102 



CHEMISTRY OF FARM PRACTICE 



to slake it before it can be spread. This is often accom- 

 plished by putting the material in small piles at regular 

 intervals over the field and covering the piles with moist 

 earth, which promptly water-slakes the lime, making it 



a 



FIG. 35. Effect of liming spinach. (R. I. Exp. Station.) 



into a powdered condition in which it may easily be spread 

 from the piles. 



A number of State Experiment Stations have investi- 

 gated the use of lime, in various forms, with the general 

 conclusion that best results are obtained from the use of 

 calcium carbonate. Results at the Pennsylvania Station, 

 covering a period of over sixteen years, indicate that on 



