492 THE CHEMISTRY OF CREATION. 



But in every shower falling on the land, wash- 

 ing out certain mineral ingredients, and by 

 various channels directing them into the great 

 receptacle, we may perceive a large source of 

 impurity, and the question comes to assume a 

 great importance when we note by what means 

 are the otherwise inevitable consequences of 

 these additions to the mineral constituents of 

 sea-water to be averted. The provision to 

 this end is to be found in the varied tribes of 

 marine plants. It will be most evident what 

 ingredients these plants appropriate and sepa- 

 rate from the element in which they live, if 

 we examine into the chemical nature of their 

 ashes. This will infallibly inform us in the 

 most correct manner how far they act in the 

 preservation of the purity and constant com- 

 position of the waters of- the ocean. 



From analysis it is found that sulphuric acid 

 and chlorine, potash, soda, lime, and magnesia 

 are the chief constituents. The sulphuric acid 

 and chlorine occur in combination with the 

 other substances. The quantity of sulphuric 

 acid is very large ; on an average, according to 

 Professor Forchhammer, it amounts to four 

 per cent, in the dry plant. Thus it is evident 

 that a large amount of this acid, which would 

 otherwise, in the -form of various combinations, 

 accumulate in sea-water, is separated by sea- 



