Effect of water dissolution in melt on melt endmember component activities: An increasing weight percentage of water in a melt leads to a decrease in the activities of the different endmember components. However, this change in activity is too small to have an effect on the outgassing of the vapour species that is detectable in thermal emission spectra. Sossi et al. (2023) was used to estimate the solubility of water in silicate melt.