Infusum Armoraciæ Compositum. L. In this preparation the stimulant property of the horse-radish is materially aided by the mustard; pure alkalies, but not their carbonates, may form extemporaneous additions; for the other incompatibles, see Armoraciæ Radix. Dose, f℥iss. Form. 45.
Infusum Aurantii Compositum. L. A grateful stomachic, having the agreeable compound taste of its several ingredients; it has the merit of sitting easily on the stomach. Dose, f℥j-f℥iss.
Infusum Catechu Compositum. L.E. This infusion is a powerful astringent, rendered grateful by the addition of cinnamon; it will keep for several months, provided the directions of the Edinburgh College be not followed in adding the syrup. In prescribing it, we must remember that it contains a large proportion of tannin. See Catechu. Dose, f℥j-f℥iij.
Infusum Gentianæ Compositum. L. An elegant tonic and stomachic infusion. It affords a good example of the virtues of a natural substance being enhanced by the additions of art, as discussed at page 164, for the bitterness of the gentian is here subdued by the aromatic quality of the lemon and orange peel. Incompatibles. Acetate of lead throws down a copious precipitate from the infusion, and sulphate of iron strikes a brown colour, but no precipitate takes place for several hours.
Infusum Rosæ Compositum. L.E.D. This is an infusion of the petals of the red rose, rendered astringent and refrigerant,[[538]] by the addition of dilute sulphuric acid. By referring to the Dynameter, it will be seen that f℥j; does not contain more than four and a half minims of dilute acid, which are equivalent to three-sevenths of a minim of the strong concentrated acid. Wherever therefore we expect any advantage from this latter ingredient, the quantity must be increased by extemporaneous addition. Incompatibles. All those bodies which are decomposed by the sulphuric acid; the sulphates of iron and zinc do not immediately alter the infusion, but they slowly decompose it, producing precipitates of a dark colour. Dr. Clarke of Cambridge detected iron in the petals;[[539]] may not the presence of this metal enhance the tonic powers of the infusion? It affords a most elegant vehicle for the exhibition of cathartic salts.
Infusum Sennæ Compositum. L.E.D. A pint of water will take up the active matter of ℥j of senna, but nothing beyond that proportion; hence there is an unnecessary waste in the London process. The quantity of infusion directed to be made at one time, is also injudicious, since by simple exposure to the air for only a few hours, in consequence of the powerful affinity of its extractive matter for oxygen, a yellow precipitate takes place, and the infusion loses its purgative quality, and excites tormina in the bowels; in preparing it therefore, we see the necessity of conducting the process in covered vessels, and of making only such a portion as may be required for immediate use; indeed, notwithstanding every precaution, the extractive will to a certain extent become oxidized, and the infusion have a tendency to gripe.[[540]] Dr. Cullen used to say that Senna was one of the best purgatives, if it could only be divested of its griping quality; this however he was unable to obviate, because he was not aware of its cause, and therefore conjoined it with various aromatics, instead of those salts[[541]] which might be capable of increasing the solubility of its oxidized extractive, or the purgative activity of the infusion; see page 150, and 161. Soluble tartar and alkaline salts are its most useful adjuncts; it is however rarely prescribed in practice without the addition of other cathartics. (Form. 70, 76, 90.) Sydenham’s favourite “potio cathartica lenitiva,” consisted of an infusion of tamarinds, senna leaves, and rhubarb, with the addition of manna and syrup of roses. The addition of tamarinds renders the infusion more grateful but less active; when made with bohea tea, it is in a great degree deprived of its nauseous taste; a decoction of guaiacum increases its powers, and is said at the same time to render it milder. Bitters also very considerably exalt its efficacy, see page 153. A pint of the infusion with a drachm of jalap forms an excellent combination for a purgative enema. Incompatibles. The infusion is disturbed by strong acids; lime water; nitrate of silver; oxy-muriate of mercury; acetate of lead; tartarized antimony; and by an infusion of yellow cinchona. Dose, f℥j-f℥ij.
IPECACUANHÆ RADIX. L.E.D.
(Callicocca[[542]] Ipecacuanha.) Ipecacuanha.
Qualities. Form, tortuous pieces of the thickness of a goose-quill, surrounded by numerous prominent rings, separated by deep grooves. This root, when powdered, has a faint disagreeable odour, and a bitter sub-acrid taste. Chemical Composition. The late researches of M. M. Majendie and Pelletier have detected the existence of a new vegetable proximate principle in this root, to which ipecacuan is indebted for its emetic properties; they have, accordingly, denominated it Emetine.[[543]] It assumes the form of transparent brownish red scales, which are nearly inodorous, but have a slightly bitter, acrid, but not nauseous taste. Emetine is decomposed by a heat higher than that of boiling water; it is insoluble in water, in every proportion, without undergoing the least change; and in a moist atmosphere it deliquesces; it is also soluble in alcohol, but not in æther; nitric acid dissolves it, but at the same time decomposes it; dilute sulphuric acid has no action on it; muriatic acid and phosphoric acid dissolve it, without altering its nature; acetic acid dissolves it with great facility; corrosive sublimate precipitates it from its solutions, but tartarized antimony has no effect upon them; gallic acid, the infusion of galls, and acetate of lead, precipitate it. A grain excites violent vomiting, followed by sleep, and the patient awakes in perfect health! It exerts also a specific action on the lungs and mucous membrane of the intestinal canal; when taken in an overdose, its action can be instantly paralysed by a decoction of galls. There seems to be no great advantage in substituting this body for the ordinary powder of Ipecacuanha, except perhaps that its taste being much less offensive, it may very easily be given to children.[[544]] Emetine appears to exist in Ipecacuanha, combined in the following manner, emetine 16, oils 2, wax 6, gum 10, starch 40, woody fibre 20.
Since the discovery of Emetine, whose properties are described above, Pelletier has extended his researches into its composition and nature; and he has lately been enabled to state that this body, which in conjunction with Majendie, he had formerly announced as “a new vegetable proximate principle,” turns out to be a compound of a peculiar alkaline basis, which may be called Emeta, and some acid, together with an admixture of colouring matter; when compared with Emetine, it is what white crystallized sugar is to moist sugar. Its ultimate elements are oxygen, hydrogen and carbon; it is a white and friable substance, and unlike Emetin, is not altered by exposure to air; it is slightly bitter, and very sparingly soluble in water; with the mineral acids it forms salts, from whose solutions the infusion of galls throws down white and flocculent precipitates; the alcoholic solution of Emeta acts upon vegetable colour as an alkali.