924 



Mr. R. Rossi on a Relation between the 



words, for every group of elements the root of the series can 

 be expressed by 



B 



v =Av 



v being the atomic volume, A and B constants. 



Thallium falls out of this rule altogether, and in the following 

 calculations was neglected. Table I. gives the values of 



— ^—. .- - — to show the deviations from the above law. 



log v 



Table I. 



Li -166 

 Na -179 



Ou 1 

 1-049 



AgJ 



Mg -277 

 Ca -274 



In J 



•220 



Zn -157 

 Cd -156 







S 



•516 

 •5 IS 



K -176 





Sr -275 



Tl 





Hg -157 



Se 



•517 



Eb -178 

















Cs -181 

















v is the mean of the roots of the two branch series, and was 

 taken from Kayser's Handbucli der Spectroscopie ; the atomic 

 volumes were taken from Meyer's ' Theoretical Chemistry.' 

 The deviations are rather large for Li and Na, but otherwise 

 fall within the limits of -the possible error made in the deter- 

 mination of the factors necessary for the calculation of the 

 atomic volumes (atomic weight and specific gravity). 



The following (Table II.) are the values of the constants 

 A and B for the different families of elements. 









Table II. 









A... 

 B... 



Li, Na, K, 

 Eb, Cs. 



Cu, Ag. 



Mg, Ca, Sr. 



Zn, Cd, Hg. 



AI, In. 



O, S, Se. 



43150 

 •177 



34910 

 •049 



82600 

 •275 



60810 

 •157 



81100 

 •220 



83560 

 •517 



For the trunk series of the alkali metals, the deviations 

 from the above law are even larger than for the branch series, 

 and it is therefore doubtful whether such relation should hold 

 for the trunk series also. It may, however, be remembered 

 that, through the Bydberg-Schuster law, the common root 

 v of the two branch series which we have so far been con- 

 sidering abo represents the range of frequencies of the 



