CHAPTER IX. 



ANALYSIS OF THE PRODUCTS OF ALBUMINOUS DIGESTION. 



To demonstrate the formation of the various products of albu- 

 minous digestion and to separate the individual substances from each 

 other, the following plan of work may be adopted : 



THE PRODUCTS OF PEPTIC DIGESTION. 



One hundred grammes of moist fibrin that has been thoroughly 

 washed in running water are placed in 1000 c.c. of an 0.3 per cent, 

 solution of hydrochloric acid, to which a few grammes of pepsin 

 have been added. The mixture is kept at a temperature of 40 C., 

 and may be examined for the primary products of digestion after 

 about two hours, while the secondary products can only be demon- 

 strated after a longer period of time. From time to time it is 

 then necessary to ascertain whether free hydrochloric acid is still 

 present, and to add an additional amount whenever it is wanting, 

 so that the acidity referable to free acid remains about the same 

 during the entire period of digestion. The occasional addition of 

 a little pepsin is also advisable. The first specimen for examina- 

 tion is taken after two hours. The liquid is filtered and neutral- 

 ized with a dilute solution of sodium hydrate. The precipitate 

 which thus forms consists of syntoniii and is filtered off. The fil- 

 trate is rendered feebly acid with very dilute acetic acid, treated 

 with an equal volume of a saturated solution of common salt, and 

 boiled. Any native coagulable albumin that may be present is 

 thus precipitated and is filtered off on cooling. The solution is 

 again made neutral and treated with an equal volume of a satu- 

 rated solution of -ammonium sulphate. In this manner the primary 

 albumoses of Kiihne are precipitated, and are filtered off after stand- 

 ing for about one-half hour. To separate the proto-albumose from 

 the hetero-albumose, the precipitate is dissolved in hot water and 

 treated with an equal volume of 95 per cent, alcohol. On standing, 

 the hetero-albumose separates out, while the proto-albumose is found 

 in the alcoholic filtrate. It is purified by repeated solution in hot 

 water and precipitation with alcohol. To isolate the proto-albumose, 

 the alcoholic filtrate is evaporated to dryness on a water-bath, or the 

 alcohol is distilled off in the vacuum. The remaining material is 

 repeatedly dissolved in water and treated with alcohol until the 

 alcoholic solution remains clear on standing. To this end, it is 

 usually necessary to repeat the solution in water and the treatment 

 with alcohol five or six times. 



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