62 DEPARTMENT OF AGRICULTURE GEORGIA. [348] 



Tannic acid is found in the bark and leaf of the oak and 

 other trees and plants. Its principal use is in tanning 

 leather. It is also used with copperas in making ink. 



Oxalic acid is found in considerable quantity in the sorrels. 

 It is a powerful acid, having a remarkable affinity for lime, 

 even displacing sulphuric acid. Hence an application of 

 lime is beneficial to the lands of Southern Georgia, on wnich 

 the sorrel grows, its effect being to neutralize this and 

 other injurious vegetable acids. The presence of sorrel 

 in considerable quantity may be regarded as an indication 

 that lime is needed. 



Acetic acid is the sour principle of vinegar, which is 

 an impure form of acetic acid, resulting principally from 

 the fermentation of the juices of fruits, but is also pro- 

 duced from any liquid containing sugar, by the use of a 

 ferment, by the oxidation of alcohol, from infusion of 

 malte and from a mixture of starch and yeast. 



Mother of vinegar, which consists of an aggregation of 

 microscopic plants (ulvina aceti) is produced in acetous 

 fermentation which it not only facilitates, but probably 

 causes. 



Vinegar is made rapidly from fermented or fermenta- 

 ble liquids, by passing them repeatedly through oakery bar- 

 rels filled with beech shavings, previously steeped in strong 

 vinegar, increasing the temperature of the liquid at each 

 filtration. Vinegar made from wine or cider is most highly 

 esteemed for domestic uses. 



Prussic acid is found in a very dilute state in the bark and 

 leaves of the cherry, and peach, and also in the kernels of 

 most stone fruits. It is present in considerable quantity 

 in the bark of the wild cherry, the medicinal properties of 

 which are attributed to the influence of this acid. 



Vegetable oils are divjded by distinct characteristics into 

 fatty or fixed oils, and essential or volatile oils. These 

 exist as minute, transparent globules in the cells of plants, 

 and may generally be extracted by simple pressure. In the 



