60 SUBSTANCES SOLUBLE IN ALCOHOL. 



tioned, and will only remark here tJiat, as a rule, the material 

 may be extracted with water acidulated with sulphuric acid, and 

 that in many cases the estimation may be made in this liquid 

 without further treatment. But if the presence of mucilaginous 

 substances, etc., prevent this, and their partial removal by alcohol 

 be necessary, the solution must be completely freed from spirit 

 before titrating. The termination of the reaction is usually found 

 by a drop of the filtered solution yielding no precipitate with a 

 drop of the reagent. 



Aconitine and Nepaline. — 1 cc. of potassio-mercuric iodide 

 solution of the above strength indicates 0'0269 gram of aconitine, 

 and the priscipitate (if the estimation be made gravimetrically) 

 has the composition Cj^H^jNOjoI^ + Hglyi In the latter case 

 a correction of 0-00005 gram of aconitine must be made for every 

 cc. of solution. 



1 cc. of potass Jo-mercuric iodide indicates 0388 gram nepaline 

 (pseudaconitine). 



Atropine. — 1 cc. is equivalent to 0'0097 gram atropine if the 

 solution contain about 1 in 200, but in solutions containing 

 1 in 330 it is equivalent to only 0-00829 gram. The preci- 

 pitate obtained by adding an excess of the precipitant to a 

 solution containing about 1 in 200 to 300 has the composition 

 (CiyH24^K03l)2 + Hgl2. In working with solutions containing 

 1 in about 350 to 600 a correction must be made of '00005 gram 

 of atropine for every cc. of filtrate (§ 174)^ 



Hyoscyamine. — 1 cc. of the mercury soliition is equivalent to 

 0-00698 gram hyoscyamine, the concentration being about 1 in 

 200. According to the more recent researches of Ladenburg 

 henbane contains two alkaloids, one of which is isomeric with 

 atropine, and identical with daturine and duboisine. Compare 

 Berichte d. d. chem. Ges. xiii. 909, 1081, 1340, 1549 (Pharm. 

 Journ. and Trans., [3], x. 759, 789, 790). [Ladenburg distin- 

 guishes hyoscyamine from atropine by the melting-points of the 

 alkaloids and their gold salts. In belladonna a second alkaloid 

 at least is present, which is possibly identical with hyoscyamine.^ 

 The second alkaloid in henbane has been named hyoscine by 

 Ladenburg. This must not, however, be confounded with 



^ for the present I make use of the old formula for aconitine, as the new 

 does not agree so well with the voUunetric determinations. 

 " Compare Kraut, Ber. d. d, chem. GJes. xiii. 165. 



