312 BACTERIAL POISONS. 



This reaction is identical with that of adenine, whereby 

 hypoxanthine is formed (see page 289). By putrefaction in 

 the absence of air it forms xanthine (SCHINDLER). The 

 change can be represented by the equation : 



C 5 H 5 N 5 + H 2 = C S H 4 N 4 2 + NH 



3 . 



On oxidation with potassium permanganate it yields urea, 

 oxalic acid, and oxy-guanine. By hydrochloric acid and 

 potassium chlorate it is oxidized to carbonic acid, guani- 

 dine, and parabanic acid, according to the equation : 



CO-NH HX 



C 5 H 5 N 5 + H 2 -f 30 = | y CO + g$\ C = NH + CO 2 . 



PARABANIC ACID. GUANIDINE. 



According to STRECKER, a small amount of xanthine is 

 formed in this reaction, and it is quite possible that this 

 base is also formed on oxidation with nitric acid. 



Guanine combines with acids, bases, and salts. It unites 

 with bases to form crystalline compounds ; and with one or 

 two equivalents of acid it also yields crystallizable salts. 

 Thus, with hydrochloric acid it forms the two salts, 

 C 5 H 5 N S O.(HC1) 2 and C 5 H 5 N,O.HC1 + H 2 O. Similar com- 

 binations can be obtained with nitric acid. The sulphate 

 (C 5 H 5 N 5 O) 2 H 2 SO 4 , crystallizes in long needles, and, like 

 the other salts, is decomposable by water. The plat'no- 

 chloride, (C 8 H,N s O.HCl) | PtCl 4 + 2H 2 0, is readily obtained 

 in a crystalline condition. The silver compound is 

 soluble in hot nitric acid, and on cooling recrystallizes 

 in fine, needle-shaped crystals, having the composition 

 C 5 H 5 N 6 O.AgN0 3 . 



The solutions of the hydrochloride are precipitated by 

 mercuric chloride and nitrate, potassium chromate, potas- 

 sium ferricyanide, and by picric acid. Basic lead acetate 

 gives a precipitate only on addition of ammonium hydrate. 

 The reaction with picric acid (CAPRANICA) is said to be 

 very characteristic, and a means of distinguishing this base 

 from xanthine and hypoxanthine. It is best obtained by 

 adding a cold, saturated solution of picric acid to the warm 



