226 THE ATOMIC WEIGHTS, 



account. The death of Dr. Wolf interrupted the investiga- 

 tion, the results of which were edited and published by Pro- 

 fessor F. A. Genth. 



The experiments of Wolf seem to have hitherto escaped 

 general notice, except from Wing, who has partially verified 

 them.* This chemist, incidentally to other researches, puri- 

 fied some eerium sulphate after the method of Wolf, and 

 made two similar analyses of it, as follows : 



Sulpha Ic. Water. CeO.^. Per cetit. Ce0.y 



1.2885 C'"- '707 g™''- -6732 grm. 60.225 



1.4090 " •i<^57 " -7372 " 60.263 



Mean, 60.244, ± -012 



The ceroso-ceric oxide in this case was perfectly white. 

 The cerium oxalate which yielded it was precipitated boil- 

 ing by a boiling concentrated solution of oxalic acid. The 

 precipitate stood twenty-four hours before filtering. 



We may now combine the results of Wolf and of Wing, 

 as follows. The two concordant experiments of Wolf's 

 series three and four may be united, giving a mean of 

 60.267, ± .001 : 



Wolf, 1st series 60.494, zh .024 



" 2d " 60.302,^,004 



" 3(1 and 4th series 60.267, =h -ooi 



Wing 60.244, ± -012 



General mean 60.271-, zb -ooi 



This mean, the percentage of CeOx in the anhydrous sul- 

 phate, gives Ce = 137.724 ; or, if = 16, Ce = 138.039. 

 This varies widely from the ordinarily accepted value as 

 determined by Buehrig. 



In 1875 Buehrig'sf paper upon the atomic weight of 

 cerium w^as issued. lie first studied the sulphate, which, 

 after eight crystallizations, still retained traces of free sul- 

 phuric acid. He found furthermore that the salt obstinately 

 retained traces of water, which could not be wholly expelled 

 by heat without partial decomposition of the material. 



* Amer. Journ. Sci. and Arts, (2,) 49, 358. 1870. 

 f Journ. fur Prakt. Chem., 120, 222. 



