470 
PHARMACEUTICAL MEETING. 
Mr. Banbury would deplore another definite solution of hydrocyanic acid 
being introduced, and would rather allow the cherry-laurel water to retain its 
place, with all its uncertainty, for those who wished to prescribe it. Those who 
wanted a definite solution, could adopt the one already provided in the Phar¬ 
macopoeia. 
NOTES ON CITRATE OE QUININE. 
BY PROFESSOR ATTFIELD. 
The following prescription was recently brought to me by Mr. W. Young, 
Pharmaceutical Chemist:— 
Quiniae Sulphatis.gr. viii 
Acidi Citrici. 3i 
Potassae Citratis. 5* 
Aquae ad.Sviii Misce. 
He stated that on mixing the several materials a similar result was not always 
obtained. Occasionally the patient said the medicine was clear and bright, and 
remained in that condition so long as it was under observation. At other times 
it was clear when made, but after a day or two a layer of small crystals covered 
the bottom of the bottle to the depth of a sixteenth or an eighth of an inch. Fre¬ 
quently it was turbid when prepared, yielding, on standing, a white, “chalky ” 
sediment, varying in thickness up to half an inch. 
The first point for consideration in this case was the nature of the precipitate; 
second, the conditions under which it was formed. Reflecting that the consti¬ 
tuents of citrate of quinine were present, and that the solubility of that salt in 
cold water is very slight, it was natural to suppose that citrate of quinine was 
the body precipitated. Analysis confirmed this view, and, moreover, showed 
that the precipitate was nothing but citrate of quinine,—showed that nothing 
like a double salt of potassium and quinine was formed. Citrate of quinine has 
been stated to be soluble in 820 times its weight of cold water. Eight ounces 
of water will therefore dissolve 4^- grains. But the 8 grains of sulphate of 
quinine ordered in the prescription will yield 8 h grains of citrate, half of which 
will be precipitated if the sulphate of potassium formed, or free citric acid pre¬ 
sent do not increase its solubility. This was about the amount of insoluble 
precipitate which the mixture yielded at the average temperature of 60° F. 
The temperature which, doubtless, is meant when the statement is made that 
citrate of quinine “ dissolves in 820 parts of cold water ” (Gmelin’s ‘ Handbook 
of Chemistry,’ Cav. Soc. Trans, vol. xvii. p. 292), for on making up the 
mixture when the temperature of the materials was about 40° F., 94 per cent, 
of the citrate of quinine was precipitated, the clear liquid having very little 
bitterness. On the other hand, when the temperature was 70° F. the ingre¬ 
dients could be so mixed as to yield no solid citrate of quinine for two or three 
days. This leads to the consideration of the conditions under which the pre¬ 
cipitate is formed. Temperature chiefly contributes to the result, but the 
method of mixing produces important influence. Thus, if the sulphate of quinine 
and citric acid be placed in the 8-ouuce bottle wuth most of the water, and the 
citrate of potash, dissolved or undissolved, be added last, a mixture will be 
obtained possessing the merit of brightness and clearness, but giving sooner or 
later, according to temperature, a crop of acicular crystals which sometimes 
adhere to the glass, and, therefore, do not admit of diffusion by shaking, and 
which, besides, may be sufficiently large and heavy to interfere with the fair 
apportionment of the dose of quinine on pouring the mixture into a measuring- 
glass or spoon. If the three solids be placed in the bottle, and water gradually 
