The use of nonaqueous solvents has many adventages in analytical chemistry especially in acid-base titrations. The number of methods based on redox reactions in nonaqueous solutions is negligible relative to that of acid-base determinations and the chelatometric titrations (e.g. those of metal ions in dimethylformamide with EDTA) are of little practical importance. Since several basic bases and acids can be found in pharmaceutics nonaqueous titrations are generally used for their determination. At the same time the interpretation of these reactions is rather incosistent the theories and suppositions of the 1920s and 1930s are applied and sometimes confused. For example one of the most popular textbooks on analytical chemistry discusses the topics of nonaqueous madia on the grounds of the so-called solvent theory. As it will be treated in this paper this theory can be easily understood explains the promoting (and leveling) effect but not applicable to the differentiating effect.