Property of the Elements, 



321 



and from the above values for the metals and halogens, are 

 compared. 





Li. 



Na. 



K. 



Kb 



F {2- 



•19 



•25 



•34 





•19 



•27 



•34 





4-r 



•32 

 •31 



•36 



•38 



•44 

 •46 



•60 

 •61 



4:1 



... 



•49 

 •50 



'56 



•57 



•69 



•72 



i { ex p- 



. .. 



•62 



•69 



•81 



1 cal. 





•61 



•69 



•84 



It is worthy of notice that the relation holds from the light 

 molecule LiF to the heavy one Rbl. To the same type of 

 compound belong the haloid compounds of Ag and the thal- 

 lious compounds as well as the mercurous and cuprous, if we 

 treat the latter sets as on the type CuCl, HgCl, and so on. 

 Thus we get for the periodic time of Cu in the cuprous state 

 *24, and of Ag *32, numbers which are nearly in the same ratio 

 to one another as the *21 and *30 before, but standing now 

 no longer in the same relation to those of the main family. 

 For Hg in the mercurous state we get a value '55, and for 

 Tl *52. Subjoined is a comparison as before: — 



CI | 



I 



{ 





Cu. 



Ag. 



Hg. 



Tl. 



exp. 



•53 



•57 



... 



•77 



cal. 



•47 



•54 



•78 



•75 



exp. 



•58 



•67 



•85 





cal. 



•59 



•67 



•90 





exp. 



•68 



•76 



1-04 



•94 



cal. 



•70 



•78 



1-01 



•98 



The agreement here is not so good ; in fact these numbers 

 by themselves would prove nothing, but in conjunction with 

 what has gone before they show that we have got approxi- 

 mately the periods which these four metals carry into their 

 compounds. 



Coming to compounds of the type CaCl 2 , we must re- 

 member that MC is 1*5 times its value in the previous class 

 of compounds, so that to get comparable values of p we must 

 takep = (M/d)*M*/ \^VyF. 



Again p is found to be for each molecule the sum of parts 

 due to each atom, and we find the following values for these : 



Mg. Oa. Sr. Ba. 



-10 -15 -20 -25 



numbers which run as 2, 3, 4, 5. Be, the first member of 



