SACCHAKIC ACID. 191 



Mannitic add, C 6 H 12 7 , is produced, together with 

 mannitose, by the oxidation of mannite, under the 

 influence of platinum-black. Amorphous, gummy 

 mass, easily soluble in water and alcohol. Apparently 

 bibasic. 



Dextrinic acid, C 6 H 12 7 . Is obtained from dextrin, 

 the same as glucic acid from grape-sugar. Colorless 

 syrup, which does not crystallize. 



Lactonic add, C 6 H 10 6 . Is obtained from sugar of 

 milk, or gum Arabic, in the same way as glucic acid 

 from grape-sugar. 



C. BIBASIC, HEXATOMIC ACIDS, OH 2W - 2 8 . 



1. Saccharic Add. 

 C 6 H 10 8 =C 6 H 4 (OH) 4 | QQOH. 



Formation. By careful oxidation of mannite, cane- 

 sugar, grape-sugar, fruit-sugar, starch, and other carbo 

 hydrates with nitric acid. 



Properties. Gummy, uncrystallizable, very deliques 

 cent mass, also very easily soluble in alcohol. By 

 further oxidation, it is converted into tartaric acid 

 and then into oxalic acid. 



The add potassium salt, C 6 H 8 8 .HK, and the add 

 ammonium salt, C 6 H 8 8 .HNH 4 , are difficultly soluble in 

 cold water (in from 80 to 90 parts), easily crystallizable,, 

 and, hence, are well adapted to the separation of 

 saccharic acid from the excess of nitric acid in the 

 preparation of the former. The neutral alkaline salts 

 are deliquescent ; the remaining salts are mostly insolu 

 ble or difficultly soluble in water. 



2. Mudc Acid. 

 C 6 H io 8 = C 4 H 4 (OH) 4 | QO OH. 



(Isomeric with saccharic acid.) Is formed, generally 

 together with saccharic acid, by careful oxidation of 



