US Patent 7323035 Dehumidifying device

A dehumidifying device for absorbing water vapour from ambient air comprising a container having an opening to permit water vapour to enter the container, the container having a water-absorbing agent disposed therein for absorbing water vapour, wherein a first portion of the water-absorbing agent is adapted to provide an indication of water absorption faster than a second portion of the water-absorbing agent following exposure of the first and second portions of water-absorbing agents to water vapour, thereby providing an early indication of the operation of the device.