F. Wohler on Tungsten. 265 



water. It is necessary to employ all these pi'ecautions if the 

 combination is to be obtainecl in its pure state. 



The super-tungstate of soda may be prepared by adding 

 tungstic acid to the neutral salt while melting, until the last 

 portions will no longer dissolve. 



The yellow metallic substance, which I shall show to be a 

 combination of oxide of tungsten with soda, is crystallized in 

 regular cubes, which are laiger in proportion to the slowness 

 of the operation by which they have been formed. Sometimes ca- 

 vities are found in the reduced saline matter, the sides of which 

 are formed by an aggregation of small and very brilliant cubes. 

 This combination has, as I said before, a perfect metallic bril- 

 liancy even when rubbed on paper ; its colour scarcely differs 

 from that of gold, and on looking at such a crystalline powder 

 in the sun, it displays a beauty and a brilliancy possessed by few 

 chemical preparations. Suspended as a fine powder in water, 

 and looked at towards the sun, it is, like gold, transparent and 

 of a green colour. 



It is decomposed by no acid whatever, not even by boiling 

 aqua-regia. Nothing but concentrated fluoric acid decomposes 

 and dissolves it. The solutions of pure alkahes have no effect 

 on it. Heated in contact with atmospheric air, it changes co- 

 lour, softens, melts in a uniform manner; and around the sub- 

 stance submitted to the experiment is formed a white enamel 

 which is soluble in water. By then adding an acid, tungstic 

 acid is precipitated. But the whole mass of the combination is 

 never converted into that enamel, — there always remains a part 

 in the middle which does not decompose. 



This decomposition is not more complete even in oxygen 

 gas, although it be accompanied by combustion. Here, too, 

 the fusible mass which is produced, forms a stratum which 

 hinders the action of the gas on the interior portions. In a 

 vacuum the combination may be heated without decomposition. 

 It appears therefore very probable that the fusible substance 

 formed in this case is nothing else but tungstate of soda, and 

 that this new body contains at least tungsten and sodium ; 

 but it was difficult to decide if those bodies were in the oxidated 

 or in the metallic state. The property of not being decom- 

 posed by aqua-regia was opposed to its being regarded as an 

 alloy of tungsten and sodium, and its metallic properties ren- 

 dered it difficult to admit that this combination was oxidated. 



As this combination is not decomposed by the most pow- 

 erful re-agents, I was obliged to seek for other means; and found 

 that it was decomposed by chlorine, — but only on its being 

 strongly heated in this gas ; otherwise there would be no rea- 

 Bon why it should not also be decomjiosed in aqua-regia. 



Vol. 66. No. 330. Or/. 1825. LI Heated 



