(Chemical symbol P) Element No. 15 of the periodic system; atomic weight 30.98. Non-metallic element occurring in at least three allotropic forms; melting point 111 (degrees) F.; boiling point 536 (degrees) F.; specific gravity 1.82. In steels it is usually undesirable with limits set in most specifications. However, it is specified as an alloy in steel to prevent the sticking of light-gage sheets; to a degree it strengthens low carbon steel; increases resistance to corrosion, and improves machinability in free-cutting steels. In the manufacture of Phosphor Bronze it is used as a deoxidizing agent.