Acidum Carbazoticum. Picric Acid. Indigo Bitter. C12H, (NO4)3O,HO. Is obtained by the action of Nitric Acid on Indigo, and some other organic substances. It occurs in the form of bright yellow, shining scales, of a very bitter taste. It is soluble in water, uniting with salifiable bases, and forming compound salts.

Med. Prop. and Action. This Acid and its salts (Carbazotates) are tonic and astringent; but, according to Dr. Moffatt (who has been the first to introduce them as therapeutic agents), they act in the latter character indirectly, i.e., they retain discharges by improving the general tone of the system. In doses of grs. v. - x. and xv. the Acid in the experiments of Prof. Rapp proved rapidly fatal to animals, convulsions and complete insensibility preceding death. One marked peculiarity attending the use of this Acid and its salts is the production of a more or less bright yellow tinge to the skin, eye, and other organs of the body. This phenomenon has been examined by Prof.

* Med. Facts and Obs., vol. vii. (P). Lancet, March 15, 1862.

J Dict. Pract. Med., vol. i p. 523. § Clin. Lect., vol. ii. p. 2.

Crace Calvert and Dr. Moffatt,* who draw the following conclusions: - 1. Under the use of the Acid and its salts patients become as yellow as if they had a severe attack of jaundice; not only the skin, but the conjunctiva becoming coloured. 2 The time necessary for this coloration varied from two to sixteen days, the average duration being seven days. 3. The quantity of Acid generally required to produce this coloration was about fifteen grains. 4. The coloration disappears in two or three days after the medicine has been discontinued. 5. The presence of this Acid could be detected in the urine during the whole period of coloration, but not otherwise. This coloration, according to Dr. Moffatt, may depend either upon a change in the colour of the serum of the blood, or upon some change produced in the biliary system. but he inclines to the former of these theories. For medicinal uses the salts are preferable to the Acid, and it is thought that in their action they approximate to Quinine.

The doge of Carbazotic Acid or of the Carbazotates of Ammonia, Iron, Zinc, or Nickel, is about one grain thrice daily.

718. Therapeutic Uses

In a case of Continued Fever complicated with sub-acute Peritonitis and Tympanitis, Dr. Moffatt prescribed the Acid in grain doses thrice daily; and the patient got well just as if Quinine had been administered. A case of Chronic Eczema recovered also under its use; but in a case of Anmia, and in another of Scarlatina Maligna, in which it was employed, it was productive of little or no advantage. Two cases of Cephalagia, treated with the Carbazotate of Iron (gr. j. twice daily), recovered under its use. In both these cases, Quinine with Conium had previously failed. Two cases of Diarrhoea, one supervening on continued Fever, and the other, a chronic case of eighteen months' standing, yielded to the Carbazotate of Ammonia, in grain doses thrice daily (Moffatt).