The medieval stained glasses of Pisa Cathedral (Italy): their compositions and alteration products.

X-ray microanalysis and infrared spectroscopic investigations of some coloured panes of the mediaeval stained-glass windows of Pisa Cathedral have provided information regarding their composition and alteration products. In particular, this study has revealed the existance of both potash and soda glasses, which were altered in two distinct ways. A comparison with a coeval glass belonging to a church in Bologna is reported.