The dose of the officinal acid is from three to seven drops; but, as kept in the shops, it is often of less than the officinal strength; and no precise rule can be given under the circumstances. I have found, however, that the above quantity of the officinal acid makes a large wineglassful of water rather disagreeably sour: and enough, therefore, of any specimen employed should be added to water to produce this effect. In the uncertainty as to the strength of the acid, a small dose should be given at first, to be gradually increased until it produces some sensible effect upon the stomach, a little pain for example, and then to be somewhat diminished. The water may be sweetened, if so preferred by the patient. Special care should be taken to avoid injury to the teeth. (See Diluted Sulphuric Acid, page 364).

As a wash for ulcers, from twenty to forty minims of the strong acid may be added to a pint or a quart of water.

Incompatibles. The acid should not be administered with uncombined metals, alkalies, alkaline earths, or their carbonates, nor with soaps or sulphurets. Caution should always be observed not to drop it into a silver spoon, as it would thus form nitrate of silver, or lunar caustic. It should be administered from a glass or porcelain vessel.

Diluted Nitric Acid (Acidum Nitricum Dilutim. U.S., Br.) is an officinal preparation. The present Pharmacopoeia directs three troy-ounces of the officinal acid (sp.gr. 1.42) to be mixed with sufficient distilled water to make the Diluted Acid measure a pint; but, in order that the preparation may be of uniform strength, the apothecary, if unable to obtain a strong acid of the officinal specific gravity, should make the requisite allowance, and increase the proportion of the acid sufficiently to compensate for its feebleness. This he will be enabled to do by consulting the table of Dr. Ure (see U. S. Dispensatory), from which he can learn the quantity of strong acid in any specimen of a given specific gravity. The dose of the diluted acid is from twenty to forty drops. which should be taken in a large proportion of water. The preparation may be applied undiluted, by means of a camel's-hair pencil, to pseudomembranous exudations, and certain indolent and insusceptible ulcers; care being taken not to allow the application to extend beyond the surface affected.

* In reference to the surgical use of nitric acid, as an escharotic in piles and prolapsed rectum, see the Lond. Med. Timet and Gaz.. April, 1853, p. 343; Aug. 1864, p. 184; and Dec. 1855, p. 566.

An ointment of nitric acid was formerly officinal; but has been omitted in recent editions of the pharmacopoeias. It was made, according to the Dublin process, by melting together a pound of olive oil and four ounces of lard, and adding, upon the commencement of concretion, five and a half drachms of the acid. The resulting ointment, which was yellow and of a firm consistence, was used in cutaneous affections, more especially porrigo and impetigo.