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SMITHSONIAX MISCELLANEOUS COLLECTIONS 



VOL. 54 



atomic weight of telhiriuin, among tliem being the gynthetie preparation 

 of silver, copper and gokl tellurides. and the basic sulphate, TcjSO^. 

 None of these methods gave sufficiently concordant results, and they 

 were therefore abandoned. The oxidation of tellurium to dioxide by 

 means of nitric acid was also unsatisfactory, but a series of oxidations 

 with, aqua regia gave data as follows. The third column contains the 

 percentage of tellurium in the dioxide: 



Mean, 79.711, ± .0239 



Hence Te = 125.72. 



In a single analysis of the dioxide, by reduction with S0„, 2.5489 

 grammes TeOo gave 2.0374 of metal. If we give this experiment the 

 weight of one observation in the synthetic series, the percentage of tel- 

 lurium foimd by it becomes — 



79.932, ± .0534 



Hence Te = 127.46. . 



Brauner's best results were obtained from analyses of tellurium tetra- 

 bromide, prepared from pure tellurium and pure bromine, and after- 

 wards sublimed in a vacuum. This compound was titrated with standard 

 solutions of silver, and three series of experiments, made with samples 

 of bromide of different origin, gave results as follows. The TeBr^ equiva- 

 lent to 100 parts of silver appears in the third column : 



