SAPONIN. 421 



ized with animal charcoal; evaporated; the crude con- 

 volvulin dissolved in alcohol, and reprecipitated with 

 ether. Colorless, resinous mass; inodorous and taste- 

 less ; fuses at 150 ; but slightly soluble in water, 

 easily in alcohol. It exerts a purgative action. Dis- 

 solves in alkalies, and is converted by them into an 

 easily soluble, amorphous substance, c'onvolvulic acid 

 (rhodeoretic acid), C 31 H 52 O 17 (?), water being assimilated 

 in the reaction. Convolvulin, as well as convolvulic 

 acid, in contact with emulsin, or when treated with 

 dilute acids, is decomposed into sugar and convolvu- 

 linol, C 13 H 24 3 + JH 2 0, which dissolves in alkalies, 

 forming convolvulinolic acid, C 13 H 26 4 . 



15. Jalapin. 



C 34 H 56 16 . 



Homologous with convolvulin. In jalap-root (of 

 Convolvulus orizabensis) and scammony-resin (the hard- 

 ened sap of Convolvulus scammonia). Very similar to 

 convolvulin. Is decomposed by emulsin or acids into 

 sugar and jalapinol, C 16 H 30 3 + 1 JH 2 ; and conducts 

 itself towards alkalies like convolvulin. 



Turpeihin, a resinous glucoside, isomeric with jalap- 

 in, is contained in turpeth-resin (from the root of 

 Ipomoea turpethum). It yields, when treated with 

 baryta- water, amorphous turpethic acid, C 34 H 60 18 , and 

 is decomposed by mineral acids into sugar and white, 

 amorphous turpetholic acid, C 16 H 32 4 . 



16. Saponin. 

 C 32 II 54 18 . 



In the root of a number of plants (Saponaria qfficina- 

 lis, Gypsophila struthium, Polygala senega, Agrastemma 

 githago). "White, amorphous powder, which causes 

 sneezing; poisonous; easily soluble in hot water. 

 This solution foams like soap-water, even when very 

 dilute. Treated with hydrochloric acid gas or fuming 

 hydrochloric acid, it yields an uncrystalline, saccharine 

 36 



