Many front loading machines have internal electrical heating elements to heat the wash water, to near boiling if desired. The rate of chemical cleaning action of the detergent and other laundry chemicals increases greatly with temperature, in accordance with the Arrhenius equation. Washing machines with internal heaters can use special detergents formulated to release different chemical ingredients at different temperatures, allowing different type of stains and soils to be cleaned from the clothes as the wash water is heated up by the electrical heater.