116 ANIMAL OXIDES WITH AZOTE NOT OILY. 



ters of an acid ; for when it comes in contact with a base it is 

 immediately decomposed. 



When barytes water is added to a solution of alloxantin, a 

 copious precipitate of a fine violet colour falls, which becomes 

 white, and then disappears entirely when the liquor is boiled. An 

 excess of barytes throws down a fine white precipitate. The reac- 

 tion of alloxantin with nitrate of silver is very remarkable. As soon 

 as the two liquids come in contact, a black precipitate of metal- 

 lic silver falls, though no gas whatever is evolved, nor any thing 

 else thrown down. When the liquid is separated from the me- 

 tallic silver by filtration, barytes water throws down a white pre- 

 cipitate from it. With selenious acid it acts in the same way, a 

 red precipitate of selenium falling. 



When alloxantin is placed in an atmosphere containing gase- 

 ous ammonia, it assumes a red colour, its crystals become opaque, 

 and lose no weight though exposed to a temperature of 212. 

 At a higher temperature they lose water. 



Alloxantin was subjected to an ultimate analysis in Liebig's 

 laboratory. The mean of four different analyses gave 

 Carbon, . 30-06 or 8 atoms = 6-0 or per cent 29-82 

 Hydrogen, . 3*16 or 5 atoms = 0.625 ... 3-10 

 Azote, . . 17-53 or 2 atoms =3-5 ... 17-40 



Oxygen, . . 49-25 or 10 atoms == 10-0 ... 49-68 



100-00 20-125 100- 



This gave the formula C 8 H 5 Az 2 O 10 = 20-125. So that al- 

 loxantin differs from alloxane by containing an additional atom 

 of hydrogen. 



When alloxantin is formed in dilute nitric acid, one atom of 

 oxygen only instead of two unites to the elements of the acid, C 8 

 Az 2 O 4 , which, united to urea, constitutes uric acid. Hence the 

 nitric is converted into nitrous acid (Az O 4 .) This acid, by the 

 contact of water, is decomposed into hyponitrous acid (Az O 3 ), 

 and nitric acid ( Az O 5 ) ; only one of these decomposes the urea. 

 The consequence is, that a quantity of urea remains undecom- 

 posed in the liquid. Accordingly, if we add nitric acid, crystals 

 of nitrate of urea are deposited. 



When alloxane is treated by deoxygenizing bodies, it is con- 

 verted into alloxantin. Thus, if we pass a current of sulphuret- 

 ted hydrogen gas through a moderately concentrated solution of 



