56 
CHANGE IN TINCTURE OF IODINE. 
another compound not precipitated by water. It is found, 
therefore, on mixing this tincture, four or five months old, 
with twice its weight of water, that there still is a precipita- 
tion of iodine, but that the precipitate is three or four times 
less in quantity than that afforded by the recently made 
tincture. The supernatant liquor, in this case, however, 
will be much more highly coloured than in the other, and 
it is unquestionable that the effect of the mixture, whether 
it be given clear or with the precipitate, would be different 
from those of a similar mixture made with the recently pre- 
pared tincture. 
Lastly, if we take tincture of iodine that has been prepar- 
ed for a year or a year and a half, it will scarcely cause 
any precipitation with water, and its medicinal effects will 
be di fie rent from those of the tincture in either of the cases 
previously considered. 
I conclude from these facts, to which I have long had my 
attention directed, that the alcoholic tincture of iodine is 
a medicine liable to variations in its composition and in its 
effects, and that it ought to be replaced by a somewhat 
similar mixture, which should be made extemporaneously. 
Such, for example, as the following, in which the whole of 
the iodine would remain in solution, forming a homogenous 
mixture: 
Iodine, 5 parts. 
Iodide of potassium, 6 parts. 
Rectified spirit, 50 parts. 
Distilled water, 100 parts. 
Triturate the iodine, iodide of potassium and part of the 
water in a mortar; then add the spirit, and the remainder 
of the water. — Pharm. Jour., from Journ. de Pharm. 
