Volatilisation From Soda-Lime-Silica Melts At One Atmosphere And Reduced Pressures

Volatilisation losses from three Na2O-CaO-SiO2 melts have been measured in vacuum at 1100-1300 deg C and at 1 atm and 1400-1450 deg C. Two were simple Na2O-CaO-SiO2 compositions with 16.0 and 20.7 wt% Na2O, the third had 20.3% Na2O and 1.7% Al2O3. Losses of Na2O were at least for the lowest alkali content and greatest for the highest but differed much more than the ratios of the alkali contents. Loss at 10-4 to 10-5 atm was 100 to 300 times greater than at 1 atm. Losses at 1 atm were appreciably altered by a small change in furnace construction.