140 



roo c.c. of boiling alcohol dissolve cri grm. The following salts 

 are crystalline: C 10 H 6 O 3 NK + 2H 2 O, (C 10 H 6 O 3 N) 2 Ba + 4*H 2 O, 

 (C 10 H 6 O 3 N) 2 Ca + 2H 2 O and (C 10 H 6 O 3 N) 2 Cu + 2H 2 O. The barium 

 salt is fairly soluble in hot water, but the copper salt is almost in- 

 soluble in it. The crystalline hydrochloride QoHjOgN, HC1 easily 

 loses hydrochloric acid (Brieger [1879]); the basic properties of the 

 substance are further evident from its precipitation by phosphotungstic 

 acid (Hofmeister [1880, Ch. V, creatine]). 



Kynurine, formed in a 90 per cent, yield by heating kynurenic 

 acid to 253-258, is little soluble in cold water, more so in alcohol. 

 The hydrated substance C 9 H 7 ON, 3H 2 O melts at about 52, the anhy- 

 drous substance at 202. It is a feeble base yielding a platinichloride 

 (C 9 H 8 ON) 2 PtCl 6 + 2H 2 O and a crystalline hydrochloride ; with bro- 

 mine the substance C 9 H 4 Br 3 ON is formed (Brieger [1879]). 



Jafffs reaction for kynurenic acid '[1883]. A solution of the acid 

 is evaporated on the water bath with hydrochloric acid and potassium 

 chlorate ; the red residue becomes brownish green with ammonia, soon 

 changing to an intense emerald green ; the chief product is tetrachloro- 

 oxykynurine, C 9 H 3 O 2 NC1 4 . 



A convenient method of estimation has been described by Capaldi 

 [1897,2]. 



