Specific Gravity Method

Specific Gravity is the ratio of the weight of a given volume of a material in air at a standard temperature to the weight in air of an equal volume of distilled water at the same temperature.
Pycnometers can be used to test a wide range of materials from clay to sand and gravel, smaller than 10mm.

pycnometer Image
Consists of a 1kg glass jar with brass cone, locking ring and rubber seal.