992 On Tungsten. (SEPT. 
immediately in ammonia, with the exception of a very small portion 
of a light white substance in powder. 
This success excited in me the strongest hopes of succeeding in 
my object by this method, and led me to suspect that in all proba- 
bility the tungstic oxide had been rendered insoluble in ammonia 
by exposing it to a red heat. I resolved to prove the truth of this 
conjecture.in the following way. ‘ 
The tungstic oxide obtained by the preceding process was well 
washed twice successively, each time with 24 oz. of water, and by 
that means freed from the saltpetre formed during the process, and 
from the excess of acid, and obtained in a state of purity. When 
collected on the filter, and well dried, it weighed 2 oz. 2dr. The 
liquid retained a portion of oxide so light, and in a state of such 
fine division, that it could not be retained upon the filter, but passed 
through it how many times soever it was filtered. This yellowish 
milky liquid, being set aside for three months, allowed the oxide . 
gradually to subside. When collected and dried, it weighed 2 dr. 
1 gr. 
With this oxide, which had a lemon-yellow colour passing into 
yolk of egg colour, the following experiments were made, in order 
to determine its solubility in caustic ammonia. 
Exper. 11.—Two ounces of pure caustic ammonia, of the 
strength which it has when prepared according to the formula given 
by me in the Almanac for Chemists and Apothecaries of 1803, 
p. 20, were put in contact with the whole of our dry tungstic oxide, 
loz. and 20 gr. dissolved in the ammonia, or were at least con- 
verted into a white pulverulent matter. 
From the phenomena it was evident that a much greater propor- 
tion of the oxide would have dissolved, or been converted into a 
white powder, by the quantity of ammonia employed, more pro- 
bably than all that I had in my possession. I determined, therefore, 
to ascertain in another experiment upon a smaller scale the capacity 
of ammonia in dissolving tungstic oxide, or converting it into a 
white powder. . 
In the mean time I separated by the filter the white, light, slimy 
matter, which existed in the ammoniacal solution. It was washed. 
on the filter with 11 oz. of caustic ammonia, and then dried. Its 
weight amounted to 80 gr. It exhibited the properties of a qua- 
druple compound of ammonia, potash, tungstic oxide, and muriatic 
acid, with some oxide of iron and silica from which the tungstic 
oxide had not been freed. ‘The ammoniacal solution was evaporated 
to dryness in a porcelain vessel. 300 gr. of tungstate of ammonia 
were obtained, though by an unlucky accident a third part of the 
solution had been lost. 
Exper. 12.—50 gr. of a solution of caustic ammonia were 
brought in contact with 80 gr. of oxide of tungsten. The mixture 
became stiff; and it was with difficulty that some remains of the 
yellow oxide could be perceived mixed with the white mass. , By 
agitation in a considerable quantity of water, and still better by the 
