322 A New Periodic Property of the Elements, 



the family, is absent through want of experimental data. 

 For the halogen atoms as F 2 , Cl 2 , Br 3 , and I 2 , the following 

 are the values : — *156, *312, *468, and '624 ; again, the series 

 1, 2, 3, 4, although the value *156 of the constant of the family 

 is not double the previous value *116 for the single atoms. 

 But it must be remembered that we are using the empirical 

 relation aTMr= constant without knowing whether the value 

 of the constant may not change with change of type of com- 

 pound. This does not affect the present purpose, which is to 

 show the existence of harmonic relations. 



To prove the substantial correctness for the values given 

 for the Be family, and the double halogen atoms, the following 

 comparison is furnished : — 







Mg. 



Ca. 



Sr. 



Ba. 



H e J: 



•28 



•30 





•44 



•26 



•31 





•41 



<*•& 



•42 



•46 



•50 



•53 



•41 



•46 



•51 



•56 



Mel 





•61 



•62 



•68 

 •67 



•68 

 •72 



MS 







•87 



•84 





... 



•82 



•87 



As the comparison ranges from the light molecule MgF 2 to 

 the heavy one Bal 2 , it proves the main principle under dis- 

 cussion, in spite of some noticeable disagreements in the two 

 series of values. The following are some values for other 

 dyad elements: — 



Cd. 



Hg. 



Cu. 



Pb. 





•27 



•53 



•22 



•39 





giving the following 



comparison : — 









Cd. 



Hg. 



Cu. 



Pb. 



<*{S 



•59 



•82 



•53 



•71 



•58 



•84 



•53 



•70 



Ms 





1-01, 





•82 





1-00 



. . . 



•86 



*&. 



'88 



1-15 





1-04 



•89 



1-15 





1-01 



The only compounds of 



this type which are 



thoroughly 



irregular are those of zinc 



; '66 for ZnCl 



2 , '76 for ZnBr 2 , and 



•85 for Znl 2 , which give a 



smaller value 



for Br 2 -Cl 2 , and for 



I 2 -Br 2 than holds in 



the 



other dyad compounds. 



For com- 



pounds of metals of higher atomicity than the dyads there are 

 not enough data to give useful conclusions ; the haloid com- 

 pounds of As and Sb give irregular results. 



