CRUDE DRUGS. 421 



so-called pressed drugs ; or they are first powdered and then 

 molded into forms, as " rhubarb fingers." In some cases the 

 periderm is removed, as in a number of roots (althaea) rhizomes 

 (zingiber) and barks (ulmus). 



The QUALITY of vegetable drugs is injured by a number of 

 factors, of which the following may be mentioned: (i) lack of 

 knowledge or want of care in collecting them; (2) carelessness in 

 drying and keeping them; (3) insufficient care in garbling and 

 preparing them for the market ; (4) inattention in preserving them 

 and storing them; (5) accidental admixture in the store, and (6) 

 adulteration and substitution. 



The influence which the time of collection has on the quality 

 of vegetable drugs may be best shown by a few illustrations. It 

 is well known that when the fruits of 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 i 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 powder (Flores 

 pyrethri) know that the flowers gathered when they are closed 

 produce the finest and most powerful insect powder, 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 variation in the time of collection in dififer- 

 ent countries, as well as to its being collected from dififerent species. 



Another factor affecting the quality of vegetable drugs is 

 carelessness in drying them and caring for them after they are 

 gathered. In some cases the Pharmacopoeia 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. 



