§ 567. Separation of Saponin.—Saponin is separated from bread, flour, and similar substances by the process given at p. 153, “Foods.” The process essentially consists in extracting with hot spirit, allowing the saponin to separate as the spirit cools, collecting the precipitate on a filter, drying, dissolving in cold water, and precipitating with absolute alcohol. In operating on animal tissues, a more elaborate process is necessary. The author has successfully proceeded as follows:—The finely divided organ is digested in alcohol of 80 to 90 per cent. strength, and boiled for a quarter of an hour; the alcohol is filtered hot and allowed to cool, when a deposit forms, consisting of fatty matters, and containing any saponin present. The deposit is filtered off, dried, and treated with ether to remove fat. The insoluble saponin remaining is dissolved in the least possible quantity of water, and precipitated with absolute alcohol. It is also open to the analyst to purify it by precipitating with baryta water, the baryta compound being subsequently decomposed by carbon dioxide. Basic lead acetate may also be used as a precipitant, the lead compound being, as usual, decomposed by hydric sulphide; lastly, a watery solution may be shaken up with chloroform, which will extract saponin. By some one of these methods, selected according to the exigencies of the case, there will be no difficulty in separating the glucoside in a fairly pure state. The organ best to examine for saponin is the kidney. In one of my own experiments, in a cat poisoned with a subcutaneous dose of saponin (·2 grm.), evidence of the glucoside was obtained from the kidney alone. The time after death at which it is probable that saponin could be detected is unknown; it is a substance easily decomposed, and, therefore, success in separating it from highly putrid matters is not probable.
§ 568. Identification of Saponin.—An amorphous white powder, very soluble in water, insoluble in cold alcohol or ether, having glucosidal reactions, striking a red colour with sulphuric acid, imparting a soap-like condition to water, and poisonous to animals, is most probably a saponin.
DIVISION III.—CERTAIN POISONOUS ANHYDRIDES OF ORGANIC ACIDS.
I.—Santonin.
§ 569. Santonin (C15H18O3) is a neutral principle extracted from the unexpanded heads of various species of Artemisia (Nat. Ord. Compositæ). The seeds contain, according to Dragendorff, 2·03 to 2·13 per cent. of santonin, and about 2·25 per cent. of volatile oil, with 3 per cent. of fat and resin. Santonin forms brilliant, white, four-sided, flat prisms, in taste feebly bitter. The crystals become yellow through age and exposure to light; they melt at 169°, and are capable of being sublimed; they are scarcely soluble in cold water, but dissolve in 250 parts of boiling water, freely in alkaline water, in 3 parts of boiling alcohol, and in 42 parts of boiling ether. Santonin is the anhydride of santonic acid (C15H20O4). Santonin unites with alkalies to form santonates. Sodic santonate (C15H19NaO4 + 31⁄2H2O) is officinal on the Continent; it forms colourless rhombic crystals, soluble in 3 parts of cold water.
§ 570. Poisoning by Santonin.—Eighteen cases of poisoning, either by santonin or santonin-holding substances, which F. A. Falck has been able to collect, were nearly all occasioned by its use as a remedy for worms. A few were poisonings of children who had swallowed it by accident. With one exception those poisoned were children of from two to twelve years of age; in five the flower heads, and in thirteen santonin itself was taken. Of the eighteen cases, two only died (about 11 per cent.).
§ 571. Fatal Dose.—So small a number of children have died from santonin, that data are not present for fixing the minimum fatal dose. ·12 grm. of santonin killed a boy of five and a half years of age in fifteen hours; a girl, ten years old, died from a quantity of flower heads, equal to ·2 grm. of santonin. The maximum dose for children is from 65 to 194 mgrms. (1 to 3 grains), and twice the quantity for adults.
§ 572. Effects on Animals.—Experiments on animals with santonin have been numerous. It has first an exciting action on the centres of nerves from the second to the seventh pairs, and then follows decrease of excitability. The medulla is later affected. There are tetanic convulsions, and death follows through asphyxia. Artificial respiration lessens the number and activity of the convulsions, and chloroform, chloral hydrate, or ether, also either prevent or shorten the attacks.