OXALIC ACID. 931 



tion of the bark clarified by albumen, and having its tannin 

 precipitated by isinglass, evaporated to an extract and treated 

 as usual with strong alcohol. It requires about 400 parts of 

 boiling water for solution, but dissolves in 4 or 5 parts of 

 absolute alcohol. It is deposited in little cauliflower looking 

 masses, which by a magnifying power of 10 times are seen to 

 be composed of small crystals. It yields by dry distillation a 

 yellow liquid ; which soon solidifies as a clear yellow mass ; 

 this Chevreul considered as unaltered quercitrin. As it restores 

 the cplour of reddened litmus paper, and combines with and 

 neutralises bases, M. Bolley considers it an acid and names it 

 Quercitronic acid. The formula of the crystallized acid, which 

 agrees with analysis, is HO + C 16 H 8 O 9 , of the salt of lead 

 PbO -fC 16 H 8 O g . Herm. Trommsdorff found polychrome to have 

 the same composition, and represented it by the same for- 

 mula halved.* 



CHAPTER VIII. 



ACIDS. 



SECTION I. 

 ACIDS SUPPOSED TO CONTAIN CARBONIC OXIDE. 



Carbonic acid, and chlorocarbonic acid, may be considered as 

 combinations of carbonic oxide, as they are formed by the union 

 of that radical with oxygen and chlorine. Carbonic oxide also 

 unites with potassium, and by the decomposition of this com- 

 pound, croconic and rhodizonic acids are produced. Oxalic and 

 mellitic acids also appear from their composition to contain the 

 same radical. 



OXALIC ACID. 



Formula of the hydrated acid, HO,C 2 O 3 + 2HO. This acid, 

 discovered by Scheele in I776j exists in the form of an acid salt 



* Liebig's Annalen, xiv, 205. 



2 P P 2 



