desirable cellulosic material previously converted in form as into packaging structural or waste materials may be suitable comminution may be accomplished by conventional means and methods as noted such as chipping chopping or shredding and grinding ball milling cold etc preferably means and methods employed should be of low temperature type to avoid any excessive localized heating of the material as might degrade it chemically as by charring or block it from reagents as by imparting a rather impermeable glaze to normally permeable cell walls etc as already mentioned the environmental gas of this invention is rich in carbon dioxide comprising carbon dioxide in major part and indeed preferably consisting essentially of carbon dioxide the environmental gas should be substantially free of air and its major constituents and be similarly free of water as well the purging or sweeping and decompression steps are intended to remove air water acids alkalis oils volatiles finer particulates such as dust and smoke and other undesirable foreign matter from the cellulosic material preliminary to further chemical conversion the successive pressurization and depressurization of the material also the ultrasonic vibration thereof are effective in improving access of chemical agents to the cellulose interior by opening it up to some extent the enhanced access to the cellulose interior is ascertainable on a macro scale as by determining its porosity in conventional manner the porosity also may be evident microscopically as either a rupturing of cell walls or a fracturing of the matrix within which bundles.