TUNGSTEN. 61 7 



Sulphurets and chlorides of vanadium, corresponding with 

 the peroxide and vanadic acid, have likewise been formed.* 



SECTION V. 



TUNGSTEN AND MOLYBDENUM. 



TUNGSTEN. 

 Syn. WOLFRAM. Eg. 1183 or 94.8 ; W. 



This element exists in the form of tungstic acid in several 

 minerals, of which the most important are the native tungstate 

 of lime CaO,WO 3 , and wolfram, or the tungstate of manganese 

 and iron, MnO, WO 3 + 3 (Fe O, WO 3 ) . Its name tungsten means 

 in Swedish, heavy stone, and is expressive of the great density 

 of its preparations. 



Tungstic acid parts with oxygen easily, and may be reduced 

 in a glass tube, by means of dry hydrogen gas, at a red heat. 

 The metal is thus obtained in the state of a dense dark grey 

 powder, which it is necessary to expose to a very violent heat to 

 fuse into globules, for tungsten is even less fusible than man- 

 ganese. The metal, when fused, has the colour and lustre of 

 iron, and is not altered in air : it is, after gold and platinum, the 

 densest of the metals, the specific gravity of tungsten being 

 from I/. 22- to 17-6. When heated to redness, in the pulveru- 

 lent form, it takes fire, burns, and becomes tungstic acid. 

 Tungsten forms two compounds with oxygen, tungstic oxide, 

 WO 2 and tungstic acid, WO 3 . 



Tungstic oxide, WO 2 , 1383 or 110.8. Ais oxide is obtained 

 as a brown powder when tungstic acid is reduced by hydrogen 

 at a temperature not exceeding low redness. Tungstic acid 

 may also be deprived of oxygen in the humid way, by pouring 

 diluted hydrochloric acid over it, and placing zinc in the liquor ; 

 the tungstic acid then gradually changes into tungstic oxide, in 

 the form of brilliant crystalline plates of a copper-red colour. 

 No saline compounds of this oxide with acids are known. 

 When digested in a strong solution of hydrate of potash, it 

 dissolves, with the disengagement of hydrogen gas, and the 

 formation of tungstate of potash. 



* Berzelius, An. de Ch. et de Ph. t. 47, p. 337. 



