142 
contained Tittle calcareous matter, some magnesia, and a smali | 
portion of ‘silex. : | 
6. Though no aroma or Seacrenite of any kind was perséptible 
in the barks, I placed two ounces of them for distillation in 
water, to ascertain if they contained any essential oil; and 
though I purified the distillation, nothing was ebservable on the 
surface of the water when placed in a narrow-necked vessel. — 
7. From what is here stated the result is, that in the barks of 
the root of the Yallhoy the extractive principle is most abundant, 
and in it resides the stimulant virtue perceptible in the bark it- 
self; that this extractive principle is mixed witlra little mucilage, 
for which reason at first the acrid flavour is not noticed, which 
is afterwards experienced on chewing the root, and which is sub- 
sequently manifested when after dilution of the mucilage the 
extractive principle is separated. For the same reason the 
acrid bitter flavour is not perceptible in the aqueous as in the 
spirituous infusions, because in the former the two principles. 
remain united, and in =~ latter the extract alone is disen- 
Saged. 
8. That the stimulus and the virtues of the bark reside. in 
the extractive principle, is proved by its property of dissolving 
in water, and in pure spirit of wine or alcohol, and by its aae 
lity of oxygenization ; 3 since on adding a few drops of nitric 
acid to a little of the infusion, its colour changed after some 
time ; and it is va known, that the extractive principle is: 
that which suffers most modifications by the oxygen, igbie: re- 
gularly a duller colour when exposed to the open air. — 
9. I lastly proceeded to examine the extract, for the purpose. 
* ascertaining whether (as I suspected) the extractive principle 
abounded in it. I remarked that a portion of it did not dissolve. 
in water; and as I was sure that this residuum was ‘not burnt, 
