OXYGEN. 75 



ing than after.* The leaves are the part of 

 the plant which contains the greatest quantity 

 of these bases, and hence their absorption of a 

 larger quantity of the gases forming the va- 

 rious salts met with in the vegetable tribe. 



There are many other peculiar acids which 

 are found by analysis to exist in the substance 

 of plants, but as they do not exist ^er se^ in a 

 gaseous or other state, but as a general rule 

 are composed of various proportions of oxygen 

 combined with other gases and united with 

 some base, it is not intended to pursue this 

 branch of the subject farther, as the considera- 

 tion of each, peculiar acid would lead us far- 

 beyond the limits proposed. It is simply 

 necessary to repeat that in almost every case* 

 oxygen forms the acidifying principle. 



* Liebig. 



