EFFECTS OF ELECTRICITY. 69 



in the soil by the long tap roots of the clover plants and to 

 which the roots of other plants cannot reach; and that some 

 of this organic nitrogen, at least, may have been procured 

 from nitric acid produced in the deeper soil by the action 

 of electrical currents. Perhaps this source is over estimated ; 

 but it is certain that the action of electrical discharges 

 through the soil, which are quite as frequent as those through 

 the air, and from cloud to cloud, have as yet not been con- 

 sidered to any extent, if at all, in the discussions and inves- 

 tigations of this exceedingly important question : "where- do 

 plants procure their nitrogen?" 



