Calibri'-tion of the - 11 - D. M. Poole and 



Ea^-iy Settling Tube W. S. Butcher 



for Sand /inalysis 



Procedure. 



The preparation of sojnples for analysis is discussed at length in Krum- 

 bein and Petti John (1938). The only procedures considered in this paper are 

 the preparation of samples for analysis by means of the settling tube, and the 

 method for running the seinples through the tube. 



Splitting the Sample ; The sample after disaggregation is first passed 

 through a 1 mm. sieve to remove all particles greater than 1 mm. The percent 

 by weight of the sainple greater than 1 im, can then be calculated. If there 

 is more them. 5% material less than l/l6 mm. in the sample, it should be re- 

 moved by wet sieving. Then the percent by weight of the sample less than l/l6 

 ram. can be determined. 



The sample is next split to a weight of approximately 3.5 - 4.5 grojns for 

 the settling tube analysis. A Jones type sample splitter was used to split 

 the sample down to a weight of about 20 - 25 grams. The "Otto Microsplit" was 

 used to split the sample further to the correct weight for analysis (see above) 

 by the settling tube. This change of splitters is merely a matter of conven- 

 ience in handling the sample. Tests showed that the type of splitter used, 

 introduced no appreciable error in the analysis. 



Method of Introducing Sample into Tube ; The method has been somewhat mod- 

 ified from that recommended by Emery (1938). A centrifuge tube (2.75 x 13.5 

 cm.) with its bottom cut off is used as an introducing tube. The bottom of tho 

 tube is closed by the thumb, the sand poured in and distilled water added by 

 means of a wash bottle so as to remove the greins sticking to the sides of the 

 introducing tube and to cover the sand about 3/4 of <?ji inch. The sand is 

 stirred thoroughly until no bubbles remain, and any prrticles floating on the 



