SOIL 



87 



by the poor and sandy " Barrens." The one is underlaid 

 by limestone and the other by sandstone. 



The soil at the surface is usually finer than the soil a 

 foot or so below the surface, and sometimes it has a great 

 deal of decayed -vegetable matter mixed with the decom- 

 posed rock, and to this its fertility is often largely due. 

 Some soils are made up almost entirely of decayed vege- 

 table matter, peat and muck. The underlying coarser 

 and lighter colored soil, which contains little if any vege- 

 table matter, is usually called the subsoil. 



Experiment 47. Examine under a strong magnifying glass 

 samples of sand, loam, clay, peat and other kinds of soil. Notice the 

 different kinds of particles composing the different soils and the 

 shapes of these particles. 



Experiment 48. Put a handful of ordinary loamy soil into a. fruit 

 jar nearly full of water and allow it to stand for a day or two, shaking 

 occasionally. At the end of this 

 time shake very thoroughly and 

 after allowing it to settle for a 

 minute, pour off the muddy water 

 into another jar. Allow this to 

 stand for about an hour and then 

 pour off the roily water and evap- 

 orate it slowly, being careful not 

 to burn the material left. Ex- 

 amine with the eye, by rubbing 

 between the thumb and fingers, 

 and with a magnifying glass, the 

 three substances thus separated. 

 These three separates will be 

 composed largely of sand, silt 

 and clay. 



If a compound microscope is 

 available, mix a bit of the silt and 

 of the clay in a drop of water and Fi 43> 



put these drops on glass slides. 



Examine the drops under the low power of the microscope. Notice 

 the little black particles of decayed vegetable matter, also the little 



