PHYSICAL COMPOSITION OF SOILS. 



9 1 



in it the upward current ascends in a conical glass tube, (see 

 figure 6) entering through a narrow, curved inlet tube, in which 

 the soil sample is kept agitated by the current itself. The 

 objection to this plan is twofold : first, the narrow, curved 

 inlet-tube is readily clogged by the soil mass at the lower 

 velocities, which are thereby changed, so that, unless a very 

 small amount of soil only is employed, the whole mass is not 

 kept properly stirred ; second, the circulating currents brought 

 about by the conical shape of the tube cause the sediment-par- 



FK.. 7. The Churn Klutri.itor i Hilgnrd's) for the physical analysis of soils. 



tides t<> coalesce into complex, larger ones (floccules). which 

 will then settle down rind fail to pass over at the current- 

 velocity corresponding to their individual component parts. 



Churn l : Jiitn\it<' ;^//// Cylindrical Tube. The errors just 

 alluded to are obviated by an arrangement devised by the 

 writer, in which a rapidly-revolving ^tirrer. placed at the base 

 of a cylindrical tube in which the washing process is conducted 



