*(a) Nitrum Flammans, Volatile, Ammoniacale. This salt dissolves readily in water, and becomes pappy or fluid in a moist air: by flow evaporation in gentle warmth it shoots into large crystals, much resembling those of common nitre. It dissolves in six times its weight or less, ofrectified spirit of wine. In a beat equal to that of boiling water, it melts and looks like oil, without suffer-ing any loss of its substance; on increasing the heat a very little beyond that degree, it begins to exhale, and in a little time is wholly dissipated: the fumes, caught in proper ves-sels, condense not into a concrete salt, but a fluid spirit; in which, however perfect the neutralization was at first, the acid appears now to prevail. ' The salt thrown into a red-hot crucible, without addition of any inflammable matter, emits bright flames, without detonation or noise: the flashes continue to play on the surface till the whole quantity of the salt is dissipated.

This salt is in taste similar to common nitre, but some-what sharper or more penetrating. Taken in doses of from ten to twenty-five grains, it sensibly promotes urine; and if the patient is kept warm, perspiration or sweat: It is recommended by Kurella, preferably to the other neutral saline medicines, in inflammatory cases, in exanthematous fevers, and as an attenuant and resolvent in obstructions of the viscera. He gives it either in powder, mixed with absorbents neutralized by lemon juice, or dissblved in well dulcified spirits of vitriol or nitre, in which last form he finds it in some cases to answer best: from fifteen to twenty-five drops of the saturated solution are given for a dose in any agreeable warm liquor. He recommends it likewise externally against inflammations, erysipelases, and gouty pains, dissolved in spirit of wine, either by itself, or with the addition of camphor and opium. M. S. of Dr. Lewis.

Nitrum Cubicum

Nitrum flammans, volatile, five ammoniacale.

The acid, in the most concentrated state in which is is commonly met with, saturates about five sixths its weight of vegetable fixt alkali (a).

Solutions of calcareous earths in this acid are in taste bitterish and very pungent. They are difficultly made to assume a crystalline appearance; and when evaporated and exsiccated by heat, the dry salt deliquiates again in the air. This salt has not hitherto been employed medicinally, nor is it as yet much known. It is a common ingredient in waters, which when its quantity is considerable, it renders hard and in-disposed to putrefy, apparently impeding putrefaction in a much greater degree than an equal quantity of sea salt. Alkaline salts, fixt or volatile, added to the solutions, precipitate the earthy basis; and uniting with the acid in its stead, compose therewith, according to the spe-cies of alkali employed, the common, cubical, or ammoniacal nitre mentioned in the preceding paragraph.

The nitrous spirit dissolves zinc, iron, copper, bismuth, lead, mercury, and silver, the most readily of all the acids: tin it dissolves imperfectly: regulus of antimony it only corrodes: see the respective metals.

The concentrated acid, combined with a due proportion of rectisied spirit of wine, loses its acidity; the coalition of the two producing a new compound, of a gratefully pungent taste and colour, and which is given from a few drops to a tea-spoonful or more as mildly aperient, diuretic, antiphlogistic, in some degree anodyne and antispasmodic. On mixing the two spirits together, a great heat, ebullition, and noxious red vapours arise: this conflict is less violent when, cautiously and by little and little, the acid spirit is added to the vinous, than when the vinous is added to the acid. It is prudent also to place the bottle containing the spirit of wine, in a vessel of cold water. One part of the strong acid spirit is commonly taken to three of the spirit of wine ‡, or half a pound to a quart†: the mixture, after standing for some time that the two liquors may in some degree unite, is set to distil with a gentle fire, by which the union is completed, and the very volatile dulcified spirit separated from the more fixt acid that remains undulcified. The disillation has been directed to be continued so long as the spirit that comes over raifes no effervescence with fixt alkaline salts; it may be regulated more com-modioufly by performing the process in a water bath‡, for all that rifes in this heat will be found to be a pure dulcified spirit.

(a) Homberg, Memoim V acad. roy. des cienc, de Paris, pour Pann. 1699.

Nitrum Calcareum Verum

A subtile ethereal fluid, similar in its general qualities to that described under the head of vitriolic acid, is obtainable with the nitrous in a more compendious manner. If equal parts by measure of spirit of nitre and spirit of wine, of moderate strength, be mixed together, the bottle closely stopt, and set in a cool place, a large proportion of ether rises to the surface in a few days: it may be purified from the adhering acid, by making it with water in which some fixt alkaline salt has been dissolved, and then drawing off the ether by disillation. The medicinal qualities of this subtile fluid are not as yet much known.

Spiritusasthe-ris nitrosi † Ph. Lond. Acidum, nitri vinofum vul-go spiritus nitri dulcis ‡ Pb Ed,

Nitrous ether.