bbieger's method. 161 



Dragendoeff's Method. — The finely divided sub- 

 stance is digested for some liours 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. This 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 

 Avith 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 ex- 

 tractions : 



(1) The acid liquid is shaken with freshly rectified petro- 

 leum ether as long as this reagent leaves any residue on 

 evaporation. 



(2) The acid fluid is now extracted with benzine. 



(3) The next solvent used is chloroform. 



(4) The liquid is now again extracted with petroleum 

 ether in order to remove traces of benzine and chloroform . 



(5) The liquid is now made alkalioe with ammonia and 

 successively extracted with petroleum ether, benzine, chloro- 

 form, and amylic alcohol. 



(6) The remainder of the ammoniacal liquid is mixed 

 with powdered glass, evaporated to dryness, the residue 

 pulverized, and extracted with chloroform. 



The residue obtained with each of the above solvents 

 should be examined for ptomaines. 



Bbieger's Method. — The substance under examination 

 is divided as finely as possible, aud then heated with water 

 slightly acidified with hydrochloric acid. During the 

 heating care must be taken that the feebly acid reaction is 

 maintained. The heating should continue for only a few 

 minutes. The liquid is then filtered aud concentrated, at 

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

 one has material which is highly odorous, as is the case 

 frequently both with aqueous and alcoholic extracts of 

 putrid material, Beiegbr recommends that a piece of 

 apparatus devised by Bocklisch be used. The fluid to be 

 evaporated is placed in a globular flask, the rubber stopper 



