88 
Book II. 
Does not 
deserve the 
name of 
acid. 
Nungsras. 
ACIDS. 
acid dissolves the lime, and the ammonia combines with 
the tungstic acid. The ammoniacal solution, when satu 
rated with nitric or muriatic acid, deposites a white 
powder, which is the tungstic acid of Scheele. 
This powder has an acid taste, it reddens vegetable 
blues, and is soluble in 20 parts of boiling water. The 
De Luyarts have demonstrated, that this pretended acid 
is a compound of yellow oxide of tungsten, the alkali 
employed to dissolve it, and the acid used to precipitate 
it. Thus, when prepared according to the above de 
scribed process, it is a compound of yellow oxide, am 
monia, and nitric acid. Their conclusions have been 
more lately confirmed by the experiments of Vauque 
lin and Hecht. This substance must therefore be erased 
from the class of acids, and placed among the salts. 
The real acid of tungsten is a yellow powder; the 
method of procuring which, and its properties, have 
been already described under the denomination of Tel 
low Oxide of Tungsten*. It ought rather, as Vauque 
lin and Hecht have properly remarked, to be classed 
among the oxides than the acids ; for it is insoluble in 
water, tasteless, and has no effect on vegetable blues. 
It agrees with the acids indeed in the property of com 
bining with alkalies and earths, and perhaps also with 
some metallic oxides, and forming with them salts 
which have been denominated tungstats; but several 
other metallic oxides, those of lead, silver, and gold, 
for instance, possess the same property. These oxides 
therefore may be called acids with as much propriety 
as the yellow oxide of tungsten. 
F Vol. L.p.215.