2. Quinine, Sulphate of. (C20H24N2O2)2.2H2SO4.7Aq. Syn. Normal sulphate of quinine, Disulphate of q., Quinine; Quinæ disulphas (Ph. L.), Quinæ sulphas (Ph. E., D., & U. S., & P. Cod.), Quinæ sulphas (B. P.), L.; Sulphate de quinine, Fr. Prep. 1. (Ph. L. 1836.) Take of yellow cinchona bark, bruised, 7 lbs.; sulphuric acid, 41⁄4 oz.; (diluted with) water, 6 galls.; boil them for 1 hour, and strain; repeat this a second time for 1 hour, with a like quantity of acid and water, and again strain; next boil the bark for 3 hours, in water, 8 galls., and strain; wash the residue with fresh quantities of boiling distilled water; to the mixed decoctions and washings, add moist hydrated oxide of lead to saturation, decant the supernatant fluid, and wash the sediment with distilled water; boil down the liquor for 15 minutes, and strain, then precipitate the quina with liquor of ammonia and wash the precipitate (with very cold water) until nothing alkaline is perceptible; saturate what remains with sulphuric acid, 1⁄2 oz., diluted with water, q. s., digest with animal charcoal, 2 oz., and strain; lastly, the charcoal being well washed, evaporate the mixed liquors, that crystals may form.
2. (Ph. E.) This process varies from the last one, in the bark (1 lb.) being first boiled in water (4 pints) along with carbonate of soda (4 oz.); the residuum, being pressed, is moistened with water, and again pressed, and this operation is repeated a second and a third time, the object being to remove, as much as possible, the acids, colouring matter, gum, and extractive, before proceeding to extract the alkaloid. Carbonate of soda is also used as the precipitant, instead of ammonia, and the precipitate is formed into a sulphate (disulphate) by being stirred with boiling water, 1 pint, to which sulphuric acid, 1 fl. scruple, or q. s., is subsequently added. The crystals, after digestion with prepared animal charcoal, 2 dr.,
are ordered to be dried at a heat not higher than 140° Fahr.
3. (Ph. D.) Yellow bark, 1 lb., is macerated for 24 hours in water, 2 quarts, acidulated with oil of vitriol, 2 fl. dr., and then boiled for half an hour, after which the fluid is decanted; this is repeated a second and a third time with water, 2 quarts, and oil of vitriol, 1 fl. dr.; the decanted (or strained) liquors are evaporated to a quart, and filtered, and slaked lime, 1 oz., or q. s., added to the solution until it exhibits a decidedly alkaline reaction; the precipitate is next collected on a calico filter, and, after having been washed with cold water, partially dried on porous bricks, and subjected to powerful pressure enveloped in blotting paper, is boiled for 20 minutes in rectified spirit, 1 pint, and the liquid, after subsidence, decanted; this is repeated a second and a third time with a fresh pint of spirit, and the residuum being well pressed, the mixed liquors are filtered, and the spirit removed by distillation; the brown viscid residuum is dissolved in boiling water, 16 fl. oz., boiled, and dilute sulphuric acid, 1⁄2 fl. oz, or q. s., added to render the solution neutral or only slightly acid; animal charcoal, 1⁄2 oz., is next stirred in, the mixture boiled for about 5 minutes, filtered, and set aside to crystallise; the crystals are dried on blotting paper by mere exposure to a dry atmosphere.
4. (B. P.) Yellow cinchona bark, in coarse powder, 16; hydrochloric acid, 3; distilled water, a sufficiency; solution of soda, 80; dilute sulphuric acid, a sufficiency. Dilute the hydrochloric acid with 10 pints of the water. Place the bark in a porcelain basin, and add to it as much of the diluted hydrochloric acid as will render it thoroughly moist. After maceration, with occasional stirring, for twenty-four hours, place the bark in a displacement apparatus, and percolate with the diluted hydrochloric acid until the solution which drops through is nearly destitute of bitter taste. Into this liquid (hydrochlorate of quinine) pour the solution of soda, agitate well, let the precipitate (quinine) completely subside, decant the supernatant fluid, collect the precipitate on a filter, and wash it with cold distilled water until the washings cease to have colour. Transfer the precipitate to a porcelain dish containing a pint of distilled water, and, applying to this the heat of a water bath, gradually add diluted sulphuric acid until very nearly the whole of the precipitate has been dissolved, and a neutral liquid has been obtained. (Or add about half the precipitated quinine to some water in an evaporating basin, warm the mixture and pour in diluted sulphuric acid until the precipitate has dissolved and the liquid is neutral or only faintly acid, then add the other half, stir well, and again heat liquid.) Filter the solution (sulphate of quinine), while hot, through paper, wash the filter with boiling distilled water, concentrate till a film forms on the surface of the
solution, and set it aside to crystallise. The crystals should be dried on filtering paper without the application of heat.
5. “Those who are well acquainted with the chemistry of the cinchona-alkaloids all agree with me in condemning the boiling of bark with dilute acids. I prefer the following method, which can also be used on a small scale for quinometry:—
“Yellow bark, or any other bark in which quinine prevails, like, for instance, that of Cinchona officinalis, 1 lb., is mixed with milk of lime, made from 4 oz. of lime and 40 oz. of water. After drying this mixture it is exhausted with strong methylated spirit (the strongest possible) and the slightly coloured solution neutralised with sulphuric acid, so that the liquor has a slight acid reaction upon blue litmus paper. After filtering or subsiding, the clear liquid is distilled and the residue in the still dissolved in water, carefully neutralised, so that the solution has a slight alkaline reaction upon red litmus paper, treated with charcoal and crystallised, &c.”—De Vrij.
6. (‘Hospital sulphate’—Mr E. Herring.) The crushed bark is boiled in a solution of caustic soda or potassa, to extract colouring matter and gum; it is then pressed, washed with cold water, a second time boiled with a solution of caustic alkali, and again pressed, washed, and pressed; the decoloured and purified bark is next exhausted by coction with acidulated water, in the usual way, and the filtered mixed decoctions are precipitated with carbonate of soda; the precipitated quina is then dissolved in hot dilute sulphuric acid, to saturation, when the ‘HOSPITAL SULPHATE’ crystallises out as the solution cools; this is, lastly, washed with a little cold water, drained, and dried.—The advantage of this process is the non-use of animal charcoal as a bleacher, and the consequent less cost of the product. In the preparation of his ‘WHITE SULPHATE,’ Mr Herring uses benzol as a solvent, instead of alcohol. Patent dated July 28th, 1853.
Prop. When pure, sulphate of quinine forms very light, delicate, flexible, white needles, which are efflorescent, inodorous, and intensely bitter; it is soluble in 740 parts of water at 60°, and in 30 parts at 212° Fahr.; it takes about 80 parts of cold rectified spirit for its solution, but is freely soluble in boiling alcohol and in acidulated water; it melts at 240° Fahr., and is charred and destroyed at a heat below that of redness. The crystals contain 76·1% of quinine, 8·7% of sulphuric acid, and 15·2% of water; of the last, they lose about 3-4ths by exposure to dry air, and nearly the whole when kept in a state of fusion for some time.