The formula assigned to emetine by Reich (1863) was C₂₀H₃₀N₂O, that given by Glénard (1875) C₁₅H₂₂NO₂, and lastly that found in 1877 by Lefort and F. Würtz, C₂₈H₄₀N₂O₅.
The alkaloid may be obtained by drying the powdered bark of the root with a little milk of lime, and exhausting the mixture with boiling chloroform, petroleum-benzin or ether. It is a white powder turning brown on exposure to light and softening at 70° C. Emetine assumes an intense and permanent yellow colour with solution of chlorinated lime and a little acetic acid, as shown by Power (1877). A solution containing but ¹/₆₀₀₀ of emetine still displays that reaction. We found the alkaloid to be destitute of rotatory power, at least in the chloroform solution.
The above reactions may be easily shown thus:—Take 10 grains of powdered ipecacuanha, and mix them with 3 grains of quicklime and a few drops of water. Dry the mixture in the water bath and transfer it to a vial containing 2 fluid drachms of chloroform: agitate frequently, then filter into a capsule containing a minute quantity of acetic acid, and allow the chloroform to evaporate. Two drops of water now added will afford a nearly colourless solution of emetine, which, placed in a watch-glass, will readily give amorphous precipitates upon addition of a saturated solution of nitrate of potassium, or of tannic acid, or of a solution of mercuric iodide in iodide of potassium. To the nitrate Power’s test may be further applied.
If the wood separated as exactly as possible from the bark is used, and the experiment performed in the same way, the solution will reveal only traces of emetine. By addition of nitrate of potassium, no precipitate is then produced, but tannic acid or the potassico-mercuric iodate afford a slight turbidity. This experiment confirms the observation that the bark is the seat of the alkaloid, as might indeed be inferred from the fact that the wood is nearly tasteless.
Ipecacuanhic Acid, regarded by Pelletier as gallic acid, but recognised in 1850 as a peculiar substance by Willigk,[1388] is reddish-brown, amorphous, bitter, and very hygroscopic. It is related to caffetannic and kinic acids; Reich has shown it to be a glucoside.
Ipecacuanha contains also, according to Reich, small proportions of resin, fat, albumin, and fermentable and crystallizable sugar; also gum and a large quantity of pectin. The bark yielded about 30 per cent., and the wood more than 7 per cent. of starch.
Commerce—The imports of ipecacuanha into the United Kingdom in 1870 amounted to 62,952 lb., valued at £16,639.[1389]
Uses—Ipecacuanha is given as an emetic, but much more often in small doses as an expectorant and diaphoretic. In India it has proved of late a most important remedy for dysentery. Since the year 1858 when the administration of ipecacuanha in large (30 grains) doses began to be adopted, the mortality in the cases treated for this complaint has greatly diminished.[1390]
Adulteration and Substitutes—It can hardly be said that ipecacuanha as at present imported is ever adulterated. Although it may contain an undue proportion of the woody stems of the plant, it is not fraudulently admixed with other roots. But it very often arrives much deteriorated by damp: we have the authority of an experienced druggist for saying that at least three packages out of every four offered in the London drug sales, have either been damaged by sea-water or by damp during their transit to the coast.
Several roots have been described as False Ipecacuanha, but we know not one that would not be readily distinguished at first sight by any druggist of average knowledge and experience.