50 ANIMAL ACIDS CONTAINING AZOTE. 



Were we to admit in the hydrous acid two atoms of water, its 

 constitution would be C 8 H 3 Az 4 O 3 -f 2 (HO), and its atomic 

 weight in the anhydrous state would be 16*375. But analogy 

 would lead to the inference that the hydrous acid contains only 

 one atom of water, and that its atomic weight is 17*5. 



When mycomelate of silver is heated by itself, it gives out a 

 great deal of cyanate of ammonia, which, when dissolved in wa- 

 ter and evaporated, becomes urea. There is formed besides a 

 crystalline substance, having a peculiar smell, and coloured red 

 by another matter. 



SECTION VIII. OF DIALURIC ACID. 



We owe the discovery of this acid also to Wohler and Liebig.* 



When a current of sulphuretted hydrogen gas is passed through 

 a solution of alloxane, this last substance is converted into allox- 

 antin. If we continue the current of sulphuretted hydrogen 

 through the boiling solution after all the alloxane is converted 

 into alloxantin, there is a new deposit of sulphur, and the liquid 

 becomes decidedly acid. If, after all the alloxantin is decom- 

 posed, we saturate the liquor with carbonate of ammonia, a great 

 quantity of white crystalline matter falls, consisting of dialuric 

 acid united to ammonia. 



We may obtain the same salt in abundance by dissolving uric 

 acid in dilute nitric acid, and mixing the liquid with sulphohy- 

 drate of ammonia, taking care that there is left in the liquid a 

 slightly acid reaction. The precipitate (which contains sulphur) 

 is to be washed, dissolved in boiling water, and treated with car- 

 bonate of ammonia. On cooling the liquid concretes into a 

 white crystalline mass. 



If we reduce alloxane by means of zinc and muriatic acid, and 

 after separating the crystals formed, we treat the residue with 

 carbonate of ammonia till the oxide of zinc, at first precipitated, 

 is again redissolved ; the same salt is deposited, provided the mix- 

 ture be left for some time in a state of repose. 



This white precipitate becomes red when dried at the common 

 temperature. At 212 it becomes blood red without losing am- 

 monia. It is very soluble in boiling water, but is mostly depo- 

 sited again when the solution cools, especially if we add carbonate 

 of ammonia to the liquid. 



* Ann. de Chim. et de Phys. Ixviii. 263. 



