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Show Foe Pericane IGN So“te3":14 Y.. I Ss BS . ah RE a 120 COMMON PERUVIAN BARK TREE. T mayadd, that the tincture gives a black, while the cold infu. sion gives a green ; andthat, in all cases where an excess of the chalybeate is used, a green colour is produced. ‘These effects have been ascribed to the presence of tannin; but they have little resemblance to the intensity and durability of the blue co. lour producedin infusions of gall-nuts, and other powerful astring gents. They, however, show that the principle on which the colour depends is more soluble in alcohol and in boiling water, than in cold, and that it is very destructible. It was long be. lieved that cinchona was a powerful astringent ; but after Seguin’s discovery of gelatine as a test of the principle of astringency, Dr. Maton found that cinchona contained very little tannin. Ina my experiments, solution of gelatine did not affect the cold infusion, but precipitated the tincture, ‘diluted with waterand filtered, slightly, and the filtered decoction copiously. Theprecipitate in the last case was filamentous, and exactly re- sembled that produced withgelatine byinfusion of galls. Hence it appears that the tannin in cinchona is much less soluble in ale coho! and in cold water, than in hot. Dr. Maton discovered that infusion of cinchona was precipitated by infusion of nutgalls. Seguin, who afterwards made the same observat ion, concluded from it that cinchona contained gelatine, but erroneously, as I soon after proved, Infusion of galls is precipitated copi- ously, not only bythe filtered decoction of cinchona, but also by the infusion and tincture diluted and filtered ; and as these phenomena areinconsistent with the propertie s of gelatine or starch, (the only other principles which, so far as I know, precipitate infusion of galls,) I conceived myself authorized to ascribe them to a vegetable principle, not hitherto examined, soluble in alcohol andin water, and called it cinchonin. Seguin supposed that it was the tannin cf the infusion of galls which formed the precipitate in infusion of cinchona ; but this is extremely doubtful : for, as I have mentioned in another work, @ decoction of cinchona is precipitated both by gelatine and galls, and, when saturated by either of these re-agents, is still acted upon by the other; but an infusion of galls, after being saturated with gelatine » does not act on a decoction of cinchona. Now, if gelatine deprived the infusion of galls of no other principle but tannin, it would follow, that a decoction of cin- chona contains both tannin and a prineiple precipitable by tan* | } nin, which can scarcely be the =| case; and inde ed we do not at ne SPA PRe. ; COMMON PERUVIAN BARK TREE, 121 present see any way of accounting for the facts, but by sup. posing that the galls and cinchona contain each of them tannin, and another principle, of a different nature in each, not precis pitable by tannin, but by each other. It is satisfactory tofind that great master of analysis, Vauques lin, drawing nearly the same conclusion from his observations :— It would seem that it is to the tannin of the oak bark and galls that this principle (cinchonin) unites to form the precipitates observed in the infusions of these substances; but as this principle exists in some species which at the same time precipitate glue, it is doubtful that it really unites to the tannin ofthe oak bark, or that the prineiple in the other species of cinchona which precipitate glue, is actually tannin. But the one or the other of these suppositions must be correct, as the infusions of the two species precipitate each other. Dr. Irving obtained from cinchona a small portionof volatile oil, on which its aroma depends ; and Fourcroy and other chemists have observed, that during the evaporation of an infusion or decoction of cinchena, exposed to the air, an insoluble pellicle is formed on the surface. Fabbroni observed, that cinchonaloses its solubility by long exposure to the air, and even bybeing reduced to very fine powder; 100 parts of cinchona, when bruised, yielding from 12 to 16 of extract, and when finely powdered only 6 or 7; and that cinchona destroys the emetic property of tartrate of antimony, without losing its febrifuge virtues. Howlittle the analysis has hitherto accounted for the virtues of cinchona, is evident from three of the latest writers referring its virtues to totally different principles: Deschamps to the cin. chonate of lime, two doses of which, of 36 grains each, accord. ing to him cure every intermittent; Westring to the tanning principle ; and Seguin, on the contrary, to the principle which precipitates tannin. MEDICAL USES, On dead animal matter cinchona acts as an antiseptic, and on the living bodyit acts moreover as a stimulant, tonic, and anti- spasmodic. The discovery of its medical virtues was, in all probability, the result of accident. In fact, according to some, the Peruvians learned its use by observing certain animals affected with intermittents instinctively led to it; or, according to others, a Peruvian having an ague, was cured by accidentally drinkin g of a pool which, from some trees having fallen into it, tasted of |