483 



of tlie freo alkali-resp. earth alkali atoms, and T the cyaiiizing- 



reaction-temperature. ') It is seen from the fourth row of the table 



V 

 that the same order of magnitude is found everywhere for — . 



Considering the widely divergent circumstances the agreement 

 may even be called remarkable, the more so as a perfectly sharply 

 defined reaction temperature cannot be expected on theoretical 

 ground either. 



e. Dislocation potential. 



The ionisation potential determines the energy required to detach 

 an "outer" electron of a metal atom entirely from a normal path. 

 As under c we arrived at the view that in the compound the 

 electron in question is present in an abnormal path, the conclusion 

 is obvious that not V, but a smaller quantity V — V' can give a 

 measure for the critical supply of energy, in which F' is a quantity 

 which determines the difference of energy between the electron in 

 the abnormal path of the compound and the electron in the free 

 metal atom, that is in the normal path. We shall call this quantity 

 briefly dislocation potential, the electron in the abnormal path will 

 be called dislocated electron. 



The separation of the dislocated electron from the metal rest must, 

 in our opinion, require a quantity of energy that is proportional to 



-) The value of the reaction temperature of CaO is taken from a communication 

 by P. ScHLÜPFER (Schweiz. Ghem. 1919, Heft 29 (30), the values of the ionisation- 

 potential are derived from a summary given bij J. Fhanck (Phys. Zeitschr. 22, 

 413 ('21). The values of T taken for Mg and Ca will be discussed elsewhere, 

 among others because reduction- and cyanizing temperature (resp. the temp, of 

 the formation of metal cyanamid) differ considerably for (the compounds oO these 

 elements. 



