A Manual of the Chemistry of the Carbon Compounds

TEE CHEMT8TRY OF
solution decomposes on spontaneous evaporation, and leaves tarlrmic
add or oxymaUnvic acid 0$H4O6 beliind:—
CO.OH
I CO.OH
CHKO. I
CI
I " - CH.OH + CO8 + N2O8
CHNO. '
I CO. O.OH
CO.OH
On heating an aqueous solution of nitrotartaric acid it is oxidized
to oxalic acid. Ammonium sulphide acts on it as on other nitric
ethers, tartaric acid being formed again.
RACKMIC ACID AND LEVOTAUTARIC ACID.
Racemic acid occurs together with tartaric acid in several kinds of
tartar. It crystallizes in transparent rhombic prisms C4H6O8 + H4O,
and is rather less soluble than tartaric acid; but in all other respects
a very great resemblance exists between these two acids and their
salts, the chief difference being that calcium raoemate is insoluble in
-1b
Flo. 10. Flo. 11.
ammonium salts, and further, that crystallized normal racemates, containing
one metal, do not exhibit heniiliedral faces, like the crystals
of the corresponding tartrates.
By neutralizing acid sodium racemate with ammonia, and allowing
the solution to crystallize slowly, two varieties of crystals tiro
obtained, each of them containing hemihedral faces (5) (see Figs. 10
and 11), equal in number, and exactly similar in form, but developed
on opposite sides of the two crystals, so that eaoh of them may he
regarded as a reflected image of the other. On carefully separating
these crystals and converting them into the acids, two acids are
obtained, one being common or dextrotartaric acid, and the other a
very similar acid called levotartaric add, because it possesses lefthanded
polarization. On dissolving equal parts of the two acids in
.fa