"Take of nitric acid, one fluid ounce; distilled water, nine fluid ounces. Mix."

Dublin.

"Take of nitric acid, three parts by measure, and of distilled water, four parts by measure. Mix, avoiding the noxious vapours. The specific gravity of this mixture is, to that of distilled water, as 1280 to 1000."

Acidum nitrosum dilutum, Edin. Diluted Nitrous Acid.

" Take of nitrous acid and of water equal weights. Mix, avoiding the noxious vapours."

These processes are intended for the more convenient apportionment of the dose in the exhibition of this acid.

When prepared according to the directions of the London College, f j. contains about grs. 72 of nitric acid, of 1.030 specific gravity, and 100 grains containing 14.3 grains of the concentrated acid, will saturate 31 grains of crystallized carbonate of soda; while the same measure of the same acid prepared after the Edinburgh and Dublin formulae, contains grs. 390.5 of the same acid; a difference which may lead to errors in practice; and is therefore to be regretted.

Medical properties and uses. - Nitric acid is tonic and antiseptic. When very largely diluted with water, it forms an agreeable and very useful beverage in fevers, particularly of the typhoid type. In larger doses, less diluted, it has been efficaciously administered in chronic hepatitis, even when dropsy has supervened; and has also been found serviceable in restraining violent sickness, in dyspepsia, asthma, and the majority of the cachexias From some observations of Dr. Scott, published at Bombay, in 1796, this acid excited considerable attention as a remedy for syphilis; but after the most ample trials, by almost every practitioner of any eminence in the country, its anti-syphilitic powers have not been found by any means to answer the accounts of them transmitted from India. The subsequent publications of Dr. Scott, however, have shown, that he did not employ nitric acid, but a mixture of three parts of hydrochloric acid, and two of nitric. It checks for a time the progress of the disease, but does not permanently remove the symptoms; and as Mr. Pearson justly remarks, "it would by no means be warrantable to substitute the nitrous (or nitric) acid in the place of mercury, for the cure of venereal1 complaints." It is, however, in many cases, of much benefit during a mercurial course, or prior to its commencement, when the constitution is impaired, and inadequate to support the effects of mercury; as by its tonic powers it promotes the general health, and lessens the action of the mercurial remedy on the mouth and fauces; yet, when it is pushed far, it affects the mouth and produces ptyalism.-When dropsy supervenes on reiterated courses of mercury, which is not unfrequent in broken-down constitutions, this-acid, Mr. Carmichael observes, given in as large doses as the stomach will permit, conjoined with digitalis, is productive of the utmost benefit.

We have found it of considerable service, given at the same time with mercury, in old obstinate ulcerations of the legs, although no venereal taint could be suspected; and it is employed with benefit as a local stimulant, in the form of lotion, in the proportion of f 3 ij. of the diluted acid, to Oj. of water, to fetid ulcers, attended with a thin ichorous discharge, and in caries of the bones. In India, and in this country, for some years past, nitric acid has been used, combined with hydrochloric acid, in the form of a bath3, and in this state it produces a slight excitement of the skin, a peculiar taste in the mouth, and, in other respects, nearly the same effect as when it is taken internally; but the chief perceptible effect of the mixed acid is on the bowels, which it keeps moderately open. Diluted nitric acid {Aquafortis) has often been employed as a poison. It is detected by the orange-coloured spots which are observed on the lips, chin, and hands of the patients; and, if death be the result, by the same colour being found in a large portion of the alimentary canal, the mucous membrane of which is converted into a fatty substance, and the stomach often perforated.

If any of the fluid can be obtained, the extrication of orange-coloured fumes on boiling it over copper filings, is a test of the presence of aquafortis. A good test also is a solution of indigo in sulphuric acid added to the suspected acid, until a perceptible blue is communicated. A drop of sulphuric acid is then to be added, and the mixture heated to ebullition. If the colour disappear, nitric acid is present. Soap and calcined magnesia, suspended in water, are the best antidotes.

The dose of the diluted acid is from x. to xxx. in f iij. of water, given three or four times a day. When used as a bath, the mixed acid should be added to the water, until it is about as sour as weak vinegar. Nitric acid, even when diluted, is incompatible in prescriptions with oxides, earths, alkalies, and the sulphurets, also the acetates of potassa and of lead. It decomposes the two last-named salts, and forms nitrates of lead and of potassa.

1 Pearson on Remedies for Lues Venerea, 188.

2 Blood drawn from the arm, after the daily use of this acid for some weeks, exhibits the buffy coat.

3 The proportions are two parts of hydrochloric acid and one of nitric, so diluted with water as to taste as sour as vinegar. Experience has not justified the high encomiums bestowed upon them.

Officinal preparations. - Bismuthi Trisnitras, L. Hydrargyri Acetas, D. E.