66 LABORATORY WORK L\ PHYSIOLOGICAL CHEMISTRY. 



Crystalline Precipitate. 

 See Leucine and Tyrosine. 



Filtrate B. 



See Proteoses and "Peptones." 



Tryptophane, indoleaminopropionic acid (proteinochro- 

 mogen). This substance is formed as one of the products in 

 the pronounced cleavage of proteins as in tryptic digestion 

 and putrefaction. Its presence in the protein molecule is of 

 considerable importance to the animal economy. It is sup- 

 posed to stand as the mother substance of the various pig- 

 ments of the body. Add a few c.c. of chlorine or bromine 

 water to the solution; a reddish-violet precipitate results 

 (proteinochrome). 



Finally examine the mercuric cyanide valve which was 

 attached to the flask containing the putrefactive mixture. 



Hydrogen sulphide has produced a black precipitate of 

 HgS. 



Methyl mercaptan is indicated by the presence of a gray- 

 ish-green precipitate. 



