Phosphorus Pentoxide: Phosphorus Burned in a Stream of Dried Air

Phosphorus pentoxide is what phosphorus becomes when it burns completely: a white powder that grabs water so hard it is the best drying agent known. Thorpe's Dictionary (1913) gives the way to make it pure: burn phosphorus in a dish inside a three-necked glass globe while dried air is drawn through, dropping in more pieces as it burns. It must be kept from damp, which turns it to phosphoric acid. White phosphorus is poisonous and catches fire in air. The picture: our diagram.