EXPERIMENT STATION BULLETINS. 181 



phosphate rock. By adding together the "Available" and "Insoluble" 

 we get the "Total P 2 5 ." 



The "Potash soluble in water estimated as K 2 0," is the soluble potash 

 salt estimated only as regards the oxide of potassium = K 2 = oxide of 

 kalium or potassium. Since potash is often used in the form of sulphate 

 of potash (K,S0 4 ), a second estimate is added of that combination, but 

 the real potash in both columns is the same. 



