o 2 was added to the pulp the ph was 7 8 the bleaching conditions were 17 pulp consistency 80 c 2 5 hours the subsequent procedures were the same as those in example 1 the residual peroxide was 0 66 end ph was 6 9 and the brightness of the resulting pulp was 70 1 iso in the control process 0 1 dtpa 1 mg oh 2 slurry and 2 h 202 were added to the pre heated pulp at 20 pulp consistency and 80 c the ph was 7 9 the bleaching conditions and subsequent procedures were the same as those above the residual peroxide was 0 58 the end ph was 7 2 and the brightness of resulting pulps was 69 4 the above results show that the benefit of the p m process is still apparent even mg oh 2 instead of naoh was used as the alkali source during peroxide bleaching the initial ph in this series of examples 7 to 11 did not exceed 11 0 for conventional peroxide bleaching conditions a fairly extreme example went to 11 3 and it is contemplated that the initial ph would never exceed 11 5 furthermore the ph at the end of the bleaching process was not more than about 8 7 this would normally not exceed 9 0 and in an extreme case should not exceed 9 5 a stoneground wood pulp sgw with an initial brightness of 57 6 iso was used in the p m process 1 mg.