"Take of the dry, bruised roots of aconite, two pounds, rectified spirit, three gallons; diluted sulphuric acid, solution of ammonia, and purified animal charcoal, of each a sufficient quantity. Boil the aconite with one gallon of the spirit in a retort to which a receiver is fitted. Pour off the fluid; and again boil the residue with a fresh gallon of the spirit and what distilled over, and pour off the fluid. Let this be repeated a third time. Then express the aconite, and from the whole of the solutions, mixed and filtered, distil the spirit. Evaporate the residue to the thickness of an extract, which is to be dissolved in water and strained. Evaporate the solution with a gentle heat to the consistence of a syrup, and add to it as much sulphuric acid mixed with water as will dissolve the aconitina. Next drop in some solution of ammonia, and dissolve the precipitated aconitina with diluted sulphuric acid as before. Then add the animal charcoal, frequently agitating the mixture for a quarter of an hour; and finally, after again precipitating the aconitina by the solution of ammonia, wash and dry it."

The salt prepared by the foregoing process is one of that class of salts obtained from vegetable bodies, which the Continental chemists have termed alkaloids. I have already stated that it exists in Aconite; and the A. paniculatum is pointed out by the College of Physicians as that which should be employed to yield it; but every species of the genus possesses it in greater or less quantity. It exists in the roots of the plant in combination with an acid, which is still undetermined. The time to take up the roots is before the flower has seeded.

In order to procure the aconitina in granular crystals, it should be dissolved in alcohol, and left to spontaneous crystallization : but a large portion of it is uncrystallizable; there is consequently much waste in crystallizing it; but its purity is increased. It is said to be even in this state combined with another principle, named anemonin, from which it can be separated only "by repeated solution in and precipitation from acids." 1

Qualities. - Aconitina is procured in inodorous, granular, greyish white crystals, which have a bitter, somewhat acrid taste: they are soluble in 150 parts of water at 60° Fah., and in 50 parts at 212°. Both alcohol and aether readily dissolve them, and the solutions have an alkaline reaction. The crystals fuse in a moderate, and are decomposed in a strong heat; and when decomposing they yield ammonia. They form bitter uncrystallizable salts with diluted acids: the nitrate is colourless; the sulphate is yellow at first, and afterwards becomes of a deep violet hue.

1 Phillips, Trans. of the Pharm. p. 93.

Medicinal properties and uses. - Aconitina is the active principle of the aconite, and consequently operates on the animal economy in the same manner, but in a concentrated degree. It has been employed by one practitioner, Dr. Turnbull, in neuralgic affections, in doses of the sixteenth of a grain, made into a pill with any bland powder; but the remedial effects ascribed to it require to be confirmed. As an external application, it operates as a counter-irritant; but its action is accompanied with a sensation of cold, which is not easily explained. An embrocation may be prepared by dissolving grs. viij. of aconitina in f ij. of rectified spirit; or it may be used in the form of ointment, containing gr. j. of the alkaloid for each drachm of lard. It is preferable to render the aconitina more miscible with the lard by adding, previously to mixing the ointment, a few drops of alcohol to the aconitina.