Figure 2 – Graph of MgO versus P2O5 for the soda-lime-silica glasses
Figure 2 shows MgO plotted against P2O5 concentration only for the soda-lime-silica glasses. By reporting in similar graphs also the concentrations of Na2O, Al2O3 and K2O, four subgroups were identified, arbitrarily labelled Na1, Na2, Na3 and Na4. Group Na1 corresponds to natron glass, while the differences in the other three types of glass can be attributed to their having been made from different soda plant ash.
