184 ALKALOIDS. 



! 



brucine salt from ?/ = 7'1733 (m-0'01852 xc), c being the same 

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

 mixed hydrochlorates. 



Titration of mwphine and narcotine with potassio-mercuric iodide 

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

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

 estimated volumetrically with that reagent. 



For a method of examining ckelidonium compare 65 and my 

 ' Werthbestimmung,' p. 98. 



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

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

 with this reagent than compare the extracts of two or more 

 different samples of seeds with one another. 1 If an approximate 

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

 that, according to the investigations of Weigelin, 2 all three are re- 

 moved together by shaking with chloroform ; that sabadilline is 

 almost insoluble in ether, but is dissolved by 150 parts of Avater 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 Harnack and "Witkowski have proved 3 

 that the calabar lean also contains two alkaloids (calabarine and 

 physostigmine), differing from one another in physiological action. 

 For this reason the 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. Ooniine, pilocarpine, etc. Zinoffsky has shown that 

 coniine can be accurately estimated by phosphomolybdic acid in 

 solutions free from ammoniacal salts. 4 The strength of the 

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



1 Compare E. Masing, Archiv d. Pharm. [3], ix. 310, 1876 (Journ. Chem. 

 Soc. xxxii. 367). 



2 Compare Weigelin, '"[Inters, iiber die Alkalo'ide der Sabadillsamen, ' Diss. 

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

 4 Beitr. z. gerichtl. chem. Nachw. des Strychn ins u. Veratrins,' Diss. Dorpat, 

 1868. 



3 Compare Archiv f. exper. Patholog. und Pharmacol, v. 401, 1876 (Pharm. 

 Journ. and Trans. [3], viii. 3). 



4 ' Die quant. Best. d. Emetins, Aconitins und Xicotins,' Diss. Dorpat, 

 1872 (Pharm. Journ. and Trans. [3], iv. 442). 



