§ 154. ESTIMATION OF SANTONIN. 141 



the amvolvuliH of true jalap, -which ia distinguished by its insolu- 

 bility in ether, and of iurpethm,^ which is insoluble in ether, but 

 differs in composition from convolvulin. 



All these glucosidal resins dissolve in cone, sulphuric acid with 

 purple colour. 



§ 154. Estimation of Saiitionin.—"[h.e following method may be 

 adopted for the quantitative estimation of santonin (§ 45) in 

 worm-seed :'- 



15 to 20 grams of the material are digested on a -water-bath for 

 2 hours -with 15 to 20 cc. of a 10 per cent, caustic soda solution 

 diluted with about 200 cc. of water, filtered and washed. The 

 filtrate and washings are concentrated to 30 or 40 cc, cooled; 

 neutralized with hydrochloric acid, and at once filtered. The pre- 

 cipitate is washed first -with 15 to 20 cc. of water, and then with 

 an 8 per cent, soda solution, and any crystals of santonin 

 that may thus be separated subsequently added to the principal 

 portion. The filtrate from the hydrochloric acid precipitate is 

 acidified and shaken with 3 successive portions (if 1,0 to 20 cc. of 

 chlorofoiin. The chloroformio solutions are washed with water 

 and evaporated to dryness ; the residue is dissolved in the smallest 

 possible quantity of soda, filtered if necessary (washing the in- 

 soluble portion with a very little water), and acidified -with 

 hydrochloric acid. After standing for 2 or 3 days in a cool 

 place the santonin is filtered off, washed with 10 to 15 cc. of 

 8 per cent, solution of soda, dried at 110°, and weighed. A cor- 

 rection must be made of 0-002 gram for every 10. cc. of mother- 

 liquor, and 0'003 gram for every 10 cc. of washings. 



Santonin can also be extracted by boiling viith milk of lime. 

 15 to 20 gTams of worm-seed are digested with 200 cc. of milk of 

 lime diluted with 40,0 cc. of water on the water-bath for 6 hours, 

 boiled for half an hour and filtered. The residue is again boiled 

 ■with 10 cc. of milk of lime diluted with 200 cc. of water. The 

 filtered decoctions and washings are evaporated to about 30 cc, 

 excess of hydrochloric acid added, and at once filtered (the preci- 

 pitate being treated with soda as before). The filtrate must 

 stand for 5' or 6 days in a cool place, when the santonin may be 

 collected and washed with soda-sblution. The sinall amount that 



' N. Repert. f. Pliarm. xiii. 97, 1864 (Amer. Journ. Pharm. xxxi. 374). 

 s Compare Archiv d. Pharm. [«], xiii. 306, 1878 (Amer, Journ. PJiarm. I. 

 296). 



