244 ON THE TINCTURES OF CATECHU, KINO, AND KRAMERIA. 
specimen should be selected for experiment, for it is well known that this 
tincture frequently becomes gelatinous if kept, and deteriorates in quality. 
If the air be excluded the tincture keeps for a long time without under¬ 
going change, therefore the U. S. Pharmacopoeia directs that “ This tinc¬ 
ture should be renewed frequently, and kept in closely stopped bottles.” 
Though the exact chemical decomposition which occurs has, up to this, 
eluded explanation, the change is possibly due to slow oxidation, and ac¬ 
cording to Dorvault, the jelly consists of pectic acid (L’Ofhcine de Pharm. 
Prat., Paris, 1847, p. 309). 
Pereira suggests that when this tincture solidifies, the Botany Bay kino 
(inspissated juice of Eucalyptus resinifera) had been employed. (4th edit, 
vol. ii. part ii. p. 327.) Even tincture of catechu is said sometimes to gela¬ 
tinize when kept; similarly also, tincture of rhatany, according to F. Boudet 
and others. (Journ. de Pharm. 3 ser. i. 338.) In my first experiments the 
tinctures * w r ere mixed with an equal volume of distilled water, and the re¬ 
sults were noted, which, however, were not satisfactory, for all the tinctures 
■were rendered opaque, the tint varying from light brown to the colour of 
dark porter. 
In subsequent experiments each tincture was diluted with seven volumesf 
of distilled water, and it was then observed that while tincture of kino yielded 
an abundant fiocculent precipitate, the tincture of catechu assumed a dark 
garnet-red, and the tincture of rhatany a bright garnet-red. But these two 
latter are easily distinguished at a glance, for tincture of rhatany remains 
permanently transparent by reflected and transmitted light, and tincture of 
catechu, on the contrary, is opaque by reflected light from the first, and on 
standing for some hours becomes equally so by transmitted light. The results 
obtained by allowing a few drops of each tincture to evaporate spontaneously 
in watch-glasses are also individually characteristic, and are more easily 
judged of by the eye than conveyed by description. 
The tabular view on page 245 will exhibit more clearly their distinctive 
characters. 
Column I. represents the characters of the specimens obtained from Lon¬ 
don, and Column II. those of the specimens furnished by Dublin, and which 
coincided essentially with each other. 
Some discrepancies were observed in the course of the experiments, which 
require a few words of comment. 
The results, for instance, of evaporating the samples of tincture of catechu 
are seen to be strikingly different, but are, I think, easily explained by a 
reference to the varieties of catechu in the market. 
The tincture of Catechu pallidum (the only officinal kind), when the spirit 
is driven off, leaves an opaque residue ; but that of Catechu nigrum (which 
hs probably often substituted for it) leaves a transparent residuum. (See 
Here, then, we have an easy criterion of judging whether, in any given 
case, the directions of the British Pharmacopoeia are complied with or not, as 
regards the preparation of this tincture.£ 
* As none of these tinctures were freshly made, and they had all been constantly exposed 
to direct sunlight for some time, it is quite possible that they may have undergone some change 
attended with an alteration in properties. 
t Seven volumes of water were preferred, among other reasons, because many tinctures 
are prescribed in the proportion of one fluid drachm in one fluid ounce as a draught or in a 
mixture. 
X I obtained a specimen of the catechu used by one of the Dublin houses (Column II.) in 
the preparation of the tincture, and found it to answer to the variety of Acacia Catechu, U.S., 
described by Dr. Wood as plano-convex or cake catechu. 
