Abstract: An article for use as a solution releasing control device in a fluid conting medium, such as air containing water vapor, is provided including an inner material composed of solid substance capable of sorbing this fluid and also capable of dissolving in this sorbed fluid, for example a hygroscopic, deliquescent agent such as lithium chloride or a mixture of lithium chloride and the tetrasodium salt of ethylenediaminetetraacetic acid. This inner material is enclosed in a container fabricated of a material which is substantially impermeable to the fluid in the medium surrounding it and is substantially nonwettable by the solution formed from the sorbed fluid and the sorbing agent, for example an essentially hydrophobic film, such as polyethylene. The container is provided with perforations of pre-determined number and size to provide an accurately controlled fluid sorbing and solution releasing device.