A Manual of the Chemistry of the Carbon Compounds

THE CARBON COMPOUNDS. 241
By the action of acetic acid upon potassium deoxalate the compound
CfH4K,Og + H2O is produced. The coraespoudiug acid C6H6O,
is tribasic, and can be obtained by decomposing the lead salt with
hydrogen sulphide; it is a crystalline deliquescent mass.
The formation of deoxalic acid from oxalic acid can be easily explained.
The latter acid is first reduced to glyoxylic acid, of which
three molecules combine with hydrogen, forming deoxalic acid :—
AOH
2 ~ OH.OH
no.o-(CH(OH)-C02H
co,:
This formula explains the decomposition of the acid into tartaric
and glyoxylic acids. Deoxalic acid is tribasic, but as the barininand
silver salt show, one atom of hydrogen in one of the alcoholic
hydroxyl groups can also be replaced by a metal
umc ACID C6H«N4O8.
Uric acid occurs in the urine of all animals. The excrements of
serpents consist almost entirely of uric acid and ammonium urate,
and those of birds and insects contain a large quantity of these compounds.
Human urine, and that of animals feeding on flesh or
corn, contain only a small quantity of uric acid, and still leas is
found in the urine of herbivorous animals.
Being very sparingly soluble it often separates from urine as a
crystalline precipitate; if this takes place in the bladder, gravel and
stones are produced. In certain diseases, as in gout, acid sodium
urato crystallizes out in the muscles and between the joints.
For the preparation of uric aoid either guano or excrements of serpents
are used The exorements, or guano which has been previously
treated with dilute hydrochloric acid, are dissolved in dilute hot
potash-solution, and the uric acid precipitated by dilute sulphuric acid.
Uric acid is a white orystalline powder, without taste and smell; it
is almost insoluble in cold water, and only sparingly in boiling water,
In alcohol and ether it is insoluble, but it is readily soluble in hot
concentrated sulphuric acid, and separates out again from thia solution
on addition of water,
C