Broivning and Flint — Complexity of Tellurium. 347 



Art. XXXIY. — The Complexity of Tellurium ; by Philip E. 

 Browning and William R. Flint. 



[Contributions from the Kent Chemical Laboratory, Yale Univ.— cciii.l 



Although the consensus of opinion among chemists at 

 present seems to favor the homogeneity of tellurium* and an 

 atomic weight of 127*5, the recent work of Marckwald,f and 

 the last report of the International Committee on Atomic 

 W eights:}; seem to suggest that possibly the question of the 

 atomic weight at least has not been definitely settled. 



The work described in this paper was suggested by the 

 observation that when water is added in large amount to a 

 solution of tellurium tetrachloride, this compound is hydro- 

 lyzed and the greater part of the tellurous acid is precipitated, 

 while some of the tellurium remains in solution however large 

 the amount of water present. 



This observation was apparently first made by Berzelius§ 

 and later the method applied in a limited degree by Brauner| 

 and by Baker and Bennett^ to a process of fractionation. 



It was further observed by us that the tellurium remaining 

 in solution after the treatment with water and filtering may 

 be completely precipitated as the dioxide by heating to boil- 

 ing, treating first with ammonia and then with acetic acid in 

 faint excess, as described in a previous paper from this lab- 

 oratory.** 



This procedure was applied with the result to be described, 

 in order to determine whether by means of it any light might 

 be obtained upon the possible complexity of tellurium. 



About one hundred grams of crude tellurium, which had 

 been extracted by hydrochloric acid from electrolytic copper 

 residues, were subjected to a series of purification processes 

 such as have been commonly used for the purpose of prepar- 

 ing pure material. This crude preparation was first twice 

 fractionally precipitated by sulphur dioxide ; then fused in 

 portions, in hydrogen, with potassium cyanide, extracted with 

 water and precipitated from solution by a current of air. It 

 was next reprecipitated, by sulphur dioxide, from hydrochloric 

 acid solution ; was fused in hydrogen, and finally distilled, in 

 a current of hydrogen, from porcelain boats in a porcelain 

 tube. 



* Kothner, Ann., xcccxix, 1 ; Gutbier, Sitzungsber. phys-med. Soc. Erlan- 

 gen, xxxvii, 270 ; Lenher, J. Am. Chem. Soc, xxx, 387. 

 + Ber., xl, 4730. % J. Am. Chem. Soc., xxxi, 1. 

 §Ann. Chim. Phys. (2), lviii, 113. || J. Chem. Soc., lv, 382. 

 •fflbid., xci, 1849. ** This Journal, xxviii, 112. 



