362 THE ATOMIC WEIGHTS. 



It is not worth while to combine this result with the earlier determi- 

 nations, for they are now worthless. 



YTTERBIUM. 



For ytterbium we have one very good set of determinations by Nilson.* 

 The oxide was converted into the sulphate after the usual manner : 



1.0063 g rm - 



1.0139 " 



.8509 " 



.7371 " 



1.0005 " 



.8090 " 



1.0059 " 



Percent. Y&. 2 O 3 . 



.6186 giro. 62.171 



.6314 " 62.149 



.3690 " 62.155 



.1861 " 62.145 



.6099 " 62.147 



.3022 " 62.126 



.6189 <( 62.134 



Mean, 62.147, .0036 



Hence, with S0 3 = 79.465, Yb = 171.880. 

 If O = 16, Yb = 173.190. 



TERBIUM, THULIUM, HOLMIUM, DYSPROSIUM, ETC. 



For these elements the data are both scanty and vague. Concerning 

 the atomic weights of holmium and dysprosium, practically nothing has 

 been determined. To thulium, Clevef assigns a value of Tm = 170.7, 

 approximately, but with no details as to weighings. Probably the value 

 was computed with S0 3 = 80. 



For terbium, ignoring older determinations, Lecoq de Boisbaudran has 

 published two separate estimates.]! First, for two preparations, one with 

 a lighter and one with a darker earth, he gives Tb = 161.4 and 163.1 

 respectively. In his second paper he gives Tb = 159.01 to 159.95. These 

 values probably are all referred to S0 3 = 80. 



*Compt. Rend., 91, 56. 1880. Berichte, 13, 1430. 



t Compt. Rend., 91, 329. 1880. 



J Compt. Rend., 102, 396, and in, 474. 



