Mode of Operating

The first effect of the acid, given medicinally, is to stimulate the function of digestion. It probably enables the stomach to secrete the gastric juice more freely, upon the application of its proper stimulus, the food; and there is reason to think that it directly aids the solvent power of the juice itself, especially when, from a debilitated condition of the organ, that fluid may have been produced without the proportion of acid requisite for the due performance of this function. The phenomena which follow its more free exhibition are those purely of irritation of the mucous membrane, or of chemical corrosion. The astrin-gency which it often exhibits, in its action on the alimentary canal, probably results chiefly from its direct influence on the vital property of contractility in the tissues, or from a similar influence of the salts which it forms with salifiable bases, present in the contents of the stomach and bowels. It has long been noticed that this acid is peculiarly apt to give astringency to its salts, more so, indeed, than any other mineral acid, as evinced in the effects of alum and sulphate of iron. Perhaps another mode in which it proves astringent is by a chemical combination between the acid and the albuminous constituent of the superficial epithelial layers, causing a contraction of the tissue beneath. Something of this kind may occur when it is taken very largely; but, as ordinarily given for medical purposes, in small doses and very much diluted, it is extremely improbable that it produces any such effect. In the prefatory remarks on the mineral acids, I have expressed my opinion very decidedly that they never enter the circulation as such. In fact, should they be absorbed, they could exist there only an instant uncombined; for they would immediately be neutralized by the alkalies or albumen of the circulating fluid. Orfila injected a little diluted sulphuric acid into the veins of a dog, and caused its almost immediate death, with coagulation of the blood. But though, in the uncombined state, it cannot enter the circulation, it is undoubtedly, I think, often absorbed in the state of saline combination; and, as its salts prove astringent in the stomach and bowels, they may exercise a similar influence on the tissues generally, through the blood. Hence we may account for the supposed efficacy of the acid in the relief of hemorrhages, to the seat of which it can have no direct access. 13eing, how-ever, offensive to the system, when thus in excess in the blood, the salts are thrown off with the urine; and, in order that this elimination may be effected, it is probable that they have the property of stimulating the kidneys, and thus produce the diuresis, which has been noticed as an occasional result of the exhibition of sulphuric acid. It is not probable that the acid exerts any tonic influence on the tissues generally, other than the indirect promotion of sanguification and nutrition, by the in-vigoration of the digestive process. None of the salts of the acid, excepting those with a tonic base, as the sulphates of iron and zinc, act as tonics; and these metals produce their effects as well without as with the sulphuric acid. The absorption, therefore, of the salts it may form in the bowels, will not be followed by a tonic operation on the system. This is a point of more than merely speculative interest. If the opinion thus given be well founded, it would be useless to prescribe sulphuric acid with the view to a tonic effect, except in so far as it may be desirable to invigorate digestion.

Therapeutic Application

Sulphuric acid is admirably adapted by its local tonic powers to cases in which, without organic disease or vascular irritation of stomach, there is loss of appetite, with languid or inefficient digestion, general debility, and especially night-sweats. These conditions are often presented in the convalescence from acute diseases, particularly fevers, in which this acid, given alone, or in connection with the simple bitters, or some preparation of Peruvian bark, produces the happiest effects. The hectic fever of scrofula and consumption, and the advanced stage of suppurative inflammation, often afford similar indications.

In pure dyspepsia the medicine is little used; as, though it would seem to be indicated by the state of the digestive process, experience has not pronounced in its favour. To be curative in this affection, a remedy must be continued for a considerable time; and sulphuric acid, when its use is long persisted in, is apt to become irritant to the stomach, though well borne at first.

The acid has also been recommended as a tonic in low typhoid and malignant fevers; but I believe that it is of little advantage, and may often prove hurtful in these affections, by a too irritant action on the stomach, and through it indirectly on the system. It is only upon the alimentary canal, as before explained, that it acts directly as a tonic; and a mere gastric stimulant is not what is wanted in these cases.

With a view to its conjoint tonic and astringent effect, sulphuric acid has been employed in diarrhoea, cholera, hemorrhage, and colliquative sweats. In diarrhoea, connected with a relaxed state of the bowels, or in that complaint in its chronic form, and with a suspicion of ulceration of the mucous membrane, it has long been occasionally employed as an astringent or alterative; but it is only of late that it has been introduced, as the main remedial agent, into the treatment of acute diarrhoeas in their earlier stages, and of epidemic cholera. In the London Medical Times and Gazette for January, 1852 (page 31), is a communication from Dr. H. W. Fuller, of London, strongly recommending the use of the acid in this affection, and ascribing the first public notice of the remedy to a letter of Mr. Griffiths, which appeared In the Lancet three months previously. In a subsequent communication to the same journal (Oct. 1853, p. 344), Dr. Fuller reiterates his recommendation, based now upon a very large experience of the remedy. He had found it especially adapted to "acute autumnal" or epidemic diarrhoea, and to that form of the disease which precedes cholera; and in all such cases, amounting to upwards of ninety, it had proved invariably successful. In many of the cases there were cold extremities, severe cramps, vomiting and purging, and sometimes even rice-water discharges. He found it of little as bilious diarrhoeas, and certain chronic cases of the disease. In choleraic diarrhoea, and in cholera itself, in its earlier stages, no remedy is, he thinks, equally efficient. These statements have been confirmed by reports from other practitioners, which have appeared in the London journals; though, in the hands of some, the remedy has proved of no avail, and has occasionally seemed to be injurious. The mode of exhibiting the acid is to give from twenty to thirty minims of the diluted sulphuric acid of the Pharmacopoeias, with sufficient cold water to render it palatable, every hour until its beneficial effects are experienced. In some cases, Dr. Fuller recommends that the dose should be repeated every twenty minutes, or even more frequently, during the first hour. "Sometimes after the second dose," says Dr. Fuller, "more commonly after the third, and almost always after the fourth, the patient experiences a grateful sense of warmth at the epigastrium, heat returns to the extremities, the nausea and vomiting cease, the purging is stayed, the cramps subside, and the countenance reassumes its natural appearance." The patient goes on amending, and, after a few hours, the remedy may be suspended. If the acid be exhibited at intervals of six or eight, or even three or four hours, the same happy effects are not obtained. Should the liver not act properly after the cessation of the characteristic symptoms, a little blue mass may be exhibited. Some administer aromatic tinctures, opiates, or other adjuvants in conjunction with the acid; but Dr. Fuller prefers it simply diluted with water. In relation to the treatment of cholera itself, in its different stages, it would appear, from the statements in the return of the English Board of Health, that sulphuric acid can, at the best, boast of no superiority over other remedies. (B. and F. Medico-chirurg. Rev., July, 1855, Am. ed., p. 103).