126 



CHEMISTRY OF FARM PRACTICE 



liberate potassium or ammonium; and potassium to liberate 

 ammonium; the converse of the above. This is termed 

 mass action. When heavy applications of lime are made, 

 mass action ensues and much stored- up plant food is 

 liberated. 



Certain salts have the power of absorbing water from 



FIG. 46. Opening up a trench after blasting; extraction of caliche 

 by piece work. 



the atmosphere. This property is termed deliquescence. 

 A very deliquescent material may be hard to preserve 

 in a good mechanical condition, as it may absorb enough 

 moisture to become sticky or even to dissolve in the water 

 taken in. 



93. Potassium Nitrate, " Niter," " Saltpeter." This 

 salt is the least deliquescent of the three common commer- 

 cial nitrates. It contains nitrogen and potassium both 



