ANIMAL ACIDS DESTITUTE OF AZOTE. 



3 atoms carbon, = 2*25, or per cent 6*57 



4 atoms oxygen, = 4 '00, ... 11-67 

 2 atoms oxide of lead, = 28.00, .., 81-76 



100-00 



This would make mesoxalic acid C 3 O 4 = 6-25, or it is equi- 

 valent to two atoms carbonic acid, together with an additional 

 atom of carbon. Admitting this composition to be correct, we 

 have no fewer than five acids composed of carbon and oxygen, 

 namely, 



Croconic, . C 5 O 4 



Mesoxalic, . C 3 O 4 



Oxalic, . C 2 O 3 



Rhodizonic, . C 3 O 5 



Carbonic, . C O 2 



Liebig is of opinion that the want of exact accordance between the 

 analytical and theoretical numbers in the above analysis was owing 

 to the presence of a little cyanate or cyanurate of lead in the me- 

 soxalate subjected to analysis. This, however, can only be con- 

 sidered as a plausible explanation. Additional experiments are 

 still wanting to decide the point completely. Meanwhile, if we 

 admit the constituents of mesoxalic acid to be as above stated, it 

 is easy to explain the conversion of mesoxalate of silver by heat 

 into metallic silver and carbonic acid. Mesoxalate of silver must 

 be a compound of 



1 atom mesoxalic acid, . C 3 O 4 



2 atoms oxide of silver, . 2 (Ag O) 



By heat the two atoms of oxygen leave the silver and combine 

 with the mesoxalic acid. We have consequently C 3 O 6 -f 2 Ag. 

 but C 3 O 6 is equivalent to three atoms of carbonic acid. 



When a solution of alloxanate of barytes is boiled, it under- 

 goes decomposition. A white precipitate falls, which is a mix- 

 ture of mesoxalate, alloxanate, and carbonate of barytes. When 

 calcined, it gives out a notable quantity of hydrocyanic acid and 

 effervesces feebly with acids. When the liquid separated from 

 this precipitate is evaporated, it gives a yellow foliated mass of 

 mesoxalate of barytes, which may be purified by washing it with 

 alcohol. When this salt was heated with oxide of copper, it gave 

 no trace of azote ; 100 parts of it gave 72-1 of carbonate of ba- 



