A Manual of the Chemistry of the Carbon Compounds

404 TEE CHEMISTRY OP
Mellitic acid is readily soluble in water and alcohol, and crystallizes
in colourless needles, possessing a strong sour taste. It is a
very stable body, which is not acted upon by hot concentrated snlphuric
acid or nitric acid, nor by bromine or hydriodie acid. By distilling
it with quicklime, it is resolved into benzene and carbon
dioxide:—
C12H8O12 = 0 ^ + 600,
It is consequently hexacarboxybmzene C6(CO2H)a, or the last term of
a series of acids, which are derived from benzene by replacing one
atom of hydrogen after the other by carboxyl, and all of which are
resolved by heating them with lime into carbon dioxide and benzene.
Aminmiium MdlitaU C6(C08NH4)6 + 9H2O forms large rhombic
prisms.
Barivm Mellitate C6(CO3)8Baj+ 3HjO is obtained by adding barium
chloride to a solution of the barium salt as a white precipitate, which
soon changes into small platea
Aluminium MdlitaU C^CO^Alg -f 18HjO exists as honey-stone in
large, yellow, square octahedrons.
Silver MdlitaU C^COgAg),, is a white crystalline precipitate, which
by heat is resolved into metallic silver and carbon monoxide.
Besides these normal salts, there exist also salts, containing two
metals and acid salts:—
CO
Ethyl Mellitate Ca(CO4.C2H^a is obtained by the action of ethyl
iodide on the silver salt, and forms large colourless crystals, melting
at 69°.
Mellilia Chloride C^OOCl), is formed by heating the acid with
phosphorus peutachlonde. It is a crystalline mass, which is slowly
dissolved by boiling water, with the formation of hydrochloric acid
and mellitic acid.
Mellimide, or Pammide CuH,NqOt is produced, together with ammonia
and the ammonium salt of eucliroic acid, by heating ammonium
mellitate. It is a white, amorphous powder, which is insoluble
ill water and alcohol, and is converted into acid ammonium mellitate
CO(CO?H)?(CO?NH4)3 by heating it with water to 200°.
Ewhrow AM O^U^NgOg forms colourless prisms, which are sparingly
soluble in water. By the action of zinc or other reducing
agents, it is converted into a deep-blue, insoluble substance, called
ewhrone, which dissolves in alkalis with a deep-purple colour, and in
contact with air is oxidised again to euchroic acid. When euchroic
acsid is heated with water to 2U0°, it yields the acid salt CJOOM),
(00 NH4)a. > "
The constitution of these bodies is explained by the following
formula?:—