a nonmetallic element used to manufacture phosphoric acid in phosphor bronzes incendiaries pyrotechnics matches and rat poisons the white or yellow allotrope is a soft waxy solid soluble in carbon disulfide insoluble in water and alcohol and is poisonous and self igniting in air the red allotrope is an amorphous powder insoluble in all solvents and is nonpoisonous the black allotrope comprises lustrous crystals similar to graphite and is insoluble in most solvents