208 THE PRODUCTS OF ALBUMINOUS DIGESTION. 



(1) CH 2 .(NH 2 ).COOH + C 6 H 5 .COC1 s= CH 2 .NH(C 6 H 5 .CO).COOH + HC1 



Glycocoll. Benzoyl chloride. Hippuric acid. 



(2) CH 2 .NH(C 6 H 5 ,CO).COOH 4- C fi H 5 COH = C 6 H 5 .CO.N.C:CH.C 6 H 6 + 2H 2 O 



Hippuric acid. Benzaldehyde. | / 



CO 

 Lactimide. 



(3) C,H 5 .CO.N.C:CH.C 6 H 6 C 6 H 5 .CONH 2 C-COOH 



y + H 2 o = ii 



CO CH.C 6 H 5 



Lactimide. Benzyol-amino-cinnamic acid. 



(4) C 6 H 5 .CONH 2 C COOH 



|| + H 2 = C fi H 5 CO.NH 2 + C 6 H 5 .CH 2 .CO.COOH 

 CH. C 6 H 5 Benzamide. Phenyl-pyro-racemic 



Benzyol-amino-cinnamic acid, 



acid. 



Method. The decomposition of the albumins (gelatin) is effected 

 by prolonged boiling with dilute sulphuric acid 25 per cent, solution. 

 The excess of acid is removed with plumbic carbonate. The filtrate 

 is concentrated, freed from any tyrosin that may have separated out, 

 and then benzoylated with benzoyl chloride in the presence of 

 sodium hydrate. Care should be had that the reaction of the solu- 

 tion is constantly alkaline during this process. The hippuric acid 

 is then extracted with acetic ether. The dried substance is now 

 treated with three molecules of acetic anhydride, one molecule of 

 sodium acetate, and one molecule of benzaldehyde. The mixture is 

 heated on a water-bath for half an hour. The condensation-product 

 is then treated with water and gently warmed. The oil that sepa- 

 rates out is dissolved in hot alcohol and allowed to cool. The lacti- 

 mide then crystallizes out, and can be recognized as follows : the 

 substance is heated with a strong solution of sodium hydrate 

 until a distinct odor of ammonia is noticed. This is due to 

 the decomposition of the benzamide. On acidifying the solution 

 the phenyl-pyro-racemic acid separates out and can be readily ex- 

 tracted by shaking with ether. One portion of the ethereal extract 

 is treated with a dilute solution of the sesquichloride of iron, when 

 on agitation the watery layer assumes a dark-green color, which 

 gradually changes to a characteristic yellow. The other portion is 

 treated with an ethereal solution of phenylhydrazin, which leads to the 

 separation of the hydrazon of phenyl-pyro-racemic acid. After wash- 

 ing with ether this may be identified by its melting-point 161 C. 



As regards the general properties of glycocoll and its preparation 

 as such, see pages 87 and 278). 



Tryptophan. This substance is apparently always formed when 

 the tryptic digestion of the albumins has extended beyond the forma- 

 tion of albumoses. As its presence among the various digestive 

 products is easily recognized, it is thus possible to ascertain whether 

 the destruction of the albuminous molecule has extended to the 

 formation of amino-acids, without testing for these directly. Like 

 the amino-acids, it is also formed during the hydrolytic decomposi- 

 tion of the albumins with baryta-water, and likewise results during 



