INTRODUCTORY. 
107 
conium are green they will yield over 3 per cent, of 
coniine, but when they become yellow the alkaloid 
diminishes rapidly in quantity, and, therefore, much 
of the commercial drug will not yield 1 per cent, of 
coniine. The same thing may be said of santonica: 
when the flower heads are unexpanded they will yield 
over 3 per cent, of santonin, but just so soon as the 
flower matures there is a rapid disappearance of the 
anthelmintic principle. Dealers in insect flowers ( Flores 
pyrothri ) know that those gathered when the flowers are 
closed produce the finest and most powerful insect pow- 
der, and it is worth nearly twice as much as that made 
from the half-closed or open flowers. It may be that 
the variation in quality of some of the commercial 
aconite is due to improper drying, or to the extraction 
of the active principles ; still, there is no doubt but that 
much of the trouble with this drug is due to the vari- 
ation in the time of collection in different countries, as 
well as to its being collected from different species. 
Another factor influencing the quality of vegetable 
drugs is carelessness in drying them and caring for them 
after they are gathered. In some cases the Pharma- 
copoeia specifies that the drug shall be kept a certain 
length of time before being used, as in the case of 
frangula. A similar specification should be made in 
regard to rhamnus purshiana; but since the results of 
the changes on keeping are now ascertained, and since 
a similar effect may be obtained by heating the bark 
at 100° C. for forty-eight, hours, this specification seems 
no longer necessary. 
In some drugs a sort of ripening process takes place 
in the drying, as in tobacco and vanilla. In still 
others a marked deterioration takes place if they are 
placed in heaps and allowed to ferment, as with 
lavender and most other drugs yielding essential oils. 
