54 ATOMIC WEIGHT DETERMINATIONS. 



nite. The mineral was decomposed with chlorhydric acid, 

 and the earths precipitated with oxalic acid. The oxalates 

 were converted into nitrates, the cerium metals separated 

 with potassic sulphate, and calcium and magnesium with 

 ammonia. If the nitrates of yttrium and erbium are dis- 

 solved in boiling water, basic erbium nitrate with some 

 yttrium crystallizes out, leaving yttrium nitrate with some 

 erbium in solution. The process of partial crystallization 

 was continued as long as the atomic weight of the erbium 

 salt continued increasing. Bahr and Bunsen believe, how- 

 ever, that the atomic weight may be some hundredths higher. 

 The salt was spectroscopicall}- free from didymium. [Liebig^s 

 AnnaL, 137, 1866, 2.) 



P. T. Cleve and 0. M. Hoeglund : 170.55 (0 = 16). 



Determined from four syntheses of the sulphate, giving 

 113.7 on the diatomic hypothesis. The oxide was purified 

 bj^ heating the nitrates, etc., according to Berlin. {Blom- 

 strand in ^Berlin, Ber. der Cliem. Ges., 1873, 1467; Bull. Soc. 

 CMmique, 1873, 193 and 289.) 



FLUORINE. 



Dumas and Peligot and others have determined the vapor- 

 density of a number of fluorine compounds. They corres- 

 pond to an atomic weight of about 19. {L. Meyer, I. c.) 



H. Davy : 18.86 (O = 16). 



Determined by the conversion of Derbyshire spar into sul- 

 phate. 100 parts of spar gave a maximum of 175.2 parts 

 calcic sulphate. [If 8 = 32; Ca = 40; the value follows.] 

 {Phil. Ti^ans., IO4., 1814, 64.) 



J. J. Berzelius : 18.85 (0 = 16). 



Determined by conversion of calcic fluoride into sulphate. 

 100 parts fluoride gave, in mean of three experiments, 175 

 parts sulphate ; extreme diflerence, 0.2. [If S = 32 ; Ca 

 = 40; the value follows.] [Poqgevd. AnnaL, 8, 1826, 18, 

 and Lehrhuch, 3, nm.) 



