There are many cases when the identification of clays is important. A comparison of clay layers within a sedimentation basin and an investigation of clay content in ancient ceramics are typical examples. Systematic investigations in specially equipped laboratories have given promising results in connection with the comparison and identification of clays. Various methods for clay analysis are described in this paper. Of special interest is the possibility of relating the clay contents of ceramic artifacts to local clay deposits. See also 20-32. -- AATA