944 
THE TROPICAL 
AGRICULTURIST. 
[May i| 1882. 
oids extracted from it would frequently furnish a 
notable quantity of crystals that did not resemble 
those of any of the known cinchona alkaloids ob- 
tained under like circumstance-. As the analysis of 
the total alkuloids, however, had not revealed the 
presence of any distinctive base, and as the cupreas 
are chiefly remarkable for yielding an unusually iarge 
quantity of quinidine,* it seemed probable that these 
crystals were a compound of the qumine with the 
quinidine. We, therefore, took two grains of the 
pure quinine and one grain of the pure quinidine, 
bolh yielded by the bark, and dissolved them together 
in ether. The solution furnished an abundant crop 
of the same crystals. These crystals, when collected, 
washed with ether, and converted into neutral sulph- 
ate, furnished a quantity of pure sulphate of quinine, 
and the mother-liquor from which the sulphate had 
been separated yielding a like quantity of quinidine. 
The quinine and quinidine used in the experiment 
had been carefully tested, they had each given the 
correct angle of rotation to a ray of polarized light, 
the one to the left and the other to the right, and 
the quinine had remained dissolved in ether for some 
weeks without furnishing a trace of crystallization. 
To satisfy ourselves that the power of forming this 
crystalline compound was not peculiar to the quinine 
and quinidine yielded by cuprea barks, we took some 
pure quinine prepared by ourselves from South American 
yellow bark, and also some quinine made in India 
from the calisaya grown in Sikkim. We fortunately 
possessed some pure quinidine that had been purchased 
from an eminent maker some time before cuprea 
barks came into commerce. Either of these quinines 
dissolved with the quinidine in ether furnished a 
crystalline compound identical in all respects with 
that just described. There could be no doubt, there- 
fore, that ordinary quinine and quinidine possess the 
power of combining together to form a crystalline 
compound very sparingly soluble in ether ; also that 
the compound is easily separated into its constituents 
by converting it into neutral sulphate, when the 
quinine sulphate crystallizes out by its greater in- 
solubility, the quinidine sulphate remaining in solution. 
Perhaps the easiest way of obtaining this compound 
is to dissolve 1 part of pure quinine in 30 or 40 
of ether, and add to the liquid a saturated ethereal 
solution of a like quantity of pure quinidine. Upon 
mixing, a crystalline precipitate of the body forms 
in abundance. Its solubility in ether is much less 
than that of eitber of its constituents, 100 c.c. of 
ether at common temperature only dissolving 0'5 grm. 
of it. 
It is moie soluble, however, in ethereal solutions 
of quinine or of the amorphous alkaloids, and these 
solutions frequently exhibit supersaturation very well, 
remaining clear for some hours and then suddenly 
giving an abundant crystallization. The compound, 
when isolated, may be re-crystallized from ether, 
apparently without change. Our results up to the 
present moment indicate that it contains the quinine and 
quinidine in equal proportions. Pressure of other work 
had much retarded us in the study of this compound, 
and the announcement of the newly-discovered alkal- 
oid by the chemists above-named took us somewhat 
by surprise. We at once commenced the examination 
of all the alkaloid products we have accumulated 
from several hundred samples of cuprea bark in the 
hope of getting some of the new base, but as yet 
our attempts have been unsuccessful. We have thought 
it best, therefore, to publish our results thus far, 
and reserve fur 1 her particulars for a future commun- 
ication. 
* We have nut with sevaral samples yielding over 
1 per cent of crystallized sulphate of quinidine. 
In reference to the foregoing Mr. David Howard 
wrote in the next number of the Chemical News, that 
the note by Messrs. Wood and Barret did not expluin 
the new alkaloid described by three independent 
papers, since all who have found it agreed that the 
neutral sulphate recrystallized unchanged from watc-, 
the mother liquor giving no sign of the presence of 
quinidine, See also the following letters from Mr. 
D. Howard and Mr. W. G. Whiffen and Mr. C. H. 
Wood. 
The Alkaloids of Cuprea Bark. 
Sir,— A note of Messrs. Wood and Barret in the 
Chemical News of last week may seem to throw doubt 
on the existence of the new alkaloid obserred in 
cuprea bark, and described in the paper read at the 
last meeting of the Chemical Society. The specimens, 
however, which we have experimented upon before 
publishing the results cannot have been such a com- 
pound of quinine and quinidine as is described in 
their note, as the sulphate or repeated crystalliz- 
ation showed no signs of separation into two bodies, 
but remain unchanged in solubility and action on 
polarized light. The alkaloid also failed in all cases 
to give the familiar hydriodate of quinidine and 
yielded a tartrate of extreme insolubility. If it be 
proved to possess these characters and still to be a 
molecular compound of quinine and quinidine it is 
a very remarkable phenomenon. Undoubtedly in estim- 
ating this alkaloid we must be on oar guard against 
such a combination as may easily be mistaken for it. 
David Howard. 
Sir, — In a note by Messrs. Wood and Barrett in 
the Chemical News, of January 6, they refer to the 
new alkaloid found in cuprea bark as being "chiefly 
remarkable for its property of crystallizing from an 
ethereal solution." A reference to the papers already 
printed in your Journal on this subject will shows 
that it is more remarkable in the similarity of its 
salts to those of quinine, and in the great action its 
solution exerts <>n polarized light. 
The compound of quinine and quinidine which these 
chemists have noticed in their analysis, and described 
in the note referred to, does not resemble the new 
cuprea alkaloid in any respect, and I should not 
expect it to be mistaken for that. Moreover, a com- 
pound of equal proportions of quinine and quinidine, 
such as they describe, should exert a slight right- 
handed .rotation, whereas the cuprea alkaloid is power- 
fully laevogyre to the polarized ray. 
In my experience the new base is contained in 
varying proportions in almost every sample of cuprea 
bark, and from a sample which arrived in London 
in February last I have obtained as much as -9 per 
cent of the sulphate of the new base. 
W. George Whiffen. 
Sir, — Mr. Howard in his letter in your current 
number says, that " the note of Messrs. Wood and Barret 
in the Chemical News of last week may seem to 
throw doubt on the existence of the new alkaloid 
observed in cuprea bark." I would point out, there- 
fore, that we did not make this suggestion, and did 
not in any way question Mr. Howard's results. 
We simply described a combination of quinine with 
quinidine that is crystalline and very slightly soluble 
in ether. It might be mistaken from the new alkal- 
oid, as Mr. Howard states in his concluding sentence, 
for it easily crystallize*) from an ethereal solution of 
thd total alkaloids of many cupreas, and it can yield 
a crystalline sulphate which, when isolated, may be 
as laevogyrate as quinine sulphate and give no hydio- 
date of quinidine. 
Yet, I may add, the improbabilities that you put 
