THE RIVER. 143 



and animals. Potass and soda are the alkalis usually 

 found in vegetables ; and the acids, with which they 

 are found in combination, are, principally, the carbonic 

 and acetic ; though, in saline plants growing near the 

 sea, there is usually a small portion of muriate of soda, 

 or common salt. Now these combinations are easily 

 dissolved by sulphuric or nitric acids, and the com- 

 pounds which these form with the alkalis cannot be 

 again dissolved by the weaker acid ; so that if potass 

 of soda be once united to either of those acids, it 

 ceases to be fit for entering into the vegetable structure. 

 The alkali which is found most abundant in animal 

 structures, is soda, and the acids with which it is found 

 combined are principally the muriatic and phosphoric, 

 or some having a weaker attraction for it than the 

 muriatic. Ammonia is obtained abundantly in the de- 

 composition of animal matter ; but there is much reason 

 to believe that it is formed during the process. Now, 

 whenever any of those salts are changed to the nitrate 

 or the sulphate, or when any of their alkaline bases 

 are combined with nitric or sulphuric acid, combina- 

 tions that are sure to take place in every instance 

 when the salt or the base comes in contact with either 

 of these acids, a substance is formed which cannot, by 

 any natural process of which we have any knowledge, 

 be again separated so that the alkali may again enter 

 into the composition of an organic structure. Thus, if 

 these substances were allowed to remain, they would 

 gradually accumulate, and the termination both of 

 animal and of vegetable life would be the consequence. 

 Of this we have many proofs : in those warm regions 

 which, through the want of irrigation by water, have 



