Abstract: The invention provides active polymeric phosphorus nitrides containing hydroxyl and halogen. The halogen atoms and hydroxyl groups are linked to phosphorus, and the nitrides contain about 35 to 54 weight % of phosphorus, about 35 to 47 weight % of nitrogen, about 1 to 20 weight % of oxygen and about 0.1 to 8 weight % of chlorine.

Abstract: Self-extinguishing laminates are made by an improved process, wherein individual layers of a carrier material are impregnated with a thermosetting phenolic resin containing a flame-retardant agent and the impregnated layers are placed one above another and bonded together by compressing them at elevated temperature and under elevated pressure to give a hardened laminate. More specifically, finely pulverulent phosphorus pentanitride as a flame-retarding agent is dispersed in the plasticized or non-plasticized thermosetting phenolic resin, with or without a diluent; the phenolic resin, based on its solid matter content, and the phosphorus pentanitride being used in an approximate ratio by weight of 100:4 to 100:15; and the phenolic resin, based on its solid matter content, and the carrier being used in an approximate ratio by weight of 100:80 to 100:150.

Abstract: Phosphorus nitrides of the general formula PN.sub.x, in which x stands for a number of 0.9 up to 1.7 are made. To this end, phosphorus halides are reacted with ammonia in gas phase, the ammonia being used in excess based on the phosphorus halides, and the resulting reaction product is heated to temperatures of up to 950.degree. C until ammonia practically ceases to be evolved from the reaction product.

Abstract: Flame-retardant fibers of regenerated cellulose are produced by adding one or more flame-retardant phosphorus compounds to the viscose, extruding the viscose into a spinning bath and, if desired, stretching and after-treating the resulting filaments or staple fibers. The flame-retardant agent is a compound of the general formulaPN.sub.x O.sub.yin which x stands for a number between 0.9 and 1.7 and y stands for a number between 1.2 and 0, where the y-values converge towards zero as the x-values increase. The flame-retardant agent is more particularly used in a proportion approximately between 5 and 30 weight %, based on the weight of the cellulose.

Abstract: Phosphorous acid is produced from PCl.sub.3 and water in an apparatus, the essential parts of which include a reactor and an evaporator, which are connected together by means of a conduit running from the bottom of the reactor to the head of the evaporator. The evaporator communicates with the lower end of a separator of which the upstream end terminates in an off-gas outlet. More particularly, the downstream end of the evaporator is connected to a stripping column which is provided with an off-gas outlet opening into the off-gas outlet associated with the evaporator.