Using the maximum bubble pressure method of density determination, the density-composition relationship of iron silicates in contact with solid iron at 1410°C has been determined. The "iron oxide" in an iron silicate has been replaced by calcium oxide, manganous oxide, cobaltous oxide, nickel oxide and calcium fluoride and the density-composition relationships occurring have been obtained. The calculated oxygen density-composition relationships have been interpreted in terms of the effects of silica concentration and cationic species on the anionic configuration occurring in the melts and this interpretation has been correlated with recently-developed thermodynamic models of silicate anion configuration in basic binary silicate systems. / Thesis / Doctor of Philosophy (PhD)