326 



The Shrinkage of Soils 



Especial interest centres in the point at which the curve cuts the 

 vertical ordinate ; this occurs when the value of the linear shrinkage is 

 equal to 23-5 per cent. At this point the pore space will possess a 

 value of zero. Now if it is assumed that the physical condition of 

 pure dried colloidal clay approximates to that which occurs in con- 

 tinuous matter (such an assumption being presumably justifiable since 

 the dimensions of colloidal particles though considerably submolecular 



30 



25 



20 



5 15 



:! 10 



5 10 15 20 25 30 



Pore spare per cent, on rontracted bricks 



Fig. 4. 



nevertheless commence to approach the molecular order of magnitude), 

 we arrive at the figure obtained by extrapolation as a possible limiting 

 value for the shrinkage of pure colloidal olay. 



Such an assumption can only be regarded as approximate since the 

 distance through which the curve has been extrapolated is considerable ; 

 on the other hand by utihsing the value so obtained it is possible to 



