184 ALKALOIDS. 



brucine salt from ^ = 7*1 733 (m - 01852 x c), c being the same 

 as in the previous expressions and m denoting the weight of the 

 mijxed hydrochlorates. 



Titration of morphine and narcotime witK potassio-mercuric iodide 

 serves only as a check on the weight of the alkaloids after 

 isolation (§§ 182, 187). The total alkaloid in opium cannot he 

 estimated volumetrically with that reagent. 



For a method of examining chelidonium compare § 65 and my 

 ' Werthbestimmung,' p; 98. 



The presence in cevadUla seeds of three alkaloids, all of which 

 act upon potassio-mercuric iodide, renders it impossible to jdo more 

 with this reagent than compare the extracts of two or more 

 difiFerent samples of seeds with one another.-^ If an approximate 

 separation of the three alkaloids is desired, it must be remembered 

 that, according to the investigations of Weigelin,* all three are re- 

 moved together by shaking with chloroform; that sabadilline is 

 almost insoluble in ether, but is dissolved by 150 parts of water at 

 the ordinary temperature ; that sabatrine is freely soluble in ether 

 and soluble in 40 parts of cold water; and finally that veratrine is 

 said to be taken up by 10 parts of ether and 1,000 of cold water. 



The researches of Hamack and Witkowski have proved* 

 that the caMba/r J>ean also contains two alkaloids (calabarine and 

 physostigmine), diflfering from one another in physiological action. 

 For this reason ithe estimation of the total alkaloid by titration 

 with potassio-mercuric iodide has only a limited value, but the 

 ■alkaloids might possibly be separated, and estimated gravimetri- 

 cally, as the calabarine precipitate is insoluble in alcohol whilst that 

 produced by physostigmine is soluble. 



§ 175. Gonime, pilocarpine, efc.-^Zinoffsky has shown that 

 eoniim can be accuriately estimated by phosphomolybdic acid in 

 solutions free from ammoniacal salts.* The strength of the 

 reagent was such that 1 cc. precipitated 0'05 gram of coniine. 



I Compare E. Masing, Archiv d. Pharm. [3], ix. 310, 1876 ( Joum. Ghem. 

 Soo. xxxii. 367). 



'^ Compare 'Weigelm, 'ITntera. fiber die AUcaloide der Sskbadillsamen,' Diaa. 

 Dorpat, 1871 (Journ. Chem. See. xxv. 828). See also P. G. A. Masing, 

 'Beitr. z. gerichtl. chem. Nachw. des Stryehnins u. Veratrins,' Diss. Dorpat, 

 1868. 



* Compare Archiv {. exper. Fatholog. iind PharmacoV-T-. 401, 1876 (Pharm. 

 Jt>um. and Trans. [3], viii. 3) . 



* ' Die quant. Best. d. Bmetins, Aoonitins tmd Kicotina,' Diss. Dorpat, 

 1872 (Pharin. Journ. and Trans. [3], iv. Hi). 



