Cappella di San Filippo

Inside the chapel of San Filippo, there are unique frescoes, renowned for their peculiarity and extraordinary beauty. The fresco above the altar depicts the Holy Spirit using a dove surrounded by angels emerging from the clouds. The angels, originally rosy, are now darkened due to the chemical transformation of white lead, a white pigment that was frequently used until the twentieth century. White lead is a basic lead carbonate and over time it has been discovered that the outer layer, interacting with substances present in the air, is transformed into lead sulfide which has a very dark color. Air pollution has therefore altered the work, making the angels almost black and the Holy Spirit more like a blackbird than a dove.