EXAMINATION OF THE BARK OF MONES1A. 
159 
spontaneously upon pieces of glass, have not allowed to be 
perceived by the microscope any sign of crystals. 
The solution of this matter does not saturate acids ; it has 
no odor, but its taste, at first a little bitter, soon occasions in 
the throat the feeling of acridity, which is well marked and 
very persistent. By means of nitric acid it is soon converted 
into a yellow friable substance, almost insoluble in cold water, 
but very soluble in alcohol, presenting much bitterness, and 
leaving, after spontaneous evaporation, a yellow residuum in 
pearly leaves, with somewhat of a crystalline aspect. This 
product appears to be similar to the resin which M. Henry 
announces he has obtained in the reaction of nitric acid with 
esculic acid; perhaps it is analogous to nitro-picric, or car- 
boazotic acid? 
When we compare the different physical and chemical cha- 
racters of the acrid principle of Monesia, there will be found 
a close resemblance between them and those of saponine, 
polygalic acid, and even, although more remotely, with sal- 
separine. 
. We have examined anew these characters, in specimens of 
saponine, polygalic acid, and salseparine, which we have 
ourselves prepared, or for which we are indebted to MM. 
Busy, Quevenne, and Thubeuf; and the results obtained with 
muriatic acid, potassa, and nitric acid, are very close. 
It is very probable, that if we can obtain, in succession, 
these different substances, well crystallized, or exempt from 
all the foreign matter which accompanies them, that the ana- 
logy will be complete. The fear of not obtaining the acrid 
matter of Monesia to submit it to elementary analysis, has so 
far prevented us from essaying this proof, which might then 
demonstrate its close alliance with saponine. Saponine, un- 
doubtedly, is an immediate vegetable principle, appertaining 
to different vegetables, and not restricted to the saponarese; 
the same occurs in other vegetables, as, for instance, in the 
case of asparagine, cafeine, piperine, &c, found in the indivi- 
duals of families removed from each other. 
Some years have elapsed since one of us has isolated, with 
