310 Mechanical Anah/'n's of Soils and other DinpevHlmis 



concentrations, A^, A^, A^. etc., respectively such that "ZA = C'^, the 

 total concentration. Then if the fractions settle independently of each 

 other, each fraction will behave as a separate column uniform in con- 

 centration from top to bottom and we may represent the state of affairs 

 at the beginning of sedimentation as in the upper diagram of Fig. 1, 

 the relative amount or partial concentration of each fraction being 

 represented graphically by the thickness of its column on the diagram. 



b 



{ 



B 



Fig. 1. Diagrammatic representation of sedimentation. 



As sedimentation proceeds each column will fall bodily at its own 

 appropriate velocity and the disposition after settling has proceeded for 

 a certain time may be represented by the lower figure of the diagram. 

 The black portion below the line CD will represent the amount of each 

 fraction accumulated on the bottom of the sedimenting vessel, while 

 the concentration of the suspension at any depth will be given by the 

 total width of columns at that depth. Thus at depth d, the concen- 

 tration will be equal to the sum of the partial concentrations of the 



' Or Zi.-l + organic n\nftpr = C in the rase of nrdinarv Hiiila. 



