To remove it, Oxland fuses the ore with a certain proportion of carbonate of soda, which suffices to convert the tungsten into soluble alkaline tungstate, without producing noteworthy quantities of soluble stannate from the oxide of tin; the tungstate is easily removed by treatment with water.
A blue bronze, Na2W5015, forming dark blue cubes with a red reflex, is obtained by electrolysing fused sodium paratungstate; a purple-red variety, Na2W309, and a reddish yellow form result when sodium carbonate and sodium tungstate are heated respectively with tungsten trioxide and tinfoil.
Ammonia does not react with tungsten or the dioxide, but with trioxide at a red heat a substance of the formula W 5 H 6 N 3 0 5 is obtained, which is insoluble in acids and alkalis and on ignition decomposes, evolving nitrogen, hydrogen and ammonia.
But not only is the combining power or valency (atomicity) of the elements different, it is also observed that one element may combine with another in several proportions, or that its valency may vary; for example, phosphorus forms two chlorides represented by the formulae PC1 3 and PC1 51 nitrogen the series of oxides represented by the formulae N 2 0, NO, (N203), N 2 O 4, N205, molybdenum forms the chlorides MoC1 2, MoC1 3, MoC1 4, MoC1 5, MoCls(?), and tungsten the chlorides WC1 2, WCl 4, WC1 5, WC16.
The hexafluoride, WF 6, is a very active gaseous compound, which attacks glass and metals, obtained from tungsten hexachloride and hydrofluoric acid (Ruff and Eisner, Ber., 1905, 38, p. 74 2).
Hjelm in 1783, and tungsten by Don Fausto d'Elhuyar; manganese was isolated by J.
Thus, hydrogen unites with but a single atom of chlorine, zinc with two, boron with three, silicon with four, phosphorus with five and tungsten with six.
Similar potassium tungsten bronzes are known.
Again, when tungsten hexachloride is converted into vapour it is decomposed into chlorine and a pentachloride, having a normal vapour density, but as in the majority of its compounds tungsten acts as a hexad, we apparently must regard its pentachloride as a compound in which an odd number of free affinities are disengaged.
It is a member of the sixth group in the periodic classification of the elements, being included in the natural family of elements containing molybdenum, tungsten and uranium.