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A non-metallic chemical element (?), symbol P, atomic weight 31, occurring extensively in nature, always in combination, and in many animal tissues-bone, muscles, and nerves. It comes usually in sticks, colorless, of soft solid consistence, with lustrous cut surface; it has a great affinity for oxygen, inflaming in the air at a temperature only a little above 100° F. and burning with an intensely bright light and great heat; at ordinary temperatures it oxidizes slowly, being luminous in the dark. It occurs also in an allotropic form as amorphous or red p. (see below). Phosphorus is exceedingly poisonous, causing intense inflammation and fatty degeneration; inhalation of the fumes by workers in phosphorus may cause necrosis of the jaw (phossy jaw). It is employed in the treatment of rickets and other conditions of malnutrition of the bones, and in neurasthenia and sexual impotence, in doses of gr. 1/100 (0.0006).