EFFECT OF ALUMINA ON DEVITRIFICATION OF SODIUM OXIDE-DOLOMITE LIME-SILICA GLASSES*

The effect of the substitution of A1₂O₃ for the oxides of sodium, silicon, calcium, and magnesium in the ratio in which they occur in dolomite on the liquidus temperatures and phase relations for glasses lying within the composition range, Na₂O 12 to 16%, CaO-MgO 0 to 20%, SiO₂ 63 to 78%, and A1₂O₃ 0 to 10%, has been determined. The results on 116 individual determinations are given. Devitrite is the primary phase in very few glasses. Several glasses were found which cannot be devitrified. A comparison of devitrification temperatures of calcite and dolomite-lime glasses is made.