MOLYDBENUM. 619 



The tersulphuret of tungsten has a certain degree of solubility 

 in water containing no saline matter, and is a strong sulphur 

 acid. The salt KS, WS 3 forms pale red crystals. Two parts 

 of this sulphur salt dissolved in water with one part of nitre, 

 give large and beautiful ruby-red crystals of a double salt, 

 KS,WS 3 + KO,NO 5 . 



Bichloride of tungsten, WC1 2 , is formed when metallic tung- 

 sten is heated in chlorine gas. It condenses in dark red needles, 

 which are very fusible and volatile. This chloride is decom- 

 posed by water, and tungstic oxide with hydrochloric acid 

 formed. 



Terchloride of tungsten, W C1 3 , is produced at the same time 

 as the last compound, and also when the sulphuret of tungsten 

 is heated in chlorine gas. It forms a sublimate of beautiful red 

 crystals, which are resolved by water into tungstic and hydro- 

 chloric acids. A chlorotungstic acid, or double compound of 

 terchloride of tungsten and tungstic acid, WO 2 Cl, or WC1 3 -f 

 2WO 3 , is prepared by heating tungstic oxide in chlorine gas. 

 It condenses in yellow crystalline scales : when suddenly heated, 

 it is resolved into tungstic acid, bichloride of tungsten, and 

 chlorine. Another compound is known, 2 WC1 3 -f WO 3 (Bonnet.) 



MOLYBDENUM. 

 Eg. 598.5 or 47.96, Mo. 



This metal is closely allied to tungsten. Its native sulphuret 

 was first distinguished from plumbago by Scheele, in 1778 ; and 

 a few years afterwards, molybdic acid, which he had formed, was 

 reduced, and molybdenum obtained from it, by another Swedish 

 chemist, Hjelm. The name molybdenum is derived from the 

 Greek term for plumbago. 



The oxides of molybdenum are easily reduced, when exposed 

 to a strong heat in a crucible lined with charcoal, but the metal 

 itself is very refractory. Bucholz, who obtained it in rounded 

 buttons, found it to be a white metal, of density between 8.615 

 and 8.636". It is not acted upon by hydrochloric, hydrofluoric, 

 or diluted sulphuric acid ; but is dissolved by concentrated 

 sulphuric acid, by nitric acid, and aqua regia. Hydrate of 

 potash does not dissolve this metal by the humid way. It 

 combines in three proportions with oxygen, forming molybdous 

 oxide, MoO, molybdic oxide, MoO 2 , and molybdic acid, MoO 3 . 



