Based on an example of the dissolution process of calcium apatites, a new chemical approach to elaboration of basic dissolution mechanisms of inorganic solids in liquids at the atomic (ionic) level has been proposed and discussed The approach is based on experimental results on the surface state analysis, passed through the logic of chemical equations, and describes the dissolution process as a sequence of the successive chemical reactions occurring on the solid — liquid interface. According to the approach elaborated, the chemical mechanism of apatite dissolution appears to be incongruent (non-stoichiometric) at the atomic (ionic) level.