Preparation. — Take of Aconite root, dried and bruised, two pounds; rectified spirit, three gallons ; diluted sulphuric acid, solution of ammonia, (Water of Ammonia, U. S.,) purified animal charcoal, each a sufficient quantity. Boil the aconite with a gallon of the spirit, for an hour, in a retort with a receiver fitted to it. Pour off the liquor, and again boil the residue with another gallon of the spirit and with the spirit recently distilled, and pour off the liquor also. Let the same be done a third time. Then press the aconite, and having mixed all the liquors and filtered them, distil the spirit. Evaporate the remainder to the proper consistence of an extract. Dissolve this in water and filter. Evaporate the solution with a gentle heat, so that it may thicken like syrup. To this add of diluted sulphuric acid, mixed with distilled water, sufficient to dissolve the aconitina. Next drop in solution of ammonia, and dissolve the precipitated Aconitina in diluted sulphuric acid, mixed, as before, with water. Then mix in the animal charcoal, occasionally shaking for a quarter of an hour. Lastly, filter, and having again dropped in solution of ammonia, so as to precipitate the aconitina, wash and dry it.
Chemical Properties. — Aconitina, when freshly precipitated, is said to be white, and in the form of a hydrate ; but it speedily parts with its water, and forms a brownish, brittle mass. It is thought not to be crystallizable. When obtained by evaporating its alcoholic solution, it is described as being in the form of a transparent, colorless mass, having a glassy luster. In powder, it is white, with a yellowish tinge. It is inodorous, and of a bitter and acrid taste, producing a benumbing impression on the tongue. It is unalterable in the air, and fusible by a gentle heat. It is sparingly soluble in water, requiring for solution 150 parts of cold, and 50 of boiling water ; alcohol or ether dissolves it readily. It neutralizes the acids ; but its salts are not crystallizable. That it contains nitrogen is proved by the evolution of ammonia, when it is decomposed by heat. It is incompatible with tinctures of iodine, and galls.
Properties and Uses. — Aconitina is too powerful a poison to be used as an internal medicine, yet as an external application, Dr. Turnbull has found it useful in gout, rheumatism, neuralgia, and diseases of the heart. He employed it in the form of tincture or ointment— one grain to one fluidrachm of alcohol, gradually increased to even eight grains; or two grains rubbed first with six drops of alcohol, and then with a drachm of lard, applied by friction three or four times a day ; and to be of service, it must produce a sensation of heat and prickling, followed by numbness and a feeling of constriction. It should not be applied to an abraded surface, or to a mucous membrane, lest it prove dangerous.