Wiktionary
phosphorus pentoxide
n. (context inorganic compound English) the compound, P2O5, formed by the spontaneous combustion of white phosphorus in air; it reacts violently with water to form phosphoric acid and is used as a powerful desiccating agent
Wikipedia
Phosphorus pentoxide
Phosphorus pentoxide is a chemical compound with molecular formula P O (with its common name derived from its empirical formula, PO). This white crystalline solid is the anhydride of phosphoric acid. It is a powerful desiccant and dehydrating agent.
Usage examples of "phosphorus pentoxide".
Penton bent over his pile of magnesium metal, and a moment later a terrific flare of blue-white light glared through the enveloping pall of phosphorus pentoxide smoke.