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 DragendorfFs 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 * 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. Bissell, Am. Jour. Pharm., April, 1885, p. 

 1 66. 



