ON DRUG-GRINDING. 
27 
If no active constituents be lost in the drying process, the 
strength of the powder will be greater than that of the crude 
drug, to the extent of the quantity of water and inactive 
matter which have been separated and rejected. It would 
be very desirable to ascertain what the average increase of 
strength is in those drugs which suffer no deterioration in 
the process of powdering; and also what is the exact nature 
of the deterioration necessarily sustained by drugs, such as 
myrrh, ginger, cardamoms, and cascariila, which contain f 
and must therefore lose active volatile constituents. 
Next to the preservation of the medicinal efficacy of the 
drug, the most important object for attainment is uniformity 
of strength in the product. What security has the physi- 
cian that a grain of opium or ten grains of jalap obtained 
from a particular source shall be equivalent to the same 
quantities of those substances obtained elsewhere. 
There are several causes which tend to affect the uniform- 
ity of the strength of those medicines which consist of parts 
or^crude products of plants. In the first place, these drugs, 
in their natural or original state are not uniform in compo- 
sition and properties. Different specimens of cinchona bark 
yield very different proportions of the alkaloid upon which 
the efficacy of the drug depends — other drugs differ to an 
equal extent ; in fact, what drug can be mentioned of which 
there are not good and bad specimens, in their natural state, 
to be met with in the market? The practical knowledge 
and experience of the druggist are called into requisition in 
selecting the good from the bad, and thus two classes, at 
least, are formed. There may be some approach to 
uniformity in each of these classes, but what uniformity is 
there between them? It must be admitted, however, that 
the criteria of excellence usually adopted in these cases 
are often founded upon qualities of an extrinsic character, 
which have no definite relation to medicinal properties. 
Passing, then, from this source of disparity in quality and 
strength, and having selected the best specimens of the 
