Grain-Size Analysis of Soil (Including Both Mechanical and Hydrometer Analyses) - Soil Properties: Testing, Measurement, and Evaluation - page 118

Grain-size analysis for these soils is done, therefore, by another
method—hydrometer analysis. The hydrometer method is based on
Stokes' law, which says that the larger the grain size, the greater its set-
tling velocity in a fluid.
If a soil sample contains both large and small particles, which is
often the case, its grain-size analysis can be performed using a combi-
nation of the two methods described.

Sieves (see Figure 10-1)
A full set of sieves includes the following sizes [1]:
3 in. (75 mm)
2 in. (50 mm)
1 1 ⁄ 2 in. (38.1 mm)
1 in. (25.0 mm)

APPARATUS
AND SUPPLIES

⁄ 4 in. (19.0 mm)

3

⁄ 8 in. (9.5 mm)
No. 4 (4.75 mm)
No. 10 (2.00 mm)
No. 20 (0.850 mm)
No. 40 (0.425 mm)
No. 60 (0.250 mm)
No. 140 (0.106 mm)
No. 200 (0.075 mm)

3

A set of sieves that gives uniform spacing of points for the grain-
size distribution curve to be prepared may be used. It consists of the
following sizes [1]:
3 in. (75 mm)
1 1 ⁄ 2 in. (38.1 mm)
3 ⁄ 4 in. (19.0 mm)

Figure 10-1
Set of Sieves