EXPERIMENT STATION BULLETINS. 441 



insoluble nitrogen in their mixtures to be derived from high-grade 

 materials. 



The fourth column shows the total amount of nitrogen in the sample. 

 It is equal to the sum of the first three columns. 



Phosplioric Acid. Three divisions are included under this heading, 

 designated as "total," ''insoluble" and "available." The "total" phos- 

 phoric aoid includes all of this ingredient in the sample. The "insoluble" 

 phosphoric acid represents tliat portion that is unavailable and the 

 "available" phosphoric acid, is, as the name implies, readily available. 

 The available phosphoric acid represents the difference between the total 

 and insoluble phosphoric acid. 



Potash. The results shown under this heading are those soluble in 

 water as required by the law. Water-soluble potash is, of course, 

 readily available. 



