Abstract
Reaction between water and sodium borate glasses containing 5–33.3 mole per cent of Na2O was studied at various temperatures ranging from 4°C to 29°C and the amounts of Na2O and B2O3 extracted were determined by titrametric methods. The amounts of Na2O and B2O3 extracted were found to bear a linear relationship with time from the beginning of the reaction at all temperatures. The ratio of the constituents in the extract from the glasses containing 10 to 33.3 mole per cent of Na2O were found to be the same as that in the glasses indicating that the glasses dissolved as a whole. The activation energy of the extraction process showed a maximum in the region of 15 to 20 mole per cent Na2O which corresponds to completion of tetrahedral co-ordination of boron.

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