136 ANIMAL CHEHISTKY LECTURE VI. 



deuce that they really are so constituted is anything but satis- 

 factory. The relations of lantanuric and oxaluric acids to another 

 uric acid product known as oxaluramide are obviously those of 

 hydrogen and water to ammonia, as illustrated in the case of so 

 many previously considered compounds, thus : 



H.H Hydrogen C 3 N a H 3 (H)0 3 Lantanuric. 



H.HO Water C 3 N a H 3 (HO)0 3 Oxaluric. 



H.H a N Ammonia C 3 N a H 3 (H a N)0 3 Oxaluramide. 



Allantoine, as shown by the fine specimen lent me by Messrs. 

 Hopkins and Williams, is a beautiful crystalline body existing in 

 the allantoic fluid of the fetal, and in the urine of the sucking 

 calf. It has also been noticed by Frerichs and Stadeler in the 

 urine of two dogs, upon whose lungs they had been experiment- 

 ing, and is easily procurable from uric acid by oxidation with 

 peroxide of lead. By deoxidation, it yields glycoluril (Rheineck). 

 Mycomelic acid may be obtained, among other processes, by 

 heating uric acid with water under pressure,* thus : 



Uric acid Mycomelic acid Carbonic oxide 



C 5 N 4 H 4 3 = C 4 N 4 H 4 0, + CO. 



As I have before observed, it stands to paraban in exactly the 

 same relation that uric acid stands to alloxan. From the obser- 

 vations of Hlasiwetz it seems probable that some supposed urate 

 of ammonia deposits, occurring in urine, really consist of myco- 

 melic acid, which similarly evolves ammonia when treated with 

 alkalies, and yields murexide when evaporated with nitric acid. 



(144.) Ofmesoxalic mon-ureides, alloxan and barbituric acid 

 appear to be the most important. Alloxan, the first discovered 

 product cf the artificial oxidation of uric acid, has recently been 

 recognised by Liebig as a pre-formed constituent of urine. By 

 treatment with bromine, it yields dibromobarbituric acid, 



* Possibly, thus : 



Uric acid Water Mycomelic Formic 



C 5 N 4 H 4 3 + H a O = C 4 N 4 H 4 O a + CH a O a . 



