xvin THE CLASSIFICATION OF THE ELEMENTS 491 



shown in heavy type. It should be noticed that CUiy) and 

 K(i9), both determined experimentally, leave a gap for 

 Ar(i8), although argon has a greater atomic weight than 

 potassium ; corresponding data for tellurium and iodine are 

 not given. In the case of the rare earths, all the numbers 

 from 57 to 72 were observed, either with pure prepara- 

 tions or with mixed fractions, with the exception of 61 

 and 72, which appear to be entirely wanting in these 

 materials. 



TABLE F. ATOMIC NUMBERS AND ATOMIC WEIGHTS. 



I i Hydrogen 



H 1-008 



1 Or Glucinum Gl. 



2 Or Columbium Cb. 



