34 ATOMIC WEIGHT DETERMINATIONS. 



CERIUM, 



The specific heat of metallic cerium, as determined by 

 W. F. Hillebrand, is 0.04479, and the atomic heat G.18 if the 

 atomic weight is 138. {Poggend. AnnaL, 158, 1876, 86.) 



It is well known that cerium is always accompanied in 

 nature by lanthanium and didymium. The former was dis- 

 covered in 1839, and the latter in 1843, both by Mosander. 



W. HisiNGER : 137.93 (0 = 16). 



According to Hisinger, as reported by Berzelius, the lower 

 oxide of cerium contains 14.821 per 100 Ce, giving the 

 atomic weight at 574.718 for = 100, if the lower oxide is 

 regarded as a protoxide. {Poggend. AnnaL, 8, 1826, 186.) 



T. TnoMSON : 150 (0 = 16). 



Thomson analysed the sulphate and obtained for cerium 

 the value 625, (O = 100.) [He probably took barium = 70.] 

 {System of Chem., 7th ed., 1, 1831, 466.) 



F.J. Otto: 138.91 (0 = 16). 



According to Gmelin, Otto found in an approximate de- 

 termination Ce = 578.8, and recorded it in his revised trans- 

 lation of Graham's Chemistry, 1, 1840, 222. 



A. Beringer : 138.^,8 (O = 16). 



[Three analyses of cerous chloride with silver give the 

 atomic weight of cerium at 576.375, or 92.22, if Ag = 

 107.93, and CI = 35.457. Inconsistent results are given for 

 an analysis of the sulphide.] Three analyses of the sul- 

 phate in which the oxide was determined, gave 57.4717 per 

 cent, so-called protoxide, [or Ce = 576.31, or 92.21, if S = 

 32.0742.] Analysis of the formate gave Ce = 577.04 for 

 C == 75.85. The material for the preparations was eerie 

 oxide obtained from cerite, and purilied from lanthanium 

 by digestion with very dilute nitric acid. The lower oxide 

 was assumed to be Co 0. {Liebig's AnnaL, 4^, 1842, 134.) 



E. Hermann : 138 (O = 16). 



The lower oxide was assumed to be Ce O. 23.523 parts of 

 anhydrous cerous sulphate gave 29.160 parts of barium sul- 

 phate, giving Ce = 575, for O = 100, Ba = 856.88, and 

 S = 201.16. The salt was obtained by precipitating basic 



