• Sand is type of soil – Clay is another type of soil. Slit is another type of soil (All are based on his size)

• But sometimes this three parameter of soil take together.

• Suppose I take any soil from site always you find that thereis above three particles.

• Soil Classification is the first step.

• Developed a site or area, see the soil.

• Sampling, testing (Grainsize, proportion)

• For Classification purpose there are certain test that you can do in lab itself, but suppose onsite no any equipment and you have to give some qualitative idea what type of soil it is?

Calibration of Hydrometer :-

He=(H+h/2)-Vh/A+Vh/2A---------(a) Where H= Depth from the free surface B’-B’ to the lowest mark of the stem. And h = height of the bulb VH=Volume of hydrometer. A= Cross-sectional area of jar.

In Eq. (a) it has been assumed that the rise in suspension level from A-A to A-A’ at the centre of the bulb is equal to the half the total rise due to the volume of the hydrometer.

Thus ,

$He=H+1/2(h-VH/A)$

Corrections applied to the hydrometer Reading.

1. Meniscus Correction
2. Temperature Correction
3. Dispering agent Correction
4. Composite Correction