94 OF THE INORGANIC 



than the branches., and the branches more than 

 the stem. The potato plant contains more potash 

 before blossoming than after it. 



The acids found in the different families of plants 

 are of various kinds ; it cannot be supposed that 

 their presence and peculiarities are the result of 

 accident. The fumaric and oxalic acids in the 

 liverwort^ the kinovic acid in the China nova, the 

 rocellic acid in the Rocella tinctoria, the tartaric 

 acid in grapes, and the numerous other organic 

 acids, must serve some end in vegetable life. But 

 if these acids constantly exist in vegetables^ and are 

 necessary to their life, which is incontestable, it is 

 equally certain that some alkaline base is also in- 

 dispensable in order to enter into combination with 

 the acids which are always found in the state of 

 salts. All plants yield by incineration ashes con- 

 taining carbonic acid ; all therefore must contain 

 salts of an organic acid. 



Now, as we know the capacity of saturation of 

 organic acids to be unchanging, it follows that the 

 quantity of the bases united with them cannot vary, 

 and for this reason the latter substances ought to 

 be considered with the strictest attention both by 

 the agriculturist and physiologist. 



We have no reason to believe that a plant in a 

 condition of free and unimpeded growth produces 

 more of its peculiar acids than it requires for its 

 own existence ; hence, a plant, on whatever soil it 

 grows, must contain an invariable quantity of alka- 



