24 
ON DRUG-GRINDING. 
posure in the drying-room, it will be difficult, if not impos- 
sible, to produce perfectly smooth and impalpable pow- 
ders, such as are now generally used in medicine. This 
drying is, of course, accompanied by a diminution of weight, 
arising from the loss of water and other volatile constitu- 
ents, which varies considerably in different drugs, and also 
in different specimens of the same kind of drug. There is 
always, however, a little moisture again absorbed during 
the process of grinding. 
There are some drugs which, however carefully they 
may be dried, are, nevertheless, with great difficulty reduced 
to powder by the ordinary method of proceeding. Nux 
vomica, St. Ignatius's beans, and the tuberous root of the 
orchis, belong to this class. They are tough and horny, 
and can hardly be powdered without a particular treat- 
ment. The best method of preparing nux vomica and St. 
Ignatius's beans for pulverization is to expose the seeds to 
the action of steam until they have swelled to about twice 
their original size, and then to dry them rapidly in the dry- 
ing room. The roots of the orchis, which are ground to 
make saloop-powder, should be macerated in cold water 
until they have become soft, and then dried, as in the other 
case. After being thus treated they are easily powdered. 
Some substances cannot be powdered alone ; they re- 
quire the addition of other bodies which facilitate the disin- 
tegration. Thus the addition of a few drops of spirit ren- 
ders the pulverization of camphor easy, although it could 
not be effected without it. Agaric is a substance which it 
is extremely difficult to powder alone, and a method has 
therefore been proposed for powdering it by mediation. 
It is cut into small pieces, wetted with mucilage of traga- 
canth, and then dried, previously to submitting it to the pro- 
cess of grinding. The addition of a foreign body, which the 
powder retains, cannot, however, be sanctioned, excepting 
under particular circumstances, such as the impossibility of 
otherwise effecting the object. It is stated in some phar- 
