386 M. C. Lea — Atomic Weights of the Elements. 



Art. XLV. — On numerical Relations existing between the 

 Atomic Weights of the Elements ; by M. Caeey Lea. 



In the first part of a paper on the ions it was shown that 

 the elements were divisible into three great classes : those 

 whose ions were always colorless, those whose ions were always 

 colored, and a smaller class whose ions were colored at some 

 valencies and colorless at others.* 



It was also shown that the first class, those whose ions were 

 always colorless, could be arranged in vertical lines so that the 

 horizontal lines contained each a natural group. Also that the 

 elements having both colored and colorless ions were much 

 more closely allied to these than to the group having always 

 colored ions. This last named class does not divide into groups 

 at all, but forms series with the atomic weights immediately 

 following one another. 



Therefore as long as an element has any colorless ions it 

 really seems to belong to the class with the ions all colorless. 

 So much so that when the first class is tabulated the members 

 of this transitional class find vacant spaces into which they 

 naturally fall. To make this clear and to elucidate what fol- 

 lows, I here reproduce Table II from the first part in a con- 

 densed form. (Transitionals in italics.) 



I. 



i H 1 



(Li 7 



F 19 



CI 



35-5 



Br 



80 



J 127 



Na 23 



K 



39* 



Rb 



85 



Cs 132 



II. 







* _ 



Ca 



40 



Sr 



88 



Ba 137 



III. 







Sc 



44 



Y 



90 



La 139 



IY. 











Ti 



48 











V. 











V 



51 



Nb 



u 



Ta 183 



VI. 







_ 







3fo 



96 



W 184- 



I. 











Gu 



63 



Ag 



108 



Au 196 



II. 



Be 9 



Mg 24 



Zn 



65 



Cd 



112 



Hg200 



III. 



B 11 



Al 27 



Ga 



69 



In 



114 



Tl 204 



IV. 



C 12 



Si 28 



Ge 



72 



Sn 



118 



Pb 206 



V. 



N 14 



P 31 



As 



75 



Sb 



120 



Bi 208 



VI. 



16 



S 32 



Se 



79 



Te 



125 



. _ . . 



Th 234 



In the case of some few elements it has not been easy to 

 find published data sufficient to determine with absolute cer- 

 tainty the color of the ions. Further study of this subject has 

 led me to make a slight change in reprinting the above table. 

 I had previously classed the metal cerium as transitional. The 

 eerie ion is undoubtedly colored, but as to the cerous ion there 

 is some uncertainty. Its compounds are nearly colorless, but as 

 they exhibit a slight red tinge the ions may perhaps be colored. 

 It, therefore, seems better in this uncertainty to place cerium 



* This Journal, May, 1895 ; the second part will appear next month. 



