The strong Mineral Acids, including Nitric, Sulphuric, and Hydrochloric, are powerful escharotics, destroying the tissues with which they come in contact, and when swallowed, they act as corrosive poisons. When properly diluted, they may be given internally with safety and advantage, acting in the characters of refrigerants, antalkalines, astringents, and tonics. What their precise action on the animal economy is appears uncertain; their first operation when swallowed is evidently to correct any excess of alkalescence which may be present in the stomach, and probably in the case of Hydrochloric Acid, to assist the digestive process, as it is well known that healthy gastric juice contains a portion of this acid. That they combine with the bases in the stomach, and are then absorbed into the system, is most probable, as they have been detected in the form of salts in the blood and in the urine. When Sulphuric Acid is given to women who are suckling, it causes griping in the child, although the milk is not coagulated by its presence. Of late years it has been much given as an astringent in some forms of diarrhoea. If continued for a long period, it produces derangement of the digestive functions, and a cachectic state of the body. If the Nitric and Hydrochloric Acids, either singly or in combination with each other, be continued in the same manner, their ill effects are not so immediately evident; indeed, they appear to act as alteratives, particularly on the liver, the biliary secretion becoming improved and the digestive organs strengthened, at the same time that they cause a considerable amount of salivation. The Nitric and Nitro-Hydro-chloric Acids also are especially valuable as tonics and alteratives in Syphilitic Cachexia. If, however, they are continued for too long a period, they produce the same cachectic state of the system as the Sulphuric Acid described above. When the mineral acids are added to freshly-drawn blood, they have been shown by Mr. Stevens and other physiologists to render the circulating fluid thick, black, and tarry, and to produce certain changes on the blood-corpuscles; but it is not probable that the same changes take place in the blood when they are introduced into the stomach; for, as previously observed, it appears certain that the acids combine with the bases in that viscus, before being absorbed into the system; but the whole subject requires further investigation. The dilute mineral acids have been administered as lithontriptics; but when given by mouth for this purpose, they are less certain in their operation than the vegetable acids. As a direct solvent of calculus, Nitric Acid, largely diluted, has been injected into the bladder. As refrigerants, the mineral acids are objectionable on account of their injurious action on the teeth; and this is not removed even when the acid is largely diluted.

2882. Vegetable Acids, including Citric, Tartaric, and Acetic Acids, when given internally, and properly diluted, closely resemble in their action and properties, the dilute mineral acids, as mentioned in the last section. Their primary action is that of antalkalines, although in this respect they are less permanent in their effects than the mineral acids. As refrigerants in fever, &c, they are in some respects preferable to the mineral acids, being more agreeable to the palate, less injurious to the teeth, and less liable to cause digestive derangement. As an antiseptic in Scurvy, Citric Acid is peculiarly valuable. As a means of rendering alkaline urine acid, Dr. Bence Jones* states that this may easily be effected by any vegetable acid, as Tartaric, Citric, or Acetic; and they have this advantage over the mineral acids, that they are less liable to cause the deposition of Uric Acid in the urine. More recently, Dr. Owen Rees has pointed out that the best way of rendering acid urine alkaline, is to exhibit the salts of vegetable acids, as the Citrate of Soda or Potassa. "The acids are decomposed," he says, " in the organism, and appear in the urine in the form of a carbonate." When Acetic Acid is taken in large and oftenrepeated doses, it causes great digestive derangement, a depressed arterial action, wasting of the body, &c.

* On Gravel, Calculus, and Gout, p. S6.

Med. Gas., July 4, 1851.

2883. In Typhus Fever, the Mineral Acids have been recommended in all countries, from the days of Forestus, Sydenham, &c. The theory of their action is obscure; but, as Dr. Murchison observes, their beneficial effects are undoubted. Dr. Murchison* adds, that during the last few years he has used these acids in hundreds of cases, and he believes them superior to any other method of treatment, though far from ascribing to them the wonderful effects attributed to them by some writers. He states that he usually commences with the Hydrochloric (xx.) and Nitric Acids (x.) every three hours, each dose being diluted with the patient's drink. In the advanced stages of severe cases, when the "typhoid state " is well marked, he prefers dilute Sulphuric Acid (xv. - xx.) every three hours, with Ether and small doses of Quinine. (See QuiniAe Sulphas.) He states that he has often observed marked improvement follow the commencement of the acid treatment, at whatever stage of the fever it was prescribed, and although no wine or brandy was given with it. In Typhoid (Enteric) Fever, Dr. Murchison considers that no remedies are superior to the Mineral Acids, and that they are often of real service, though their powers have been over-rated. Here he prefers the Hydrochloric and Sulphuric Acids: xv. - xxx. of the Dilute Acid every three or four hours. With each dose he combines about half a grain of Quinine, believing it to be of great service, especially when the disease has anything of a remittent character.