MUSCULAR TISSUE 



351 



By this means hypoxanthine nitrate has been formed and is present in the filtrate. 

 (For crystalline form of hypoxanthine nitrate see Fig. 40, p. 136.) Concentrate 

 on a water-bath to drive off hydrogen sulphide, and render the solution slightly 

 alkaline with ammonia. Warm for a time, to remove the free ammonia, filter, 



FIG. 112. HYPOXANTHINE SILVER NITRATE. 

 (Drawn from a student preparation by Dr. E. F. Hirsch.) 



concentrate the filtrate to a small volume and allow it to stand in a cool place. 

 Hypoxanthine should crystallize in small colorless needles. Examine the 

 crystals under the microscope. 



3. Xanthine. To the filtrate from the above experiment containing the 



FIG. 113. XANTHINE SILVER NITRATE. 



xanthine silver nitrate add ammonia in excess. (The crystalline form of xan- 

 thine silver nitrate is shown in Fig. 113.) A brownish-red precipitate of 

 xanthine silver forms. Treat this suspended precipitate with hydrogen sulphide 

 (do not use an excess of hydrogen sulphide), warm the mixture for a few mo- 



