THE SOIL. 



39 



PHYSICAL PROPERTIES OF SOME SOILS. 



This table shows the relative properties of different soils 

 examined under similar conditions. 



The "Specific Gravity" of the soil is not a point of 

 any great importance. The above figures give the specific 

 gravity of clay soil from 2 '53 and sandy soil, 2*63. 

 A cubic metre of dry loose loam soil weighs about 1,300 

 kilograms, and when wet about 1,700 kilograms. 



The " Porosity " of the soil is calculated from the rela- 

 tion of the soil particles to the total volume of soil. Soils 

 which are composed of a mixture of large and small 

 particles have usually the smallest volume of pores. Clay 

 soils have a high "pore- space" but, at the same time, they are 



