Definition. - A dibasic organic acid, C2H1(OH)2(COOH)2, usually prepared from argol.

Description and Properties. - Colorless, translucent, monoclinic prisms, or crystalline crusts, or a white powder; odorless, having a purely acid taste, and permanent in air. Soluble in about 0.71 part of water and in 1.67 parts of alcohol; also in about 0.5 part of boiling water, and in 0.2 part of boiling alcohol.

Dose. - 10-30 grains (0.6-2.0 Gm.) [7 1/2 grains (0.5 Gm.), U. S. P.].

Antagonists and Incompatibles. - Alkalies are chemically incompatible with the vegetable acids. With the alkaline, earthy, and metallic bases vegetable acids unite to form salts, the acetates of which are all soluble.

Synergists. - Alkalies, and, under certain circumstances, mineral acids and the digestive ferments.

Physiological Action. - Externally and Locally. - The vegetable acids have about the same action externally and locally as the diluted mineral acids, not caustic but irritant, acetic acid being the most powerful and citric acid the weakest.

Internally. - Digestive System. - Their action on the salivary and gastric glands is similar to that of the mineral acids. Their influence upon the stomach is not so marked as that of hydrochloric acid, though the secretions from the intestinal glands are more augmented by vegetable than by mineral acids. Too large or continued doses of the vegetable acids produce flatulence and abdominal pain, and may even occasion diarrhea or enteritis.

Circulatory System. - Large doses retard and weaken the pulse. The oxidizable organic acids increase the alkalinity of the blood and of the urine, thus differing from the mineral acids.

Absorption and Elimination. - As stated, vetetable acids unite with the alkalies to form salts, as such entering the circulation. They are eliminated chiefly by the kidneys, increasing the excretion of both water and solids. Elimination also takes place to a considerable extent by the intestinal canal.

Poisoning. - Their toxic effects vary widely. Some are nontoxiccitric; tartaric is slightly toxic in very large doses; oxalic is a severe poison, the symptoms of which differ in many respects from those of poisoning by the mineral acids. The most important symptoms are: Either gastro-intestinal irritation with profound collapse or, at times, there is simple collapse with weak heart, stupor, unconsciousness, and death, due to central paralysis. Poisoning by potassium oxalate adds the effects of potassium, and there is more profound cardiac collapse.

Treatment of Poisoning. - Mild alkalies control the action of the milder organic acids. In oxalic-acid poisoning - suicidal, or poisoning by potassium oxalate, accidentally eating of "sour grass," rhubarb, rumex, or sorrel oxalis in any form - use gastric lavage, followed by magnesia or chalk, well diluted. Cardiac and respiratory stimulants are necessary. Small doses of opium and strychnine and atropine may be of service. Glacial acetic acid is a powerful corrosive acid.

Therapeutics. - Externally and Locally. - All the vegetable acids here described are irritant, more or less antiseptic, and hemostatic, acetic acid being the most powerful antiseptic of the three. Engle-mann regards acetic acid as superior to mercuric chloride as a disinfectant in obstetrical practice, employing a solution of from 3 to 5 per cent. for this purpose. A diluted solution is a valuable injection in gonorrhea of the female. Glacial acetic and trichloracetic acids are powerful caustics, and are much used to dissolve horny growths, warts, corns, etc.

The most important use of acetic acid is in the treatment of certain parasitic skin diseases, probably no remedy excelling it in cases of ringworm and pityriasis. Diluted acetic acid, or vinegar, is an efficient gargle in simple sore throat and the last stage of anginae of exanthemata, as well as a valuable hemostatic, especially in epistaxis.

Citric acid is but little used locally, although solutions have been employed with some success to relieve the itching and stinging of "prickly heat" and urticaria. A sponge-bath of lemon and water is a grateful and efficient means of reducing temperature and checking excessive sweating in disease.

Tartaric acid has been used by Potter as an application to the throat in diphtheria, the effect being to convert the membrane into a gelatinous mass, which is more easily expelled.

Internally. - Acetic acid is little used internally. Citric acid, however, in the form of a lemonade, is a refreshing refrigerant drink in fevers, while a similar hot lemonade taken at bedtime is a valuable and agreeable means of aborting a "cold." Lemon- or lime-juice is useful in scurvy, being unquestionably the most efficient remedy for the disease.

It is well known by the laity that eating lemons increases the functional activity of the liver. Lemons and citric acid, therefore, are efficient remedies in relieving attacks of biliousness and catarrhal jaundice, and they even appear to counteract the effects of malaria. Lemon-juice is an old and esteemed remedy in acute rheumatism. Citric acid is an invaluable adjunct in rendering the urine bland in gonorrheal or other forms of cystitis.

Vegetable acids are used for the same disorders of the digestive tract as mineral acids, although not so efficient as the latter, especially hydrochloric acid. Much of the benefit derived from sour table-wines is due to the fruit-acids they contain.

Contraindications. - Ordinarily the same as for mineral acids. It is a matter of observation that nursing mothers may produce a troublesome diarrhea in the infant by partaking too freely of vinegar or acid fruits.

Administration. - A solution of citric acid may be made of about the acidity of lemon-juice by dissolving 570 grains (36.93 Gm.) in 1 pint (473.17 Cc.) of distilled water. Vegetable acids when taken internally should be mixed with, or dissolved in, water and diluted and sweetened, that they may be pleasant to the taste and acceptable to the stomach.