66 NUCLEOPROTEINS, NUCLEINS, NUCLEIC ACIDS. [CH. III. 



cooling the solution deposits needle clusters of guanine chloride, 

 C 5 H 6 N 5 O.HC1.2H.jO. The filtrate A is filtered again if necessary, 

 and made faintly acid with 20 per cent, sulphuric acid. Boil and 

 add 10 per cent, copper sulphate. The adenine cuprous compound is 

 precipitated. Filter and wash. Suspend in water and decompose 

 by sulphuretted hydrogen. Filter from copper sulphide and 

 evaporate to dryness on the water bath. Dissolve in the smallest 

 possible amount of hot 5 per cent, sulphuric acid, and allow to cool. 

 Adenine sulphate (C 5 H 5 N 5 ) 2 H 2 S0 4 .2H 2 O is obtained in crystalline 

 form. 



