i8o PLANT AND ORGANIC CHEMISTRY 



but a system by Osse 1 has been devised to evaporate the pe- 

 troleum-ether and save the volatile oil. 



Distillation of volatile principles may be sometimes sub- 

 stituted by other methods, such as "infusion" and "enfleur- 

 age," of which I shall speak later. 



The following is the general plan I usually follow, based 

 upon Dragendorff's scheme, in order to determine the con- 

 stituents of any plant. Twenty, fifty, or a hundred grams of 

 the dried powdered plant are weighed and macerated with suc- 

 cessive solvents. The solvent is added in the proportion of 

 ten c. c. to one gram of powder. This is allowed to stand, 

 with frequent shaking, for eight days, when the liquid is re- 

 moved with a pipette or filtered from the powder. The residual 

 powder is then rinsed with more of the solvent, which, added 

 to the extract first obtained, is made to a known volume. 

 The powder is dried at the ordinary temperature, and is then 

 ready for maceration with a second solvent, and so on, until 

 the sequence of solvents has removed all soluble matter from 

 the powder. The residual insoluble portions are cellulose, 

 lignin, and other allied substances, which form the firm frame- 

 work of the plant. 



The solvents used must be chemically pure. The order 

 of solvents recommended by Dragendorff, and the classes 

 of compounds which may be extracted by them are given in 

 the table. 



PETROLEUM-ETHER EXTRACT 



Ethereal oils; volatile fat acids; glycerides; waxes; cam- 

 phors; cholesterin or allied substances; chlorophyll and 

 alkaloids with fixed oils; aldehydes; ethereal salts; alcohols; 

 aromatic acids; resins. 



ETHER EXTRACT 



Resins; waxes; fats; chlorophyll; coloring- matters; organic 

 acids; glucosides; alkaloids (caoutchouc, chloroform, or bisul- 

 phide extracts). 



\ 



1 Archiv. d. Pharm. (3), vii, 104 (1875). (Year-Book Pharm., 1876, 362.) 



