200 ALKALOIDS. 



and allowed to stand exposed to the air, with occasional agitation, 

 until the, excess, of ammonia has disappeared (not longer). The 

 precipitated mixture of morphine, narcotine, and meconate of 

 calcTuin is filtered off aadi dried. It should amount to not less 

 thaa 14 per cent, of the opium used. Filtrate and washings are 

 treated according to V. 



in. The precipitate is removed from the filter, reduced to the 

 finest possible powder, and macerated ydih. pure ether in, a, dry 

 flask as long as narcotine is removed. The ethereal solutions ate 

 filtered through the same filter, evaporated to dryness at 110°, 

 and weighed, or instead of weighing the residue may be dissolved 

 in water acidulated with sulphuric acid, and titrated with potassio- 

 mercuric iodide (§ 65). The' weight is noted as the amount of 

 narcotine soluble in water. 



rV. Theresidue insoluble in ether is dried and exhausted with 

 boiling alcohol of specific gravity 0-81, which removes morphine, 

 and leaves meconate of calcium undissolved. The alcoholic solu- 

 tions are filtered through the filter already used in the extraction 

 with ether. The weight of the alkaloid can be ascertained either 

 by evaporating to dryness, redissolving in acidulated water, pre- 

 cipitating with ammonia,-and weighing, or by evaporating, redis- 

 solving in dilute sulphuric acid, and titrating according to § 65. 

 Good opium contains at least 8 per cent, of morphine. 



V. If the morphine is reprecipitated for gravimetric estimation 

 the filtrate may be mixed with the filtrate from II., made alkaline 

 with ammonia, and shaken with amylic alcohol. AH the morphine 

 in solution is thus removed, and the amount which escapes precipi- 

 tation in II. is sometimes very considerable. The amylic-alcohol 

 solutions are , evaporated to dryness, the residue dissolved in a 

 little acidulated water, precipitated with a slight excess of 

 ammonia, dried, weighed, and noted as morphine. A correction 

 of O'OOl gram for each ce. of mother-liquid may be made if 

 desirable. 



VI. If the sample under examination is an opium of good 

 quality the insoluble residue from I. wiU contain narcotine, but 

 no morphine; The former may be estimated by extracting with 

 water acidulated with sulphuric acid, precipitating with ammonia, 

 filtering, washing, redissolving in dilute sulphuric acid, and 

 titrating with potassio-mercu"ic iodide (§ 65). 



§ 188. Other Methods. — Weak spirit was also formerly employed 



