Page:Treatise on poisons in relation to medical jurisprudence, physiology, and the practice of physic (IA treatiseonpoison00chriuoft).pdf/608

 to Murray, are convertible into each other,—the sweet variety becoming bitter by neglect,—the bitter becoming sweet by cultivation, or certain modes of management not well known,—and the seed of either variety producing plants of both. These statements as to the mutual convertibility of the two varieties require confirmation.

The bitter almond depends for its activity on the essential oil, which is common to all the vegetable poisons belonging to the present tribe. According to the researches of Robiquet and Boutron-Charlard, followed up by Liebig, the oil does not, like common essential oils, exist ready formed in the almond, but is only produced when the almond-pulp comes in contact with water. It cannot be separated by any process whatever from the almond without the co-operation of water,—neither, for example, by pressing out the fixed oil, nor by the action of ether, nor by the action of absolute alcohol. After the almond is exhausted by ether, the remaining pulp gives the essential oil as soon as it is moistened; but if it is also exhausted by alcohol, the essential oil is entirely lost. The reason is that alcohol dissolves out a peculiar crystalline principle, named amygdalin, which, with the co-operation of water, forms the essential oil by reacting on a variety of the albuminous principle in the almond, called emulsion or synoptase.

In some respects, therefore, the essential oil of almonds is quite peculiar in its nature, and quite different from the common essential or volatile oils.—The presence of hydrocyanic acid in it is easily proved by dissolving it with agitation in water, and treating the solution with caustic potass, followed by the mixed sulphates of iron and sulphuric acid.—The quantity of essential oil which may be procured from the bitter almond amounts, according to Krüger of Rostock, to four drachms from five pounds or a ninety-sixth part. The quantity of hydrocyanic acid in the oil varies considerably: Schrader got from an old sample 8·5 per cent., from a new sample 10·75; but Göppert got from another specimen so much as 14·33 per cent.

Effects on Animals.—The bitter almond is a powerful poison, which acts in the same way as hydrocyanic acid, but likewise excites at times vomiting and other signs of irritation. The first good experiments on it are those related in Wepfer's treatise on the Cicuta; but its properties seem to have been known even to Dioscorides. The symptoms it induces in animals are trembling, weakness, palsy, convulsions, often of the tetanic kind, and finally coma. But frequently it occasions vomiting before these symptoms begin, and the animal in that way may escape. According to Orfila, twenty almonds will kill a dog in six hours by the stomach if the gullet be tied; and six will kill it in four days when applied to a wound.