Lactic Acid
in chemistry, C₂H₂O3 = CH3CH(OH)CO Oн. basic, diatomic acid, discovered by Scheele in sour milk, and first recognized as a distinct acid by Berzelius. It occurs in small quantity in the animal organism, especially in the gastric juice, and, under certain circumstances, is formed in the fermentation of some sugars. It is readily prepared by adding to a solution of grape sugar a small quantity of powdered old cheese, mixed with sour milk , and allowing the mixture to stand for 8 or 10 days at a temperature of 40° to 45°. It is a colorless, inodorous liquid of syrupy consistence, possessing an intensely sour taste. Lactic acid forms salts by the replacement of hydroxylic hydrogen by metals. Zincic lactate, Zincic lactate , hyd C6H10 ZnO63H2O, is the most characteristic salt of lactic acid. It crystallizes in colorless, monoclinic prisms, slightly soluble in cold water, very soluble in boiling water, but insoluble in alcohol.