Dr. Graves says, "In constipated habits I have occasionally derived very remarkable benefit from the use of nitric acid given in sufficient doses. It seems, like the carbonate of iron, to possess the advantage of combining tonic with aperient qualities" ("Clinical Medicine," ii., p. 215). I think that this different action of the medicine depends upon dose, and perhaps combination, and is not contradictory to that mentioned in the last section. Nitric acid in small or moderate doses is astringent, especially if prescribed with opium; but nitric acid in full doses has an aperient effect, especially in combination with bitter infusion, such as gentian; this may be traced either to direct intestinal irritation or to hepatic stimulation.

Otorrhoea occurring in scrofulous children or in syphilitic patients, is often quickly controlled by a course of this acid.

Purulent Ophthalmia, with extensive ulceration of the cornea, whether of a gonorrhoeal or scrofulous form, is much benefited by a course of 5 to 10 min. of the dilute acid three or four times a day, together with local treatment.