The extensive internal surface in a wad of clay, combined with the surface activity of individual particles determines its high adsorbity power, which is particularly evident in its behaviour with respect of water. Dry clay takes up water from the atmosphere in proportion to the extent of its internal surface which inturn depends on particle size distribution.
On storing over water in a damp saturated atmosphere, certain clays took up so much water in the course of a year that they became completely plastic. Permeability to water, a factor of much importance to ceramic industry can be studied by measuring the quantity of water that could be forced by unilateral pressure through a cake of moist kaolin held between two filter cloths.
To be contd………..
