THE MECHANICAI, ANALYSIS Ol' Alill) SOILS 



39 



in our liands, identical witli those in whicli tlie tive or ten minutes preliminary puddling 

 was carried out, but the clay comes away more slowly. 



The soil need not usually remain in the shaker more tlian about an hour, as will 

 be seen from the results of the following experiments with a soil containing about 

 54 per cent, of clay. 



With the majority of soils little appears to be gained by continuing the operation 

 beyond an hour, since the small amount of clay which remains unaffected at the end 

 of that period is easily brought into suspension by the short puddling mentioned. 



Centrifugal Method 



While the method of separating the clay, as outlined above, is rapid and generally 

 satisfactory, the operation may be performed still more quickly by means of the 



centrifugal machine, .^gainst this must be stated the fact that the centrifugal method 

 entails much more of the operator's attention, though the use of an alarm clock which may 



