Helium solubilities have been measured in sodium silicate glasses at 500 deg C and in melts at 1420 deg C using a saturation outgassing method. Measurements over the temperature range from =200 to 1500 deg C were made for the 20Na20.80Si02 composition. Helium solubilities in the glasses at 500 deg C and in the melts at 1420 deg C decrease with increasing concentration. The compositional dependence of helium solubility is greater in glasses than in the melts. The data for the 20Na20.80Si02 composition indicate that the solubility of helium decreases with increasing temperature for the glasses, passes through a minimum in the glass transformation range and then increases with increasing temperature for the melts. The results are discussed in terms of the effect of composition and temperature on the free volume of these materials.
