Aqua Fortis, the nitrous acid of a certain strength, and so called from its dissolving power; but, when in a concentrated and smoking state, it is denominated spirit of nitre. It is made by distilling equal parts of crude nitre with calcined vitriol; or by carefully mixing one part of oil of vitriol with nine of pure spirit of nitre.—See Acids.

As this powerful liquid is used for various purposes in the arts and manufactures, but chiefly by dyers, brass-founders, hatters, etc. great caution should be observed, both in preparing and employing it, because it possesses a very caustic property, and its fumes are highly deleterious to the organs of respiration. Hence those artisans frequently become subject to convulsive coughing and blood spitting, paralytic affections, trembling, paleness of countenance, loose teeth, the loss of smell and taste, and at length, pulmonary consumption. In order to prevent these fatal effects, we seriously advise them to make use of oily and bland nourishment, and externally to secure the mouth and nose, by tying a handkerchief round those parts, while they are exposed to the fumes of this volatile acid.

But in casualties where a person has, by mistake, swallowed a portion of aqua-fortis, the following treatment will be the most proper for averting the imminent danger of suffocation. Immediately after the accident, luke-warm water ought to be drunk in the greatest possible quantity, even to the amount of several gallons, to weaken the causticity of the poison. Next, a solution of half an ounce of salt of tartar, or clean pearl-ashes, in one pint of water, should be taken in about six or eight small draughts; and as the effervescence thus occasioned in the stomach, greatly tends to weaken that organ, it will be necessary to make use of more water, and other diluent, oily, or mucilaginous drinks.

We are of opinion, that a solution of borax, or tincal, in the proportion of three drams to a pint of water, forms a more effectual anti-dote than the vegetable alkali; because the former, by uniting with acids, causes no effervescence.—• There are instances of persons having completely obviated the ill effects of this poison, simply by drinking small portions of sweet oil, frequently repeated, for three days successively.

If, however, the sensation of a burning pain in the stomach and bowels should not subside, after plentiful vomiting, large draughts of sweet cow's milk must be swallowed, with the addition of one dram, or sixty drops of liquid tartar, usually called oil of tartar, to each pint. But previously to the expulsion of the poison by vomiting, or the neutralizing of it with alkaline solutions, neither milk, oily, nor saponaceous draughts can be taken with advantage. Hence these ought to conclude the cure;' during which the patient may fre-quently use gargarisms and clysters of the same liquids, which are directed to be taken internally. In deed, after the poisonous fluid has left the stomach, and entered the intestinal canal, the principal benefit will be derived from emollient and balsamic injections.