24 ATOMIC WEIGHT DETERMINATIONS. 



J. Dumas: 112.24 (0 = 16). 



Determined by six experiments on the titration of cadmium 

 chloride with argentic nitrate. The mean of all the experi- 

 ments was Cd =: 56.12 ; extreme difi'erence, 0.49. The third 

 experiment varies considerably from the rest, and Dumas 

 seems inclined to omit it in the average. If it is left out, 

 the mean becomes 56.06; extreme difference, 0.29. Dumas 

 takes 01 = 35.5; Ag =: 108. The cadmium chloride was 

 prepared in two lots by solution of cadmium in chlorhydric 

 acid, evaporation and melting for several hours in a current 

 of chlorhydric acid gas. {Annal. de Chimie et de Physiquey 

 (3,) 55, 1859, 158.) 



E. LexXssen : 112.06 (0 = 16). 



Three experiments were made on the decomposition of 

 cadmium oxalate, the salt and the resulting oxide being 

 weighed. The mean result was Cd =: 56.03 ; extreme dif- 

 ference, 0.19. C =: 6. The oxalate was prepared from pure 

 chloride by precipitation with oxalic acid, washing and dry- 

 ing at 150°. It was carefull}^ tested, and was found to be 

 anhydrous. [Erdmami's Journ. far Prak. Chemie, 79, I860, 

 281. 



CESIUM. 



The great similarity between caesium and the other alka- 

 line metals renders the deduction of its atomic weight from 

 its equivalent sufficiently certain. 



KiRcniiOFF and Bunsen : 123.35 (0 = 16). 



Determined by three experiments on the analysis of the 

 chloride with argentic nitrate. The value is the mean ; 

 extreme difference, 0.13. The caesium was separated from 

 the other alkalies by extracting a mixture of oxides and car- 

 bonates with alcohol. It was converted into chloride by 

 precipitation with platinum chloride, reduction of the dou- 

 ble chloride in h3-drogen and solution. These operations, 

 were repeated until the caesium salt gave sensibly the same 

 results after successive purifications. Its purity was also 

 tested spectroscopically. Silver was taken at 107.94, and 

 chlorine at 35.46. {Poggend. Annal., 113, 1861, 363.) 



