Synonym. Bismuthi Nitras. Lond. Bismuthi Subnitras. Dub.

Prep. Made by dissolving two ounces of bismuth (in coarse powder) in two fluid ounces and a half of nitric acid, diluted with three ounces of water, aiding the solution by heat; when the effervescence has ceased, decanting from impurities, evaporating the liquor to three fluid ounces, and pouring it into half a gallon of water, decanting the supernatant fluid from the precipitate which subsides, washing the sediment by agitation with water, and drying on a filter at a temperature of 212°.

The solution of bismuth in nitric acid, when poured into water, lets fall Nitrate of Bismuth, now called in the Pharmacopoeia, White Bismuth, formerly known as the tris-nitrate or sub-nitrate; the solution of Bismuth in nitric acid must, therefore, be considered as containing a ter-nitrate of the metal (Bi O3, 3 No3).

Prop. & Comp. A. heavy white powder sometimes pearly or crystalline. Composition (Bi O3, No5), but a little water is contained in it when prepared as above directed: its composition is also somewhat altered by washing. It is insoluble in water, and blackened by sulphuretted hydrogen; dissolves without effervescence in nitric acid, and the solution poured into water gives a white crystalline precipitate; dissolved in sulphuric acid, diluted with an equal bulk of water, it forms a solution which is blackened by sulphate of iron, showing the presence of nitric acid.

Off. Prep. Trochisci Bismuthi. Bismuth Lozenges. [Not officinal in U. S. P.] (White bismuth, fourteen hundred and forty grains; carbonate of magnesia four ounces; precipitated carbonate of lime, six ounces; refined sugar, thirty ounces; gum arabic, in powder, one ounce; distilled water, six fluid ounces; oil of cinnamon, half a fluid drachm, for 720 square lozenges.) Each lozenge contains two grains of white bismuth.

Therapeutics. It acts as a sedative to the stomach and intestines and is used with great effect in pyrosis, and some forms of vomiting; also to restrain diarrhoea, especially when phthisical in character: its remote effects are not well made out. Externally it is stated to allay irritation, and it has been used in some chronic skin diseases. It is also employed as a cosmetic.

Dose. 5 gr. to 20 gr. in powder; or suspended by means of mucilage of gum arabic or tragacanth. Of the lozenges, from 2 upwards.

Adulteration. Carbonate of lead, a dangerous addition, known by the tests given above; this salt effervesces with nitric acid, and the solution is precipitated by sulphuric acid. Arsenic has been occasionally found in the salt, detected by the sublimation of arsenious acid when the preparation is heated, and by the other tests given under that metal.

Carbonate of Bismuth (not officinal), [Bismuthi Sub-carbonas Sub-carbonate of Bismuth. U. S.], which occurs in the form of a fine white powder, is sometimes used in medicine for the same purposes as the nitrate of bismuth; it is supposed to be more soluble in the stomach than the nitrate, and on that account has been preferred by some; this advantage is at the best a doubtful one, and clinical experience as to the comparative value of the two preparations of bismuth is still wanting. The dose is the same as that of the Nitrate.