419,790. Treatment of white water of paper pulp. NEW JERSEY ZINC CO., 160, Front Street, New York, U.S.A.- (Assignees of Cyr, H. M. ; Palmerton, Pennsylvania, and' Kress, 0.; Appleton, Wisconsin, both in U.S.A.) March 23, 1934, No. 9206. Convention date, April 17, 1933. [Class 96.] White water of paper-manufacture is sterilized and disinfected by a zinc pigment, thus allowing it to be recirculated without the formation of bacterial slimes. The zinc pigment may be added to the white water, or to paper pulp e.g. at the beater in such amount e.g. 1-10 per cent, that the white water contains sufficient. The pigment may comprise zinc sulphide, zinc oxide, lithopone, mixtures of zinc sulphide with calcium sulphate or an alkaline earth carbonate. In one form alum is added to pulp to establish a pH value of 4À5 or higher and just prior to discharging the pulp zinc pigment e.q. with alkali is added to raise the pH value to 5À0 or higher. The paper-making machinery is preferably flushed with water before use to remove soluble copper compounds. Specification 419,582 is referred to.