Particle density (Helium-pycnometer)

To determine the volumetric mass of the solid particles in the soil a helium-pycnometer is used. The sub-sample is placed in a chamber of known volume, which is maintained at a certain constant temperature, after which helium is added into the chamber. The resulting pressures will eventually reach an equilibrium, which are then used together with the ideal gas law to determine the apparent density of the particles.