SODA. 85 



assimilation by the plant is the same, that is, 

 it must be taken up by the roots when in a 

 state of solution, and thus be distributed over 

 the whole plant, when its decomposition will 

 at once take place; in the case of the nitrate of 

 potash, the nitrogen is set free to combine with 

 other matters to form the gluten of the seed, 

 and in the state of carbonate, the carbonic acid 

 gas is assimilated as carbon, giving off the 

 oxygen, and in both cases the potash is set free 

 to form a base for the peculiar acid of the plant, 

 be it malic, oxalic, or any other. 



ON SODA. ) 



The next salt in the solid substances neces- 

 sary for the development of plants is now to be 

 explained, and its presence is so universal, that 

 the remarks we have made respecting potash 

 will equally apply to soda. 



It is found in almost all soils combined 

 with potash, but generally in a lesser propor- 

 tion and as a muriate of soda instead of a 

 nitrate. 



The sea is the great source of this salt, and 

 all marine plants, as well as plants growing 

 on or near the sea coast, assimilate this salt 

 instead of potash. It exists also abundantly 

 combined with chlorine (common salt) in va- 

 rious parts of the globe, and in our own coun- 

 try the native rock salt is a source of a consi- 

 derable commerce, and is the basis of many 

 changes. 



