DIALURIC ACID. 51 



Its solution precipitates salts of barytes, white ; salts of lead 

 in yellow flocks. The precipitate becomes violet when exposed 

 to the air. The salts of silver are immediately reduced by it. 



When decomposed by oxide of copper the volume of azotic 

 gas evolved is to that of the carbonic acid gas as 3 : 8. The 

 mean of three analyses made in Liebig's laboratory by means of 

 oxide of copper gave 



Carbon, 31-27 or 8 atoms 6 or per cent 29*82 

 Hydrogen, 4-49 or 7 atoms = 0-875 ... 4-34 



Azote, 27-36 or 3 atoms = 5-25 ... 26-09 



Oxygen, 36-88 or 8 atoms =. 8-00 ... 39'75 



100 20-125 100* 



If from C 8 H 7 Az 3 O 8 we subtract H 3 Az, or an atom of am- 

 monia, the remainder C 8 H 4 Az 2 O 8 must give us the constitu- 

 tion of dialuric acid. Its atomic weight is 18. We may con- 

 sider it as alloxane minus 2 atoms of oxygen, or alloxantin minus 

 1 atom oxygen and 1 atom water. 



Dialurate of ammonia dissolves in potash with the disengage- 

 ment of ammonia. The acids throw down nothing from the so- 

 lution. 



The attempts of Wohler and Liebig to obtain dialuric acid in 

 an isolated state were unsuccessful. When separated from its 

 base it is decomposed with great facility into a great number of 

 products which have not yet been accurately examined. 



* There is obviously a mistake in the numbers given in Liebig's paper, (An- 

 nalen der Pharmacie, xxvi. 277.) The data given, 



1st. 0-5095 grammes of dialurate of ammonia gave 0-215 water, and 0-542 

 carbonic acid. 



2rf. 0-430 of the salt gave 0-163 water and 0-5635 carbonic acid. 

 3d. 377 gave 0- 455 water and - 404 carbonic acid. 



0-455 water in the third experiment is probably a typographical error for 0-155. 

 But 0-5095 of the salt furnished less carbonic acid than 0-430. This must be 

 a mistake, which affects the quantity of carbon, which of course acts upon the 

 azote and the oxygen. Liebig's numbers are 



Carbon, . . 29-830 

 Hydrogen, . . 4-406 

 Azote, . . 25-913 



Oxygen, . . 39-851 



100 

 Numbers coming very near those deduced from the formula C 8 H 7 Az 3 O 8 . 



