The term "hydrated sodium carbonate" is commonly used to encompass the monohydrate (NaCO·HO), the decahydrate and the heptahydrate (NaCO·7HO), but is often used in industry to refer to the decahydrate only. Both the hepta- and the decahydrate effloresce (lose water) in dry air and are partially transformed into the monohydrate thermonatrite NaCO·HO.