Hackli — Modification of the Periodic Table. 483 



minals of the periods. Beginning in any period with a 

 rare gas, whose electro potential we consider to be ± oo 

 we find that the elements following it change from posi- 

 tive to negative until the period ends in a rare gas again. 

 This is shown in Table I. It will be noticed that in this 

 arrangement only the first four and last four members of 

 the periods are recorded and that the elements of the 

 carbon group form the transition line from a positive to 

 a negative element. The elements of the carbon group 

 may be regarded as the zero point in each period respec- 

 tively. We have then in the first and second period one 

 zero point each (C, Si) and in the third and fourth period 

 two zero points each (Ti-Ge, Zr-Sn), while the very long 

 fifth period has three zero points. When we plot the 

 relative position of the elements in the displacement 

 series against the atomic numbers, we obtain the follow- 

 ing interesting curve (p. 484). 



The displacement series was constructed from such data 

 as offered by Wilsmore, 17 Palmaer, 18 Abegg 19 and those 

 given in the Chemiker Kalender 20 and Landolt Born- 

 stein. 21 There are interesting analogies in this curve. 

 The first six and the last seven elements of the four com- 

 plete periods have similar positions ; this makes thirteen 

 elements whose position is determined. It is, therefore, 

 clear that in the fifth period from X to Nt there can be no 

 unknown rare gas with its corresponding thirteen ele- 

 ments ; we must rather assume that, as the potential dif- 

 ference between the first and last member in each group 

 is the same, and divided among 7, 17, 35 elements, the 

 difference in potential among the 35 elements is naturally 

 very small and gives a group of very similar elements, 

 that is the group of the rare earth metals. In other 

 words the potential difference from Li to F, and from 

 Na to CI in the first two periods, is divided among seven 

 elements. The potential difference from K to Br, and 

 from Eb to I in the two long periods, is divided among 

 seventeen elements, which show alreadv the formation of 

 "vertical" groups (Mn-Fe-Co-Ni, etc.). In the fifth 

 period this same potential is divided among 35 elements, 

 thus forming: naturally a very long group of elements in 

 which the difference of their properties is very slight. 



A similar curve is obtained by plotting the maximum 

 polar number of the elements against the atomic number 

 as shown in fig. 2. The negative or positive polar num- 



