Preservation of Tinct. Kino from Gelatinizing.
By J. W. WOOD, Rokeby, Del.
Among all our tinctures, perhaps there is not one so liable to deteriorate by exposure, or by long keeping, as tincture of kino, made in accordance with the U. S. Pharmacopoeia; its well known property of gelatinizing in a short time—a property which yet remains to be investigated—being thereby rendered inert, precludes it from being as extensively used as its virtues would seem to warrant.
This property renders it inadmissible when we desire a reliable tincture, to prepare it in large quantities.
The pharmacopoeia formerly directed it to be prepared with dilute alcohol as the menstruum; but later it was thought to be of advantage to increase the proportion of alcohol to two thirds; yet it is doubtful if there was much gained by this change.
I would therefore submit the following mode of preparation, which I consider, from the experience I have had, will meet with the desired end, and up to the present time results do not seem to disprove it. It is as follows:
| Rx. | Kino in fine powder | ℥iss |
| Alcohol .835 | f℥viij | |
| Aquae | f℥iv | |
| Glycerinae | f℥iv |
Mix the alcohol, water and glycerin together, and having mixed the kino with an equal bulk of clean sand, introduce in a percolator and pour on the menstruum.
This menstruum seems to thoroughly exhaust the drug of its astringent principle, and also makes a nice looking preparation.
Some which I made on the sixteenth day of July, 1870, was exposed to the influence of the atmosphere, the stopper of the bottle containing it having been removed for several months, so that it had evaporated to at least two-thirds; yet it remains as good as when freshly made, without any apparent tendency to gelatinize.
The menstruum might be somewhat modified, perhaps with advantage, as, for instance, by using proportionally less alcohol and more glycerin and water, or vice versa. At any rate I will give it for what it is worth; adding at the same time the suggestion—and it is only a suggestion—that the same menstruum be employed in preparing tinct. catechu, which, though not so liable to gelatinize as tinct. kino, yet sometimes does so.
