926 Wisconsin Academy of Sciences, Arts, and Letters . 
the preparation of the various oleoresins will be discussed in 
a general way under methods of preparation and in detail under 
individual oleoresins. 
Methods of Preparation 
The methods of preparing the oleoresins as outlined in the 
present edition of the United States Pharmacopoeia may he 
stated in the following general way: extract the drug com¬ 
pletely 1 ) by percolation, expose the percolate in a warm place 
until the solvent has completely evaporated and separate the 
remaining liquid portion from any deposited material. This is 
essentially the method of procedure given in most of the late 
editions of the foreign pharmacopoeias as well, notable excep¬ 
tions being the German and Japanese. In the two latter, the 
drug is directed to be exhausted by maceration instead of per¬ 
colation. In detail, the methods described in the United States 
Pharmacopoeia, as well as the foreign pharmacopoeias, differ 
somewhat with the particular oleoresin as will be brought out to 
some extent in the following discussion and more minutely 
under the separate treatment of each individual. It is perhaps 
needless to state that these methods are not of recent invention 
but have been gradually evolved from the numerous experiments 
conducted both in this country and abroad. 
The first of these experiments dates back to the year 1825, 
when Peschier prepared the Huile de Fongere Male, our pres¬ 
ent oleoresin of aspidium. In his description of the method of 
preparation, he directs that the male fern rhizomes be extracted 
with successive portions of ether, the decanted ethereal solu¬ 
tions mixed and evaporated at a gentle heat, and the remaining 
oily residue collected and preserved as the finished product. 
This is essentially the method which appeared in the early 
European pharmacopoeias as is shown in the following typical 
example taken from the Prussian Pharmacopoeia of 1830: 
Agitate one ounce of powdered male fern root with successive portions 
of eight ounces of ether until the ether decants clear. Then mix the 
several portions and strain. Distill down to one-fourth of the volume 
and evaporate the remainder on a water bath to a thin yellowish-brown 
extract. 
1 Percolation, in the extraction of capsicum is directed to be discontinued 
when eight hundred mills of percolate have been obtained. 
