Tungsten and Tellurium. 407 



5. This powder is infusible by the blow-pipe, but ignited 

 with borax in a platinum crucible, it became of a superb blue, 

 like smalt, or between that and Prussian blue. 



6. The quantity obtained was too small to make it conve- 

 nient to attempt its reduction to the metallic state ; no doubt 

 remained, however, that it was oxyd of tungsten, or as it is 

 sometimes called, tungstic acid. 



7. There were traces of manganese, and all the facts per- 

 haps justify the conclusion, that the ore is very similar to the 

 ferruginous tungsten or wolfram. 



8. The calcareous tungsten occurs in octahedral crystals, 

 but we have not before heard of this form in the ferruginous 

 species, which generally affects the prismatic forms. 



B. REMARK. 



We had been for some time inclined to believe, that the 

 above ore was ferruginous tungsten, but although fortified by 

 the opinion of Col. Gibbs, we were withheld from announcing 

 it, because the form of the crystals, the specific gravity, the 

 colour, and perhaps some other characters, were not perfectly 

 accordant with European descriptions, and with the specimens 

 in our possession, which are from Saxony and Cornwall. 



During the necessary chemical trials (which have, we trust, 

 established the correctness of the above opinion,) we very 

 unexpectedly discovered in some of the ores of tungsten, proofs 

 of the existence of tellurium. The conclusion was induced 

 by the phenomena, for nothing was farther from our expecta- 

 tions. 



Two fragments were pulverized by an assistant, and we 

 therefore cannot say whether they had any external characters 

 different from those of the other pieces ; they came, however, 

 from the same part of the vein, and their powder resembled 

 that of the other pieces. 



1. Digested in nitro- muriatic acid, a straw-yellow solution, 

 slightly inclining to green, was obtained, and a black powder 

 was left behind. 



2. More acid digested on this powder, gave a deep red solu- 

 laon of iron, and left the yellow oxyd of tungsten, which being 



