466 MEDICAL JURISPRUDENCE 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."