The Alkaline Principle of A. Belladonna.
Preparation. — The following is the process employed by Mein. The roots of plants two or three years old were selected. Of these, reduced to an extremely fine powder, 24 parts were digested, for several days, with 60 parts of alcohol of 86 or 90 per cent. The liquid having been separated by strong expression, the residue was treated anew with an equal quantity of alcohol ; and the tinctures, poured together and filtered, were mixed with one part of hydrate of lime, and frequently shaken for twenty-four hours. The copious precipitate which now formed was separated by filtering; and diluted sulphuric acid was added drop by drop to the filtered liquor, till slightly in excess. The sulphate of lime having been separated by a new filtration, the alcoholic liquid was distilled to one-half, then mixed with six or eight parts of pure water, and evaporated with a gentle heat till the whole of the alcohol was driven off. The residual liquid was filtered, cautiously evaporated to one-third, and allowed to cool. A concentrated aqueous solution of carbonate of potassa was then gradually added, so long as the liquid continued to be rendered turbid ; and the mixture was afterward suffered to rest some hours. A yellowish resinous substance which opposes the crystallization of the atropia was thus precipitated. From this the liquid was carefully decanted, and a small additional quantity of the solution of the carbonate was dropped into it, till it no longer became turbid. A gelatinous mass now gradually formed, which, at the end of twelve or twenty-four hours, was agitated in order to separate the mother-waters, then thrown upon a filter, and dried by folds of unsized paper. The substance thus obtained, which was atropia in an impure state, was dissolved in five times its weight of alcohol ; and the solution, having been filtered, was mixed with six or eight times its bulk of water. The liquor soon became milky, or was rendered so by evaporating the excess of alcohol, and, in the course of twelve or twenty-four hours, deposited the atropia in the form of light yellow crystals, which were rendered entirely pure and colorless by washing with a few drops of water, drying on blotting paper, and again treating with alcohol as before. From twelve ounces of the root, Mein obtained by this process twenty grains of the pure alkali. — Jour. de Pharm. xx, 87.
History. — Thus prepared, atropia crystallizes in white silky prisms, is inodorous, and of a bitter taste ; dissolves in ether or absolute alcohol, and slightly in water; it melts above 212°, and forms soluble salts with sulphuric, nitric, muriatic, and acetic acids. At an ordinary temperature, water dissolves about 1/500th, but aided by heat a much larger portion is taken up; the solution has a bitter, disagreeable taste. Dr. A. von Planta found atropia prepared by Merck to possess the following properties: It dissolved in 299 parts of water at the ordinary temperature ; alcohol dissolved it in almost every proportion, ether less readily. Its solubility in all these fluids was increased by heat. At 194° F. it fused to a clear transparent mass,, which became brittle on cooling ; on the reapplication of heat, and again allowing it to cool, it was converted into stellate groups of crystals. At 284° F. the greater portion is destroyed. Heated upon platinum foil, it melts, puffs up, gives off white fumes, and burns with a bright flame, leaving a shining black cinder, which finally disappears entirely. It has a strong alkaline reaction, and combines with acids forming uncrystallizable salts, soluble in water and alcohol, but sparingly so in ether. Its formula is C34 H25 N O6 = 289.
Properties and Uses. — Same as Belladonna. Internally from one-twentieth to one-tenth of a grain may be given ; and for external use it is preferred on account of its quicker action, more uniform strength, and greater cleanliness. One grain dissolved in four fluidrachms of distilled water by means of a few drops of acetic acid, will, on the application of one drop of this solution to the inner surface of the lower lid, cause dilatation of the pupil in fifteen or twenty minutes. In neuralgia, one grain may be mixed with a drachm of lard, and rubbed on the affected part. Dr. Lusanna has used it successfully in this affection by the endermic and iatraleptic method. The skin being previously removed by a blister, or, what is still better, because more speedy, the ammoniacal pomade of Goudret, when the atropia is dissolved in a small quantity of alcohol, then mixed with simple ointment and applied to the denuded surface. In this way, a half grain to a grain may be employed in the twenty-four or forty-eight hours. Iatraleptically, he uses the following ointment in the form of frictions over the part affected every two or three hours, consuming a portion the size of a pea each time : Rx. Atropia, 5 centigrammes, Alcohol at 36, q. s. Dissolve. Add axungia, 12 grammes.