Pharmacologia / Fourth American, from the Seventh London Edition

by John Ayrton Paris

Gallate of Cinchonia, equally as insoluble as the Oxalate, whence the precipitate occasioned by pouring an infusion of galls into the decoctions of genuine cinchona.

Cinchonia, when heated, does not fuse before decomposition. Its ultimate elements are oxygen, hydrogen, and carbon; the latter being predominant.

The Kinic acid, which exists in native combination with the Cinchonia, amongst several other peculiar properties, is convertible by means of heat into a substance (acide pyrokinique,) which is crystallizable, and capable of producing with iron a most beautiful green colour.

2. Cinchona Cordifolia.

In the Yellow Bark, these chemists discovered also a salifiable base, quite distinct however in its character and habitudes from Cinchonia; they accordingly have designated it by another name, viz. Quinine, but which we shall hereafter call Quina. In speaking of these two bases, the authors compare them, in point of dissimilarity, to the fixed alkalies, potass and soda. Quina is distinguished from Cinchonia by the following characters. It cannot, like this latter body, be crystallized by evaporation from its alcoholic solution, although it may be obtained in transparent plates. It is very soluble in æther; in water it is as insoluble as cinchonia, but its taste is much more bitter. The salts which it forms are different from those of cinchonia, both in the proportion of their elements, and in the properties which they possess, being generally much more bitter. In comparing their composition, Quina will appear to have less capacity of saturation[^[464]] than cinchonia.

Sulphate of Quina. It forms crystals quite remarkable for their satin-like and pearly lustre. It is soluble in cold water, a property which is very considerably increased by an excess of acid.[^[465]] It appears from the observations of M. Callaude, apothecary at Annecy, that Sulphate of Quina exposed to a gentle heat, becomes highly luminous; and M. Pelletier has since found that Sulphate of Cinchonia, when exposed in a capsule to the steam of boiling water, exhibits the same phenomenon, but that neither Quina nor Cinchonia, by themselves, nor their acetates, possess this phosphorescent quality. This appears to be the most efficient of all the salts of Bark, and is the one from which I have frequently derived much advantage. In its exhibition we must be careful not to combine it with substances that form insoluble compounds with it. The Infusum Rosæ compositum is objectionable as a vehicle, on account of the astringent matter which it contains, and which therefore precipitates the Quina from its solution. I have lately seen a prescription, in which the salt is directed to be rubbed with a few grains of Cream of Tartar, and then to be dissolved in mint water. This is obviously injudicious, since Tartaric acid decomposes the sulphate, and occasions an insoluble Tartrate, which is precipitated. The form in which I have usually prescribed it is in that of solution, with a small quantity of sulphuric acid, in the proportion of a minim to every grain of the salt. A Wine of Quina may be made by adding five grains of the sulphate to a pint of Sherry; a Tincture, by dissolving the same quantity in eight fluid-ounces of Rectified Spirit. The sulphate is to be preferred to the pure Quina in these cases, because, when the tincture is made by using the alkali, not saturated by an acid, a precipitate is formed on adding it to aqueous liquors. Dose of the Sulphate, gr. i.–v.

Acetate of Quina, very remarkable for the great facility with which it crystallizes, and for the pearly aspect and agreeable stellated grouping of the crystals; whereas the acetate of cinchonia crystallizes with difficulty, and simply in plates transparent, and devoid of lustre.

Quina forms with the oxalic, gallic and tartaric acids, salts as insoluble as those which the same acids form with Cinchonia.

3. Cinchona Oblongifolia.

The Red Bark upon analysis was found to contain a double basis, and to yield both Cinchonia and Quina, and, what is still more extraordinary, the quantity of each exceeded that which is known to exist in the grey and yellow barks.