What is "phosphorus sesquisulfide"

Phosphorus sesquisulfide is the inorganic compound with the formula . It was developed by Henri Sevene and Emile David Cahen in 1898 as part of their invention of friction matches that did not pose the health hazards of white phosphorus.1 This yellow solid is one of two commercially produced phosphorus sulfides. It is a component of "strike anywhere" matches.

Depending on purity, samples can appear yellow-green to grey. The compound was discovered by G. Lemoine and first produced safely in commercial quantities in 1898 by Albright and Wilson. It dissolves in an equal weight of carbon disulfide (CS). Unlike some other phosphorus sulfides, PS is slow to hydrolyze and has a well-defined melting point.