Silica gel is a substance that is capable of absorbing water vapor from the atmosphere. The silica gel filled cartridges are used in desiccators and desiccator cabinets for drying air and gasses. Place the cartridge in the cabinet to be dried and check occasionally to observe a color change.
The color of the silica gel is blue, as received, and will turn pale pink on absorption of water vapor. The dish containing the gel is polystyrene with a porous membrane on top of the gel.
After saturation, the spent gel crystals can be regenerated by heating the cartridge in an oven at 50°C overnight. If more rapid drying is needed, it will be necessary to take the gel out of the polystyrene dish by slitting the membrane and pouring the gel out into a heat resistant dish for oven drying at 150°C. The polystyrene will not withstand more than 90°C.
Silica gel is inert, non-toxic, non-corrosive and non-melting.