ABSTRACT
Sedimentation ranks with sieving as one of the oldest methods of particle size measurement and classification, and for many years was an extremely important technique. A wide range of instruments were produced, using principles such as x-ray or optical absorbance to detect the suspended material, and centrifuges to accelerate the process or to extend its range of application. Unfortunately many of these instruments have been displaced in recent years by light scattering methods, which are often more rapid and convenient, and many older sedimentation instruments are no longer manufactured or supported. This is unfortunate because sedimentation methods are capable of providing accurate results with good size resolution. They are particularly valuable for users who perform few analyses and cannot justify the cost of the more expensive light scattering instruments. They are also among the few methods that can be used for hands-on teaching in large classes, since the cost of simple sedimentation columns is relatively low.
