THE YTTRIUM GROUP. 243 



y\0.,. yf^{SO,)y Percent. Yt.fi^. 



1.4060 gnn. 2.8925 grm. 48.608 



1.0930 " 2.2515 " 48.545 



1.4540 " 2.9895 " 48.637 



1.3285 " 2.7320 " 48.627 



2.3500 " 4-8330 " 48.624 



2.5780 " 5.3055 " 48.591 



Mean, 48.605, ifc .0096 



This series is unquestionably the best of all. From it, if 

 SO 3 = 80, Yt =: 89.485. 



Combining all these data we have the subjoined general 

 mean for the percentage of YtjOg : 



Popp 51.208, zb.OII 



Delafontaine, ist 49.998, db .081 



2d 48.230, rb .055 



Bahr and Bunsen 49.2695, ± .0233 



Cleve 48.605, dr .0096 



General mean 49.637, ±.0069 



Rejecting Popp 48.705, ± .0087 



From the general mean of all, Yt = 97.616. From the 

 mean after excluding Popp's work, Yt = 89.816, ± .007 ; 

 or, if = 16, Yt -= 90.023. 



YTTERBIUM. 



For ytterbium we have one very good set of determina- 

 tions by Nilson.* The oxide was converted into the sul- 

 phate after the usual manner : 



* Compt. Rend., 91, 56. i! 



