§ 1 67. BENZOHELICIN, . ETO. 1 69 



Tjenzene (§ 55). Populin decomposes vriih. far greater facility 

 than salicin. 



Benzohelicm,^ detected by Johanson in willow bark, forms colour- 

 less crystals, soluble in water and alcohol. With cone, sulphuric 

 abid it turns yellow. Frohde's reagent does not produce a violet 

 colouration, ' Boiling with not over-dilute hydrochloric acid 

 resolves benzohelicin into glucose, benzoic acid, and a resinous 

 substance that dissolves blood-red in cone, sulphuric acid. 



FhUyrin^ is much less soluble in water and alcohol than is 

 salicin, and yields under the influence of dilute acids, glucose and 

 philygenin, a polymer of saUgenin. Both phOyrin and philygeniti 

 dissolve in cone, sulphuric acid with red colouration. 



. Phhrrhizin^ crystallizes in colourless needles sparingly soluble 

 in cold water, easily in hot. Ethyl and methyl alcohol dissolve il 

 with facility, ether with- difficulty. Dilute . acids resolve it into 

 glucose and phlorrhetin. Cone, sulphuric acid forms red Solutions 

 with both phlorrhizin and phlorrhetin ; -with Frohde's reagent a 

 splendid royal-blue colouration is rapidly developed. Moistened 

 with ammonia and exposed to the air, phlorrhizin -turns yellow, 

 red, and finally blue. 



.^scvlin can likewise be obtained in colourless needles soluble 

 in 12-5 parts of boiling, 672 of cold water; in 24: of boiling, and 

 120 of cold absolute alcohol. Chloroform removes it from 

 aqueous solution (§-55). Boiling with dUute acids resolves it info 

 glucose and eesculetin. ^ The latter yields a yellow solution with 

 alk£ili6s ; it is also soluble in bisulphite of ammonia, and if such a 

 solution be mixed with ammoiiia and shaken with air, at first 

 blood-red and subsequently a deep blue colour is developed. The 

 very characteristic blue fluorescence of «escuiin is increased by 

 ■alkalies and destroyed by acids. 



Fraxin possesses a similar fluorescence, and can also be obtained 

 in colourless ■ crystals. It is more sparingly soluble in water and 

 absolute alcohol than sesculin, but more freely in ether, to' which 

 it imparts its fluorescence. Ferric chloride is said at first to stiike 



' See Johanson, he. oil. PIcia, Annal, d. Cheiu. und Pharm. Ixxxi. 215, 

 1852; xcvi. 376, 1855 (Amer, Journ. Pharm. xxiv. 241-, xxviii. 259). 



* Compare Campona, Annal. d. Chem. und Pharm, Ixxxi. 245, xcvi. 375. 



■'For lEophlorrhizuir see Eochleder, Journ. f. praofc. Chem. civ. 397, 1868 

 <Amer. Journ. Pharm. xK. 419). 



