56 



CHEMISTRY OF FARM PRACTICE 



6 inches of coarse gravel, followed by E, 6 inches of fine 

 gravel. The top layer consists of 30 inches of sand. Chan- 

 nels (shown at X) are used to collect the water; they are 

 situated half in the bed of clay and half in the large rocks. 

 The best size of sand to use is 0.5-1.0 millimeter in diam- 

 eter, and the greater the uniformity obtained in the size 

 of the sand the better the filtration obtained. 



46. Boiled Water. Water is purified for drinking pur- 

 poses by boiling. This method can easily be used and is 

 quite inexpensive and effective. 



FIG. 18. A simple apparatus for distilling water. 



47. Distilled Water. Distilled water is pure, but it 

 needs aeration to become palatable, as it has a flat taste. 

 In Fig. 18 is shown an apparatus for distilling water. 



48. Boiler Water. In limestone regions, we find hard 

 water; in soils derived from sandstone and granite, soft 

 water occurs. Water, however, does not always partake 

 of the nature of the topsoil. Especially is this true when 

 the sources of supply are wells, because the water may have 

 come in contact with different strata below the surface. 

 If possible, water to be used in boilers should be analyzed, 

 and a suitable supply selected before installing the power 

 plant; otherwise a hard crust or scale will deposit over the 



