904 On Tungsten. (Serr. | 
of purity. It is to be washed, and gently dried, upon which it 
assumes a fine yellow colour. 
3. In order to obtain pure tungstate of ammonia, it is necessary 
to have in our possession pure oxide of tungsten. Respecting this 
also further details will be given hereafter. 
(B.) 
Experiments on the best Method of obtaining Tungsten from Tung- 
stic Oxide by means of Tungstate of Ammonia. 
Exper. 14.—30 gr. of the tungstate of ammonia formed in the 
first experiment by treating the impure oxide of tungsten that had 
been exposed to a red heat with ammonia were put into a small 
glass, which was placed in a crucible, and surrounded with charcoal 
powder. The whole was exposed for an hour to a strong red heat. 
The interior of the glass, when cold, exhibited a brownish red, 
almost copper-coloured, matter, of a flocky appearance, and con- 
siderably specific gravity. I could only consider it as a peculiar 
oxide of tungsten, which hitherto had not been observed by che- 
mists. 
The brown oxide thus obtained was put into a Hessian crucible 
rubbed over with some charcoal powder. Charcoal powder was laid 
over the oxide, and the crucible, being covered by another, was 
exposed for half an hour to a strong white heat raised by a double 
bellows. When the crucible was cold, the brown oxide appeared 
to have been converted into a loose pretty heavy substance, which 
here and there exhibited the metallic lustre, and had an iron-grey 
colour. When strongly rubbed and polished against hard and 
smooth bodies, its metallic lustre became still more distinct, and its 
colour was intermediate between that of iron and tin. The grains 
were slightly agglutinated together, and the portion that lined the 
sides of the crucible appeared to be so more distinctly than the rest. 
This reguline mass seemed to have been softened, and showed evi- 
dently that a stronger heat than the preceding would have melted 
it completely. ‘To see whether it was possible to fuse it, the fol- 
lowing experiment was made. 
Exper. 15.—20 gr. of the iron-grey metal mass were put into a 
crucible lined with charcoal powder, as in the preceding experi- 
ment, covered with a layer of charcoal powder half an inch thick, 
and then exposed for an hour to the strongest heat that could be 
raised in the blast furnace. No real fusion took place, but a kind 
of cementation into a mass which was easily reduced to powder, and 
this union seemed to be strongest along the sides of the crucible. 
The colour, appearance, and every thing else, were as in the pre- 
ceding experiment. 
It follows from these experiments that tungstate of ammonia, 
when destroyed by a red heat, leaves behind it a reddish brown 
oxide, and. that this oxide is deoxidized by charcoal powder long 
before the metal produced is melted. 
Exper. 16,—130 gr. of tungstate of ammonia of the same kind 
