This is good comment about it from yahoo answers:
If they are photographs, NOT INK JET/LASER prints, you should put them in a tray of water at about room temperature and let them soak for at least an hour. Remember true photo paper was designed to be processed in liquid chemistry! Once they have absorbed enough moisture they should separate very easily but the image will be soft and fragile so handle gently!
You could add "Photo Flo" (available at a photo stores that still sell chemical processing supplies) or a very small amount of plain dish detergent to the water. Once they have soaked they should separate easily, if they don't, DO NOT pull them apart! Add some warm water and let them continue to soak until they have absorbed enough moisture to separate easily.
Dry the images by laying them FACE UP on a soft towel laid on a table or wire rack or suspend them from a string using PLASTIC clothes pins. The pictures may curl up while they are drying but the curl can be removed after they are completely dry by uncurling them and placing a heavy book or other weight on top pf them.
40+ Years as a photo processor and photographer.
You could try heating a pot of water on the stove. Then hold pictures over the steam and see if they separate. Worth a try.
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