186 EXOGONIUM PURGA 



whole year ; but principally in the spring when the young shoots 

 begin to appear. The roots (tubercules) are then placed in nets, 

 and dried by the aid of fire heat. The smaller tubercules are 

 dried entire ; but the larger ones are more or less incised to 

 facilitate desiccation, or cut into halves or quarters, or rarely into 

 transverse slices, for the same purpose. 



Jalap is imported from Vera Cruz, and the average imports 

 into the United Kingdom may be estimated at about 180,000 Ibs. 



General Characters and Composition. When entire, the tuber- 

 cules are usually irregularly roundish or somewhat ovoid, rarely 

 they are fusiform or even cylindrical ; they vary commonly in 

 size from a hazel-nut to that of a hen's egg, but sometimes 

 they are as large as a man's fist, or even larger. The large 

 tubercules are generally marked with the circular or transverse 

 incisions, made as noticed above, to facilitate their drying. 

 Externally they have a dark brown colour, and are more or less 

 deeply furrowed, contorted, and wrinkled, or rarely they are 

 nearly smooth. Internally their colour is dirty yellowish or 

 brownish, and marked frequently with darker brown irregularly 

 concentric rings. They have a faint, peculiar, somewhat nauseous 

 odour, which is increased by rubbing or powdering them ; and 

 a nauseous, sweetish, subsequently acrid taste. Good jalap is 

 hard, heavy, plump, and resinous ; the light, whitish, amylaceous, 

 shrivelled, or woody pieces, are of inferior quality. The powder 

 of jalap is of a yellowish-grey colour. 



The activity of jalap is due to a resin, which is official in the 

 British Pharmacopoeia and in the Pharmacopoeias of India and the 

 United States.. The amount of resin has been variously estimated 

 at from 11 to 21 per cent. Among other constituents of jalap, 

 are sugar, starch, gum, and colouring matter. From this crude 

 resin which is obtained from jalap by spirit of wine, two resins 

 may be extracted, one which is soluble in ether, and which consti- 

 tutes from 5 to 8 per cent, of its substance, or, according to 

 Umney, 12 per cent. ; and another forming the residue, which is 

 insoluble in ether, and which has been termed Convolvulin, or 

 formerly by Pereira Jalapin, but this latter name, as will be presently 



