14 



<THE TROPICAL AGRICULTURIST. 



[July i, 1884. 



DISCUSSION. 



The President, in inviting a discussion, suggested that 

 it should be confined exclusively to the subject of liquid 

 extract of cinchona. He would only say, in passing, that 

 the Professor had very ingeniously dropped his old friend 

 and taken to the new one. He should be glad if he had 

 thrown his first love over with something like courage. 

 Possibly there were some gentlemen present who might 

 have something to say for the so-called liquid extract of 

 cinchona which now existed in the Pharmacopoeia. "With 

 'all due respect to the Professor, he must say that he had 

 weakened the force of his argument by the first two 

 paragraphs of his paper, for, in one place he referred to 

 the value of the existing preparation, and then he stated 

 in so many words that practically it was not very valu- 

 able. 



Mr. Giles requested that before the discussion com- 

 menced, Professor Redwood would state what he meant by 

 quiuovin. 



Professor Redwood said that he found that the term 

 was very generally used to represent a bitter amorphous 

 extractive matter which was capable of being taken out 

 from cinchona barks, and which after concentration was 

 precipitated by dilution. 



Dr. Paul said that he had listened to the paper with 

 very great surprise, on account of the remarkable dis- 

 crepancy between the statements contained in it and the 

 position which Professor Redwood took up with regard 

 to the liquid extract of cinchona on a previous occasion. 

 About a year ago be (Dr. Paul) brought before the meet- 

 ing some data which led him to conclude that the liquid 

 extract of cinchona was not altogether what it was com- 

 monly believed to be, or what he believed such a pre- 

 paration ought to be hi regard to the drug from which 

 it was prepared. One objection which be raised against 

 the liquid extract of the Pharmacopoeia was its invariable 

 deficiency in the amount of alkaloids which it ought to 

 contain, and that therefore the recommendations which 

 were given of it were misleading to medical men. On 

 that occasion Professor Redwood defended the preparation 

 and the method of preparing it, and he characterized the 

 objection that it did not contain the medicinal constituents 

 of the bark as a very weak objection. The present paper, 

 however, appeared to be a perfect recantation of the 

 position which Professor Redwood previously took up. , 

 He now said that there was a strong ground of objection 

 to the official mode of preparing liquor cinchona. That 

 was precisely what he (Dr. Paul) had said a year ago. 

 Indeed, Professor Redwood's present statement appeared 

 to be a confession which admitted all the charges which 

 he (Dr. Paul) made against the preparation and the pro- 

 cess by which it was prepared. The Professor might, 

 however, have been somewhat more candid in his con- 

 fession than he had been. In consequence of the vigorous 

 defence which Professor Redwood made on the last 

 occasion, he (Dr. Paul) was discouraged from following 

 out the matter and had remained passive ever since. His 

 objections to the official process were not received with 

 favour, and there did not seem any prospect of a proposed 

 substitute being better received ; therefore when Professor 

 Redwood spoke of the difficulty which he had had to get 

 his freinds to undertake the investigation of the subject, 

 it must be remembered that the difficulty was somewhat 

 of his own creating. In commenting upon the chief ob- 

 jection to the liquor cinchona?, that it did not contain 

 all the medicinal constituents of bark, Professor Redwood 

 instanced the infusion of camomile and asked who in his 

 senses would think of objecting to that infusion because 

 it did not fully represent all that was active in the camomile 

 flower. It was remarkable that, after such a brief lapse 

 of time, he should now come forward and abandon his 

 former position and recommend the present preparation, 

 because it fully represented the medicinal efficacy of the 

 bark. It could not be supposed that in this short space 

 of time the Professor had taken leave of his senses, and 

 yet he now came with a recommendation which only a 

 year ago he characterized as senseless. Then as to the 

 material from which the new preparation was to be made, 

 they were told that it was red bark. But what red bark? 

 Certainly not the red bark of South America, which, how- 

 ever valim : >V it might be for making tooth powder, had 

 tie febrifuge value, and would not serve for making 



_, 



the liquid extract. He apprehended that the bark used 

 was the Indian red bark, which a year ago he was told 

 was so utterly outside the pale of official pharmacuetical 

 recognition that he was making an uuwarrantable assump- 

 tion in presuming to bring forward experiments made with 

 that bark to show that the process in the Pharmacopoeia 

 was useless. His experience of the red bark of India, 

 notwithstanding the favour with which it was regarded by 

 some persons, was that it was about the worst bark which 

 could possibly be used. It contained much objectionable 

 material, which resembled extract of kino more than any- 

 thing else, and he should judge that it was about the most un- 

 suitable uf 3ny for pharmaceutical purpose. There was 

 plenty of cinchona bark of the true calisaya or officinalis 

 type, which he regarded as preferable, and which possessed 

 the advantage of having very little of the red offens- 

 ive looking and nauseous material which was preci- 

 pitated by water ; such bark contained a large percentage 

 of alkaloid in which quinine preponderated. They were 

 told at the last discussion that the reason that he obtained 

 unfavourable result? was a material not ordered in the 

 Pharmacopoeia. He (Dr. Paul) took it that in the 

 lapse of time Professor Redwood had recognized the 

 validity of the objections which he (Dr. Paul) raised on 

 the former occasion, and that he had now sought to devise 

 a process by which those objections could be avoided. 

 As to the process itself, it consisted in treating Indian 

 Succirvbra hark, he supposed, not with water, but with dilute 

 acidg He could not accept the representation that this was 

 an aqueous treatment, seeing hydrochloric acid was employed. 

 He should like to see some olata which would enable them 

 to judge how far the preparation, made with hydrochloric 

 acid, really did represent the bark in every respect. That 

 he believed to be the chief point about the whole of the 

 preparations of bark. A great deal had been said about 

 the relative efficacy of different preparations and medical 

 opinions with regard to the water preparations had been 

 alluded to. No doubt those opinions were deserving of 

 respect, although they were not altogether intelligible in 

 the present state of our knowledge. It appeared that the 

 very strong predilection amongst medical men in favour of 

 the decoction was due, not to the constituents which it 

 contained, but to the manner in which the constituents 

 were presented to the stomach. In all kinds of cinchona 

 bark, he believed, the principal part of the alkaloids was 

 in combination with cinchotannic acid, and in that form 

 of combination the alkaloids were very sparingly soluble in 

 water. The consequence was that the infusion which was 

 made with cold water was the weakest of any; the decoction 

 was stronger, but though the solubility of the cinchotannates 

 was greater in hot water than in cold, a large quantity 

 of cinchotannate was deposited when the water cooled. "What 

 remained was in the same state of combination as in the 

 bark itself, and that, he bolievcd, was one of the reasons 

 why the decoction was preferred to any other preparation. 

 With regard to the liquid extract, he thought that the 

 same condition ought to be maintained, and that an attempt 

 should be made to avoid the elimination of the cinchotannic 

 acid, and its decomposition, which took place very readily 

 when it was liberated, so as to obtain a solution of the 

 alkaloids in the state in which they existed in the bark. 

 Professor Redwood had spoken of certain "worthies" con- 

 stituents being eliminated. He (Dr. Paul) failed to see on 

 what authority Professor Redwood condemned those con- 

 stituents, or why he assumed that the alkaloids contained 

 in his finished preparation were in the state in which it 

 was desirable they should exist. This must be left for further 

 inquiry. His (Dr. Paul's) own opinion was that the use of 

 hydrochloric acid in preparing liquid extract was deckledly 

 objectionable. Professor Redwood had stated that there was 

 nothing in the preparation made by the process which he 

 had now described which was not freely soluble in water. 

 Consequently there was no cinchotannate of the alkaloid, 

 and it might be inferred that this had been decomposed. 

 This was in fact shown by the absence of turbidity on 

 diluting the new preparation with water. The cinchotannate 

 was, however, precisely the constituent which it was desirable 

 to retain in a liquid extract. As to the exhaustion of the 

 bark, there were no data showing that the new process 

 was efficient. He was inclined to doubt whether treatment 

 with weak acid would extract the whole of the alkaloids. 

 The objections which he urged to the process were chietly 



