Theoretical Drying capacity of CaSO4
The actual drying agent is calcium sulfate semihydrate. It has low drying capacity, which decreases already after the uptake of $6.6\%$ water (theoretical maximum is $15.7\%$). Within these limits, however, it is possible, for example, to dry air at room temperature down to $0.0004\ mg$ of water per liter of air. It is suitable for drying almost all liquids and gases. It can be regenerated by heating to $190-230^{\circ}C$. Above $300^{\circ}C$ it loses its drying properties. The data comes from an old Merck's handbook on drying agents.