Caly minerals absorb water because of their hydration-activation centers. Bonding water is one of important factors which control the physico-chemical properties of viscous clays' thickness, plasticity, dispersion, swelling and shrinking as well as strength and deformability, which strongly pins down the development of those trades dealing with clay minerals. The quantitative analysis of water on clay minerals and clear description of the hydration mechanism are the study of the essential theory ...