Mercuric iodide intensification of silver gelatin negatives produces unstable negatives which over time take on a more or less uniform lemon-yellow coloration accompanied by a loss of contrast. After having found evidence of mercury and silver iodide salts in deteriorated original negatives, the author reproduced the deterioration on modern flexible support negatives and glass plate negatives using accelerated aging techniques. A method of restoration through development produced the return of image contrast, as well as stabilizing the image. The risk of delamination of the binder layer from the glass supports was minimized by controlling the pH of the re-development bath. Measurements were taken of the swelling induced in the gelatin layer by the various procedures.