at 150° without leaving any residue. Heated with strong sulphuric acid it
splits up into carbon dioxide, carbon monoxide and water.
Symptoms.—Oxalic acid has both a local and a remote action on the
system. It acts locally as corrosive, when administered in a large quantity
and in a solid or concentrated form but, when taken in a weaker solution or
in combination, acts locally as irritant and the nervous symptoms are more
evident. It also acts as a poison, wl^fcgpplied to a wound.
The symptoms begin immediateif^B soon after taking a large dose of
the concentrated acid. These are a very sour acid taste, thirst, pain and
burning in the mouth, throat and stomach, extending over the whole
abdomen. Vomiting soon sets in. It very often persists till death. The
ejected matter contains altered blood and mucus, and appears greenish-
brown or black, resembling coffee grounds. In some cases vomiting may not
occur or may be delayed for some time. Tenesmus is present, but purging}
is rare, unless the case is prolonged for some time. The urine is diminished
in quantity and may be suppressed for two or three days. Later, it increases
in quantity and contains albumin in a large quantity. The sediment after a
few hours shows hyaline casts and octahedral crystals of calcium oxalate
under the microscope. Great prostration occurs with cold, clammy sweats,
a feeling of numbness of the limbs, feeble, irregular and rapid pulse, and
shallow, gasping, hurried respirations. The condition of collapse passes into
coma, which ultimately ends in death. Sometmes, cramps, convulsions,
lockjaw and delirium precede death.
Fig. 165.—Stomach in poisoning by Oxalic Acid.
(From Pathology Museum, Grant Medical College, Bombay.)
In his treatise on Poisons Christison has remarked: " If a person
immediately after swallowing a solution of a crystalline safe, which tasted
purely and strongly acid is attacked with burning in the tfefgat, then with
burning in the stomach, vomiting, particularly of bloody Matter, imper-
ceptible pulse and excessive languor, and dies in half an hour, or still more
in twenty, fifteen or ten minutes, I do not know any fallacy which can
interfere with the conclusion that oxalic acid was the cause of death. No
parallel disease begins so abruptly and terminates so soon; and no other
crystalline poison has the same effect."