Abstract: Method for increasing the sensitivity of a photographic silver halide-gelatin emulsion comprising at the beginning of the chemical ripening adding to the emulsion of a dithioester of the formula: ##STR1## in which R is alkyl, .alpha.-hydroxyalkyl, .alpha.-hydroxyaralkyl, condensed aryl, or o- or p-substituted phenyl or .alpha.-naphthyl, the o- or p- located substituent being a F, OH, dialkylamino, sulfo, phenyl, phenylazo or anilidocarbonyl group and R.sub.1 is alkyl or aralkyl.

Abstract: A process for the preparation of cellulose fibers from cellulose containing chips wherein the cellulose containing chips are subjected to a chemical process for the purpose of separating the cellulose from lignin and other extraneous chemicals which prior to digestion of the chips subjecting the chips to a two-step pre-treatment by:1. contacting said chips with an aqueous solution of an alkali metal, alkaline earth metal or ammonium sulfite or bi-sulfite metal; and,2. thereafter radiating the so pre-treated chips by contacting them with charged particles.