140 EESmS, BITTER PRINCIPLES, ETC. 



salts precipitate it reddish-browTi from alcoholic solution. Fused 

 ^rith potash it decomposes, yielding acetic acid, phloroglucin and 

 gentisic acid. The latter is isomeric with protocatechuic acid (§ 42), 

 and is coloured deep blue by ferric chloride. An alkaline solution 

 of gentisic acid becomes red on exposure to the air ; when heated 

 it yields hj'droquinone, melting at 169°.^ 



For thujin, see Eochleder and Kawalier ;2 for rutin (insoluble in 

 ether), and rohinin, Zwenger and Dronke ;^ for luteolin, Molden- 

 hauer,* Schiitzenberger, Paraf and Rochleder. ^ 



§ 153. Julaphi and Allied Substances. — To the group of substances 

 that are soluble in ether, and can be removed by dilute alkali, 

 Init not by pure water, from the evaporation-residue of the 

 ethereal extract, there belong further some glucosidal resins 

 (§ b'6), of Avhich the jalaj^in of IjDomwa orizabensis may be taken 

 as a representative. 



Jalapin is readily dissolved by alcohol, and in alcoholic solution 

 is resolved by hydrochloric acid into sugar and jalapinol ; the 

 latter is soluble in ether, but only sparingly soluble in water. 

 The action of aqueous solution of soda converts jalapin into 

 jalapic acid ; the latter, after liberation with a strong acid, is 

 soluble in water, but only sj^aringly soluble in ether. 



Jalapinol appears to occur ready-formed in scammony, and 

 possibly in scammony-root also. 



Tampicin of Tampico-jalap resembles jalapin in most of its pro- 

 perties, but differs in composition.*^ The same may be said of 



^ Compare Hlasiwetz and Habermann, Annal. der Chera. und Pharm, clxxv, 

 62 ; Ber. d. d. chem. Ges. viii. 684 (Journ. Chem. Soc. xxviii. 572^. The 

 actual gentian-bitter is not identical with gentisin. The former is easily 

 soluble in water, is not thrown down by neutral acetate of lead, but precipi- 

 tated by ammoniacal acetate and liberated from the jireciiHtate by sulphuretted 

 hydrogen. It can be extracted with difficulty by agitation with benzene, but 

 with ease by chloroform ; ferric chloride does not precipitate it. It is sparingly 

 soluble in ether, and is said to dissolve in cone, sulphuric acid with red coloura- 

 tion, and ti) be decomposed by dilute sulphuric acid with jiroduction of sugar. 

 (Compare Kromayer, loc. cit.). 



- Chem. Centralblatt, 449, 1858. 



* Ibid. 766, 1862. Annal. d. Chem. und Pharm. Supplement, i. 257 

 (Amer. Journ. Pharm, xxxv. 32). 



* Annal. d. Chem. und Pharm, c. 180, 1856. 



'' Comptes liendus, lii. 92, 1861 ; Journ. f. iir.akt. Chemie, xcix, 433, 

 1867. 



"Compare 8pirgatis, N. Pepert. f. Pharm, xix. 452, 1870; Köhler und 

 Zwicke, N. Jahrb. f. Pharm, xxxii. 1, JSG9 (Pharm. Journ. and Trans. [3], 

 i. 444). 



