A sand bath is a common piece of laboratory equipment made from a container filled with heated sand. It is used to provide even heating for another container, most often during a chemical reaction. A sand bath is most commonly used in conjunction with a hot plate or heating mantle.
A water bath is laboratory equipment made from a container filled with heated water. It is used to incubate samples in water at a constant temperature over a long period of time. It is also used to enable certain chemical reactions to occur at high temperature.