Pur. This may not be inferred from the form of its crystallisation, for the sulphates of quinidine and of cinchonidine may be obtained in the same form of crystallisation. As mentioned already, the reaction with chlorine and ammonia does not distinguish quinine from
quinidine, as both give the same green colour. “It is entirely soluble in water (hot), and more readily so when an acid is present. Precipitated by ammonia, the residuary liquid, after evaporation, should not taste of sugar. By a gentle heat it loses 8% or 10% of water. It is wholly consumed by heat. If chlorine be first added, and then ammonia, it becomes green.” (Ph. L. 1836.) “On adding chloride of barium to 100 gr. of this salt, dissolved in water mixed with hydrochloric acid, 26·6 gr. of sulphate of baryta, dried at a red heat, are prepared.” (Ph. L. 1851.) “A solution of 10 gr., in 1 fl. oz. of distilled water, and 2 or 3 drops of sulphuric acid, if decomposed by a solution of 1⁄2 oz. of carbonate of soda, in two waters, and heated until the precipitate shrinks and fuses, yields, on cooling, a solid mass, which, when dry, weighs 7·4 gr. and when reduced to powder, dissolves entirely in a solution of oxalic acid.” (Ph. E.)
Adult. Sulphate of quinine is said to be often adulterated with starch, magnesia, gum, sugar, cinchonine, quinidine, &c.; but, according to De Vrij, those with starch, magnesia, gum, and sugar, are very rare if ever they were really observed. Very frequent are those with the sulphates of the other cinchona-alkaloids, and these become even still more frequent, as very different kinds of bark are used for the manufacture of quinine. Salicin is, if ever, but very seldom used for adulteration of quinine. The best practical test for the purity of sulphate of quinine is the following:—A saturated solution of the salt is made at 60° Fahr., and one part of this solution is mixed with 2 or 3 minims of a concentrated solution of iodide of potassium, whilst another part is mixed with 2 or 3 minims of a concentrated solution of tartrate of potash and soda. If the sulphate of quinine is pure its solution will remain unaltered by both reagents, even after rubbing the sides of the test tube with a glass rod and standing many hours. But if it contains one or more of the other cinchona-alkaloids there will appear either precipitates or striæ on the glass where it has been rubbed by the glass rod. Iodide of potassium indicates particularly the presence of even traces of quinidine, but also of cinchonidine and cinchonine, provided their quantity be not too small. Tartrate of potash and soda indicate, under these circumstances, only the presence of cinchonidine. The first three remain undissolved when the salt is digested in spirit; the fourth is dissolved out by cold water; the fifth may be detected by its total insolubility in ether; or, by precipitating the quinine by solution of potassa, and dissolving the precipitate in boiling alcohol; cinchonine crystallises out as the solution cools, but the quinine remains in the mother liquor; and the last, by the greater solubility and sp. gr. of the salt, &c. If the sample disengages ammoniacal fumes when treated with liquor of potassa, it contains sal ammoniac. The presence of most foreign
organic substances is also shown by the sample being turned brown, and being soon charred when treated with a drop of concentrated sulphuric acid. If it turn red it contains salicin, a substance which is now frequently used to adulterate sulphate of quinine. The pure sulphate is not discoloured by this reagent.
Uses, &c. The sulphate is more extensively employed than any of the other salts of quinine, and, indeed, to almost the exclusion of them. It is the article intended to be used whenever ‘sulphate’ or ‘disulphate’ of quinine, or even ‘quinine,’ is ordered for medicinal purposes, unless the name is qualified by some other term. It is a most valuable stomachic, in doses of 1⁄4 to 1 gr.; as a tonic, 1 to 3 gr.; and as a febrifuge, 2 to 20 gr.
Quinine, Sulpho-tar′trate of. Syn. Quinæ Sulpho-tartras, L. Prep. From sulphate of quinine, 4 parts; tartaric acid, 5 parts; distilled water, 20 parts; mix, gently evaporate to dryness, and powder the residuum.
Quinine, Tan′nate of. Syn. Quinæ tannas, L. Prep. Dissolve sulphate of quinine in slightly acidulated water, and add a solution of tannic acid as long as a precipitate forms; wash this with a little cold water, and dry it. The Ph. Græca orders infusion of galls to be used as the precipitant. In intermittent neuralgia.
Quinine, Tar′trate of. Syn. Quinæ tartras, L. Prep. (P. Cod.) From tartaric acid and quinine, as the acetate.
Quinine, Vale′′rianate of. Syn. Quinæ valerianas (Ph. D.), L. Prep. 1. As the acetate or citrate.
2. (Ph. D.) Valerianate of soda, 124 gr., distilled water, 2 fl. oz.; dissolve; also dissolve hydrochlorate of quinine, 7 dr., in distilled water, 14 fl. oz.; next heat each solution to 120° (not higher), mix them, and set the vessel aside for 24 hours; lastly, press the mass of crystals thus obtained, and dry them, without the application of artificial heat.