Calibration of the - 3 - D. M. Poole end 



Emery Settling Tube W. S. Butcher 



for Scind Analysis 



It was found thct the settling tube r-nnlyses for materiel b etween 0.062 

 tJid 1 inm. had a reproducibility or probable error in medirn diameter of 0.8%. 

 For the stine sand the sieving probable error was found to be 0,1%. The method 

 is thus approximately as accurate as sieving. The errors occurring during 

 splitting of the sample to the proper size were investigcted by several proce- 

 dures, but the results are not conclusive. The maximum splitting error was 

 6.2%. The effect of mr.teriel finer than 0.062 mm. in the sample was investi- 

 gated and it was found that no significant difference was produced where the 

 fine material was 5% or less of the total. The effect of material coarser 

 than 1 m.u. in the sample was also investigated and it was determined that all 

 coarse material should be removed before analysing. 



A recomiaended procedure to be followed in making such an analysis is in- 

 cluded . 



Introduction 



Einery (1938) described c rcpid and accurate instrument for the mechanical 

 analysis of material of sand size. In the original paper there was not suffi- 

 cient information to indicate the accuracy of the method nor procedure to be 

 followed in making an analysis. This paper further confirms the reproduci- 

 bility of the results obtained from the settling tube, the close correlation 

 with sieve analysis, and gives a detailed recommended procedure. The equiva- 

 lent diameters obtained by this method would appear to be more indicctive of 

 erosional and depositional featxires than those obtained by sieving, particu- 

 larly where there is a high percentage of micaceous or plrty material. The 

 time saved by this method over dry-sieving is of great advantage where there 

 ere numerous samples to be analyzed. 



The Emeiy Settling Tube is essentially a glass tube of 21 i.Ei. inside 

 diameter and I64 cm. length. At the bottom the tube narrows to 7 mm, inside' 

 diameter and is closed with a stopcock. The narrow portion of the tube above 

 the stopcock is engraved with milliliter divisions on which to read the cumu- 

 lative heights of sediment. Emeiy (1938) gives a figure of the settling tube 



