of 0.01 g. The simplest procedure for determining size distribution is to 

 hand sieve small samples that have been washed and dried in the oven. 

 Although hand shaking normally does not provide a complete separation, espe- 

 cially in the finer size ranges, it is considerably more accurate than visual 

 estimation. A recently developed device that effectively shakes down the 

 material, yet is small enough to be readily portable, uses sonic vibrations to 

 agitate a stack of graduated sieves and thus promote downward flow. Results 

 of this method are comparable to standard sieving methods using large mechani- 

 cal shakers. The sonic vibrator, oven, and balance are all small and light 

 enough to be set up on a table and operated in a motel room or similar small 

 space and can be readily transported and set up for operation in new locales 

 as the survey base is changed. 



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