Abstract: Production of O,O-dialkylthionophosphoric acid chlorides of the general formula: ##STR1## in which R is an alkyl radical having from 1 to 6 carbon atoms, by reacting a dialkyldithiophosphoric with chlorine. A reactor is supplied with O,O-dialkyldithiophosphoric acid and chlorine is added thereto at a temperature lower than about 75.degree. C.; following completion of the chlorine addition, the reactor is supplied with a further portion of O,O-dialkyldithiophosphoric acid at a temperature between 0.degree. and 75.degree. C., and the resulting reaction mixture is distilled to isolate O,O-dialkylthionophosphoric acid chloride therefrom.

Abstract: Alkali metal phosphate solutions of low vanadium content are produced from wet-processed phosphoric acids contaminated with vanadium and iron. The acids containing vanadium and iron in the highest stage of oxidation are treated with a reductant to effect conversion of the vanadium and iron contaminants to a lower stage of oxidation, the resulting acids are neutralized by means of an alkaline liquor and/or alkali metal carbonate down to a pH of at least 3, and the resulting precipitate is separated. The reductant used is the sodium salt of hydroxymethane-sulfinic acid.

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.