ACTION ON MINERALS 93 



ing water into the drains, there to be precipitated. These 

 bacteria are often to be noted in masses in iron springs. 



It is quite probable that the soil bacteria influence the 

 tilth of the soil; that they influence the loss of moisture 

 from it; and that they are the cause of the earthy odor that 

 is so characteristic. This is due to volatile substances 

 formed in the decomposition of the organic matter in the 

 soil. 



