ALKALOIDS. 603 



analysis in case legal proceedings depend on the result of the 

 chemist's report. 



Of the various methods applied for the separation of alkaloids from organic 

 matter, the following may be mentioned : 



The substance to be examined is properly comminuted (if this be necessary) 

 and repeatedly digested at 40 to 50 C. (104 to 122 F.) with water slightly 

 acidulated with sulphuric acid. The filtered liquids (containing the sulphates 

 of the alkaloids) are evaporated over a water-bath to a thin syrup, which is 

 mixed with three or four times its own volume of alcohol ; this mixture is 

 digested at about 35 C. (95 F.) for several hours, cooled, filtered, and again 

 evaporated nearly to dryness. (By this treatment with alcohol many substances 

 soluble in the acidified water, but insoluble in diluted alcohol, are eliminated 

 and left on the filter, while the alkaloids remain in solution as sulphates.) 



A little water is now added to the residue, and this solution, which should yet 

 have a slight acid reaction, is shaken with about three times its own volume of 

 acetic ether, which dissolves some coloring and extractive matters, but does not 

 act upon the alkaloid salts. The two strata of liquids which form on standing 

 in a tube are separated by means of a pipette, and the operation is repeated, if 

 necessary, i. e., if the ether should have been strongly colored - 



The remaining acid aqueous solution is next slightly supersaturated with 

 sodium carbonate, which liberates the alkaloids. Upon now shaking the solu- 

 tion with acetic ether, all alkaloids are dissolved in this liquid, which, after 

 being separated from the aqueous solution, leaves upon evaporation, at a low 

 temperature, the alkaloids generally in a sufficiently pure state for recognition 

 by special tests. It may, however, be necessary to purify the residue further 

 by neutralizing with an acid, allowing to crystallize in a watch-glass, and sep- 

 arating the small crystals from adhering mother-liquor. 



The above method for detecting alkaloids in the presence of organic matter 

 generally answers the requirements of students. 



The practical toxicologist has in most cases of poisoning some data (deduced 

 from the symptoms before death, or from the results of the post-mortem exam- 

 ination) pointing to a certain poison, which, of course, facilitate his work con- 

 siderably. 



Classificati9n of alkaloids. While the constitution of many alka- 

 loids has as yet not been determined, others have been shown to be 

 derivatives, or to contain the nuclei of either pyridine, quinoline, or 

 isoquinoline. Closely related to pyridine are the liquid bases coniine, 

 nicotine, and sparteine, as also the solid alkaloids atropine, cocaine, 

 ecgonine, and others. Among alkaloids derived from quinoline are 

 those found in cinchona bark and in nux vomica. Related to iso- 

 quinoline are the opium alkaloids. 



The pyridine group of alkaloids. 



The close relationship between pyridine and some of the vegetable 

 alkaloids may be shown by considering their structure, which is this : 



