FUNDAMENTAL REACTIONS IN GLASS MELTING. (1)

Abstract

Thermal decompositions of the raw materials of glass, were studied with a thermobalance.
With certain batches, the decrease of weight due to the liberation of gaseous components were determined after heating at 700°, 800° and 900°C for 2 hours. The amounts of alkali extracted by hot water were measured on the same samples.
Batches, whose compositions were (Na₂ or K₂) CO₃, 0.5 (Ca or Mg) CO₃, 3 SiO₂, gave off almost all the carbon dioxide contained in them below about 900°C.
When 1/4 part of (Na₂ or K₂) CO₃ was replaced by the equivalent amount of (Na or K) NO₃, the liberation of gas from the batches was remarkablly accelerated, and the amount of alkali extracted by hot water was decreased at the same time, namely, the reaction was acceleratrd at least below about 900°C