206 AGRICULTURAL CHEMISTRY 



taric acid or argol found in grapes, and from which cream 

 of tartar is prepared. There are a large number of or- 

 ganic acids found in plants and food materials, and in the 

 study of organic chemistry; these acids constitute an im- 

 portant part.) In this work, only a few of the more 

 common organic acids are considered. 



274. Tartaric Acid is the characteristic acid of grapes. 

 It is also found in small amounts in pineapples, cucum- 

 bers and potatoes. It can be produced in the laboratory 

 by the oxidation of milk-sugar and other carbohydrates. 

 Crude tartar or argol, from which commercial cream of 

 tartar is made, is deposited when grape juice ferments. 

 When tartaric acid is neutralized with bases, tartrates 

 are formed. Sodium potassium tartrate (Rochelle salt) 

 is one of the most important salts of tartaric acid. 



275. Malic Acid occurs in many vegetables and small 

 fruits, as tomatoes, currants and strawberries. It is the 

 organic acid which occurs most abundantly in small 

 fruits. Malic acid can be produced from tartaric acid 

 by the action of hydrochloric acid. 



276. Succinic Acid is found in many plants, and also 

 in animal tissues. Small amounts of this acid are formed 

 when dextrose undergoes alcoholic fermentation. Suc- 

 cinic acid occurs also in soils, particularly those of a 

 peaty character. It can be produced from malic acid by 

 the action of hydrochloric acid. Chemically, the three 

 acids, tartaric, malic and succinic, are closely related. 



277. Oxalic Acid is found in small amounts in nearly 

 all plants, particularly those of the oxalis variety. In 



