§ 102. EXAMINATION FOR INULIN 87 



cipitated in §§ 93, 94, or certain amido-acids, sucli as sclerotic 

 or cathartic acid, etc. (For the latter see § 242.) 



EXAMINATION FOR INULIN. 



§ 102. Extraction and Estimation. — It has already been mentioned 

 in § 75 that in dried drugs the majority of this carbohydrate is 

 present in the form of an insoluble modification ; in fresh it is 

 always dissolved in the cell-sap. Dried drugs may accordingly be 

 treated first with cold water as directed in §§ 71, 92, and the 

 residue digested for some time with water at 55° to 60° (not 

 higher). At this temperature inulin passes into solution. From 

 a measured volume of the aqueous extract it may be precipitated 

 by the addition of three volumes of alcohol; and if for every 

 100 cc. of mother liquor a correction of 01 gram of inulin is 

 made, it may be thus estimated with tolerable accuracy. ^ 



Characters. — Inulin is not precipitated in a gelatinous or curdy 

 form, but in a pulverulent condition. It has already been ob- 

 served that an aqueous solution is Isevo-rotatory, and that boiling 

 Avith a dilute acid converts it into laevo-rotatory fruit-sugar 

 (levulose). Inulin may be satisfactorily estimated by converting 

 it into levulose and titrating with Fehling's solution. Of course, 

 the above mentioned correction must be made. 



I should not, however, proceed to the extraction with water at 

 55° to 60° unless a preliminary experiment had indicated the pro- 

 bable presence of inulin. 



Microscopical. — In dried drugs inulin usually appears, under the 

 microscope, in the form of agglomerated masses in the parenchy- 

 matous cells. If fresh parts of jDlants that contain inulin are 

 allowed to stand for several days in strong spirit, it is deposited 

 in very characteristic sphsero-crystals, which dissolve in acid and 

 alkali without swelling. 



Inuloid, which is said to occur in spring in the rhizomes of 

 plants of the natural order Compositae, may also form similar 

 sphsero-crystals, as do also marattin and a substance found in 

 Acetabularia mediterranea which has not yet been closely investi- 

 gated. (Cf. § 81.) 



Inuloid is said to be distinguished from inulin by its somewhat 



greater solubility in water. ^ 



1 Compare my ' Materialien zu einer Monographie des Inulins.' St. Peters- 

 burg, 1870. 



- Compare Annal, d. Chem. u. Pharm, elvi. 190. 



