Additional Notice of Tzmgsten and Tellurium. 153 



muriatic dissolves the ore with energy, red fumes are evolved, and 

 generally a red solution obtained, from which ammonia preci- 

 pitates red oxide of iron abundantly. 



2. A heavy lemon-yellow powder remains, insoluble of course 

 in acids, but easily and completely soluble in warm ammonia. 



3. A dark powder, in diminished quantity, again appears, more 

 acid dissolves it in part, and again reveals the yellow powder, 

 which ammonia again dissolves, and so on, till nothing remains 

 but some portion of the gangue. 



4. The ammoniacal solution, which contains the oxide of 

 tungsten, is decomposed by acids and by heat, and instantly de- 

 posits a white heavy powder, becoming yellowish by standing, and 

 full yellow by heat. 



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 oxide of tungsten, or, as it is 

 sometimes called, tungstic acid. 



7. There were traces of manganese; and all the facts perhaps 

 justify the conclusion, that the ore is very similar to the ferrugi- 

 nous tungsten or wolfram. , 



S. The calcareous tungsten occurs in octohedral 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 opi- 

 nion of Col. Gibbs, we were withheld from announcing it, be- 

 cause 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 pos- 

 session, which are from Saxonv and Cornwall. 



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

 tablished the correctness of the above opinion,) we very unexpect- 

 edly discovered in some of the ores of tungsten, })roofs of the 

 existence of tellurium. The conclusion was induced by the phe- 

 nomena, for nothing was further from our expectations. 



Two fragments were pulverized hij an assislnnt, and ue there- 

 fore 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 tiuit of the 

 other pieces. 



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



slightly 



