wherry: acidity and ai^kaunity 



307 



stated, it is understood that it is + when applied to a positive 

 ion and — to a negative one. 



In the last column are given descriptive terms for such re- 

 actions as are commonly met with in soils. In the study of soils 

 associated with various native plants the writer has found that 



" May be grouped together as "circumneutral." 



certain more or less well-defined types of reaction can be rec- 

 ognized, and it seems desirable to have a special name to apply 

 to each of these. Starting at the acid end of the series, and using 

 for simplicity the numerical specific acidities and alkalinities, 

 these are as follows; • - 



