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PROPERTIES OF TUNGSTIC ACID.

TUNGSTIC ACID,

PART LXXXVII.

This acid does not exist in nature in an unconibined state,but always united to lime, (tungstate of lime,) or with iron andmanganese, (wolfram.)

PROPERTIES OF TUNGSTIC ACID.

Tungstic acid appears in a pulverulent form, harsh to thetouch. It is tasteless and insoluble in water. It is incapable ofturning blue vegetable colours red, until it has been first render-ed soluble by ammonia. It is of a yellow colour, which becomesblue on being exposed to the light, (vol. I p. 125.) When putinto muriatic acid with tin, zinc, or iron, it yields to them itsoxigen, and hence the liquor becomes blue. It becomes also bluewhen boiled with sulphuric acid, and yellow with nitric or mu-riatic acid. Its specific gravity is about 6.12. It does not meltbefore the blow-pipe, but it becomes black when urged by theinterior flame. With glacial acid of phosphorus it produces atransparent blue glass, if the inner part of the flame be directedon them, which loses its colour on being removed to the exteriorpart of the flame. It neutralizes alcalies, and is thus renderedsoluble in water. Ammonia combined with it, or tungstateof ammonia, if dropped into lime-water, instantaneously throwsdown a precipitate which is tungstate of lime.

METHODS OF OBTAINING TUNGSTIC ACID.

Let one part of powdered tungstate of lime be digested inthree of nitric acid, till it acquires a yellow colour. Decant