FOOD FOR PLANTS 11 



The layer of "Caliche" is sometimes eight or ten feet 

 thick, but averages about three feet. This "Caliche" 

 contains on an average from 15 to 50 per cent, of pure 

 Nitrate of Soda. 



It is calculated there is ample Nitrate now in sight 

 to last upwards of three hundred years. 



The "Caliche" is refined by boiling in water to 

 dissolve the Nitrate. This hot water is then run off 

 and allowed to cool in tanks, when the Nitrate forms 

 in crystals like common salt. The Nitrate is then 

 placed in bags of about 176 pounds (or nearly two 



