ERBIUM. 53 



P. T. Cleve : 147.01 (O = 16). 



Determined by the conversion of didymium oxide into sul- 

 phate. The number is the mean of six experiments ; ex- 

 treme difterence 0.58. The Di was separated from lantha- 

 nium by repeated precipitations of basic nitrate from nitric 

 acid solution, conversion into formate and decomposition of 

 this salt by heat. {Kopp's Jahresbericht, 1874, 259. Bulle- 

 tin Soc. Chimique, (2,) SI, 246.) 



W. F. HiLLEBRAND : 144.78 (0 = 16). 



Determined by one experiment on the conversion of 

 metallic Di into nitrate, and then, by heat, into oxide. The 

 impurities were determined. The metal was reduced elec- 

 trolytically from the chloride. {Poggend. Annul., 168, 1876, 

 78.) 



ERBIUM. 



The physical and chemical analogies of the salts of this 

 element have led MendelejefF {Liebig'sAnnaL, Suppl. 8, 1871, 

 195,) and P. T. Cleve {Kopfs Jahresbericht, 1874, 260; Bul- 

 letin Soc. Chimique, (2,) 21, 344,) to regard it as triatomic, 

 and its atomic weight as about 170. 



'&' 



M. Delafontaine : 113.04. (O = 16). 



M. Delafontaine investigated gadolinite by Mosander's 

 method, and obtained besides yttrium, two substances which 

 he regarded as erbium and terbium. From the sulphates, 

 in which he supposed the metals to exist as protoxides, he 

 determined erbium at 496 and terbium at 471 for O = 100. 

 Popp (Liebig's Annalen, 131, 189,) and Bunsen and Bahr 

 {Ibid, 137, 1,) have shown that Mosander's method gives 

 only mixtures. Delafontaine's terbium is thought to have 

 been chiefly the erbium of other chemists. {Biebig's Annul., 

 134, 1865, 108.) 



Bahr and Bunsen : 168.9 (O = 16). 



A known weight of erbium oxide was treated with a very 

 slightly excessive quantity of sulphuric acid; the solution 

 evaporated and the excess of acid driven off at as low a 

 temperature as possible. The increase of weight indicates 

 112.6 for S = 32. The oxide was prepared from gadoli- 



