A Manual of the Chemistry of the Carbon Compounds

372 THE CHEMISTRY OF
By acting with ammonia on dinitranisic acid, it is converted into
methyl alcohol, and clirysanisic or dinitfoparamidtAenzoic add
C6H2(NOi!)2-< pQ%r crystallizing from alcohol in small rhombic
golden-yellow plates, melting at 259°,
Tin and hydrochloric acid reduce it to triamidohnzoic add
CgHJNH^gCOoH, which crystallizes from hot water in fine, shining
needles, with sulphuric acid, containing a trace of nitric acid, it
forms a deep-blue solution, like tiiamidolcnzene (see page 327). It
combines not only with bases, but also with acids,
Oxysalicylic Acid C8Hg-J £,Q ^.—To obtain this compound, mon-
iodosalicylic acid is boiled down with caustic potash, the residue
dissolved, in water, and acidulated with sulphuric acid. The solution
is then shaken with ether, and the ethereal solution evaporated.
Oxysalicylic acid crystallizes from water in shining needles, melting
at 183°, and decomposing when more strongly heated into carbon
dioxide, and a mixture of hydroquinone andpyrocatechitt. By adding
feme chloride to its aqueous solution, a deep-blue colour is produced,
which is changed into red by ammonia.
ProtocaUch%ie AM C0H3-< XQ •« has been obtained by acting with
fused potash on sulphoxybenzoic acid *, on bromo-, iodo-, and sulphopara-oxybemoic
acids; and on broinanisio, eugenic, and piperic acids.
It is also formed, together with pata-oxybenzoic acid, by rasing gumbenzoin,
guaiacum, dragon's-blood, and other resins with potash. It
is sparingly soluble in cold water, and crystallizes from boiling water
iu needles containing one molecule of water. It melts at 200°, and
is resolved by dry distillation into carbon dioxide, pyrocatechin and
hydroquinone. With ferric oliloride it gives a bluish-green colour,
which alkalis change into red.
As pyrocatechuic acid may be obtained from 1*3 oxybenzoic acid,
as well'as from 1-4 paraoxybenzoic acid, it follows that the hydroxyls
occupy the positions 3*4,
a Dioxylenzoic Acid GJS.A Q