Pycnometer Method

• This is also a quick method for the determination of the water content of soil whose specific gravity G is accurately known. The pycnometer is a large size density bottle of about 900ml capacity. 

Procedure: 

• A clean, dry pycnometer is taken and its weighed along with its cap and washer is found (M1).

• A wet soil sample of about 200-400 g is taken in the pycnometer weighed along with its cap and a washer is found (M2).

• Now, the pycnometer is filled with water up to half its height and mixed thoroughly with a glass rod to eliminate any air present in the voids of the soil sample collected. Stop stirring when air bubbles are not forming which indicates the presence of no air in the voids.

• Then the pycnometer is completely filled with water up to the conical hole in its cap (brim). Wipe and dry the pycnometer from the outside and weigh it .

• Now empty the pycnometer and clean it thoroughly from the inside.

• Then fill the pycnometer with only water up to its brim and weigh it .