From the introduction: A water separation, or flotation, machine is an instrument that divides soil into three components: the material that floats (called flot or light fraction), the stones and other heavy portions that do not float (called residue or heavy fraction), and the particles that either dissolve in water or become suspended in it and are washed away. The primary purpose for utilizing such a device is the recovery of organic remains, such as charred seeds, charcoal, or small bones, which would otherwise be permanently lost. However, the machine is of great value for archaeological...