ACID AND ALKALINE SECRETIONS. 73 



of this secretion are in the Cinchona offi- 

 cinalis or Peruvian bark, Lambert Cinchona, 

 t. 1, and every species, more or less, of 

 Gentian. 



-Acid secretions are well known to be very 

 general in plants. Formerly one uniform vege- 

 table or acetous acid was supposed common 

 to all plants, but the refinements of modern 

 chemistry have detected in some a peculiar 

 kind, as the Oxalic acid, obtained from Oxalis 

 or Wood Sorrel, and several others. The 

 astringent principle should seem to be a sort of 

 acid, of which there are many different forms 

 or kinds, and among them the tanning prin- 

 ciple of the Oak, Willow, &c. 



On the other hand, two kinds of Alkali 

 are furnished by vegetables, of which the 

 most general is the Vegetable Alkali, pro- 

 perly so called, known by the name of Salt 

 of Tartar, or Salt of Wormwood, or more cor- 

 rectly by the Arabic term Kali. The Fossil 

 Alkali, or Soda, is most remarkable in cer- 

 tain succulent plants that grow near the sea, 

 belonging to the genera Chenopodiinn, Sal- 

 sola, &c. When these plants are cultivated 

 in a common soil, they secrete Soda as copi-. 



