538 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 54 



Feit and Przibylla/ by their vohimolric method, obtained the follow- 

 ing figures : 



YbnO^. 0. Atomic weight Yb. 



.6424 .07808 173.459 



.6408 .07783 173.600 



.6403 .07779 173.547 



.6466 .07858 173.485 



Mean, 173.523, ± .0214 



The complexity of the old ytterbium was proved almost simultaneously 

 by Auer von Welsbach and Urbain. Urbain/ by a long series of fraction- 

 ations, obtained from it two end products, one, nco-yttcrhium, with an 

 atomic weight near ITO; the other, lutecium, approximately 174. Wels- 

 bach.^ whose work was published a little later, proposed for his earths 

 the names ahhharaninni and cassiopeium, and gave more explicit figures 

 as to their atomic weisfhts. His data are as follows: 



Mean, 62.116, ± .0011 



Hence Ad = 172.92. 



Hence Cp = 174.24. 



.0017 



It is not necessary to enter here into the general controversy between 

 Welsbach and Urbain relative to priority. In the matter of nomenclature 

 alone, the priority of Urbain is clear.^ 



His name lutecium is therefore accepted, with Lu = 174.34. For the 

 other component of the mixed earths the original name ytterbium would 

 seem to be preferable to neoytterbium, and Yb = 172.92. The round 

 numbers 174 and 173 are perhaps equally probable, for the determinations 

 by Welsbach are certainly not final. 



' Zeitsch. anorg. Chem., 50, 261. 1906. 



= Compt. Rend., 145, 759, 1907; and 146, 406. 1908. 



•■■ .Monatsh. Chem., 29, 192. 1908. 



* For a roc-lamation of pvioritv, see W'-l-biuli, Mori;it>ih. Ch(in., 33, 695. 



