214 Flint — Researches tipon the Complexitxj of Tellurmm. 



The concordance of these resnlts is sufficiently close to 

 indicate that the two prejiarations of fraction ten were prac- 

 tically constant in composition. Experiment 7 in the 

 above table was performed in parallel with experiment 5 of 

 Table I. 



A comparison of the mean values given in the four preceding 

 tables shows a remarkable lo\vering of the atomic weight with 

 the progress of the fractionation. In considering the difference 

 between the mean result, 124-3, of Table IV, and that, 125"4:, 

 of Table III, it should be noted that, since the material which 

 gave the latter figure was derived from the filtrate of fraction 

 eight, it was to have been expected tbat its atomic weight 

 would be higher than that of fraction eight itself. Owing to 

 the small quantity remaining of fraction ten, it was impossible 

 to make another direct fractionation. But the dioxide pro- 

 dxiced in the experiments of Table IV was dissolved in 

 hydrochloric acid and the hydrolysis repeated once more, the 

 pi'ecipitate being converted to basic nitrate. The basic nitrate 

 experiments gave 124:'62 and 124.61:, but these figures cannot 

 be accepted as conclusive. In the first place, they were made 

 upon material which had already been used for previous deter- 

 minations, in which the dioxide formed had been heated in 

 platinum up to fusion. During the course of the basic nitrate 

 experiments described in this paper, a progressive, but minute, 

 loss of weight was observed in the platinum crucibles used. 

 This fact suggests the possibility that the tellurium may have 

 become contaminated with a little platinum, which would 

 of course raise the atomic weight found in these two experi- 

 ments. And second, while these two experiments were in 

 progress, an extreme humidity unfortunately characterized 

 the weather. The tendency of this condition would be to 

 increase the atomic weight also, since traces of moisture absorbed 

 b}' the basic nitrate during those short, but necessary, periods in 

 which it was out of the heaters and desiccator for the purpose 

 of weighing, would tend to produce hydrolysis to dioxide, and 

 the nitric acid liberated from the compound would be expelled 

 in the next heating. This also would increase the value found 

 for the atomic weight. It is therefore at present impossible 

 to conclude with certainty that the figure 124:'3 represents the 

 true atomic weight of the element tellurium, since the value 

 may perhaps lie a little below this number. 



Conclusion. 



Using the customary methods of purification, a large quantity 

 of tellurium has been prepared. By the basic nitrate process, 

 this has been shown, in live experiments with 20 grams of 



