393 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



latter was distilled off and collected in a solution of potassium iodide. 

 Iodine was set free and determined by titration with a tenth normal 

 thiosulphate solution. If W = the weight of telluric acid, and n the 

 number of cubic centimetres of the thiosulphate solution, the atomic 

 weight of tellurium is given by the subjoined formula : 



Te=: 20000 W_H^O^ 



n 



The first term on the right of the equation obviously represents the 

 molecular weight of HgTeOe. The figures are as follows: ' 



Mean,- 229.270, ± .0425 

 Hence Te = 127.223. 



Secondly, Heberlein employed Staudenmaiei-'s method of reducing 

 HgTeOs to TeOa by careful heating in a glass bulb : 



Mean, 69.381, ± .0115 



Hence Te = 126.72. 



Finally, tellurium dioxide was reduced to tellurium by heating in a 

 current of hydrogen in presence of silver. Heberlein's two experiments 

 are as follows : 



Mean, 79.8745, ± .0034 



Hence Te = 127.002. Heberlein's determinations assign low values to 

 the atomic weight of tellurium. 



Steiner's determination * of the atomic weight was made by combustion 



^ The formula given by Heberlein probably involves the old atomic weights ot chlorine and 

 iodine. With modern atomic weights the value for Te would be raised. The data as printed are, 

 however, incomplete. A correction would be uncertain, and the probable error of the deter- 

 minations is so high that the change could exert no appreciable effect upon the final combination 

 of values. 



= Ber. Deutsch. chem. Ges., 34, 570. 1901. 



