Anhydrous magnesium sulfate is a magnesium containing compound with the molecular formula MgSO4. Anhydrous magnesium sulfate is a common chemical reagent and drying reagent. However, magnesium sulfate often refers to magnesium sulfate heptahydrate, because it is not easy to deliquesce and is easier to weigh than anhydrous magnesium sulfate, which is convenient for quantitative control in industry.