Calibrrtion of the - 4- - D. M. Poole end 



Efaery Settling Tube W. S. Butcher 



for Siind Analysis 



used by him; the one in present use is sioil&r. 



The aisi of the investigetion was to deteraine the probable errors inher- 

 rent in the method, to determine the splitting errors encountered in preparing 

 the sf'jnple, to evaluate the effects of particles greater than 1 ma. end less 

 than l/l6 ram. in diameter, to evaluate the effect of the weight of the sample 

 used, and to compare the settling tube cjialysis with that obtained usii:ig 

 standard sieves. These effects are discussed separately in the following sec- 

 tions. A recommended procedure to be followed in making an analysis by this 

 method is given at the end of the paper cuid is based on experience gained in 

 using the settling tube and the results of this investigation. 



Method of Investigatio n 



The Emery Settling Tube was used, in all the tests, in the manner outlined 

 in the section entitled "Procedure." Briefly, this consists of splitting the 

 bulk sample to 3.5 - A. 5 grams, introducing this small sample into the Emeiy 

 settling tube, and reading cumulative heights at times corresponding to the 

 settling time for a given size material in distilled water at the observation 

 temperature (see sample data sheet, fig. 1). For purposes of comparison, a 

 sieve analysis was made in certain cases using the Tyler Standard Screen Series. 

 The shaking time for the sieve analysis on a mechanical shaker was 10 minutes. 



The ciomulative volume percentage for each grade of the Emery settling tube 

 and the cumulative weight percentage for each grade of the sieve analysis were 

 plotted on logarithmic probability paper. From such a plot the median diameter 

 (50 percentile) was read, VJhere required for comparison with other tests, the 

 standard deviation of the median {<$ - ^ (Dev. of Mdj j ^^^^ obtained and from 



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