iii and iv show that using split flow the permanganate number can be reduced by 45 54 before the viscosity is reduced to the same extent noted in full flow through said chamber 6 a similar trend perhaps not as pronounced is noted with the paper grade pulp examples vi and vii show that full flow gave kappa number reductions of 34 2 and 40 0 with corresponding viscosity losses of 43 7 and 49 2 using split flow of the present invention the lower level of delignification was achieved with only 33 1 loss of viscosity example viii while at the higher level of kappa reduction examples ix and x show the consistent superiority of the split flow method of the invention table ii below shows several additional examples of desirable operating conditions embodying the present invention in these examples the unbleached pulp initially was at 10 consistency diluted to high pressure reactor 6 consistency with alkali a 4 8 g l and at a temperature of 140 u00b0 f outlet of the reactor was at a temperature of 203 u00b0 f in these examples example xiii is a comparison example showing total flow through the pre retention reactor 6 as in that process of u s pat no 3 832 276 table ii__________________________________________________________________________ fraction of naoh conc flow through in high tower 8 consistency in temp u00b0 f in pressure not passinghigh pressure high pressure pre retention throughexamplepre retention pre retention reactor 6 pre retentionno reactor 6 reactor 6 g 1 reactor 6 __________________________________________________________________________xi 5 245 2 4 1.