Abstract: An apparatus for metering and mixing dry particulate additive with a dry particulate plastic material prior to heating the mixture and molding or injecting the same to form a finished article. The apparatus includes a vertically disposed feed throat tube through which the plastic material is adapted to be fed downwardly into the processing machine. A horizontally directed tubular member extends into the feed throat tube for delivering the additive, the tubular member including vertically aligned upper and lower openings and an open forward end positioned within the feed throat tube. By this arrangement, a portion of the plastic material enters the tubular member through the upper opening and is mixed with the additive therein, and the mixture falls through the lower opening and the open forward end of the tubular member.