266 F. Wohler o« Tungsten. 



Heated in chlorine, a slight incandescence takes place ; chlo- 

 ride of tungsten which volatilizes, and of which I shall speak 

 hereafter, is formed. The other product of the combustion is 

 a greenish mass, which, treated with water, gives chloride of 

 sodium crystallized in cubes. The insoluble green powder is 

 a mixture of tungstic acid with a little oxide ; but the quantity 

 of the acid is much larger than that of the chloride and oxide 

 together. The result therefore seems to be, that the com- 

 bination contains oxygen, the whole quantity of which, before 

 the action of the chlorine, was distributed so as to form soda 

 and oxide of tungsten, and which, by the combination of the 

 chlorine with the sodium, entirely united with the tungsten in 

 order to form tungstic acid. I obtained exactly the same 

 result in employing the chlorine in a perfectly dry state; and 

 by avoiding the least mixture of atmospheric air with the chlo- 

 rine, in such manner that the formation of the tungstic acid 

 could proceed neither from the oxygen of the water nor from 

 that of the atmospheric air, 0*873 grain of the combination, 

 decomposed by chlorine, gave 0'157 grain of chloride of so- 

 dium = 0-089 grain of soda; consequently, 10*6 parts of soda 

 in 100 of the combination. But as I expected to have ob- 

 served that the half-fused state of the chloride of sodium pre- 

 vented the complete action of the chlorine on the combination, 

 I tried another manner of analysing this body; viz. by sulphur, 

 ' — which entirely decomposes it. 0*487 grain of the combina- 

 tion were melted with pure sulphur in a closed crucible of 

 porcelain. The resulting mass had the appearance of sul- 

 phuret of tungsten, and weighed 0*55 grain. No sulphuret 

 of sodium could be discovered, either with water or muriatic 

 acid. It was therefore treated with aqua-regia, which con- 

 verted it into pure tungstic acid. The fluid was made to eva- 

 porate on the acid, and then the whole mass ignited. The 

 tungstic acid, placed in a filter, was washed till all the sulphate 

 of soda which had been formed was dissolved. The pure 

 acid, dried and heated, weighed 0*4-5 grain. This quantity 

 corresponds with 86*2 parts of oxide of tungsten in 100 parts 

 of the combination : the remainder, therefore, is the quantity 

 of soda = 13*8 parts. It seems therefore that this combination 

 is composed of, 



Atoms. By calculation. By experiment. 



Oxide of tungsten ... 4 ... 87-81 . . . 86*2 



. Soda 1 ... 12*19 . . . 13-8 



100*00 100-0 



It will be seen that the oxygen of the soda is not half the 

 quantity which is required to convert the oxide of tungsten 

 into acid : for this purpose a part of the oxygen of the oxide 



of 



1 



