| Abstract: | The addition of small amounts of iron oxide (0.1 to 0.2%) to soda-lime-silica glass batches exerts a profound influence in increasing the output of glassmelting tanks as well as in favoring the production of higher quality glass. The color produced by this addition, moreover, is not objectionable for many uses of the ware. The accelerated melting rate probably is the result of a chemical effect of iron oxide in the batch and a physical property possessed by such glass to absorb radiation from the flames more efficiently. Attempts to measure these effects were made by rioting the melting rate of glasses which contain varying additions of iron oxide and by determining the temperature gradient that exists in glass when it is melted in a miniature tank. The presence of iron oxide aids melting and fining in crucible melts at 1200°C., but no effect was observed at higher temperatures. The measurement of temperature gradients in a pot holding 45 lb. of glass and heated by flames passing over the glass surface showed that the temperature gradient increases with iron oxide content. |
