Use
Phosphorus trioxide reacts exothermically with bases. Melted Phosphorus trioxide readily ignites in air. Instantly ignites with a flame of almost blinding brilliance when thrown into oxygen at 50-60°C [J. Am. Chem. Soc. 125:347. 1924]. Incompatible with ammonia, disulfur dichloride, halogens, oxygen, phosphorus pentachloride, sulfur, sulfuric acid, water [Bretherick, 5th ed., 1995, p. 1778].