118 ATOMIC WEIGHT DETERMINATIONS. 



J. J. Berzelius 129.03 (O = IG) ; 806.452 (0 = 

 100). • 



A known weight of metallic tellurium was oxidized with 

 nitric acid, the excess of acid being driven off by heat. It 

 was found that 100 Te gave 124.8 tellurious acid. {Poggend. 

 Ann., 8, 1826, 24.) 



J. J. Berzelius : 128.28 (O = 16); 801.76 (0 = 

 100). 



Determined as before but with purer material. Three 

 expenments were made, which gave 802.838, 801.786, 801.74. 

 Berzelius took the mean of the latter two. The tellurium 

 was prepared from tetradymite by heating with potassium 

 carbonate and olive oil in a closed crucible, dissolving the 

 potassium telluride so formed in water free from air, pre- 

 cipitating the tellurium by a current of air and distilling it 

 in a current of hydrogen. {Poggend. Ann., 22, 1834, 16.) 



K VON Hauer : 128.06 ( = 16). 



Determined from the mean of five experiments on the 

 precipitation of bromine with argentic nitrate from the 

 double bromide of potassium and tellurium. The bromine 

 contents was found to be 69.9236 per cent., for Ag = 108.1 ; 

 Br = 80; extreme difference 0.172. If K = 39.2, the 

 value follows. The salt was prepared by mixing tellurium 

 and potassic bromide in atomic proportions, adding water 

 and bromine, heating to drive off excess of bromine and 

 repeated recrystallization. {Erdmann^s Journ. fiir Prak. 

 Client., 73, 1858, 98; Sitz-Bericht der k. k. Acad.) 



J. Dumas : 129 (0 = 16). 



No details are given. [Annal. de Chim. et de Phys., (8,) 

 55, 1859, 129.) 



THALLIUM. 



Regnault determined the specific heat 'of thallium. It 

 agrees with an atomic weight of 204. {Gmelin-Kraut, I. c.) 



A. Lamy : 204 (0 = 16). 

 Three analyses of the chloride with argentic nitrate gave 



