420 CHEMISTRY OF THE LEUOOMAINS. 



HN— CO NH, HN— GO 



00 COH + CO =00 <>-li_ 



I II f 



IN— O— NH 



DOH + 00 =00 6-NH + 2H,0. 



HN— COH NH, m 



Iso-DiALUBic Acid. Uric Acid. 



Fischer and Ach prepared uric acid from the pyrimidin body 

 pseudo-uric acid. This on fusion with oxalic acid or better on boil- 

 ing with 20 per cent, hydrochloric acid yields uric acid. 

 HN— CO HN— GO 



00 CH.NH.CO.NH, = OC 0—liB. + H,0. 



I Ml f 



HN— CO HN— C— NH 



FsEUDO-uRic Acid. 



The interesting syntheses of uric acid and of the purin bases by 

 Traube (1900) are also affected through the intermediate formation 

 of pyrimidin bodies. 



Episarkin, C^H^NjO. — This base was isolated by Balke in 1893 

 from urine. From about 1,600 liters of urine only about 0.4 

 g. was obtained. It accompanied the hypozanthin silver nitrate. 

 The mixture on digestion with dilute ammonia on a water-bath 

 gave hypoxanthin-silver, whereas episarkin, in part, passed into 

 solution. The solution was filtered, and the slightly ammoniacal 

 filtrate on standing for twelve hours gave a crop of small needles 

 of episarkin. The hypoxanthin-silver still contained an admixture 

 of the new base, as was found by decomposition with hydrogen 

 sulphid and concentration. 



The crystals are more difficultly soluble in water and their 

 crystalline form is distinctly different from that of hypoxanthin. A 

 separation can best be accomplished by dissolving the mixture of the 

 two bases in as little dilute ammonia as possible, then on saturating 

 this solution with carbonic acid small whetstone-shaped needles 

 separate. In this respect it resembles epiguanin. When recrystal- 

 lized from hot water it yields small prisms or needles which may 

 attain a length of 1 cm. and may be grouped in bunches. They are 

 white and glassy, and when dry form a felt-like mass. The crystals 

 are permanent and do not effloresce. 



On evaporation with concentrated nitric acid, it gives a yellow 

 residue which with sodium hydrate becomes paler. On evaporation 

 with nitric acid and chlorin water (Weidel's reaction), it gives a 

 white residue unaltered by ammonia. When evaporated on a water- 

 bath with hydrochloric acid and potassium chlorate it leaves a white 

 residue, which becomes colored an intense violet by ammonia. This 

 reaction certainly shows that this base is related either to the 

 purin or to the pyrimidin bodies. 



