26 PRACTICAL AGRICULTURAL CHEMISTRY [61-63 



SECTION III 



EXPERIMENTS ON SOILS, MANURES, FEEDING 

 MATERIALS, AND DAIRY PRODUCE 



EXPERIMENTS ON SOILS 



61. Arable soils consist principally of four substances- 

 sand, clay, limestone, and humus or organic matter — 

 and the varieties of soil are named according to the pro- 

 portions in which the above constituents are present. Thus, 

 certain soils are known as sandy soils, clay soils, limestone 

 soils, and peat soils. Besides these are loams, which 

 contain both sand and clay in large quantities; marls, 

 which consist principally of limestone and clay ; and cal- 

 careous soils, in which sand and limestone occur together. 



62. Separation of Sand and Clay. — Place ina3-ia 

 evaporating-basin about as much dried loam as will cover a 

 penny. Half fill the basin with distilled water, and boil it for a 

 few minutes. Stir up and pour out the whole of the contents 

 into a small beaker. Allow the beaker to stand for a few 

 minutes, then pour off the cloudy liquid into another beaker, 

 leaving the sediment behind. Now hold the beaker contain- 

 ing the sediment over a sink and allow water to run into it 

 for a few minutes. The fine particles of clay will be washed 

 away, and very soon the water will run off quite clear The 

 residue in the beaker is sand. 



63. Action of Lime on Clay. — Frequently imie is 

 added to a clay soil to make it more open and sandlike in 

 its properties. To illustrate this action pour into two test- 

 tubes a little of the clay-water prepared in the last experiment. 

 To one of these add a thimbleful of lime-water and allow 



