232 



METHODS OF EXTRACTING PTOMAINS. 



Chloroform, amylic alcohol, and benzene are used as solvents after 

 extraction with ether. 



Dragendorffs Method. — The finely divided substance is digested 

 for some hours with water acidulated with sulphuric acid, at from 

 40° to 50°. This is repeated two or three times, and the united 

 filtered extracts are evaporated to a syrup, which is treated with 

 four volumes of alcohol and digested for twenty-four hours at 30°. 

 After cooling, the alcoholic extract is filtered, the residue washed 

 with 70 per cent, alcohol, and the united filtrates freed from alcohol 

 by distillation. The aqueous residue, diluted if desirable, is filtered 

 and submitted to the following extractions : 



1. The acid liquid is shaken with freshly rectified petroleum ether, 

 as long as this reagent leaves a residue on evaporation. 



2. The acid fluid is now extracted with benzene. 



3. The next solvent used is chloroform. 



4. The liquid is now again extracted with petroleum ether in order 

 to remove traces of benzene and chloroform. 



5. The liquid is next made alkaline with ammonia and succes- 

 sively extracted with petroleum ether, benzene, chloroform, and amy- 

 lic alcohol. 



6. The remainder of the ammoniacal liquid is mixed with pow- 

 dered glass, evaporated to dryness, the residue pulverized, and ex- 

 tracted with chloroform. 



The residue obtained with each of the above solvents should be 

 examined for ptomains. 



Brieger's Method. — The substance under examination is divided 

 as finely as possible, and then heated with water slightly acidified 

 with hydrochloric acid. During the heating care must be taken that 

 the feebly acid reaction is maintained, and the 

 heat should continue for only a few minutes. 

 The liquid is then filtered and concentrated, at 

 first on a plate and then on the water-bath, to 

 a syrup. If one has highly odorous material, a 

 piece of apparatus devised by Bocklisch is of 

 service. The fluid to be evaporated is placed in 

 a globular flask, the rubber stopper of which 

 carries two small glass tubes, one of which, B, 

 extends to the bottom of the flask, while A is 

 connected with a water-pump or aspirator, which 

 draws the vapor through the tube. In order to 

 prevent the return of condensed fluids, the end 

 of A in the flask is curved on itself. The tube B 

 is finely drawn out and through it a current 

 of air is constantly moving and prevents the 



Fig. 2. 



