THE SOIL PARTICLE 



85 



(Fig. 17), devised by Whitney, 1 presents a simple method for 

 the identification of a soil from a mechanical analysis. The 

 convenience of such a triangular representation is obvious. 



CLAY 

 100 



10 20 50 40 50 60 70 80 9Q 10Q SlLT 



PER CENT 



Fig. 17. — Diagram for the determination of class from a mechanical 

 analysis. In using the diagram the points corresponding to the 

 percentages of silt and clay are located on the silt line (abscissa) 

 and clay line (ordinate) respectively. Perpendiculars at these 

 points are then projected inward until they intersect. The name 

 of the compartment in which the intersection occurs gives the class 

 name of the soil in question. 



46. Soil survey classification — soil type. — The function 

 of the soil survey is to investigate the nature and occurrence 



1 Whitney, M., The Use of Soils East of the Great Plains Megion; 

 U. S. Dept. Agr., Bur. Soils, Bui. 78, p. 13, 1911. 



