July i, 1884.] 



THE TROPICAL AGRICULTURIST 



13 



myself, for the purpose of testing the feasibility of ob- 

 taining aqueous extracts of cinchona better suited for use 

 in medicine than those which are at present official. 



I started with a decided opinion, founded on previous 

 observations, as to the direction in which the investigation 

 should be pursued, and the objects which it was most im- 

 portant to accomplish. They may be stated as follows : — 



1. That the red or succirubra bark is the sort most 

 suitable for uso in these operations. 



2. That the extracting liquid should be water, an aoid 

 being used to render the active medicinal constituents of 

 the bark soluble in this ni .istruum. 



3. That the bark should be exhausted of its alkaloids 

 in the process adopted, and that the extract should con- 

 tain such other constituents of the bark as are considered 

 to be medicinally valuable. 



4. That the liquid extract should contain a specified 

 quantity, say 5 per cent, of the mixed alkaloids of the bark. 



5. That the liquid extract should admit of dilution with 

 water without becoming turbid, and, on the other hand, 

 that it might be evaporated to dryness without impairing 

 its solubility to auy appreciable extent. 



In view of the numerous discussions that have taken 

 place from time to time with reference to the selection 

 and treatment of cinchona bark in its preparation for use 

 in medicine, it will not, I think, be considered necessary 

 that I should enter here into a detailed representation of 

 the advantages resulting from the accomplishment of the 

 foregoing objects. I will therefore at once describe the 

 process I have adopted, by which those objects appear to 

 be completely, easily, and economically carried into effect. 

 Extract of Bed Cinchona. 

 Take of— 



Red cinchona bark, in No. 50 powder 1 pound. 



Distilled water 4 pints. 



Hydrochloric acid J fluid ounce. 



Mix and macerate at a temperature of 180° F. for four 

 hours, stirring frequently, and replacing the water that 

 evaporates. Allow the mixture to cool ; then transfer it 

 to a percolator, and when the liquid ceases to pass, care- 

 fully introduce distilled water over the surface of the solid 

 matter in the percolator, and continue to percolate slowly 

 until ten pints of liquid have passed, or it is found that 

 what is passing has ceased to give a precipitate on the 

 addition to it of an excess of liquor soda. 



Evaporate the percolated liquid, at the heat of a water- 

 bath, until it is reduced to one pint. Let it cool, then 

 add three pints of distilled water; stir them together while 

 a precipitate is forming; separate the precipitate by fil- 

 tration; well wash the filter and its contents with distilled 

 water ; evaporate the whole of the filtered liquid at a temp- 

 erature not exceeding 180 ° F. until it has acquired a 

 syrupy consistence, and dry this either in thin Iaminee on 

 the surface of glass, or in thicker masses by exposing it 

 in shallow dishes in a drying closet. 



Dissolve 20 grains of this extract in a fluid ounce of 

 distilled water and add three fluid drachms of liquor soda. 

 Mix thoroughly and let it stand for twelve hours that the 

 precipitate may subside. Collect the precipitate on a filter, 

 wash it first with distilled water rendered alkaline with 

 liquor sodw, and, finally with water alone, and when it has 

 drained transfer it to a dish and dry it at 212 F. Its 

 weight multiplied by five will represent the percentage of 

 total alkaloids in the extract. 

 Take of Liquid Extract of Red Cinchona. 

 Extract of red cinchona, as much as con- 

 tains of total alkaloids 437'5 grains. 



Distilled water A sufficiency. 



Rectified spirit 5 fluid ounces. 



Dissolve the extract with the aid of a gentle heat in 

 twelve ounces of the water, when cold add the spirit, make 

 up the volume to 20 fluid ounces by further addition of 

 water, and filter. 



The principal object in this process has been the pro- 

 duction of a liquid extract of known and uniform alkal- 

 oidal strength, which, while it possesses the aromatic flav- 

 our and astringency of the bark, is free from much inert 

 matter, and from the peculiar extractive (chiefly quinovin) 

 which, in our official liquid extract, forms a dense, un- 

 sightly and disagreeable precipitate when diluted with water. 

 Hitherto it lias been the practice to prepare the liquid 

 Extract 60 that it shall bear a definite relation in volume 



to the weight of the bark from which it has been made ■ 

 but as it is practically impossible to ensure uniformity of 

 composition or of alkaloidal streugth in the samples of 

 bark employed, the properties of the prepared extract have 

 necessarily differed as widely as those of the barks from 

 which they have been obtained. 



The mode of proceeding in this process admits of the 

 use of any but the lowest qualities of the red barks of 

 commerce. The total alkaloids contained in the dry extract 

 produced in the first stage of the process are easily es- 

 timated, and the percentage of alkaloids being determined 

 while the extract is soluble in water, there will be no' 

 difficulty in ensuring uuiformity of strength in the liquid 

 extract. By the process as given it will contain 5 per 

 cent of mixed alkaloids in addition to the other consti- 

 tuents of the bark that are left in it. Thus a fluid ounce 

 of the liquid extract may be considered to contain all the 

 valuable medicinal properties of an ounce of red cinchona 

 bark of good average quality. 



It is obvious that the result indicated could not be ob- 

 tained without using an acid in addition to that present 

 in the bark, and there is no evidence that I am aware 

 of to show that by causing alkaloids which Would other- 

 wise be wasted to combine with 9 or 10 per cent of their 

 weight of hydrochloric acid, and thus become available for 

 use, the efficacy of the resulting preparations would be in 

 any way impaired. 



The small quantity of hydrochloric acid used in the pro- 

 cess is sufficient to ensure the entire removal of the alkal- 

 oids from barks of average, and even more than average, 

 quality. I have avoided the use of more than appears to 

 be necessary, because its action with heat is said to be 

 .injurious. A slight excess of acid would be dissipated in 

 the final concentration or desiccation to which the extract 

 is subjected. I have ascertained that by following the 

 instructions given the whole of the alkaloids extracted 

 from the bark is within a small fraction contained in the 

 dry extract in a soluble state. These alkaloids are asso- 

 ciated in the extract and also in the liquid extract with 

 other constituents of the bark which partake of the gen- 

 eral character of some of the extractive matter of the 

 liquid, extract of yellow cinchona of our Pharmaoopceia, but 

 in one respect there is a marked difference between the 

 two liquid extracts. There is nothing contained in the 

 preparations made by this process that is not freely sol- 

 uble in water, and therefore there is no precipitation or 

 tui'bidity produced by aqueous dilution. 



Having obtained several varieties of the red barks of 

 commerce for the purpose of comparing the results ob- 

 tained from them by this process, I have observed that 

 they do not all yield the same sort of extract, arising 

 from the fact that some are much richer in quinovin and 

 red chinchonic than others. The thick flat varieties are 

 the richest in those worthless constituents, while the thin 

 young bark which, having been removed from the small 

 branches with a spokeshave, is imported in small chips, 

 is comparatively free from anything that causes turbidity 

 on diluting the first concentrated extract with water. 



This result, however, does not interfere with my process. 

 The dilution would still be adopted as a safeguard, and 

 being adopted the final results will then, as far as I have 

 yet observed, be uniform or nearly so. 



The formation of dry extract as a preliminary step to- 

 wards the production of liquid extract was adopted for 

 the purpose of facilitating the adjustment of the alkal- 

 oidal strength of the latter; but the properties of this 

 dry extract which is soluble in water, forming a clear solu- 

 tion, will probably suggest its employment for other pur- 

 poses, especially where the entire absence of spirit may 

 be desired. 



In the production of the liquid extract on the large 

 scale, as well as otherwise, it is probable that manufact- 

 urers will often avoid the trouble of drying the extract, 

 and stop the evaporation when the liquid contains the 

 specified proportion of alkaloids, or carry it a little beyond 

 the required point and then dilute it to what is required. 

 There are some experimental results connected with the 

 subject which I have not yet had time to complete, but 

 I have thoughUt desirable at once to submit the essential 

 features of this process for medical and pharmaceutical 

 criticism, reserving further details for a snl.seque 

 munication. 





