July i, 1884.] 



ITHE TROPICAL AGRICULTURIST. 



iS 



made on chemical grounds. He would leave the pharm- 

 aceutical part of the discussion to others who were more 

 competent to deal with it. 



Mr. Giles said that he thought that it was perfectly 

 immaterial whether Professor Kedwood had changed his 

 opinion or not, but he should like to say a word for the 

 much abused old liquid extract. Some time ago having 

 occasion to examine liquid extract of cinchona he ob- 

 tained specimens of all the preparations known to the 

 market, and amongst them, two samples of the Pharma- 

 copoeia liquid extract, one from a highly respected retail 

 house, and the other from a manufacturing firm. The 

 former contained 1498 per cent and the latter P860 per 

 cent of basic alkaloid. Pharmacopceia Calisaya bark ought 

 to contain 2 per cent of basic alkaloid ; and if those ex- 

 tracts which he examined were made from Pharmacopoeia 

 Calisaya they showed a very good result, for they contained 

 nearly all the alkaloids that ought to have been present in 

 the bark. He also examined some extracts which were very 

 much advertised as being superior preparations. One of 

 these contained 1*495 per cent of the alkaloids, and this was 

 by far the highest percentage among those much advertised 

 preparations. Battley's preparation gave a higher percent- 

 age, but for certain reasons he did not include it in the 

 category. Hence, having regard to the lights which existed 

 fourteen years ago, when the Pharmacopoeia was compiled, 

 the old Pharmacopoeia preparation was not so disreputable. 

 His experience was that medical men had very great faith 

 in the old liquid extract when it was properly prepared. 

 He believed that the reason was that the bark contained 

 constituents of very great value, which were not alkaloids. 

 What was wanted was a preparation of bark. If simply 

 the active principles were required the alkaloids themselves 

 could be used. He was very suspicious when he heard his 

 friend, Professor Kedwood, proposing to turn out what he 

 called "quinovin." It was a dangerous thing to begin turn- 

 ing out anything, and he did not see the necessity for it. 

 With regard to the mode of preparation, he was very sus- 

 picious about the direction to macerate at a temperature of 

 180 ° F. His experience was that no good was to be got 

 from a high temperature. Another part of the'process given 

 in the paper consisted in adding distilled water to the con- 

 centrated percolate and stirring together while a precipitate 

 was forming. But he did not see why there should be any 

 precipitate formed at all. He had evaporated large quanti- 

 ties down to a solid extract, which he found prefectly 

 soluble. It was true that he did not use a temperature 

 of 180 ° and that the evaporation was performed iii vacuo. 

 He questioned whether the process of precipitating by soda 

 in the manner directed for estimating the percentage of 

 alkaloid in the solid extract would be found to be reUable. 

 He thought the precipitate so obtained would be likely to 

 consist largely of cinchotanuate and would give too high a 

 result ; but that was a detail which might be amended. His 

 impression was that they knew very little about bark, and 

 that it was a rash thing to say what part of it had a medicinal 

 value and what part of it had not. He held that all the 

 surroundings of the alkaloids were important, and that the 

 real object in making an extract was to get out all that 

 was soluble and could be retained in the solube condition. 

 It was an easy thing for the Professor to cut the Gordian 

 knot, by precipitating some of the material and filtering 

 it out if he could not keep it in solution, and thus to obtain 

 a soluble residuum. A soluble preparation might always be 

 obtained in that way, but he did not think that that was 

 a fair way of overcoming the difficulty. The Professor 

 said, " The small quantity of hydrochloric acid used in the 

 process is sufficient to ensure the entire removal of the 

 alkaloids from barks of average and even more than aver- 

 age quality." He doubted that statement entirely. He did 

 not know whether Professor Kedwood had examined the 

 marcs afterwards ; but he (Mr. Giles) had often found 1 

 per cent of alkaloids left in a bark containing originally 7 

 or 8 per cent, although hydrochloric acid was used and the 

 percolation was conducted precisely as directed in the present 

 paper. 



Professor Kedwood said that he was prepared to show 

 that there were no alkaloids left in the liquid. 



Mr. Giles said that the recognition of the use of hy- 

 drochloric acid was an important advance in the process. 

 Unless an acid was used there would be a waste of alkal- 

 oid, With all due respect to Dr. Paul, he believed that 



the hydrochloric acid dissolved the cinchotanuates of the 

 alkaloids as ciucbotannates. He knew that, having dissolved 

 them out, they could be got back again as ciucbotannates, 

 though that did not show that they had not undergone 

 a change in the meantime. 



Mr. Holmes said that he had tasted the extract on the 

 table, and he found that the astringency had not been 

 destroyed by the hydrochloric acid. He believed that 

 hydrochloric acid was always present in the gastric juice, 

 and therefore if the preparation was not submitted to the 

 action of hydrochloric acid before it entered the stomach, 

 it certainly was afterwards. 



Mr. Dunstan said that he should think it extremely probable 

 that the hydrochloric acid decomposed the cinchotanuates, 

 forming cinchotannic acid and chlorides of the alkaloids. 

 He supposed that when Mr. Giles said that he could get 

 back the cinchotannates, he meant by the addition of am- 

 monia. 



Mr. Giles said that he got them back by treating with 

 acetate of soda. 



Mr. Dunstan, resuming, said that that amounted to the same 

 thing. Assuming that they could not get the cinchotannates 

 out by water alone, the next best thing was to get out 

 the cinchotannic acid and the alkaloid separately. That 

 seemed to be what Professor Kedwood did. He was struck 

 with one point in connection with what Professor Kedwood 

 supposed to be the necessity of making a solid extract of 

 cinchona. It seemed to him that a standard liquid extract 

 could more easily be got by estimating the alkaloid in the 

 strong solution, and then diluting it to the requisite extent. 

 He supposed that it was a troublesome operation to evaporate 

 the solution to dryness. On the other hand, if it was thought 

 desirable to have a soluble solid extract in medicine it seemed 

 unnecessary, if this were standardized, to have a separate 

 liquid extract. During the reading of the paper he recol- 

 lected very forcibly a remark made by Professor Huxley, 

 which was that a scientific man should be strangled when 

 he arrived at the age of fifty, for he then became an 

 obstacle to progress. Professor Kedwood, however, was a 

 proof to the contrary, for he was now taking a decided 

 step in the direction of progress in advocating a standard 

 liquid extract which contained a specific amount of alkaloid. 



Professor Bentley said that he imagined that the great 

 advantage of 'using succirubra bark wa6, first, that it con- 

 tained a good amount of alkaloids; secondly, that it was 

 -not very liable to vary; and thirdly, that a regular supply 

 could be obtained. And in addition to these advantages 

 it was a bark which could be readily recognized, and it 

 could be generally procured free from any serious adulteration . 

 Those were very important considerations in the selection 

 of a bark for general use. Succirubra had high authority 

 for its use, for Dr. Fliickiger recommended it some years 

 ago, although he said that in certain respects it was not 

 equal to some other barks. It was the sole bark recognized 

 in the German Pharmacopteia, and it had been introduced 

 into the Pharmacopceia of the United States. It was also 

 one of the barks mentioned in the new Paris Oodex. Mr. 

 Holmes bad also ably advocated the use of the red bark, 

 and therefore it did not come before the meeting as some- 

 thing which was unknown. He did not altogether agree 

 with his colleague with regard to the turning out of certain 

 substances. Bark contained, many constituents, and it was 

 not known how one substance might modify the action of 

 another. He was speaking exclusively of Succirubra bark, 

 which was obtained from plants cultivated in India and 

 elsewhere. 



Mr. Walter Hills, referring to the statement in the paper 

 that the author had had some difficulty in persuading his 

 pharmaceutical friends to publish their modes of preparation, 

 said that, after that discussion, and after the change which 

 had been made, they might hope that those who had worked 

 at the subject would make known some of the results of 

 their work. 



Mr. Tanner said that he was very pleased to find Professor 

 Kedwood advocating a liquid extract representing a less 

 amount of bark than the Pharmacopceia did. In the Phar- 

 macopceia preparations, four ounces of bark were used, and 

 that on all hands was shown to be an unnecessary con- 

 centration. With regard to Mr. Giles's remarks about the 

 assay of certain samples of Uquid extract, he wished to ask 

 Mr. Giles whethfer he took into account the fact that the 

 Pharniacopteia used four ounces. 



