were read for magnetite : 



The agreement might still have been improved for the higher temperatures by 

 choosing another to- T^^is has not been done as presumably in the observational 

 curve the correction for dilatation has not yet been applied. If this correction has 

 still to be applied the agreement between observation and calculation lies, I think, 

 within the degree of accuracy of the measurements. 



5) For nickel the following data were read: 



