162 On the Preparation of Large Quantities of Tellurium. 



already communicated the results to the Eoyal Society.' 55 ' Many, if 

 not most of these ores, contained traces of tellurium. 



Tellurium has a marked tendency to associate itself with bismuth, 

 as silver may be said to do with lead, or phosphorus with iron, and 

 accordingly the crude bismuth extracted from these ores invariably 

 contained small quantities of tellurium, which was reduced together 

 with the bismuth, and was found to exist in it in a greater proportion 

 than in the ores. 



The presence of even minute traces of tellurium in bismuth being 

 sufficient to render this metal unsaleable, it is necessary to remove 

 every portion of the tellurium whilst refining the crude bismuth. The 

 alkalies containing the tellurium resulting from the refining of the 

 crude bismuth were thrown aside, and were left for future investigation. 



I have now been able to treat these alkaline residues, and have ex- 

 tracted from them a substantial amount of metallic tellurium, weighing 

 26 kilos. This amount of tellurium was produced from 321 tons of 

 mineral containing an average amount of 22*50 per cent, of bismuth. 



The amount of metallic tellurium obtained corresponds to an average 

 of 0'007 per cent, of the original mineral. 



The 26 kilos, of metallic tellurium was obtained by soaking the 

 telluricle alkalies, resulting from refining the telluric bismuth, in hot 

 water — acidifying these solutions with hydrochloric acid, and preci- 

 pitating the tellurium with sodium sulphite. A crude mixture of 

 bismuth and tellurium was thus obtained, the tellurium forming about 

 47*5 per cent, of the crude metal. 



This was dissolved in nitric acid, and again treated in the same way, 

 -and yielded the amount of tellurium represented by the 26 kilos. This 

 shows on analysis : — 



The appearance of the metal when broken shows a crystalline frac- 

 ture, of needle-like structure, and of bright metallic lustre. It does 

 not readily tarnish in the air at the ordinary temperature. If slowly 

 cooled, a crystalline form very much resembling that of bismuth is 

 obtained. 



Its specific gravity is 6*27, as against 6'23 the density of uncom- 

 pressed tellurium found by Spring. 



* <Koy. Soc. Proc.,' vol. 42, 1887, p. 89; vol. 49, 1890, p. 78 ; and vol. 52, 1893, 

 p. 467. 



Tellurium 

 Bismuth 

 Copper ... 



Iron 



Loss 



97-00 

 2-15 

 0-65 

 0-10 

 0-10 



100-00 



