It is an alternative to reheating prepackaged meals in a microwave oven. In the processing of glass-ceramics, molten glass is cooled down gradually before reheating and annealing. They are not used for cooking or reheating food. This prohibition of reheating liquids only applies when the liquid has completely cooled. Chilled ready meals are intended for immediate reheating and consumption. Laura Miller of Salon.com called "Spawn" "a witless exercise in reheating leftovers". The steps that follow involve reheating, regrinding and finally gathering the powder in a pan. A typical practice of reheating the sausage is to just fry it in a pan. This cools the blood heading to the testes, while reheating the returning blood. Its distinct colouring develops with applied reheating and cooling. This reheating time varies depending on the battery-pack temperature, and power available for reheating. Magnetic monopoles may also have been produced thermally after inflation, during the period of reheating. The idea behind double reheating is to increase the average temperature. William Wilkinson of Wigan patented the exhaust steam reheating system about 1881. Today, double reheating is commonly used in power plants that operate under supercritical pressure.