68 ATOMIC WEIGHT DETERMINATIONS. 



Graham's chemistry. {Gmelin's Handbuch, 5th ed., 1, 46.) 

 Choubiue, from analysis of the chloride and of the sulphate, 

 arrived at 108. 46. {Erdmann's Journ. fur Prak. Chem., S6, 

 1842, 443.) Rammelsberg determined it from the sulphate, 

 which was rose-colored, at 133.17. {Poggend. Ann., 55, 1842, 

 65.) R. Hermann found La = i^ from rose-colored sul- 

 phate. {Erdmann's Journ. fiir Prak. Chem., 30, 1843, 198.) 



C. G. MosANDER : 139£ (0 = 16) ; 870 (O = 100). 



Mosander says that his experiments show the true value 

 to be in the neighborhood of 680, (the metal being assumed 

 bivalent,) but that his salts were not pure, and the determi- 

 nation of little value. {Poggend. Ann., 60, 1843, 301.) 



C. Marignac: U1.12 (0 = 16); 882 (O = 100). 



Eleven experiments were made on the decomposition of 

 the sulphate by barium chloride. The results vary greatly. 

 Marignac wrote later {Annal. de Chim et de Phys., (3,) 38, 

 1853, 148) that experiment had convinced him of the incor- 

 rectness of this determination, and that the true value is 

 about 575. (La bivalent.) {Liebig's Ann., 71, 1849, 306.) 



M. HoLZMANN : 139.S2 (0 = 16) ; 870.15 (0 = 100). 



In three experiments La sulphate was decomposed by 

 ammonium oxalate. In the filtrate from the precipitated 

 oxalate the sulphuric acid was determined as barium salt. 

 The oxalate was decomposed by heat, and the lanthanium 

 oxide weighed. These experiments gave a mean of 580 ; 

 extreme difterence, 5.6; for bivalent lanthanium. In three 

 experiments the iodate was decomposed by oxalic acid, the 

 oxide determined as before, and the iodine titrated by Bun- 

 sen's method. Those experiments gave a mean of 580.2; 

 extreme difference, 5.3. S = 200 ; Ba = 855. In the prepa- 

 ration of the salts analyzed the cerium was separated by 

 peroxidation with magnesium oxide and precipitation as 

 basic sulphate. After the removal of yttrium by potassic sul- 

 phate, the lanthanium and didymium salts were separated, 

 by making a saturated solution of the sulphates at a temper- 

 ature of three or four degrees, and gradually raising the 

 temperature. Lanthanium salt then crystallizes out nearly 

 pure. The purification was repeated until the salts were 

 not discolored when heated in an open crucible over the 

 glass-blower's lamp. Bunsen assisted at this investigation. 

 {Erdmann's Journ. fiir Prak. Chem., 75, 1858, 343.) 



