The density, surface tension, & viscosity of the melts from the PbO-B2O3-SiO2 system have been measured at temperatures in the range 1073-1473K. The effect of composition on these properties was also investigated. Density of the melt was found to increase linearly with increasing PbO content. Molar volume was derived from the density data, & its deviation from the additivity of partial molar volumes was calculated. These deviations in molar volume from those obtained from additivity rules have been used along with the ratio of various coordination numbers of boron (as reported by Bray) to discuss the structure of the melts. The surface tension was found to decrease with decreasing SiO2/B2O3 ratio, & to increase in the range of the PbO content between 30-60 mol%, showing a maximum at ~60 mol% PbO, & then decreased with further additions.
