98 ACTION OF SALTS. 



suppose there is added a salt, composed of muriatic 

 acid and soda, that is common salt, to the soil. By 

 the action of the living plant, this is decomposed. 

 Its soda or base, then acts on geine. If this has 

 been long in an insoluble) and perfectly useless con- 

 dition, it is now rendered soluble, and hence sup- 

 plies plants with food. A very marked and decided 

 effect is perceived from applying a small quantity 

 per acre, of a salt, which certainly of itself, con- 

 tains no nutriment for plants. 



150. The effects here produced, may be due to 

 the small quantity of alkali, acting on an indefinite 

 quantity of geine ; but the effect so often observed, 

 of the minute quantity of salts, say one-hundredth 

 of one per cent, seems hardly compatible with the 

 explanation. So far as it goes, this is its action ; 

 but very probably the quantity of alkali in the salt 

 sown, is taken up as a geic salt, and immediately 

 carried into the plants. The base then is with- 

 drawn, yet the action continues. It continues 

 through the whole time the fruit is forming. Some 

 other source, therefore, of the permanence of this 

 action must be sought. That is due to the acid 

 constituent of the salt. That, when the plant de- 

 composed the salts, was let loose and now acts on 

 the silicates of the soil. It decomposes these, unit- 



