2 7 g of the phosphonic acid derivatives in its acid form c identical with bath a to which was added 0 4 g of hydrazine d identical with bath a to which was added 2 7 g of the phosphonic acid derivative previously neutralized with sodium hydroxide e identical with bath a to which was added 4 g sodium salt of u03b1 hydroxy methane sulfinic acid the samples were treated in the different baths for 1 hour while keeping the temperature at 95 u00b0 c the bath ratio being 1 to 10 after rinsing acidification and drying the following results were found practically total elimination of the puces of the fiber on the sample treated with batch b presence of puces was on the other hand still very clearly visible on all other samples as in the preceding examples determination of the level of whiteness showed a very considerable improvement of this characteristic by treatment in the presence of hydrazine phosphonate the reemission values were the following the conditions of example 3 were repeated using the following baths 3 7 g of double phosphonate of hydrazine and sodium used in example 3 so as to introduce in the bath 0 38 g per liter of hydrazine and 2 5 g per liter of phosphonic acid.