The time dependences of density and surface tension are presented for iron-carbon melts. Oscillating character of these dependences is revealed. Polytherms and isotherms of properties as well as calculations, executed on their basis, for adsorption and other physicochemical characteristics of the melts testify a microheterogeneous structure and its strong dependence on a temperature. Surface layer and bulk compositions are almost identical and come close to composition of cementite with carbon concentration rise.