Photographic product and process for forming a white image viewable against a dark background

Claim 1

A PHOTOGRAPHIC PRODUCT COMPRISING A PLURALITY OF LAYERS INCLUDING AT LEAST A PHOTOSENSITIVE SILVER HALIDE LAYER, A BASE LAYER FOR RECEIVING A REVERSE IMAGE OF A LATENT IMAGE IN SAID PHOTOSENSITIVE LAYER, AND A CONTAINER HOLDING AT LEAST AN ALKALINE LIQUID SOLVENT COMPOSITION FOR A PHOTOGRAPHIC DEVELOPER, SAID PHOTOSENSITIVE LAYER, SAID BASE LAYER AND SAID CONTAINER BEING SO ARRANGED AS TO PERMIT AT LEAST A PORTION OF SAID BASE LAYER AND SAID PHOTOSENSITIVE LAYER TO BE SUPERPOSED WITH SAID CONTAINER POSITIONED FOR RELEASE OF ITS LIQUID CONTENT BETWEEN TWO LAYERS OF SAID PRODUCT FOR PERMEATION OF SAID PHOTOSENSITIVE AND SAID BASE LAYERS UPON RUPTURE OF THE CONTAINER, SAID PRODUCT HAVING POSITIONED THEREIN A SILVER HALIDE DEVELOPER, SAID DEVELOPER BEING SOLUBLE IN SAID COMPOSITION AND BEING RENDERED EFFECTIVE UPON RELEASE OF SAID COMPOSITION TO DEVELOP A LATENT NEGATIVE IMAGE IN SAID PHOTOSENSITIVE LAYER OF A SUBJECT TO WHICH SAID PHOTOSENSITIVE LAYER HAS BEEN EXPOSED AND, AS A RESULT OF SAID DEVELOPMENT, CAUSING AN IMAGEWISE VARIATION IN THE ALKALINITY OF SAID LIQUID COMPOSITION WHEREBY THE ALKALINITY OF THE COMPOSITION ADJACENT AREAS OF DEVELOPED SILVER IS LOWERED, SAID PRODUCT, IN ADDITION, INCLUDING IN SAID BASE LAYER FOR SAID REVERSE IMAGE A SUBSTANTIALLY UNIFORM DISTRIBUTION OF A MATERIAL COMPRISING AT LEAST ONE METALLIC SALT WHICH IS SOLUBLE IN SAID LIQUID COMPOSITION AND WHICH HAS A METALLIC ION REACTABLE WITH THE HYDROXYL ION OF SAID LIQUID COMPOSITION TO FORM A WHITISH PRECIPITATE WHEN THE ALKALINITY OF SAID LIQUID COMPOSITION HAS BEEN LOWERED AS A RESULT OF DEVELOPMENT WHEREBY TO PROVIDE A REVERSE IMAGE OF SAID DEVELOPED LATENT IMAGE IN TERMS OF THE HIGHLIGHTS OF SAID SUBJECT, SAID DEVELOPER BEING IN A QUANTITY SUFFICIENT TO DISSOLVE DEVELOP SAID LATENT IMAGE AND SAID LIQUID COMPOSITION BEING IN A QUANTITY SUFFICIENT TO DISSOLVE ALL OF SAID DEVELOPER AND TO REACT, IN PLACES WHERE SILVER DEVELOPMENT HAS OCCURRED, WITH SAID METALLIC SALT TO PROVIDE SAID REVERSE IMAGE, AND SAID PRODUCT INCLUDING AN OPAQUE, BLACK, WATER-PERMEABLE LAYER CARRIED BY SAID PHOTOSENSITIVE LAYER ON THE SIDE THEREOF ADAPTED TO BE POSITIONED IN FACING RELATION TO SAID BASE LAYER WHEN THE PHOTOSENSITIVE LAYER AND THE BASE LAYER ARE SUPERPOSED, AND WHEREIN SAID BASE LAYER IS TRANSPARENT AND SAID BLACK LAYER PROVIDES NONHALATION MEANS AND, IN ADDITION THERETO, A BLACK BACKGROUND AGAINST WHICH SAID REVERSE IMAGE FORMED OF WHITE PRECIPITATE IS READILY VIEWABLE.