ALKALOIDS. 321 



Non-volatile alkaloids are precipitated from the acid solution 

 by the addition of an alkali, and the impure alkaloid thus 

 obtained is purified by again dissolving in an acid and repre- 

 cipitating, or by dissolving in alcohol and evaporating the 

 solution. 



Antidotes. In cases of poisoning by alkaloids the stomach- 

 pump and emetics (zinc sulphate) should be applied as soon as 

 possible ; astringent liquids may be given, because tannic acid 

 forms insoluble compounds with most of the alkaloids. In 

 some cases special physiological antidotes exist, and should be 

 used. 



Detection of alkaloids in cases of poisoning. The separation 

 and detection of poisonous alkaloids in organic matter (food, 

 contents of stomach, etc.), especially when present, as is gener- 

 ally the case, in very small quantities, is one of the most difficult 

 tasks of the toxicologist, and none but an expert, who has made 

 himself thoroughly familiar with the methods of discovering 

 minute quantities of organic poisons in the animal system, 

 should undertake to make such an analysis in case legal pro- 

 ceedings depend on the result of the chemist's report. 



Of the various methods applied for the separation of alka- 

 loids 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 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 for several hours, cooled, filtered, and again evaporated 

 nearly to dry ness. (By this treatment with alcohol many sub- 

 stances soluble in the acidified water, but insoluble in diluted 

 alcohol, are eliminated and left on the filter, whilst the alkaloids 

 remain in solution as sulphates.) 



A little water is now added to the residue and the liquid 

 supersaturated with sodium carbonate, which decomposes the 

 salts of the alkaloids, liberating the latter. The mixture is now 

 well shaken with five times its volume of pure ether, which 

 dissolves the poisonous alkaloids, except morphine and strych- 



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