62 ATOMIC WEIGHT DETERMINATIONS. 



C. Mariqnac : 126.844 (0 = 16). 



In five experiments a known weight of silver was dissolved 

 in nitric acid and precipitated by a known amount of potas- 

 sic iodide according to Pelouze's modification of Gay-Lussac's 

 method. The mean result was 100 Ag = 153.74 KI in air; 

 extreme difference, 0.14. Stas has recalculated this result 

 for Ag = 107.93, and K = 39.137. The atomic weight so 

 found is, in vacuo, 126.847. In three experiments a known 

 weight of silver was dissolved and precipitated as iodide ; 

 mean result, 100 Ag = 217.511 iodide. Extreme difference, 

 0.04. From these data Stas gets I = 126.84. The iodine 

 was purified by recrystallization as potassic iodate. The 

 methods employed by previous experimenters were ineffec- 

 tual. (Berzelius' Jahresbericht, ^^, 75 ; Bibl. Univ. de Genhe, 

 4,6, 1842, 367; also, Stas, Untersuch. iiber Chem. Prop., 153.) 



E. xMiLLON : 126.07 (0 = 16); 787.915 (0 = 100). 



Three experiments were made on the decomposition of 

 potassic iodate. The mean loss of oxygen was 22.473 per 

 cent ; extreme difference, 0.03. If K = 488.94, this gives I = 

 1580.93. In three experiments argentic iodate, which had 

 been dried for a long time at 200°, was employed, which lost 

 17.0467 per cent. ox3^gen; extreme difference, 0.03. If Ag 

 = 1349.01, these data give 1 = 1570.73. [Berzelius cites 

 this as an atomic weight determination ; Millon, however, 

 seems to have regarded it only as a confirmation of Ber- 

 zelius' number.] Millon prepared pure iodine by passing a 

 current of chlorine through a solution of KI till the precipi- 

 tated I was redissolved, and reprecipitating with an excess 

 of KI. {Amial de Chim. et de Phi/s., (3,) 9, 1843, 407.) 



V. A. Jacquelin : 125.6 (0 = 16); 785 (0 = 100). 



Determined by the analysis of iodic acid with silver. 

 The acid was prepared by the oxidation of iodine with 

 nitric acid of sp. gr. 1.5. The purity of the preparation 

 does not seem to have been tested. Ag = 1351. (JErd- 

 mann'sJourn. fur Prak. Chem.., 51, 1850, 458"; Annal de Chim. 

 et de Phys., (3,) 30, 1850, 332.) 



J. Dumas: 127 (0 = 16). 



Determined by the conversion of argentic iodide into 

 chloride in a current of dry chlorine. Two experiments 

 gave 127.04 and 127.01 for Ag = 108 ; CI = 35.5. In Gme- 

 lin-Kraut's Handbuch these data are recalculated for As- = 



