58 THE MECHANICAL ANAL YSIS OF SOILS [chap. 



liquid is poured 



The operations 



sediment settles 



the liquid above 



for some time and revveighed, to obtain the weight of the 

 "clay" after ignition. 



4. The sediment from which the clay has been 

 removed is worked up as before in the beaker, which, 

 however, is now only filled to the depth of 7-5 cm. 

 The contents are now allowed to stand for twelve 

 and a half minutes only, when the 

 off into a large jar as before, 

 are then repeated until all the 

 in twelve and a half minutes and 

 is left quite clear. The contents of the jar are now 

 evaporated to dryness and weighed, as in operation 

 3, before and after ignition ; this fraction is desig- 

 nated "fine silt," and lies between o-oio and 0-002 mm. 

 in diameter. 



5. The sediment remaining in the beaker is worked 

 up afresh just as in the previous operations, the mark 

 being now placed 10 cm. from the bottom of the beaker, 

 and the time of settlement fixed at one hundred seconds. 

 The sediment is dried and weighed as " fine sand," while 

 the portion that is poured off is obtained by evaporation 

 as in the previous operations, and is designated as " silt." 

 The soil has thus been divided into the following series 

 of fractions : 



