Sodium sulfide has a number of uses. The most extensive use is in the deplilation of hides for leather before tanning, in wood pulp processing and desulfuration of rayon and cellophane. It is also used in the manufacture of polymers, elastomers, lubrication oils, and organic compounds. It is used as a reducing agent and in ore flotation and in the recovery of metals as the insoluble sulfides. A recent development has been in the development of scrubbers for the capture of oxides of nitrogen from gases.