Acidum Tannicum. Tannic Acid.

Botanical name: 

Related entry: Gallic acid.

Preparation: This acid is present in a majority of vegetable substances, and abounds in numerous barks and leaves–to all of which it imparts astringent properties. It is now mostly obtained by percolating ether through coarsely powdered nut-galls. The liquid that passes through separates into two parts, of which the lower stratum contains the tannic acid. The lower liquid is separated from the upper carefully, and evaporated in an air-pump over a surface of oil of vitriol. It forms a light, friable, slightly-yellowish powder; porous, of a pure astringent taste, and scarcely acid. It dissolves readily in water, and sparingly in alcohol.

This acid forms many peculiar compounds with both inorganic and organic substances, and is an article of much interest to the chemist. It rapidly precipitates gluten, albumen, and starch; and with gelatin forms an insoluble compound on which depends the successful manufacture of leather.

Properties and Uses: Tannin is a pure and very efficient astringent; and the rapidity with which it coagulates albumen and gelatin, makes it a valuable application in local hemorrhages. It may be used in powder or strong solution upon a bleeding surface; may be administered as an injection in hemorrhage of the uterus and bowels; and may be formed into an ointment for piles, and suppositories for piles and laxity of the lower bowel. It has, also been used in cases of heavy mucous discharges, as leucorrhea, gonorrhea, gleet, and catarrhs; but here it is only of temporary benefit, can not effect a cure, and should not be administered with a hope of securing more than a transient benefit. Like other active astringents, it should not be employed while inflammation or acute irritation is present. It has been well spoken of in sore nipples, as a gargle in sore-throat and salivation, and in colliquative sweats. It is rather agreeable to the stomach; but large doses leave the mucous surfaces harsh and dry, and inclined to persistent constipation. Two to five grains every three to six hours, is a usual dose; but ten and fifteen grains may be given in extreme cases. Prof. R.S. Newton is said to have used large doses successfully to check the profuse discharges in cholera, while bringing other appropriate medicines to bear. Five grains to a fluid ounce of water, form a good strength when used as a wash; but injections may be made weaker. In making an ointment, two scruples may first be rubbed with twenty minims of water, and this then worked up with an ounce of lard. Glycerin dissolves this acid readily; and a solution of it in glycerin will be found a good astringent and styptic application. Softened with glycerin, it is dipped in a mixture of two parts lard and one part white wax, to form suppositories. This article has been commended in the treatment of intermittents; and doses of ten or fifteen grains two hours before the cold stage, are reputed to be unfailing in breaking the chill. Of my own judgment, but not from experience, I should doubt this; nor do I think this a fitting agent for ordinary intermittents, though it may be of some service in those rare cases which are attended with considerable looseness of the bowels. A formula for using it with quinine will be found under Cinchona.

Styptic Colloid: Dr. B. W. Richardson, of England, has introduced to the profession a new preparation of tannin, under the above name. It is prepared as follows: A sufficient quantity of pure tannin is digested for several days in enough absolute alcohol to dissolve it perfectly. Then slowly add, with stirring, enough absolutely pure sulphuric ether to render the thick alcoholic solution quite fluid. Now add prepared gun cotton till it ceases to dissolve readily; and a little tincture of benzoin to give it an agreeable flavor. When this fluid is spread upon the surface, the alcohol and ether evaporate, and the other substances form a coating that adheres well, and also excludes the air. Few or many layers may be applied by a soft camel's-hair brush. It absorbs and congeals the flowing blood, and so makes an unirritating obstruction to any further escape from the blood vessels. It arrests hemorrhages very rapidly, whether from wounds or incisions, or after small or large surgical operations; from ulcerous surfaces, bleeding after extraction of teeth, etc. Cotton may be saturated with. it, and any bleeding cavity plugged with this. By absorbing the blood and excluding the atmosphere, it prevents decomposition and becomes antiseptic–qualities not possessed by any other styptic. It promises to prove a most valuable preparation, if one-fourth of the accounts in its favor are reliable. As a recent preparation, it is liable to exaggerated praise; but is easily made, and deserves a thorough trial.

The Physiomedical Dispensatory, 1869, was written by William Cook, M.D.
It was scanned by Paul Bergner at