The particle-size distribution is one of the most important physical qualities of soil. The division of soils (soil classification) is primarily based on particle-size distribution. When accurately determining the particle size in samples, in addition to the determination using sieves, other methods will need to be applied. A simple method for the determination of the particle size is the pipette method. After carbonates, organic substances and possible iron oxide have been removed (because of their binding function) the pipette method is used to determine the fractions of particles smaller than 38 μm.