THE SOIL 



77 



Fine 



travel 

 3% 



Coarse Medium Fine Very tine 



sand sand sand sand 1 



3.3 % 4.3 % 37.8 % 21.5 % 



FIG. 41. Composition of a fine sandy loam 



poured off, we shall have the soil separated into three sizes 

 of particles. Any number of divisions can be made in this 

 manner. 1 



The finest soil particles are called clay, the next small- 

 est silt. The larger particles are different grades of sand 

 and gravel. The following table shows the mechanical 

 analyses of three important soil types as separated by 

 the Bureau of Soils: 



common method of making the separation is to put the samples 

 of soil in bottles of water, and shake for a day in a shaking machine. This 

 separates the particles that are stuck together. A centrifugal machine is 

 used to aid in making the separations, as it is more rapid than watting for 

 the particles to settle. The material is usually separated into three grades 

 by means of water. The sands are further separated by means of sieves. 



Coarse Medium Fine Very fine 



sand sand sand sand 



0.3% 0.4% 1.5% 3.1% 



Fio. 42. Composition of a clay loam 



Silt 



