190 ALKALOIDS. 



Supposing, then, both these alkaloids to have been extracted 

 together by shaking with chloroform, and to have been redis- 

 solved in dilute (2 per cent.) acetic acid, the addition of dilute 

 sulphuric acid to such a solution "would cause the precipitation of 

 the majority of the jervine as sparingly soluble acid sulphate 

 (Simon's vegetable baryta). According to Bullock this salt 

 requires 427 parts of cold water for solution, and the precipitate 

 contains 15-5 per cent, of sulphuric acid (H^SO^). The hydro- 

 chloric acid precij^tate (6 'So per cent. HCl) is more soluble; the 

 most advantageous method of all is to precipitate nitrate of jervine 

 (soluble in 1,200 parts of cold water) b}' adding nitrate of 

 potassium to acetic acid solution. Yeratroidine remains in the 

 filtrate, from which it can be extracted by shaking with chloro- 

 form. In a similar manner j)r(?7'c//;e may be separated from other 

 cinchona alkaloids in the form of a sparingly soluble nitrate. 



The behaviour of two alkaloids to bases will more frequently be 

 found to present differences, of which advantage may be taken. 

 Here two cases are to be distinguished : viz., either one alkaloid 

 is precipitated, and the other left in solution ; or, both are pre- 

 cipitated, but one is redissolved by an excess of the precipitant, 

 whilst the other is not. As an instance of the first of these two 

 cases, the separation of Tiarcotine from narceine may be cited ; the 

 former is almost completely precipitated by ammonia, whereas the 

 narceine remains in solution. MorjyJiine and codeine serve to 

 exemplify the second case, which is of more frequent occurrence ; 

 excess of ammonia precipitates the former tolerably comi)letely, 

 but the codeine remains dissolved in the filtrate, from which it 

 may be extracted by shaking with benzene. On the other hand, 

 an excess of lime-water causes the separation of narcotine, but 

 does not precipitate morphine. But nearly the Avhole of the 

 latter alkaloid is thrown down if chloride of ammonium be added 

 to the solution in caustic lime (§ 187). 



This method of precijjitation with excess of alkali is, however, 

 unreliable in some cases, in Avhich favourable results might have 

 been anticipated. Strychnine can be separated from an acid 

 solution very satisfactorily by the addition of excess of ammonia ; 

 brucine under the same conditions remains in solution until the 

 gi-eater part of the ammonia has volatilized. But if both alkaloids 

 are present together, part of the brucine will separate with the 

 strychnine on the addition of ammonia.^ 



^ Sec my 'Ermittelung von Giften,' 2nd edition, 259. 



