as a thinker and politician, vagueness and want of practical determination. His historical and philosophical works, though showing much reading, fertile thought, abundant facility of expression, and occasionally, where prejudice does not come in, acute judgment, are rather (as not a few of them were in fact) reported lectures than formal treatises. His rhetorical power was altogether superior to his logical power, and the natural consequence is that his work is full of contradictions. These contradictions were, moreover, due, not merely to an incapacity or an unwillingness to argue strictly, but also to the presence in his mind of a large number of inconsistent tastes and prejudices which he either could not or would not co-ordinate into an intelligible creed. Thus he has the strongest attraction for the picturesque side of medieval ism and catholicity, the strongest repulsion for the restrictions which medieval and Catholic institutions imposed on individual liberty. He refused to submit himself to any form of positive orthodoxy, yet when a man like Strauss pushed unorthodoxy to its extreme limits Quinet revolted. As a politician he acted with the extreme radicals, yet universal suffrage disgusted him as unreasonable in its principle and dangerous in its results. His pervading characteristic, therefore, is that of an eloquent vagueness, very stimulating and touching at times, but as deficient in coercive force of matter as it is in lasting precision and elegance of form. He is less inaccurate in fact than Michelet, but he is also much less absorbed by a single idea at a time, and the result is that he seldom attains to the vivid representation of which Michelet was a master.
Bibliography.—His numerous works appeared in a uniform edition of twenty-eight volumes (1877–79). His second wife, in 1870, published certain Mémoires d’exil, and Lettres d’exil followed in 1885. In that year Prof. George Saintsbury published a selection of the Lettres à sa mère with an introduction. For many years Quinet received little attention in France, but it was revived, though not very strongly, by the publication in 1899 of Madame Quinet's Cinquante ans d’amitié (that between her husband and Michelet), and by the centenary of his birth. On this latter (1903) appeared A l’occasion du centénaire, by E. Ledrain; see also Libres Penseurs réligieux, by E. Paris (1905). There is in English an elaborate Early Life and Writings of Edgar Quinet, by R. Heath (London, 1881). (G. Sa.)
QUININE, the most important alkaloid contained in cinchona bark (see Cinchona). In 1810 Gomez of Lisbon obtained a mixture of alkaloids which he named cinchonino, by treating an alcoholic extract of the bark with water and then adding a solution of caustic potash. In 1820 Pelletier and Caventou proved that the cinchonino of Gomez contained two alkaloids, which they named quinine and cinchonine. Later quinidine and cinchonidine were discovered, and subsequently several other alkaloids, but in smaller quantity.
Chemistry.—The alkaloids exist in the bark chiefly in combination with cinchotannic and quinic acids. The cinchotannic acid apparently becomes altered by atmospheric oxidation into a red-colouring matter, known as cinchono-fulvic or cinchona red, which is very abundant in some species, as in C. succirubra. For this reason those barks which, like C. Calisaya, C. officinalis, and C. Ledgeriana, contain but little colouring matter are preferred, the quinine being more easily extracted from them in a colourless form. The exact mode of extraction adopted by manufacturers is secret. That hitherto adopted by the Indian Government for the preparation of the cinchona febrifuge (see below) is simple, but the whole of the alkaloid present in the bark is not obtained by it. This method is to exhaust the powdered bark with water acidulated with hydrochloric acid and then to precipitate the alkaloids by caustic soda. Another method consists in mixing the powdered bark with milk of lime, drying the mass slowly with frequent stirring, exhausting the powder with boiling alcohol, removing the excess of alcohol by distillation, adding sufficient dilute sulphuric acid to dissolve the alkaloid and throw down colouring matter and traces of lime, &c., filtering, and allowing the neutralized liquid to deposit crystals. The sulphates of the alkaloids thus obtained are not equally soluble in water, and the quinine sulphate can be separated by fractional crystallization, being less soluble in water than the other sulphates.
Quinine of commerce is the neutral sulphate, C20H24N2O2·H2SO4·8H2O, which occurs in commerce in the form of very light slender white acicular crystals. It is soluble in about 780 parts of cold Water, but in 30 of boiling water, 60 of rectified spirit (sp. gr. 0.83), and 40 of glycerin. its solubility in water is lessened by sodium or magnesium sulphate, but is increased by potassium nitrate, ammonium chloride, and most acids. It is not soluble in fixed oils or in ether, although the pure alkaloid is soluble in both. It becomes phosphorescent on trituration. When prescribed it is generally rendered more soluble in water by the addition of dilute sulphuric acid or of citric acid, one drop of the former or § ths of a grain of the latter being used for each grain of the quinine sulphate. Quinine is precipitated from its solution by alkalis and their carbonates. It is, however, very soluble in excess of ammonia. The acid solution of sulphate of quinine is fluorescent, especially when dilute; and it is laevo-rotatory. When a solution of chlorine is first added and then ammonia an emerald green colour, due to the formation of thalleoquin, is developed. This test answers with a solution containing only 1 part of quinine in 5000, or in a solution containing not more than 120000 part if bromine be used instead of chlorine. The fluorescence is visible in an acid solution containing 1 part in 200,000 of water. By adding an alcoholic solution of iodine to a solution of the sulphate in acetic acid a compound known as herapathite, 4Qu·3H2SO4·2HI·I4·6H2O, is obtained, which possesses optical properties similar to those of tourmaline; it is soluble in 1000 parts of boiling water; and its sparing solubility in cold alcohol has been utilized for estimating quinine quantitatively. The other alkaloids are distinguished from quinine thus: quinidine resembles quinine, but is dextro-rotatory, and the iodide is very insoluble in water; the solution of cinchonidine, which is laevo-rotatory, does not give the thalleoquin test, nor fluorescence; cinchonine resembles cinchonidine in these respects, but is dextrorotatory.
Commercial sulphate of quinine frequently contains from 1 to 10%, of cinchonidine sulphate, owing to the use of barks containing it. The sulphate of cinchonidine is more soluble than that of quinine; and, when 1 part of quinine sulphate suspected to contain it is nearly dissolved in 24 parts of boiling water, the sulphate of quinine crystallizes out on cooling, and the cinchonidine is found in the clear mother liquor, from which it can be precipitated by a solution of potassium and sodium tartrate. Samples of quinine in which cinchonidine is present usually contain a smaller percentage of water than the pure sulphate. Traces of quinidine are also sometimes, though rarely, found in commercial quinine, but its presence iioes not detract in a medicinal point of view from the value of the after.
Owing to its voluminous character as much as 18 % of water may remain present in apparently dry samples of sulphate of quinine. If it loses more than 14.6% of water when dried at 100° C. it contains an excessive amount of moisture. Owing to its variability in this respect, and to its insolubility, certain other salts have largely replaced the sulphate in modern medicine.
Sulphate of quinine manufactured from cuprea bark (Remijia pedunculata) may contain from .10 to .90% of sulphate of homoquinine, which almost coincides in solubility with sulphate of quinine. Homoquinine is decomposed on treatment with caustic soda into quinine and a new alkaloid, cupreine, in the proportion of 2 to 3. Cupreine is soluble in a solution of caustic soda (differing in this respect from quinine), and therefore it is easy to prepare sulphate of quinine perfectly free from either homo quinine or cupreine. The medicinal properties of cupreine and homo quinine are of no practical importance.
In consequence of the high price of the alkaloid an attempt was made some years ago by the Government of India to manufacture from cinchona bark a cheap febrifuge which should represent the alkaloids contained in the bark and form a substitute for quinine. This mixture is known as cinchona febrifuge, and is prepared chiefly from C. succirubra, which succeeds better in India than the other species in cultivation, and grows at a lower elevation, being consequently procurable in large quantities at a comparatively low price. A mixture of the cinchona alkaloids, consisting principally of cinchonidine sulphate, with smaller quantities of the sulphates of quinine and cinchonine, is sold under the name of “quinetum” at a cheaper rate than quinine.
The chemical constitution of quinine and the allied alkaloids is not definitely settled, although certain relationships are well established. Thus quinine is methoxycinchonine or methylcupreine, cupreine being an oxycinchonine. These relations are shown by the formulae:—cinchonine = C19H21N2·OH; cupreine = C19H20N2(OH)2; quinine=C19H20N2(OH)(OCH3). Cinchonine yields on oxidation cinchoninic acid (γ-quinoline carboxylic acid). C9H6N·CO2H, whilst quinine gives quininic acid, C9H5(OCH3)(CO2H). This permits the writing of cinchonine, for example, as C9H6N·C10H15(OH)N, the hydroxy group being in the part ·C10H15(OH)N, about which the constitution is uncertain. The subject has been especially studied by Skraup, Konigs, and von Miller; Königs and von Miller have proposed formulae consisting of a piperidine ring substituted with a vinyl group; in the former that is a bridge of ·CH2·C(OH)· from the nitrogen atom to the γ-carbon atom, connexion with the quinoline residue being made at the
