182 plant and organic chemistry 
a boiling heat during this period. It is a rapid way to deter¬ 
mine qualitatively what constituents are to be found in any 
plant, and this may be followed by a careful quantitative study 
on larger amounts. The general insight which can be ob¬ 
tained of the chemistry of a plant from this small quantity 
of material serves as a valuable guide for the future study on 
a larger scale. 
The extracts obtained by heat show more proneness to 
oxidation than those from cold maceration, and there are some 
slight differences in the character of the extracts. The ten¬ 
dency of the higher temperature is to increase the number 
of constituents in the first extracts; i. e., hot petroleum-ether 
will remove a considerable quantity of chorophyll; hot ether 
will extract tannin, and hot alcohol extracts contain sugar, 
saponin, etc. After the hot alcoholic maceration, the water, 
dilute soda, and acid extractions are conducted at the ordi¬ 
nary temperature. 
It will depend somewhat upon the object in view on the 
part of the analyst what course to follow in the study of a 
plant. If only one compound is to be isolated and examined, 
disregarding the other constituents, suitable methods of study 
will be employed for this end. Even when Dragendorff’s sys¬ 
tematic scheme is followed, a fresh portion of powder should 
be extracted with water for an accurate estimation of soluble 
albuminoids, amides, and other classes of nitrogenous com¬ 
pounds. These subjects are very clearly stated in the volume 
of “Plant Analysis,” to which I have referred. 
I wish to bring forward some well-known statements, which 
may serve to illustrate the practical application of facts dis¬ 
covered by plant analysis. One of the more recent applica¬ 
tions of new processes to industrial chemistry is the manu¬ 
facture of hop-resin extract 1 on a large scale. The use which 
is made of this extract is in the manufacture of beers, and 
it is being used to a large extent in Philadelphia and New 
York, fully supplying the place of the ordinary hop. The 
process is somewhat as follows: The hops are loosely placed 
1 “Hop Extract,” by W. B. Bisseil, Am. Jour. Pharm., April, 1885, p. 
