i *fhe Principles of Part L 



they are very hot, becaufe fand is fufcep^ 

 tible of a greater heat from the influence of 

 the fun, and will retain it longer than 

 water does. 



SAND cannot fwell by the addition of 

 water -, becaufe that quality in rich foils is 

 owing to an intefline fermentation, which 

 goes on in them. But in fand there are no 

 particles, and in fandy foils too few, which 

 are capable of fermentation. Hence a de-^ 

 feet of nutritious particles in fandy foils, 

 Inftead of fwelling, it diminishes in bulk 

 when wet 5 becaufe the water rufhing in, 

 difpofes the particles more regularly, fb 

 that the interftices are better filled up than 

 before, and its bulk leflened. 



THE faults, then, of the fandy foil are, 

 that it lets water pafs through it too eafily, 

 and that it contains too few nutritious 

 particles. Whatever compofl is ufed to this 

 foil, muft correct one or both of thefe 

 faults. Clay will help it to retain the wa- 

 ter 5 



