xygen and forms the
tetroxide. It is insoluble in water, but dissolves slowly in
hydrochloric acid. It possesses a feeble acid character, giving
metantimoniates when heated with alkaline carbonates.

Orthoantimonic acid, H3SbO4, is obtained by the decomposition of its
potassium salt with nitric acid (A. Geuther); or by the addition of
water to the pentachloride, the precipitate formed being dried over
sulphuric acid (P. Conrad, _Chem. News_, 1879, xl. 198). It is a white
powder almost insoluble in water and nitric acid, and when heated, is
first converted into metantimonic acid, HSbO3, and then into the
pentoxide Sb2O5. Pyroantimonic acid, H4Sb2O7 (the metantimonic acid of
E. Fremy), is obtained by decomposing antimony pentachloride with hot
water, and drying the precipitate so obtained at 100 deg. C. It is a
white powder which is more soluble in water and acids than
orthoantimonic acid. It forms two series of salts, of the types
M2H2Sb2O7 and M4Sb2O7. Metantimonic acid, HSbO3, can be obtained by
heating orthoantimonic acid to 175 deg. C., or by long fusion of
antimony with antimony sulphide and nitre. The fused mass is extracted
with water, nitric acid is added to the solution, and the precipitate
obtained washed with water (J. Berzelius). It is a white powder almost
insoluble in water. On standing with water for some time it is slowly
converted into the ortho-acid.

Compounds of antimony with all the halogen elements are known, one
atom of the metal combining with three or five atoms of the halogen,
except in the case of bromine, where only the tribromide is known. The
majority of these halide compounds are decomposed by water, with the
formation of basic salts. Antimony trichloride ("Butter of Antimony"),
SbCl3, is obtained by burning the metal in chlorine; by distilling
antimony with excess of mercuric chloride; and by fractional
distillation of antimony tetroxide or trisulphide in hydrochloric acid
solution. It is a colourless deliquescent solid of specific gravity
3.06; it melts at 73.2 deg. C. (H. Kopp) to a colourless oil; and
boils at 223 deg. (H. Capitaine). It is soluble in alcohol and in
carbon bisulphide, and also in a small quantity of water; but with an
excess of water it gives a precipitate of various oxychlorides, known
as powder of algaroth (q.v.). These precipitated oxychlorides on
continued boiling with water lose all their chlo