162 PHYSIOLOGICAL AND PATHOLOGICAL CHEMISTRY. 



The distillation residue has an acid reaction. In order to 

 avoid the escape of phenyl-propionic and phenyl-acetic acid 

 with the steam on evaporating, it must be made alkaline 

 with sodium carbonate solution. Since the fluid still con- 

 tains ammonium salts, it must be again made alkaline from 

 time to time. Evaporate to a sirup, precipitate with several 

 times its volume of alcohol, and filter, best not till next day, 

 from the precipitate (B) consisting of undissolved albumin, etc. 



The filtrate (A) is freed from alcohol by evaporating on 

 the water-bath, the residue dissolved in 150 cc. of dilute sul- 

 phuric acid (20 per cent, i.e., 200 g. H 2 S0 4 in the liter), and 

 repeatedly, but not too violently, shaken with ether. The 

 ether frequently settles very slowly, and it is often necessary 

 to add alcohol to facilitate the separation of the ether. 



The aqueous solution (D) remaining contains, besides 

 free sulphuric acid, albumoses and peptone. 



The ether extract (C) is distilled, the residue dissolved in 

 water and sodium hydroxide solution (added to alkaline reac- 

 tion), and, in order to precipitate the palmitic, stearic, and 

 oleic acids, barium chloride solution is added as long as a 

 precipitate forms, and after allowing to stand awhile the 

 liquid is filtered. 



The precipitate (E) consists of barium soaps. 



The filtrate (F) is evaporated to about 100 cc., placed in 

 a separating-funnel, 100 cc. of hydrochloric acid added, and 

 extracted with ether. 



The ether solution (G) is drawn off, distilled, and then 

 evaporated on the water-bath. The oil remaining is washed 

 into a flask with hot water, boiled with about 100 cc. of water, 

 cooled and filtered. 



The aqueous solution (H) contains sodium chloride and 

 hydrochlorides of some organic bases. To isolate these, evapo- 

 rate the solution as completely as possible and extract the 

 residue with absolute alcohol. After allowing to stand for 

 some time, filter the solution and evaporate to dry ness on 



