The Carbonate, sometimes called the Subcarbonate of Potash. KO CO., + 2 HO. Comp. Potassa 57.6, Carbonic Acid 26.4, Water 16, in 100 parts.

Med. Prop. and Action. Antacid, alterative, and diuretic. Its action resembles that of Potash, but it is less caustic, and therefore can be administered in larger quantities. Milk is a good vehicle for its exhibition, as it disguises its taste. Its diuretic effect is greatly increased by the use of diluents, and by a combination with other diuretics. It passes through the kidneys unchanged. It is frequently used in the form of effervescing draughts, thus: - gr. xx. of the Carbonate saturates gr. xvij. of Citric Acid, or fl. drs. iv. of Lemon-juice. The salt requires to be kept in well-stoppered bottles, as it deliquesces on exposure to the air, The ill effects of its long-continued use, are the same as those of Liq. PotassAe (see that article).

Dose, gr. x. - xxx. freely diluted.

Incompatibles. Acids and Acidulous Salts; Tartar Emetic; Calomel; Corrosive Sublimate; Sulphates of Quinine, Iron, Zinc, and Magnesia; the salts of Lead and Silver.

2188. Therapeutic Uses

In Acidity of the PrimAe Via, Dr. Prout* employs a formula composed of gr. x. - 3ss. of the Carbonate, and gr. iv. - v. of the Nitrate of Potash in a draught. This he advises to be taken from three to six hours after a meal, when we suppose that the digestive process is about completed.

2189. In Calculous Affections, when the urine has an acid reaction, alkalies may be given with advantage. Soda was long employed in these cases, but Dr. Prout and other more recent authorities advocate the Carbonate of Potash, as the lithate of soda, which is formed when soda is exhibited, has been found occasionally to constitute a considerable portion of the urinary calculus. The intense pain attendant on the presence of a stone in the bladder, is often strikingly relieved by this and the other alkalies. It may be given in doses of gr. x. - gr. xxx. in mucilage, with fl. drm. j. - fl. drs. iss. of Tincture of Hyoscyamus. Like the Bicarbonate, it may be prescribed with advantage where there is an excess of Uric Acid in the urine.

2190. In Diseases of the Skin, the local application of alkaline lotions and ointments was first proposed by Devergie, and has been found very useful. In the chronic forms of Eczema, Herpes, and Pityriasis, Dr. Neligan§; advises an ointment composed of Carbonate of Potash j., and Lard 5ss. This is to be lightly smeared over the eruption, which should be also washed every morning with a weak solution of Potash (3ss., Water Oj.). When thick crusts exist, they should be first treated with emollient poultices, and the scabs removed. The ointment will then act more powerfully and readily. He directs soap and water never to be applied to the scalp in these affections. In various forms of Porrigo, Lichen, Acne, Impetigo, &c, a similar treatment has proved successful in the hands of Dr. Schedel.* In addition to the means proposed by Dr. Negligan, he speaks highly of the utility of local alkaline baths (Potas. Carb. ss - j. ad Aq. Oiv.).

* On Stomach and Renal Diseases, 4th Ed., p. 92. Op. cit.

See Ann. de Therapeutique, 1846. § Diseases of the Scalp, 8vo, 1848.