AbstractReactions of sodium carbonate with quartz occur without fusion between 726° and 805°C. When the reactions are conducted in a stream of nitrogen, the size of the charge, composition of the mixture, rate of flow of gas, and duration of reaction have appreciable effect on the reaction rates and on the nature of the product.In presence of sufficient sodium carbonate, the end product of the reaction at the higher temperatures is the orthosilicate. The formation of a series of silicate ions as rntermediate products between the metasilicate and the orthosilicate by interaction of the former with carbonate ions is postulated. This process is considered to be reversible with the smaller silicate ions. This theory, moreover, serves to reconcile several apparent anomalies in the experimental data.The rate of reaction of thc silica particle is not measured by the rate of carbon dioxide evolution.