"[P]lants were supplying a lot of chemicals during antiquity and even during our Middle Ages in Europe. ...If we look... at the results of the burning of wood or plants, ...we get plenty of SiO2... plenty of CaO () in beech, oak, acacia, palm trees. Plenty of alkali (K2O) in fern and bulrush... which means I am claiming... [the Egyptians] used the plants and the woods in the manufacture of these ashes... the sources of their chemicals."