AUTHORS' REPLIES

Mr C. B. Townend (Joint Author of Paper 8) observed that, DIOO. In spite of all these advances, however, there must always during the past 30 or 40 years, there had come about a great be some small oxygen demand remaining—even if only 2 % or 3 % change of outlook in the relations between personnel of river of the original amount—and other residual substances mentioned authorities and main drainage authorities, who in these enin the discussion which were just as impracticable to remove lightened days were working closely together—indeed as memcompletely in sewage treatment as had proved to be the case with bers of the same professional association—in the general water treatment processes. It might be that where such substance interests of river conservation. had originated in trade waste discharges, some appropriate pre