ATOMIC WEIGHTS 53 i 



YTTERBIUM A^'D LUTECIUM. 



Altliough ytterbium was long sii]ip()sed to be a definite element, it has 

 recently been shown to be complex, and its oxide is a mixture of at least 

 two distinct earths. Xevertheless, the data relative to the atomic weight 

 of the old ytterbium are worth assembling, if only for historical reference. 



The first good series of determinations was by jSTilson,' who effected 

 the synthesis of the sulphate from the oxide in the usual manner. His 

 figures are as follows : 



Mean, 62.147. ± .0036 

 Hence Yb = 173.18. 



Astrid Cleve,'' by the same method, olitained the subjoined results 



Mean, 62.141, ± .0044 

 Hence Yb = lT3.13. 

 Brill,^ who used the microbalance, gives the following figures: 



Yb,{SO,)s. 



106.00 



92.35 



Mean, 62.108, ± .0407 



Hence Yb = 172.85. 



Brauner,* from 1.67279 grammes Yb.O,, obtained 2.69209 of 

 Yb,(S0j3. Percentage YbsO,, 62.137, and Yb = 173.10. There is 

 also a preliminary note by G. and E. Urbain.'' who found Yb = 172.6. 

 but who give no details of the determination. 



1 Compt. Rend., 91, 56. 1880. Ber. Deutsch. cheni. Ges., IS. 1430. 

 ^Zeitsch. anorg. Chem., 32, 129. 1902. 

 ' Zeitsch. anoi-ff. Cheiii., 47, 464. 1905. 

 ^ Abegg's Handbudi, 3 (1), 33.J. 

 = Compt. Rend., 132, 130. 



