The Lowe process is performed in a series of three chambers, the generator, the carburettor and the superheater. The original air blast is used to produce air gas in the generator. The heat of primary combustion heats the coal sufficiently, while the air gas is burned by a second air blast in the other two chambers in which the oil for carburetting is decomposed. These chambers contain a quantity of loose fire brick called "checker work," and the air gas is burned in them during the time the air blast is on the main producer. When the coal and checker work are hot enough, the air blast is shut off and the steam blast is turned on. Heat stored in the checker work pyrolyzes the mixture of water gas and oil, which is led through the chambers while the steam blast is on the producers. The Lowe process is endothermic, and cools the generator and checker work, so the process has to alternate between air blast for heating and steam blast for gas production.