Hydrometer, sedimentation jar, balance, stopwatch.
- A 50gm soil sample is used which is passed through sieve#200.
- The soil sample is mixed with distilled water in a beaker to form a smooth thin paste.
- To have proper dispersion of soil, 8gm of sodium hexameta phosphate is added to the solution per 50gm of soil sample.
- The solution is passed in sedimentation jar. Then it is shaken vigorously while kept vertical.
- The stopwatch is started and the hydrometer is slowly inserted in the jar and readings are taken at 2, 3 and 10 minutes interval.
- The diameter of grains and the %age passing is calculated by using formulas and plotting a curve
- The soil suspension is opaque, so take the readings corresponding to the upper level of meniscus.
- The time interval between readings should be such that the hydrometer is stable at the time of next reading
Observations & Calculations:
|Time(min)||Hydrometer reading, Rh and the neck of the bulb(H) (cm)|| Effective depth(He)