A Manual of the Chemistry of the Carbon Compounds

THE CABBON COMPOUNDS. 223
in oarbon compounds containing oxygen the carbon group is much
more readily decomposed than in compounds containing no oxygen,
and the two succinic acids show that such a separation of carbon
atoms takes place more readily, the nearer together the oxygen atoms
are grouped in the molecule.
MALIC ACID C4H,0,
Malic acid and tattaric acid, two compounds winch are very widely
distributed in the vegetable kingdom, are very nearly related to succinic
acid, bearing similar relations to the latter as glycollic acid does
to acetic acid •, and therefore, although they have to be regarded as
compounds of triad and tetrad-radicals, they will most conveniently
be treated here.
Malic Acid is found in most kinds of sour fruit, chiefly in unripe
apples, and in the berries of the mountain ash, and also in currants,
sour cherries, in the stalks and leaves of rhubarb, &c. Sweet cherries
contain neutral potassium malate.
The acid is readily obtained from rhubarb-stalks or from the
berries of the mountain ash at the time when they begin to ripen.
The stalks or berries are ground to a pulp and pressed out. The
juice is boiled and nearly neutralized with milk of h'me. On boiling
the filtered liquid for soine time calcium malate separates out as a
granular powder, which is washed with cold water and dissolved in
liot dilute nitric acid, On cooling, acid calcium malate is obtained
in large crystals, which are separated from the mother-liquid, and
dissolved in water. On adding lead acetate to this solution lead
malate is precipitated, which is washed and then decomposed by
hydrogen sulphide. Malic acid is obtained on evaporating the
aqueous solution in groups of small colourless and deliquescent
prisms, having a strong and agreeable sour taste. Its solution, tune
the plane of polarized light to the left; whilst the acid obtained
artificially from sucoinio acid is optically inactive.
On heating malic aoid with concentrated hydriodic acid, it is
reduced to succinio aoid s—
C8H3(OH)(CO?H)a + 2HI = C2H4(CO8H)? + HaO + I,
When malic acid is heated with hydrobromic acid it is converted
into monobroinosuccinic acid!—
^ + HBr - C2H3Br(COaH)g +
The malates of the alkali-metals are readily soluble in water.
Normal Calcium Malale Gfififia + 2H4O crystallizes in large
plates', on toiling its aqueous solution for some time it separates
as a granular powder C4H4OsCa + H4O. Acid calcium, malate