LANTHANIUM. 69 



C. CzuDNOWicz : U0.3 (O = 16) ; 876 (O = 100). 

 Czudnowicz especially disclaims making this as an atomic 

 weight determination and he adopts Holzmann's value. 

 The salt analysed was the sulphate, and the method the 

 same as that employed by Holzmann. [Erdmann's Journ. 

 fur Prak. Chem., 80, 1860, 31.) 



R Hermann : 139.32 (0 = 16) ; 870.75 (0 = 100). 



Hermann analyzed the carbonate by decomposing it over 

 mercury by sulphuric acid, and measuring the carbon di- 

 oxide liberated. The residue was heated to redness and 

 weighed. This experiment gave La = 580.4, the metal 

 being assumed as bivalent. The carbonate was prepared 

 by precipitating the sulphate with sodium bicarbonate. In 

 three experiments the sulphate was decomposed by ammo- 

 nium oxalate and the oxide, obtained by incinerating the 

 oxalate, weighed. These analyses gave La = 580.7. In 

 one experiment the chloride was analysed with argentic 

 nitrate, giving La = 580.4. The number taken is the mean ; 

 extreme difference 2.3. In the preparation of the salts, 

 cerium was separated as basic sulphate. La and didymium 

 were partially separated by crystallization after which a por- 

 tion of the nearly pure sulphate was precipitated by ammo- 

 nia, and this precipitate digested with the mother liquor. 

 Didymium sulphate is by this means completely precipitated. 

 S = 200; 01=443.2; = 75. Hermann remarks that 

 his former determination was made with impure material. 

 {Erdmann's Journ. fiir Prak. Chem., 82, 1861, 395.) 



H. ZscHiESCHE : 135.27 (0 = 16). 



Determined by six experiments on the sulphate. The 

 water was driven off at 230°, and the anhydrous salt ex- 

 posed to a white heat until the weight became constant, and 

 on being tested, showed no sulphur. The mean result was 

 La = 45.09; extreme difference, 1.15. In preparing the 

 salt from cerite, the cerium was peroxidized with red lead 

 and nitric acid and was precipitated as basic nitrate. The 

 didymium was separated by partial precipitation with 

 oxalic acid and concentration, these operations being re- 

 peated as long as the absorption lines of Di were percepti- 

 ble in the spectroscope. A correction was made for the 

 loss of weight of the crucible, and there was no dust upon 

 its sides. S = 16. [Erdmann's Journ. fur Prak. Chem., 

 lOJf., 1868, 174; 107, 1869, 72.) 



