722 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[March 15, 1873. 
nitrous ether, if the precaution be adopted of using 
the HN0 3 diluted, as pointed out by myself in the 
Pliarm. Journal, 3rd series, vol. II. p. 225. 
Trusting to see this important matter taken up 
with spirit by the whole of our profession, and result 
in an appendix which will do us honour, I here for 
the present leave it. 
TINCTURE OF QUININE. 
BY T. H. HUSTWICK. 
The subject I am desirous of bringing forward 
is apparently so trivial as to have escaped, in this 
age of research, the attention of those who, from 
calling and experience, are better able than myself to 
deal with it; but considering the importance that 
apparently trivial matters sometimes possess on the 
bearings of our profession, and this in particular 
belonging to the domain of pharmacy, and being 
near to that of chemistry, will, I trust, be a sufficient 
excuse. 
Tincture of quinine has been an official prepara¬ 
tion only since 1851, but some time before then it 
was evidently recognized as an extra-pharmacopoeial 
preparation, from the fact that in vol. Y. of the first 
series of our Journal, amongst answers" to corre¬ 
spondents, a form is given for its preparation 
similar to the present one, except that it contained 
one minim of dilute sulphuric acid to each grain of 
quinine. We may suppose therefore it has long been 
a favourite method of exhibiting the alkaloid, the dead 
bitter of the quinine being modified and aromatized 
by the warm and pleasant flavour of the orange-peel; 
while the appearance, portability, and convenience of 
the preparation cause it to be held in favour by both 
patient and prescriber. It is one of the simplest pre¬ 
parations of the pharmacopoeia, being merely a solu¬ 
tion of sulphate of quinine in tincture of orange-peel, 
in which menstruum, when slightly warmed, the 
salt is, or should be, conipletely soluble; yet the 
result is not always satisfactory, sometimes there 
is considerable deposition of quinine in a crystalline 
form, and invariably a precipitate, occasionally ne¬ 
cessitating more than one filtration before it is finally 
got rid of. The directions given in the London Phar¬ 
macopoeia, 1851, are simple digestion for seven days, 
with subsequent filtration ; this, however, is insuffi¬ 
cient, the quinine salt being very slightly soluble in 
cold tincture, but in the translated edition the editor 
recommends the tincture to be slightly warmed, in 
order that complete solution may take place. This 
suggestion is embodied in the recent Pharmacopoeia, 
where the quinine salt is ordered to be dissolved 
with the aid of a gentle heat, and a subsequent di¬ 
gestion for three days. Now as the solution is com¬ 
plete on warming the tincture with the quinine salt, 
and since it is permanently effected at the first if too 
much heat be not used, what is the use of the sub¬ 
sequent digestion ? The tincture, on cooling, is very 
nearly bright, no appearance of undissolved sulphate 
being visible ; however, within a short time we have 
■evidence of a change taking place, the tincture be¬ 
comes a shade lighter in colour, and a precipitate 
shows itself. I conclude that it is to allow time 
for this precipitate to form completely and entirely, 
that the term of digestion is ordered, and then the 
extraneous matter is got rid of by filtration. Sup¬ 
posing the tincture be filtered immediately after it is 
made, a second filtration would ultimately be re¬ 
quired. I have frequently heard this precipitate 
spoken of as tannate of quinine; and that it is so 
seems to have been taken for granted, especially 
when v T e consider that orange-peel does contain 
tannin, as is shown by its behaviour with a salt of 
iron, and that tannates are generally insoluble, so 
that it is easy to jump at the conclusion that the 
precipitate in question is tannate of quinine. In 
the first volume of the Pharmaceutical Journal 
Professor Donovan is cited as an authority for 
the statement that an insoluble tannate is formed 
from a solution of quinine in tincture of orange- 
peel, as it is with tincture of cinchona. Ten years 
afterwards Mr. Bastick suggests a similar proposi¬ 
tion; and later, Mr. Squire, in his ‘ Companion,’ as¬ 
sumes the same to be the case. Whether this be so 
or not seems hardly to have been thought worth the 
■while of any one to question, till Mr. Groves casually 
mentioned, at a recent evening meeting, that he had 
ascertained the deposit hi tincture of quinine, pre¬ 
pared from fresh orange-peel, to be a salt of lime; a 
remark that will apply equally to a tincture of dried 
peel. Having often noticed a deposit in tincture of 
quinine, and vainly speculated as to its character 
and composition, this suggestion seemed to offer a 
ready solution of the question ; and such few oppor¬ 
tunities as have presented themselves to me have been 
devoted to this subject. The precipitate from four 
pints of tincture was collected on a filter and washed 
with two ounces of proof spirit hi small quantities 
at once (hi my first attempt, distilled water was 
used for washing, but I found the precipitate gradu¬ 
ally diminishing) ; this when dried, I found to weigh 
on different occasions from 16 to 26 grains; the 
variation is probably owing to different lots of peel 
being used; it was nearly all soluble in boiling distilled 
water, what was left being apparently only a mecha¬ 
nical residue from the filter. A solution of ferrous 
sulphate, containing a small quantity of a ferric 
salt, gave no evidence of tannin; both oxalate of 
ammonium and chloride of barium gave copious pre¬ 
cipitates of their respective compounds of lime and 
sulphuric acid, while exposure of the precipitate to 
a red heat produced no change beyond turning, it 
from white to ash grey, showing its comparative 
freedom from organic matter, such as quinine. 
Having so far settled the composition of. the pre¬ 
cipitate, the next question w T as, How came it. there ? 
The quinine salt furnishes one of the constituents; 
the other must be supplied either by the water of 
the proof spirit or by the orange-peel, but as I have 
always used distilled 'water, that, as a source, is out 
of the question. I am unable to find any pub¬ 
lished analysis of orange-peel, but . two . or three 
experiments seem to show that the lime is derived 
from that ingredient, for infusions both recent and 
concentrated, as well as tincture, give, ample evi¬ 
dence of the presence of lime by their behaviour 
with oxalate of ammonium. But what may be relied 
on as the most conclusive test is that afforded by the 
ash of the peel; this, when well incinerated, is to 
be treated with hydrochloric acid, evaporated to 
dryness, and the residue boiled with distilled water; 
then filtered and the oxalate added, showing at once 
that lime is present. From these premises we may 
build up a theory as to the formation of this salt; 
the q uin ine supplying the acid, and the orange-peel 
the base, a mutual decomposition takes place, which 
is doubtless completed within the three days ordered 
