FLOCCULATION 



327 



the soil was not nearly so evident as when the 2O-day period was 

 taken : but the time required for the rain to produce its full effect 

 on the soil would necessarily vary considerably with different 

 soils. 



0.5 



Fine part/c/es, actuaJ in 18 



Fine parti c/es, re ht/ve /n upper 6." 



20 



/O 



July. Auy. top*. Oef, Vo. Oec. Jan. fko H*r. Ap. Myy. June. July *" 

 FIG. 46. FLOCCULATION AND RAINFALL. 



The action of frost on a clay soil improves its working 

 capabilities, just as much as, and even more than, a favourable 

 dressing does, and suggests, at first, that frost must cause floccula- 

 tion. As a matter of fact, however, it was found that the action 

 of frost was essentially of a diametrically opposite character 

 to that of a flocculating agent, for it tended to reduce, instead of 

 to increase, the size of the ultimate particles of the clay. Much 



