356 SUBTERRANEAN ORGANS 



and methyl jalapinolate. The resin soluble in ethyl acetate gives 

 similar results. The chief constituents, therefore, appear to be the 

 glucoside and methylpentoside of jalapinolic acid and its methyl 

 ester ; these are very similar to those of scammony resin (see p. 351). 

 The following table shows the solubility of certain Convolvulaceous 

 resins when treated with various solvents in success. 



Mexican Braz. 

 Jalap Scammony Scamm. Jalap purpurea 



Petroleum Spirit . . 1-9 4-5 6-2 2-1 8-0 



Ether .... 9-7 92-5 64-8 5-4 7-3 



Chloroform . . .24-1 0-4 0-6 73-4 9-8 



Ethyl Acetate . . . 22-0 . . 24-8 14-2 23-8 



Alcohol .... 38-8 1-8 2-3 4-7 49-0 



Acid Value ... 15 20 20 



Saponification Value . .140 235 180 



Optical Rotation . . 37 19-8 23 



The therapeutic action of Orizaba jalap resin appears to be very 

 similar to that of scammony resin and although the two resins are 

 not identical the British Pharmacopoeia permits both roots to be used 

 in the preparation of scammony resin. 



Note. Brazilian jalap, which has lately appeared on the market, is the root 

 of Piptostegia Pisonis, Martius (N.O. Convolvulacece). It occurs in the form 

 of transverse, circular slices about 3 to 5 cm. in diameter, and 1 cm. thick, pale 

 greyish brown, with several concentric rings and exhibiting pale resin cells ; 

 it contains 20 per cent, of resin, very little of which is soluble in ether. 



The root of Ipomcea purpurea, Linne (N. America), contains 4-8 per cent, 

 of a purgative resin. 



TURPETH 



(Turpethum, Radix Turpethi) 



Source, &c. The dried root and stem of Ipomosa Turpethum, 

 Robert Brown (N.O. Convolvulaceae) , a native of India, Ceylon, the 

 Malay Archipelago and N. Australia. 



Description. Turpeth occurs in pieces of very varying length and 

 thickness ; they are often 10 to 20 cm. long and 1 to 5 cm. wide, deeply 

 wrinkled longitudinally, and of a dull grey or brown colour ; sometimes 

 the bark has been slit on one side and the central wood removed. 

 Fracture short, the wood in old specimens in several concentric 

 circles ; vessels very large ; medullary rays wide ; in the bark resin 

 cells and frequently abnormal wood bundles. Odour slight, taste 

 nauseous but slowly developed. 



Constituents. Turpeth contains from 5 to 10 per cent, of resin, 

 part of which is soluble and part insoluble in ether. The ether- 

 soluble resin is a mixture of a- and /3-turpethein, the ether-insoluble 



