HYPOXANTHINE AND ADENINE. 187 



and carp. Hypoxan thine occurs also in the marrow and in very small 

 quantities in normal urine, and, as it seems, also in milk. It is found 

 in rather considerable quantities in the blood and urine in leucaemia. 



Hypoxanthine forms very small, colorless, crystalline needles. It 

 dissolves with difficulty in cold water, but the claims concerning 

 solubility therein are very contradictory. 1 It dissolves more readily 

 in boiling water, in about 70-80 parts. It is nearly insoluble in alcohol, 

 but is dissolved by acids and alkalies. The compound with hydrochloric 

 acid is crystalline, and is more soluble than the corresponding xanthine 

 derivative. It is easily soluble in dilute alkalies and ammonia. The 

 silver compound dissolves with difficulty in boiling nitric acid. On 

 cooling, a mixture of two hypoxanthine silver-nitrate compounds possess- 

 ing an inconstant composition separates out. On treating this mixture 

 with ammonia and an excess of silver-nitrate and heating, a silver hypo- 

 xanthine is formed, which when dried at 120 C. has a constant com- 

 position, 2(C5H 2 Ag2N 4 O)H2O, and is used in the quantitative estima- 

 tion of hypoxanthine. Hypoxanthine picrate is soluble with difficulty, 

 but if a boiling-hot solution of it is treated with a neutral or only 

 faintly acid solution of silver nitrate the hypoxanthine is nearly quan- 

 titatively precipitated as the compound CsHsAgN^.CeH^N^^OH. 

 Hypoxanthine does not yield an insoluble compound with metaphosphoric 

 acid. When treated, like xanthine, with nitric acid, it yields a nearly 

 colorless residue which, on warming with alkali, does not turn red. Hypo- 

 xanthine does not give WEIDEL'S reaction. After the action of hydro- 

 chloric acid and zinc a hypoxanthine solution becomes first ruby-red 

 and then brownish red in color on the addition of an excess of alkali 

 (KOSSEL). According to E. FISCHER 2 a red coloration occurs even in 

 the acid solution. 



N=C.NH 2 



Adenine, CjHsNs, = HC C NH X (6-aminopurine) , was first found 



H 



!UU 



by KOSSEL 3 in the pancreas. It occurs in all nucleated cells, but in 

 greatest quantities in the sperm of the carp and in the thymus. Adenine 

 has also been found in lucaemic urine (STADTHAGEN 4 ). It may be obtained 

 in large quantities from tea-leaves. 



Adenine crystallizes with 3 molecules of water of crystallization in 

 long needles which gradually become opaque in the air, but much more 



1 See E. Fischer, Ber. d. deutsch. chem. Gesellsch., 30. 



2 Kossel, Zeitschr. f. physiol. Chem., 12, 252; E. Fischer, 1. c. 



3 See Zeitschr. f . physiol. Chem., 10 and 12. 



4 Virchow's Arch., 109. 



