Its soluble neutral salts change blue litmus
paper to red, and are converted, by admixture of water, into
insoluble basic and soluble acid salts.

Antimonious acid (antimoniate of sesquioxide of antimony, Sb^{2}O^{3}
+ Sb^{2}O^{5}) is of a white color, but, when heated, of a light
yellow color, but changes to white again when cold. It is infusible
and unaltered by heat. It forms a white hydrate, and both are
insoluble in water and nitric acid. It is partly soluble in
hydrochloric acid, with the application of heat. The addition of water
causes a precipitate in this solution.

_Antimonic Acid _(Sb^{2}O^{5}).--In the pure state this acid is a
light yellow-colored powder. Its hydrate is white, and is insoluble in
water and nitric acid. It is sparingly soluble in hot concentrated
hydrochloric acid. It forms salts with every base, some of which are
insoluble, and others sparingly so. Notwithstanding that antimonic
acid is insoluble in water, it expels the carbonic acid from the
solutions of the carbonates of the alkalies. Antimonic acid and its
hydrate changes moistened blue litmus paper to red.

_Behavior of Antimony and its Oxides before the Blowpipe._

_Metallic Antimony_ fuses easily upon charcoal. When heated to
glowing, and then removed from the flame, it continues to glow for
awhile, and produces a thick white smoke. The vapor crystallizes
gradually, and coats the assay with small crystals which iridesce like
mother of pearl (sesquioxide of antimony). It is not volatile at the
temperature of melted glass. Ignited in an open glass tube, it burns
slowly with a white vapor, which condenses upon the cool part of the
tube, and exhibits some indications of crystallization. This vapor
consists of the sesquioxide, and can be driven by heat from one place
to another, without leaving a residue. If the metallic antimony
contains sulphide of antimony, there is a corresponding portion of
antimonious acid produced, which remains as a white sublimate after
the sesquioxide is removed.

_Sesquioxide of antimony_ melts easily, and sublimes as a white vapor.
It may be prepared by precipitating and drying. When heated, it takes
fire previous to melting, glows like tinder, and is converted into
antimonious acid, which is now infusible. When heated upon charcoal in
the flame of reduction, it is reduced to the metallic state, and
partly volatilized. A white vapor sublimates upon the charcoal, while
the external flame exhibits a gree