ENTHALPIC ANALYSIS OF MELTS IN THE CA2MGSI2O7-CASIO3 SYSTEM

Relative enthalpies of the Ca2MgSi2O7-CaSiO3 system melts have been me asured by combination of high-temperature drop calorimetry and solutio n calorimetry of the same sample in the temperature interval 1760-1930 K. From these results, the relative enthalpy-temperature-composition relation has been found by regression analysis. The enthalpy of mixing of melts is zero at any composition within the experimental errors of measurement. The heat capacities of melts do not depend on temperatur e and are a linear function of composition. They are discussed with va lues calculated employing Stebbins et al.'s, Richet and Bottinga's, an d Lange and Navrotsky's models.