Mr. E. A. Parnell on the Composition of Inulin. 127 



Angelica Arclia?igelica, Colchicum antumnale, Helianthus tube- 

 rosus, &c, and in a few lichens, as L. fraxineus and L..fasti- 

 giatus. Although known to be closely related to starch, and 

 interesting as a probable member of the starch family (espe- 

 cially in being converted into gum and starch sugar by the 

 action of dilute acids), no examination of its composition has, 

 as far as I am aware, been made. To supply this deficiency, 

 I have performed a few analytical experiments on inulin and 

 its compounds, the results of which form the subject of the 

 present communication. 



The inulin analysed was prepared from the root of the 

 dahlia, as follows : the moist root, with the skin previously 

 removed, was sliced, macerated, and washed with cold water. 

 This was boiled in five parts of water for about an hour and 

 a half, and filtered. The solution was nearly colourless, and 

 quite neutral to test paper*. It was then evaporated until a 

 pellicle appeared on the surface, and on setting aside to cool a 

 large quantity of inulin was deposited in the form of a white 

 pulverulent precipitate. This was collected on a calico filter, 

 and washed with cold water until all the salts present were 

 removed. It was then perfectly tasteless. Dried at a gentle 

 heat, it became gummy, transparent, and easily pulverised ; 

 very soluble in hot, but sparingly in cold water. The liquid 

 filtered from the first deposit of inulin gave an additional quan- 

 tity on evaporation, which was obtained pure by washing, re- 

 solution, and evaporation. 



That used in the two first analyses was prepared by adding 

 alcohol to a strong aqueous solution ; on standing the inulin 

 was deposited perfectly pure. That used in the third analy- 

 sis was made without alcohol. 



1st. — 6*70 grains gave 10*65 carbonic acid, and 3*824 water. 



2nd.— 6*82 , 10*87 ' 3*960 ... 



3rd. — 7*38 11*72 ...... 4*260 ... 





1. 



2. 



3. 



Mean. 



Carbon . . . 



43-95 



44*07 



43*90 



43*97 



Hydrogen . 



6*34 



6*45 



6*41 



6*40 



Oxygen . . . 



49*71 



49*48 



49*69 



49*63 



100*00 100*00 100*00 100*00 

 This nearly approaches the formula C 24 H 21 21 ; thus 



* Payen directs chalk to be added, a free acid being present. 



