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quinine


Значение термина quinine в knolik


quinine - Quinine
quinine - Quinine and similar alkaloids present in cinchona barks, the four possessing remedial value are, stated in order of merit, quinidine, quinine, cin-chonidine, and cinchonine. Their relative and total proportions are each subject to great variations, in fact no two samples of the bark are alike. Until recently, quinine was the only member of the group admitted into use; but experiment has shown that cinchoni-dine and cinchonine are very little inferior to the former as a febrifuge, and it is probable that they will not be thrown away in future. Quinidine is in too small proportion to deserve special notice. Though it is impracticable to state the percentage of alkaloids, individually or collectively, in each species of bark, the latter are nevertheless distinguished by well-marked characteristics, a knowledge of which is essential for their most economical and suitable employment. Pale or crown bark is rich in crystallisable quinine, and is highly valued by the manufacturers of quinine sulphate in this country. Yellow bark is even more highly esteemed for this purpose. Red bark, on the other hand, while as rich as either of the others in total alkaloids, contains only little quinine, and that difficult of extraction. Moreover, this species is hardier, grows better, and yields about ⅓ more bark than officinal is, so that as a source of total alkaloids it is more deserving of attention than the other two, though inferior to them if they could be got to grow as luxuriantly. The red bark, too, is the most valuable for the preparation of tonic decoctions, tinctures, etc., largely used in Europe; and in consequence of this fact, its price in Western markets is but little, if at all, inferior to that of the kinds richer in quinine. The barks best adapted for quinine-making fetch the best prices in European markets, and will probably continue to do so. Bed bark will doubtless recede in price when production increases, as the demand for that kind is limited in Europe; it is, however, the only kind likely to be used in the east for the local manufacture of a febrifuge, as efficient as, while much cheaper than, sulphate of quinine. Two conditions bearing upon this part of the subject are: (1) That high temperature increases the cinchonidine at the expense of the quinine, so that barks grown at a low elevation (or even at a high elevation, if exposed to sunlight), will be richer in the former and poorer in the latter, while a low mean temperature, within certain limits, favours the production of quinine; (2) That deprivation of light, without impeding the access of air and sun-heat, materially increases the proportion of total alkaloids.

The manufacture of a cheap febrifuge has engaged the serious attention of the Indian government, resulting in two such products - Broughton's "amorphous quinine," and the febrifuge called "quinetum" by Dr. de Vrij.

The former is prepared in the following way: Strips of the bark are placed in a copper pan with sulphuric acid (1½ per cent, for trunk-bark, 1 per cent, or less for prunings, etc.), and a quantity of water from the fourth extraction (v. post); the whole is boiled for 1 hr., then subjected to a strong screw press, the liquid being caught in a wooden vat. The bark is reboiled with liquor from a third extraction, with an additional ½ per cent, of acid, for 1 hr., and is again squeezed. A third boiling is given in liquor from a fourth extraction, and, after squeezing the bark is finally boiled with fresh water, sun-dried, and used as fuel. The resulting concentrated decoction is evaporated to 1/6, and cooled; it is then decomposed by addition of milk of lime in slight excess, which precipitates the alkaloids, with formation of insoluble lime salts; after standing for a day, the precipitate is filtered off, squeezed, dried, and powdered. The powder is then placed in the apparatus shown in Fig.; ABCD is a sheet-iron cone traversed by an upright tube E, terminating above in 4 open arms, and supported below on a flat iron disc CD. A copper vessel F G fits closely to the lower end of the cone. The latter is suspended, and connected through the tube H, with a simple worm tub. The cone is packed with the precipitate up to E, the lid is put on, and alcohol is added slowly from above, till F G is about ⅓ full of the saturated spirit which is then carefully neutralised by dilute sulphuric acid. The cone is then connected with the condenser through H, and a fire is lighted below. The spirit boiling in F G rises in vapour through E, passes out at the openings, and condenses so as to form a liquid stratum above the precipitate. This is observed by the gauge BI; uncondensed vapour passes through H, and is caught. A small quantity of spirit, by constant circulation, extracts all the alkaloids without waste. The alkaloid in F G is neutralised with dilute acid every two days. When the precipitate no longer contains any alkaloid, F G is removed, and the alcohol is distilled off; the alkaloid is washed with water, while the alcohol is recovered with a maximum loss of 6 per cent. The alkaloid is treated suddenly with about 10 times its bulk of cold water, which separates the black resin present; the addition of a little dilute acidulated solution of sodic sulphide will remove any copper accidentally present. The alkaloid solution being still coloured, a small quantity is precipitated by dilute caustic soda, the colouring matters falling at the same time. The whole is then filtered through cloth; and the alkaloid is precipitated by caustic soda, filtered, pressed, dried, and powdered. Potash may replace soda, if more easily or cheaply procurable. This process was employed to produce 600 lb. of alkaloid in the Nilgiris; but the product was found to cost more than ordinary commercial quinine, assuming the value of dry trunk bark at 2s. a lb., and branch-bark at 6d. The yield of alkaloid is, however, naturally much greater.

The second method, adopted by Wood, in Sikkim, is much simpler: The dry bark is crushed into small pieces - not powdered - and is put into casks, where it is macerated in the cold with very dilute hydrochloric acid; the liquor is then run off into wooden vessels, and mixed with an excess of strong solution caustic soda; the precipitate formed is collected on calico filters, and well washed with water. The precipitate is then gently dried, and powdered, constituting the crude febrifuge which requires purifying. This is performed by dissolving the product in dilute sulphuric acid, and adding a small quantity of a solution of sulphur in caustic soda. After 24 hrs., the liquor is carefully filtered; the filtrate is mixed with caustic soda, and the resulting precipitate is collected on calico, washed with a little water, dried, and powdered; it is then ready for use.

The operation is conducted in casks, worked in sets of three. Each cask receives 1 maund (82 lb.) of dry bark, which will undergo four successive macerations of half a week's duration, the liquor being passed through the three casks in rotation. The liquor used for the 4th (last) maceration is acidulated water; when drawn off, it forms the liquor for the 3rd cask; thence it is conducted to the 2nd cask; and finally to the 1st cask, containing new bark, whence it is run off for precipitation. When starting anew, each cask will contain dry bark, so that the system of rotation is not brought into full operation till after the first fortnight. The liquor for precipitation is run into tubs; the others are drawn into buckets for transference to the respective casks. Acidulated water is made in a vat, by adding 1 gal. hydrochloric acid to 100 gal. water. The weight of acid used in the exhaustion is 6½ per cent, of the weight of dry bark. The caustic soda solution consists of l part of the alkali dissolved in 3 parts of water; it is stored in iron vessels. The quantity required for precipitation of the bark liquor is judged of by the curdy appearance assumed by the precipitate; every 100 lb. of dry bark consumes about 6½ lb. of the alkali.

Filtration of the precipitate is commenced on the following day, when the liquor is transferred to the calico strainers, previously wetted. The first portions that run through are returned, until the passing liquor has a bright ruby colour; it is then allowed to flow away by a drain. When all the liquor has drained off, water is passed through the precipitate, until it ceases to acquire a red tint. The alkaloids on the filter should then exhibit a uniform cream-colour. The precipitate is dried, reduced to fine powder, and stored in suitable bins.

During the drying of the precipitate, a slight reddish-brown colour is developed; this is removed by the following process of purification: 14 gal. of water are mixed with 2 pints of sulphuric acid, and 20 lb. of the dry powder; about ½ pint of solution of sulphur in caustic soda is stirred in, and the whole is left for 24 hours. It is then filtered through calico into a clean vessel, care being taken to get the liquor perfectly bright; about 6 gal. of water are used to wash the sediment left on the filter; the clear filtrate is thoroughly mixed with soda solution, to precipitate the alkaloids; the precipitate is collected on calico, washed with a small quantity of water, drained dried, and reduced to fine powder.

Wooden vessels are not so suitable for this operation as are those of enamelled iron, or earthenware.

The bark used is exclusively dry succirubra, and care is taken to mix the root-, stem-, and branch-barks together, as nearly as possible in the proportions in which they are yielded by the plantations. Green bark would not be available at all seasons; and it has been found that the trifling cost of drying the bark is more than repaid by the better product.

The purified febrifuge is a fine white powder, which, however, acquires a slight buff tint by keeping. It never agglutinates, and is freely soluble in weak acids, such as lemon-juice, etc. The cost price of this febrifuge is estimated at 1s. 9d. an oz.; it is as efficient as quinine at 9s. an oz.

Quinine. - The bark is powdered, and boiled several times with sulphuric, or hydrochloric acid; after each boiling it is carefully expressed, and afterwards the liquors are mixed together. The quinine, cinchonine, and some impurities are precipitated with carbonate of soda, and the precipitate is collected in a cloth, compressed, dried, and digested with alcohol. The solution is next treated with dilute sulphuric acid, in sufficient quantity to exactly saturate the alkaloids, after which the alcohol is removed by boiling. The liquid is now allowed to cool, when the quinine is deposited as sulphate in crystals. The cinchonine, which is more soluble remains in the mother-liquors. The crystals of sulphate of quinine are dissolved in alcohol, and the solution is decolorised by the addition of a little animal black; they are subsequently purified by recrystallisation. If the mother liquors still contain quinine, they are precipitated by carbonate of soda, and the precipitate is re-dissolved in sulphuric acid. The sulphate of quinine is separated by repeated crystallisations. Pure quinine may be prepared from the sulphate by precipitating it with a mineral alkali. (Spons' 'Encyclopaedia.')

Рядом со словом quinine в knolik


piperineВ начало
буква ""
буквосочетание ""		salicine

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