218 PHYSICAL PROPERTIES OF SOIL. 



ical properties of soil. The physical properties then, 

 are the foundation of the great diversity which soil 

 exhibits. The subject of soil, will be very imper- 

 fectly treated, if a few pages are not devoted to this 

 important subject. The physical characters of soil, 

 are embraced under the terms, cold, hot, wet, and 

 dry land. These characters are dependent on four 

 circumstances. 



292. First, the absolute weight of a given 

 bulk of soil, 

 Secondly, its colour, 

 Thirdly, its consistency, 

 Fourthly, its power of retaining water. 

 In other words, the physical characters of soil may 

 be considered under- 

 First, its relation to heat, 

 Secondly, its relation to moisture and gas, 

 Thirdly, its consistency, 

 Fourthly, its electrical relation. 

 The relation to consistency makes soil light, or 

 heavy ; the relation to heat and moisture, makes soil 

 hot or cold, dry or wet. The great natural varieties 

 of soil are, sand, clay, and loam ; first, the great dis- 

 tinction in the scale of soil, is sand and clay : all in- 

 termediate varieties proceed from mixtures of these, 

 with each other. Now the sand may be siliceous, 



