Collapsible fluid container

Claim 1

A COLLAPSIBLE, FLUID-CARRYING CONTAINER OF THE TYPE USED IN PHOTOGRAPHIC PROCESSES WHEREIN SAID CONTAINER IS POSITIONED BETWEEN A PAIR OF SHEET MATERIALS WHICH ARE ADVANCED IN SUPERPOSED RELATION BETWEEN PRESSURE-APPLYING MEMBERS TO EFFECT RELEASE OF SAID FLUID AND SPREADING THEREOF IN A UNIFORMLY THIN LAYER BETWEEN SAID SHEETS TO EFFECT PHOTOGRAPHIC PROCESSING OF AT LEAST ONE OF SAID SHEETS, SAID CONTAINER COMPRISING: (A) A PAIR OF SUBSTANTIALLY RECTANGULAR, OPPOSED WALL MEMBERS; (B) MEANS SECURING TOGETHER MARGINAL PORTIONS OF ALL FOUR SIDES OF SAID WALL MEMBERS TO FORM A SINGLE, ENCLOSED CAVITY; (C) A VISCOUS FLUID CONTAINED WITHIN SAID CAVITY; (D) AT LEAST ONE OF SAID WALL MEMBERS BEING FLEXIBLE AND DEFORMABLE WHEREBY A HYDRAULIC PRESSURE IS EXERTED BY SAID FLUID UPON APPLICATION OF A COMPRESSIVE FORCE UPON ADVANCEMENT OF SAID CONTAINER BETWEEN SAID PRESSURE-APPLYING MEMBERS TO SAID CONTAINER; AND (E) THREE OF SAID FOUR SIDES AND A CENTRALLY DISPOSED PORTION OF THE FOURTH SIDE BEING SECURED TOGETHER IN SAID MARGINAL PORTIONS BY A STRONGER BOND THAN THAT SECURING SAID FOURTH SIDE IN OTHER THAN SAID CENTRALLY DISPOSED PORTION, WHEREBY SAID FLUID IS RELEASED UPON APPLICATION OF SAID FORCE TO SAID CONTAINER FROM SAID FOURTH SIDE ON EACH SIDE OF SAID CENTRALLY DISPOSED PORTION.