446 CONVOLVULACEJE. 



Convolvulinol, C^H**'0^ and sugar. Convohmlinol in contact with 

 aqueouj alkalis is converted into Convolvidhiolic Acid, C-'^H^^O^ 

 which is slightly soluble in water and crystallizable. 



When convolvulin or its derivatives is treated with nitric acid, it 



yields several acids, one of which is the Sebacic Acid, C^W^ J. pqqtt 



which is to be obtained by treating castor oil or other fatty substances 

 in the same manner. Sebacic acid forms crystalline scales, soluble in 

 boiling water, melting at 128°. That from jalap was first thought to 

 be a pecujiar acid, and therefore termed ijwmic or i^ionioeic acid. Its 

 identification is due to Neison and Bayne (1874). 



Convolvulin (dry) melts at 150° C., but a small amount of water 

 renders it fusible below 100° C. It is insoluble in oil of turpentine and 

 in ammonia. It dissolves in dilute nitric acid without becoming coloured 

 or evolving gas. Convolvulin possesses in a high degree the purgative 

 property of jalap, but this is not the case with convolvulinol. 



The other constituents of jalap include starch, uncrystallizable sugar, 

 gum, and colouring matter. The sugar, according to Guibourt, exists to 

 the extent of 19 per cent. 



Commerce — We have no means of knowing to what extent jalap 

 is produced in Mexico. The imports of the drug into the United King- 

 dom amounted in 1870 to 169,951 lb. Very considerable quantities 

 have of late (1873) appeared in the London drug-sales. 



Uses — Jalap is employed as a brisk cathartic. 



Other kinds of Jalap. 



Besides true jalap, the roots of certain other Convolvulacece of Mexico 

 have been employed in Europe, either in the form of jalapin, or as adul- 

 terants of the more costly, legitimate drug. The two following have 

 been extensively imported and have been traced to their botanical 

 source ; but there are others, of more occasional occurrence, the origin 

 of which has not been ascertained.^ 



1. Light, Fusiformii, or Woody Jalap, Male Jcdap, Orizaba Root, 

 Jalap Tops or Stalks, Purgo macho of the Mexicans. 



This drug is derived from Iportioea orizabensis Ledanois,^ a plant of 

 Orizaba, which is but imperfectly known. It is described as a pubescent 

 climber, having a spindle-shaped root about two feet long of woody 

 and fibi'ous texture. The druor occurs in irregular rectano;iilar or block- 

 like pieces, evidently portions of a very large root, divided transversely 

 and longitudinally. Sometimes it is more like true jalap, being in entire 

 roots, of smaller size, spindle-shaped, not spherical. It has a somewhat 

 lighter colour than jalap, and much deeper longitudinal wrinkles. The 

 larger pieces often exhibit deep cuts from an axe or knife ; transverse 

 slices are of rare occurrence. Although generally less ponderous than 

 jaiap, the Orizaba drug is nevertheless of a compact and often horny 

 texture. From jalap it is easily distinguished by its radiated transverse 

 section, and the numerous thick bundles of vessels which project as 

 woody fibres from the fractured surface. 



^ For information about some of these, ^ Journ. de Chimie mid. x. (1834) 1-22. 



consult Guibourt, Histoire des Drogues, ii. pi. 1. 2, (with unsatisfactory figures). 

 (1869) 523. 



