This occurs native in the water near volcanoes, as in Java, and in the "Sour Springs," in the town of Byron, Genesee County, N. Y. It is found in combination in twenty-two natural sulphates, also with ammonium in rain-water, near towns. It contains 79 per cent. of anhydrous sulphuric acid, SO3.

There are two other forms of the same acid, the acidum sulphuricum dilutum, and the acidum sulphuricum aromaticum, which are weaker by one-seventh than the first-mentioned.


By passing sulphurous acid gas (sulphurous anhydride) into leaden chambers, and bringing it there into contact with steam and nitrous fumes (nitrous anhydride); from the latter it absorbs an atom of oxygen, becoming sulphuric acid (anhydrous), and this combines with water to form a dilute sulphuric acid, which is afterward concentrated up to a sp. gr. of 1.843; a small quantity of nitric oxide gas will act as a carrier of oxygen from the atmosphere to a large quantity of sulphurous acid. In chemical formulae the main reaction may be represented as follows:- SO2 + H1O + N2O3 = H1SO4 + 2NO.

Characters And Tests

The pure acid is an oily-looking, colorless liquid, but the commercial acid is often dark-colored from contained fragments of organic matter, which are charred by the acid. It has an energetic affinity for water, which it absorbs readily, so that a partially-filled bottle of acid, if exposed to the air, will, after a time, overflow; if quickly mixed with water it undergoes condensation, and much heat is evolved. A very small quantity of sulphuric acid, or of any soluble sulphate, can be detected by adding to the diluted solution a little chloride of barium, which gives a dense white precipitate, insoluble in acids.

Absorption And Elimination

Moderate doses of the dilute acid are readily absorbed, either as sulph-albuminates (Orfila), or, after combining with bases in the gastric secretion, as sulphate of potash or soda (Miguel): very small doses only in the latter form (Husemann).

The dilute acid forms with albumen both a soluble, and an insoluble compound according to the degree of dilution - the former resulting from quite weak acid (Berzelius). That dilute sulphuric acid may be absorbed through the skin, follows from the experiments of Lebkuchner, who induced acid reaction of urine and faeces by applications to the abdomen of rabbits.

Gubler teaches that this, like the other mineral acids, circulates in the blood, but loosely combined with albumen, and that on reaching the emunctories the combination breaks up, albumen remaining in the vessels, while the acid passes out with the excretions, combining with the bases therein found.

It has been a question whether after poisonous doses, the acid may be absorbed and remain free in the blood, leading to its coagulation. Geoghegan states that after 1 1/2 oz., when a woman survived thirty-one hours, he found traces of acid in the pericardium and in the kidney, not in the blood, but in that fluid he found much phosphoric acid, derived, he suggested, from phosphate of soda from which sulphuric acid had displaced it (Medical Gazette, xl.). In another case Dr. Walker found a trace in the cerebral fluid and in the cardiac blood (Edinburgh Journal, 1850). Casper found the blood and serous fluids acid, and Carus states that he found sulphuric acid in all the organs of a foetus, after a fatal dose taken by the mother ("Beck's Jurisprudence," ii., p. 429). More recent researches state that mineral acids cannot be detected free in the blood, and that its reaction cannot be rendered acid consistently with life (F. Walter; v. Hydrochloric Acid). It is not likely that the coagula described by Bouchardat in the great vessels were really due to direct action of free acid, - Taylor could find no trace of it in similar coagula ("On Poisons," p. 31).

The acid is eliminated by the urine, and according to Dr. Letheby, very quickly after full doses (Medical Gazette, xxxix., p. 116). Most observers agree that it cannot be found free in that secretion, but as sulphate (Bence Jones), and the heightened acidity is really due to uric and lactic acids displaced by the stronger sulphuric acid from their ordinary combinations. Seeing the comparatively small amount of sulphuric acid accounted for in the renal secretion, Headland suggested that some passed by the lower bowel and the skin, and this is probable.

Physiological Action (External)

The dilute acid, applied to the skin, causes some burning pain and pallor, followed by redness; more concentrated, it destroys the epithelium, changing it into a firm brown mass. It coagulates albumen, and disintegrates horny tissues with formation of leucin and tyrosin. In its full strength, it causes destruction and sloughing of any tissue by virtue of its strong affinity for organic bases, as well as for the water with which they are combined. The acid has disinfectant and antiseptic powers, and destroys infusorial life.

Physiological Action (Internal)