36 ATOMIC WEIGHT DETERMINATIONS. 



oxalic acid was estimated by difference. This gave GO. 02 

 per cent, cerous oxide, calculated for the anhydrous salt, or 

 Ce = 575.65. The salts were prepared from cerite as fol- 

 lows : the mineral was digested with sulphuric acid, the 

 sulphates formed were leached with water and with dilute 

 nitric acid ; this solution was treated with hydrogen sul- 

 phide, chlorhydric acid was added and cerium oxalate was 

 precipitated. The oxalate was heated with magnesia to 

 convert the cerium into the higher oxide, which was dis- 

 solved in concentrated nitric acid. After diluting the solu- 

 tion, chemically pure basic sulphate was precipitated. In 

 the preparation of cerous sulphate and oxalate oxidation 

 was prevented by the action of sulphurous acid. [Liebig's 

 Annal, 105, 1858, 45.) 



C. Kammelsberg : 138.216 (0 = 16). 



One experiment on the organic analysis of cerium oxalate 

 by heating in a current of oxygen behind copper oxide gave 

 Ce = 575^:9, (O = 100,) or 92.144, (O = 16,) cerous oxide 

 being regarded as Ce O. Ramraelsberg does not adopt his 

 own, but Hermann's determination. [Poggend. AiinaL, lOS, 

 1859, 44.) 



C. Wolf : 136.993 (O = 16). 



Determined from experiments on the sulphate, prepared 

 and analyzed as by Bunsen and Jegel. Wolf purified the 

 basic sulphate by solution in nitric acid and reprecipitation 

 in hot water, aided by recrystallizations. He found that 

 the oftener these processes were repeated the smaller was 

 the atomic weight resulting from the analysis. The purifi- 

 cations were repeated until the salt was spectroscopically 

 free from didymiura, and was perfectly white, (that employed 

 by other investigators had been yellowish or buffi) The 

 value taken, 45.664, [or ^ of 136.992,] was the smallest 

 and last value reached. The investigation was made in 

 Bunsen's laboratory. {SilUman's Am. Joimi., (2,) 4-^, 1868, 

 53.) 



C. H. Wing: 137.01 (0 = 16). 



Two experiments were made on the decomposition of 

 hydrous cerium sulphate with oxalic acid, the cerium oxalate 

 being converted into eerie oxide by heat. The amount of 

 cerous oxide in the eerie oxide was calculated according to 

 Wolfs results, giving for the atomic weight of cerium 45.64 

 and 45.69, S being 32. The cerium was six times recon- 



